US20070113468A1 - Method for combustion of pulverized coal with reduced emissions - Google Patents

Method for combustion of pulverized coal with reduced emissions Download PDF

Info

Publication number
US20070113468A1
US20070113468A1 US11/657,305 US65730507A US2007113468A1 US 20070113468 A1 US20070113468 A1 US 20070113468A1 US 65730507 A US65730507 A US 65730507A US 2007113468 A1 US2007113468 A1 US 2007113468A1
Authority
US
United States
Prior art keywords
oxygenate
heat
glycerol
oil
coal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/657,305
Inventor
Donald Appleby
Joia Spooner-Wyman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US11/657,305 priority Critical patent/US20070113468A1/en
Publication of US20070113468A1 publication Critical patent/US20070113468A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10LFUELS 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
    • C10L5/00Solid fuels
    • C10L5/02Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
    • C10L5/34Other details of the shaped fuels, e.g. briquettes
    • C10L5/36Shape
    • C10L5/366Powders
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10LFUELS 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
    • C10L9/00Treating solid fuels to improve their combustion
    • C10L9/10Treating solid fuels to improve their combustion by using additives

Definitions

  • the present invention relates to a method of combusting coal for the generation of heat and power that results in reduced emission of oxides of nitrogen (NOx) which consists of a co-firing pulverized coal, preferably in a boiler or furnace system, with an effective amount of an oxygen-containing organic compound.
  • NOx oxides of nitrogen
  • coal Being the least expensive and available in relative abundance, coal is the preferred fuel in many instances. Unfortunately however, the combustion of coal generates substantial quantities of harmful pollutants, such as sulfur dioxide, oxides of nitrogen, carbon monoxide and particulates. Fuels other than coal often have fewer effects on air quality, but tend to be more expensive, or be in relatively short supply.
  • Environmental legislation such as the Clean Air Act in the United States, has been enacted in many countries to control the amount of various chemicals released into the atmosphere in an effort to protect human health and the environment.
  • industry is typically regulated by state or regional environmental protection agencies that set limits as to the amounts of airborne pollutants that can be emitted from a given source.
  • staged combustion to reduce NOx wherein there are more than one individualized combustion zones in the furnace. While this technique is suitable for the construction of a new furnace, it is not easily or inexpensively retrofitted to existing furnaces.
  • Another method of reducing NOx emissions is to combine another fuel having less NOx emissions per heating unit value, such as fuel oil, in a furnace or boiler, with the coal. Such combination can reduce the overall NOx emissions while providing the same or similar overall heating values.
  • this method often permits coal-burning facilities to meet air quality regulations, it is simply a substitution of a more expensive, but less NOx emitting fuel for the coal.
  • the fuel oil does not actually reduce the emissions of the coal itself, but rather, reduces the emissions from the heating system itself.
  • the present invention relates to fuel compositions providing reduced emissions of NOx when combusted, wherein the composition comprises:
  • an oxygenate selected from the group consisting of, glycerol, glycerol derivatives, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, fatty acid alkyl esters, fatty alcohols, and mixtures thereof.
  • the present invention also relates to methods of reducing the NOx emissions generated from the burning of pulverized coal in a heat-producing unit, wherein said method comprises the steps of:
  • compositions and methods of the present invention can include, consist essentially of, or consist of, the components of the present invention as well as other ingredients described herein.
  • “consisting essentially of” means that the composition or component may include additional ingredients, but only if the additional ingredients do not materially alter the basic and novel characteristics of the claimed compositions or methods.
  • Fuel-bound nitrogen is the source of approximately 80% of the NOx emissions from uncontrolled combustion of pulverized coal.
  • the co-firing of the coal with oxygenate functions to reduce the conversion of fuel bound nitrogen to NOx.
  • the oxygenated fuel pyrolyzes faster than the coal, thereby consuming oxygen and creating a locally fuel rich zone around the firing source. In this fuel rich zone, it is speculated that nitrogen-containing molecules desorb from the coal and in the absence of excess oxygen, these nitrogen compounds are reduced to N 2 .
  • reduced emissions of NOx and particulates are achieved when the pulverized coal is co-fired with a selected oxygenate source.
  • the NOx-reducing fuel compositions and methods herein may also include a wide variety of other ingredients/steps.
  • the compositions and methods of the present invention are described in detail hereinafter.
  • pulverized coal refers to a lignite, anthracite and/or bituminous coal that is either already small enough or has been subjected to mechanical particle size reduction such that the resulting “pulverized” material can be conveyed via fluidization with air through a pipe into the combustion chamber of a furnace or boiler.
  • the pulverized coal useful herein is at least 50% under 200 mesh (74 microns), more preferably the coal useful herein is at least 60% under 200 mesh, and even more preferably, at least 70% under 200 mesh.
  • oxygenate source refers to an organic compound consisting primarily of hydrogen, carbon and oxygen atoms.
  • Oxygenate sources useful herein include glycerine and/or glycerol derivatives, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, methyl esters of natural fats and oils (biodiesel), fatty alcohols of natural fats and oils, and mixtures thereof.
  • the natural fats and oils themselves and/or the fatty acids derived from such fats and oils may be optionally added as a secondary oxygenate source to one or more of the oxygenated sources.
  • reduced emissions of NOx are achieved when pulverized coal is co-fired in a combustion chamber of, for instance, a furnace or boiler, in conjunction with an effective amount of an oxygenate source.
  • the oxygenate source material is co-fired with the pulverized coal such that the oxygenate source material accounts for from about 2.5% to about 40% on a heat input basis, of the heat output generated. More preferably, the oxygenate source material accounts for from about 10% to about 20%, on a heat input basis, of the heat output generated.
  • Co-firing may occur by blending the oxygenate source with the coal prior to, during, and/or after pulverization, or may be injected into the combustion zone via a separate nozzle.
  • the oxygenate source of the present invention may be selected from glycerine and/or glycerol derivatives.
  • glycerine or “glycerol” can be used interchangeably and refer to 1,2,3 hydroxypropane or 1,2,3, propanetriol.
  • Glycerine is typically produced as a co-product from the production of soaps, fatty acids, fatty alcohols and alkyl esters. Glycerine from these sources is commonly referred to as “natural glycerine”.
  • Another possible source of natural glycerine is from the hydrogenation or enzymatic conversion of glucose, sorbitol or other sugars to glycerine and other polyols.
  • glycerine is produced from propylene, typically through the allyl chloride to epichlorohydrin process as practiced by Dow Chemical. Glycerine from any source, or combination of sources may be used herein.
  • glycerol derivatives preferred for use herein include ethers in which 1 to 3 of the glycerol hydroxyl groups have been etherified.
  • a wide range of olefins may be used to etherify the glycerol.
  • olefin refers to an unsaturated straight, branched or cyclic hydrocarbon of C 2 -C 10 .
  • olefins useful herein include ethylene, propylene, butylenes, isobutylene, pentene, cyclopentene, isopentene, hexane, cyclohexene, 3-methylpentene, 2,2-dimethylbutene, 2,3-dimethyl butene, 1-heptene, 2-heptene, 3-heptene, I-octene, 2-octene, 3-octene, 4-octene, 1-nonene, 2-nonene, 3-nonene, 4-nonene, 1-decene, 2-decene, 3-decene, 4-decene, 5-decene and the like.
  • C 2 -C 6 olefins are preferred due to their low cost.
  • Mixtures of olefins can be employed, for example if the glycerol were reacted with a mixture of olefins in unpurified form.
  • glycerol derivative that is useful herein is the reaction product of glycerol and acetone having the formula 2,2-dimethyl-1,3-dioxolane-4-methanol, commonly called solketal.
  • the glycerol derivative of the present invention is selected from di t-butyl glycerol ethers, tri t-butyl glycerol ethers, solketal, or mixtures thereof. More preferably, the glycerol derivative is a mixture of di t-butyl and tri t-butyl glycerol ethers comprised roughly of 80% di t-butyl glycerol and 20% tri t-butyl glycerol.
  • Typical catalysts include organic acid catalysts such as para-toluenesulfonic acid, acidic ion exchange resins such as Amberlyst 15 or the class of crystalline metallosilicates known as zeolite catalysts. Catalyst levels should range between 0.1 and 5 wt % of polyol.
  • Typical reaction temperatures range from about 50° C. to about 200 ° C., preferably from about 50° C. to about 150° C., and more preferably from about 50° C. to about 100 ° C.
  • Typical reaction pressures range from about 40 psig to about 1000 psig, preferably from about 40 psig to about 300 psig and more preferably from about 50 psig to about 150 psig.
  • Typical olefin:polyol molar ratios range from about 1:1 to about 5:1, preferably from about 2:1 to about 3:1.
  • Typical reaction times are from about 2 to about 24 hours, preferably from about 2 to about 10 hours, and more preferably from about 2 to about 6 hours. Reaction according to this synthesis process proceeds to about 95% polyol conversion. Separation of the mono-, di- and tri-ethers may be accomplished by appropriate steps, such as liquid-liquid extraction.
  • the oxygenate source of the present invention may be selected from propylene glycol or derivatives thereof.
  • Propylene glycol derivatives useful herein include dipropylene glycol and polypropylene glycol having a molecular weight of from about 200 to about 1,000, e.g., polypropylene glycol 400.
  • propylene glycol derivatives herein include: glycol ethers such as mono, di, tri propylene glycol butyl ether; mono, di, tripropylene glycol methyl ether; mono, di, tripropylene glycol tertiary butyl ether; mono, di, tripropylene glycol ethyl ether; mono, di tripropylene glycol propyl ether; mono, di, tripropylene glycol pentyl ether; mono, di, tripropylene glycol hexyl ether; and mono, di tripropylene glycol propionate.
  • glycol ethers such as mono, di, tri propylene glycol butyl ether
  • mono, di, tripropylene glycol methyl ether mono, di, tripropylene glycol tertiary butyl ether
  • mono, di, tripropylene glycol ethyl ether mono, di tripropylene glycol propyl ether
  • the oxygenate source of the present invention may be selected from ethylene glycol and derivatives thereof.
  • Ethylene glycol derivatives useful herein include diethylene glycol and polyethylene glycol having a molecular weight of from about 200 to about 1,000, e.g., polyethylene glycol 400.
  • ethylene glycol derivatives herein include: glycol ethers such as ethylene glycol monobutyl ether (butyl cellosolve); diethylene glycol monobutyl ether (butyl carbitol); triethylene glycol monobutyl ether; tetraethylene glycol monobutyl ether; ethylene glycol hexyl ether; diethylene glycol hexyl ether; ethylene glycol ethyl ether; ethylene glycol methyl ether; ethylene glycol propyl ether; ethylene glycol pentyl ether; diethylene glycol methyl ether; diethylene glycol ethyl ether; diethylene glycol propyl ether; diethylene glycol pentyl ether; triethylene glycol methyl ether; triethylene glycol methyl ether; triethylene glycol propyl ether; triethylene glycol pentyl ether; triethylene glycol hexyl ether; and ethylene glycol acetate.
  • the oxygenate source of the present invention may be selected from fatty acid alkyl esters, also commonly referred to as “biodiesel” fuels.
  • alkyl herein refers to a saturated straight, branched or cyclic hydrocarbon of C 1 -C 10 , and includes methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, cyclopentyl, isopentyl, neopentyl, hexyl, hextyl, octyl, nonyl, decyl and combinations thereof.
  • oils and fats derived from animals and plants may be used as the source of such fatty acid alkyl esters.
  • oils and fats useful herein include beef tallow, coconut oil, corn oil, cottonseed oil, lard, olive oil, palm oil, palm kernel oil, peanut oil, soybean oil, linseed oil, tung oil, sunflower oil, safflower oil, canola oil, rapeseed oil, sesame oil, babassu oil, perilla oil, oiticica oil, fish oils, menhaden oil, castor oil, chinese tallow tree oil, physic nut oil, cuphea seed oil, microalgal oils, bacterial oils and fungal oils.
  • oils can be used as the source of fatty acid alkyl esters in the present invention, it is particularly applicable to soybean oil, canola oil, rapeseed oil, sunflower oil and recycled (waste) cooking oil or grease.
  • the fatty acid alkyl esters used herein are selected from the methyl esters of soybean oil, yellow grease, rapeseed oil, and mixtures thereof.
  • the oxygenate source of the present invention may be selected from fatty alcohols of oils and/or fats.
  • oils and fats derived from animals and plants may be used as the source of such fatty alcohols.
  • oils and fats useful herein include beef tallow, coconut oil, corn oil, cottonseed oil, lard, olive oil, palm oil, palm kernel oil, peanut oil, soybean oil, linseed oil, tung oil, sunflower oil, safflower oil, canola oil, rapeseed oil, sesame oil, babassu oil, perilla oil, oiticica oil, fish oils, menhaden oil, castor oil, chinese tallow tree oil, physic nut oil, cuphea seed oil, microalgal oils, bacterial oils and fungal oils. While a wide range of oils, or mixture of oils, can be used as the source of fatty alcohols in the present invention, it is particularly applicable to coconut, palm kernel, palm, tallow, and mixtures thereof.
  • oxygenates useful herein may be included in the co-firing herein as secondary oxygenates. Such materials may further reduce NOx emissions.
  • oils and fats derived from animals and plants may be used.
  • oils and fats useful herein include beef tallow, coconut oil, corn oil, cottonseed oil, lard, olive oil, palm oil, palm kernel oil, peanut oil, soybean oil, linseed oil, tung oil, sunflower oil, safflower oil, canola oil, rapeseed oil, sesame oil, babassu oil, perilla oil, oiticica oil, fish oils, menhaden oil, castor oil, chinese tallow tree oil, physic nut oil, cuphea seed oil, microalgal oils, bacterial oils and fungal oils.
  • Fatty acids derived from any of these oils and/or fats or combinations thereof may be useful herein as secondary oxygenates. While a wide range of oils, or mixture of oils, can be used as the source of fatty acids in the present invention, it is particularly applicable to soybean oil, tallow, recycled (waste) cooking oil or grease.
  • heat-producing unit refers to a combustion unit in which coal is burned to generate heat energy. The heat energy generated may then be used to heat water or produce steam, such as in a boiler or furnace. Suitable heat producing units include furnaces and boilers wherein pulverized coal is burned. This heat can be used to produce steam for driving electricity-producing turbines or to supply heat to operate a manufacturing process or to provide heat for buildings and structures.
  • the boilers useful in the methods of the present invention will preferably include at least one of the following and may include, for example, an air supply system, water supply and cooling system, a combustion chamber, fuel supply systems, a flue-gas cooling chamber, scrubber, an air induced-draft fan, a stack, or combinations of any two or more of these features.
  • the burner is a low NOx burner wherein the system is already optimized for the lowest NOx emissions possible for use with pulverized coal fuel.
  • the primary air flow there must be one air source available to the burner which is commonly referred to as the “primary air flow.”
  • additional air flow may be a secondary and/or tertiary air flow.
  • additional air flows may include overfire air, underfire air, curtain air, or mixtures thereof.
  • primary air comes into the burner with the coal
  • secondary and tertiary air follows.
  • there is an overfire air downstream that is located a distance away from the burner that is 65% of the distance to the flue gas sampling port.
  • the Stoichiometric Ratio is the actual air/theoretical air for complete combustion of the coal.
  • the burner air is distributed as follows:
  • the stoichiometric ratio is preferably at least about 0.8 in order to reduce corrosion and/or deposits of undesirable by-products.
  • co-firing refers to a process or method by which a secondary fuel (here an oxygenate source) is injected into the combustion chamber of a heat-producing unit at the same and/or similar times as a primary (here, pulverized coal) fuel in order to burn at least somewhat concurrently.
  • a secondary fuel here an oxygenate source
  • the two fuels are preferably introduced into the combustion chamber,through a separate injection device or system.
  • Pollutant-emission levels can be maintained at or below regulated limits by evaluating the respective pollutant-emission concentrations produced by the oxygenate and by the coal.
  • the energy producer can then calculate the concentration ratio of the oxygenate and the fuel(s) that will produce a desired emission concentration (e.g., an emission concentration within the regulated limit) for the NOx (or other pollutant) then burn at least that much oxygenate in combination with the pulverized coal.
  • the necessary concentration of the oxygenate may be calculated based on its percentage heat input as a function of the overall (fixed) heat input of the combined fuels.
  • the term “co-firing ratio” refers to the percentage of total heat generated from the combustion of the oxygenate source.
  • the co-firing ratio of oxygenate source to coal is from about 2.5% to about 50%, preferably from about 10% to about 30%.
  • the oxygenate source is in liquid form and is fed through a dual fluid nozzle that atomizes the premixed fuel/air.
  • the liquid port is separated from the coal port, but injected substantially simultaneously.
  • the methods of the present invention do not require additional equipment modifications or after treatment devices such as air-staging, scrubbers, Selective Non-Catalytic Reduction units, or Selective Catalytic Reduction units in order to benefit from the NOx emissions reductions.
  • equipment modifications or after-treatment devices may be incorporated into the methods of the present invention if so desired, to further reduce NOx emissions.
  • air staging refers to the known method of introducing combustion air in “stages” along the combustion zone as opposed to all the air being introduced at the point coal enters the furnace.
  • staged combustion techniques that may further reduce nitrogen oxide emissions from the combustion of fuels containing nitrogen. For example, See, U.S. Pat. No. 3,727,562; U.S. Pat. No. 4,343,606; and references cited therein.
  • Selective Catalytic Reduction Units are a post-combustion NOx-controlling technology that are theoretically capable of providing NOx reductions in excess of 90% (realistically greater than 50% as of today). NOx reductions are achieved by injecting ammonia and/or urea into the flue gas, which then passes through layers of catalyst in a reactor. The ammonia and/or urea react with the NOx on the surface of the catalyst, forming molecular nitrogen and water.
  • the methods of the present invention include a further step of treating the flue gas with an optional modification selected from air staging, selective non-catalytic reduction units, selective catalytic reductions, scrubbers, and combinations thereof.
  • an optional modification selected from air staging, selective non-catalytic reduction units, selective catalytic reductions, scrubbers, and combinations thereof.
  • any known modification or methodology associated with heat-producing units may be added to the methods of the present invention.
  • Combustion system A pulverized coal combustion test furnace, referred to as the “L1500”, is a nominal 5 MM BTU/hr (1.5 MW) furnace designed to simulate commercial combustion conditions.
  • the inner dimensions of the horizontal-fired combustor are 42 ⁇ 42 inches square and 40 feet long.
  • the walls have multiple layered insulation to reduce the temperature from about 3000° F. on the fire-side to below 140° F. on the shell side.
  • the combustor is modular in design, and is made up of 12 sections with numerous access ports and optional cooling panels in each section. This allows the flue gas temperature profile to be adjusted to better simulate commercial equipment.
  • the access ports are used for visual observations, fuel and or air injection, and product sampling.
  • the overall combustion facility includes the air supply system, water supply system and cooling system, L1500 combustor, fuel supply systems, a flue-gas cooling chamber, scrubber, and induced-draft fan and a stack.
  • the burner in the L1500 is a low NOx design, having primary, secondary and tertiary air inputs that can be independently controlled in terms of flow rate, preheat temperature and, for the secondary and tertiary air registers, degree of swirl. Overfire air is injected downstream in the furnace.
  • Coal is injected into the furnace through the center of the burner.
  • the coal injector consists of a 1.5 inch pipe inside a 3-inch pipe. Coal is fed through the annulus between the two pipes; the 1.5-inch pipe acts as a bluff body.
  • the burner system is modified to allow injection of liquid fuel.
  • a dual-fluid (oil+air) atomizing nozzle is inserted through the 1.5-inch bluff body pipe in the center of the burner so that the tip of the nozzle is set back approximately one inch from the end of the 1.5-inch pipe.
  • Liquid fuel and air are premixed and fed through six small holes in the injector tip.
  • the liquid fuel is fed from two 10-gallon pressure tanks connected in parallel, Compressed air is applied to the tanks, which forced the liquid out from the tanks, through a digital flow meter and into the burner. Adjusting the air pressure could vary the liquid flow rate.
  • Samples can be taken from any two locations in the furnace. For the data herein, they are pulled from Section 6 which corresponds to approximately a two second residence time and is representative of an industrial pulverized coal boiler. Samples are also taken at the furnace outlet, corresponding to about 5 seconds residence time.
  • the sampling system included a filter to remove particulate and a chiller to condense out water.
  • NO and NO 2 are measured using a Thermo Environmental Instruments Model 42C High Level Chemiluminescence Analyzer.
  • SO 2 is analyzed using a Western Bovar 721 AT2 analyzer.
  • This analyzer has a range of 0-1000 ppm SO 2 which is lower than the level produced in the furnace. Therefore the sample is diluted 3:1 with nitrogen and the measured S0 2 signal is corrected to give the proper value.
  • PM10 particulate measurements are conducted with the TSI Model 8520 DusTrak Aerosol Monitor. This instrument uses laser scattering to measure the number of particulates smaller than a specific size.
  • a preferred co-fire ratio of 20%, by the heat input, of oxygenate resulted in a 63.4% reduction in NOx and a 95.1% reduction in PM10.
  • Oxygenate Co-fired NO x SO 2 (by % heat Emissions NO x Emissions SO 2 input) Lb/MM BTU % Reduction Lb./MM BTU % Reduction 0% 0.631 0.0% 5.28 0.0% 2.5% 0.567 10.1% 5.00 5.3% 5% 0.550 12.9% 4.88 7.4% 10% 0.414 34.4% 4.75 10.0% 15% 0.358 43.3% 4.50 14.7% 20% 0.231 63.4% 3.74 29.1% 30% 0.197 68.7% 3.50 33.7% 40% 0.190 69.8% 2.99 43.3% Oxygenate Co-Fired PM10 (by % heat Emissions PM 10 input) Microgm/m3 % Reduction 0% 75619 0.0% 2.5% 74918 0.9% 5% 76825 ⁇ 1.6% 10% 54449 28% 15% 16298 78.4% 20% 3708 95.1% 30% 32682 56.8% 40% 41622 45.0%
  • Oxygenate Co-fired NO x SO 2 (by % heat Emissions NO x Emissions SO 2 input) Lb/MM BTU % Reduction Lb./MM BTU % Reduction 0% 0.452 0.0 6.10 0.0 2.5% 0.385 14.7 5.65 7.4 5% 0.364 19.3 5.47 10.3 10% 0.349 22.8 5.50 9.7 15% 0.344 23.7 5.32 12.7 20% 0.292 35.3 5.19 14.9 30% 0.312 30.9 4.26 30.1 40% 0.207 54.1 3.70 39.2 50% 0.175 61.2 3.12 48.9 Oxygenate Co-Fired PM10 (by % heat Emissions PM 10 input) Microgm/m3 % Reduction 0% 37217 0.0 2.5% 43451 ⁇ 16.8 5% 17068 54.1 10% 22734 38.9 15% 17509 53.0 20% 11279 69.7 30% 11004 70.4 40% 5021 86.5 50% 3014 91.9

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Combustion Of Fluid Fuel (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Methods of reducing the NOx emissions generated from the burning of pulverized coal in a heat-producing unit, wherein the method comprises the steps of: (a) introducing pulverized coal into a combustion chamber of the heat-producing unit; and (b) co-firing the pulverized coal with an oxygenate source selected from glycerol, glycerol derivatives, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, fatty acid alkyl esters, fatty alcohols, and mixtures thereof, where the combustion of the oxygenate source generates at least 2.5%, on a heat input basis, of the total heat generated by the co-firing.

Description

    CROSS REFERENCE TO RELATED APPLICATIONS
  • This application is a divisional of U.S. application Ser. No. 10/612,354, filed Jul. 2, 2003.
  • FIELD OF INVENTION
  • The present invention relates to a method of combusting coal for the generation of heat and power that results in reduced emission of oxides of nitrogen (NOx) which consists of a co-firing pulverized coal, preferably in a boiler or furnace system, with an effective amount of an oxygen-containing organic compound.
  • BACKGROUND OF THE INVENTION
  • The demands of an industrialized society and the consequent need to burn fuel for the generation of energy tend to compromise air quality. Existing fuels that are burned in boiler systems and furnaces to produce heat and power include distillate fuel oil, residual (number 6) fuel oil, blends of distillate and residual fuel oil, and coal. Many of the existing energy sources, particularly fossil fuels such as petroleum and coal, release substantial amounts of pollutants, such as nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO) and particulate matter (PM) upon combustion. These pollutants cause respiratory diseases and other human ailments. These pollutants also poison the environment via acid rain, ground level ozone and greenhouse gases.
  • Being the least expensive and available in relative abundance, coal is the preferred fuel in many instances. Unfortunately however, the combustion of coal generates substantial quantities of harmful pollutants, such as sulfur dioxide, oxides of nitrogen, carbon monoxide and particulates. Fuels other than coal often have fewer effects on air quality, but tend to be more expensive, or be in relatively short supply.
  • Environmental legislation, such as the Clean Air Act in the United States, has been enacted in many countries to control the amount of various chemicals released into the atmosphere in an effort to protect human health and the environment. At a local or regional level, industry is typically regulated by state or regional environmental protection agencies that set limits as to the amounts of airborne pollutants that can be emitted from a given source.
  • As energy demands increase, the pressures, conflicts and costs involved in supplying that energy without exacerbating these health and environmental problems become increasingly difficult.
  • In recent years, much work has been conducted on finding ways of reducing the output of NOx and SOx and other pollutants from coal combustion. The most common means of reducing NOx emissions is the use of Selective Catalytic Reduction (SCR) technology. However, this approach requires the construction of an expensive catalytic system to treat the exhaust gases from the combustion process. This approach may not be cost effective for smaller coal fired furnaces or boilers.
  • Another approach is to use staged combustion to reduce NOx wherein there are more than one individualized combustion zones in the furnace. While this technique is suitable for the construction of a new furnace, it is not easily or inexpensively retrofitted to existing furnaces.
  • Yet another approach is the use of additives during the combustion process to effect changes in the combustion conditions such that emissions are reduced. In one method, calcium compounds such as CaO, CaCO3, CaF, etc, are added to the combustion zone to effect the reduction in NOx and SOx emissions. However, this and similar techniques result in a slag disposal issue.
  • Another method of reducing NOx emissions (at the point of exit from the stack) is to combine another fuel having less NOx emissions per heating unit value, such as fuel oil, in a furnace or boiler, with the coal. Such combination can reduce the overall NOx emissions while providing the same or similar overall heating values. Although this method often permits coal-burning facilities to meet air quality regulations, it is simply a substitution of a more expensive, but less NOx emitting fuel for the coal. The fuel oil does not actually reduce the emissions of the coal itself, but rather, reduces the emissions from the heating system itself.
  • In short, notwithstanding previous attempts to solve the emissions problems associated with the combustion of fossil fuels, especially coal, there is a continuing need to develop coal burning methods that improve the NOx emissions, can be cost-effectively retrofitted to existing heat-producing units, such as furnaces and boilers.
  • SUMMARY OF THE INVENTION
  • It has now surprisingly been discovered that the combination of pulverized coal and an effective amount of oxygenate, when burned as fuel to produce heat, will provide greater-than substitution effect reductions of emissions of NOx from the heat-generating unit.
  • Therefore the present invention relates to fuel compositions providing reduced emissions of NOx when combusted, wherein the composition comprises:
  • a) pulverized coal; and
  • b) an oxygenate selected from the group consisting of, glycerol, glycerol derivatives, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, fatty acid alkyl esters, fatty alcohols, and mixtures thereof.
  • The present invention also relates to methods of reducing the NOx emissions generated from the burning of pulverized coal in a heat-producing unit, wherein said method comprises the steps of:
  • a) introducing pulverized coal into a combustion chamber of the heat-producing unit; and
      • b) co-firing the pulverized coal with an oxygenate source selected from the group consisting of glycerol, glycerol derivatives, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, fatty acid alkyl esters, fatty alcohols, and mixtures thereof;
        wherein combustion of the oxygenate source generates at least 2.5%, on a heat input basis, of the total heat generated by the co-firing.
    DETAILED DESCRIPTION OF THE INVENTION
  • While the specification concludes with the claims particularly pointing and distinctly claiming the invention, it is believed that the present invention will be better understood from the following description.
  • All percentages and ratios used herein are by weight of the total composition and all measurements made are at 25° C., unless otherwise designated.
  • All cited references are incorporated herein by reference in their entirety.
  • The compositions and methods of the present invention can include, consist essentially of, or consist of, the components of the present invention as well as other ingredients described herein. As used herein, “consisting essentially of” means that the composition or component may include additional ingredients, but only if the additional ingredients do not materially alter the basic and novel characteristics of the claimed compositions or methods.
  • All percentages, parts and ratios are based upon the total weight of the compositions of the present invention, unless otherwise specified. All such weights as they pertain to listed ingredients are based on the active level and, therefore, do not include carriers or by-products that may be included in commercially available materials, unless otherwise specified.
  • It has now been found that the co-firing, in a combustion zone, of pulverized coal with a selected oxygenate source is useful for reducing the NOx emissions normally associated with coal burning.
  • Without being limited by theory, it is believed that the oxygenate synergistically reacts with the fired coal, resulting in a reduction in the NOx emissions attributed to the nitrogen found in the coal structure. Fuel-bound nitrogen is the source of approximately 80% of the NOx emissions from uncontrolled combustion of pulverized coal. Without being limited by theory, it is believed that the co-firing of the coal with oxygenate functions to reduce the conversion of fuel bound nitrogen to NOx. It is believed that the oxygenated fuel pyrolyzes faster than the coal, thereby consuming oxygen and creating a locally fuel rich zone around the firing source. In this fuel rich zone, it is speculated that nitrogen-containing molecules desorb from the coal and in the absence of excess oxygen, these nitrogen compounds are reduced to N2.
  • In accordance with the invention, reduced emissions of NOx and particulates are achieved when the pulverized coal is co-fired with a selected oxygenate source.
  • The NOx-reducing fuel compositions and methods herein may also include a wide variety of other ingredients/steps. The compositions and methods of the present invention are described in detail hereinafter.
  • A) Pulverized Coal
  • As used herein, “pulverized coal” refers to a lignite, anthracite and/or bituminous coal that is either already small enough or has been subjected to mechanical particle size reduction such that the resulting “pulverized” material can be conveyed via fluidization with air through a pipe into the combustion chamber of a furnace or boiler.
  • Preferably, the pulverized coal useful herein is at least 50% under 200 mesh (74 microns), more preferably the coal useful herein is at least 60% under 200 mesh, and even more preferably, at least 70% under 200 mesh.
  • B) Oxygenate Source
  • The fuel compositions of the present invention contain an oxygenate source. As used herein, “oxygenate source” refers to an organic compound consisting primarily of hydrogen, carbon and oxygen atoms. Oxygenate sources useful herein include glycerine and/or glycerol derivatives, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, methyl esters of natural fats and oils (biodiesel), fatty alcohols of natural fats and oils, and mixtures thereof.
  • The natural fats and oils themselves and/or the fatty acids derived from such fats and oils may be optionally added as a secondary oxygenate source to one or more of the oxygenated sources.
  • In accordance with the invention, reduced emissions of NOx are achieved when pulverized coal is co-fired in a combustion chamber of, for instance, a furnace or boiler, in conjunction with an effective amount of an oxygenate source. Preferably the oxygenate source material is co-fired with the pulverized coal such that the oxygenate source material accounts for from about 2.5% to about 40% on a heat input basis, of the heat output generated. More preferably, the oxygenate source material accounts for from about 10% to about 20%, on a heat input basis, of the heat output generated. Co-firing may occur by blending the oxygenate source with the coal prior to, during, and/or after pulverization, or may be injected into the combustion zone via a separate nozzle.
  • 1. Glycerine and/or Glycerol Derivatives
  • The oxygenate source of the present invention may be selected from glycerine and/or glycerol derivatives. As used herein, the terms “glycerine” or “glycerol” can be used interchangeably and refer to 1,2,3 hydroxypropane or 1,2,3, propanetriol. Glycerine is typically produced as a co-product from the production of soaps, fatty acids, fatty alcohols and alkyl esters. Glycerine from these sources is commonly referred to as “natural glycerine”. Another possible source of natural glycerine is from the hydrogenation or enzymatic conversion of glucose, sorbitol or other sugars to glycerine and other polyols. Yet another source of natural glycerine is to recover it from the waste products of ethanol fermentation. “Synthetic” glycerine is produced from propylene, typically through the allyl chloride to epichlorohydrin process as practiced by Dow Chemical. Glycerine from any source, or combination of sources may be used herein.
  • The glycerol derivatives preferred for use herein include ethers in which 1 to 3 of the glycerol hydroxyl groups have been etherified. A wide range of olefins may be used to etherify the glycerol. As used herein, “olefin” refers to an unsaturated straight, branched or cyclic hydrocarbon of C2-C10. Examples of olefins useful herein include ethylene, propylene, butylenes, isobutylene, pentene, cyclopentene, isopentene, hexane, cyclohexene, 3-methylpentene, 2,2-dimethylbutene, 2,3-dimethyl butene, 1-heptene, 2-heptene, 3-heptene, I-octene, 2-octene, 3-octene, 4-octene, 1-nonene, 2-nonene, 3-nonene, 4-nonene, 1-decene, 2-decene, 3-decene, 4-decene, 5-decene and the like. C2-C6 olefins are preferred due to their low cost. Mixtures of olefins can be employed, for example if the glycerol were reacted with a mixture of olefins in unpurified form.
  • A method for etherifying glycerol may be found in U.S. Pat. No. 5,476,971.
  • Another glycerol derivative that is useful herein is the reaction product of glycerol and acetone having the formula 2,2-dimethyl-1,3-dioxolane-4-methanol, commonly called solketal.
  • Preferably, the glycerol derivative of the present invention is selected from di t-butyl glycerol ethers, tri t-butyl glycerol ethers, solketal, or mixtures thereof. More preferably, the glycerol derivative is a mixture of di t-butyl and tri t-butyl glycerol ethers comprised roughly of 80% di t-butyl glycerol and 20% tri t-butyl glycerol.
  • Preparation of the Glycerol Ether
  • The process for making glycerol ethers is known to those of ordinary skill in the art. Typical catalysts include organic acid catalysts such as para-toluenesulfonic acid, acidic ion exchange resins such as Amberlyst 15 or the class of crystalline metallosilicates known as zeolite catalysts. Catalyst levels should range between 0.1 and 5 wt % of polyol. Typical reaction temperatures range from about 50° C. to about 200 ° C., preferably from about 50° C. to about 150° C., and more preferably from about 50° C. to about 100 ° C. Typical reaction pressures range from about 40 psig to about 1000 psig, preferably from about 40 psig to about 300 psig and more preferably from about 50 psig to about 150 psig. Typical olefin:polyol molar ratios range from about 1:1 to about 5:1, preferably from about 2:1 to about 3:1. Typical reaction times are from about 2 to about 24 hours, preferably from about 2 to about 10 hours, and more preferably from about 2 to about 6 hours. Reaction according to this synthesis process proceeds to about 95% polyol conversion. Separation of the mono-, di- and tri-ethers may be accomplished by appropriate steps, such as liquid-liquid extraction.
  • 2. Propylene Glycol and Derivatives
  • The oxygenate source of the present invention may be selected from propylene glycol or derivatives thereof. Propylene glycol derivatives useful herein include dipropylene glycol and polypropylene glycol having a molecular weight of from about 200 to about 1,000, e.g., polypropylene glycol 400. Other propylene glycol derivatives herein include: glycol ethers such as mono, di, tri propylene glycol butyl ether; mono, di, tripropylene glycol methyl ether; mono, di, tripropylene glycol tertiary butyl ether; mono, di, tripropylene glycol ethyl ether; mono, di tripropylene glycol propyl ether; mono, di, tripropylene glycol pentyl ether; mono, di, tripropylene glycol hexyl ether; and mono, di tripropylene glycol propionate.
  • 3. Ethylene Glycol Derivatives
  • The oxygenate source of the present invention may be selected from ethylene glycol and derivatives thereof. Ethylene glycol derivatives useful herein include diethylene glycol and polyethylene glycol having a molecular weight of from about 200 to about 1,000, e.g., polyethylene glycol 400. Other ethylene glycol derivatives herein include: glycol ethers such as ethylene glycol monobutyl ether (butyl cellosolve); diethylene glycol monobutyl ether (butyl carbitol); triethylene glycol monobutyl ether; tetraethylene glycol monobutyl ether; ethylene glycol hexyl ether; diethylene glycol hexyl ether; ethylene glycol ethyl ether; ethylene glycol methyl ether; ethylene glycol propyl ether; ethylene glycol pentyl ether; diethylene glycol methyl ether; diethylene glycol ethyl ether; diethylene glycol propyl ether; diethylene glycol pentyl ether; triethylene glycol methyl ether; triethylene glycol methyl ether; triethylene glycol propyl ether; triethylene glycol pentyl ether; triethylene glycol hexyl ether; and ethylene glycol acetate.
  • 4. Fatty Acid Alkyl Esters (Biodiesel)
  • The oxygenate source of the present invention may be selected from fatty acid alkyl esters, also commonly referred to as “biodiesel” fuels. The term “alkyl” herein refers to a saturated straight, branched or cyclic hydrocarbon of C1-C10, and includes methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, cyclopentyl, isopentyl, neopentyl, hexyl, hextyl, octyl, nonyl, decyl and combinations thereof.
  • A wide range of oils and fats derived from animals and plants may be used as the source of such fatty acid alkyl esters. Examples of oils and fats useful herein include beef tallow, coconut oil, corn oil, cottonseed oil, lard, olive oil, palm oil, palm kernel oil, peanut oil, soybean oil, linseed oil, tung oil, sunflower oil, safflower oil, canola oil, rapeseed oil, sesame oil, babassu oil, perilla oil, oiticica oil, fish oils, menhaden oil, castor oil, chinese tallow tree oil, physic nut oil, cuphea seed oil, microalgal oils, bacterial oils and fungal oils. While a wide range of oils, or mixture of oils, can be used as the source of fatty acid alkyl esters in the present invention, it is particularly applicable to soybean oil, canola oil, rapeseed oil, sunflower oil and recycled (waste) cooking oil or grease.
  • Preferably, the fatty acid alkyl esters used herein are selected from the methyl esters of soybean oil, yellow grease, rapeseed oil, and mixtures thereof.
  • 5. Fatty Alcohols
  • The oxygenate source of the present invention may be selected from fatty alcohols of oils and/or fats. A wide range of oils and fats derived from animals and plants may be used as the source of such fatty alcohols. Examples of oils and fats useful herein include beef tallow, coconut oil, corn oil, cottonseed oil, lard, olive oil, palm oil, palm kernel oil, peanut oil, soybean oil, linseed oil, tung oil, sunflower oil, safflower oil, canola oil, rapeseed oil, sesame oil, babassu oil, perilla oil, oiticica oil, fish oils, menhaden oil, castor oil, chinese tallow tree oil, physic nut oil, cuphea seed oil, microalgal oils, bacterial oils and fungal oils. While a wide range of oils, or mixture of oils, can be used as the source of fatty alcohols in the present invention, it is particularly applicable to coconut, palm kernel, palm, tallow, and mixtures thereof.
  • Optional Secondary Oxygenates
  • In addition to the oxygenates useful herein, other oil or oil-based additives that contain oxygen, such as fatty-acid still bottoms, may be included in the co-firing herein as secondary oxygenates. Such materials may further reduce NOx emissions.
  • A wide range of oils and fats derived from animals and plants may be used. Examples of oils and fats useful herein include beef tallow, coconut oil, corn oil, cottonseed oil, lard, olive oil, palm oil, palm kernel oil, peanut oil, soybean oil, linseed oil, tung oil, sunflower oil, safflower oil, canola oil, rapeseed oil, sesame oil, babassu oil, perilla oil, oiticica oil, fish oils, menhaden oil, castor oil, chinese tallow tree oil, physic nut oil, cuphea seed oil, microalgal oils, bacterial oils and fungal oils. Fatty acids derived from any of these oils and/or fats or combinations thereof may be useful herein as secondary oxygenates. While a wide range of oils, or mixture of oils, can be used as the source of fatty acids in the present invention, it is particularly applicable to soybean oil, tallow, recycled (waste) cooking oil or grease.
  • C) Heat-Producing Unit
  • As used herein, “heat-producing unit” refers to a combustion unit in which coal is burned to generate heat energy. The heat energy generated may then be used to heat water or produce steam, such as in a boiler or furnace. Suitable heat producing units include furnaces and boilers wherein pulverized coal is burned. This heat can be used to produce steam for driving electricity-producing turbines or to supply heat to operate a manufacturing process or to provide heat for buildings and structures.
  • The boilers useful in the methods of the present invention will preferably include at least one of the following and may include, for example, an air supply system, water supply and cooling system, a combustion chamber, fuel supply systems, a flue-gas cooling chamber, scrubber, an air induced-draft fan, a stack, or combinations of any two or more of these features.
  • Preferably, the burner is a low NOx burner wherein the system is already optimized for the lowest NOx emissions possible for use with pulverized coal fuel.
  • In order to have combustion, there must be one air source available to the burner which is commonly referred to as the “primary air flow.” Preferably, there is at least one additional air flow injected downstream of the burner air. Such additional air flow may be a secondary and/or tertiary air flow. These additional air flows may include overfire air, underfire air, curtain air, or mixtures thereof. In a preferred burner/air arrangement, primary air comes into the burner with the coal, secondary and tertiary air follows. Preferably, there is an overfire air downstream that is located a distance away from the burner that is 65% of the distance to the flue gas sampling port. The Stoichiometric Ratio is the actual air/theoretical air for complete combustion of the coal.
  • In preferred heat-producing units, the burner air is distributed as follows:
  • Primary, 24% Stoichiometric Ratio (SR)=0.2
  • Secondary, 25% SR=0.22
  • Tertiary, 51% SR=0.43
  • Total air at burner is SR=0.85
  • The stoichiometric ratio is preferably at least about 0.8 in order to reduce corrosion and/or deposits of undesirable by-products.
  • D) Co-Firing
  • The methods of the present invention include co-firing of pulverized coal with an oxygenate source in a heat-producing unit. As used herein, “co-firing” refers to a process or method by which a secondary fuel (here an oxygenate source) is injected into the combustion chamber of a heat-producing unit at the same and/or similar times as a primary (here, pulverized coal) fuel in order to burn at least somewhat concurrently. The two fuels are preferably introduced into the combustion chamber,through a separate injection device or system.
  • Pollutant-emission levels can be maintained at or below regulated limits by evaluating the respective pollutant-emission concentrations produced by the oxygenate and by the coal. The energy producer can then calculate the concentration ratio of the oxygenate and the fuel(s) that will produce a desired emission concentration (e.g., an emission concentration within the regulated limit) for the NOx (or other pollutant) then burn at least that much oxygenate in combination with the pulverized coal. The necessary concentration of the oxygenate may be calculated based on its percentage heat input as a function of the overall (fixed) heat input of the combined fuels. As used herein, the term “co-firing ratio” refers to the percentage of total heat generated from the combustion of the oxygenate source. Preferably, the co-firing ratio of oxygenate source to coal is from about 2.5% to about 50%, preferably from about 10% to about 30%.
  • In preferred heat-producing units or systems the oxygenate source is in liquid form and is fed through a dual fluid nozzle that atomizes the premixed fuel/air. The liquid port is separated from the coal port, but injected substantially simultaneously.
  • Optional Method Steps/Modifications
  • The methods of the present invention do not require additional equipment modifications or after treatment devices such as air-staging, scrubbers, Selective Non-Catalytic Reduction units, or Selective Catalytic Reduction units in order to benefit from the NOx emissions reductions. However, such equipment modifications or after-treatment devices may be incorporated into the methods of the present invention if so desired, to further reduce NOx emissions.
  • 1) Air Staging
  • The methods of the present invention may optionally include air staging. As used herein, “air staging” refers to the known method of introducing combustion air in “stages” along the combustion zone as opposed to all the air being introduced at the point coal enters the furnace. Several patents describe staged combustion techniques that may further reduce nitrogen oxide emissions from the combustion of fuels containing nitrogen. For example, See, U.S. Pat. No. 3,727,562; U.S. Pat. No. 4,343,606; and references cited therein.
  • 2) Selective Catalytic Reduction Units
  • Selective Catalytic Reduction Units are a post-combustion NOx-controlling technology that are theoretically capable of providing NOx reductions in excess of 90% (realistically greater than 50% as of today). NOx reductions are achieved by injecting ammonia and/or urea into the flue gas, which then passes through layers of catalyst in a reactor. The ammonia and/or urea react with the NOx on the surface of the catalyst, forming molecular nitrogen and water.
  • Preferably, the methods of the present invention include a further step of treating the flue gas with an optional modification selected from air staging, selective non-catalytic reduction units, selective catalytic reductions, scrubbers, and combinations thereof. However, any known modification or methodology associated with heat-producing units may be added to the methods of the present invention.
  • EXAMPLES
  • To demonstrate an embodiment of this invention, the following system is used:
  • Combustion system—A pulverized coal combustion test furnace, referred to as the “L1500”, is a nominal 5 MM BTU/hr (1.5 MW) furnace designed to simulate commercial combustion conditions. The inner dimensions of the horizontal-fired combustor are 42×42 inches square and 40 feet long. The walls have multiple layered insulation to reduce the temperature from about 3000° F. on the fire-side to below 140° F. on the shell side. The combustor is modular in design, and is made up of 12 sections with numerous access ports and optional cooling panels in each section. This allows the flue gas temperature profile to be adjusted to better simulate commercial equipment. The access ports are used for visual observations, fuel and or air injection, and product sampling.
  • The overall combustion facility includes the air supply system, water supply system and cooling system, L1500 combustor, fuel supply systems, a flue-gas cooling chamber, scrubber, and induced-draft fan and a stack.
  • The burner in the L1500 is a low NOx design, having primary, secondary and tertiary air inputs that can be independently controlled in terms of flow rate, preheat temperature and, for the secondary and tertiary air registers, degree of swirl. Overfire air is injected downstream in the furnace.
  • Coal is injected into the furnace through the center of the burner. The coal injector consists of a 1.5 inch pipe inside a 3-inch pipe. Coal is fed through the annulus between the two pipes; the 1.5-inch pipe acts as a bluff body.
  • For the tests set out herein, the burner system is modified to allow injection of liquid fuel. A dual-fluid (oil+air) atomizing nozzle is inserted through the 1.5-inch bluff body pipe in the center of the burner so that the tip of the nozzle is set back approximately one inch from the end of the 1.5-inch pipe. Liquid fuel and air are premixed and fed through six small holes in the injector tip. By this design the liquid is well atomized and fed directly into the center of the coal stream.
  • The liquid fuel is fed from two 10-gallon pressure tanks connected in parallel, Compressed air is applied to the tanks, which forced the liquid out from the tanks, through a digital flow meter and into the burner. Adjusting the air pressure could vary the liquid flow rate.
  • Analysis System—Samples can be taken from any two locations in the furnace. For the data herein, they are pulled from Section 6 which corresponds to approximately a two second residence time and is representative of an industrial pulverized coal boiler. Samples are also taken at the furnace outlet, corresponding to about 5 seconds residence time. The sampling system included a filter to remove particulate and a chiller to condense out water.
  • NO and NO2 are measured using a Thermo Environmental Instruments Model 42C High Level Chemiluminescence Analyzer.
  • SO2 is analyzed using a Western Bovar 721 AT2 analyzer. This analyzer has a range of 0-1000 ppm SO2 which is lower than the level produced in the furnace. Therefore the sample is diluted 3:1 with nitrogen and the measured S02 signal is corrected to give the proper value.
  • PM10 particulate measurements are conducted with the TSI Model 8520 DusTrak Aerosol Monitor. This instrument uses laser scattering to measure the number of particulates smaller than a specific size.
  • Based upon the use of the combustion system and the analysis system set out above, the following Examples illustrate practice of the invention but without limiting its scope:
  • As may be seen from the Example tables below, if dilution of the coal NOx emissions by the addition of oxygenates is the only mechanism in operation, the emissions would be expected to decrease linearly with an increasing co-fire ratio. Such a relationship is illustrated by the rates of SO2 emissions. Since the oxygenates contain no sulfur, the SO2 emissions data shows the direct linear response in SO2 emitted as the sulfur containing coal is substituted by sulfur-free oxygenate. However, the NOx and PM10 rates indicate a very different and novel response. As the co-fire ratio of oxygenates is increased, there are unexpectedly disproportionately larger decreases in NOx and PM10 emissions.
  • A preferred co-fire ratio of 20%, by the heat input, of oxygenate resulted in a 63.4% reduction in NOx and a 95.1% reduction in PM10.
  • Example 1
  • Coal with Oxygenate
    Primary fuel: Illinois #5 coal
    Oxygenate: Mixture of 80% di t-butyl and 20% tri t-butyl
    glycerol ethers
    Total heat input: 4 million BTU/hr
    Burner conditions:
    Primary air 24% of burner air, SR = 0.20
    Secondary air 25% of burner air, SR = 0.22
    Tertiary air 51% of burner air, SR = 0.43
    Total air input SR = 0.85
    Overfire air: SR = 0.30
    Total air: SR = 1.15
    Co-firing ratios (heat %) 2.5, 5, 10, 15, 20, 30, 40
  • Example 1 Resulting Emissions
  • Oxygenate
    Co-fired NOx SO2
    (by % heat Emissions NOx Emissions SO2
    input) Lb/MM BTU % Reduction Lb./MM BTU % Reduction
     0% 0.631 0.0% 5.28 0.0%
    2.5%  0.567 10.1% 5.00 5.3%
     5% 0.550 12.9% 4.88 7.4%
    10% 0.414 34.4% 4.75 10.0%
    15% 0.358 43.3% 4.50 14.7%
    20% 0.231 63.4% 3.74 29.1%
    30% 0.197 68.7% 3.50 33.7%
    40% 0.190 69.8% 2.99 43.3%
    Oxygenate
    Co-Fired PM10
    (by % heat Emissions PM 10
    input) Microgm/m3 % Reduction
     0% 75619  0.0%
    2.5%  74918  0.9%
     5% 76825  −1.6%
    10% 54449   28%
    15% 16298 78.4%
    20% 3708 95.1%
    30% 32682 56.8%
    40% 41622 45.0%
  • Example 2
  • Oxygenate and Coal
    Primary fuel: Illinois #5 coal
    Oxygenate: Soybean Methyl Ester
    Total heat input: 4 million BTU/hr
    Burner conditions:
    Primary air 24% of burner air, SR = 0.20
    Secondary air 25% of burner air, SR = 0.22
    Tertiary air 51% of burner air, SR = 0.43
    Total air input SR = 0.85
    Overfire air: SR = 0.30
    Total air: SR = 1.15
    Co-firing ratios (heat %) 2.5, 5, 10, 15, 20, 30, 40, 50
  • Example 2 Resulting Emissions
  • Oxygenate
    Co-fired NOx SO2
    (by % heat Emissions NOx Emissions SO2
    input) Lb/MM BTU % Reduction Lb./MM BTU % Reduction
     0% 0.452 0.0 6.10 0.0
    2.5%  0.385 14.7 5.65 7.4
     5% 0.364 19.3 5.47 10.3
    10% 0.349 22.8 5.50 9.7
    15% 0.344 23.7 5.32 12.7
    20% 0.292 35.3 5.19 14.9
    30% 0.312 30.9 4.26 30.1
    40% 0.207 54.1 3.70 39.2
    50% 0.175 61.2 3.12 48.9
    Oxygenate
    Co-Fired PM10
    (by % heat Emissions PM 10
    input) Microgm/m3 % Reduction
     0% 37217 0.0
    2.5%  43451 −16.8
     5% 17068 54.1
    10% 22734 38.9
    15% 17509 53.0
    20% 11279 69.7
    30% 11004 70.4
    40% 5021 86.5
    50% 3014 91.9
  • While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims (14)

1. A method of reducing the NOx emissions generated from the burning of pulverized coal in a heat-producing unit, wherein said method comprises the steps of:
a) introducing pulverized coal into a combustion chamber of the heat-producing unit; and
b) co-firing the pulverized coal with an oxygenate source selected from the group consisting of glycerol, propylene glycol, propylene glycol derivatives, ethylene glycol, ethylene glycol derivatives, fatty acid alkyl esters, fatty alcohols, and mixtures thereof;
wherein combustion of the oxygenate source generates at least 2.5%, on a heat input basis, of the total heat generated by the co-firing.
2. A method according to claim 2 wherein the oxygenate source is selected from the group consisting of glycerol derivatives, propylene glycol derivatives, ethylene glycol derivatives, fatty acid alkyl esters, and mixtures thereof.
3. A method according to claim 2 wherein the glycerol derivative is selected from the group consisting of glycerol ethers in which 1 to 3 of the glycerol hydroxyl groups have been etherified.
4. A method according to claim 2 wherein the glycerol derivative is selected from the group consisting of di t-butyl glycerol ethers, tri t-butyl glycerol ethers, solketal, and mixtures thereof.
5. A method according to claim 1 wherein the oxygenate is selected from the group consisting of methyl esters of fatty acids, and mixtures thereof.
6. A method according to claim 1 wherein the heat-producing unit is a coal-burning boiler.
7. A method according to claim 1 wherein the heat-producing unit is a coal-burning furnace.
8. A method according to claim 1 wherein the pulverized coal and the oxygenate source are introduced into the combustion chamber through separate injection devices.
9. A method according to claim 1 wherein the pulverized coal and the oxygenate source are burned substantially concurrently.
10. A method according to claim 6 wherein the boiler comprises an air supply system, a flue-gas cooling chamber, and a stack.
11. A method according to 6 wherein the boiler comprises a low-NOx burner co-located with the combustion chamber and further comprises air fired downstream of burner air selected from the group consisting of secondary air flows, tertiary air flows, and mixtures thereof.
12. A method according to claim 1 wherein combustion of the oxygenate source generates from about 2.5% to about 40%, on a heat input basis, of the total heat generated by the co-firing.
13. A method according to claim 12 wherein the oxygenate source is a mixture of di t-butyl and tri t-butyl glycerol ethers.
14. A method according to claim 1 wherein the composition further comprises a secondary oxygenate source selected from the group consisting of oils, fats, fatty acids, and mixtures thereof.
US11/657,305 2003-07-02 2007-01-24 Method for combustion of pulverized coal with reduced emissions Abandoned US20070113468A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US11/657,305 US20070113468A1 (en) 2003-07-02 2007-01-24 Method for combustion of pulverized coal with reduced emissions

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10/612,354 US7195656B2 (en) 2003-07-02 2003-07-02 Method for combustion of pulverized coal with reduced emissions
US11/657,305 US20070113468A1 (en) 2003-07-02 2007-01-24 Method for combustion of pulverized coal with reduced emissions

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US10/612,354 Division US7195656B2 (en) 2003-07-02 2003-07-02 Method for combustion of pulverized coal with reduced emissions

Publications (1)

Publication Number Publication Date
US20070113468A1 true US20070113468A1 (en) 2007-05-24

Family

ID=33552495

Family Applications (3)

Application Number Title Priority Date Filing Date
US10/612,354 Expired - Lifetime US7195656B2 (en) 2003-07-02 2003-07-02 Method for combustion of pulverized coal with reduced emissions
US11/657,146 Abandoned US20070130823A1 (en) 2003-07-02 2007-01-24 Method for combustion of pulverized coal with reduced emissions
US11/657,305 Abandoned US20070113468A1 (en) 2003-07-02 2007-01-24 Method for combustion of pulverized coal with reduced emissions

Family Applications Before (2)

Application Number Title Priority Date Filing Date
US10/612,354 Expired - Lifetime US7195656B2 (en) 2003-07-02 2003-07-02 Method for combustion of pulverized coal with reduced emissions
US11/657,146 Abandoned US20070130823A1 (en) 2003-07-02 2007-01-24 Method for combustion of pulverized coal with reduced emissions

Country Status (6)

Country Link
US (3) US7195656B2 (en)
EP (1) EP1641901A1 (en)
JP (1) JP2007531797A (en)
CN (1) CN1816610B (en)
BR (1) BRPI0412230A (en)
WO (1) WO2005003264A1 (en)

Families Citing this family (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7195656B2 (en) * 2003-07-02 2007-03-27 Procter & Gamble Company Method for combustion of pulverized coal with reduced emissions
US20080115409A1 (en) * 2006-11-17 2008-05-22 Tran Bo L Alternative fuel comprising combustible solids and by-products or waste material from industrial processes
US20080005956A1 (en) * 2004-05-14 2008-01-10 Tran Bo L Methods and compositions for controlling bulk density of coking coal
CN101083953B (en) 2004-12-21 2010-08-04 皇家飞利浦电子股份有限公司 Electric toothpaste
CA2670035C (en) * 2005-11-17 2018-06-12 Cps Biofuels, Inc. Glycerol ether fuel additive composition
EP1918354A1 (en) * 2006-10-13 2008-05-07 Cognis Oleochemicals GmbH Fuel compositions comprising glycerin
US20090025276A1 (en) * 2006-11-17 2009-01-29 Tran Bo L Alternative fuel comprising solids and by_products or waste material from industrial processes
EP1950273A1 (en) * 2007-01-18 2008-07-30 RWE Power Aktiengesellschaft Use of glycerol, glycerol-ethanol or glycerol-methanol blends as a fuel for furnaces
WO2008149352A2 (en) * 2007-06-04 2008-12-11 Pixer Technology Ltd. Apparatus and method for inducing controllable jets in liquids
ITMI20072209A1 (en) * 2007-11-21 2009-05-22 Eni Spa IMPROVED PROCEDURE FOR THE PRODUCTION OF SYNTHESIS GAS STARTING FROM OXYGENATED HYDROCARBONS OBTAINED FROM BIOMASSES
SE532840C2 (en) * 2008-02-14 2010-04-20 Lars Eriksson biofuel
CN101275095B (en) * 2008-04-29 2011-09-14 许学龙 Coal burning additive
WO2010006402A1 (en) * 2008-07-16 2010-01-21 Her Majesty The Queen In Right Of Canada As Represented By The Minister Of Natural Resources Canada Conversion of glycerol to naphtha-range oxygenates
DE102009055928A1 (en) * 2009-11-27 2011-06-01 Technische Universität Dortmund Process for the continuous production of glycerine tertiary butyl ethers
US20130145974A1 (en) * 2010-06-01 2013-06-13 Robert E. Brandt COMPOSITION AND METHOD FOR REDUCING SOx and NOx EMISSIONS FROM COMBUSTION OF FUEL
TR201103103A2 (en) * 2011-03-31 2012-05-21 Karaca Davut Calorie-enriched coal and its production method
US9011733B2 (en) 2011-12-21 2015-04-21 Joan Lynch Dielectric fluids compositions and methods
FR3000099A1 (en) * 2012-10-09 2014-06-27 Nicolas Valentic Chemical composition, useful for reducing sulfur oxides and nitrogen oxides formed during the combustion of fuels in boilers and engines that are used in cars and trucks, comprises an organic alkali metal salt and/or a silane or siloxane
EA201500867A1 (en) * 2013-02-22 2016-01-29 Рафаэль Леонардо Барроэта Валеро CATALYST FOR ASPHALT MIXTURE
GB2522612A (en) * 2013-12-16 2015-08-05 Al Hajam Establishment Volume Trading Fuel additive composition
CN107723053A (en) * 2017-10-31 2018-02-23 桂林市漓江机电制造有限公司 Combustion energy-saving combustion adjuvant and preparation method thereof
KR102079768B1 (en) * 2018-05-08 2020-02-20 에스케이가스 주식회사 A method for reducing nitrogen dioxide in the exhaust gas generated during an olefin production process
CN110129100B (en) * 2019-05-28 2023-12-22 彭万旺 Efficient combustion system and method
KR20230096602A (en) * 2021-12-23 2023-06-30 주식회사 케이티앤지 Combustible heat source for a smoking article and a smoking article comprising the same

Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US913713A (en) * 1907-11-08 1909-03-02 Alexander H Ege Artificial fuel.
US1447095A (en) * 1920-12-27 1923-02-27 Mcarthur William Burner
US3332755A (en) * 1964-06-03 1967-07-25 Apollo Chem Fuel additive
US4332593A (en) * 1980-01-22 1982-06-01 Gulf & Western Industries, Inc. Process for beneficiating coal
US4753661A (en) * 1986-01-21 1988-06-28 Polar Molecular Corporation Fuel conditioner
US5308365A (en) * 1993-08-31 1994-05-03 Arco Chemical Technology, L.P. Diesel fuel
US5425790A (en) * 1992-12-23 1995-06-20 Arco Chemical Technology, L.P. Diesel fuel
US5454842A (en) * 1994-12-02 1995-10-03 Exxon Research & Engineering Co. Cetane improver compositions comprising nitrated fatty acid derivatives
US5476971A (en) * 1995-01-13 1995-12-19 Arco Chemical Technology, L.P. Glycerine ditertiary butyl ether preparation
US5578090A (en) * 1995-06-07 1996-11-26 Bri Biodiesel fuel
US6174501B1 (en) * 1997-10-31 2001-01-16 The Board Of Regents Of The University Of Nebraska System and process for producing biodiesel fuel with reduced viscosity and a cloud point below thirty-two (32) degrees fahrenheit
US20030027014A1 (en) * 2000-06-26 2003-02-06 Ada Environmental Solutions, Llc Low sulfur coal additive for improved furnace operation
US20040168365A1 (en) * 2001-01-10 2004-09-02 Hundley Joseph W. Chemical change agent
US20050000150A1 (en) * 2003-07-02 2005-01-06 The Procter & Gamble Company Method for combustion of pulverized coal with reduced emissions

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1246853A (en) 1968-01-02 1971-09-22 Cities Service Oil Co Ethers as smoke suppressants
DE2129462C3 (en) 1971-06-14 1973-12-06 Chemische Fabrik Kalk Gmbh, 5000 Koeln Prevention of the self-ignition of carbon by calcium or magnesium chloride with the addition of a wetting agent
US4304636A (en) * 1980-02-19 1981-12-08 Apollo Technologies, Inc. Method for improving the bulk density and throughput characteristics of coking coal
CA1214039A (en) * 1982-09-30 1986-11-18 George E. Snow Process for the beneficiation of carbonaceous matter employing high shear conditioning
EP0649829B1 (en) 1993-10-15 1999-01-20 Fina Research S.A. Process for the production of glycerol ethers

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US913713A (en) * 1907-11-08 1909-03-02 Alexander H Ege Artificial fuel.
US1447095A (en) * 1920-12-27 1923-02-27 Mcarthur William Burner
US3332755A (en) * 1964-06-03 1967-07-25 Apollo Chem Fuel additive
US4332593A (en) * 1980-01-22 1982-06-01 Gulf & Western Industries, Inc. Process for beneficiating coal
US4753661A (en) * 1986-01-21 1988-06-28 Polar Molecular Corporation Fuel conditioner
US5425790A (en) * 1992-12-23 1995-06-20 Arco Chemical Technology, L.P. Diesel fuel
US5308365A (en) * 1993-08-31 1994-05-03 Arco Chemical Technology, L.P. Diesel fuel
US5454842A (en) * 1994-12-02 1995-10-03 Exxon Research & Engineering Co. Cetane improver compositions comprising nitrated fatty acid derivatives
US5476971A (en) * 1995-01-13 1995-12-19 Arco Chemical Technology, L.P. Glycerine ditertiary butyl ether preparation
US5578090A (en) * 1995-06-07 1996-11-26 Bri Biodiesel fuel
US6174501B1 (en) * 1997-10-31 2001-01-16 The Board Of Regents Of The University Of Nebraska System and process for producing biodiesel fuel with reduced viscosity and a cloud point below thirty-two (32) degrees fahrenheit
US20030027014A1 (en) * 2000-06-26 2003-02-06 Ada Environmental Solutions, Llc Low sulfur coal additive for improved furnace operation
US20040168365A1 (en) * 2001-01-10 2004-09-02 Hundley Joseph W. Chemical change agent
US20050000150A1 (en) * 2003-07-02 2005-01-06 The Procter & Gamble Company Method for combustion of pulverized coal with reduced emissions

Also Published As

Publication number Publication date
JP2007531797A (en) 2007-11-08
US20070130823A1 (en) 2007-06-14
CN1816610B (en) 2010-11-17
CN1816610A (en) 2006-08-09
US7195656B2 (en) 2007-03-27
EP1641901A1 (en) 2006-04-05
US20050000150A1 (en) 2005-01-06
WO2005003264A1 (en) 2005-01-13
BRPI0412230A (en) 2006-08-22

Similar Documents

Publication Publication Date Title
US20070113468A1 (en) Method for combustion of pulverized coal with reduced emissions
Yanik et al. NO and SO2 emissions from combustion of raw and torrefied biomasses and their blends with lignite
Whitty et al. Emissions from syngas combustion
ES2688361T3 (en) Mitigation of harmful combustion emissions using combustible raw materials containing sorbent
Dorokhov et al. Composition of a gas and ash mixture formed during the pyrolysis and combustion of coal-water slurries containing petrochemicals
ES2778907T3 (en) A process to cogasify and burn in conjunction with designer fuel coal
CA2457825C (en) Use of a natural-oil byproduct as a reduced-emissions energy source
Kouravand et al. Clean power production by simultaneous reduction of NOx and SOx contaminants using Mazut Nano-Emulsion and wet flue gas desulfurization
US20070034126A1 (en) In-Furnace Reduction Of Nitrogen Oxide By Mixed Fuels Involving A Biomass Derivative
El Sheikh et al. Advances in reduction of NOx and N2O1 emission formation in an oxy-fired fluidized bed boiler
Elkelawy et al. Biodiesel as an Alternative Fuel in Terms of Production, Emission, Combustion Characteristics for Industrial Burners: a Review
Kim et al. Effects of ammonia co-firing ratios and injection positions in the coal–ammonia co-firing process in a circulating fluidized bed combustion test rig
Xiaorui et al. NO emission characteristic during fluidized combustion of biomass with limestone addition
Gaba et al. Reduction of air pollution by combustion processes
Zaid et al. Coal fired power plant: a review on coal blending and emission issues
Chae et al. Characteristics of syngas reburning in a natural gas firing furnace-Effects of combustible gas species in the syngas
Hu et al. The effect of biomass pyrolysis gas reburning on N 2 O emission in a coal-fired fluidized bed boiler
Goughnour NOx reduction with the use of feedlot biomass as a reburn fuel
WO2015092386A1 (en) Fuel additive composition
DE19622299C2 (en) Method for operating a pressure-charged circulating fluidized bed furnace for generating a workable gas for the gas turbine of a combined cycle power plant
Lawrence Investigation of Synergistic NOx reduction from Cofiring and Air Staged Combustion of Coal and Low Ash Dairy Biomass in a 30 KiloWatt low NOx furnace
Oh Reburning renewable biomass for emissions control and ash deposition effects in power generation
Silver Investigation of Atomization and Combustion Performance of Renewable Biofuels and the Effects of Ethanol Blending in Biodiesel
Jancauskas et al. Combination of Primary Measures on Flue Gas Emissions in Grate-Firing Biofuel Boiler. Energies 2021, 14, 793
Arumugam Nitrogen oxides emission control through reburning with biomass in coal-fired power plants

Legal Events

Date Code Title Description
STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO PAY ISSUE FEE