Classifications

• • 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
  • B01D53/86—Catalytic processes
  • B01D53/8621—Removing nitrogen compounds
  • B01D53/8625—Nitrogen oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/55—Compounds of silicon, phosphorus, germanium or arsenic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/60—Heavy metals or heavy metal compounds
  • B01D2257/602—Mercury or mercury compounds

Definitions

• the present invention relates generally to the field of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) and, in particular to a new and useful method and apparatus for reducing or preventing the poisoning and/or contamination of an SCR catalyst.
• the method and apparatus of the present invention is designed to protect the SCR catalyst.
• the present invention relates to a method and apparatus for increasing the service life and/or catalytic activity of an SCR catalyst while simultaneously controlling various emissions.
• the present invention relates to a method and apparatus for controlling, mitigating and/or reducing the amount of selenium contained in and/or emitted by one or more pieces of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.).
• the present invention relates to method and apparatus for controlling the selenium speciation in one, or both, of a gas phase or an aqueous phase by the addition of at least one metal additive upstream of either a wet flue gas desulfurization (WFGD) unit and/or a dry flue gas desulfurization (DFGD) unit.
• WFGD wet flue gas desulfurization
• DFGD dry flue gas desulfurization
• ⁇ refers to the cumulative emissions of nitric oxide (NO), nitrogen dioxide (NO2) and trace quantities of other nitrogen oxide species generated during combustion. Combustion of any fossil fuel generates some level of NO x due to high temperatures and the availability of oxygen and nitrogen from both the air and fuel. ⁇ emissions may be controlled using low NO x combustion technology and post- combustion techniques.
• One such post-combustion technique involves selective catalytic reduction (SCR) systems in which a catalyst facilitates a chemical reaction between NO x and a reagent (usually ammonia) to produce molecular nitrogen and water vapor.
• SCR selective catalytic reduction
• SCR technology is used worldwide to control NO x emissions from combustion sources. This technology has been used widely in Japan for NO x control from utility boilers since the late 1970's, in Germany since the late 1980's, and in the US since the 1990's.
• Industrial scale SCRs have been designed to operate principally in the temperature range of 500°F to 900°F, but most often in the range of 550°F to 750°F.
• SCRs are typically designed to meet a specified NO x reduction efficiency at a maximum allowable ammonia slip. Ammonia slip is the concentration, expressed in parts per million by volume, of unreacted ammonia exiting the SCR.
• ammonia reacts with NO x according to one or more of the following stoichiometric reactions (a) to (d):
• Suitable catalysts are discussed in, for example, United States Patent Nos. 5,540,897; 5,567,394; and 5,585,081 to Chu et al., all of which are hereby incorporated by reference as though fully set forth herein. Catalyst formulations generally fall into one of three categories: base metal, zeolite and precious metal.
• Base metal catalysts use titanium oxide with small amounts of vanadium, molybdenum, tungsten or a combination of several other active chemical agents.
• the base metal catalysts are selective and operate in the specified temperature range.
• the major drawback of the base metal catalyst is its potential to oxidize SO 2 to SO 3 ; the degree of oxidation varies based on catalyst chemical formulation.
• the quantities of SO 3 which are formed can react with the ammonia carryover to form various ammonium-sulfate salts.
• Zeolite catalysts are aluminosilicate materials which function similarly to base metal catalysts.
• One potential advantage of zeolite catalysts is their higher operating temperature of about 970°F (521 °C). These catalysts can also oxidize SO 2 to SO 3 and must be carefully matched to the flue gas conditions.
• Precious metal catalysts are generally manufactured from platinum and rhodium. Precious metal catalysts also require careful consideration of flue gas constituents and operating temperatures. While effective in reducing NO x , these catalysts can also act as oxidizing catalysts, converting CO to CO 2 under proper temperature conditions. However, SO 2 oxidation to SO 3 and high material costs often make precious metal catalysts less attractive.
• SCR catalysts undergo poisoning when they become contaminated by various compounds including, but not limited to, certain phosphorus compounds such as phosphorus oxide (PO) or phosphorus pentoxide (P 2 O 5 ). Additionally, it is also well known that SCR catalysts degrade over time and have to be replaced periodically at a significant cost and loss of generating capacity. In a typical 100 MWe coal plant the downtime and cost associated with the replacement of underperforming catalyst can be in the neighborhood of one million US dollars or more.
• PO phosphorus oxide
• P 2 O 5 phosphorus pentoxide
• Powder River Basin/Lignite coal plants, any coal/biomass co-combustion, or any coal/bone meal co-combustion or even pure biomass combustion power plants will suffer from phosphorus contamination of their SCR catalysts.
• other types of fossil fuel-fired combustion processes can generate phosphorus levels that lead to undesirable levels of phosphorus contamination of an SCR catalyst.
• fuel oil combustion processes can, in some instances, suffer from phosphorus levels that lead to undesirable levels of phosphorus contamination of an SCR catalyst.
• the term "fuel oil” means any type of liquid fossil fuel (e.g., liquid petroleum), regardless of type, number or grade, that can be combusted to produce heat.
• emission controls beyond controlling NO x emissions, other emission controls must be considered and/or met in order to comply with various state, EPA and/or Clean Air Act regulations.
• Some other emission controls which need to be considered for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices include, but are not limited to, mercury, SO x , and certain particulates.
• WFGD wet flue gas desulfurization
• DFGD dry flue gas desulfurization
• One suitable method of mercury control is mercury oxidation and capture via the use of one or more halogen compounds to accomplish the aforesaid mercury oxidation and the subsequently capturing the oxidized mercury compound (e.g., in the form of a mercuric halide).
• halogen compounds e.g., halide salts such as calcium bromide, etc.
• halide salts such as calcium bromide, etc.
• the present invention is not limited to just the aforementioned situation.
• the present invention relates to a method and apparatus for controlling, mitigating and/or reducing the amount of selenium contained in and/or emitted by one or more pieces of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.).
• the present invention relates to method and apparatus for controlling the selenium speciation in one, or both, of a gas phase or a aqueous phase by the addition of at least one metal additive at any point upstream (as will be detailed below) of either a wet flue gas desulfurization (WFGD) unit and/or a dry flue gas desulfurization (DFGD) unit.
• WFGD wet flue gas desulfurization
• DFGD dry flue gas desulfurization
• present invention offers a method and apparatus by which to simultaneously control at least selenium speciation in one, or both, of a gas phase or an aqueous phase while further controlling at least one of gas phase phosphorus, gas phase sodium, gas phase potassium, and/or mercury in at least one emission from a combustion process.
• gas phase compounds such as phosphorus, sodium, and/or potassium
• the present invention relates generally to the field of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) and, in particular to a new and useful method and apparatus for reducing or preventing the poisoning and/or contamination of an SCR catalyst.
• the method and apparatus of the present invention is designed to protect the SCR catalyst.
• the present invention relates to a method and apparatus for increasing the service life and/or catalytic activity of an SCR catalyst while simultaneously controlling various emissions.
• the present invention relates to a method and apparatus for controlling, mitigating and/or reducing the amount of selenium contained in and/or emitted by one or more pieces of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.).
• the present invention relates to method and apparatus for controlling the selenium speciation in one, or both, of a gas phase or an aqueous phase by the addition of at least one metal additive upstream of either a wet flue gas desulfurization (WFGD) unit and/or a dry flue gas desulfurization (DFGD) unit.
• WFGD wet flue gas desulfurization
• DFGD dry flue gas desulfurization
• one aspect of the present invention is drawn to a method for increasing the active life of an SCR catalyst, the method comprising the steps of: (a) providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; (b) permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus-containing compounds, present in the combustion zone or flue gas prior to the entry of the flue gas into the SCR; (c) providing at least one halide-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR, with the proviso that halide-bearing compound is not an iron halide; and (d) permitting the at least one halide-bearing compound to react with and/or oxidize any mercury present in the combustion zone or flue gas, wherein the method achieves an increase in either
• a method for increasing the active life of an SCR catalyst comprising the steps of: (i) providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; (ii) permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus-containing compounds, present in the combustion zone or flue gas prior to the entry of the flue gas into the SCR; (iii) providing at least one halide-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR, with the proviso that halide-bearing compound is not an iron halide; and (iv) permitting the at least one halide-bearing compound to react with and/or oxidize any mercury present in the combustion zone or flue gas, wherein the method achieves
• a method for simultaneously sequestering one or more phosphorus compounds, or phosphorus-containing compounds, in the form of one or more less reactive iron- phosphorus-containing compounds, and oxidizing mercury comprising the steps of: (A) providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler; (B) permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus- containing compounds, present in the combustion zone or flue gas to form one or more less reactive iron-phosphorus-containing compounds; (C) providing at least one halide-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR, with the proviso that halide- bearing compound is not an iron halide; and (D) permitting the at least one halide- bearing compound to react with and/or oxidize any mercury
• a method for simultaneously sequestering one or more phosphorus compounds, or phosphorus-containing compounds, in the form of one or more less reactive iron- phosphorus-containing compounds, and oxidizing mercury comprising the steps of: (I) providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler; (II) permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus- containing compounds, present in the combustion zone or flue gas to form one or more less reactive iron-phosphorus-containing compounds; (III) providing at least one halide-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR, with the proviso that halide- bearing compound is not an iron halide; and (IV) permitting the at least one halide- bearing compound to react with and/or oxidize any
• a method for sequestering one or more phosphorus compounds, or phosphorus- containing compounds, in the form of one or more less reactive iron-phosphorus- containing compounds while concurrently sequestering mercury comprising the steps of: providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler; permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus-containing compounds, present in the combustion zone or flue gas to form one or more less reactive iron-phosphorus-containing compounds; providing at least one halide-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR, with the proviso that halide-bearing compound is not an iron halide; and permitting the at least one halide- bearing compound to react with and/or oxidize any mercury present in the combustion zone or flue gas
• a method for controlling the selenium speciation in a flue gas and/or in at least one piece of emission control equipment comprising the steps of: providing at least one metal-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; and permitting the at least one metal-bearing compound to react with any selenium and/or selenium compounds present in the combustion zone, flue gas, gas phase and/or at least one piece of emission control equipment, wherein the method permits the control of the selenium speciation in one or more of the gas phase and/or in the at least one piece of emission control equipment thereby resulting in a reduction in the amount of selenium emitted in a flue gas and/or from one or more pieces of emission control equipment.
• a method for simultaneously increasing the active life of an SCR catalyst and controlling the selenium speciation in a flue gas and/or selenium speciation in at least one piece of emission control equipment comprising the steps of: providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; and simultaneously permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus-containing compounds, present in the combustion zone or flue gas as well as any selenium and/or selenium compounds present in the combustion zone, flue gas, gas phase and/or at least one piece of emission control equipment prior to the entry of the flue gas into the SCR, wherein the method achieves an increase in either one, or both, of a catalytic activity and/or a catalytic lifespan of at least about 10 percent at an operational time of at least about 2,000 hours while simultaneously permitting
• a method for controlling the selenium speciation in a flue gas and/or in at least one piece of emission control equipment in conjunction with a post combustion CO 2 capture process comprising the steps of: providing at least one metal- bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; and permitting the at least one metal- bearing compound to react with any selenium and/or selenium compounds present in the combustion zone, flue gas, gas phase and/or at least one piece of emission control equipment, wherein the method permits the control of the selenium speciation in one or more of the gas phase and/or in the at least one piece of emission control equipment thereby resulting in a reduction in the amount of selenium emitted in a flue gas, from one or more pieces of emission control equipment and/or in at least one amine compound that is utilized in conjunction with the post combustion CO 2 capture process.
• Figure 1 is a schematic representation of a typical fossil fuel burning facility with an SCR system, and which includes a system for practicing the methods of the present invention.
• Figure 2 is a graph illustrating one example of an increase in catalytic activity and/or catalytic lifespan as realized via utilization of a system and method in accordance with one embodiment of the present invention.
• an ammoniacal compound is a term meant to include compounds such as urea, ammonium sulfate, cyanuric acid, and organic amines as well as ammonia (NH 3 ). These compounds could be used as reducing agents in addition to ammonia, but as mentioned above, ammonia is frequently preferred for economic reasons. Some non-ammoniacal compounds such as carbon monoxide or methane can be used as well, but with loss in effectiveness.
• the present invention is described in terms of a mercury oxidation and capture method that utilizes a halogen compound that is in the form a halide salt ⁇ e.g., calcium bromide), the present invention is not limited to just this type of mercury oxidation and capture. Rather, any type of mercury control method can be utilized in conjunction with the present invention as the present invention, in various embodiments, seeks to control simultaneously the amount of gas phase phosphorus and the nature of the selenium speciation. In other embodiments, the present invention seeks to control simultaneously the amount of gas phase phosphorus, the amount of mercury and the nature of the selenium speciation in a flue gas.
• the present invention is described in relation to a boiler, or a fossil fuel boiler, it is not limited solely thereto. Instead, the present invention can be applied to any combustion source that generates NO x regardless of whether such a combustion source is utilized in conjunction with a boiler, or a steam generator.
• the present invention could be used in combination with a kiln, a heater, or any other type of combustion process that generates, in whole or in part, a flue gas or combustion gas containing NO x . Accordingly, the description below is to be construed as merely exemplary.
• the present invention may be applied to a boiler installation which employs a wet flue gas desulfurization (WFGD or wet scrubber) for removal of sulfur oxides from the flue gases, as shown in the upper right-hand side of Figure 1 .
• WFGD wet flue gas desulfurization
• the wet scrubber is typically preceded (with respect to a direction of flue gas flow through the system) by a particulate collection device (PCD), advantageously a fabric filter (FF) bag house, or an electrostatic precipitator (ESP).
• PCD particulate collection device
• FF fabric filter
• ESP electrostatic precipitator
• wet ESP wet electrostatic precipitator
• WESP wet electrostatic precipitator
• the present invention may be applied to a system which employs a spray dryer apparatus (SDA) or dry scrubber for removal of sulfur oxides from the flue gases, as shown in the lower right-hand side of Figure 1 .
• SDA spray dryer apparatus
• dry scrubber is typically followed (with respect to a direction of flue gas flow through the system) by a particulate collection device (PCD), advantageously a fabric filter (FF) or baghouse, an electrostatic precipitator (ESP) or even a wet electrostatic precipitator (wet ESP).
• PCD particulate collection device
• FF fabric filter
• ESP electrostatic precipitator
• wet ESP wet electrostatic precipitator
• the present invention can be applied to any SCR catalyst that is adversely affected by poisoning with a phosphorus-based compound such as, but not limited to, H 3 PO 4 , PO or P2O5.
• a phosphorus-based compound such as, but not limited to, H 3 PO 4 , PO or P2O5.
• the present invention is not limited to any one type of SCR catalyst, but rather is broadly applicable to a wide range of SCR catalyst systems. Suitable catalyst systems for which the present invention is applicable include, but are not limited to, honeycomb, plate or corrugated type configurations.
• the present invention is directed to reducing the rate of SCR catalyst deactivation on Powder River Basin (PRB) coal combustion units.
• PRB Powder River Basin
• the present invention is directed to reducing the rate of SCR catalyst deactivation on any type of fossil fuel-fired combustion unit where the fuel and/or combustion process utilized results in the generation of undesirable levels of gas phase phosphorus compounds that in turn result in the accumulation of such compounds in an SCR catalyst thereby leading to the an undesirable increase in the deactivation rate of such an SCR catalyst.
• the present invention is described in relation to PRB coal, the present invention is not limited thereto. Rather, the present invention is broadly applicable to any situation where an SCR catalyst is poisoned by one or more gaseous phosphorus compounds.
• phosphorus in PRB coal is suspected to cause rapid deactivation in staged combustion and other units.
• the phosphorus in any type of fossil fuel can lead to rapid deactivation in a fossil fuel- fired combustion unit. While not wishing to be bound to any one theory, it is believed that the deactivation is suspected to be caused by the gas phase phosphorus released via carbothermic reduction reaction. In this reaction under oxygen deficient conditions, phosphorus bearing compounds release gas phase phosphorus by the following reaction:
• the present invention relates to a system and method to prevent formation of gas phase phosphorus species in the combustion environment thus reducing, mitigating and/or eliminating the rate of SCR deactivation.
• the present invention accomplishes the aforementioned goal by the addition of at least one iron-bearing compound to the PRB coal prior to combustion.
• the at least one iron-bearing compound of the present invention can be added to any type of phosphorus-containing fossil fuel (e.g., mixed with, or supplied individually from, any type of fuel oil), or supplied to any of the injection points discussed below with regard to the various coal embodiments.
• the present invention is directed to a system and method designed to increase the catalytic activity and/or catalytic life span.
• the increase in catalytic activity and/or increase in catalytic life span is measured against a standard, or known, rate of decline in catalytic activity and/or life for a given a boiler, fossil fuel boiler, kiln, heater, or any other type of device that generates a flue gas or combustion gas containing NO x .
• the iron-bearing compounds of the present invention is any iron compound ⁇ e.g., an iron oxide compound) that is able to undergo reduction in the combustion environments common to boilers, furnaces, power plants, etc.
• the iron-bearing compound of the present invention can be a water soluble, or water insoluble, iron-bearing compound.
• Suitable water soluble iron-bearing inorganic compounds include, but are not limited to, iron (II) acetate (e.g., Fe(C 2 H 3 O 2 ) 2 » 4H 2 O), iron (II) nitrate (e.g., Fe(NO 3 ) 2 » 6H 2 O), iron (III) nitrate (e.g., Fe(NO 3 ) 3 » 6H 2 O or Fe(NO 3 ) 3 » 9H 2 O), iron (II) sulfate (e.g., FeSO 4 » H 2 O, FeSO 4 » 4H 2 O, FeSO 4 » 5H 2 O, or FeSO 4 » 7H 2 O), iron (III) sulfate (e.g., Fe 2 (SO ) 3 » 9H 2 O), or mixtures of two or more thereof.
• iron (II) acetate e.g., Fe(C 2 H 3 O 2 ) 2 » 4H 2 O
• iron (II) nitrate
• Suitable water insoluble iron-bearing compounds include but are not limited to, metallic iron, one or more iron oxides, iron carbonate, or mixtures of two or more thereof. Additionally, a wide range of water soluble, or water insoluble, organic iron bearing compounds could be utilized in conjunction with the present invention.
• the iron-bearing compound of the present invention can be supplied in any desirable form including, but not limited to, powderized form, solid form, as an aqueous solution, as an aqueous suspension or emulsion, or any combination of two or more different forms of iron-bearing compounds.
• the iron-bearing compound supplied via each different form can be the same or different.
• the iron-bearing compound is iron (III) oxide (Fe 2 O 3 ), also known as red iron oxide or hematite.
• iron (III) oxide Fe 2 O 3
• red iron oxide or hematite also known as red iron oxide or hematite.
• Fe 3 O 4 also known as black iron oxide or magnetite
• FeO » Fe 2 O 3 The FeO or iron (II) oxide, also known as ferrous oxide, which is generated due to the reduction of Fe 2 O 3 is then available to tie-up, bind and/or sequester any PO gas present in the combustion zone, or the flue gas, of a boiler, or furnace, prior to arrival at the SCR. This PO gas will then form Fe-P compounds in particulate phase prior to arrival at the SCR. The particulate will pass through the catalyst and avoid the catalyst deterioration.
• the present invention can utilize iron (II) carbonate which is converted to the desired iron (II) oxide in the combustion zone via the reaction shown below:
• the present invention can utilize a combination of one or more iron-containing compounds and one or more halide compounds, with the proviso that the halide containing compound is not an iron halide.
• at least one iron-containing compound is utilized in conjunction with at least one non-iron halide containing compound.
• the at least one iron compound has a generic formula of AX, where A is equal to iron and X is either an oxide or carbonate ion, anion, group, and/or moiety and the at least one halide compound has a generic formula of BY where B is any atom, element, or cation except for iron and Y is a halide selected from chlorine, bromine, fluorine, or iodine.
• suitable halides for use in conjunction with the present invention include, but are not limited to, potassium bromide, potassium chloride, potassium fluoride, potassium iodide, sodium bromide, sodium chloride, sodium fluoride, sodium iodide, calcium bromide, calcium chloride, calcium fluoride, calcium iodide, aluminum bromide, aluminum chloride, aluminum fluoride, aluminum iodide, other metal halides ⁇ e.g., bromides, chlorides, fluorides and/or iodides) with the proviso that the metal is not iron, or any mixture of two or more thereof.
• any one or more halide compounds in accordance with the proviso defined above can be used in combination with one or more non-halide containing iron compounds ⁇ e.g., iron (II) carbonate).
• the present invention utilizes a combination of iron (II) carbonate with calcium bromide to control the amount of phosphorus in a flue gas, or combustion gas while concurrently permitting both the control of mercury compounds, or mercury- containing compounds, in a flue gas, or combustion gas and the increase in catalytic activity and/or service life.
• the present invention utilizes a combination of iron (II) carbonate with calcium chloride to control the amount of phosphorus in a flue gas, or combustion gas while concurrently permitting both the control of mercury compounds, or mercury-containing compounds, in a flue gas, or combustion gas and the increase in catalytic activity and/or service life.
• the present invention utilizes a combination of iron (II) carbonate with either one, or both, of aluminum bromide and/or aluminum chloride to control the amount of phosphorus in a flue gas, or combustion gas while concurrently permitting both the control of mercury compounds, or mercury-containing compounds, in a flue gas, or combustion gas and the increase in catalytic activity and/or service life.
• mercury compounds, or mercury-containing compounds include, but are not limited to, any compound that contains either oxidized mercury, or bound elemental mercury.
• the present invention is directed to concurrently permitting the control of mercury compounds, or mercury-containing compounds, that contain primarily, or only, oxidized mercury.
• any iron compound suitable for use in conjunction with the present invention can be utilized in a hydrated or non-hydrated form.
• reference to any iron compound herein by definition includes any hydrated forms that exists whether or not specifically mentioned by chemical formula.
• halide-containing compounds are utilized to oxidize elemental mercury present in a flue, or combustion, gas.
• the halide portion of a suitable halide-containing compound permits elemental mercury to be converted into a more favorable form for subsequent capture, or sequestration, via one or more suitable environmental control technologies (e.g., a wet scrubber or spray dry absorber (SDA), a flue gas desulfurization system (FGD), a powdered activated carbon system (PAC), or a particulate collecting system such as a fabric filter (FF) or a electrostatic precipitator (ESP)).
• SDA wet scrubber or spray dry absorber
• FGD flue gas desulfurization system
• PAC powdered activated carbon system
• a particulate collecting system such as a fabric filter (FF) or a electrostatic precipitator (ESP)
• the addition of one or more suitable halide-containing compounds also increases the amount of mercury that is particulate-bound.
• the suitable one or more iron- bearing compounds, and if so desired the one or more halide compounds can be added to the coal via one or more pulverizers.
• the one or more iron-bearing compounds, and if so desired the one or more halide compounds, of the present invention can be added to the combustion zone of a boiler and/or furnace via one or more suitable supply lines designed to deliver a powderized, solid, aqueous suspension, suspension, or aqueous solution of the one or more iron-bearing compounds and/or the one or more halide compounds to the combustion zone of a furnace and/or boiler.
• Figure 1 illustrates several embodiments of suitable design schemes for accomplishing this result.
• FIG. 1 there is illustrated a schematic representation of a typical fossil fuel burning facility, generally designated 10, with an SCR system, and which includes a system for practicing the methods of the present invention.
• boiler 12 is provided for extracting the heat from the combustion of a fossil fuel, such as coal, through combustion with an oxidant, typically air.
• the heat is transferred to a working fluid, such as water, to generate steam used to either generate power via expansion through a turbine generator apparatus (not shown) or for industrial processes and/or heating.
• a working fluid such as water
• the raw coal 14 must be crushed to a desired fineness and dried to facilitate combustion.
• Raw coal 14 is temporarily stored in a coal bunker 16 and then transferred by means of a gravimetric or volumetric feeder 18 to one or more coal pulverizers 20.
• coal pulverizers A - F there are six (6) coal pulverizers, identified as coal pulverizers A - F.
• each coal pulverizer 20 grinds the coal to a desired fineness ⁇ e.g., 70 percent through 200 mesh) and as it is ground, hot primary air from primary air fans (not shown) is conveyed into each coal pulverizer 20 to preheat and remove moisture from the coal to desired levels as it is ground.
• the primary air is also used to convey the pulverized coal (PC) out of each coal pulverizer 20 and delivers it along a plurality of pulverized coal supply lines (one such burner line is identified at A in Figure 1 ; a single coal pulverizer 20 may supply coal through 4 to 8 pulverized coal supply lines) to the burners 22 on the front and rear walls of the boiler 12.
• the burners 22 are located in spaced elevations on one or both of the opposed front and rear walls of the boiler 12, or at the corners of the boiler in installations known as corner-fired or tangentially-fired units (not shown).
• the present invention can be utilized in conjunction with, but is not limited solely to, single-wall fired, opposed-wall fired and corner- or tangentially-fired units.
• a single coal pulverizer 20 typically only provides coal to a single elevation of burners 22 on a wall.
• the six coal pulverizers A - F supply corresponding burner elevations A - F.
• other pulverizer and burner configurations are known ⁇ e.g., single pulverizers supplying burners on multiple walls and/or elevations or multiple pulverizers supplying burners on a single elevation) and the present invention applies to any such configurations.
• the combustion process begins in the burner zone 24 of the boiler 12's furnace 26, releasing heat and creating hot flue gas 28 which is conveyed upwardly to the upper portion 30 of the boiler 12, across heating surfaces schematically indicated as rectangles 32.
• the flue gas 28 is then conveyed across the heating surfaces in the pendant convection pass 34, into the upper portion 36 of the horizontal convection pass 38.
• the flue gas 28 is then conveyed through a selective catalytic reduction (SCR) apparatus 40 where NO x in the flue gas is reduced, and then through primary and secondary air heater devices schematically indicated at 42.
• the air heaters 42 extract additional heat from the flue gas 28, lowering the temperature of the flue gas, and preheat the incoming air used for combustion.
• SCR selective catalytic reduction
• the first equipment configuration in Figure 1 comprises a particulate collection device (PCD) schematically indicated at 44, for removal of particulates from the flue gas 28, and which may comprise in practice a fabric filter or an electrostatic precipitator. Downstream of the PCD 44 there is provided a wet flue gas desulfurization (WFGD) device, also known as a wet scrubber, for removal of sulfur oxides from the flue gas 28.
• WFGD wet flue gas desulfurization
• the cleaned, scrubbed flue gas may (optionally) be conveyed through a wet ESP 47 for removal of fine particulate or SO3, and then conveyed to stack 48 for discharge to the atmosphere.
• the second equipment configuration in Figure 1 comprises a spray dryer apparatus (SDA) schematically indicated at 50, also known as a dry scrubber, for removal of sulfur oxides from the flue gas 28. Downstream of the SDA 50 there is provided a particulate collection device (PCD) 44, as described above, for removal of particulates from the flue gas 28. The cleaned, scrubbed flue gas is then conveyed to stack 48 for discharge to the atmosphere.
• SDA spray dryer apparatus
• PCD particulate collection device
• the third equipment configuration in Figure 1 comprises a circulating dry scrubber (CDS) schematically indicated at 49, for removal of sulfur oxides from the flue gas 28.
• CDS circulating dry scrubber
• PCD particulate collection device
• PCD 44 may comprise any suitable particulate collection device including, but not limited to, a fabric filter or an electrostatic precipitator as described above.
• the cleaned, scrubbed flue gas is then conveyed to stack 48 for discharge to the atmosphere.
• the fourth equipment configuration in Figure 1 comprises a first particulate removal device in the form of an electrostatic precipitator (ESP) which is schematically indicated at 44.
• ESP 44 is configured to remove fine particulates from flue gas 28.
• CDS circulating dry scrubber
• CDS 49 a circulating dry scrubber
• PCD 44 for removal of any remaining particulates from the flue gas 28.
• PCD 44 may comprise any suitable particulate collection device including, but not limited to, a fabric filter or an electrostatic precipitator as described above.
• the cleaned, scrubbed flue gas is then conveyed to stack 48 for discharge to the atmosphere.
• ESP 44 could be interchangeably replaced with a fabric filter unit.
• the fifth equipment configuration in Figure 1 comprises a first particulate removal device in the form of either a fabric filter or an electrostatic precipitator (ESP) which is schematically indicated at 44.
• FF/ESP 44 is configured to remove fine particulates from flue gas 28.
• SDA spray dryer apparatus
• 50 also known as a dry scrubber
• PCD second particulate collection device
• PCD 44 may comprise any suitable particulate collection device including, but not limited to, a fabric filter or an electrostatic precipitator as described above.
• the cleaned, scrubbed flue gas is then conveyed to stack 48 for discharge to the atmosphere.
• some boilers 12 employ staged combustion wherein only part of the stoichiometric amount of air is provided in the main burner zone 24, with the balance of the air for combustion, together with any excess air required due to the fact that no combustion process is 100 percent efficient, is provided above the burner zone 24 via over fire air (OFA) ports 52.
• OFA over fire air
• one or more suitable iron-bearing compounds, and if so desired one or more suitable halide compounds, are added to the one or more coal pulverizers 20 prior to supplying the pulverized coal to the one or more burners 22.
• the system and apparatus for accomplishing this desired result is also shown in Figure 1 , generally designated 100.
• the system 100 comprises a storage means 120 for temporarily storing the iron-based phosphorus reduction compound, and if so desired the mercury reducing compound, generally designated 1 10; delivery means 130, 135 for conveying the compound 1 10 to a desired location, including valves, seals, etc.
• control means 150 advantageously microprocessor-based control means, which are accessed via an operator via human operator interface (I/O) station 160, which includes display and data collection and storage means as required.
• I/O human operator interface
• the system of the present invention can, in one embodiment, utilize independent storage, delivery and control means (in accordance with those described above) for each individual iron and/or halide compound.
• the system of the present invention can comprise one set of storage, delivery and control means for the iron compounds or compounds utilized herein and one set of storage, delivery and control means (in accordance with those described above) for the halide compound or compounds utilized herein.
• the raw coal 14 to which the iron-based phosphorus reducing compound 1 10 has been added is referred to as 140.
• the iron-based phosphorus reducing compound 1 10 may be provided along with the raw coal 14 via the feeder 18, which permits close control and measurement of the delivery of both raw coal 14 and iron-based phosphorus reducing compound 1 10 into the coal pulverizer 20.
• the iron-based phosphorus reducing compound 1 10 may be provided directly into the coal pulverizer 20 and/or directly into one or more individual burner lines A - F providing the pulverized coal to individual burners 22, with suitable sealing devices against the positive pressure within the coal pulverizer 20 or burner lines A - F.
• the delivery means may be slurry-based or pneumatic as required by the particulars of the iron-based phosphorus reducing compound 1 10 and the amount and location of introduction into the flue gas 28.
• flue gas samples may instead be taken at the location 200 for later laboratory analysis via suitable test methods, which may be inductively coupled plasma - mass spectrometry (ICP-MS).
• ICP-MS inductively coupled plasma - mass spectrometry
• a human operator could then use the operator interface 160 to manually input a desired set-point into control means 150 for the amount of iron-based phosphorus reducing compound 1 10 introduced into the flue gas 28.
• control means 150 for the amount of iron-based phosphorus reducing compound 1 10 introduced into the flue gas 28.
• the amount of iron-based phosphorus reducing compound 1 10 introduced into the flue gas 28 may be simply a function of boiler load or coal feed rate values.
• the present invention utilizes iron (II) oxide.
• the need for a reduction reaction to occur is eliminated and the addition points for the iron (II) oxide of this embodiment are therefore broader then previous embodiments.
• the iron (II) oxide can be added at any suitable point post-combustion and pre-SCR in order to tie up, bind and/or sequester any PO gas present in the flue gas of a boiler, or furnace, prior to arrival at the SCR.
• the iron-based phosphorus reduction compound can be supplied at one or more of the locations G through Q shown in Figure 1 . More particularly, the iron-based phosphorus reduction compound can also be provided into the flue gas 28 at one or more of the following locations:
• G into or below the burner zone 24, in one or more of the front, rear or side walls, via means separate from the burners 22;
• H into the furnace 26 at a location above the burner zone 24, in one or more of the front, rear or side walls;
• the present invention is directed to a system whereby both one or more iron-based compounds and one or more halide compounds are supplied in any manner per the various methods and/or systems described herein.
• each type of compound, or even each separate compound regardless of type can be supplied individually.
• any combination of two or more compounds regardless of type i.e., whether an iron-based compound or a halide compound
• the reduced iron, or iron (II) oxide, of the present invention is able to remove the gas phase phosphorus in the form of iron- phosphorus alloys which upon coming in contact with the over fire air from iron- phosphorus oxide compounds. This significantly reduces the amount of gas phase phosphorus accumulation in an SCR catalyst.
• Another advantage of the present invention is that through addition of iron a significant portion of any phosphorus present will be iron-bound. Iron-bound phosphorus compounds are less leachable thereby minimizing the transfer of phosphorus to an SCR catalyst.
• phosphorus associated with and/or bound to an iron compound ⁇ e.g., an iron oxide
• the present invention is, in one embodiment, directed to the situation where a majority of the phosphorus present in the combustion and/or flue stream is sequestered in a suitable iron-phosphorus- oxygen-containing compound thereby substantially reducing the amount of calcium/phosphorus/oxygen-containing compounds that are able to react with SO x .
• iron-bearing compound and the halide compound of the present invention can be added via separate compounds or can be added via the same compound and can be supplied in any suitable manner, including the manner detailed in the Figure 1 .
• Suitable iron-bearing compounds include, but are not limited to, powderized, solid, aqueous (be it an aqueous-based suspension or aqueous-based emulsion) and/or water soluble or water insoluble forms of iron-bearing compounds including, but not limited to, metallic iron, one or more iron oxides, iron carbonate, iron (II) acetate ⁇ e.g., Fe(C 2 H 3 O 2 ) 2 » 4H 2 O), iron (II) nitrate ⁇ e.g., Fe(NO 3 ) 2 » 6H 2 O), iron (III) nitrate ⁇ e.g., Fe(NO 3 ) 3 » 6H 2 O or Fe(NO 3 ) 3 '9H 2 O), iron (II)
• Suitable halide compounds include, but are not limited to, potassium bromide, potassium chloride, potassium fluoride, potassium iodide, sodium bromide, sodium chloride, sodium fluoride, sodium iodide, calcium bromide, calcium chloride, calcium fluoride, calcium iodide, aluminum bromide, aluminum chloride, aluminum fluoride, aluminum iodide, other metal halides ⁇ e.g., bromides, chlorides, fluorides and/or iodides) with the proviso that the metal is not iron, or any mixture of two or more thereof.
• one or more aqueous reagents can be pumped via positive displacement pumps from a storage tank to the one or more coal feeders where the reagent is sprayed on the coal as the coal passes on a feeder belt upstream of the pulverizers.
• the one or more halide compounds are chosen to be soluble in water, or an aqueous-based solvent.
• Suitable halides soluble halides include, but are not limited to, potassium bromide, potassium chloride, potassium fluoride, potassium iodide, sodium bromide, sodium chloride, sodium fluoride, sodium iodide, calcium bromide, calcium chloride, calcium iodide, aluminum bromide, aluminum chloride, aluminum iodide, or any mixtures of two or more thereof.
• other transition metal halides ⁇ e.g., bromides, chlorides, fluorides and/or iodides) that are not iron halides can be utilized so long as such compounds are, in this embodiment, soluble in water, or an aqueous-based solvent.
• the present invention is advantageous in that it is applicable to both existing SCRs (retrofits) and new SCRs. Additionally, the present invention can be applied to plants that utilize biomass as a fuel source. In one embodiment, implementation of the present invention can be accomplished in a cost- effective manner utilizing low cost hardware designed to supply the necessary iron compound to a combustion process. The present invention also does not affect the current design of boilers and SCRs. [0064] In one embodiment, the amount of iron compound, or compounds, utilized in conjunction with the present invention varies depending upon the phosphorus content in the coal to be burned.
• the present invention is directed to a method and system whereby a stoichiometric excess one or more iron compounds are supplied to any point prior to an SCR. While not wishing to be bound to any one theory, it has been found that by supplying a stoichiometric excess of iron upstream of an SCR, the catalytic activity and/or catalytic lifespan of an SCR catalyst can be unexpectedly increased. As can be seen from the graph of Figure 2, the addition of a stoichiometric excess of one or more iron-based compounds not only protects the SCR catalyst from poisoning via various phosphorus compounds but also increases both the catalytic activity and catalytic lifespan over a period of at least about 2,000 operational hours.
• Figure 2 is a graph plotting the original expected deactivation for a catalyst without the addition of the iron-bearing compound, or compounds, of the present invention versus the actual deactivation of a catalyst with the addition of an iron-bearing compound of the present invention versus the observed deactivation of a catalyst without the addition of the iron-bearing compound, or compounds, of the present invention.
• the y-axis of the graph of Figure 2 is catalytic activity in decimal terms where 0.9 is equivalent to 90 percent activity as measured when compared to unused virgin catalyst as determined using any suitable method for determining catalytic activity known to those of skill in the art.
• the x-axis of the graph of Figure 2 is the number of operational hours that the catalyst in question is exposed to the average operational conditions of a 100 MWe coal plant.
• the present invention achieves either one, or both, of an increase in catalytic activity and/or an increase in catalytic lifespan via the use, introduction and/or delivery of one or more iron-based compounds.
• an increase in either one, or both, of catalytic activity and/or catalytic lifespan of at least about 10 percent is achieved at an operational time of at least about 2,000 hours versus the catalytic activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected to a supply of one or more iron-based compounds as disclosed herein.
• the present invention achieves an increase in either one, or both, of catalytic activity and/or catalytic lifespan of at least about 10 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 12.5 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 15 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 17.5 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 20 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 22.5 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 25 percent is achieved at an operational time of about 2,000 hours, an increase of at least about 27.5 percent is achieved at an operational time of about 2,000 hours, or even an increase of at least about 30 percent is achieved at an operational time of about 2,000 hours versus the catalytic activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected to a supply of one
• the present invention achieves an increase in either one, or both, of catalytic activity and/or catalytic lifespan of at least about 10 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 12.5 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 15 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 17.5 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 20 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 22.5 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 25 percent is achieved at an operational time of about 2,500 hours, an increase of at least about 27.5 percent is achieved at an operational time of about 2,500 hours, or even an increase of at least about 30 percent is achieved at an operational time of about 2,500 hours versus the catalytic activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected to a supply of
• the present invention achieves an increase in either one, or both, of catalytic activity and/or catalytic lifespan of at least about 10 percent, at least about 12.5 percent, at least about 15 percent, at least about 17.5 percent, at least about 20 percent, at least about 22.5 percent, at least about 25 percent, at least about 27.5 percent, or even at least about 30 percent is achieved at an operational time of about 3,000 hours versus the catalytic activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected to a supply of one or more iron-based compounds as disclosed herein.
• the present invention achieves an increase in either one, or both, of catalytic activity and/or catalytic lifespan of at least about 10 percent, at least about 12.5 percent, at least about 15 percent, at least about 17.5 percent, at least about 20 percent, at least about 22.5 percent, at least about 25 percent, at least about 27.5 percent, or even at least about 30 percent is achieved at an operational time of about 3,500 hours, about 4,000 hours, about 4,500 hours, about 5,000 hours, about 6,000 hours, about 7,000 hours, about 7,500 hours, about 8,000 hours, about 9,000 hours, about 10,000 hours, about 1 1 ,000 hours, about 12,000 hours, about 13,000 hours, about 14,000 hours, about 15,000 hours, or even about 16,000 hours versus the catalytic activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected to a supply of one or more iron-based compounds as disclosed herein.
• individual numerical values can be combined to form additional and/or
• the phosphorus content of coal can be determined by various known methods.
• the present invention is not limited to any one range of iron compounds that are utilized. Instead, an excess stoichiometric ratio is utilized.
• the excess stoichiometric ratio of iron to phosphorus is in the range of about 2.5:1 to about 10:1 , or from about 3:1 to about 9:1 , or from about 3.5:1 to about 8:1 , or from about 4:1 to about 7.5:1 , or from about 5:1 to about 7:1 , or from about 5.5:1 to about 6.5:1 , or even about 6:1 .
• individual range values can be combined to form additional and/or non-disclosed ranges.
• the amount of iron compound, or compounds, utilized in conjunction with the present invention is within a given range when the coal utilized is Powder River Basin/Lignite coal.
• the amount of the iron compound, or compounds, to Powder River Basin/Lignite coal is expressed as the amount of iron compound, or compounds, (hereinafter referred to as just "iron” in only this instance) in pounds for every 1 ,000 pounds of coal.
• the amount of iron compound, or compounds, utilized is in the range of about 5 pounds of "iron" per 1 ,000 pounds of coal to about 20 pounds of "iron” per 1 ,000 pounds of coal.
• the amount of iron compound, or compounds, utilized is in the range of about 5.5 pounds of "iron” per 1 ,000 pounds of coal to about 17.5 pounds of “iron” per 1 ,000 pounds of coal, or from about 6 pounds of "iron” per 1 ,000 pounds of coal to about 15 pounds of "iron” per 1 ,000 pounds of coal, or from about 7 pounds of "iron” per 1 ,000 pounds of coal to about 12.5 pounds of "iron” per 1 ,000 pounds of coal, or from about 7.5 pounds of "iron” per 1 ,000 pounds of coal to about 10 pounds of "iron” per 1 ,000 pounds of coal, or even from about 8 pounds of "iron” per 1 ,000 pounds of coal to about 9 pounds of "iron” per 1 ,000 pounds of coal.
• individual range values can be combined to form additional and/or non-disclosed ranges.
• the amount of iron-based compound, or compounds, as compared on a weight basis to the amount of one or more halide compounds is in the range of about 95 weight parts iron based compound, or compounds to about 5 weight parts halide compound, or compounds.
• the weight ratio of iron-based compound, or compounds, to halide compound, or compounds is in the range of about 95:5 to about 75:25, or from about 93.5:6.5 to about 80:20, or from about 92:8 to about 82.5:17.5, or from about 91 :9 to about 85:15, or even from about 90:10 to about 87.5:12.5.
• the amount of the one or more halide compounds, if so utilized, can be calculated based on any of the above stated iron-based compound, or compounds, amounts via the ratios disclosed in this paragraph.
• individual range values can be combined to form additional and/or non-disclosed ranges.
• the injection rate of the one or more halide compounds, if so utilized in conjunction with the present invention, for controlling mercury in a flue gas, or combustion gas is based on a non-limiting example of a 100 MWe coal power plant.
• the injection rate for the one or more halide compounds, if in solution is in the range of about 0.25 gallons per hour to about 10 gallons per hour, or from about 0.5 gallons per hour to about 5 gallons per hour, or even from about 1 gallon per hour to about 4 gallons per hour.
• the one or more halide compounds are supplied at any rate to a flue gas, or combustion gas, sufficient to yield a concentration of halide ⁇ e.g., bromide, chloride or iodide) between about 10 ppm to about 200 ppm, or from about 25 ppm to about 175 ppm, or from about 50 ppm to about 150 ppm.
• halide e.g., bromide, chloride or iodide
• the concentration of halide is between about 10 ppm to about 125 ppm, or from about 25 ppm to about 100 ppm, or from about 50 ppm to about 75 ppm.
• individual range values can be combined to form additional and/or non-disclosed ranges.
• the amount of one or more iron, or iron-based, compounds necessary to supply the desired amount of iron to a flue gas, or combustion gas, in accordance with the process of the present invention will vary depending upon the size of the device generating such flue gas, or combustion gas.
• the same can be said of the one or more halide compounds. That is, one of skill in the art would recognize that the amount of one or more halide compounds necessary to supply the desired amount of halide to a flue gas, or combustion gas, in accordance with the process of the present invention will vary depending upon the size of the device generating such flue gas, or combustion gas.
• the present invention is not limited to any specific rate or range of supply.
• the amount of halide solution (25 weight percent solution) supplied to the flue gas, or combustion gas is in the range of about 0.25 gallons per hour to about 6 gallons per hour, or from 0.5 gallons per hour to about 5 gallons per hour, or even from 1 gallon per hour to about 4 gallons per hour.
• individual range values can be combined to form additional and/or non- disclosed ranges.
• the present invention is not limited to solely these supply rates. Rather, any supply rate can be used in order to achieve the desired concentration of halide.
• additional factors can impact the amount of iron-based, iron-bearing and/or iron compounds supplied in connection with the various embodiments of the present invention.
• additional factors include, but are not limited to, the amount and/or type of phosphorus present in the coal, or other combustible fuel; the size and/or output of the boiler, heater, kiln, or other flue gas-, or combustion gas-, generating device; and the desired stoichiometric ratio to be achieved; the type and/or manner of combustion, the type and/or arrangement of any applicable equipment or structure.
• the one or more iron compounds and/or the one or more halide compounds utilized in conjunction with the present invention can be of any particle size and/or particle geometry.
• Suitable particle geometries include, but are not limited to, spherical, platelet-like, irregular, elliptical, oblong, or a combination of two or more different particle geometries.
• each different compound, or even the same compound can be supplied in the form of one or more particle geometries.
• the one or more iron compounds and/or the one or more halide compounds of the present invention if water soluble, can be supplied in solution form, either independently or together so long as the active components to be delivered to the flue, or combustion, gas do not adversely react.
• a solution concentration of at least about 15 weight percent of one or more water soluble iron compounds and/or one or more water soluble halide compounds is utilized.
• a solution concentration of at least about 20 weight percent, at least about 25 weight percent, at least about 30 weight percent, at least about 35 weight percent, at least about 40 weight percent, at least about 45 weight percent, or even at least about 50 weight percent of more of the one or more water soluble iron compounds and/or the one or more water soluble halide compounds is utilized in conjunction with the present invention.
• individual range values can be combined to form additional and/or non-disclosed ranges.
• the solution concentration of any one or more water soluble iron compounds and/or the one or more water soluble halide compounds should not, in one embodiment, exceed the solubility amount, respectively, for the one or more iron compounds and/or the one or more halide compounds.
• the one or more iron compounds and/or the one or more halide compounds of the present invention can be supplied in a powdered form, a solution form, an aqueous suspension form, or a combination of two or more thereof.
• the one or more iron compounds and/or the one or more halide compounds utilized in conjunction with the present invention should have a suitable particle size.
• the one or more iron compounds and/or the one or more halide compounds of the present invention should have a suitable particle size that facilitates a higher degree of reactivity when placed into contact with a flue, or combustion, gas.
• both of these conditions can be met, whether individually or in combination, by one or more iron compounds and/or one or more halide compounds where at least about 95 percent of the particles have a particle size of less than about 400 ⁇ (microns), where at least about 95 percent of the particles have a particle size of less than about 350 ⁇ (microns), where at least about 95 percent of the particles have a particle size of less than about 300 ⁇ (microns), where at least about 95 percent of the particles have a particle size of less than about 250 ⁇ (microns), where at least about 95 percent of the particles have a particle size of less than about 200 ⁇ (microns), or even where at least about 95 percent of the particles have a particle size of less than about 175 ⁇ (microns).
• individual range values can be combined to form additional and/or non-disclosed ranges.
• a suitable iron compound for use in conjunction with the present invention is iron (II) carbonate available from Prince Agri Products (a subsidiary of Phibro Animal Health Corporation located in Ridgefield Park, New Jersey). This iron (II) carbonate is a powdered compound where at least about 95 percent of its particles are less than 200 ⁇ (microns) in size. Additionally, the concentration of iron (II) carbonate in this product is about 80 percent by weight with substantially all of the remaining 20 weight percent being non-reactive in light of the use here.
• a suitable halide compound for use, if so desired, in conjunction with the present invention is calcium bromide available from Tetra Chemical (located in The Woodlands, Texas).
• such aqueous suspension(s) can further comprise a suitable amount of one or more anti-settling, suspension, thickening or emulsification agents.
• Suitable anti-settling, suspension, thickening or emulsification agents include, but are not limited to, sodium polyacrylates, carbomers, acrylates, and inorganic thickening agents.
• Other suitable anti-settling, suspension, thickening or emulsification agents are known to those of skill in the art and as such a discussion herein is omitted for the sake of brevity.
• a suitable suspension or emulsification can be achieved via agitation and does not necessarily require the use of one or more anti-settling, suspension, thickening or emulsification agents.
• a combination of one or more anti- settling, suspension, thickening or emulsification agents can be utilized in combination with agitation.
• the one or more iron compounds and/or the one or more halide compounds of the present invention should independently have a purity of at least about 50 weight percent, at least about 55 weight percent, at least about 60 weight percent, at least about 65 weight percent, at least about 70 weight percent, at least about 75 weight percent, at least about 80 weight percent, at least about 85 weight percent, at least about 90 weight percent, at least about 95 weight percent, or even at least about 99 weight percent or higher.
• individual range values can be combined to form additional and/or non-disclosed ranges.
• the portion of the one or more iron compounds that is not "an iron compound” such impurities should be non-reactive in the environments present in conjunction with the present invention. Alternatively, if reactive, such impurities should either be easily captured, removed and/or sequestered, or should not add significantly to any further contamination of any catalyst downstream.
• the amount of phosphorus-containing compound impurities in any of the one or more iron compounds and/or the one or more halide compounds that are utilized in conjunction with the present invention should independently be less than about 5 weight percent, less than about 2.5 weight percent, less than about 1 weight percent, less than about 0.5 weight percent, less than about 0.25 weight percent, less than about 0.1 weight percent, or even less than about 0.01 weight percent.
• the amount of phosphorus-containing compound impurities in any of the one or more iron compounds and/or the one or more halide compounds that are utilized in conjunction with the present invention should be zero. That is, in this embodiment the one or more iron compounds and/or the one or more halide compounds that are utilized in conjunction with the present invention should independently be free from any phosphorus-containing compounds.
• the present invention is direct to a system and method for the injection of iron carbonate, another suitable iron compound, or a blend of one or more iron compounds and one or more non-iron-containing halide compounds with coal in the furnace in order to replenish the active catalytic sites on the surface of SCR catalyst with Fe active sites while simultaneously achieving mercury oxidation.
• the injection material is a blend of iron carbonate (about 90 percent by weight) and a non-iron-containing halogen compound ⁇ e.g., calcium bromide 10 percent by weight).
• any iron that is present in coal ash is not catalytically active as it bonds, or is bonded, with various silicates and/or aluminates in the coal combustion process.
• PRB coal more than 90 percent of total iron occurs as a bonded mineral meaning that it is mostly trapped in glassy silica and/or alumina compounds during the combustion process thereby making it unavailable for any other chemical reaction.
• the present invention by injecting iron separately, provides "free" iron that, while not wishing to be bound to any one theory, is believed to settle onto and/or be deposited onto the surface of fly ash which makes it available for further chemical reactions.
• This blended material that contains "free" iron as defined above can then provide iron for increasing the catalytic activity and/or catalytic lifespan of the DeNOx catalyst while, if so provided, the halogen portion of the one or more halide compounds of the present invention acts to aid, or achieve, mercury oxidation. While not wishing to be bound to any one theory, is believed that when the fly ash gets deposited on the surface of SCR catalyst the iron on the surface of fly ash or iron deposited on catalyst as a result of the injection process provides sites onto which ammonia and NO x can react to form N 2 and water.
• any active iron sites that become depleted are replaced by new iron sites at a reasonable rate thereby allowing for the extension and/or increase of catalytic lifespan and/or catalytic activity when compared to similar untreated catalyst as explained in detail above.
• the halogen portion of the halide compound, or compounds oxidizes elemental mercury into its oxidized form and makes it easier for removal by a downstream wet or dry scrubber, or with PAC injection.
• Figure 2 illustrates catalyst performance with and without iron injection.
• the upper line plot (the one with the lower case "Xs") is the originally expected catalyst deactivation curve. This catalyst is expected to last for about 16,000 hours of operation.
• the lower plot (diamonds) illustrates the actual performance for this catalyst. The catalyst actually lasts for only 6,800 hours of operation due to phosphorus deactivation.
• the middle line (triangles) illustrates the performance of a catalyst subjected to at least the iron compound injection of the present invention.
• the catalyst in this example is not new when it is installed but is regenerated catalyst with 15 percent lower initial activity than virgin catalyst.
• the present invention provides additional sites for the DeNO x reaction by injection of one or more iron-bearing compounds thereby making it possible to significantly improve the life and/or catalytic activity of an SCR catalyst beyond presently accepted, or believed, time spans.
• the one or more halide compounds of the present invention provide a halogen component that permits for increased mercury oxidation and makes possible mercury removal downstream by any suitable technology ⁇ e.g., AQCS equipment).
• the present invention seeks to at a minimum control the amount of gas phase selenium and/or the nature of the selenium speciation in at least one of the flue gas or an aqueous environment found in one or more emission control devices ⁇ e.g., a WFGD) via the addition of at least one metal compound at any point described herein with regard to the aforementioned iron- bearing compound.
• emission control devices e.g., a WFGD
• the present invention relates to a method and apparatus for controlling, mitigating and/or reducing the amount of selenium contained in and/or emitted by one or more pieces of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) via the addition of at least one metal compound at any point described herein with regard to the aforementioned iron-bearing compound.
• one or more pieces of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) via the addition of at least one metal compound at any point described herein with regard to the aforementioned iron-bearing compound.
• the present invention relates to method and apparatus for controlling the selenium speciation in one, or both, of a gas phase or a aqueous phase by the addition of at least one metal ⁇ e.g., an aluminum metal additive, or a transition metal additive such as iron, nickel, zinc, copper or other transition metal) additive upstream of either a wet flue gas desulfurization (WFGD) unit and/or a dry flue gas desulfurization (DFGD) unit (i.e., also known as semi-dry flue gas desulfurization units which include, but are not limited to, spray dry absorbers (SDAs), circulating dry scrubbers (CDSs), etc.).
• WFGD wet flue gas desulfurization
• DFGD dry flue gas desulfurization
• SDAs spray dry absorbers
• CDSs circulating dry scrubbers
• the present invention seeks to at a minimum control the amount of gas phase selenium and/or the nature of the selenium speciation in at least one of an amine-based post combustion CO 2 capture processes.
• an amine-based post combustion CO 2 capture processes the amine utilized therein will start to degrade due to being subjected to SO 2 , CO 2 , heat, O 2 , and other degradation products. Due to the large amine volume, or inventory, needed for a post combustion CO 2 capture process, the amine degradation volume is very large and requires the amine to be regenerated to make operation more economical. This is generally done via a thermal reclaimer, which creates a large volume of thermal sludge and/or waste product.
• Suitable metal compounds include water soluble or water insoluble compounds, be they inorganic or organic compounds, of iron, aluminum, nickel, zinc, copper, or mixtures of two or more thereof.
• Suitable iron-bearing compounds include, but are not limited to, powderized, solid, aqueous (be it an aqueous-based suspension or aqueous-based emulsion) and/or water soluble forms of iron-bearing compounds including, but not limited to, metallic iron, one or more iron oxides, iron carbonate, iron (II) acetate (e.g., Fe(C 2 H 3 O 2 ) 2 * H 2 O), iron (II) nitrate (e.g., Fe(NO 3 ) 2 -6H 2 O), iron (III) nitrate (e.g., Fe(NO 3 ) 3 -6H 2 O or Fe(NO 3 ) 3 -9H 2 O), iron (II) sulfate (e.g., FeSO 4 » H 2 O, FeSO 4
• Suitable aluminum-bearing compounds include, but are not limited to, powderized, solid, aqueous (be it an aqueous-based suspension or aqueous-based emulsion) and/or water soluble or water insoluble forms of aluminum-bearing compounds including, but not limited to, metallic aluminum, aluminum acetate (e.g., AI(C 2 H 3 O 2 ) 3 ), aluminum bromate (e.g., AI(BrO 3 ) 3 » 9H 2 O), aluminum bromide (e.g., AIBr 3 , AI 2 Br 6 , AIBr 3 » 6H 2 O or AIBr 3 » 15H 2 O), aluminum chloride (e.g., AICI3, AI 2 Cl6 or AICI 3 » 6H 2 O), aluminum fluoride (e.g., AIF 3 , AIF 3 » 31 ⁇ 2H 2 O or AIF 3 » H 2 O), aluminum hydroxide (e.g., AI(OH) 2 ), aluminum iodide (e.g.,
• Suitable nickel-bearing compounds include, but are not limited to, powderized, solid, aqueous (be it an aqueous-based suspension or aqueous-based emulsion) and/or water soluble or water insoluble forms of nickel-bearing compounds including, but not limited to, metallic nickel, nickel acetate (e.g., Ni(C 2 H 3 O 2 ) 2 or Ni(C 2 H 3 O 2 ) 2 » 4H 2 O), nickel bromate (e.g., Ni(BrO 3 ) 2 » 6H 2 O), nickel bromide (e.g., NiBr 2 or NiBr 2 » 3H 2 O), nickel carbonate or basic nickel carbonate (e.g., NiCO 3 , 2NiCO 3 » 3Ni(OH) 2 » 4H 2 O or zaratite), nickel chloride (e.g., NiCI 2 or NiCI 2 » 6H 2 O), nickel fluoride (e.g., NiF 2 ), nickel hydroxide (e.g.
• Suitable copper-bearing compounds include, but are not limited to, powderized, solid, aqueous (be it an aqueous-based suspension or aqueous-based emulsion) and/or water soluble or water insoluble forms of copper-bearing compounds including, but not limited to, metallic copper, copper acetate (e.g., Cu(C 2 H 3 O 2 ) 2 'CuO'6H 2 O or Cu(C 2 H 3 O 2 ) 2 » H 2 O), copper bromate (e.g., Cu(BrO 3 ) 2 » 6H 2 O), copper bromide (e.g., CuBr, Cu 2 Br 2 or CuBr 2 ), copper trioxybromide (e.g., CuBr 2 » 3Cu(OH) 2 ), copper carbonate or basic copper carbonate (e.g., Cu 2 CO 3 , CuCO 3 » Cu(OH) 2 or 2CuCO 3 » Cu(OH) 2 ), copper chloride (e.g., CuCI,
• Suitable zinc-bearing compounds include, but are not limited to, powderized, solid, aqueous (be it an aqueous-based suspension or aqueous-based emulsion) and/or water soluble or water insoluble forms of zinc-bearing compounds including, but not limited to, metallic zinc, zinc acetate (e.g., Zn(C 2 H 3 O 2 ) 2 or Zn(C 2 H 3 O 2 ) 2 » 2H 2 O), zinc bromate (e.g., Zn(BrO 3 ) 2 » 6H 2 O), zinc bromide (e.g., ZnBr 2 ), zinc carbonate (e.g., ZnCO 3 ), zinc chloride (e.g., ZnCI 2 ), zinc ferrate (e.g., ZnFe 2 O 4 ), zinc fluoride (e.g., ZnF 2 or ZnF 2 » 4H 2 O), zinc hydroxide (e.g., Zn(OH) 2 ), zinc io
• the present invention can entail the use of at least one kaolin-bearing compound to control gas phase sodium and potassium compounds as described in United States Patent No. 8,303,919 the complete disclosure and teachings of which are hereby incorporated herein by reference in their entirety.
• the present invention is, in one embodiment, directed to a method and/or apparatus that enables one to control either one, or both, of gas phase selenium or aqueous selenium in one or more emission control devices/equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices.
• the addition of the one or more metal-bearing compounds permits the gas phase and/or aqueous phase capture of selenium via modification of the selenium speciation thereby resulting in a selenium compound having a lower solubility in water, or other aqueous solutions, than would otherwise occur without the addition of the one or more metal-bearing compounds of the present invention.
• the present invention is application to both WFGD and DFGD systems and permits the control, mitigation, and/or reduction of selenium in, for example, the effluent of a WFGD, the slurry solution of a WFGD, the particulate matter resulting from a DFGD, etc.
• the present invention achieves a modification of the selenium speciation in a gas phase and/or a liquid/aqueous phase to an oxidation state and/or selenium compound ⁇ e.g., including, but not limited to, an insoluble selenite compound and/or an insoluble selenide compound, etc.) having a low solubility (herein defined as a solubility of less than about 0.1 grams per 100 mL, less than about 0.01 grams per 100 mL, less than about 0.001 grams per 100 mL, less than about 0.0001 grams per 100 mL, less than about 1 x 10 "5 grams per 100 mL, or less than about 1 x 10 "6 grams per 100 mL in water at SATP); essentially no solubility (herein defined as a solubility of less than about 1 x 10 "7 grams per 100 mL, less than about 1 x 10 "8 grams per 100 mL, or even less than about
• SATP is known as "standard ambient temperature and pressure" and is defined herein to be equivalent to a temperature of 298.15 K ⁇ i.e., 25°C or 77°F) and an absolute pressure of 100 kPa ⁇ i.e., 14.504 psi or 0.986 atm).
• standard ambient temperature and pressure is defined herein to be equivalent to a temperature of 298.15 K ⁇ i.e., 25°C or 77°F) and an absolute pressure of 100 kPa ⁇ i.e., 14.504 psi or 0.986 atm).
• individual numerical values can be combined to form additional and/or non- disclosed ranges.
• the present invention's selenium control can be accomplished with, or without, one or more of: (i) the control of mercury in the flue gas via mercury oxidation and capture using any suitable mercury control technology discussed herein; (ii) the control of one or more of gas phase sodium and/or gas phase sodium compounds; and/or (iii) the control of one or more of gas phase potassium and/or gas phase potassium compounds.
• the present invention utilizes at least one iron-bearing compound to simultaneously control gas phase phosphorus and gas phase and/or aqueous selenium as described above.
• the amount of iron-bearing compound that is supplied in any manner and at any position discussed previously can be the same amount discussed above with regard to the control of gas phase phosphorus.
• the amount of iron- bearing compound, or other metal-bearing compound, supplied in accordance with this embodiment of the present invention is not limited to any one amount.
• an excess stoichiometric ratio can be utilized.
• the excess stoichiometric ratio of metal ⁇ e.g., iron, aluminum, nickel, zinc and/or copper via the one or more metal-bearing compounds) to selenium is in the range of about 2.5:1 to about 10:1 , or from about 3:1 to about 9:1 , or from about 3.5:1 to about 8:1 , or from about 4:1 to about 7.5:1 , or from about 5:1 to about 7:1 , or from about 5.5:1 to about 6.5:1 , or even about 6:1 .
• the amount of the one or more iron-bearing compounds of the present invention that are utilized to remove gas phase phosphorus and/or one or more gas phase phosphorus compounds are within the scope of the one or more ranges detailed above in connection with the various coal- based embodiments of the present invention.
• the present invention relates to a process for reducing the impact of one or more gas phase compounds such as phosphorus, sodium, and/or potassium compounds on the catalytic activity of an SCR catalyst.
• the same types of compounds as described above with regard to the various coal embodiments detailed above, as well as the same amounts thereof, can be utilized to control one or more gas phase phosphorus, sodium, and/or potassium compounds during the combustion of other types of fossil fuels ⁇ e.g., fuel oil).
• the present invention relates to the use of the various embodiments described above with regard to the control of one or more gas phase phosphorus, sodium, and/or potassium compounds, as well as the control of one or more of mercury and/or selenium in connection with the combustion of any type of fossil fuel ⁇ e.g., fuel oil).
• the types of compounds utilized to control such one or more gas phase compounds, mercury and/or selenium are similar to the embodiments detailed above and apply equally to any of the other fossil fuel embodiments of the present invention.
• the present invention relates to a method for controlling the selenium speciation in a flue gas and/or in at least one piece of emission control equipment, the method comprising the steps of: (a) providing at least one metal-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; and (b) permitting the at least one metal-bearing compound to react with any selenium and/or selenium compounds present in the combustion zone, flue gas, gas phase and/or at least one piece of emission control equipment, wherein the method permits the control of the selenium speciation in one or more of the gas phase and/or in the at least one piece of emission control equipment thereby resulting in a reduction in the amount of selenium emitted in a flue gas and/or from one or more pieces of emission control equipment, wherein the at least one metal-
• the present invention relates to a method for controlling the selenium speciation in a flue gas and/or in at least one piece of emission control equipment in conjunction with a post combustion CO 2 capture process, the method comprising the steps of: (I) providing at least one metal-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; and (II) permitting the at least one metal-bearing compound to react with any selenium and/or selenium compounds present in the combustion zone, flue gas, gas phase and/or at least one piece of emission control equipment, wherein the method permits the control of the selenium speciation in one or more of the gas phase and/or in the at least one piece of emission control equipment thereby resulting in a reduction in the amount of selenium emitted in a flue gas, from one or more pieces of emission control equipment and/or in at least one amine compound that is utilized in conjunction with the post combustion CO 2 capture process.
• the present invention relates to a method for simultaneously increasing the active life of an SCR catalyst and controlling the selenium speciation in a flue gas and/or selenium speciation in at least one piece of emission control equipment, the method comprising the steps of: (A) providing at least one iron-bearing compound to a combustion zone or flue gas stream of a furnace, or boiler, prior to entry of the flue gas into an SCR; and (B) simultaneously permitting the at least one iron-bearing compound to react with any gaseous phosphorus compounds, or phosphorus-containing compounds, present in the combustion zone or flue gas as well as any selenium and/or selenium compounds present in the combustion zone, flue gas, gas phase and/or at least one piece of emission control equipment prior to the entry of the flue gas into the SCR, wherein the method achieves an increase in either one, or both, of a catalytic activity and/or a catalytic lifespan of at least about 10 percent at an operational time of at least about

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• 2014
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