CA2521183C - Process for burning sulfur-containing fuels - Google Patents
Process for burning sulfur-containing fuels Download PDFInfo
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- CA2521183C CA2521183C CA2521183A CA2521183A CA2521183C CA 2521183 C CA2521183 C CA 2521183C CA 2521183 A CA2521183 A CA 2521183A CA 2521183 A CA2521183 A CA 2521183A CA 2521183 C CA2521183 C CA 2521183C
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- oxidant
- sulfur
- combustion chamber
- fuel
- combustion
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- 239000000446 fuel Substances 0.000 title claims abstract description 97
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 83
- 239000011593 sulfur Substances 0.000 title claims abstract description 83
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims abstract description 69
- 230000008569 process Effects 0.000 title claims abstract description 65
- 238000002485 combustion reaction Methods 0.000 claims abstract description 119
- 239000007800 oxidant agent Substances 0.000 claims abstract description 97
- 230000001590 oxidative effect Effects 0.000 claims abstract description 97
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims abstract description 66
- 229910000027 potassium carbonate Inorganic materials 0.000 claims abstract description 40
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000003546 flue gas Substances 0.000 claims abstract description 21
- 229910052939 potassium sulfate Inorganic materials 0.000 claims abstract description 17
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims abstract description 16
- 235000011151 potassium sulphates Nutrition 0.000 claims abstract description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 50
- 239000001301 oxygen Substances 0.000 claims description 50
- 229910052760 oxygen Inorganic materials 0.000 claims description 50
- 235000011181 potassium carbonates Nutrition 0.000 description 27
- 239000003245 coal Substances 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 11
- 239000002245 particle Substances 0.000 description 11
- 230000007613 environmental effect Effects 0.000 description 8
- 239000002006 petroleum coke Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- 230000007246 mechanism Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000001603 reducing effect Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000004449 solid propellant Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- MJGPTHPXMVMHPS-UHFFFAOYSA-N 1,3,2-dioxathietan-4-one Chemical compound O=C1OSO1 MJGPTHPXMVMHPS-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000010763 heavy fuel oil Substances 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000005987 sulfurization reaction Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
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
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/508—Sulfur oxides by treating the gases with solids
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J7/00—Arrangement of devices for supplying chemicals to fire
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
- F23L7/007—Supplying oxygen or oxygen-enriched air
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/32—Direct CO2 mitigation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
Abstract
A process for burning a sulfur-containing fuel to produce a flue gas is disclosed. The process comprises introducing a sulfur-containing fuel into a combustion chamber, introducing an oxidant stream into the combustion chamber and mixing it with the sulfur-containing fuel to define a combustion zone, and introducing potassium carbonate into the combustion chamber. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate.
Description
PROCESS FOR BURNING SULFUR CONTAINING FUELS
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to the field of burning sulfur-containing fuels and to reducing the production of SOX and NO,, therein.
Related Art Over the past several years, power generation processes and other combustion processes for burning sulfur-containing fuels have been subject to increasingly strict emissions restrictions, particularly for NO,, and SOX. Sulfur-containing fuels that are popular for power generation but especially problematic for emissions include coal, petcoke and heavy fuel-oil boilers.
Current methods of removing SOX from, e.g., coal fired boilers are very expensive. It is anticipated that within a few years, most of those boilers in the U.S. will require de-sulfurization equipment. NOX removal techniques are similarly expensive, complex and difficult to operate. The preferred embodiments of the present invention disclose cost-effective methods to remove SOX and NOX.
Thus, a problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they produce a level of SOX emission that is unacceptable in view of existing environmental regulations.
Yet another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they produce a level of NOX emission that is unacceptable in view of existing environmental regulations.
Still another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been successively modified to provide adequate combustion characteristics resulting in adequate reduction of SOX formation sufficient to meet environmental guidelines without expensive and complex SOX treatment apparatus, such as scrubbers, etc.
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to the field of burning sulfur-containing fuels and to reducing the production of SOX and NO,, therein.
Related Art Over the past several years, power generation processes and other combustion processes for burning sulfur-containing fuels have been subject to increasingly strict emissions restrictions, particularly for NO,, and SOX. Sulfur-containing fuels that are popular for power generation but especially problematic for emissions include coal, petcoke and heavy fuel-oil boilers.
Current methods of removing SOX from, e.g., coal fired boilers are very expensive. It is anticipated that within a few years, most of those boilers in the U.S. will require de-sulfurization equipment. NOX removal techniques are similarly expensive, complex and difficult to operate. The preferred embodiments of the present invention disclose cost-effective methods to remove SOX and NOX.
Thus, a problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they produce a level of SOX emission that is unacceptable in view of existing environmental regulations.
Yet another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they produce a level of NOX emission that is unacceptable in view of existing environmental regulations.
Still another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been successively modified to provide adequate combustion characteristics resulting in adequate reduction of SOX formation sufficient to meet environmental guidelines without expensive and complex SOX treatment apparatus, such as scrubbers, etc.
Another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been successively modified to provide adequate combustion characteristics resulting in adequate reduction of NOX formation sufficient to meet environmental guidelines without expensive and complex NOX treatment apparatus.
An even further problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been provided with a means for chemically preventing the formation of SOX and concurrently provided with a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
Another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been provided with a means for chemically preventing the formation of NOX and concurrently provided with a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
For the foregoing reasons, there has been defined a long felt and unsolved need for a process for burning sulfur-containing fuels that facilitates an inexpensive, non-intrusive method for reducing the formation of SOX while at the same time maintaining the operability and safety of the combustion process.
A process for burning a sulfur-containing fuel to produce a flue gas is disclosed. The process comprises introducing a sulfur-containing fuel into a combustion chamber, introducing at least one oxygen enriched oxidant stream into the combustion chamber, and introducing potassium carbonate into the combustion chamber. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate.
An aspect of the present invention is to provide a process for burning sulfur-containing fuels that produces a level of SOX emission that is within acceptable levels in view of existing environmental regulations.
An even further problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been provided with a means for chemically preventing the formation of SOX and concurrently provided with a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
Another problem associated with processes for burning sulfur-containing fuels that precede the present invention is that they have not been provided with a means for chemically preventing the formation of NOX and concurrently provided with a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
For the foregoing reasons, there has been defined a long felt and unsolved need for a process for burning sulfur-containing fuels that facilitates an inexpensive, non-intrusive method for reducing the formation of SOX while at the same time maintaining the operability and safety of the combustion process.
A process for burning a sulfur-containing fuel to produce a flue gas is disclosed. The process comprises introducing a sulfur-containing fuel into a combustion chamber, introducing at least one oxygen enriched oxidant stream into the combustion chamber, and introducing potassium carbonate into the combustion chamber. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate.
An aspect of the present invention is to provide a process for burning sulfur-containing fuels that produces a level of SOX emission that is within acceptable levels in view of existing environmental regulations.
Yet another aspect of the present invention is to provide a process for burning sulfur-containing fuels that produces a level of NOX emission that is within acceptable levels in view of existing environmental regulations.
Still another aspect of the present invention is to provide a process for burning sulfur-containing fuels that can be successively modified to provide adequate combustion characteristics resulting in adequate reduction of SOX formation sufficient to meet environmental guidelines without expensive and complex SO, treatment apparatus, such as scrubbers, etc.
Another aspect of the present invention is to provide a process for burning sulfur-containing fuels that can be successively modified to provide adequate combustion characteristics resulting in adequate reduction of NOX formation sufficient to meet environmental guidelines without expensive and complex NOX treatment apparatus.
An even further aspect of the present invention is to provide a process for burning sulfur-containing fuels that provides a means for chemically preventing the formation of SO, and concurrently provides a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
Another aspect of the present invention is to provide a process for burning sulfur-containing fuels that provides a means for chemically preventing the formation of NOX, and concurrently provides a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
Another aspect of the present invention is to provide a process for burning a sulfur-containing fuel to produce a flue gas, the process comprising: introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet; oxygen-enriching at least one oxidant stream;
introducing a primary oxidant stream into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone;
introducing a secondary oxidant stream into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion 3a zone; introducing a tertiary oxidant stream into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zonethe tertiary oxidant stream completing combustion of the sulfur-containing fuel;
introducing potassium carbonate into the combustion chamber via the tertiary oxidant stream; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the oxidant entering the combustion chamber exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the primary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the secondary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the tertiary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the potassium carbonate is introduced into the combustion chamber in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%.
Another aspect of the present invention is to provide a process of the present invention wherein at least half' of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
Another aspect of the present invention is to provide a process of the present invention wherein the potassium carbonate is introduced into the combustion chamber through the fuel inlet.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the primary oxidant exceeds 21 %.
3b Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the secondary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the tertiary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process for burning a sulfur-containing fuel to produce a flue gas, the process comprising: introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet; introducing a primary oxidant stream containing more than 21 % oxygen into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone; introducing a secondary oxidant stream containing more than 21 % oxygen into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone; introducing a tertiary oxidant stream containing more than 21 %
oxygen into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zone; the total oxygen content of the oxidant entering the combustion chamber exceeding 21 %; introducing potassium carbonate into the combustion chamber through the tertiary air inlet in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate; wherein at least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
These and other aspects, advantages and features of the present invention will be apparent from the detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description that follows, reference will be made to the following figures:
Fig. 1 is a schematic illustration of a first preferred embodiment of a process for burning a sulfur-containing fuel;
WO 2004/087301 PCTlIB2004/000928 Fig. 2 is a schematic illustration of a second preferred embodiment of a process for burning a sulfur-containing fuel;
Fig. 3 is a schematic illustration of a third preferred embodiment of a process for burning a sulfur-containing fuel; and Fig. 4 is a graph illustrating data of theoretical data expected from burning a sulfur containing fuel according to a preferred embodiment of a process for burning sulfur-containing fuel.
DESCRIPTION OF PREFERRED EMBODIMENTS
In its simplest application, a process for burning a sulfur-containing fuel to produce a flue gas is disclosed. The process comprises introducing a sulfur-containing fuel into a combustion chamber, introducing an oxidant stream into the combustion chamber and mixing it with the sulfur-containing fuel to define a combustion zone, and introducing potassium carbonate into the combustion chamber. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate.
In the preferred embodiments, a combustion subassembly uses at least two, and sometimes three, oxidant streams. In the example in which coal is the sulfur-containing fuel, oxygen enrichment is employed to reduce NOR, as is more fully described in United States Patent Publication Number US 2004-0185404 Al.
In the preferred embodiments, a process designed to reduce SOX emissions in boilers, particularly in coal-fired boilers, is disclosed. The process includes introducing potassium carbonate in the combustion process, at the burner level or above the burners.
When used in conjunction with oxygen enrichment, NO,, reduction can be achieved, to an even greater degree than is expected by using oxygen enrichment alone. By this process, SOX
levels can be reduced to a few ppm, even for high-sulfur fuels such as Midwestern coals and pet coke.
At the same time, the NO,, reducing effect of the oxygen enrichment is enhanced by the potassium carbonate, resulting in a low NO. process. To avoid slagging effect of the high temperature on the potassium carbonate, a staged combustion process is most preferred.
Laboratory test data illustrates just a portion of the expected benefits in removing sulfur from pet-coke combustion using potassium carbonate. Test results show that the flue gas of both air-combustion (traditional) and oxy-combustion (oxygen enriched) contained approximately 6 ppm SO,,. This is extremely low in view of the fact that the pet-coke used contained approximately 3-6% sulfur. The reaction taking place in the combustion process is:
K2C03 + SO, -> K2S04 + C02. (1) Recent calculations made of the adsorption of SO2 by K2C03 in a pulverized coal boiler fired with Illinois No. 6 coal are illustrated as follows. It was assumed that one million pounds per hour of coal, corresponding to approximately 1000 MW power production, was to be burned with 10% excess air. An elemental composition of the parent coal reveals:
Element Wt% daf C 77.32 H 5,33 N 1.49 0 8.88 S 6.98 The coal was assumed to have 10% ash, and moisture was neglected. Note that the sulfur composition for this coal is high (approximately 7 wt.% daf). The adsorption rate was assumed to be limited by the diffusion of SO2 to the surface of the particle.
The mass transfer rate is:
N502 = h, (C5o2,g - Cs02,5) (2) where N 02 is the molar flux of SO2 to the particle surface per external surface area of particle, hm is the convective mass transfer coefficient, and CS02 is the concentration of gas in either the bulk gas phase or at the surface. Under diffusion-limited conditions, Cso2s is essentially zero, and equation (2) becomes very simple. The mass transfer coefficient is calculated from the Sherwood number, which is 2.0 for small particles:
Sh = hn,dn (3) DSO2-air where dp is the particle diameter, assumed to be 50 microns in this calculation. The diffusivity of SO2 was calculated from the Chapman-Enskog theory for kinetic gases. The parameters for air were used, since they are similar to post-combustion gases.
The diffusivity changes as a function of temperature.
For this calculation, a temperature profile was assumed. The particle and gas temperature started at 2000 K and then decreased in a linear fashion to 1000 K after one second. This is thought to approximate the conditions in most pulverized coal boilers.
The initial concentration of SO2 was calculated from the flow rates of coal and air, assuming that all of the sulfur in the coal ended up as SO2. This yielded a calculation of about 4510 ppm. The differential equation for the change in SO2 concentration in this case is:
dCs02 = n Ap NsOZ (3) dt where np is the particle number density (number of particles per cubic meter), Ap is the external area per particle (4 tr p2), and Ns02 is from equation (2).
The resulting SO2 profile is shown in Fig. 4. As shown, the calculations showed only 70%
conversion of SO2 to K2SO4. Actual laboratory data from petroleum coke yield much better results, however. The data indicates a conversion of greater than 95%.
Although the reason for the difference is not fully understood, it is believed that perhaps some of the potassium species may have vaporized, which would increase conversion of SO2 (because diffusion to a particle surface would not be necessary).
It is further believed that using K2C03 particles will facilitate adsorbing the SO2 from hot post-flame gases. Although, in a preferred embodiment described herein, K2C03 is injected with the coal, it is possible that this arrangement will cause the K2C03 to become too hot.
Excessive temperatures are expected to the K2C03 to melt and perhaps become sticky, therefore causing a deposition problem in the combustion chamber. However, because the data seem to indicate that there may have been some vaporization and consequent enhancement in the sulfur conversion to sulfur carbonate, it is possible that the vaporization may be beneficial.
In a more preferred embodiment, the K2CO3 is injected above the flame zone (primary combustion zone) in order to reduce fouling effects downstream. Thus, in the preferred embodiment illustrated in Fig. 3, potassium carbonate is introduced with the tertiary air, in a second combustion zone. Not only does this arrangement overcome the slagging of potassium carbonate that may occur when it is introduced directly into the flame, it provides an enhanced NOx reduction. The data suggests that NOX formation is decreased by the addition of the potassium carbonate, in a reaction of the type:
K2C03 + NOX -> K2N03 + CO2. (4) The mechanism by which this NOX reaction occurs is not fully understood.
However, in combination with the oxygen enrichment, this preferred embodiment seems to yield synergistic results.
Referring now to Figs. 1 through 3, three preferred embodiments of a burner are shown in schematic fashion. As shown schematically in Fig. 1, a combustion chamber 20 is shown having a first or primary combustion zone 22 and a second or secondary combustion zone 24.
The first of the three inlet streams, the primary stream 26, combines the primary oxidant air with the solid, pulverized fuel, and thereby conveys the pulverized solid fuel into the combustion chamber 20 in the primary combustion zone 22. In an application where the fuel is not solid, the primary inlet stream can be eliminated. The secondary stream 28 introduces the secondary oxidant into the burner, around or near the primary stream 26, and into the primary combustion zone 22. The tertiary stream 32, is injected, if necessary, in the secondary combustion zone 24, to complete combustion. It is understood that in these apparatus, multiple air streams of each type thus described (primary, secondary and tertiary) can be utilized - indeed multiple burners can be used; the following description will refer to each in the singular for simplicity).
As shown in Fig. 1, oxygen enrichment is employed iii the primary and secondary oxidant streams, and the potassium carbonate is introduced with the fuel. As shown in Fig. 2, oxygen enrichment is employed in all three oxidant streams, and the potassium carbonate is introduced with the fuel. As shown in Fig. 3, oxygen enrichment is employed in all three oxidant streams, and the potassium carbonate is introduced with the tertiary oxidant into the secondary combustion zone.
Flue gas 34 is formed and exhausted from the combustion chamber 20. Thus, the first combustion zone is the zone where the fuel reacts around the burner level.
Secondary zones are sometimes desirable if 02 is provided downstream from the burner before the furnace exit to provide more complete combustion downstream. The oxygen equivalent amount of oxidant is adjusted in the oxidant streams (primary, secondary and, if applicable, tertiary oxidant) to maintain a predetermined amount of excess oxygen in view of the stoichiometric balance needed to complete combustion. This amount of excess oxygen is preferably maintained so that the 02 content of the flue gas is maintained between 1.5 percent and 4.5 percent, and more preferably between 2.5 percent and 3.5 percent, and most preferably about 3.0 percent.
For purposes of this application, all 02 contents are stated by volume of dry gas (excluding H20).
Thus, the preferred embodiments disclose processes designed to reduce NOX and SOX
emissions in boilers, particularly in coal-fired boilers. These embodiments comprise introducing potassium carbonate in the combustion process, at the burner level or above the burners, in conjunction with oxygen enrichment. By using this process, the SOX
levels can be reduced to a few ppm, even for high-sulfur fuels such as Midwestern coals and pet coke. At the same time, the NO. reducing effect of the oxygen enrichment will be significantly enhanced by the potassium carbonate, resulting in a low NOX process. Due to the slagging effect of the high temperature on the potassium carbonate, a staged combustion process may be preferred. Potassium sulfate can be scrubbed from the flue gas and can be sold as a fertilizer.
Fig. 1 illustrates a first preferred embodiment. The boiler using a solid fuel, such as pet-coke or coal, and utilizes three oxidant streams - primary for fuel transport, secondary for combustion, and tertiary for staged combustion. Note that, as adapted to a liquid fuel-burning apparatus, the primary oxidant stream may be unnecessary.
As shown, the process works to reduce NOX emissions by controlling temperature at the burner level, and further due to the introduction of the potassium carbonate in the boiler at the same level with the fuel. By controlling the temperature and limiting it from becoming too high, to avoid NOX production, potassium carbonate slagging will be reduced or perhaps completely avoided. Oxygen is injected at the primary/secondary oxidant level, in order to initiate the combustion process faster and more efficient than with air alone (particularly under fuel-rich conditions).
It is noted that, as less air will be used at the primary/secondary oxidant level, the combustion will be less efficient. Under these circumstances, oxygen offers a clear way to balance this effect, due to the enhanced reactivity when compared to air combustion.
Additionally, the presence of the oxygen in the primary combustion zone is even more desirable when low-volatile fuels are implemented, such as anthracite or pet-coke. Finally, the use of an oxygen-enriched oxidant in the primary combustion zone will heat the fuel quicker, and will allow the nitrogen to be released in pure form, rather than being transformed in nitric oxide.
The preferred embodiment illustrated in Fig. 2 shows an alternative process for improving combustion efficiency by improving the oxygen-fuel mixing at the burner level between the fuel and oxidant. In the embodiment of Fig. 2, oxygen enrichment is introduced at the tertiary oxidant level as well, to enhance combustion at the secondary combustion zone.
Referring now to Fig. 3, potassium carbonate is injected into the boiler at the tertiary oxidant level. By injecting the potassium carbonate in the secondary combustion zone, the higher-temperature environment at the burner level is avoided. The potassium carbonate can be injected through the air stream, or even better, through the oxygen stream (where an oxygen lance is used), due to the higher flow velocities, yielding better mixing with the flue gas stream. Alternately, oxygen can be introduced only at the primary/secondary oxidant level, for NO,, control.
It is preferred that the quantities of potassium carbonate used be selected to comport with the stoichiometry defined by the sulfur content in the fuel. In a preferred embodiment, the potassium carbonate is introduced into the combustion chamber in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between about 0% and about 50%. In a more preferred embodiment, the excess is between about 10%
and about 50%. In a most preferred embodiment, the excess is between about 20%
and about 35%. As shown by the data, the process results in at least half of the sulfur in the sulfur-containing fuel being converted to potassium sulfate. Oxygen is used such as to replace less than 10-20% of the overall oxidant, in a relationship between the primary/secondary oxidant stream and tertiary stream such as to minimize the NO% formation and unburnt fuel in the ash.
Thus, in a preferred embodiment, a process for burning a sulfur-containing fuel to produce a flue gas is disclosed. A sulfur-containing fuel is introduced into a combustion chamber at a fuel inlet. A primary oxidant stream containing more than 21% oxygen is introduced into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone. A
secondary oxidant stream containing more than 21% oxygen is introduced into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone. A tertiary oxidant stream containing more than 21 % oxygen is introduced into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet. The tertiary oxidant enters the combustion chamber to define a secondary combustion zone.
The total oxygen content of the oxidant entering the combustion chamber exceeds 21%.
Potassium carbonate is introduced into the combustion chamber through the tertiary air inlet in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate. At least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.
Still another aspect of the present invention is to provide a process for burning sulfur-containing fuels that can be successively modified to provide adequate combustion characteristics resulting in adequate reduction of SOX formation sufficient to meet environmental guidelines without expensive and complex SO, treatment apparatus, such as scrubbers, etc.
Another aspect of the present invention is to provide a process for burning sulfur-containing fuels that can be successively modified to provide adequate combustion characteristics resulting in adequate reduction of NOX formation sufficient to meet environmental guidelines without expensive and complex NOX treatment apparatus.
An even further aspect of the present invention is to provide a process for burning sulfur-containing fuels that provides a means for chemically preventing the formation of SO, and concurrently provides a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
Another aspect of the present invention is to provide a process for burning sulfur-containing fuels that provides a means for chemically preventing the formation of NOX, and concurrently provides a mechanism to avoid problems associated with slagging or other fouling of the combustion equipment.
Another aspect of the present invention is to provide a process for burning a sulfur-containing fuel to produce a flue gas, the process comprising: introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet; oxygen-enriching at least one oxidant stream;
introducing a primary oxidant stream into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone;
introducing a secondary oxidant stream into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion 3a zone; introducing a tertiary oxidant stream into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zonethe tertiary oxidant stream completing combustion of the sulfur-containing fuel;
introducing potassium carbonate into the combustion chamber via the tertiary oxidant stream; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the oxidant entering the combustion chamber exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the primary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the secondary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the tertiary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the potassium carbonate is introduced into the combustion chamber in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%.
Another aspect of the present invention is to provide a process of the present invention wherein at least half' of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
Another aspect of the present invention is to provide a process of the present invention wherein the potassium carbonate is introduced into the combustion chamber through the fuel inlet.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the primary oxidant exceeds 21 %.
3b Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the secondary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process of the present invention wherein the total oxygen content of the tertiary oxidant exceeds 21 %.
Another aspect of the present invention is to provide a process for burning a sulfur-containing fuel to produce a flue gas, the process comprising: introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet; introducing a primary oxidant stream containing more than 21 % oxygen into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone; introducing a secondary oxidant stream containing more than 21 % oxygen into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone; introducing a tertiary oxidant stream containing more than 21 %
oxygen into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zone; the total oxygen content of the oxidant entering the combustion chamber exceeding 21 %; introducing potassium carbonate into the combustion chamber through the tertiary air inlet in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate; wherein at least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
These and other aspects, advantages and features of the present invention will be apparent from the detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description that follows, reference will be made to the following figures:
Fig. 1 is a schematic illustration of a first preferred embodiment of a process for burning a sulfur-containing fuel;
WO 2004/087301 PCTlIB2004/000928 Fig. 2 is a schematic illustration of a second preferred embodiment of a process for burning a sulfur-containing fuel;
Fig. 3 is a schematic illustration of a third preferred embodiment of a process for burning a sulfur-containing fuel; and Fig. 4 is a graph illustrating data of theoretical data expected from burning a sulfur containing fuel according to a preferred embodiment of a process for burning sulfur-containing fuel.
DESCRIPTION OF PREFERRED EMBODIMENTS
In its simplest application, a process for burning a sulfur-containing fuel to produce a flue gas is disclosed. The process comprises introducing a sulfur-containing fuel into a combustion chamber, introducing an oxidant stream into the combustion chamber and mixing it with the sulfur-containing fuel to define a combustion zone, and introducing potassium carbonate into the combustion chamber. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate.
In the preferred embodiments, a combustion subassembly uses at least two, and sometimes three, oxidant streams. In the example in which coal is the sulfur-containing fuel, oxygen enrichment is employed to reduce NOR, as is more fully described in United States Patent Publication Number US 2004-0185404 Al.
In the preferred embodiments, a process designed to reduce SOX emissions in boilers, particularly in coal-fired boilers, is disclosed. The process includes introducing potassium carbonate in the combustion process, at the burner level or above the burners.
When used in conjunction with oxygen enrichment, NO,, reduction can be achieved, to an even greater degree than is expected by using oxygen enrichment alone. By this process, SOX
levels can be reduced to a few ppm, even for high-sulfur fuels such as Midwestern coals and pet coke.
At the same time, the NO,, reducing effect of the oxygen enrichment is enhanced by the potassium carbonate, resulting in a low NO. process. To avoid slagging effect of the high temperature on the potassium carbonate, a staged combustion process is most preferred.
Laboratory test data illustrates just a portion of the expected benefits in removing sulfur from pet-coke combustion using potassium carbonate. Test results show that the flue gas of both air-combustion (traditional) and oxy-combustion (oxygen enriched) contained approximately 6 ppm SO,,. This is extremely low in view of the fact that the pet-coke used contained approximately 3-6% sulfur. The reaction taking place in the combustion process is:
K2C03 + SO, -> K2S04 + C02. (1) Recent calculations made of the adsorption of SO2 by K2C03 in a pulverized coal boiler fired with Illinois No. 6 coal are illustrated as follows. It was assumed that one million pounds per hour of coal, corresponding to approximately 1000 MW power production, was to be burned with 10% excess air. An elemental composition of the parent coal reveals:
Element Wt% daf C 77.32 H 5,33 N 1.49 0 8.88 S 6.98 The coal was assumed to have 10% ash, and moisture was neglected. Note that the sulfur composition for this coal is high (approximately 7 wt.% daf). The adsorption rate was assumed to be limited by the diffusion of SO2 to the surface of the particle.
The mass transfer rate is:
N502 = h, (C5o2,g - Cs02,5) (2) where N 02 is the molar flux of SO2 to the particle surface per external surface area of particle, hm is the convective mass transfer coefficient, and CS02 is the concentration of gas in either the bulk gas phase or at the surface. Under diffusion-limited conditions, Cso2s is essentially zero, and equation (2) becomes very simple. The mass transfer coefficient is calculated from the Sherwood number, which is 2.0 for small particles:
Sh = hn,dn (3) DSO2-air where dp is the particle diameter, assumed to be 50 microns in this calculation. The diffusivity of SO2 was calculated from the Chapman-Enskog theory for kinetic gases. The parameters for air were used, since they are similar to post-combustion gases.
The diffusivity changes as a function of temperature.
For this calculation, a temperature profile was assumed. The particle and gas temperature started at 2000 K and then decreased in a linear fashion to 1000 K after one second. This is thought to approximate the conditions in most pulverized coal boilers.
The initial concentration of SO2 was calculated from the flow rates of coal and air, assuming that all of the sulfur in the coal ended up as SO2. This yielded a calculation of about 4510 ppm. The differential equation for the change in SO2 concentration in this case is:
dCs02 = n Ap NsOZ (3) dt where np is the particle number density (number of particles per cubic meter), Ap is the external area per particle (4 tr p2), and Ns02 is from equation (2).
The resulting SO2 profile is shown in Fig. 4. As shown, the calculations showed only 70%
conversion of SO2 to K2SO4. Actual laboratory data from petroleum coke yield much better results, however. The data indicates a conversion of greater than 95%.
Although the reason for the difference is not fully understood, it is believed that perhaps some of the potassium species may have vaporized, which would increase conversion of SO2 (because diffusion to a particle surface would not be necessary).
It is further believed that using K2C03 particles will facilitate adsorbing the SO2 from hot post-flame gases. Although, in a preferred embodiment described herein, K2C03 is injected with the coal, it is possible that this arrangement will cause the K2C03 to become too hot.
Excessive temperatures are expected to the K2C03 to melt and perhaps become sticky, therefore causing a deposition problem in the combustion chamber. However, because the data seem to indicate that there may have been some vaporization and consequent enhancement in the sulfur conversion to sulfur carbonate, it is possible that the vaporization may be beneficial.
In a more preferred embodiment, the K2CO3 is injected above the flame zone (primary combustion zone) in order to reduce fouling effects downstream. Thus, in the preferred embodiment illustrated in Fig. 3, potassium carbonate is introduced with the tertiary air, in a second combustion zone. Not only does this arrangement overcome the slagging of potassium carbonate that may occur when it is introduced directly into the flame, it provides an enhanced NOx reduction. The data suggests that NOX formation is decreased by the addition of the potassium carbonate, in a reaction of the type:
K2C03 + NOX -> K2N03 + CO2. (4) The mechanism by which this NOX reaction occurs is not fully understood.
However, in combination with the oxygen enrichment, this preferred embodiment seems to yield synergistic results.
Referring now to Figs. 1 through 3, three preferred embodiments of a burner are shown in schematic fashion. As shown schematically in Fig. 1, a combustion chamber 20 is shown having a first or primary combustion zone 22 and a second or secondary combustion zone 24.
The first of the three inlet streams, the primary stream 26, combines the primary oxidant air with the solid, pulverized fuel, and thereby conveys the pulverized solid fuel into the combustion chamber 20 in the primary combustion zone 22. In an application where the fuel is not solid, the primary inlet stream can be eliminated. The secondary stream 28 introduces the secondary oxidant into the burner, around or near the primary stream 26, and into the primary combustion zone 22. The tertiary stream 32, is injected, if necessary, in the secondary combustion zone 24, to complete combustion. It is understood that in these apparatus, multiple air streams of each type thus described (primary, secondary and tertiary) can be utilized - indeed multiple burners can be used; the following description will refer to each in the singular for simplicity).
As shown in Fig. 1, oxygen enrichment is employed iii the primary and secondary oxidant streams, and the potassium carbonate is introduced with the fuel. As shown in Fig. 2, oxygen enrichment is employed in all three oxidant streams, and the potassium carbonate is introduced with the fuel. As shown in Fig. 3, oxygen enrichment is employed in all three oxidant streams, and the potassium carbonate is introduced with the tertiary oxidant into the secondary combustion zone.
Flue gas 34 is formed and exhausted from the combustion chamber 20. Thus, the first combustion zone is the zone where the fuel reacts around the burner level.
Secondary zones are sometimes desirable if 02 is provided downstream from the burner before the furnace exit to provide more complete combustion downstream. The oxygen equivalent amount of oxidant is adjusted in the oxidant streams (primary, secondary and, if applicable, tertiary oxidant) to maintain a predetermined amount of excess oxygen in view of the stoichiometric balance needed to complete combustion. This amount of excess oxygen is preferably maintained so that the 02 content of the flue gas is maintained between 1.5 percent and 4.5 percent, and more preferably between 2.5 percent and 3.5 percent, and most preferably about 3.0 percent.
For purposes of this application, all 02 contents are stated by volume of dry gas (excluding H20).
Thus, the preferred embodiments disclose processes designed to reduce NOX and SOX
emissions in boilers, particularly in coal-fired boilers. These embodiments comprise introducing potassium carbonate in the combustion process, at the burner level or above the burners, in conjunction with oxygen enrichment. By using this process, the SOX
levels can be reduced to a few ppm, even for high-sulfur fuels such as Midwestern coals and pet coke. At the same time, the NO. reducing effect of the oxygen enrichment will be significantly enhanced by the potassium carbonate, resulting in a low NOX process. Due to the slagging effect of the high temperature on the potassium carbonate, a staged combustion process may be preferred. Potassium sulfate can be scrubbed from the flue gas and can be sold as a fertilizer.
Fig. 1 illustrates a first preferred embodiment. The boiler using a solid fuel, such as pet-coke or coal, and utilizes three oxidant streams - primary for fuel transport, secondary for combustion, and tertiary for staged combustion. Note that, as adapted to a liquid fuel-burning apparatus, the primary oxidant stream may be unnecessary.
As shown, the process works to reduce NOX emissions by controlling temperature at the burner level, and further due to the introduction of the potassium carbonate in the boiler at the same level with the fuel. By controlling the temperature and limiting it from becoming too high, to avoid NOX production, potassium carbonate slagging will be reduced or perhaps completely avoided. Oxygen is injected at the primary/secondary oxidant level, in order to initiate the combustion process faster and more efficient than with air alone (particularly under fuel-rich conditions).
It is noted that, as less air will be used at the primary/secondary oxidant level, the combustion will be less efficient. Under these circumstances, oxygen offers a clear way to balance this effect, due to the enhanced reactivity when compared to air combustion.
Additionally, the presence of the oxygen in the primary combustion zone is even more desirable when low-volatile fuels are implemented, such as anthracite or pet-coke. Finally, the use of an oxygen-enriched oxidant in the primary combustion zone will heat the fuel quicker, and will allow the nitrogen to be released in pure form, rather than being transformed in nitric oxide.
The preferred embodiment illustrated in Fig. 2 shows an alternative process for improving combustion efficiency by improving the oxygen-fuel mixing at the burner level between the fuel and oxidant. In the embodiment of Fig. 2, oxygen enrichment is introduced at the tertiary oxidant level as well, to enhance combustion at the secondary combustion zone.
Referring now to Fig. 3, potassium carbonate is injected into the boiler at the tertiary oxidant level. By injecting the potassium carbonate in the secondary combustion zone, the higher-temperature environment at the burner level is avoided. The potassium carbonate can be injected through the air stream, or even better, through the oxygen stream (where an oxygen lance is used), due to the higher flow velocities, yielding better mixing with the flue gas stream. Alternately, oxygen can be introduced only at the primary/secondary oxidant level, for NO,, control.
It is preferred that the quantities of potassium carbonate used be selected to comport with the stoichiometry defined by the sulfur content in the fuel. In a preferred embodiment, the potassium carbonate is introduced into the combustion chamber in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between about 0% and about 50%. In a more preferred embodiment, the excess is between about 10%
and about 50%. In a most preferred embodiment, the excess is between about 20%
and about 35%. As shown by the data, the process results in at least half of the sulfur in the sulfur-containing fuel being converted to potassium sulfate. Oxygen is used such as to replace less than 10-20% of the overall oxidant, in a relationship between the primary/secondary oxidant stream and tertiary stream such as to minimize the NO% formation and unburnt fuel in the ash.
Thus, in a preferred embodiment, a process for burning a sulfur-containing fuel to produce a flue gas is disclosed. A sulfur-containing fuel is introduced into a combustion chamber at a fuel inlet. A primary oxidant stream containing more than 21% oxygen is introduced into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone. A
secondary oxidant stream containing more than 21% oxygen is introduced into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone. A tertiary oxidant stream containing more than 21 % oxygen is introduced into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet. The tertiary oxidant enters the combustion chamber to define a secondary combustion zone.
The total oxygen content of the oxidant entering the combustion chamber exceeds 21%.
Potassium carbonate is introduced into the combustion chamber through the tertiary air inlet in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%. The sulfur-containing fuel is burned to produce the flue gas and potassium sulfate. At least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.
Claims (12)
1. A process for burning a sulfur-containing fuel to produce a flue gas, the process comprising:
introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet;
oxygen-enriching at least one oxidant stream;
introducing a primary oxidant stream into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone;
introducing a secondary oxidant stream into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone;
introducing a tertiary oxidant stream into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zone, the tertiary oxidant stream completing combustion of the sulfur-containing fuel;
introducing potassium carbonate into the combustion chamber via the tertiary oxidant stream; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate.
introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet;
oxygen-enriching at least one oxidant stream;
introducing a primary oxidant stream into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone;
introducing a secondary oxidant stream into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone;
introducing a tertiary oxidant stream into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zone, the tertiary oxidant stream completing combustion of the sulfur-containing fuel;
introducing potassium carbonate into the combustion chamber via the tertiary oxidant stream; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate.
2. The process of Claim 1 wherein the total oxygen content of the oxidant entering the combustion chamber exceeds 21%.
3. The process of Claim 2 wherein the total oxygen content of the primary oxidant exceeds 21%.
4. The process of Claim 2 wherein the total oxygen content of the secondary oxidant exceeds 21%.
5. The process of Claim 2 wherein the total oxygen content of the tertiary oxidant exceeds 21%.
6. The process of Claim 2 wherein the potassium carbonate is introduced into the combustion chamber in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%.
7. The process of Claim 2 wherein at least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
8. The process of Claim 2 wherein the potassium carbonate is introduced into the combustion chamber through the fuel inlet.
9. The process of Claim 8 wherein the total oxygen content of the primary oxidant exceeds 21%.
10. The process of Claim 9 wherein the total oxygen content of the secondary oxidant exceeds 21%.
11. The process of Claim 10 wherein the total oxygen content of the tertiary oxidant exceeds 21%.
12. A process for burning a sulfur-containing fuel to produce a flue gas, the process comprising:
introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet;
introducing a primary oxidant stream containing more than 21% oxygen into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone;
introducing a secondary oxidant stream containing more than 21% oxygen into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone;
introducing a tertiary oxidant stream containing more than 21% oxygen into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zone;
the total oxygen content of the oxidant entering the combustion chamber exceeding 21%;
introducing potassium carbonate into the combustion chamber through the tertiary air inlet in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate;
wherein at least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
introducing a sulfur-containing fuel into a combustion chamber at a fuel inlet;
introducing a primary oxidant stream containing more than 21% oxygen into the combustion chamber at a primary oxidant inlet positioned proximate to or coincident the fuel inlet and mixing it with the sulfur-containing fuel to define a first combustion zone;
introducing a secondary oxidant stream containing more than 21% oxygen into the combustion chamber at a secondary oxidant inlet positioned so that the secondary oxidant enters the combustion chamber in the primary combustion zone;
introducing a tertiary oxidant stream containing more than 21% oxygen into the combustion chamber at a tertiary oxidant inlet positioned away from the primary oxidant inlet and away from the secondary oxidant inlet, the tertiary oxidant entering the combustion chamber to define a secondary combustion zone;
the total oxygen content of the oxidant entering the combustion chamber exceeding 21%;
introducing potassium carbonate into the combustion chamber through the tertiary air inlet in an amount sufficient to exceed the stoichiometric requirement needed to react with the sulfur in the fuel by between 0% and 50%; and burning the sulfur-containing fuel to produce the flue gas and potassium sulfate;
wherein at least half of the sulfur in the sulfur-containing fuel is converted to potassium sulfate.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US46068003P | 2003-04-04 | 2003-04-04 | |
| US60/460,680 | 2003-04-04 | ||
| US10/779,474 | 2004-02-13 | ||
| US10/779,474 US20040229176A1 (en) | 2003-04-04 | 2004-02-13 | Process for burning sulfur-containing fuels |
| PCT/IB2004/000928 WO2004087301A1 (en) | 2003-04-04 | 2004-03-22 | Process for burning sulfur-containing fuels |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2521183A1 CA2521183A1 (en) | 2004-10-14 |
| CA2521183C true CA2521183C (en) | 2012-05-01 |
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ID=33135142
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2521183A Expired - Fee Related CA2521183C (en) | 2003-04-04 | 2004-03-22 | Process for burning sulfur-containing fuels |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US20040229176A1 (en) |
| EP (1) | EP1613416A1 (en) |
| JP (1) | JP4382809B2 (en) |
| AU (1) | AU2004226590B2 (en) |
| CA (1) | CA2521183C (en) |
| WO (1) | WO2004087301A1 (en) |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4226601A (en) * | 1977-01-03 | 1980-10-07 | Atlantic Richfield Company | Process for reducing sulfur contaminant emissions from burning coal or lignite that contains sulfur |
| US4201753A (en) * | 1978-01-26 | 1980-05-06 | Gilbert Associates, Inc. | Flue gas desulfurization process |
| JPS5822073B2 (en) * | 1980-01-08 | 1983-05-06 | 秋本 信吉 | Treatment method for sulfur-containing fuel |
| US4523532A (en) * | 1982-02-02 | 1985-06-18 | Rockwell International Corporation | Combustion method |
| US4519807A (en) * | 1982-03-17 | 1985-05-28 | Matsushita Electric Industrial Co., Ltd. | Carbonaceous solid fuel |
| US4540554A (en) * | 1984-06-05 | 1985-09-10 | Dayen William R | Removal of Sox, Nox, and particulate from combusted carbonaceous fuels |
| DE3444469C1 (en) * | 1984-12-06 | 1986-06-19 | L. & C. Steinmüller GmbH, 5270 Gummersbach | Process and round burner for injecting aqueous additive suspensions in the center of a round burner |
| US5335609A (en) * | 1993-04-29 | 1994-08-09 | University Of Chicago | Thermal and chemical remediation of mixed waste |
| US5605452A (en) * | 1995-06-06 | 1997-02-25 | North American Manufacturing Company | Method and apparatus for controlling staged combustion systems |
| US5967061A (en) * | 1997-01-14 | 1999-10-19 | Energy And Environmental Research Corporation | Method and system for reducing nitrogen oxide and sulfur oxide emissions from carbonaceous fuel combustion flue gases |
-
2004
- 2004-02-13 US US10/779,474 patent/US20040229176A1/en not_active Abandoned
- 2004-03-22 WO PCT/IB2004/000928 patent/WO2004087301A1/en active Application Filing
- 2004-03-22 CA CA2521183A patent/CA2521183C/en not_active Expired - Fee Related
- 2004-03-22 AU AU2004226590A patent/AU2004226590B2/en not_active Ceased
- 2004-03-22 JP JP2006506398A patent/JP4382809B2/en not_active Expired - Fee Related
- 2004-03-22 EP EP04722347A patent/EP1613416A1/en not_active Withdrawn
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| JP2006526752A (en) | 2006-11-24 |
| US20040229176A1 (en) | 2004-11-18 |
| AU2004226590B2 (en) | 2009-07-23 |
| WO2004087301A1 (en) | 2004-10-14 |
| CA2521183A1 (en) | 2004-10-14 |
| EP1613416A1 (en) | 2006-01-11 |
| AU2004226590A1 (en) | 2004-10-14 |
| JP4382809B2 (en) | 2009-12-16 |
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