WO2018036417A1 - Flue gas clean up method using a multiple system approach - Google Patents

Flue gas clean up method using a multiple system approach Download PDF

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WO2018036417A1
WO2018036417A1 PCT/CN2017/097804 CN2017097804W WO2018036417A1 WO 2018036417 A1 WO2018036417 A1 WO 2018036417A1 CN 2017097804 W CN2017097804 W CN 2017097804W WO 2018036417 A1 WO2018036417 A1 WO 2018036417A1
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sodium
scrubber
potassium
scrubbing
wet
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PCT/CN2017/097804
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French (fr)
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Murray Mortson
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Airborne China Limited
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L9/00—Treating solid fuels to improve their combustion
    • C10L9/10—Treating solid fuels to improve their combustion by using additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/75—Multi-step processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L10/00—Use of additives to fuels or fires for particular purposes
    • C10L10/02—Use of additives to fuels or fires for particular purposes for reducing smoke development
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2200/00—Components of fuel compositions
    • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
    • C10L2200/0204—Metals or alloys
    • C10L2200/0209—Group I metals: Li, Na, K, Rb, Cs, Fr, Cu, Ag, Au
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2200/00—Components of fuel compositions
    • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
    • C10L2200/0204—Metals or alloys
    • C10L2200/0213—Group II metals: Be, Mg, Ca, Sr, Ba, Ra, Zn, Cd, Hg
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2200/00—Components of fuel compositions
    • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
    • C10L2200/0204—Metals or alloys
    • C10L2200/0236—Group VII metals: Mn, To, Re
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2200/00—Components of fuel compositions
    • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
    • C10L2200/0204—Metals or alloys
    • C10L2200/024—Group VIII metals: Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2200/00—Components of fuel compositions
    • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
    • C10L2200/0272—Silicon containing compounds
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L2200/00—Components of fuel compositions
    • C10L2200/02—Inorganic or organic compounds containing atoms other than C, H or O, e.g. organic compounds containing heteroatoms or metal organic complexes
    • C10L2200/029—Salts, such as carbonates, oxides, hydroxides, percompounds, e.g. peroxides, perborates, nitrates, nitrites, sulfates, and silicates

Definitions

  • the present invention relates to a flue gas purification method, and more particularly, the present invention relates to a complete flue gas control system that modifies the combustion characteristics and combines a flue gas purification method incorporating with and without selective non-catalytic reduction or selective catalytic reduction nitrogen oxides reduction techniques, or dry sorbent injection or/and wet scrubbing unit operations with and without chemical oxidants to substantially eliminate sulfur dioxide, sulfur trioxide, particulate matter (PM) , mercury, arsenic, selenium and nitrogen oxides compounds (NO, NO 2 , N 2 O 5 etc.) as well as other air toxic compounds such as VOC’s and dioxins from the flue gas created from the combustion of hydrocarbons such as coal or any other fuel.
  • a flue gas purification method incorporating with and without selective non-catalytic reduction or selective catalytic reduction nitrogen oxides reduction techniques, or dry sorbent injection or/and wet scrubbing unit operations with and without chemical oxidants to substantially eliminate sulfur dioxide, sulfur trioxide
  • the prior art establishes a number of wet chemical absorption methods which primarily incorporate wet scrubbers where a hot contaminated gas is scrubbed or detoxified in a gas liquid contact apparatus with a neutralizing solution.
  • the neutralizing solution can typically be any suitable aqueous alkaline liquid or slurry to remove sulfur oxides and other contaminants present in the flue gas stream.
  • the gas liquid contact apparatus are generally employed by power generating stations and use the wet chemical absorption arrangement incorporating sodium, calcium, magnesium, etc. to desulfurize flue gas.
  • Johnson et al. in United States Patent No. 6,303,083, issued October 16, 2001, disclose a SO X removal process for flue gas treatment.
  • a specific particle larger than 1 to 2 microns size range for the sorbent is reacted with the flue gas to reduce SO 3 content.
  • the treated flue gas is then reacted in a wet scrubber to reduce SO 2 content.
  • the wet scrubbing systems that employ lime, limestone, soda ash or other alkaline compositions demonstrate efficacy for removal of sulfur dioxide, but are significantly less efficient at the removal of sulfur trioxide or sulfuric acid aerosol and have no effect on NO removal.
  • NO is typically 95%of the nitrogen oxides formed during combustion.
  • the methodology set forth herein alleviates all of the limitations in the prior art techniques by first reducing the formation of pollutants by systematically removing them by catalytic combustion or adding chemicals additive for combustion enhancement into the boiler, and/or combination SNCR or SCR with optional various scrubbing systems detailed below.
  • the object of the present invention is to provide an improved method for flue gas pollutant reduction.
  • a method of removing air pollutant from a flue gas stream characterized in that the method comprises:
  • catalytic combustion operation adding a chemical additive as a combustion enhancer into a combustion equipment, in which a fuel such as a coal or bio-fuels combust more completely while adding the combustion additive, wherein the additive is a mixture containing the elements of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn 3 O 4 ) .
  • a chemical additive as a combustion enhancer into a combustion equipment, in which a fuel such as a coal or bio-fuels combust more completely while adding the combustion additive, wherein the additive is a mixture containing the elements of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn 3 O 4 ) .
  • the fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfite, sodium sulfate, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfite, potassium sulfate, potassium carbonate, potassium bicarbonate and potassium hydroxide.
  • the denitrification process is the process through selective catalytic reduction operation, wherein vanadium, platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature; preferably, vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430°Cduring the selective catalytic reduction operation.
  • a flue gas stream possibly containing mercury, arsenic, selenium, particulate matter, sulfur oxides and/or nitrogen oxides compounds is contacted with a sorbent selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate, potassium hydroxide, calcium carbonate, calcium bicarbonate, calcium hydroxide, magnesium carbonate, magnesium bicarbonate and magnesium hydroxide, during (a) the step of a dry injection scrubbing operation; wherein the sorbent is preferably one or more selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate and sodium hydroxide.
  • a basic solution comprises one or more compound selected from sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate and potassium hydroxide; preferably a basic solution comprises one or more compound selected from sodium carbonate, sodium sulfate, and sodium sulfite, more preferably a basic solution with pH 6.5-11, preferably 8.5-11, which predominately comprises a mixture of sodium carbonate, sodium sulfate, sodium sulfite and sodium nitrate, is added in the scrubber during (b) the step of a wet scrubbing operation.
  • oxidant is one or more selected from the group consisting of hydrogen peroxide, potassium permanganate, sodium persulfate, hydroxyl; radicals, ozone and NaClOx, where x is 1 through 4.
  • air pollutant include any one material selected from particulate matter, VOC, dioxins, heavy metal such as mercury, arsenic, selenium etc, SOx and NOx compounds and any combination thereof.
  • a method of removing air pollutant from a flue gas stream characterized in that the method comprises:
  • a process of adding a fuel conditioning agent is added into a combustion equipment during combustion operation, in which a fuel such as a coal or bio-fuels are charged before or after or while adding the fuel additive.
  • the fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfite, sodium sulfate, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfite, potassium sulfate, potassium carbonate, potassium bicarbonate and potassium hydroxide.
  • a basic solution comprises one or more compound selected from sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate and potassium hydroxide; preferably a basic solution comprises one or more compound selected from sodium carbonate, sodium sulfate, and sodium sulfite; more preferably a basic solution with pH 6.5-11, preferably 8.5-11 which predominately comprises a mixture of sodium carbonate, sodium sulfate, and sodium nitrate, is added in the scrubber during (b) the step of a wet scrubbing operation.
  • oxidant is selected from the group consisting of hydrogen peroxide, potassium permanganate, sodium persulfate, hydroxyl radicals, sodium persulfate, ozone, NaClOx, where x is 1 through 4.
  • a method of removing air pollutant from a flue gas stream characterized in that the method comprises:
  • the denitrification process is the process through selective catalytic reduction operation, wherein vanadium, platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature; preferably, vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430°Cduring the selective catalytic reduction operation.
  • a basic solution comprises one or more compound selected from sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate and potassium hydroxide; preferably a basic solution comprises one or more compound selected from sodium carbonate, sodium sulfate, and sodium sulfite; more preferably a basic solution with pH 6.5-11, preferably 8.5-11 which predominately comprises a mixture of sodium carbonate, sodium sulfate, and sodium nitrate, is added in the scrubber during (b) the step of a wet scrubbing operation.
  • oxidant is selected from the group consisting of hydrogen peroxide, potassium permanganate, sodium persulfate, hydroxyl radicals, ozone, NaClOx, where x is 1 through 4.
  • the chemical additive added into the fuel combustion equipment in 0.01-0.05 weight %of a weight ratio of the fuel; preferably, the chemical additive is a mixture of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn 3 O 4 ) ; more preferably, the chemical additive includes Mn 3 O 4 17-51wt% of Manganese, Fe 5-16wt. %, CaO 3-35 wt. %and SiO 2 2-11%.
  • the chemical additive is a mixture of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn 3 O 4 ) ; more preferably, the chemical additive includes Mn 3 O 4 17-51wt% of Manganese, Fe 5-16wt. %, CaO 3-35 wt. %and SiO 2 2-11%.
  • the chemical additive comprises Mn 3 O 4 20-48%. by weight of Mn, Fe 8-14 wt. %, CaO 10-35 wt. %and SiO 2 5-10%; In an more preferably embodiments, for the chemical additive, it comprises Mn 3 O 4 40-51wt%Mn, Fe 11-16 wt. %, CaO 17-33 wt. %and SiO 2 5-11%.
  • a method of conditioning the PM collection efficiency of an electrostatic precipitator wherein a fuel conditioning agent is added into the fuel before or during combustion of a fuel.
  • a method of reducing the formation of particulate matter, sulfur oxides, nitrogen oxides and mercury, arsenic, selenium and then scrubbing the particulate matter, mercury, arsenic, selenium, sulfur oxides and nitrogen oxides compounds from a flue gas stream characterized in that the method comprises: primarily catalytic combustion to speed up desired oxidation reactions of coal or bio-fuels, so as to reduce the formation of undesired products of sulfur dioxide, nitrogen oxides, mercury, arsenic, selenium and particulate matter; sodium sulfate injection into the boiler, to reduce particulate matter escaping from PM absorption device such as the electrostatic precipitator etc., a selective non-catalytic reduction system and/or a selective catalytic reduction system for further nitrogen oxides reduction, a dry injection scrubbing operation, and/or a wet scrubbing operation which may or may not include specific scrubber internals for enhanced particulate
  • Said dry injection operation includes injection of sodium or potassium compounds into the boiler combustion system, contacting a flue gas stream containing sulfur oxides and nitrogen oxides, mercury, arsenic, selenium compounds and particulate matter with a sorbent selected from the group consisting of sodium bicarbonate, sodium carbonate, sodium hydroxide, potassium bicarbonate, potassium carbonate, potassium hydroxide and combinations thereof, for removing substantially all of the sulfur oxides, mercury, arsenic, selenium and a large amount of nitrogen oxides compounds present in said stream; said wet scrubbing operation includes: scrubbing said stream from said dry injection scrubbing operation; and said oxidation operation includes: adding an oxidant to said flue gas stream subsequent to said wet scrubbing operation, the wet scrubbing operation and the oxidation operation removing any residual mercury, arsenic, selenium, particulate matter, sulfur oxides and nitrogen oxides compounds remaining in said flue gas stream.
  • a sorbent selected from the group consisting of sodium bi
  • Suitable oxidants include hydrogen peroxide, ozone, potassium permanganate, sodium persulfate, hydroxyl radicals, NaClOx, where x is 1 through 4, or a combination thereof all used in specific pH regimes by the addition of acids or NaOH.
  • the method of this invention further includes the step of recirculating unreacted sorbent to said wet scrubbing operation.
  • typically said stream from said dry injection process produces sodium sulfate, sodium sulfite, sodium fluoride, sodium chloride, sodium nitrate, sodium nitrite, sodium carbonate, and all the potassium compounds of potassium sulfate, potassium sulfite, potassium fluoride, potassium chloride, potassium nitrate, potassium nitrate, and potassium carbonate.
  • This present invention reduced the formation of the pollutants firstly by the addition of a catalytic combustion chemical process to speed up desired oxidation reactions of coal or bio-fuels so as to reduce the formation of undesired products, especially particulate matter, nitrogen oxides, carbon dioxide, mercury, arsenic, selenium and sulfur oxides far below what can be achieved without chemical additives.
  • the most important attributes are: fuel oxidation to release more heat energy and reduce coal usage which naturally results in the reduction of nitrogen oxides, mercury, arsenic, selenium, particulate matter and sulfur oxides into the flue gas thus reducing emissions of these dangerous pollutants into the air, the destruction of other pollutant gases, re- burning of CO in the flue gas.
  • Most hydrocarbons are consumed in the optimized combustion process thus reducing particulate emissions considerably.
  • Lower temperature combustion also burns out the normal black acid smut emissions through the smoke stack which reduces the soot.
  • the chemical additive usually causes tars and hydrocarbons to burn out more completely releasing oxygen at the point of combustion, which changes and manipulates the base/acid ratio, so doing increases the ash fusion temperature.
  • the chemical additive also improves the combustion which means drier and softer more friable build-up in the boiler which results in longer periods between shut downs and an easier cleaning with high pressure water.
  • a chemical additive is also named catalyst and said catalytic combustion means the combustion of a fuel in the presence of a fuel additive.
  • the weight ratio of a chemical additive to a fuel is not a special requirement.
  • the addition amount of a chemical additive is enough to arrive at the complete combustion of the fuel.
  • the weight ratio of a chemical additive to the coal is in the range of 100 grams to 500 grams per tonne of coal. This all takes place without the chemical additive being consumed or altered in its chemical form after the reaction is complete.
  • the combustion chemical additive is a highly refined mineral compound including manganese, iron, magnesium, calcium, etc, with the main ingredient manganese (Mn 3 O 4 ) .
  • the chemical additive the chemical additive includes Mn 3 O 4 17-51wt. %of Mn, Fe 5-16 wt. %, CaO 3-35wt. %and SiO 2 2-11%, the rest is moisture and various minor compounds that comes with the main ore.
  • the chemical additive can be obtained by mixing all the ingredients of the ore MnO 2 , MnO, Fe, SiO 2 and CaO, and heating them through a common firing method (at the temperature of 800-1500°C) so as to make Fe, Si, Ca, Al loaded in Mn 3 O 4. In fact, the sum of the weight percentage of all the components is 100weight%.
  • the chemical additive usually contains Mn 3 O 4 , Fe, SiO 2 , CaO, Al 2 O 3 , S and H 2 O.
  • the element of Mn, Fe, Si and Ca are the most active ingredients, which functions as enhancing the combustion of the fuel making the fuel more fully combust.
  • the chemical additive can be obtained through all kinds of common methods as long as the obtained chemical compound or composition includes the above-identified ingredients Mn, Fe, SiO 2 and CaO, other ingredients such as any one substance or element selected from Al, Mg, K, Ti, Ba, P and S and H 2 O, may be mixed into the chemical additive as impurities, wherein Mn 3 O 4 can be obtained by heating a mixture of MnO 2 and MnO through firing method at the temperature of above 1000°C.
  • the content of Mn 3 O 4 is calculated based on Mn, that is, the content of Mn 3 O 4 does not consider the content of the element of oxgen in the compound of Mn 3 O 4 ;
  • the content of SiO 2 is calculated based on Si, that is, the content of SiO 2 does not consider the content of the element of oxgen in the compound of SiO 2 ;
  • the content of CaO is calculated based on Ca, that is, the content of CaO does not consider the content of the element of oxygen in the compound of CaO.
  • the chemical additive is non-toxic, non-poisonous, non-combustible and non-chemical based. In the presence of carbon and oxygen the chemical additive reacts to increase/improve the combustion rate. At the same time the chemical additive lowers the temperature at which the reactions will occur. This in itself avoids low temp evaporation and stops the escape of hydrocarbons as is usual, and rather burning them out to avoid sticky wet attachment to the inside of the boiler.
  • the chemical additive preferably contains the following ingredients by weight: Mn 51%, Fe 16%, Si 11%, Ca 17%, Al 2 O 3 1%, S 0.5%, H 2 O 3.5%.
  • the chemical additive (Mn 3 O 4 /Iron/Silicon/Calcium, wherein Mn 3 O 4 is a carrier, Mn, Fe, Si and Ca are loaded in the carrier) including Mn 44%, Fe 11%, Si 7%and Calcium 33%by weight.
  • Manganese (II, III) oxide is the chemical compound that is the carrier chemical in this chemical additive with formula Mn 3 O 4 and is present in two+2and+3and the formula is sometimes written as MnO ⁇ Mn 2 O 3 .
  • Mn 3 O 4 is found in nature as the mineral Mn 3 O 4 formed when any manganese oxide is heated in air above 1000°C.
  • Mn 3 O 4 has been found to act as a catalyst for a range of reactions e.g. the oxidation of methane and carbon monoxide; the decomposition of NO.
  • the second pollutant removal step after the combustion modifications using the chemical additive is the addition of a fuel conditioner into the boiler or other combustion equipment to improve the electrostatic precipitator performance.
  • Fuel conditioning produced by sodium sulfite, sodium sulfate, sodium carbonate, sodium bicarbonate or sodium hydroxide; or potassium sulfite, potassium sulfate, potassium carbonate, potassium bicarbonate or potassium hydroxide addition to the coal supply provides an effective means of improving the performance of a hot-side electrostatic precipitator which has undergone sodium or potassium depletion, because of the high resistivity pattern of performance deterioration.
  • the electrostatic precipitator performance improvement can be explained as an equilibrium process in the depleted zone in which sodium (potassium) is transported to the depleted region by a thermally induced chemical diffusion process.
  • the reduction of ash resistivity appears to depend upon the equilibrium which is attained between the competing chemical and electrical transport processes.
  • the equilibrium point depends upon ash composition and certain design and operating parameters of the electrostatic precipitator. Emissions standards are becoming more stringer, as a result new retrofit/techniques are being applied in the existing power plants.
  • Electrostatic Precipitators are used typically to control fly ash emitting from the boilers in power plants.
  • the coal burned in power plants to generate the power are often characterized by low calorific value (3500-4500) Kcal/Kg., and high ash content (35-45) %.
  • this coal generates about 6 to 7 times more ash for collection for similar electricity generation and the low sulfur content results in the resistivity of fly ash being 100-1000 times higher than that generated elsewhere.
  • ESPs despite being much larger, have lower collection efficiencies.
  • One method which we have met with success, is the coal ash conditioning with sodium or potassium salt before feeding to boiler.
  • Flue gas conditioning with sodium or potassium refers to the addition of sodium or potassium based chemicals to the flue gas for modification of fly ash properties and/or electrical conditions in the ESP to improve the collection efficiency of ESPs.
  • flue gas conditioning with sodium or potassium chemicals is often the most cost effective way to upgrade performance.
  • Fuel conditioning agents influence the ESP collection efficiency through one or more of the following mechanisms: (1) adsorbing on the surface of fly ash to reduce surface resistivity; (2) adsorbing on the fly ash to change the adhesion and cohesion properties of the ash; (3) increasing ultrafine particle concentrations for space charge enhancement; (4) increasing the electrical breakdown strength of the flue gas, (5) increasing the mean particle size; and (6) changing the acid dew point in the flue gas.
  • Ash resistivity is indirectly related to the alkali content in the ash, and reduction of ash resistivity by increasing the alkali concentration was tried. Sodium chloride has been tried in the laboratory and found to be effective. However, it is not recommended because it can lead to corrosion of metal equipment. A sodium or potassium based conditioning agent will affect some or all of these factors.
  • the ash resistivity is important because it can affect both (1) and (2) above.
  • the mechanism for fuel conditioning depends on how the sodium or potassium is applied. If a sodium or potassium compound is injected into the boiler along with coal, it will decompose and the sodium (potassium) is bound in the ash. The sodium (potassium) will increase the conductivity and lower the ash resistivity in the same way as natural sodium and if a sulfate compound is used it will effectively increase the sulfur content of the coal. Care has to be taken to ensure the sodium or potassium sulfate is effectively and uniformly bound to the coal and that can be achieved in a commercial plant by slightly wetting the coal before spraying dry sodium or potassium sulfate onto the coal.
  • the sodium or potassium alkali compound is co-precipitated with the ash, the compound trapped in the space between the particles on the dust layer offers an additional conductive path for charge dissipation.
  • Fuel conditioning unlike with other conditioning agents, is not limited to cold-side ESPs. It can be added to the boiler along with coal. It can be applied either in solution or dry powder form. The most important parameter which affects its effectiveness is the mixing of the alkali salt and the fly ash. Generally, the adding amount of a fuel conditioning agent into a fuel is in the range of 1-10kg per tonne fuel when an agent is mixed with a fuel.
  • Said fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfate, sodium carbonate, sodium bicarbonate and sodium hydroxide, potassium sulfate, potassium carbonate, potassium bicarbonate, or potassium hydroxide.
  • the adding amount of sodium sulfate into a fuel is preferably in the range of 1-3kg per tonne coal; when said fuel conditioning agent is sodium bicarbonate, the adding amount of sodium bicarbonate into a coal is preferably in the range of 2-6kg per tonne coal; when said fuel conditioning agent is sodium carbonate, the adding amount of sodium carbonate into a coal is preferably in the range of 1-3kg per tonne coal; when said fuel conditioning agent is sodium hydroxide, the adding amount of sodium hydroxide into a coal is preferably in the range of 0.52-1.65kg per tonne coal.
  • Sodium compounds are more often used due to the preferred pricing over the similar potassium substances.
  • the sodium must be either incorporated into all the ash particles or co-precipitated with the ash on the ESP plates so it yields well-mixed deposits.
  • the function of fuel conditioning agent on conditioning the electrostatic precipitator operating characteristics is determined by the following test.
  • the sodium sulfate by-product was delivered from the silo to the coal feeder belt by a screw feeder at a rate ranging from 0.08 to1 weight%sodium sulfate to a coal, preferably, from 0.09 to 0.6 weight%sodium sulfate to a coal; more preferably, from 0.1 to 0.3 weight%sodium sulfate to a coal.
  • the third pollution removal step may or may not be the use of a selective non-catalytic reduction or selective catalytic reduction system.
  • the selective non-catalytic reduction or selective catalytic reduction systems could work in conjunction with the coal chemical additive used as a combustion enhancer and in certain cases using traditional low nitrogen oxides combustion burners selective non-catalytic reduction or selective catalytic reduction might not be needed for compliance with current nitrogen oxides regulations. Additionally, there will be situations wherein the client has in place selective non-catalytic reduction or selective catalytic reduction systems and they will be in use for the integrated pollution control system.
  • the selection of a selective catalytic reduction or a selective non-catalytic reduction in conjunction with the coal fuel additive, and dry sorbent injection system plus chemical oxidants will be based on nitrogen oxides pollution requirements and economics.
  • SCR is a process that involves post-combustion removal of NOx from flue gas with a catalytic reactor.
  • ammonia injected into the exhaust gas reacts with nitrogen oxides and oxygen to form nitrogen and water.
  • the reactions take place on the surface of a catalyst bed.
  • the function of the catalyst is to effectively lower the activation energy of the NOx decomposition reaction.
  • Technical factors related to this technology include the catalyst reactor design, optimum operating temperature, sulfur content of the fuel, catalyst de-activation due to aging or poisoning, ammonia slip emissions, and design of the ammonia injection system.
  • the SCR system is comprised of a number of subsystems. These include the SCR reactor and flues, ammonia injection system and ammonia storage and delivery system.
  • the SCR reactor with necessary inlet and outlet duct work is located downstream of the economizer and upstream of the air heater and the particulate control system. From the economizer outlet, the flue gas will first pass through a low-pressure ammonia/air injection grid designed to provide optimal mixing of ammonia with flue gas. The ammonia treated flue gas will then flow through the catalyst bed and exit to the air heater.
  • the SCR system for a pulverized coal boiler typically utilizes a fixed bed catalyst in a vertical down flow multi-stage reactor.
  • the reactor will include a seal system to prevent gas from bypassing the catalyst bed.
  • the reactor will contain multiple stages of catalyst beds with room for loading future stages. For each stage, a soot blowing system is provided.
  • Reduction catalysts are divided into two groups: base metal (lower temperature, primarily vanadium, platinum or titanium) and zeolite (higher temperature) . Both groups exhibit advantages and disadvantages in terms of operating temperature, reducing agent/NOx ratio, and optimum oxygen concentration.
  • a disadvantage common to base metal catalysts is the narrow range of temperatures in which the reactions will proceed.
  • Platinum group catalysts have the advantage of requiring lower ignition temperature, but have been shown to also have a lower maximum operating temperature. Operating above the maximum temperature results in oxidation of ammonia to either nitrogen oxides (thereby actually increasing NOx emissions) or ammonium nitrate.
  • Optimum operating temperature for a vanadium-titanium catalyst system has been shown to be in the range of 280 to 430 °C, which is significantly higher than for platinum catalyst systems.
  • the vanadium-titanium catalyst systems begin to break down when continuously operating at temperatures above this range. Consequently, operating above the maximum temperature for the catalyst system again results in the oxidation of ammonia to either nitrogen oxides (increasing NOx emissions) or ammonium nitrate.
  • Sulfur content of the fuel can be a concern for systems that employ SCR.
  • Catalyst systems promote partial oxidation of sulfur dioxide to sulfur trioxide (SO 3 ) , which combines with water vapor to form sulfuric acid.
  • SO 3 and sulfuric acid react with excess ammonia to form ammonium salts.
  • These ammonium salts may condense as the flue gases are cooled and can lead to increased uncontrolled emissions of PM10 entering the particulate collector. Fouling may eventually lead to decreased NOx reduction performance; increased system pressure drop over time and decreased heat transfer efficiencies.
  • the present invention will eliminate this concern since the dry sorbent injection system will remove the SO 3 created from the catalyst bed reaction.
  • Catalyst deactivation occurs through two primary mechanisms: physical deactivation and chemical poisoning.
  • Physical deactivation is generally the result either of prolonged exposure to excessive temperatures or masking of the catalyst due to entrainment of particulate from ambient air or internal contaminants.
  • Chemical poisoning is caused by the irreversible reaction of the catalyst with a contaminant in the gas stream and is a permanent condition.
  • Catalyst suppliers typically only guarantee a limited lifetime to very low emission level, high performance catalyst systems.
  • SCR SCR
  • Safety issues and Risk Management Planning may be required relative to the transportation, handling, and storage of ammonia (aqueous or anhydrous) .
  • the present invention alleviates all of the downstream issues caused by SCR operations.
  • the SNCR process is based on a gas-phase homogeneous reaction, within a specified temperature range, between NOx in the flue gas and either injected NH 3 or urea to produce gaseous nitrogen and water vapor.
  • SNCR systems do not employ a catalyst bed; the NOx reduction reactions are driven by the thermal decomposition of ammonia and the subsequent reduction of NOx. Consequently, the SNCR process operates at higher temperatures than the SCR process.
  • Critical to the successful reduction of NOx with SNCR is the temperature of the flue gas at the point where the reagent is injected.
  • the necessary temperature range is 900-1,050°C; for the urea injection process the nominal temperature range is 850-1,150°C.
  • Also critical to effective application of these processes are gas mixing, residence time at temperature, and ammonia slip.
  • Pulverized coal-fired units have a limited furnace temperature window and poor lateral mixing, conditions which render SNCR less effective in these units.
  • SNCR has been applied to pulverized coal boilers more often to achieve 30-50% reductions since the technology can be retrofit more easily than other add-on controls. Due to mixing limitations and a brief temperature window in which to react, SNCR is fundamentally less effective at controlling NOx from boilers as compared with other combustion processes.
  • the present invention alleviates all of the concerns with SNCR operations.
  • the fourth pollution removal step is a scrubbing operation including one or more steps of a dry injection operation, a wet scrubbing operation in a scrubber and/or an oxidation scrubbing operation.
  • the scrubbing operation is unification of the dry injection pollution removal operation and a wet scrubbing operation with or without chemical oxidants. This works effectively and advantageously eliminates the concern for NOx brown plume, SO 3 emissions with the associated blue plume, and ammonia slip.
  • reaction of the sodium sorbents resulted in the synthesis of nitrogen oxides compounds as plume if the dry injection of sodium bicarbonate was collected in a bag house or electrostatic precipitator.
  • the nitrogen oxides compounds are soluble species and are easily managed by treatment with the wet scrubbing operation.
  • said dry injection scrubbing operation including:
  • a flue gas stream containing mercury, arsenic, selenium, particulate matter, sulfur oxides and nitrogen oxides compounds with a sorbent selected from the group consisting of sodium bicarbonate, sodium carbonate, sodium hydroxide, or the potassium based compounds and combinations thereof, for removing substantially all of the sulfur oxides and a large amount of nitrogen oxides compounds present in said stream and partial oxidation of the mercury, arsenic, selenium;
  • said wet scrubbing operation including: scrubbing said stream from said dry injection operation;
  • said oxidation operation including: adding an oxidant to said stream subsequent to the said wet scrubbing operation.
  • the wet scrubbing operation and the oxidation operation removing any residual mercury, arsenic, selenium, sulfur oxides, particulate matter and nitrogen oxides compounds remaining in said stream.
  • Suitable oxidants include hydrogen peroxide, potassium permanganate, sodium persulfate, hydroxyl radicals, ozone, NaClO x , where x is 1 through 4, or a combination thereof.
  • the method of this invention further includes the step of recirculating unreacted sorbent to said wet scrubbing operation.
  • the addition amount of the oxidants added into the flue gas or the wet scrubbing solution in the range of 0.8 to 1.5 the stoichiometric requirements to remove all of the SO 2 and NO compounds in the flue gas by converting NO to NO 2 and the SO 2 and SO 3 to SO 4 which then allows them as soluble compounds to be absorbed by the scrubber solution.
  • the said stream from said dry injection process produces sodium or potassium based sulfate, sulfite, fluoride, chloride, nitrite, carbonate and/or nitrate.
  • NO 2 forms, however the plume cannot develop since the NO x and N x O y (where x ⁇ 1 and y ⁇ 2) species are absorbed in the wet scrubber. Accordingly, the previous requirement for auxiliary suppressant addition is obviated.
  • liquid phase oxidants can be used for mercury, arsenic, selenium and NO x removal, such as potassium permanganate (which requires the added maintenance to remove the manganese dioxide, a precipitate that often forms on packing or other surfaces) and sodium hypochlorite (NaOCl) , and sodium persulfate.
  • potassium permanganate which requires the added maintenance to remove the manganese dioxide, a precipitate that often forms on packing or other surfaces
  • sodium hypochlorite NaOCl
  • sodium hypochlorite sodium hypochlorite
  • sodium hypochlorite usually comes in the form of an alkaline solution in order to prevent decomposition of sodium hypochlorite to Cl 2 and Cl 2 O and to result in the optimum oxidizing properties.
  • the optimum pH of that scrubbing solution is about 9, where the oxidizing properties of NaOCl are the best.
  • This pH value is where reaction NaOCl ⁇ NaClO is close to equilibrium and the concentration of NaClO (sodium hypochlorite) which has the tendency to release the active oxygen is maximized.
  • the optimal pH increases with increasing gas contact time.
  • the oxidizing reaction of NO by sodium hypochlorite is as follows:
  • the flue gas is preconditioned by absorbent injection.
  • this can be achieved by wet or dry injection with the sorbent or combinations of sorbent and at any possible location in the system.
  • Dry sodium bicarbonate injection has been found to be particularly effective since it reacts with the sulfur dioxides and trioxides as well as the nitrogen oxides compounds.
  • the sulfur trioxide is managed to a level that is compatible with single stage wet electrostatic precipitators installed in a wet flue gas desulfurization tower.
  • the fifth pollution removal step is possible scrubber modifications to enhance the particulate matter removal in the wet scrubber.
  • Such scrubber modifications for particulate matter might include the addition of a cyclonic spray section, a dynamic scrubber section, introduction of packing and trays which would be co used for further nitrogen oxides and mercury, arsenic, selenium removal or providing orifice scrubber internals.
  • the pollutants are removed primarily through the impaction, diffusion, interception and/or absorption of the pollutant onto droplets of liquid.
  • the liquid containing the pollutant is then collected for disposal. Collection efficiencies for wet scrubbers vary with the particle size distribution of the waste gas stream.
  • Collection efficiency is the highest for all wet scrubbing systems for larger size particles PM 10 and larger, smaller particles less that PM 2.5 often need to have specific scrubber internals to ensure this small diameter particle actually comes in contact with the scrubber solution so that the solution can make contact with particle, absorb the particle and remove the particle from the flue gas.
  • One advantage of the present invention is a sodium or potassium based scrubber is in a complete solution so the system scrubber internals that would plug instantly in the traditional technology calcium slurry based scrubber can be used quite effectivelyin a sodium or potassium based system.
  • Sodium (potassium) based scrubbing systems do not have any solid build up that would plug scrubber internals, calcium based systems do.
  • particulate matter including particulate matter less than or equal to 10 micrometers ( ⁇ m) in aerodynamic diameter (PM10) , particulate matter less than or equal to 2.5 ⁇ m in aerodynamic diameter (PM2.5) .
  • ⁇ m micrometers
  • PM2.5 particulate matter less than or equal to 2.5 ⁇ m in aerodynamic diameter
  • Configurations of Wet Scrubbers form a category of gas-atomized spray scrubbers in which a tube or a duct of some other shape forms the gas-liquid contacting zone.
  • the particle-laden gas stream is forced to pass over the surface of a pool of scrubbing liquid at high velocity, entraining it as droplets as it enters an orifice.
  • the gas stream flowing through the orifice atomizes the entrained liquid droplets in essentially the same manner as a venturi scrubber.
  • the interaction between the PM and atomized liquid droplets also increases.
  • Particulate matter and droplets are then removed from the gas stream by impingement on a series of baffles that the gas stream encounters after exiting the orifice.
  • the collected liquid and PM drain from the baffles back into the liquid pool below the orifice.
  • the scrubbing liquid is fed into the pool at the bottom of the scrubber and later recirculated from the entrainment separator baffles by gravity instead of being circulated by a pump as in venturi scrubbers.
  • Many devices using contactor ducts of various shapes are offered commercially.
  • the principal advantage of this scrubber is the elimination of a pump for recirculation of the scrubbing liquid.
  • a venturi scrubber accelerates the waste gas stream to atomize the scrubbing liquid and to improve gas-liquid contact.
  • a “throat” section is built into the duct that forces the gas stream to accelerate as the duct narrows and then expands.
  • both gas velocity and turbulence increase.
  • the scrubbing liquid is sprayed into the gas stream before the gas encounters the venturi throat, or in the throat, or upwards against the gas flow in the throat.
  • the scrubbing liquid is then atomized into small droplets by the turbulence in the throat and droplet-particle interaction is increased.
  • Some designs use supplemental hydraulically or pneumatically atomized sprays to augment droplet creation.
  • venturi scrubbers generally use the vertical downflow of gas through the venturi throat and incorporate three features: (1) a “wet-approach” or “flooded-wall” entry section to avoid a dust buildup at a wet-dry junction; (2) an adjustable throat for the venturi throat to provide for adjustment of the gas velocity and the pressure drop; and (3) a “flooded” elbow located below the venturi and ahead of the entrainment separator, to reduce wear by abrasive particles.
  • the venturi throat is sometimes fitted with a refractory lining to resist abrasion by dust particles.
  • fiber-bed scrubbers moisture-laden waste gas passes through beds or mats of packing fibers, such as spun glass, fiberglass, or steel. If only mists are to be collected, small fibers may be used, but if solid particles are present, the use of fiber-bed scrubbers is limited by the tendency of the beds to plug.
  • the fiber mats For PM collection, the fiber mats must be composed of coarse fibers and have a high void fraction, to minimize the tendency to plug. The fiber mats are often sprayed with the scrubbing liquid so particles can be collected by deposition on droplets and fibers.
  • the scrubber design may include several fiber mats and an impingement device. The final fiber mat is typically dry for the removal of any droplets which are still entrained in the gas stream.
  • Mechanical scrubbers comprise those devices in which a power-driven rotor produces the fine spray and the contacting of gas and liquid. As in other types of scrubbers, it is the droplets that are the principal collecting bodies for the dust particles. The rotor acts as a turbulence producer. An entrainment separator must be used to prevent carry-over of spray. The simplest commercial devices of this type are essentially fans upon which water is sprayed. Mechanically-aided scrubbers are usually preceded by a cyclone or other pre-cleaner for removal of coarse dust and larger debris. This type of scrubber relies almost exclusively on inertial interception for PM collection, and is capable of high collection efficiencies, but only with commensurate high energy consumption.
  • An impingement-plate scrubber is a vertical chamber with plates mounted horizontally inside a hollow shell. Impingement-plate scrubbers operate as countercurrent PM collection devices. The scrubbing liquid flows down the tower while the gas stream flows upward. Contact between the liquid and the particle-laden gas occurs on the plates. The plates are equipped with openings that allow the gas to pass through. Some plates are perforated or slotted, while more complex plates have valve-like openings.
  • the simplest impingement-plate scrubber is the sieve plate, which has round perforations. In this type of scrubber, the scrubbing liquid flows over the plates and the gas flows up through the holes. The gas velocity prevents the liquid from flowing down through the perforations.
  • Gas-liquid-particle contact is achieved within the froth generated by the gas passing through the liquid layer.
  • Complex plates such as bubble cap or baffle plates, introduce an additional means of collecting PM.
  • the bubble caps and baffles placed above the plate perforations force the gas to turn before escaping the layer of liquid. While the gas turns to avoid the obstacles, most PM cannot and is collected by impaction on the caps or baffles. Bubble caps and the like also prevent liquid from flowing down the perforations if the gas flow is reduced.
  • impingement-plate scrubbers the scrubbing liquid flows across each plate and down the inside of the tower onto the plate below. After the bottom plate, the liquid and collected PM flow out of the bottom of the tower.
  • Impingement-plate scrubbers are usually designed to provide operator access to each tray, making them relatively easy to clean and maintain. Consequently, impingement-plate scrubbers are more suitable for PM collection than packed-bed scrubbers. Particles greater than 1 ⁇ m in aerodynamic diameter can be collected effectively by impingement-plate scrubbers, but many particles ⁇ 1 ⁇ m in aerodynamic diameter will penetrate these devices.
  • Spray scrubbers consist of empty cylindrical or rectangular chambers in which the gas stream is contacted with liquid droplets generated by spray nozzles.
  • a common form is a spray tower, in which the gas flows upward through a bank or successive banks of spray nozzles. Similar arrangements are sometimes used in spray chambers with horizontal gas flow.
  • Such devices have very low gas pressure drops, and all but a small part of the contacting power is derived from the liquid stream. The required contacting power is obtained from an appropriate combination of liquid pressure and flow rate. Physical absorption depends on properties of the gas stream and liquid solvent, such as density and viscosity, as well as specific characteristics of the pollutant (s) in the gas and the liquid stream (e.g., diffusivity, equilibrium solubility) .
  • Condensation scrubbing is a relatively recent development in wet scrubber technology. Most conventional scrubbers rely on the mechanisms of impaction and diffusion to achieve contact between the PM and liquid droplets. In a condensation scrubber, the PM acts as condensation nuclei for the formation of droplets. Generally, condensation scrubbing depends on first establishing saturation conditions in the gas stream. Once saturation is achieved, steam is injected into the gas stream. The steam creates a condition of supersaturation and leads to condensation of water on the fine PM in the gas stream. The large condensed droplets are then removed by one of several conventional devices, such as a high efficiency mist eliminator.
  • each step of the first to fifth step of the method of removing air pollutant from a flue gas stream of the invention are described in detail.
  • it is not essential to use all the five steps or processes for removing air pollutant such as VOC’s, dioxins, mercury, arsenic, selenium, particulates and a host of heavy metals, SOx and NOx etc..
  • air pollutant such as VOC’s, dioxins, mercury, arsenic, selenium, particulates and a host of heavy metals, SOx and NOx etc.
  • only catalytic combustion when adding a chemical additive as a combustion enhancer into the boiler is enough to reduce the formation of particulate matter, sulfur oxides, nitrogen oxides and mercury, arsenic, selenium, VOC’s and dioxins from the flue gas.
  • only adding a fuel conditioning agent to the fuel before feeding into the boiler without any combustion modification chemical can improve the efficiency of an electrostatic precipitator is enough to reduce the formation of particulate matter, sulfur oxides, nitrogen oxides and mercury, arsenic, selenium from the flue gas.
  • SNCR or SCR process is enough to remove air pollutant.
  • the process of catalytic process can preferably be combined with any other steps of the second to fifth step as described for removing air pollutant more efficiently.
  • the process of adding a fuel conditioner agent into the boiler preloaded with a fuel can preferably combined with any steps of the first step, the third step to fifth step as described for removing air pollutant.
  • the denitrification process of SNCR or SCR can preferably be combined with any other step of the first step, the second step, the fourth step and the fifth step for removing air pollutant.
  • the process of catalytic combustion can be preferably combined with the process of adding a fuel conditioning agent, or combined with SNCR or SCR process; or further combined with any scrubbing operation process; any combination thereof, for removing air pollutant, where scrubbing operation process is used, any scrubber internal can be located in the scrubber, such as gas-atomized scrubber, a venture scrubber, a fiber-bed scrubber, a mechanical scrubber with a power-driven rotor, an impingement-plate scrubber, spray scrubber and condensation scrubber etc.
  • two or three or more steps of the first to fifth step or processes can be optionally combined for removing air pollutant of the flue gas.
  • a method of scrubbing particulate matter, mercury, arsenic, selenium, VOC’s, dioxins, sulfur oxides and nitrogen oxides compounds from a flue gas stream characterized in that the method comprises: (I) a process of catalytic combustion operation and (II) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation, and further comprises (III) a process of scrubbing operation, wherein (K) a process of adsorption operation by adsorption device such as an electrostatic precipitator may be after (II) the denitrification process and before (III) the process of scrubbing operation; may be finally carried out after (III) the process of scrubbing operation, preferably carried out before (III) the process of scrubbing operation. Specifically, (III) the process of scrubbing operation. i.e., the fourth step as identified above.
  • the processes set forth herein are useful to reduce the formation and increase the capture air toxics including, as examples: mercury, arsenic, selenium, particulates and a host of heavy metals.
  • the wet scrubbing operation efficiently captures the NO 2 , N 2 O 3 and N 2 O 5 and other N x O y compounds since the conversion of SO 2 to sodium sulfate is not completed in the dry sorbent injection system, so that the presence of sodium sulfite substantially improves the scrubber solution removal of the NO 2 , N 2 O 3 , N 2 O 5 by providing an optimum chemical reaction in addition, at least a portion of the NO is captured by the sodium bicarbonate with the conversion of the NO to nitrogen.
  • the provision of the oxidant augments the effectiveness of the wet scrubbing and in particular, the oxidation of the nitrogen oxides and mercury, arsenic, selenium compounds converting NO to a more soluble NO 2 and elemental mercury, to the soluble oxidized mercury.
  • Figure 1 is a typical schematic for the injection points of the chemical additive used as a combustion enhancer into the boiler.
  • Figure 2 is a typical schematic for a complete system using a selective non-catalytic reduction system for additional nitrogen oxides removal.
  • Figure 3 is a typical schematic for a complete system using a selective catalytic reduction system for additional nitrogen oxides removal.
  • Figure 4 is a typical schematic for a complete system without any additional nitrogen oxides removal.
  • Blower for boiler combustion (exact configuration depends on boiler type or combustion system type)
  • the invention provides several preferable methods as follows:
  • a method of reducing particulate matter, mercury, VOC’s, arsenic, selenium, dioxins, SOx and NOx compounds from a flue gasstream characterized in that the method comprises:
  • Combustion modifications of hydrocarbons using a chemical additive sodium injection into a boiler to enhance particulate matter removal in a downstream electrostatic precipitator, a selective non-catalytic reduction or selective catalytic reduction nitrogen oxides removal system, a dry injection scrubbing operation, a wet scrubbing operation, particulate matter removal enhancements in the wet scrubber and an oxidation scrubbing operation,
  • said chemical additive used as a combustion enhancer shall comprise of manganese, iron, silicon and calcium, aluminum etc.
  • said chemical additive is preferably the mixture of the ingredients of mangenese, iron, silicon and calcium etc. loaded in a carrier of Manganese (II, III) oxide. That is, the chemical additive usually contains Mn 3 O 4 , Fe, SiO 2 , CaO, Al 2 O 3 , S and H 2 O.
  • the chemical additive mainly the elements of Mn, Fe, Si and Ca are the most active ingredients, which functions as enhancing the combustion of the fuel and making the fuel fully combust.
  • said sodium injection into the boiler to improve electrostatic precipitator performance shall be sodium sulfate or sodium carbonate.
  • said dry injection scrubbing operation including:
  • a flue gas stream containing mercury, arsenic, selenium, VOC’s, dioxins particulate matter, sulfur oxides and nitrogen oxides compounds with a sorbent selected from the group consisting of sodium bicarbonate, sodium carbonate, sodium hydroxide, and combinations thereof, for
  • said wet scrubbing operation including:
  • said oxidation operation including:
  • said oxidant is selected from the group consisting of hydrogen peroxide, ozone, potassium permanganate, sodium hypochlorite, sodium chlorite, sodium persulfate, hydroxyl radicals, sodium chlorate, sodium perchlorate or a combination thereof.
  • said stream from said dry injection scrubbing process produces sodium sulfate, sodium sulfite, sodium fluoride, sodium chloride, sodium nitrite, sodium carbonate and/or sodium nitrate.
  • Figure 4 is a typical schematic for a complete system using a selective non-catalytic reduction system for additional nitrogen oxides removal.
  • the method of removing air pollutant of the invention comprises:
  • Coal supplied from silo 1 was burned in a boiler 14. Moreover, a chemical additive can be added into the boiler at the location 2, to speed up desired oxidation reactions of coal or bio-fuels and reduce the formation of undesired products of sulfur dioxide, nitrogen oxides, VOC’s, dioxins, mercury, arsenic, selenium and particulate matter. Blower 12 is connected with the boiler 14 to improve the efficacy of combustion.
  • the chemical additive is a mixture of a refined mineral compound including the metals of iron, manganese, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn3O4) , i.e., a mixture of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn 3 O 4 ) , wherein Mn 3 O 4 is 17-51%by weight Mn, Fe is 5-16 wt. %, SiO 2 2-11%and CaO is3-35 wt. %.
  • the addition amount of the chemical additive is in the range of 100-500grams per tonne coal.
  • Sodium salts like sodium sulfate, sodium bicarbonate, sodium carbonate and sodium hydroxide, or potassium salts like potassium sulfate, potassium bicarbonate, potassium carbonate and potassium hydroxide can mix with the coal before or during combustion in boiler, which can improve the performance of electrostatic precipitator 6, it depends on situations.
  • the collection efficiencies of electrostatic precipitator 6 were enhanced in the range (0.5-1.9%) , leading to reduction in outlet dust concentrations.
  • SO 2 emissions from the boiler 14 increased due to the sulfate addition to the coal.
  • the sodium sulfate addition effectively increased the coal sulfur percent by 0.04%to 1.14%.
  • Potassium sulfate can be used for similar results in particulate matter removal by injecting 0.15 to 0.4 weight percent of potassium sulfate vs coal.
  • SNCR Selective Non-Catalytic Reduction
  • SCR selective catalytic reduction system
  • the flue gas stream was formed in boiler 14. There may or may not be a selective non-catalytic reduction or selective catalytic reduction system (as shown in Figure 5) connection with the boiler 14.
  • a selective non-catalytic reduction or selective catalytic reduction system (as shown in Figure 5) connection with the boiler 14.
  • the flue gas from boiler 14 flows into the SNCR system 4 where the NOx reduction reactions were occurred.
  • the nitrogen oxides can be further reduced.
  • a SCR there is a catalyst in the SCR system to remove NOx, wherein the catalyst may use base metal (lower temperature, primarily vanadium, platinum or titanium) and zeolite (higher temperature) .
  • Flue gas from the SNCR system flows into the next system ESP 6 or a bag house which can further absorb particulate matter and transport the flue gas into the scrubber 8.
  • the flue gas stream from the ESP 6 or a bag house still comprises some waste gas, and can be further removed by injecting sodium bicarbonate, sodium carbonate or sodium hydroxide at location (into a pipeline) 7. During the injection, NO 2 and SO 2 in the flue gas were decreased when detecting at the scrubber inlet.
  • the wet scrubber 8 is connected with the dry injection location 7, and the flue gas can be wet scrubbed through the wet scrubbing solution in scrubber 8. Some modifications on the wet scrubber can enhance the removal of particulate matter, nitrogen oxides and mercury, arsenic, selenium. Sampling flue gas at the scrubber outlet and analyzing its composition to determine the efficacy of wet scrubber 8.
  • the flue gas came out of the wet scrubber can meet the requirement of stringent legislation on air pollution.
  • SCR is used for reducing NO x emission.
  • both SNCR and SCR are not used.
  • Table 1 showed the combustion conditions of boilers.
  • Table 2 showed the analysis of the coal used.
  • Table2 represents the analysis of the coal used.
  • the particulate emission is captured by the bag house connected with Boiler A, sampled and determined, wherein the combustion test is carried out in Boiler A 3 times (No. 1-No. 3) without chemical additive, and 3 times (No. 4-No. 6) with the chemical additive respectively.
  • the results are shown as Table 3.
  • Boiler B was operated on average at 53MW.
  • Boiler A was operated on average at 53MW.
  • Bag house differential pressure was consistent around 1.2kPa at Boiler B and a little higher at 1.4kPa at Boiler A. This reflects the difference in bag operating life between the boilers: Boiler B bags (bag house connected with Boiler B) are new, while Boiler A bags (bag house connected with Boiler A) have completed approximately 36 000 hours of operation.
  • SOx emissions were on average reduced from 796 to 123kg/h, that is by 85%. NOx emissions were similarly reduced by 81%from 34 to 7kg/h by use of the chemical additive.
  • Boiler B SO 2 was reduced by 65%from 3421 mg/Nm 3 to 1197 mg/Nm 3 based on the average SOx concentration, NOx dropped from 127 mg/Nm 3 to 44mg/Nm 3 by 65%based on the average NOx concentration.
  • Boiler C Table 8A and Table 8B showed the combustion conditions of Boiler C.
  • Table 8 and Table 9 showed the combustion result of the coal.
  • the particulate matter, sulfur and nitrogen emission are captured by the bag house connected with Boiler C, then sampled and determined. The results are shown as Table 8C, Table 9 and Table 10.
  • optional combinations of any two or more steps selected from the first step to the fifth step of the method of the invention as said above are used for removing air pollutant of the flue gas, wherein every test is carried out 3 times, the result data is the average of the three test.
  • flue gas from the ESP 6 or bag house flows through location 7 and then if need enters into the wet scrubber 8.
  • the chemical additive in an amount of 0.02wt. %relative to the coal as a fuel, wherein the chemical additive includes 38%Mn, 13%Mg, 11%Fe, and 33%Cu by weight and the remain component is moisture and inevitable impurities.
  • a fuel conditioning agent is used together with the chemical additive, sodium sulfate which is added in 0.09wt. %relative to the coal is used as the conditioning agent.
  • the sodium hypochlorite as the fresh oxidant are used typically with the sodium hypochlorite amount as s stoichiometric ratio to the inlet NO of 1.2 in the tests, specifically NaClO is used in an amount of used 5 kg/hr; in the case of SCR, commercially available vanadium-titanium as the catalyst is used; injecting NaHCO 3 in an amount of 1.56 tons per hour in the dry injection operation at location 7; and a scrubbing solution equivalent to 1 kg of Na 2 CO 3 , 29 kg of Na 2 SO 4 and 19 kg of Na 2 SO 3 dissolved in 187 L of water.
  • the pH of the scrubber solution was about 10.6 in the wet scrubber in some tests to further remove particulate matter, nitrogen oxides and mercury, arsenic, selenium.
  • LSFO which is a comparative test wherein the calcium limestone is used in an amount of 1.00 tons per hour.
  • test Result of optional combination of any two or more steps selected from the first step to the fifth step of the method of the invention is shown as table 11.
  • ESP is electrostatic precipitator for particulate matter removal.
  • SNCR is Selective non-catalytic reduction for Nitrogen oxides removal, wherein ammonia injection was used.
  • SCR is selective catalytic reduction for nitrogen oxides removals
  • LFSO means limestone forced oxidation operation, a calcium based scrubbing system for SO 2 .
  • Wet ESP is a wet electrostatic precipitator for sulfuric acid and PM removal
  • SS Inj sodium sulfate addition to the coal for enhanced electrostatic precipitator performance
  • DSI means dry sorbent injection, i.e., dry injection scrubbing operation utilizing sodium bicarbonate
  • Oxidants means the addition of chemical oxidants
  • Table 11 summarizes the average flue gas compositions at combustor exit of the chimney.
  • oxidant material may be injected into the flue gas duct at any number of locations such as at or approximate the inlet or approximate the outlet.
  • this oxidation step is useful to convert uncaptured NO and NO 2 to be converted to NO 2 , N 2 O 3 , N 2 O 5 and N x O y inter alia.
  • the oxidation steps 48 and 50 are augmented by the injection step with sodium bicarbonate, the injection being broadly denoted by numeral 52.
  • the sodium bicarbonate injection step is preferentially a dry injection step, it will be clearly understood by those skilled in the art that the injection step can also be wet with essentially any alkali compound and at any of several locations from the flue gas duct to the wet scrubber to be discussed hereinafter.
  • Suitable oxidants will be appreciated by those skilled, however, examples include hydrogen peroxide, ozone, sodium chlorate, sodium persulfate, hydroxyl radicals or compounds (NaClO x where x is 1 through 4) or any combination of these materials.
  • the flue gas stream now partially devoid of NO x compounds is treated in a wet to dry transition device 54 and then subsequently on to the wet scrubbing operation in wet scrubber 56.
  • Any suitable scrubber 56 may be incorporated and will be essentially the choice of the designer based on the requirements of the overall circuit.
  • Typical manufactures of wet scrubbers include The Babcock and Wilcox Company, Marsulex, Kawaski Heavy Industries, Mitsui, Chiyoda, Thyssen KEA, inter alia.
  • Numerals 58 and 60 denote further possible oxidant injection points where the aqueous solution of the oxidant is recirculated into the scrubber 56.
  • a suitable pump 62 may be included with each circulation loop of the oxidant.
  • a wet electrostatic precipitator may be introduced into the circuit, where the gas stream is passed through the electrostatic precipitator to polish the flue gas of any further particulate, fine particulates, water droplets or aerosols from the stream. This is an optional step and is not essential to the process.
  • the flue gas can then be discharged through the stack.
  • the wet ESP may or may not be an extension to the wet scrubber.
  • the reactions that occur in the dry injection phase are simply those that involve the sodium bicarbonate contacting the SO x and NO x compounds which would be similar equations if potassium bicarbonate were uses.
  • Exemplary of the actions of the SO x chemistry that occur in the injection apparatus include thefollowing:
  • NO x reactions occurring in the injection phase which include the following:
  • the dry injection operation as well as the wet scrubbing operation are particularly useful in reducing other air toxic compounds present in the flue gas.

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Abstract

A flue gas purification method is provided, which comprises a process of catalytic combustion operation by adding a chemical additive as a combustion enhancer into combustion equipment, in which a fuel such as coal or bio-fuels is combusted. The chemical additive is a mixture of manganese, iron, silicon and calcium loaded in a carrier of manganese (II, III) oxide. The method further comprises adsorption operation, denitrification process through selective non-catalytic reduction or selective catalytic reduction, scrubbing operation or addition of a fuel conditioning agent into the combustion equipment. The method can substantially eliminate sulfur oxides, particulate matter, mercury, arsenic, selenium, VOC's, dioxins, and nitrogen oxides compounds created from the combustion.

Description

FLUE GAS CLEAN UP METHOD USING A MULTIPLE SYSTEM APPROACH Technical field
The present invention relates to a flue gas purification method， and more particularly， the present invention relates to a complete flue gas control system that modifies the combustion characteristics and combines a flue gas purification method incorporating with and without selective non-catalytic reduction or selective catalytic reduction nitrogen oxides reduction techniques， or dry sorbent injection or/and wet scrubbing unit operations with and without chemical oxidants to substantially eliminate sulfur dioxide， sulfur trioxide， particulate matter (PM) ， mercury， arsenic， selenium and nitrogen oxides compounds (NO， NO2， N2O5 etc.) as well as other air toxic compounds such as VOC’s and dioxins from the flue gas created from the combustion of hydrocarbons such as coal or any other fuel.
BACKGROUND ART
In view of new stringent legislation， greater strides have now had to be made concerning fossil fuels. As is well known， the use of fossil fuels significantly contributes to air pollution and a multitude of patents have issued with the objective of mitigating the pollution aspect.
Globally， the prior art establishes a number of wet chemical absorption methods which primarily incorporate wet scrubbers where a hot contaminated gas is scrubbed or detoxified in a gas liquid contact apparatus with a neutralizing solution. The neutralizing solution can typically be any suitable aqueous alkaline liquid or slurry to remove sulfur oxides and other contaminants present in the flue gas stream. The gas liquid contact apparatus are generally employed by power generating stations and use the wet chemical absorption arrangement incorporating sodium， calcium， magnesium， etc. to desulfurize flue gas.
Johnson et al.， in United States Patent No. 6,303,083， issued October 16， 2001， disclose a SOX removal process for flue gas treatment. A specific particle larger than 1 to 2 microns size range for the sorbent is reacted with the flue gas to reduce SO3 content. The treated flue gas is then reacted in a wet scrubber to reduce SO2 content.
Further processes which have been incorporated in industry to remove sulfur trioxide include condensation reactions. An example of such a process is referred to as the WSA-SNOX process. This method involves the catalytic conversion of sulfur dioxide to sulfur trioxide. The sulfur trioxide is then removed by condensation in the form of sulfur acid.
As is evident from the existing flue gas management protocols， NO and NOX formation present complications in terms of plume control. Consequently， the existence of the plume requires additional unit operations and still results in the existence of the plume at tolerable levels.
The wet scrubbing systems that employ lime， limestone， soda ash or other alkaline compositions  demonstrate efficacy for removal of sulfur dioxide， but are significantly less efficient at the removal of sulfur trioxide or sulfuric acid aerosol and have no effect on NO removal. NO is typically 95％of the nitrogen oxides formed during combustion.
In light of the increasing stringent pollution regulations， there clearly exists a need for the management of flue gas where all the various sulfur oxides and nitrogen oxides compounds can be handled effectively without emission of the brown plume of NOx or the blue plume of SO3， the need to augment with suppressants or the combination of equipment which， in the case of the wet flue gas desulfurization and wet electrostatic precipitation， only marginally addresses the problem at a fairly significant expense.
DISCLOSURE OF THE INVENTION
The methodology set forth herein alleviates all of the limitations in the prior art techniques by first reducing the formation of pollutants by systematically removing them by catalytic combustion or adding chemicals additive for combustion enhancement into the boiler， and/or combination SNCR or SCR with optional various scrubbing systems detailed below.
The object of the present invention is to provide an improved method for flue gas pollutant reduction.
According to the present invention， the following technical solutions are provided， wherein the following paragraphs enumerated consecutively from 1 through 64 provide various aspects of the present invention：
1. A method of removing air pollutant from a flue gas stream， characterized in that the method comprises：
(I) a process of catalytic combustion operation：
catalytic combustion operation： adding a chemical additive as a combustion enhancer into a combustion equipment， in which a fuel such as a coal or bio-fuels combust more completely while adding the combustion additive， wherein the additive is a mixture containing the elements of manganese， iron， silicon and calcium loaded in a carrier of Manganese (II， III) oxide， preferably tri-manganese tetroxide (Mn3O4) .
2. The method of paragraph 1， wherein the method further comprises (K) a process of adsorption operation； preferably， the process is performed by an electrostatic precipitator.
3. The method of  paragraph  1 or 2， wherein the method further comprises (II) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation after (I) the process of catalytic combustion operation； preferably， before (K) the process of adsorption operation.
4. The method of any one of paragraphs 1-3， wherein the method further comprises (III) a process of scrubbing operations， wherein (III) the process of scrubbing operations is preferably after (II) the denitrification process.
5. The method of any one of paragraphs 1-4， wherein a fuel conditioning agent is added into the combustion equipment before， after or while adding the chemical additive as a combustion enhancer in the process (I) of catalytic combustion operation.
6. The method of paragraph 5， wherein the fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfite， sodium sulfate， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfite， potassium sulfate， potassium carbonate， potassium bicarbonate and potassium hydroxide.
7. The method of any one of paragraphs 3-6， wherein (II) the denitrification process is the process through selective non-catalytic reduction operation， and an ammonia injection is performed in the temperature range of 900-1050℃or an urea injection is performed in the temperature range of 850-1150℃during selective non catalytic reduction operation.
8. The method of any one of paragraphs 3-6， wherein (II) the denitrification process is the process through selective catalytic reduction operation， wherein vanadium， platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature； preferably， vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430℃during the selective catalytic reduction operation.
9. The method of any one of paragraphs 4-8， wherein (III) the process of scrubbing operations further comprises one or more steps selected from the following steps：
(a) a dry injection scrubbing operation；
(b) a wet scrubbing operation in the wet scrubber； and/or
(c) and/or an oxidation scrubbing operation.
10. The method of paragraph 9， wherein a flue gas stream possibly containing mercury， arsenic， selenium， particulate matter， sulfur oxides and/or nitrogen oxides compounds is contacted with a sorbent selected from the group consisting of sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfate， potassium sulfite， potassium carbonate， potassium bicarbonate， potassium hydroxide， calcium carbonate， calcium bicarbonate， calcium hydroxide， magnesium carbonate， magnesium bicarbonate and magnesium hydroxide， during (a) the step of a dry injection scrubbing operation； wherein the sorbent is preferably one or more selected from the group consisting of sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate and sodium hydroxide.
11. The method of paragraph 10， wherein said stream is further scrubbed in a scrubber during (b) the step of a wet scrubbing operation which is performed after (a) the step of said dry injection scrubbing operation.
12. The method of any one of paragraphs 9-11， wherein an oxidant is added to said stream during (c) the step of an oxidation scrubbing operation； and preferably， (c) the step of an oxidation scrubbing operation is performed after (b) the step of a wet scrubbing operation.
13. The method of any one of paragraphs 9-12， wherein a basic solution comprises one or  more compound selected from sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfate， potassium sulfite， potassium carbonate， potassium bicarbonate and potassium hydroxide； preferably a basic solution comprises one or more compound selected from sodium carbonate， sodium sulfate， and sodium sulfite， more preferably a basic solution with pH 6.5-11， preferably 8.5-11， which predominately comprises a mixture of sodium carbonate， sodium sulfate， sodium sulfite and sodium nitrate， is added in the scrubber during (b) the step of a wet scrubbing operation.
14. The method of  paragraph  12 or 13， wherein the oxidant is one or more selected from the group consisting of hydrogen peroxide， potassium permanganate， sodium persulfate， hydroxyl； radicals， ozone and NaClOx， where x is 1 through 4.
15. The method of any one of paragraphs 4-14， wherein the electrostatic precipitator during (K) the process of adsorption operation is located before a scrubber of (III) the process of scrubbing operations.
16. The method of any one of paragraphs 1-15， wherein said air pollutant include any one material selected from particulate matter， VOC， dioxins， heavy metal such as mercury， arsenic， selenium etc， SOx and NOx compounds and any combination thereof.
17. The method of any one of paragraphs 9-15， wherein (III) the process of scrubbing operations further comprises in sequence the three following steps：
(a) a dry injection scrubbing operation；
(b) a wet scrubbing operation in the wet scrubber；
and (c) and/or an oxidation scrubbing operation.
18. The method of any one of paragraphs 4-14， wherein (K) the process of adsorption operation is performed by an electrostatic precipitator after or before (III) the process of scrubbing operations.
19. The method of any one of paragraphs 2-18， wherein (K) the process of adsorption operation is performed by a bag house or a hot cyclone， or by a scrubber internal located in a scrubber； preferably by any combination of two or more of an electrostatic precipitator， a bag house， a hot cyclone， and a scrubber internal located in a scrubber； more preferably by combination of an electrostatic precipitator with any one or more of a bag house， a hot cyclone， and a scrubber internal located in a scrubber.
20. The method of paragraph 19， wherein a scrubber internal is located in a scrubber for (b) the step of a wet scrubbing operation.
21. A method of removing air pollutant from a flue gas stream， characterized in that the method comprises：
(I) a process of adding a fuel conditioning agent is added into a combustion equipment during combustion operation， in which a fuel such as a coal or bio-fuels are charged before or after or while adding the fuel additive.
22. The method of paragraph 21， wherein the method further comprises (K) a process of adsorption operation， preferably， the process of adsorption operation is performed by an electrostatic precipitator.
23. The method of paragraph 21 or 22， wherein the method further comprises (II) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation after (I) the process of adding a fuel conditioning agent into a combustion equipment； preferably before (K) the process of adsorption operation.
24. The method of any one of paragraphs 21-23， wherein the method further comprises (III) a process of scrubbing operations， wherein (III) the process of scrubbing operations is preferably after (II) the denitrification process.
25. The method of any one of paragraphs 21-24， wherein the fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfite， sodium sulfate， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfite， potassium sulfate， potassium carbonate， potassium bicarbonate and potassium hydroxide.
26. The method of any one of paragraphs 23-25， wherein (II) the denitrification process is the process through selective non catalytic reduction operation， and an ammonia injection is performed in the temperature range of 900-1050℃or an urea injection is performed in the temperature range of 850-1150℃during selective non catalytic reduction operation.
27. The method of any one of paragraphs 23-25， wherein (II) the denitrification process is carried out through selective catalytic reduction operation， wherein vanadium， platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature； preferably， vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430℃during the selective catalytic reduction operation.
28. The method of any one of paragraphs 24-27， wherein (III) the process of scrubbing operations further comprises one or more steps selected from the following steps：
(a) a dry injection scrubbing operation；
(b) a wet scrubbing operation in the wet scrubber； and/or
(c) and/or an oxidation scrubbing operation.
29. The method of any one of paragraphs 28， wherein a flue gas stream， containing mercury， arsenic， selenium， particulate matter， VOC’s， dioxins， sulfur oxides and nitrogen oxides compounds， is contacted with a sorbent selected from the group consisting of sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfate， potassium sulfite， potassium carbonate， potassium bicarbonate， potassium hydroxide， calcium carbonate， calcium bicarbonate， calcium hydroxide， magnesium carbonate， magnesium bicarbonate and magnesium hydroxide， during (a) the step of a dry injection scrubbing operation； wherein the sorbent is preferably selected from the group consisting of sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide.
30. The method of paragraph 29， wherein said stream is further scrubbed in a scrubber during (b) the step of a wet scrubbing operation which is performed after (a) the step of said dry injection scrubbing operation.
31. The method of any one of paragraphs 28-30， wherein an oxidant is added to said stream during (c) the step of an oxidation scrubbing operation； and preferably， (c) the step of an oxidation scrubbing operation is performed after (b) the step of a wet scrubbing operation.
32. The method of any one of paragraphs 28-31， wherein a basic solution comprises one or more compound selected from sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfate， potassium sulfite， potassium carbonate， potassium bicarbonate and potassium hydroxide； preferably a basic solution comprises one or more compound selected from sodium carbonate， sodium sulfate， and sodium sulfite； more preferably a basic solution with pH 6.5-11， preferably 8.5-11 which predominately comprises a mixture of sodium carbonate， sodium sulfate， and sodium nitrate， is added in the scrubber during (b) the step of a wet scrubbing operation.
33. The method of paragraph 31 or paragraph 32 wherein the oxidant is selected from the group consisting of hydrogen peroxide， potassium permanganate， sodium persulfate， hydroxyl radicals， sodium persulfate， ozone， NaClOx， where x is 1 through 4.
34. The method of any one of paragraphs 24-33， wherein the electrostatic precipitator during (K) the process of adsorption operation is located before a scrubber of (III) the process of scrubbing operations.
35. The method of any one of paragraphs 21-34， wherein said air pollutant include any one material selected from particulate matter， VOC’s ， dioxins， heavy metal such as mercury， arsenic， selenium， SOx and NOx compounds and any combination thereof.
36. The method of any one of paragraphs 28-35， wherein (III) the process of scrubbing operations further comprises in sequence the three following steps：
(a) a dry injection scrubbing operation；
(b) a wet scrubbing operation in the wet scrubber；
and (c) and/or an oxidation scrubbing operation.
37. The method of any one of paragraphs 24-33， wherein (K) the process of adsorption operation is performed by an electrostatic precipitator after or before (III) a process of scrubbing operations.
38. The method of any one of paragraphs 22-37， wherein (K) the process of adsorption operation is performed by a bag house or a hot cyclone， or by a scrubber internal located in a scrubber for a wet scrubbing operation； preferably by any combination of two or more of an electrostatic precipitator， a bag house， a hot cyclone， and a scrubber internal located in a scrubber for a wet scrubbing operation； more preferably by combination of an electrostatic precipitator with any one or more of an electrostatic precipitator， a bag house， a hot cyclone， and a scrubber internal  located in a scrubber for a wet scrubbing operation.
39. The method of paragraph， 38， wherein a scrubber internal is located in a scrubber for (b) the step of a wet scrubbing operation.
40. A method of removing air pollutant from a flue gas stream， characterized in that the method comprises：
(1) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation and (K) a process of adsorption operation.
41. The method of paragraph 40， wherein (K) the process of adsorption operation is performed by an electrostatic precipitator.
42. The method of paragraph 41 or 42， wherein the method further comprises (2) a process of scrubbing operations after (1) the denitrification process.
43. The method of any one of paragraphs 40-42， wherein (1) the denitrification process is the process through selective non-catalytic reduction operation， and an ammonia injection is performed in the temperature range of 900-1050℃or an urea injection is performed in the temperature range of 850-1150℃during selective non catalytic reduction operation.
44. The method of any one of paragraphs 40-42， wherein (1) the denitrification process is the process through selective catalytic reduction operation， wherein vanadium， platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature； preferably， vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430℃during the selective catalytic reduction operation.
45. The method of any one of paragraphs 42-44， wherein (2) the process of scrubbing operations further comprises one or more steps selected from the following steps：
(a) a dry injection scrubbing operation；
(b) a wet scrubbing operation in the wet scrubber and/or
(c) and/or an oxidation scrubbing operation.
46. The method of paragraph 45， wherein a flue gas stream containing mercury， arsenic， selenium， particulate matter， VOC’s ， dioxins， sulfur oxides and nitrogen oxides compounds is contacted with a sorbent selected from the group consisting of sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfate， potassium sulfite， potassium carbonate， potassium bicarbonate， potassium hydroxide， calcium carbonate， calcium bicarbonate， calcium hydroxide， magnesium carbonate， magnesium bicarbonate and magnesium hydroxide， during (a) the step of a dry injection scrubbing operation； wherein the sorbent is preferably selected from the group consisting of sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide.
47. The method of paragraphs46， wherein said stream is scrubbed in a scrubber during (b) the step of a wet scrubbing operation which is performed after (a) the step of said dry injection scrubbing operation.
48. The method of any one of paragraphs 45-47， wherein an oxidant is added to said stream during (c) the step of an oxidation scrubbing operation； and preferably， (c) the step of an oxidation scrubbing operation is performed after (b) the step of a wet scrubbing operation.
49. The method of any one of paragraphs 45-48， wherein a basic solution comprises one or more compound selected from sodium sulfate， sodium sulfite， sodium carbonate， sodium bicarbonate， sodium hydroxide， potassium sulfate， potassium sulfite， potassium carbonate， potassium bicarbonate and potassium hydroxide； preferably a basic solution comprises one or more compound selected from sodium carbonate， sodium sulfate， and sodium sulfite； more preferably a basic solution with pH 6.5-11， preferably 8.5-11 which predominately comprises a mixture of sodium carbonate， sodium sulfate， and sodium nitrate， is added in the scrubber during (b) the step of a wet scrubbing operation.
50. The method of paragraph 48 or 49， wherein the oxidant is selected from the group consisting of hydrogen peroxide， potassium permanganate， sodium persulfate， hydroxyl radicals， ozone， NaClOx， where x is 1 through 4.
51. The method of any one of paragraphs 42-50， wherein the electrostatic precipitator during (K) the process of adsorption operation is located before a scrubber of (2) the process of scrubbing operations.
52. The method of any one of paragraphs 40-51， wherein said air pollutant include any one material selected from particulate matter， VOC， dioxins， heavy metal such as mercury， arsenic， selenium， SOx and NOx compounds and any combination thereof.
53. The method of any one of paragraphs 42-52， wherein (2) the process of scrubbing operations further comprises in sequence the three following steps：
(a) a dry injection scrubbing operation；
(b) a wet scrubbing operation (particulate matter removal enhancements) in the wet scrubber；
and (c) and/or an oxidation scrubbing operation.
54. The method of any one of paragraphs 41-53， wherein (K) the process of adsorption operation is performed by an electrostatic precipitator after or before (2) a process of scrubbing operations.
55. The method of any one of paragraphs 41-54， wherein (K) the process of adsorption operation is performed by a bag house or a hot cyclone， or by a scrubber internal located in a scrubber for a wet scrubbing operation； preferably by any combination of two or more of an electrostatic precipitator， a bag house a hot cyclone， and a scrubber internal located in a scrubber for a wet scrubbing operation； more preferably by combination of an electrostatic precipitator with any one or more of an electrostatic precipitator， a bag house， a hot cyclone， and a scrubber internal located in a scrubber for a wet scrubbing operation.
56. The method of paragraph 55， wherein a scrubber internal is located in a scrubber for (b) the  step of a wet scrubbing operation.
57. The method of any one of paragraphs 1-56， wherein the fuel conditioning agent is added into the fuel before feeding to the boiler.
58. The method of any one of paragraphs 1-57， wherein the fuel conditioning agent is added into the fuel in 0.08-1 weight ％， preferably 0.09-0.8 weight ％of a weight ratio of the fuel conditioning agent to the fuel， preferably， the sodium sulfate as fuel conditioning agent is added into the coal in 0.09-0.6 weight ％of a weight ratio of the fuel conditioning agent to the coal； more preferably， the sodium sulfate as fuel conditioning agent is added into the coal in 0.1-0.3 weight％of a weight ratio of the fuel conditioning agent to the coal.
59. The method of any one of paragraphs 1-58， wherein the chemical additive added into the fuel combustion equipment in 0.01-0.05 weight ％of a weight ratio of the fuel； preferably， the chemical additive is a mixture of manganese， iron， silicon and calcium loaded in a carrier of Manganese (II， III) oxide， preferably tri-manganese tetroxide (Mn3O4) ； more preferably， the chemical additive includes Mn3O4 17-51wt％ of Manganese， Fe 5-16wt. ％， CaO 3-35 wt. ％and SiO2 2-11％.
In a preferable embodiment， for the chemical additive， it comprises Mn3O4 20-48％. by weight of Mn， Fe 8-14 wt. ％， CaO 10-35 wt. ％and SiO2 5-10％； In an more preferably embodiments， for the chemical additive， it comprises Mn3O4 40-51wt％Mn， Fe 11-16 wt. ％， CaO 17-33 wt. ％and SiO2 5-11％.
60. The method of any of the paragraphs 1-59， wherein the amount of chemical absorbent injected into the flue gas during the step of dry injection operation is injected into the flue gas in the range of 0.8 to 1.5 the stoichiometric requirements to remove all of the SOx and NOx compounds in the flue gas.
61. A method of conditioning the PM collection efficiency of an electrostatic precipitator， wherein a fuel conditioning agent is added into the fuel before or during combustion of a fuel.
62. The method of paragraph 61， wherein the fuel conditioning agent is added into the fuel in 0.08-1 weight ％ of the fuel conditioning agent to the fuel， preferably， the sodium sulfate as fuel conditioning agent is added into the coal in 0.09-0.6 weight ％ of the fuel conditioning agent to the coal； more preferably， the sodium sulfate as fuel conditioning agent is added into the coal in 0.1-0.3 weight ％ of a weight ratio of the fuel conditioning agent to the coal.
63. The method of paragraph 61 or 62， wherein the PM collection efficiency of an electrostatic precipitator is enhanced in the range of 0.5-1.9％.
64. The method of any one of paragraphs 1-63， wherein an addition amount of the oxidants during (c) the step of oxidation scrubbing operation is in the range of 0.8 to 1.5 stoichiometric requirements to ultimately remove all of the SO2 and NO compounds in the flue gas.
Specifically， in one preferable embodiments， according to the present invention there is provided a method of reducing the formation of particulate matter， sulfur oxides， nitrogen oxides and mercury， arsenic， selenium and then scrubbing the particulate matter， mercury， arsenic， selenium， sulfur  oxides and nitrogen oxides compounds from a flue gas stream， characterized in that the method comprises： primarily catalytic combustion to speed up desired oxidation reactions of coal or bio-fuels， so as to reduce the formation of undesired products of sulfur dioxide， nitrogen oxides， mercury， arsenic， selenium and particulate matter； sodium sulfate injection into the boiler， to reduce particulate matter escaping from PM absorption device such as the electrostatic precipitator etc.， a selective non-catalytic reduction system and/or a selective catalytic reduction system for further nitrogen oxides reduction， a dry injection scrubbing operation， and/or a wet scrubbing operation which may or may not include specific scrubber internals for enhanced particulate matter removal and possibly an oxidation scrubbing operation for advanced NO and mercury， arsenic， selenium control. Said dry injection operation includes injection of sodium or potassium compounds into the boiler combustion system， contacting a flue gas stream containing sulfur oxides and nitrogen oxides， mercury， arsenic， selenium compounds and particulate matter with a sorbent selected from the group consisting of sodium bicarbonate， sodium carbonate， sodium hydroxide， potassium bicarbonate， potassium carbonate， potassium hydroxide and combinations thereof， for removing substantially all of the sulfur oxides， mercury， arsenic， selenium and a large amount of nitrogen oxides compounds present in said stream； said wet scrubbing operation includes： scrubbing said stream from said dry injection scrubbing operation； and said oxidation operation includes： adding an oxidant to said flue gas stream subsequent to said wet scrubbing operation， the wet scrubbing operation and the oxidation operation removing any residual mercury， arsenic， selenium， particulate matter， sulfur oxides and nitrogen oxides compounds remaining in said flue gas stream. Suitable oxidants include hydrogen peroxide， ozone， potassium permanganate， sodium persulfate， hydroxyl radicals， NaClOx， where x is 1 through 4， or a combination thereof all used in specific pH regimes by the addition of acids or NaOH. Optionally， the method of this invention further includes the step of recirculating unreacted sorbent to said wet scrubbing operation. With the method of this invention， typically said stream from said dry injection process produces sodium sulfate， sodium sulfite， sodium fluoride， sodium chloride， sodium nitrate， sodium nitrite， sodium carbonate， and all the potassium compounds of potassium sulfate， potassium sulfite， potassium fluoride， potassium chloride， potassium nitrate， potassium nitrate， and potassium carbonate.
Specifically， of importance in any system for complete economics is the prevention of pollutants. This present invention reduced the formation of the pollutants firstly by the addition of a catalytic combustion chemical process to speed up desired oxidation reactions of coal or bio-fuels so as to reduce the formation of undesired products， especially particulate matter， nitrogen oxides， carbon dioxide， mercury， arsenic， selenium and sulfur oxides far below what can be achieved without chemical additives. The most important attributes are： fuel oxidation to release more heat energy and reduce coal usage which naturally results in the reduction of nitrogen oxides， mercury， arsenic， selenium， particulate matter and sulfur oxides into the flue gas thus reducing emissions of these dangerous pollutants into the air， the destruction of other pollutant gases， re- burning of CO in the flue gas. Most hydrocarbons are consumed in the optimized combustion process thus reducing particulate emissions considerably. Lower temperature combustion also burns out the normal black acid smut emissions through the smoke stack which reduces the soot. The chemical additive usually causes tars and hydrocarbons to burn out more completely releasing oxygen at the point of combustion， which changes and manipulates the base/acid ratio， so doing increases the ash fusion temperature. The chemical additive also improves the combustion which means drier and softer more friable build-up in the boiler which results in longer periods between shut downs and an easier cleaning with high pressure water. In boilers or other combustion equipment using this chemical additive more carbon is burned at a given excess air level and the potential exists for not only lower air levels to be used but for instance lowering of the coal bed in grate boilers thus savings on fuel use will be obtained. Therefore， herein， a chemical additive is also named catalyst and said catalytic combustion means the combustion of a fuel in the presence of a fuel additive. The weight ratio of a chemical additive to a fuel is not a special requirement. Preferably， the addition amount of a chemical additive is enough to arrive at the complete combustion of the fuel. Generally， when the fuel is a coal， the weight ratio of a chemical additive to the coal is in the range of 100 grams to 500 grams per tonne of coal. This all takes place without the chemical additive being consumed or altered in its chemical form after the reaction is complete. The combustion chemical additive is a highly refined mineral compound including manganese， iron， magnesium， calcium， etc， with the main ingredient manganese (Mn3O4) . The chemical additive the chemical additive includes Mn3O4 17-51wt. ％of Mn， Fe 5-16 wt. ％， CaO 3-35wt. ％and SiO2 2-11％， the rest is moisture and various minor compounds that comes with the main ore. The chemical additive can be obtained by mixing all the ingredients of the ore MnO2， MnO， Fe， SiO2 and CaO， and heating them through a common firing method (at the temperature of 800-1500℃) so as to make Fe， Si， Ca， Al loaded in Mn3O4. In fact， the sum of the weight percentage of all the components is 100weight％. The chemical additive usually contains Mn3O4， Fe， SiO2， CaO， Al2O3， S and H2O. In the chemical additive， mainly the element of Mn， Fe， Si and Ca are the most active ingredients， which functions as enhancing the combustion of the fuel making the fuel more fully combust. In fact， for the present invention， the chemical additive can be obtained through all kinds of common methods as long as the obtained chemical compound or composition includes the above-identified ingredients Mn， Fe， SiO2 and CaO， other ingredients such as any one substance or element selected from Al， Mg， K， Ti， Ba， P and S and H2O， may be mixed into the chemical additive as impurities， wherein Mn3O4 can be obtained by heating a mixture of MnO2 and MnO through firing method at the temperature of above 1000℃. Herein， the content of Mn3O4 is calculated based on Mn， that is， the content of Mn3O4 does not consider the content of the element of oxgen in the compound of Mn3O4； Similarly， the content of SiO2 is calculated based on Si， that is， the content of SiO2 does not consider the content of the element of oxgen in the compound of SiO2 ； the content of CaO is calculated based on Ca， that is， the content of CaO does not consider the  content of the element of oxygen in the compound of CaO.
The chemical additive is non-toxic， non-poisonous， non-combustible and non-chemical based. In the presence of carbon and oxygen the chemical additive reacts to increase/improve the combustion rate. At the same time the chemical additive lowers the temperature at which the reactions will occur. This in itself avoids low temp evaporation and stops the escape of hydrocarbons as is usual， and rather burning them out to avoid sticky wet attachment to the inside of the boiler. In a preferable embodiment， the chemical additive preferably contains the following ingredients by weight： Mn 51％， Fe 16％， Si 11％， Ca 17％， Al2O3 1％， S 0.5％， H2O 3.5％. In one preferable embodiment， the chemical additive (Mn3O4/Iron/Silicon/Calcium， wherein Mn3O4 is a carrier， Mn， Fe， Si and Ca are loaded in the carrier) including Mn 44％， Fe 11％， Si 7％and Calcium 33％by weight.
Manganese (II， III) oxide is the chemical compound that is the carrier chemical in this chemical additive with formula Mn3O4 and is present in two+2and+3and the formula is sometimes written as MnO·Mn2O3. Mn3O4 is found in nature as the mineral Mn3O4 formed when any manganese oxide is heated in air above 1000℃. Considerable research has centered on producing nano-crystalline Mn3O4 and various syntheses that involve oxidation of Mn II or reduction of Mn VI. Mn3O4 has been found to act as a catalyst for a range of reactions e.g. the oxidation of methane and carbon monoxide； the decomposition of NO.
The second pollutant removal step after the combustion modifications using the chemical additive， is the addition of a fuel conditioner into the boiler or other combustion equipment to improve the electrostatic precipitator performance. Fuel conditioning produced by sodium sulfite， sodium sulfate， sodium carbonate， sodium bicarbonate or sodium hydroxide； or potassium sulfite， potassium sulfate， potassium carbonate， potassium bicarbonate or potassium hydroxide addition to the coal supply provides an effective means of improving the performance of a hot-side electrostatic precipitator which has undergone sodium or potassium depletion， because of the high resistivity pattern of performance deterioration. The electrostatic precipitator performance improvement can be explained as an equilibrium process in the depleted zone in which sodium (potassium) is transported to the depleted region by a thermally induced chemical diffusion process. The reduction of ash resistivity appears to depend upon the equilibrium which is attained between the competing chemical and electrical transport processes. The equilibrium point， in turn， depends upon ash composition and certain design and operating parameters of the electrostatic precipitator. Emissions standards are becoming more stringer， as a result new retrofit/techniques are being applied in the existing power plants. Electrostatic Precipitators (ESP) are used typically to control fly ash emitting from the boilers in power plants. The coal burned in power plants to generate the power are often characterized by low calorific value (3500-4500) Kcal/Kg.， and high ash content (35-45) ％. Thus compared to  metallurgical coals， this coal generates about 6 to 7 times more ash for collection for similar electricity generation and the low sulfur content results in the resistivity of fly ash being 100-1000 times higher than that generated elsewhere. Thus ESPs， despite being much larger， have lower collection efficiencies. One method which we have met with success， is the coal ash conditioning with sodium or potassium salt before feeding to boiler.
The particle collection efficiency of an electrostatic precipitator (ESP) for a coal-fired power-plant flue-gas cleaning depends to a large extent on the electrical properties of the fly ash. Flue gas conditioning with sodium or potassium refers to the addition of sodium or potassium based chemicals to the flue gas for modification of fly ash properties and/or electrical conditions in the ESP to improve the collection efficiency of ESPs. There are several methods for upgrad-ing ESP performance： (1) adding collector plate area to the existing ESP to overcome poor performance； (2) using a wet ESP； (3) increasing or lowering the gas temperature in the ESP； and (4) adding sodium or potassium chemicals to modify the fly ash or the electrical conditions in the ESP. For older ESPs， flue gas conditioning with sodium or potassium chemicals is often the most cost effective way to upgrade performance.
Fuel conditioning agents influence the ESP collection efficiency through one or more of the following mechanisms： (1) adsorbing on the surface of fly ash to reduce surface resistivity； (2) adsorbing on the fly ash to change the adhesion and cohesion properties of the ash； (3) increasing ultrafine particle concentrations for space charge enhancement； (4) increasing the electrical breakdown strength of the flue gas， (5) increasing the mean particle size； and (6) changing the acid dew point in the flue gas. Ash resistivity is indirectly related to the alkali content in the ash， and reduction of ash resistivity by increasing the alkali concentration was tried. Sodium chloride has been tried in the laboratory and found to be effective. However， it is not recommended because it can lead to corrosion of metal equipment. A sodium or potassium based conditioning agent will affect some or all of these factors. The ash resistivity is important because it can affect both (1) and (2) above.
The mechanism for fuel conditioning depends on how the sodium or potassium is applied. If a sodium or potassium compound is injected into the boiler along with coal， it will decompose and the sodium (potassium) is bound in the ash. The sodium (potassium) will increase the conductivity and lower the ash resistivity in the same way as natural sodium and if a sulfate compound is used it will effectively increase the sulfur content of the coal. Care has to be taken to ensure the sodium or potassium sulfate is effectively and uniformly bound to the coal and that can be achieved in a commercial plant by slightly wetting the coal before spraying dry sodium or potassium sulfate onto the coal.
If the sodium or potassium alkali compound is co-precipitated with the ash， the compound trapped in the space between the particles on the dust layer offers an additional conductive path for charge dissipation.
Fuel conditioning， unlike with other conditioning agents， is not limited to cold-side ESPs. It can be added to the boiler along with coal. It can be applied either in solution or dry powder form. The most important parameter which affects its effectiveness is the mixing of the alkali salt and the fly ash. Generally， the adding amount of a fuel conditioning agent into a fuel is in the range of 1-10kg per tonne fuel when an agent is mixed with a fuel. Said fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfate， sodium carbonate， sodium bicarbonate and sodium hydroxide， potassium sulfate， potassium carbonate， potassium bicarbonate， or potassium hydroxide. Specifically， when said fuel conditioning agent is sodium sulfate， the adding amount of sodium sulfate into a fuel is preferably in the range of 1-3kg per tonne coal； when said fuel conditioning agent is sodium bicarbonate， the adding amount of sodium bicarbonate into a coal is preferably in the range of 2-6kg per tonne coal； when said fuel conditioning agent is sodium carbonate， the adding amount of sodium carbonate into a coal is preferably in the range of 1-3kg per tonne coal； when said fuel conditioning agent is sodium hydroxide， the adding amount of sodium hydroxide into a coal is preferably in the range of 0.52-1.65kg per tonne coal. Sodium compounds are more often used due to the preferred pricing over the similar potassium substances.
To be effective， the sodium must be either incorporated into all the ash particles or co-precipitated with the ash on the ESP plates so it yields well-mixed deposits.
The conditioning test on the electrostatic precipitator operating characteristics
Specifically， in the invention the function of fuel conditioning agent on conditioning the electrostatic precipitator operating characteristics is determined by the following test.
Sodium Preconditioning the Coal
Research Program
The overall objectives of the research program were as follows：
Evaluation of the effectiveness of boiler injection of sodium compounds for improving precipitator performance.
Evaluation of the effect of boiler injection of sodium compounds at a range of dosages to determine boiler operating and electrostatic precipitator operating characteristics.
Sodium Addition System
Sodium sulfate was tested to streamline the results.
The sodium sulfate by-product was delivered from the silo to the coal feeder belt by a screw feeder at a rate ranging from 0.08 to1 weight％sodium sulfate to a coal， preferably， from 0.09 to 0.6 weight％sodium sulfate to a coal； more preferably， from 0.1 to 0.3 weight％sodium sulfate to a coal.
The following observations were made based on the results of our tests： There was a reduction in outlet dust concentration when the sodium salt was mixed with coal being fed to the boiler in all cases. Certain sulfur depleted coal were assumed to be more effective when fuel conditioning was  present but we did not have the ability to test a multitude of coal types. The PM emission levels were reduced from base line levels in all cases. The collection efficiencies of electrostatic precipitator were enhanced in the range of (0.5-1.9) ％， there by leading to reduction in outlet dust concentrations. The electrical resistivity reduced from the base line conditions at operating temperatures of the ESP. The enhancement of the collection effectives of electrostatic precipitator can be attributed to drastic reduction in electrical resistivity’s of fly ash due to fuel conditioning. There was no long term detrimental effect of the sodium addition to the coal to the boiler. SO2 emissions from the boiler increased due to the sulfate addition to the coal. The sodium sulfate addition effectively increased the coal sulfur percent by 0.04％to 0.14％. This did not mean completely transforming into sulfur oxides conversion as some of the additional sulfur from the sodium sulfate remained in the fly ash.
The third pollution removal step may or may not be the use of a selective non-catalytic reduction or selective catalytic reduction system. The selective non-catalytic reduction or selective catalytic reduction systems could work in conjunction with the coal chemical additive used as a combustion enhancer and in certain cases using traditional low nitrogen oxides combustion burners selective non-catalytic reduction or selective catalytic reduction might not be needed for compliance with current nitrogen oxides regulations. Additionally， there will be situations wherein the client has in place selective non-catalytic reduction or selective catalytic reduction systems and they will be in use for the integrated pollution control system. The selection of a selective catalytic reduction or a selective non-catalytic reduction in conjunction with the coal fuel additive， and dry sorbent injection system plus chemical oxidants will be based on nitrogen oxides pollution requirements and economics.
Selective Catalytic Reduction (SCR)
SCR is a process that involves post-combustion removal of NOx from flue gas with a catalytic reactor. In the SCR process， ammonia injected into the exhaust gas reacts with nitrogen oxides and oxygen to form nitrogen and water. The reactions take place on the surface of a catalyst bed. The function of the catalyst is to effectively lower the activation energy of the NOx decomposition reaction. Technical factors related to this technology include the catalyst reactor design， optimum operating temperature， sulfur content of the fuel， catalyst de-activation due to aging or poisoning， ammonia slip emissions， and design of the ammonia injection system. The SCR system is comprised of a number of subsystems. These include the SCR reactor and flues， ammonia injection system and ammonia storage and delivery system. The SCR reactor with necessary inlet and outlet duct work is located downstream of the economizer and upstream of the air heater and the particulate control system. From the economizer outlet， the flue gas will first pass through a low-pressure ammonia/air injection grid designed to provide optimal mixing of ammonia with flue gas. The ammonia treated flue gas will then flow through the catalyst bed and exit to the air heater.
The SCR system for a pulverized coal boiler typically utilizes a fixed bed catalyst in a vertical down flow multi-stage reactor. The reactor will include a seal system to prevent gas from bypassing  the catalyst bed. The reactor will contain multiple stages of catalyst beds with room for loading future stages. For each stage， a soot blowing system is provided.
Reduction catalysts are divided into two groups： base metal (lower temperature， primarily vanadium， platinum or titanium) and zeolite (higher temperature) . Both groups exhibit advantages and disadvantages in terms of operating temperature， reducing agent/NOx ratio， and optimum oxygen concentration. A disadvantage common to base metal catalysts is the narrow range of temperatures in which the reactions will proceed. Platinum group catalysts have the advantage of requiring lower ignition temperature， but have been shown to also have a lower maximum operating temperature. Operating above the maximum temperature results in oxidation of ammonia to either nitrogen oxides (thereby actually increasing NOx emissions) or ammonium nitrate.
Optimum operating temperature for a vanadium-titanium catalyst system has been shown to be in the range of 280 to 430 ℃， which is significantly higher than for platinum catalyst systems. However， the vanadium-titanium catalyst systems begin to break down when continuously operating at temperatures above this range. Consequently， operating above the maximum temperature for the catalyst system again results in the oxidation of ammonia to either nitrogen oxides (increasing NOx emissions) or ammonium nitrate.
Sulfur content of the fuel can be a concern for systems that employ SCR. Catalyst systems promote partial oxidation of sulfur dioxide to sulfur trioxide (SO3) ， which combines with water vapor to form sulfuric acid. At typical SCR operating temperatures， SO3 and sulfuric acid react with excess ammonia to form ammonium salts. These ammonium salts may condense as the flue gases are cooled and can lead to increased uncontrolled emissions of PM10 entering the particulate collector. Fouling may eventually lead to decreased NOx reduction performance； increased system pressure drop over time and decreased heat transfer efficiencies. The present invention will eliminate this concern since the dry sorbent injection system will remove the SO3 created from the catalyst bed reaction.
The SCR process is subject to catalyst deactivation over time. Catalyst deactivation occurs through two primary mechanisms： physical deactivation and chemical poisoning. Physical deactivation is generally the result either of prolonged exposure to excessive temperatures or masking of the catalyst due to entrainment of particulate from ambient air or internal contaminants. Chemical poisoning is caused by the irreversible reaction of the catalyst with a contaminant in the gas stream and is a permanent condition. Catalyst suppliers typically only guarantee a limited lifetime to very low emission level， high performance catalyst systems.
SCR manufacturers typically estimate 10 part per million volumetric dry (ppmvd) of unreacted ammonia emissions (ammonia slip) when making guarantees at very high efficiency levels. To achieve high NOx reduction rates， SCR vendors suggest a higher ammonia injection rate than stoichiometrically required， which conversely results in ammonia slip. Thus an emissions trade-off between NOx and ammonia may occur in high NOx reduction applications.
The potential environmental impacts associated with the use of SCR include：
· Unreacted ammonia would be emitted to the atmosphere (ammonia slip) .
· Ammonium salts would increase loading to the particulate collection stage as PM10 (and PM2.5) .
· Safety issues and Risk Management Planning may be required relative to the transportation， handling， and storage of ammonia (aqueous or anhydrous) .
The present invention alleviates all of the downstream issues caused by SCR operations.
Selective Non-Catalytic Reduction (SNCR)
The SNCR process is based on a gas-phase homogeneous reaction， within a specified temperature range， between NOx in the flue gas and either injected NH3 or urea to produce gaseous nitrogen and water vapor. SNCR systems do not employ a catalyst bed； the NOx reduction reactions are driven by the thermal decomposition of ammonia and the subsequent reduction of NOx. Consequently， the SNCR process operates at higher temperatures than the SCR process.
Critical to the successful reduction of NOx with SNCR is the temperature of the flue gas at the point where the reagent is injected. For the ammonia injection process， the necessary temperature range is 900-1,050℃； for the urea injection process the nominal temperature range is 850-1,150℃. Also critical to effective application of these processes are gas mixing， residence time at temperature， and ammonia slip.
Theoretically， one mole of ammonia (or one-half mole of urea) will react with one mole of NOx， forming elemental nitrogen and water. In reality however， not all the injected reagent will react due to imperfect mixing， uneven temperature distribution， and insufficient residence time. These physical limitations may be compensated for by injecting a large amount of excess reagent and essentially achieving low NOx emissions at the expense of emissions of unreacted reagent， referred to as ammonia slip. These emissions represent an adverse environmental impact and can lead to formation of ammonium salts and may contribute to regional haze as a precursor to PM2.5. Thus， for a given boiler configuration， there is a limit on the degree of NOx reduction which can be achieved with SNCR while maintaining acceptable levels of ammonia slip.
Pulverized coal-fired units have a limited furnace temperature window and poor lateral mixing， conditions which render SNCR less effective in these units. SNCR has been applied to pulverized coal boilers more often to achieve 30-50％ reductions since the technology can be retrofit more easily than other add-on controls. Due to mixing limitations and a brief temperature window in which to react， SNCR is fundamentally less effective at controlling NOx from boilers as compared with other combustion processes.
The present invention alleviates all of the concerns with SNCR operations.
The fourth pollution removal step is a scrubbing operation including one or more steps of a dry  injection operation， a wet scrubbing operation in a scrubber and/or an oxidation scrubbing operation. Preferably， the scrubbing operation is unification of the dry injection pollution removal operation and a wet scrubbing operation with or without chemical oxidants. This works effectively and advantageously eliminates the concern for NOx brown plume， SO3 emissions with the associated blue plume， and ammonia slip. Previously， reaction of the sodium sorbents resulted in the synthesis of nitrogen oxides compounds as plume if the dry injection of sodium bicarbonate was collected in a bag house or electrostatic precipitator. The nitrogen oxides compounds are soluble species and are easily managed by treatment with the wet scrubbing operation.
Wherein， a dry injection pollution removal operation， a wet scrubbing operation and an oxidation operation，
wherein said dry injection scrubbing operation including：
contacting a flue gas stream containing mercury， arsenic， selenium， particulate matter， sulfur oxides and nitrogen oxides compounds with a sorbent selected from the group consisting of sodium bicarbonate， sodium carbonate， sodium hydroxide， or the potassium based compounds and combinations thereof， for removing substantially all of the sulfur oxides and a large amount of nitrogen oxides compounds present in said stream and partial oxidation of the mercury， arsenic， selenium；
said wet scrubbing operation including： scrubbing said stream from said dry injection operation；
and said oxidation operation including： adding an oxidant to said stream subsequent to the said wet scrubbing operation.
Specifically， the wet scrubbing operation and the oxidation operation removing any residual mercury， arsenic， selenium， sulfur oxides， particulate matter and nitrogen oxides compounds remaining in said stream.
Suitable oxidants include hydrogen peroxide， potassium permanganate， sodium persulfate， hydroxyl radicals， ozone， NaClOx， where x is 1 through 4， or a combination thereof. Optionally， the method of this invention further includes the step of recirculating unreacted sorbent to said wet scrubbing operation. The addition amount of the oxidants added into the flue gas or the wet scrubbing solution in the range of 0.8 to 1.5 the stoichiometric requirements to remove all of the SO2 and NO compounds in the flue gas by converting NO to NO2 and the SO2 and SO3 to SO4 which then allows them as soluble compounds to be absorbed by the scrubber solution.
With the method of this invention， typically the said stream from said dry injection process produces sodium or potassium based sulfate， sulfite， fluoride， chloride， nitrite， carbonate and/or nitrate. NO2 forms， however the plume cannot develop since the NOx and NxOy (where x≥1 and y≥2) species are absorbed in the wet scrubber. Accordingly， the previous requirement for  auxiliary suppressant addition is obviated.
Several liquid phase oxidants can be used for mercury， arsenic， selenium and NOx removal， such as potassium permanganate (which requires the added maintenance to remove the manganese dioxide， a precipitate that often forms on packing or other surfaces) and sodium hypochlorite (NaOCl) ， and sodium persulfate. Practically speaking， the most economical of the oxidizing agents is sodium hypochlorite， though the products with hydrogen peroxide are more valuable. Sodium hypochlorite usually comes in the form of an alkaline solution in order to prevent decomposition of sodium hypochlorite to Cl2 and Cl2O and to result in the optimum oxidizing properties. The optimum pH of that scrubbing solution is about 9， where the oxidizing properties of NaOCl are the best. This pH value is where reaction NaOCl→NaClO is close to equilibrium and the concentration of NaClO (sodium hypochlorite) which has the tendency to release the active oxygen is maximized. The optimal pH increases with increasing gas contact time. The oxidizing reaction of NO by sodium hypochlorite is as follows：
NO + NaClO→NaCl + NO2.
The problem with sodium hypochlorite in practical applications is the addition of chloride ion (Cl-) to the process. This Cl- has an effect on the effluent properties and increased the potential for corrosion in the materials of construction. Also， the formation of sodium chloride (NaCl) in the recirculation sump will require a constant bleed-off stream or blow-down to maintain the NaCl in solution and therebyprevent “salting-out” in the process.
The oxidants listed on Table A are a partial list of used for NOx capture：
Figure PCTCN2017097804-appb-000001
In the combined system set forth herein， the flue gas is preconditioned by absorbent injection.  Advantageously， this can be achieved by wet or dry injection with the sorbent or combinations of sorbent and at any possible location in the system. Dry sodium bicarbonate injection has been found to be particularly effective since it reacts with the sulfur dioxides and trioxides as well as the nitrogen oxides compounds. Generally speaking， the sulfur trioxide is managed to a level that is compatible with single stage wet electrostatic precipitators installed in a wet flue gas desulfurization tower.
The fifth pollution removal step is possible scrubber modifications to enhance the particulate matter removal in the wet scrubber. Such scrubber modifications for particulate matter might include the addition of a cyclonic spray section， a dynamic scrubber section， introduction of packing and trays which would be co used for further nitrogen oxides and mercury， arsenic， selenium removal or providing orifice scrubber internals. The pollutants are removed primarily through the impaction， diffusion， interception and/or absorption of the pollutant onto droplets of liquid. The liquid containing the pollutant is then collected for disposal. Collection efficiencies for wet scrubbers vary with the particle size distribution of the waste gas stream. Collection efficiency is the highest for all wet scrubbing systems for larger size particles PM 10 and larger， smaller particles less that PM 2.5 often need to have specific scrubber internals to ensure this small diameter particle actually comes in contact with the scrubber solution so that the solution can make contact with particle， absorb the particle and remove the particle from the flue gas. One advantage of the present invention is a sodium or potassium based scrubber is in a complete solution so the system scrubber internals that would plug instantly in the traditional technology calcium slurry based scrubber can be used quite effectivelyin a sodium or potassium based system. Sodium (potassium) based scrubbing systems do not have any solid build up that would plug scrubber internals， calcium based systems do.
The following many types of scrubbers internals can be used to control particulate matter (PM) ， including particulate matter less than or equal to 10 micrometers (μm) in aerodynamic diameter (PM10) ， particulate matter less than or equal to 2.5 μm in aerodynamic diameter (PM2.5) . Specifically， detailed description is as follows.
Configurations of Wet Scrubbers form a category of gas-atomized spray scrubbers in which a tube or a duct of some other shape forms the gas-liquid contacting zone. The particle-laden gas stream is forced to pass over the surface of a pool of scrubbing liquid at high velocity， entraining it as droplets as it enters an orifice. The gas stream flowing through the orifice atomizes the entrained liquid droplets in essentially the same manner as a venturi scrubber. As the gas velocity and turbulence increases with the passing of the gas through the narrow orifice， the interaction between the PM and atomized liquid droplets also increases. Particulate matter and droplets are then removed from the gas stream by impingement on a series of baffles that the gas stream encounters after exiting the orifice. The collected liquid and PM drain from the baffles back into the liquid pool below the orifice. The scrubbing liquid is fed into the pool at the bottom of the scrubber and later recirculated from the entrainment separator baffles by gravity instead of being circulated by a pump  as in venturi scrubbers. Many devices using contactor ducts of various shapes are offered commercially. The principal advantage of this scrubber is the elimination of a pump for recirculation of the scrubbing liquid.
A venturi scrubber accelerates the waste gas stream to atomize the scrubbing liquid and to improve gas-liquid contact. In a venturi scrubber， a “throat” section is built into the duct that forces the gas stream to accelerate as the duct narrows and then expands. As the gas enters the venturi throat， both gas velocity and turbulence increase. Depending upon the scrubber design， the scrubbing liquid is sprayed into the gas stream before the gas encounters the venturi throat， or in the throat， or upwards against the gas flow in the throat. The scrubbing liquid is then atomized into small droplets by the turbulence in the throat and droplet-particle interaction is increased. Some designs use supplemental hydraulically or pneumatically atomized sprays to augment droplet creation. The disadvantage of these designs is that clean liquid feed is required to avoid clogging. After the throat section， the mixture decelerates， and further impacts occur causing the droplets to agglomerate. Once the particles have been captured by the liquid， the wetted PM and excess liquid droplets are separated from the gas stream by an entrainment section which usually consists of a cyclonic separator and/or a mist eliminator. Current designs for venturi scrubbers generally use the vertical downflow of gas through the venturi throat and incorporate three features： (1) a “wet-approach” or “flooded-wall” entry section to avoid a dust buildup at a wet-dry junction； (2) an adjustable throat for the venturi throat to provide for adjustment of the gas velocity and the pressure drop； and (3) a “flooded” elbow located below the venturi and ahead of the entrainment separator， to reduce wear by abrasive particles. The venturi throat is sometimes fitted with a refractory lining to resist abrasion by dust particles.
In fiber-bed scrubbers， moisture-laden waste gas passes through beds or mats of packing fibers， such as spun glass， fiberglass， or steel. If only mists are to be collected， small fibers may be used， but if solid particles are present， the use of fiber-bed scrubbers is limited by the tendency of the beds to plug. For PM collection， the fiber mats must be composed of coarse fibers and have a high void fraction， to minimize the tendency to plug. The fiber mats are often sprayed with the scrubbing liquid so particles can be collected by deposition on droplets and fibers. For PM removal， the scrubber design may include several fiber mats and an impingement device. The final fiber mat is typically dry for the removal of any droplets which are still entrained in the gas stream.
Mechanical scrubbers comprise those devices in which a power-driven rotor produces the fine spray and the contacting of gas and liquid. As in other types of scrubbers， it is the droplets that are the principal collecting bodies for the dust particles. The rotor acts as a turbulence producer. An entrainment separator must be used to prevent carry-over of spray. The simplest commercial devices of this type are essentially fans upon which water is sprayed. Mechanically-aided scrubbers are usually preceded by a cyclone or other pre-cleaner for removal of coarse dust and larger debris. This type of scrubber relies almost exclusively on inertial interception for PM collection， and is  capable of high collection efficiencies， but only with commensurate high energy consumption.
An impingement-plate scrubber is a vertical chamber with plates mounted horizontally inside a hollow shell. Impingement-plate scrubbers operate as countercurrent PM collection devices. The scrubbing liquid flows down the tower while the gas stream flows upward. Contact between the liquid and the particle-laden gas occurs on the plates. The plates are equipped with openings that allow the gas to pass through. Some plates are perforated or slotted， while more complex plates have valve-like openings. The simplest impingement-plate scrubber is the sieve plate， which has round perforations. In this type of scrubber， the scrubbing liquid flows over the plates and the gas flows up through the holes. The gas velocity prevents the liquid from flowing down through the perforations.
Gas-liquid-particle contact is achieved within the froth generated by the gas passing through the liquid layer. Complex plates， such as bubble cap or baffle plates， introduce an additional means of collecting PM. The bubble caps and baffles placed above the plate perforations force the gas to turn before escaping the layer of liquid. While the gas turns to avoid the obstacles， most PM cannot and is collected by impaction on the caps or baffles. Bubble caps and the like also prevent liquid from flowing down the perforations if the gas flow is reduced. In all types of impingement-plate scrubbers， the scrubbing liquid flows across each plate and down the inside of the tower onto the plate below. After the bottom plate， the liquid and collected PM flow out of the bottom of the tower.
Impingement-plate scrubbers are usually designed to provide operator access to each tray， making them relatively easy to clean and maintain. Consequently， impingement-plate scrubbers are more suitable for PM collection than packed-bed scrubbers. Particles greater than 1 μm in aerodynamic diameter can be collected effectively by impingement-plate scrubbers， but many particles ＜1 μm in aerodynamic diameter will penetrate these devices.
Spray scrubbers consist of empty cylindrical or rectangular chambers in which the gas stream is contacted with liquid droplets generated by spray nozzles. A common form is a spray tower， in which the gas flows upward through a bank or successive banks of spray nozzles. Similar arrangements are sometimes used in spray chambers with horizontal gas flow. Such devices have very low gas pressure drops， and all but a small part of the contacting power is derived from the liquid stream. The required contacting power is obtained from an appropriate combination of liquid pressure and flow rate. Physical absorption depends on properties of the gas stream and liquid solvent， such as density and viscosity， as well as specific characteristics of the pollutant (s) in the gas and the liquid stream (e.g.， diffusivity， equilibrium solubility) . These properties are temperature dependent， and lower temperatures generally favor absorption of gases by the solvent. Absorption is also enhanced by greater contacting surface， higher liquid-gas ratios， and higher concentrations in the gas stream. Chemical absorption may be limited by the rate of reaction， although the rate-limiting step is typically the physical absorption rate， not the chemical reaction rate.
Condensation scrubbing is a relatively recent development in wet scrubber technology. Most  conventional scrubbers rely on the mechanisms of impaction and diffusion to achieve contact between the PM and liquid droplets. In a condensation scrubber， the PM acts as condensation nuclei for the formation of droplets. Generally， condensation scrubbing depends on first establishing saturation conditions in the gas stream. Once saturation is achieved， steam is injected into the gas stream. The steam creates a condition of supersaturation and leads to condensation of water on the fine PM in the gas stream. The large condensed droplets are then removed by one of several conventional devices， such as a high efficiency mist eliminator.
Each step of the first to fifth step of the method of removing air pollutant from a flue gas stream of the invention are described in detail. In the invention， it is not essential to use all the five steps or processes for removing air pollutant such as VOC’s， dioxins， mercury， arsenic， selenium， particulates and a host of heavy metals， SOx and NOx etc.. In fact， it depends on specific flue gas and circumstances. That is， according to different fuel or different flue gas or characteristics of PM adsorption devices， it is enough to just use a part of the five steps for removing air pollutant. In one embodiment， only catalytic combustion when adding a chemical additive as a combustion enhancer into the boiler is enough to reduce the formation of particulate matter， sulfur oxides， nitrogen oxides and mercury， arsenic， selenium， VOC’s and dioxins from the flue gas. In one embodiment， only adding a fuel conditioning agent to the fuel before feeding into the boiler without any combustion modification chemical can improve the efficiency of an electrostatic precipitator is enough to reduce the formation of particulate matter， sulfur oxides， nitrogen oxides and mercury， arsenic， selenium from the flue gas. In one embodiment， SNCR or SCR process is enough to remove air pollutant. In one embodiment， the process of catalytic process can preferably be combined with any other steps of the second to fifth step as described for removing air pollutant more efficiently. In one embodiment， the process of adding a fuel conditioner agent into the boiler preloaded with a fuel can preferably combined with any steps of the first step， the third step to fifth step as described for removing air pollutant. In one embodiment， the denitrification process of SNCR or SCR can preferably be combined with any other step of the first step， the second step， the fourth step and the fifth step for removing air pollutant. In one embodiment， the process of catalytic combustion can be preferably combined with the process of adding a fuel conditioning agent， or combined with SNCR or SCR process； or further combined with any scrubbing operation process； any combination thereof， for removing air pollutant， where scrubbing operation process is used， any scrubber internal can be located in the scrubber， such as gas-atomized scrubber， a venture scrubber， a fiber-bed scrubber， a mechanical scrubber with a power-driven rotor， an impingement-plate scrubber， spray scrubber and condensation scrubber etc.. In a summary， two or three or more steps of the first to fifth step or processes can be optionally combined for removing air pollutant of the flue gas.
In another preferable embodiment of the invention， there is provided a method of scrubbing particulate matter， mercury， arsenic， selenium， VOC’s， dioxins， sulfur oxides and nitrogen oxides compounds from a flue gas stream， characterized in that the method comprises： (I) a process of  catalytic combustion operation and (II) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation， and further comprises (III) a process of scrubbing operation， wherein (K) a process of adsorption operation by adsorption device such as an electrostatic precipitator may be after (II) the denitrification process and before (III) the process of scrubbing operation； may be finally carried out after (III) the process of scrubbing operation， preferably carried out before (III) the process of scrubbing operation. Specifically， (III) the process of scrubbing operation. i.e.， the fourth step as identified above.
As a particular benefit， the processes set forth herein are useful to reduce the formation and increase the capture air toxics including， as examples： mercury， arsenic， selenium， particulates and a host of heavy metals.
As set forth herein previously， prior art attempts relating to the conversion of NO2 were problematic since a brown plume of NO2 was not captured by downstream equipment. By the combination of the technology set forth herein， the wet scrubbing operation efficiently captures the NO2， N2O3 and N2O5 and other NxOy compounds since the conversion of SO2 to sodium sulfate is not completed in the dry sorbent injection system， so that the presence of sodium sulfite substantially improves the scrubber solution removal of the NO2， N2O3， N2O5 by providing an optimum chemical reaction in addition， at least a portion of the NO is captured by the sodium bicarbonate with the conversion of the NO to nitrogen.
The provision of the oxidant augments the effectiveness of the wet scrubbing and in particular， the oxidation of the nitrogen oxides and mercury， arsenic， selenium compounds converting NO to a more soluble NO2 and elemental mercury， to the soluble oxidized mercury.
Brief description of the drawings
Figure 1 is a typical schematic for the injection points of the chemical additive used as a combustion enhancer into the boiler.
Figure 2 is a typical schematic for a complete system using a selective non-catalytic reduction system for additional nitrogen oxides removal.
Figure 3 is a typical schematic for a complete system using a selective catalytic reduction system for additional nitrogen oxides removal.
Figure 4 is a typical schematic for a complete system without any additional nitrogen oxides removal.
Wherein the numbers in Figures 2-4 have the meanings as follows：
1. Coal supply
2. Chemical additive (combustion enhancer) injection into boiler
3. Sodium or potassium sulfate， bicarbonate， carbonate， hydroxide mixing with coal for electrostatic precipitator performance improvement
4. Selective non-catalytic reduction
5. Bottom ash from boiler
6. Electrostatic precipitator
7. Dry sorbent injection with sodium or potassium bicarbonate
8. Wet sodium or potassium carbonate scrubber with or without scrubber internals for additional particulate matter removal， section of the scrubber used for SO2 pick up as well as NO2 pick up.
9. Steam turbine or use of steam produced by boiler
10. Airborne sodium or potassium bicarbonate /fertilizer production plant
11. Stack
12. Blower for boiler combustion (exact configuration depends on boiler type or combustion system type)
13. Oxidant supply to scrubber
14. Boiler or combustion equipment (kiln etc) for coal burning
15. Packing and spray layer in scrubber for chemical oxidants
16. Sodium (potassium) sulfate and nitrate return from scrubber
17. Spent and recycle oxidant return
18. Ammonium bicarbonate or ammonia and carbon dioxide addition to the sodium /potassium bicarbonate /fertilizer production plant
19. Electrical generator
20. Electricity
21. Fertilizer produced by Airborne sodium /potassium bicarbonate /fertilizer production plant
It will be noted that throughout the appended drawings， like features are identified by like reference numerals.
MODE FOR CARRYING OUT THE INVENTIONS
Specifically， the invention provides several preferable methods as follows：
A method of reducing particulate matter， mercury， VOC’s， arsenic， selenium， dioxins， SOx and NOx compounds from a flue gasstream， characterized in that the method comprises：
Combustion modifications of hydrocarbons using a chemical additive， sodium injection into a boiler to enhance particulate matter removal in a downstream electrostatic precipitator， a selective non-catalytic reduction or selective catalytic reduction nitrogen oxides removal system， a dry injection scrubbing operation， a wet scrubbing operation， particulate matter removal enhancements in the wet scrubber and an oxidation scrubbing operation，
said chemical additive used as a combustion enhancer shall comprise of manganese， iron， silicon and calcium， aluminum etc. Specifically， said chemical additive is preferably the mixture of  the ingredients of mangenese， iron， silicon and calcium etc. loaded in a carrier of Manganese (II， III) oxide. That is， the chemical additive usually contains Mn3O4， Fe， SiO2， CaO， Al2O3， S and H2O. In the chemical additive， mainly the elements of Mn， Fe， Si and Ca are the most active ingredients， which functions as enhancing the combustion of the fuel and making the fuel fully combust.
said sodium injection into the boiler to improve electrostatic precipitator performance shall be sodium sulfate or sodium carbonate.
said dry injection scrubbing operation including：
contacting a flue gas stream containing mercury， arsenic， selenium， VOC’s， dioxins particulate matter， sulfur oxides and nitrogen oxides compounds with a sorbent selected from the group consisting of sodium bicarbonate， sodium carbonate， sodium hydroxide， and combinations thereof， for
removing substantially all of the sulfur oxides and a large amount of nitrogen oxides compounds present in said stream and preconditioning the mercury， arsenic， selenium for later removal in the wet scrubber；
said wet scrubbing operation including：
scrubbing said stream from said dry injection scrubbing operation； and
said particulate matter removal in the scrubber
said oxidation operation including：
adding an oxidant to said stream subsequent to said wet scrubbing operation，
the wet scrubbing operation and the oxidation operation removing any residual SOX and NOX compounds remaining in said stream.
Preferably， in the method， wherein said oxidant is selected from the group consisting of hydrogen peroxide， ozone， potassium permanganate， sodium hypochlorite， sodium chlorite， sodium persulfate， hydroxyl radicals， sodium chlorate， sodium perchlorate or a combination thereof.
Preferably， in the method， further including the step of recirculating unreacted sorbent to said wet scrubbing operation.
Preferably， in the method， wherein said stream from said dry injection scrubbing process produces sodium sulfate， sodium sulfite， sodium fluoride， sodium chloride， sodium nitrite， sodium carbonate and/or sodium nitrate.
The detailed description of the process of the invention according to one embodiment is made based on Figures 4-7 as follows.
Figure 4 is a typical schematic for a complete system using a selective non-catalytic reduction system for additional nitrogen oxides removal. As shown in Figure 4， the method of removing air pollutant of the invention comprises：
1) Catalytic Combustion with a chemical additive
Coal supplied from silo 1 was burned in a boiler 14. Moreover， a chemical additive can be added  into the boiler at the location 2， to speed up desired oxidation reactions of coal or bio-fuels and reduce the formation of undesired products of sulfur dioxide， nitrogen oxides， VOC’s， dioxins， mercury， arsenic， selenium and particulate matter. Blower 12 is connected with the boiler 14 to improve the efficacy of combustion.
Wherein the chemical additive is a mixture of a refined mineral compound including the metals of iron， manganese， silicon and calcium loaded in a carrier of Manganese (II， III) oxide， preferably tri-manganese tetroxide (Mn3O4) ， i.e.， a mixture of manganese， iron， silicon and calcium loaded in a carrier of Manganese (II， III) oxide， preferably tri-manganese tetroxide (Mn3O4) ， wherein Mn3O4 is 17-51％by weight Mn， Fe is 5-16 wt. ％， SiO2 2-11％and CaO is3-35 wt. ％. Preferably， the addition amount of the chemical additive is in the range of 100-500grams per tonne coal.
2) Sodium salt or potassium salt addition as a conditioning agent
Sodium salts like sodium sulfate， sodium bicarbonate， sodium carbonate and sodium hydroxide， or potassium salts like potassium sulfate， potassium bicarbonate， potassium carbonate and potassium hydroxide can mix with the coal before or during combustion in boiler， which can improve the performance of electrostatic precipitator 6， it depends on situations. The collection efficiencies of electrostatic precipitator 6 were enhanced in the range (0.5-1.9％) ， leading to reduction in outlet dust concentrations. SO2 emissions from the boiler 14 increased due to the sulfate addition to the coal. The sodium sulfate addition effectively increased the coal sulfur percent by 0.04％to 1.14％. Potassium sulfate can be used for similar results in particulate matter removal by injecting 0.15 to 0.4 weight percent of potassium sulfate vs coal. 3) Selective Non-Catalytic Reduction (SNCR) or selective catalytic reduction system (SCR)
After the combustion， the flue gas stream was formed in boiler 14. There may or may not be a selective non-catalytic reduction or selective catalytic reduction system (as shown in Figure 5) connection with the boiler 14. When using a SNCR system， the flue gas from boiler 14 flows into the SNCR system 4 where the NOx reduction reactions were occurred. As a result， the nitrogen oxides can be further reduced. As for a SCR， there is a catalyst in the SCR system to remove NOx， wherein the catalyst may use base metal (lower temperature， primarily vanadium， platinum or titanium) and zeolite (higher temperature) .
4) Electrostatic precipitator (ESP) or bag house
Flue gas from the SNCR system flows into the next system ESP 6 or a bag house which can further absorb particulate matter and transport the flue gas into the scrubber 8.
There are several methods for upgrading ESP performance： (1) adding collector plate area to the existing ESP to overcome poor performance； (2) using a wet ESP； (3) increasing or lowering the gas temperature in the ESP； and (4) adding sodium chemicals to modify the fly ash or the electrical conditions in the ESP. For older ESPs， flue gas conditioning with sodium chemicals is often the most cost effective way to upgrade performance.
5) Dry injection scrubbing and wet scrubber
The flue gas stream from the ESP 6 or a bag house still comprises some waste gas， and can be further removed by injecting sodium bicarbonate， sodium carbonate or sodium hydroxide at location (into a pipeline) 7. During the injection， NO2 and SO2 in the flue gas were decreased when detecting at the scrubber inlet.
The wet scrubber 8 is connected with the dry injection location 7， and the flue gas can be wet scrubbed through the wet scrubbing solution in scrubber 8. Some modifications on the wet scrubber can enhance the removal of particulate matter， nitrogen oxides and mercury， arsenic， selenium. Sampling flue gas at the scrubber outlet and analyzing its composition to determine the efficacy of wet scrubber 8.
6) Oxidation operation
There is a packing and spray layer 15 in the wet scrubber 8， where can add chemical oxidants. Any remained SOx and NOx can be oxidized to a more soluble compound， so as to enhance the removal of SOx and NOx.
After some or all the operations above， the flue gas came out of the wet scrubber can meet the requirement of stringent legislation on air pollution.
As shown in Figure 5， SCR is used for reducing NOx emission. As shown in Figure 6， both SNCR and SCR are not used.
As shown in Figure 7， specific details of the dry injection system， the NO2 removal before the chemical oxidants and the NO to NO2 conversion with the oxidants and the NO2 pick up with oxidants are made.
Examples below are used to describe the method or devices of our invention.
Example 1： Chemical additive Combustion Test
In order to test the effect of chemical additive， said chemical additive combustion was done as follows：
Adding coal into the boiler 14， then adding 0.02％or 0.03％weight (relative to the weight of coal) of the chemical additive (Mn3O4/Iron/Silicon/Calcium， wherein Mn3O4 is a carrier， Mn， Fe， Si and Ca are loaded in the carrier) including 44％Mn， 11％Iron， 7 Si％and 33％Calcium by weight wherein the remain component is moisture and inevitable impurities (the chemical additive used in the boilers A， B and C) at location 2. The comparison experiment was done without fuel additive. Sampling flue gas from the bag house connected with a boiler to determine the particulate emission， SO2 emission and NOx emission.
Chemical additive Combustion Test 1
Table 1 showed the combustion conditions of boilers. Table 2 showed the analysis of the coal  used.
Table 1 Combustion conditions of boilers
Figure PCTCN2017097804-appb-000002
Table2 represents the analysis of the coal used.
Figure PCTCN2017097804-appb-000003
The results of the test work are as follows：
Boiler A：
The particulate emission is captured by the bag house connected with Boiler A， sampled and determined， wherein the combustion test is carried out in Boiler A 3 times (No. 1-No. 3) without chemical additive， and 3 times (No. 4-No. 6) with the chemical additive respectively. The results are shown as Table 3.
Table 3 Particulate emission test results in Boiler A
Figure PCTCN2017097804-appb-000004
Sulfur oxides test results in Boiler A are shown as Table 4.
Table 4 Sulfur oxides test results in Boiler A
Figure PCTCN2017097804-appb-000005
Nitrogen oxides test results in boiler A are shown as Table 5.
Table 5 Nitrogen oxides test results in Boiler A
Figure PCTCN2017097804-appb-000006
Boiler B：
The sulfur and nitrogen emission are captured by the bag house connected with Boiler B， then sampled and determined， wherein the combustion test is carried out in Boiler B (No. 1-No. 3) with the chemical additive 3 times， and without the chemical additive times (No. 1-No. 3) respectively. The results are shown as Table 6 and Table 7.
Table 6. Sulfur oxides test results in Boiler B
Figure PCTCN2017097804-appb-000007
Table 7. Nitrogen oxides test results in Boiler B
Figure PCTCN2017097804-appb-000008
General boiler and bag house operation was normal over the test period. Boiler B was operated on average at 53MW. Boiler A was operated on average at 53MW. Bag house differential pressure was consistent around 1.2kPa at Boiler B and a little higher at 1.4kPa at Boiler A. This reflects the difference in bag operating life between the boilers： Boiler B bags (bag house connected with Boiler B) are new， while Boiler A bags (bag house connected with Boiler A) have completed approximately 36 000 hours of operation.
It can be seen from the results above that：
Chemical additive usage reduced gaseous emissions significantly：
As for Boiler A， SOx emissions were on average reduced from 796 to 123kg/h， that is by 85％. NOx emissions were similarly reduced by 81％from 34 to 7kg/h by use of the chemical additive.
As for Boiler B， SO2 was reduced by 65％from 3421 mg/Nm3 to 1197 mg/Nm3 based on the average SOx concentration， NOx dropped from 127 mg/Nm3 to 44mg/Nm3 by 65％based on the average NOx concentration.
Chemical additive Combustion Test 2
Boiler C： Table 8A and Table 8B showed the combustion conditions of Boiler C. Table 8 and Table 9 showed the combustion result of the coal.
Table 8A Combustion Conditions on Boiler C
  Boiler C
Power 5MW
Pressure 1.3kPa
Temperature Average 175℃
chemical additive M3O4/Mg/Fe/Cu
Amount of chemical additive 0.03％
Table 8B Conditions on Boiler C
Figure PCTCN2017097804-appb-000009
The particulate matter， sulfur and nitrogen emission are captured by the bag house connected with Boiler C， then sampled and determined. The results are shown as Table 8C， Table 9 and Table 10.
Table 8C. Emission Test Results in Boiler C without Chemical Additive
Figure PCTCN2017097804-appb-000010
Table 9. Emission Test results in Boiler C with Chemical Additive
Figure PCTCN2017097804-appb-000011
As for Boiler C， a summary of those results were：
1. The total particulate matter reduced from 84,897 mg/Nm3 to 28,035mg/Nm3；
2. SO2 was reduced from 409 down to 156 mg/Nm3 (down by 63％)
3. NOx dropped from 156.86 mg/nm3 to 150.28 mg/Nm3
4. CO2 remained at 7.31 in both tests.
Example 2
In the example， optional combinations of any two or more steps selected from the first step to the fifth step of the method of the invention as said above are used for removing air pollutant of the flue gas， wherein every test is carried out 3 times， the result data is the average of the three test.
Specifically， during all the tests， flue gas from the ESP 6 or bag house flows through location 7 and then if need enters into the wet scrubber 8. The chemical additive in an amount of 0.02wt. ％relative to the coal as a fuel， wherein the chemical additive includes 38％Mn， 13％Mg， 11％Fe， and 33％Cu by weight and the remain component is moisture and inevitable impurities. When a fuel conditioning agent is used together with the chemical additive， sodium sulfate which is added in 0.09wt. ％relative to the coal is used as the conditioning agent. If needed the sodium hypochlorite as the fresh oxidant are used typically with the sodium hypochlorite amount as s stoichiometric ratio to the inlet NO of 1.2 in the tests， specifically NaClO is used in an amount of used 5 kg/hr； in the case of SCR， commercially available vanadium-titanium as the catalyst is used； injecting NaHCO3 in an amount of 1.56 tons per hour in the dry injection operation at location 7； and a scrubbing solution equivalent to 1 kg of Na2CO3， 29 kg of Na2SO4 and 19 kg of Na2SO3 dissolved in 187 L of water. The pH of the scrubber solution was about 10.6 in the wet scrubber in some tests to further remove particulate matter， nitrogen oxides and mercury， arsenic， selenium. Besides， in the test using LSFO， which is a comparative test wherein the calcium limestone is used in an amount of 1.00 tons per hour.
Sampling 3 times in the flue gas and testing the average flue gas compositions at an exit of stack， wherein the flue gas volumetric flow is 384， 780 Nm3/hr， 144.1 ℃ and moving at 3.3 m/s.
Table 10 Conditions Common to All Tests
Figure PCTCN2017097804-appb-000012
Finally， test Result of optional combination of any two or more steps selected from the first step to the fifth step of the method of the invention is shown as table 11.
Figure PCTCN2017097804-appb-000013
Figure PCTCN2017097804-appb-000014
Note：
ESP is electrostatic precipitator for particulate matter removal.
SNCR is Selective non-catalytic reduction for Nitrogen oxides removal， wherein ammonia injection was used.
SCR is selective catalytic reduction for nitrogen oxides removals
LFSO means limestone forced oxidation operation， a calcium based scrubbing system for SO2.
Wet ESP is a wet electrostatic precipitator for sulfuric acid and PM removal
SS Inj means sodium sulfate addition to the coal for enhanced electrostatic precipitator performance
DSI means dry sorbent injection， i.e.， dry injection scrubbing operation utilizing sodium bicarbonate
Wet scrub is wet sodium carbonate scrubbing
Oxidants means the addition of chemical oxidants
PM Mod’s means that the scrubber internal modification devices for additional particulate matter removal
Table 11 summarizes the average flue gas compositions at combustor exit of the chimney.
It can be seen from Table 11 that the particulate matter， mercury， arsenic， selenium， SOx and NOx compounds from a flue gas stream can be removed efficiently by any combination of the first step to the fifth step of the invention.
Herein， the whole of the PCT application WO 2004/030797A1， which is the present inventor’s technology， is incorporated into the present application. It can be seen from the test result of the PCT application WO 2004/030797A1 that the scrubber was very effective in removing NO2 produced in the flue stream after the injection of NaHCO3. The scrubber was also very effective at removing SO2.
In an attempt to further increase the efficiency of the overall system， oxidant material may be injected into the flue gas duct at any number of locations such as at or approximate the inlet or approximate the outlet. At this oxidation step， is useful to convert uncaptured NO and NO2 to be converted to NO2， N2O3， N2O5 and NxOy inter alia. The oxidation steps 48 and 50 are augmented by the injection step with sodium bicarbonate， the injection being broadly denoted by numeral 52. Although the sodium bicarbonate injection step is preferentially a dry injection step， it will be clearly understood by those skilled in the art that the injection step can also be wet with essentially any alkali compound and at any of several locations from the flue gas duct to the wet scrubber to be discussed hereinafter.
Suitable oxidants will be appreciated by those skilled， however， examples include hydrogen  peroxide， ozone， sodium chlorate， sodium persulfate， hydroxyl radicals or compounds (NaClOx where x is 1 through 4) or any combination of these materials. Once having been treated with a dry injection step， the flue gas stream now partially devoid of NOx compounds is treated in a wet to dry transition device 54 and then subsequently on to the wet scrubbing operation in wet scrubber 56. Any suitable scrubber 56 may be incorporated and will be essentially the choice of the designer based on the requirements of the overall circuit. Typical manufactures of wet scrubbers include The Babcock and Wilcox Company， Marsulex， Kawaski Heavy Industries， Mitsui， Chiyoda， Thyssen KEA， inter alia. Numerals 58 and 60 denote further possible oxidant injection points where the aqueous solution of the oxidant is recirculated into the scrubber 56. A suitable pump 62 may be included with each circulation loop of the oxidant. These steps are optional， since it has been indicated herein previously that the oxidant can be introduced at any point from the flue gas duct to the wet scrubber and still function to achieve the goal of oxidizing any compounds present. The solution from scrubber 56， broadly denoted by numeral 64 may be removed from time to time for processing.
As a further optional step， a wet electrostatic precipitator may be introduced into the circuit， where the gas stream is passed through the electrostatic precipitator to polish the flue gas of any further particulate， fine particulates， water droplets or aerosols from the stream. This is an optional step and is not essential to the process. Once through the ESP， the flue gas can then be discharged through the stack. The wet ESP may or may not be an extension to the wet scrubber.
In terms of the overall reactions that occur in the process， the reactions that occur in the dry injection phase are simply those that involve the sodium bicarbonate contacting the SOx and NOx compounds which would be similar equations if potassium bicarbonate were uses. Exemplary of the actions of the SOx chemistry that occur in the injection apparatus include thefollowing：
Figure PCTCN2017097804-appb-000015
In addition to the SOx reactions there are additionally NOx reactions occurring in the injection phase which include the following：
Figure PCTCN2017097804-appb-000016
Figure PCTCN2017097804-appb-000017
In terms of the reactions that occur in the wet scrubber， many of the NOx reactions indicated above occur in the wet scrubbing phase as well as the following acid gas reactions：
Figure PCTCN2017097804-appb-000018
As discussed herein previously， the oxidant loops where oxidant is injected into the wet scrubber by points 58 and 60. Typical of the reactions that will occur from an oxidation point of view include the following：
Figure PCTCN2017097804-appb-000019
Figure PCTCN2017097804-appb-000020
S2O8-+NO+H2O＝2HSO4-+NO2
Figure PCTCN2017097804-appb-000021
2NO2+4Na2SO3＝＞N2+4Na2SO4
OH·+NO＝H++NO2
As a particular convenience， the dry injection operation as well as the wet scrubbing operation are particularly useful in reducing other air toxic compounds present in the flue gas.
In conclusion， by combining all kinds of the operations， the concentrations of SO2 and NOx were reduced immediately primarily due to their respective chemical reactions with NaHCO3. Other sorbents clearly will also provide effectiveness， namely sodium carbonate， sodium hydroxide， or any combination of these plus their potassium counterparts.
Reference to U.S. Patent Nos. 6,143,263 and 6,303,083 may be made for other examples in SOx removal.

Claims (64)

  1. A method of removing air pollutant from a flue gas stream, characterized in that the method comprises：
    (I) a process of catalytic combustion operation:
    catalytic combustion operation: adding a chemical additive as a combustion enhancer into a combustion equipment, in which a fuel such as a coal or bio-fuels is combusted wherein the chemical additive is a mixture of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn3O4) .
  2. The method of claim 1, wherein the method further comprises (K) a process of adsorption operation； preferably, the process is performed by an electrostatic precipitator.
  3. The method of claim 1 or 2, wherein the method further comprises (II) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation after (I) the process of catalytic combustion operation； preferably, before (K) the process of adsorption operation.
  4. The method of any one of claims 1-3, wherein the method further comprises (III) a process of scrubbing operations， wherein (III) the process of scrubbing operations is preferably after (II) the denitrification process.
  5. The method of any one of claims 1-4, wherein a fuel conditioning agent is added into the combustion equipment before, after or while adding the chemical additive in the process (I) of catalytic combustion operation.
  6. The method of claim 5, wherein the fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfite, sodium sulfate, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfite, potassium sulfate, potassium carbonate, potassium bicarbonate and potassium hydroxide.
  7. The method of any one of claims 3-6, wherein (II) the denitrification process is the process through selective non-catalytic reduction operation, and an ammonia injection is performed in the temperature range of 900-1050℃ or an urea injection is performed in the temperature range of 850-1150℃ during selective non catalytic reduction operation.
  8. The method of any one of claims 3-6, wherein (II) the denitrification process is the process through selective catalytic reduction operation, wherein vanadium, platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature； preferably, vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430℃ during the selective catalytic reduction operation.
  9. The method of any one of claims 4-8, wherein (III) the process of scrubbing operations  further comprises one or more steps selected from the following steps:
    (a) a dry injection scrubbing operation；
    (b) a wet scrubbing operation in the wet scrubber； and/or
    (c) and/or an oxidation scrubbing operation.
  10. The method of claim 9, wherein a flue gas stream containing mercury, arsenic, selenium, particulate matter, sulfur oxides, VOC’s, dioxins and/or nitrogen oxides compounds is contacted with a sorbent selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate, potassium hydroxide, calcium carbonate, calcium bicarbonate, calcium hydroxide, magnesium carbonate, magnesium bicarbonate and magnesium hydroxide, during (a) the step of a dry injection scrubbing operation； wherein the sorbent is preferably one or more selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate and sodium hydroxide.
  11. The method of claim 10, wherein said stream is further scrubbed in a scrubber during (b) the step of a wet scrubbing operation which is performed after (a) the step of said dry injection scrubbing operation.
  12. The method of any one of claims 9-11, wherein an oxidant is added to said stream during (c) the step of an oxidation scrubbing operation； and preferably, (c) the step of an oxidation scrubbing operation is performed after (b) the step of a wet scrubbing operation.
  13. The method of any one of claims 9-12, wherein a basic solution comprises one or more compound selected from sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate and potassium hydroxide； preferably a basic solution comprises one or more compound selected from sodium carbonate, sodium sulfate and sodium sulfite, more preferably a basic solution with pH 6.5-11, preferably 8.5-11 which predominately comprises a mixture of sodium carbonate, sodium sulfate and sodium sulfite, is added in the scrubber during (b) the step of a wet scrubbing operation.
  14. The method of claim 12 or 13, wherein the oxidant is one or more selected from the group consisting of hydrogen peroxide, potassium permanganate, hydroxyl radicals, sodium persulfate, ozone and NaClOx, where x is 1 through 4.
  15. The method of any one of claims 4-14, wherein the electrostatic precipitator during (K) the process of adsorption operation is located before a scrubber of (III) the process of scrubbing operations.
  16. The method of any one of claims 1-15, wherein said air pollutant include any one material selected from particulate matter, VOC, dioxins, heavy metal such as mercury, arsenic, selenium,  SOx and NOx compounds and any combination thereof.
  17. The method of any one of claims 9-15, wherein (III) the process of scrubbing operations further comprises in sequence the three following steps:
    (a) a dry injection scrubbing operation；
    (b) a wet scrubbing operation in the wet scrubber；
    and (c) and/or an oxidation scrubbing operation.
  18. The method of any one of claims 4-14, wherein (K) the process of adsorption operation is performed by an electrostatic precipitator after or before (III) the process of scrubbing operations.
  19. The method of any one of claims 2-18, wherein (K) the process of adsorption operation is performed by a bag house or a hot cyclone， or by a scrubber internal located in a scrubber； preferably by any combination of two or more devices selected from an electrostatic precipitator, a bag house, a hot cyclone， and a scrubber internal located in a scrubber； more preferably by combination of an electrostatic precipitator with any one or more devices selected from a bag house, a hot cyclone， and a scrubber internal located in a scrubber.
  20. The method of claim 19, wherein a scrubber internal is located in a scrubber for (b) the step of a wet scrubbing operation.
  21. A method of removing air pollutant from a flue gas stream, characterized in that the method comprises:
    (I) a process of adding a fuel conditioning agent is added into a combustion equipment during combustion operation, in which a fuel such as a coal or bio-fuels are charged before or after or while adding the fuel additive.
  22. The method of claim 21, wherein the method further comprises (K) a process of adsorption operation, preferably, the process of adsorption operation is performed by an electrostatic precipitator.
  23. The method of claim 21 or 22, wherein the method further comprises (II) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation after (I) the process of adding a fuel conditioning agent into a combustion equipment； preferably before (K) the process of adsorption operation.
  24. The method of any one of claims 21-23, wherein the method further comprises (III) a process of scrubbing operations, wherein (III) the process of scrubbing operations is preferably after (II) the denitrification process.
  25. The method of any one of claims 21-24, wherein the fuel conditioning agent is one or more compound selected from the group consisting of sodium sulfite, sodium sulfate, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfite, potassium sulfate, potassium carbonate, potassium bicarbonate and potassium hydroxide.
  26. The method of any one of claims 23-25, wherein (II) the denitrification process is the process through selective non catalytic reduction operation, and an ammonia injection is performed in the temperature range of 900-1050℃ or an urea injection is performed in the temperature range of 850-1150℃ during selective non catalytic reduction operation.
  27. The method of any one of claims 23-25, wherein (II) the denitrification process is carried out through selective catalytic reduction operation, wherein vanadium, platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature； preferably, vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430℃ during the selective catalytic reduction operation.
  28. The method of any one of claims 24-27, wherein (III) the process of scrubbing operations further comprises one or more steps selected from the following steps:
    (a) a dry injection scrubbing operation；
    (b) a wet scrubbing operation in the wet scrubber； and/or
    (c) and/or an oxidation scrubbing operation.
  29. The method of any one of claims 28, wherein a flue gas stream, containing mercury, arsenic, selenium, particulate matter, VOc’s, dioxins, sulfur oxides and/or nitrogen oxides compounds, is contacted with a sorbent selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate， potassium hydroxide, calcium carbonate, calcium bicarbonate, calcium hydroxide, magnesium carbonate, magnesium bicarbonate and magnesium hydroxide, during (a) the step of a dry injection scrubbing operation； wherein the sorbent is preferably selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide.
  30. The method of claim 29, wherein said stream is further scrubbed in a scrubber during (b) the step of a wet scrubbing operation which is performed after (a) the step of said dry injection scrubbing operation.
  31. The method of any one of claims 28-30, wherein an oxidant is added to said stream during (c) the step of an oxidation scrubbing operation； and preferably, (c) the step of an oxidation scrubbing operation is performed after (b) the step of a wet scrubbing operation.
  32. The method of any one of claims 28-31, wherein a basic solution comprises one or more compound selected from sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate and potassium hydroxide； preferably a basic solution comprises one or more compound selected from sodium carbonate, sodium sulfate, and sodium sulfite； more preferably a basic solution with pH 6.5-11, preferably 8.5-11 which predominately comprises a mixture of  sodium carbonate, sodium sulfate, and sodium sulfite, is added in the scrubber during (b) the step of a wet scrubbing operation.
  33. The method of claim 31 or claim 32 wherein the oxidant is selected from the group consisting of hydrogen peroxide, potassium permanganate, ozone sodium persulfate, hydroxyl radicals, NaClOx, where x is 1 through 4.
  34. The method of any one of claims 24-33, wherein the electrostatic precipitator during (K) the process of adsorption operation is located before a scrubber of (III) the process of scrubbing operations.
  35. The method of any one of claims 21-34, wherein said air pollutant include any one material selected from particulate matter, VOC’s, dioxins, heavy metal such as mercury, arsenic, selenium, SOx and NOx compounds and any combination thereof.
  36. The method of any one of claims 28-35, wherein (III) the process of scrubbing operations further comprises in sequence the three following steps:
    (a) a dry injection scrubbing operation；
    (b) a wet scrubbing operation in the wet scrubber；
    and (c) and/or an oxidation scrubbing operation.
  37. The method of any one of claims 24-33, wherein (K) the process of adsorption operation is performed by an electrostatic precipitator after or before (III) a process of scrubbing operations.
  38. The method of any one of claims 22-37, wherein (K) the process of adsorption operation is performed by a bag house or a hot cyclone, or by a scrubber internal located in a scrubber for a wet scrubbing operation； preferably by any combination of two or more devices selected from an electrostatic precipitator, a bag house, a hot cyclone, and a scrubber internal located in a scrubber for a wet scrubbing operation； more preferably by combination of an electrostatic precipitator with any one or more devices selected from an electrostatic precipitator, a bag house, a hot cyclone, and a scrubber internal located in a scrubber for a wet scrubbing operation.
  39. The method of claim 38, wherein a scrubber internal is located in a scrubber for (b) the step of a wet scrubbing operation.
  40. A method of removing air pollutant from a flue gas stream, characterized in that the method comprises:
    (1) a denitrification process through selective non-catalytic reduction or selective catalytic reduction operation and (K) a process of adsorption operation.
  41. The method of claim 40, wherein (K) the process of adsorption operation is performed by an electrostatic precipitator.
  42. The method of claim 41 or 42, wherein the method further comprises (2) a process of scrubbing operations after (1) the denitrification process.
  43. The method of any one of claims 40-42, wherein (1) the denitrification process is the process through selective non-catalytic reduction operation, and an ammonia injection is performed in the temperature range of 900-1050℃ or an urea injection is performed in the temperature range of 850-1150℃ during selective non catalytic reduction operation.
  44. The method of any one of claims 40-42, wherein (1) the denitrification process is the process through selective catalytic reduction operation, wherein vanadium, platinum or titanium as a catalyst is used at lower temperature and zeolite is used at higher temperature； preferably, vanadium-titanium catalyst system is used in the process and the optimum operating temperature for the catalyst is in the range of 280-430℃ during the selective catalytic reduction operation.
  45. The method of any one of claims 42-44, wherein (2) the process of scrubbing operations further comprises one or more steps selected from the following steps:
    (a) a dry injection scrubbing operation；
    (b) a wet scrubbing operation in the wet scrubber； and/or
    (c) and/or an oxidation scrubbing operation.
  46. The method of claim 45, wherein a flue gas stream containing mercury, arsenic, selenium, VOC’s, dioxins, particulate matter, sulfur oxides and nitrogen oxides compounds is contacted with a sorbent selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate， potassium hydroxide, calcium carbonate, calcium bicarbonate, calcium hydroxide, magnesium carbonate, magnesium bicarbonate and magnesium hydroxide, during (a) the step of a dry injection scrubbing operation； wherein the sorbent is preferably selected from the group consisting of sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide.
  47. The method of claims 46, wherein said stream is scrubbed in a scrubber during (b) the step of a wet scrubbing operation which is performed after (a) the step of said dry injection scrubbing operation.
  48. The method of any one of claims 45-47, wherein an oxidant is added to said stream during (c) the step of an oxidation scrubbing operation； and preferably, (c) the step of an oxidation scrubbing operation is performed after (b) the step of a wet scrubbing operation.
  49. The method of any one of claims 45-48, wherein a basic solution comprises one or more compound selected from sodium sulfate, sodium sulfite, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium sulfate, potassium sulfite, potassium carbonate, potassium bicarbonate and potassium hydroxide； preferably a basic solution comprises one or more compound selected from sodium carbonate, sodium sulfate, and sodium sulfite； more preferably a basic solution with pH 6.5-11, preferably 8.5-11 which predominately comprises a mixture of  sodium carbonate, sodium sulfate and sodium sulfite, is added in the scrubber during (b) the step of a wet scrubbing operation.
  50. The method of claim 48 or 49, wherein the oxidant is selected from the group consisting of hydrogen peroxide, potassium permanganate, ozone, sodium persulfate, hydroxyl radicals, NaClOx, where x is 1 through 4.
  51. The method of any one of claims 42-50, wherein the electrostatic precipitator during (K) the process of adsorption operation is located before a scrubber of (2) the process of scrubbing operations.
  52. The method of any one of claims 40-51, wherein said air pollutant include any one material selected from particulate matter, VOC, dioxins, heavy metal such as mercury, arsenic, selenium, SOx and NOx compounds and any combination thereof.
  53. The method of any one of claims 42-52, wherein (2) the process of scrubbing operations further comprises in sequence the three following steps:
    (a) a dry injection scrubbing operation；
    (b) a wet scrubbing operation (particulate matter removal enhancements) in the wet scrubber；
    and (c) and/or an oxidation scrubbing operation.
  54. The method of any one of claims 41-53, wherein (K) the process of adsorption operation is performed by an electrostatic precipitator after or before (2) a process of scrubbing operations.
  55. The method of any one of claims 41-54, wherein (K) the process of adsorption operation is performed by a bag house or a hot cyclone, or by a scrubber internal located in a scrubber for a wet scrubbing operation； preferably by any combination of two or more devices selected from an electrostatic precipitator, a bag house a hot cyclone, and a scrubber internal located in a scrubber for a wet scrubbing operation； more preferably by combination of an electrostatic precipitator with any one or more devices selected from an electrostatic precipitator, a bag house, a hot cyclone, and a scrubber internal located in a scrubber for a wet scrubbing operation.
  56. The method of claim 55, wherein a scrubber internal is located in a scrubber for (b) the step of a wet scrubbing operation.
  57. The method of any one of claims 1-56, wherein the fuel conditioning agent is added into the fuel before feeding to the boiler.
  58. The method of any one of claims 1-57, wherein the fuel conditioning agent is added into the fuel in 0.08-1 weight ％, preferably 0.09-0.8 weight ％ of a weight ratio of the fuel conditioning agent to the fuel, preferably, the sodium sulfate as fuel conditioning agent is added into the coal in 0.09-0.6 weight ％ of a weight ratio of the fuel conditioning agent to the coal； more preferably, the sodium sulfate as fuel conditioning agent is added into the coal in 0.1-0.3 weight ％ of a weight ratio  of the fuel conditioning agent to the coal.
  59. The method of any one of claims 1-58, wherein the chemical additive is added into the combustion equipment in 0.01-0.05 weight ％ of a weight ratio of the chemical additive to the fuel； preferably, the chemical additive is the mixture of manganese, iron, silicon and calcium loaded in a carrier of Manganese (II, III) oxide, preferably tri-manganese tetroxide (Mn3O4) ； more preferably, the chemical additive includes Mn3O4 17-51％ by weight Mn, Fe 5-16 wt. ％, CaO 3-35 wt. ％ and SiO2 2-11％； further more preferably, the chemical additive includes Mn3O4 20-48％ by weight Mn, Fe 8-14 wt. ％, CaO 10-35 wt. ％ and SiO2 5-10％； further more preferably, the chemical additive includes Mn3O4 40-51％ by weight Mn, Fe 11-16 wt. ％, CaO 17-33 wt. ％ and SiO2 5-11％.
  60. The method of any of the claims 1-59, wherein the amount of chemical absorbent injected into the flue gas during the step of dry injection operation is injected into the flue gas in the range of 0.8 to 1.5 the stoichiometric requirements to remove all of the SOx and NOx compounds in the flue gas.
  61. A method of conditioning the PM collection efficiency of an electrostatic precipitator, wherein a fuel conditioning agent is added into the fuel before or during combustion of a fuel.
  62. The method of claim 61, wherein the fuel conditioning agent is added into the fuel is 0.08-1 weight ％ of the fuel conditioning agent to the fuel, preferably, the sodium sulfate as fuel conditioning agent is added into the coal in 0.09-0.6 weight ％ of the fuel conditioning agent to the coal； more preferably, the sodium sulfate as fuel conditioning agent is added into the coal in 0.1-0.3 weight ％ of a weight ratio of the fuel conditioning agent to the coal.
  63. The method of claim 61 or 62, wherein the PM collection efficiency of an electrostatic precipitator is enhanced in the range of 0.5-1.9％.
  64. The method of any one of claims 1-63, wherein an addition amount of the oxidants during (c) the step of oxidation scrubbing operation is in the range of 0.8 to 1.5 stoichiometric requirements to remove all of the SO2 and NO compounds in the flue gas.
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CN109569240A (en) * 2018-12-14 2019-04-05 山东汇之蓝环保科技有限公司 NO_x Reduction by Effective ionic liquid and its application method
CN109908721A (en) * 2018-12-21 2019-06-21 四川大学 A kind of method that sodium salt method removes heavy metal arsenic in low-temperature flue gas
CN110585868A (en) * 2019-10-12 2019-12-20 沈洪彬 Preparation and application of dry-wet dual-purpose flue gas desulfurization and denitrification agent
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CN111715057A (en) * 2020-07-14 2020-09-29 陕西煤业化工技术研究院有限责任公司 Method and process system for realizing multi-component recovery and resource utilization of flue gas
CN112295601A (en) * 2019-08-02 2021-02-02 中国石油化工股份有限公司 Oxidation catalyst for treating styrene waste gas and preparation method and application thereof
US10940471B1 (en) 2019-10-30 2021-03-09 W. L. Gore & Associates, Inc. Catalytic efficiency of flue gas filtration
CN112742204A (en) * 2020-12-30 2021-05-04 铜陵铜冠神虹化工有限责任公司 Flue gas sulfur-fixing agent used in sodium sulfide synthesis process and preparation process thereof
CN112791561A (en) * 2021-01-13 2021-05-14 贵州威顿晶磷电子材料股份有限公司 Trimethyl phosphite rectification tail gas deodorization method and equipment
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CN113441000A (en) * 2020-03-27 2021-09-28 上海梅山钢铁股份有限公司 Low-cost sintering flue gas denitration device and method
CN113559818A (en) * 2021-07-28 2021-10-29 华南理工大学 Calcium-iron type heavy metal adsorbent and preparation and application thereof

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CN109569240A (en) * 2018-12-14 2019-04-05 山东汇之蓝环保科技有限公司 NO_x Reduction by Effective ionic liquid and its application method
CN109569240B (en) * 2018-12-14 2021-08-13 山东汇之蓝环保科技有限公司 Efficient denitration ionic liquid and use method thereof
CN109908721A (en) * 2018-12-21 2019-06-21 四川大学 A kind of method that sodium salt method removes heavy metal arsenic in low-temperature flue gas
CN112295601B (en) * 2019-08-02 2023-03-31 中国石油化工股份有限公司 Oxidation catalyst for styrene waste gas treatment and preparation method and application thereof
CN112295601A (en) * 2019-08-02 2021-02-02 中国石油化工股份有限公司 Oxidation catalyst for treating styrene waste gas and preparation method and application thereof
CN110585868A (en) * 2019-10-12 2019-12-20 沈洪彬 Preparation and application of dry-wet dual-purpose flue gas desulfurization and denitrification agent
CN110791669A (en) * 2019-10-15 2020-02-14 宁夏科通新材料科技有限公司 Low-aluminum-silicon-calcium alloy production device and process
US10940471B1 (en) 2019-10-30 2021-03-09 W. L. Gore & Associates, Inc. Catalytic efficiency of flue gas filtration
US11071947B2 (en) 2019-10-30 2021-07-27 W. L. Gore & Associates, Inc. Catalytic efficiency of flue gas filtration
US11602717B2 (en) 2019-10-30 2023-03-14 W. L. Gore & Associates, Inc. Catalytic efficiency of flue gas filtration
CN113441000A (en) * 2020-03-27 2021-09-28 上海梅山钢铁股份有限公司 Low-cost sintering flue gas denitration device and method
CN113441000B (en) * 2020-03-27 2023-07-18 上海梅山钢铁股份有限公司 Low-cost sintering flue gas denitration device and method
CN111715057A (en) * 2020-07-14 2020-09-29 陕西煤业化工技术研究院有限责任公司 Method and process system for realizing multi-component recovery and resource utilization of flue gas
CN112742204A (en) * 2020-12-30 2021-05-04 铜陵铜冠神虹化工有限责任公司 Flue gas sulfur-fixing agent used in sodium sulfide synthesis process and preparation process thereof
CN112742204B (en) * 2020-12-30 2022-07-19 铜陵铜冠环保科技有限公司 Flue gas sulfur-fixing agent used in sodium sulfide synthesis process and preparation process thereof
CN112791561A (en) * 2021-01-13 2021-05-14 贵州威顿晶磷电子材料股份有限公司 Trimethyl phosphite rectification tail gas deodorization method and equipment
CN112791561B (en) * 2021-01-13 2022-07-19 贵州威顿晶磷电子材料股份有限公司 Trimethyl phosphite rectification tail gas deodorization method and equipment
CN113559818A (en) * 2021-07-28 2021-10-29 华南理工大学 Calcium-iron type heavy metal adsorbent and preparation and application thereof

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