US20080105176A1 - Staged-coal injection for boiler reliability and emissions reduction - Google Patents
Staged-coal injection for boiler reliability and emissions reduction Download PDFInfo
- Publication number
- US20080105176A1 US20080105176A1 US11/557,733 US55773306A US2008105176A1 US 20080105176 A1 US20080105176 A1 US 20080105176A1 US 55773306 A US55773306 A US 55773306A US 2008105176 A1 US2008105176 A1 US 2008105176A1
- Authority
- US
- United States
- Prior art keywords
- coal
- type
- zone
- burner
- combustion
- 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
Links
- 239000003245 coal Substances 0.000 title claims abstract description 155
- 238000002347 injection Methods 0.000 title abstract description 8
- 239000007924 injection Substances 0.000 title abstract description 8
- 230000009467 reduction Effects 0.000 title description 5
- 238000002485 combustion reaction Methods 0.000 claims description 40
- 150000001875 compounds Chemical class 0.000 claims description 27
- 238000009841 combustion method Methods 0.000 claims description 24
- 239000003513 alkali Substances 0.000 claims description 14
- 239000002802 bituminous coal Substances 0.000 claims description 11
- 150000001805 chlorine compounds Chemical class 0.000 claims description 11
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 8
- 239000000460 chlorine Substances 0.000 claims description 8
- 229910052801 chlorine Inorganic materials 0.000 claims description 8
- 238000003860 storage Methods 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 26
- 238000010248 power generation Methods 0.000 abstract description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 29
- 230000015572 biosynthetic process Effects 0.000 description 11
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 10
- 229910052753 mercury Inorganic materials 0.000 description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 7
- 239000002245 particle Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 230000001965 increasing effect Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- LWJROJCJINYWOX-UHFFFAOYSA-L mercury dichloride Chemical compound Cl[Hg]Cl LWJROJCJINYWOX-UHFFFAOYSA-L 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229960002523 mercuric chloride Drugs 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- -1 ash particles Chemical compound 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000003039 volatile agent Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
- F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
- F23C6/045—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure
- F23C6/047—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure with fuel supply in stages
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D1/00—Burners for combustion of pulverulent fuel
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C2201/00—Staged combustion
- F23C2201/10—Furnace staging
- F23C2201/101—Furnace staging in vertical direction, e.g. alternating lean and rich zones
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C2201/00—Staged combustion
- F23C2201/30—Staged fuel supply
- F23C2201/301—Staged fuel supply with different fuels in stages
Definitions
- the present invention relates to the field of power generation.
- the invention relates to a staged-coal injection procedure for coal-fired boilers used for power generation.
- PRB coal is relatively low in cost, has a low sulfur content, and is in reliable supply. It also has a higher reactivity than eastern bituminous coal due to a lower fixed carbon-to-volatile ratio. This results in lower NOx and UBC emissions.
- the volatile portion of PRB coal carries a significant amount of nitrogen, and under staged combustion, the volatiles are released early in the combustion process and burned in the overfire air zone, resulting in a lower potential to form NOx.
- PRB coal has a higher moisture content, a lower energy content, and a different ash composition than eastern bituminous coal.
- the higher moisture content and lower energy content results in the need to burn larger quantities of PRB coal than eastern bituminous coal to produce the same amount of energy.
- Blending PRB coal and eastern bituminous coal provides the added energy content of the eastern bituminous coal, the lower NOx and UBC emissions of PRB coal, and a reduction in ash deposition.
- boiler tube fireside corrosion can be a significant problem due to the formation of alkali chloride compounds which attach to the boiler tube surface, especially in a reducing environment such as that caused by staged combustion. The deposition of these compounds also subtracts from the formation of oxidized mercury (HgCl 2 ), which is important to facilitate the downstream removal of mercury. By minimizing the formation of alkali chlorides, more chloride may be available to form mercuric chloride in the flue gas.
- UBC unburned carbon
- a coal combustion method including the steps of combusting a first type of coal in a first zone of a furnace, and combusting a second type of coal in a second zone of the furnace, the second zone being at a position above the first zone.
- the first type of coal has a high alkali content.
- the second type of coal has a high chlorine content.
- the method includes the steps of feeding the first type of coal to fed to a first burner for combustion in the first zone of the furnace, and feeding the second type of coal to a second burner for combustion in the second zone of the furnace.
- the first burner is optimized to combust the first type of coal and the second burner is optimized to combust the second type of coal.
- a coal combustion method includes the steps of providing a first type of coal including a selected first compound; providing a second type of coal including a selected second compound; combusting the first type of coal in a first zone of a furnace; and combusting the second type of coal in a second zone of the furnace.
- the first and second zones are positioned so as to substantially prevent the first compound from combining with the second compound during combustion of the first and second types of coals.
- the first compound is an alkali compound and the second compound is a chloride compound.
- the method includes the steps of feeding the first type of coal to a first burner for combustion in the first zone and feeding the second type of coal to a second burner for combustion in the second zone.
- the method includes the step of providing overfire air in a third zone of the furnace to aid in complete combustion of the first type of coal and second type of coal.
- a coal combustion method includes the steps of providing a boiler having a furnace section, a first burner positioned in a first zone of the furnace section, and a second burner positioned in a second zone of the furnace section.
- the method further includes the steps of feeding a first type of coal including a selected first compound to the first burner, combusting the first type of coal in a first zone of the furnace section, feeding a second type of coal to the second burner, and combusting the second type of coal in a second zone of the furnace section.
- the first compound is consumed in the first zone so as to be substantially unavailable for reaction in the second zone.
- the first compound is an alkali compound.
- the second type of coal is an eastern bituminous coal.
- the second compound is a chloride compound.
- the method includes the step of feeding the first type of coal from a first storage hopper to a first pulverizer where the first type of coal is pulverized.
- the method includes the step of feeding the second type of coal from a second storage hopper to a second pulverizer where the second type of coal is pulverized.
- the method includes the step of providing a combustion air to the first burner, second burner, and an overfire port.
- the amount of combustion air provided to the first burner is less than the amount of air provided to the second burner.
- the overfire port introduces combustion air into a third zone of the furnace to aid in complete combustion of the first and second types of coal.
- FIG. 1 shows a prior art staged-coal boiler
- FIG. 2 shows a staged-coal boiler adapted to use a staging procedure according to an embodiment of the invention
- FIG. 3 is schematic of the staging procedure for the staged-coal boiler of FIG. 1 .
- FIG. 1 a prior art staged-coal boiler is illustrated in FIG. 1 and shown generally at reference numeral 10 .
- the boiler 10 includes a hopper 11 for storing and feeding coal to a pulverizer 12 , a blower 13 for delivering the pulverized coal and transport air (primary air) mix and secondary combustion air to a burner 16 , a furnace section 17 for combusting the coal therein, a boiler tube section 18 for absorbing heat created by the combustion of the coal to create steam, and an economizer and bag section 20 for cooling the flue gas exiting the furnace section 17 and collecting ash particles.
- a hopper 11 for storing and feeding coal to a pulverizer 12
- a blower 13 for delivering the pulverized coal and transport air (primary air) mix and secondary combustion air to a burner 16
- a furnace section 17 for combusting the coal therein
- a boiler tube section 18 for absorbing heat created by the combustion of the coal to create steam
- the boiler 10 uses an air staging procedure by introducing overfire air through an overfire air port 14 into the furnace section 17 in a region above the burner 16 .
- combustion air provided by blower 13 is separated into primary (for coal transport), secondary (main burner), and tertiary (overfire) air flows. This encourages complete burnout and the formation of N2 instead of NOx.
- the combustion air may be separated into 70%-90% primary and secondary air and 10%-30% overfire or tertiary air.
- the primary and secondary air is mixed with the coal at the burner to produce a relatively low temperature, oxygen deficient, fuel rich zone that creates moderate amounts of NOx.
- the overfire or tertiary air is injected above the combustion zone where combustion is completed at an increased flame volume that limits the production of NOx.
- a staged-coal boiler adapted to use a staging procedure is illustrated and shown generally at reference numeral 100 . While the staging procedure is being discussed with a pulverized coal-type boiler, it should be appreciated that the staging procedure may be used with other suitable boilers, and that the pulverized coal-type boiler is being used as an example boiler for discussion purposes only.
- the boiler 100 includes a pair of coal hoppers 110 and 111 for storing and feeding coal to pulverizers 112 and 113 , respectively.
- the pulverizers 112 and 113 pulverize the coal for delivery to burners 114 and 115 .
- the coal is delivered to the burners 114 and 115 by a portion of the forced air from blowers 117 and 118 where the coal is mixed with the air from the blowers 117 and 118 in the burners 114 and 115 to combust the coal within a furnace section 120 of the boiler 100 .
- the blowers also provide overfire air through an overfire air port 125 for complete burnout. Heat created by the burners 114 and 115 in the furnace section 120 is absorbed by a boiler tube section 121 to create steam. Flue gas, including ash particles, exits the furnace section 120 and into an economizer and bag section 124 where the flue gas is cooled and the ash particles are collected.
- the boiler 100 uses a combination of air staging, like that discussed with reference to FIG. 1 , and fuel staging to minimize Nox formation, fireside corrosion and mercury (by maximizing mercury oxidation and PRB based carbon). This is done by injecting different types of coal at different levels/stages of the furnace section 120 as well as controlling the coal feed rates and size distribution.
- coal hopper 110 contains a higher chloride coal “C 1 ” (such as eastern bituminous coal) and coal hopper 111 contains a more reactive coal “C 2 ” with higher alkali and lower chloride content (such as PRB coal).
- the higher chlorine coal C 1 is delivered to pulverizer 112 where it is pulverized and delivered via a portion of the blower air to burner 114 for combustion.
- the more reactive coal C 2 is delivered to pulverizer 113 where it is pulverized and delivered by a portion of the blower air to burner 115 for combustion.
- the more reactive coal C 2 with higher alkali but low chlorine content is injected at a lower, deeper staged level of the furnace section 120 while the higher chloride coal C 1 is injected into an upper staged level of the furnace section 120 .
- This allows the chlorides in the higher chlorine coal C 1 to be separated from and less accessible to the alkali compounds in the more reactive coal C 2 , thereby increasing the interaction of the chlorides with mercury and decreasing the formation of alkali chloride compounds.
- the separation of the chlorides and alkali compounds can be seen in the flow of ash particles “AP 1 ” and “AP 2 ” of coals C 1 and C 2 , respectively.
- the ash particles AP 2 deposit on a lower section of a waterwall 123 of the furnace section 120 and the ash particles AP 1 deposit on a higher section of the waterwall 123 .
- Flue gas flows “F 1 ”, “F 2 ”, and “F 3 ” are also shown exiting the furnace section 120 .
- the amount of combustion air being used in the burners 114 and 115 is also different at the lower and upper staged levels of the furnace section 120 .
- the amount of air “A 2 ” used in burner 115 to combust the more reactive coal C 2 is lower than the amount of air “A 1 ” used in burner 114 to combust the higher chlorine coal.
- overfire air “A 3 ” is injected into the furnace section 120 in a region above the burners 114 and 115 to encourage complete burnout and the formation of N 2 instead of NOx.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion Of Fluid Fuel (AREA)
Abstract
A staged-coal injection procedure for coal-fired boilers used in power generation. The procedure includes the steps of combusting a first type of coal in a first zone of a furnace; and combusting a second type of coal in a second zone of the furnace. The second zone is at a position separate from the first zone.
Description
- The present invention relates to the field of power generation. In particular, the invention relates to a staged-coal injection procedure for coal-fired boilers used for power generation.
- As economical performance and compliance with stringent environmental regulations becomes increasingly important, energy companies must find cheaper ways to create power while reducing nitrogen oxides (NOx) and unburned carbon (UBC) emissions. One method currently being employed by energy companies is to use Powder River Basin (PRB) coal in boilers instead of eastern bituminous coal.
- PRB coal is relatively low in cost, has a low sulfur content, and is in reliable supply. It also has a higher reactivity than eastern bituminous coal due to a lower fixed carbon-to-volatile ratio. This results in lower NOx and UBC emissions. The volatile portion of PRB coal carries a significant amount of nitrogen, and under staged combustion, the volatiles are released early in the combustion process and burned in the overfire air zone, resulting in a lower potential to form NOx.
- Despite the lower cost and reduction in emissions associated with PRB coal, the use of PRB coal in boilers has created problems that can reduce the boiler's efficiency and reliability. PRB coal has a higher moisture content, a lower energy content, and a different ash composition than eastern bituminous coal. The higher moisture content and lower energy content results in the need to burn larger quantities of PRB coal than eastern bituminous coal to produce the same amount of energy. However, it is the ash composition of PRB coal that causes the greatest impact on boiler efficiency and reliability.
- While all coal-fired boilers experience some ash deposits, the ash composition of PRB coal can create special problems. Ash deposits formed from the combustion of PRB coal are difficult to remove, and may cause severe slagging and fouling on heating surfaces. As a result, deposits from the PRB coal can have a significant effect on the amount of heat absorbed by the boiler. This reduction of heat absorption in the boiler results in higher exit gas temperatures and in less heat being absorbed by the water walls. Thus, the superheater and reheater sections in the convection passes must absorb more heat to maintain full load steam conditions.
- Because the exit gas temperatures are higher, ash entering the convection passes is often above its fusion temperature, causing ash to deposit on the superheater and reheater surfaces and further reduce the ability of the boiler to make steam, thereby reducing the boiler's efficiency. Additionally, these higher temperatures may result in the production of NOx, thereby increasing emissions.
- One of the methods currently being used to reduce the negative effects of PRB coal while maintaining lower emissions of NOx and UBC is to blend PRB coal with eastern bituminous coal. Blending PRB coal and eastern bituminous coal provides the added energy content of the eastern bituminous coal, the lower NOx and UBC emissions of PRB coal, and a reduction in ash deposition. Although the benefits of blending are numerous, boiler tube fireside corrosion can be a significant problem due to the formation of alkali chloride compounds which attach to the boiler tube surface, especially in a reducing environment such as that caused by staged combustion. The deposition of these compounds also subtracts from the formation of oxidized mercury (HgCl2), which is important to facilitate the downstream removal of mercury. By minimizing the formation of alkali chlorides, more chloride may be available to form mercuric chloride in the flue gas.
- The formation of unburned carbon (UBC) during coal combustion also helps to reduce vapor mercury emissions due to the absorption of mercury on the carbon. Studies have shown that UBC formed from PRB coal is more reactive than those formed from bituminous coals. With staged combustion, the combustion of PRB coal can be better controlled to optimize the UBC formation for additional mercury capture.
- Accordingly, there is a need for a staged-coal injection procedure that provides the benefits of using PRB coal and eastern bituminous coal while reducing the formation of alkali chlorides.
- Therefore it is an object of the invention to provide a staged-coal injection procedure that reduces fireside corrosion.
- It is another object of the invention to provide a staged-coal injection procedure that minimizes mercury emissions by (1) enhancing the ability to form mercuric chloride, and (2) maximizing the formation of PRB based carbon in ash.
- It is another object of the invention to provide a staged-coal injection procedure that reduces the production of NOx.
- These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a coal combustion method including the steps of combusting a first type of coal in a first zone of a furnace, and combusting a second type of coal in a second zone of the furnace, the second zone being at a position above the first zone.
- According to another preferred embodiment of the invention, the first type of coal has a high alkali content.
- According to another preferred embodiment of the invention, the second type of coal has a high chlorine content.
- According to another preferred embodiment of the invention, the method includes the steps of feeding the first type of coal to fed to a first burner for combustion in the first zone of the furnace, and feeding the second type of coal to a second burner for combustion in the second zone of the furnace.
- According to another preferred embodiment of the invention, the first burner is optimized to combust the first type of coal and the second burner is optimized to combust the second type of coal.
- According to another preferred embodiment of the invention, a coal combustion method includes the steps of providing a first type of coal including a selected first compound; providing a second type of coal including a selected second compound; combusting the first type of coal in a first zone of a furnace; and combusting the second type of coal in a second zone of the furnace. The first and second zones are positioned so as to substantially prevent the first compound from combining with the second compound during combustion of the first and second types of coals.
- According to another preferred embodiment of the invention, the first compound is an alkali compound and the second compound is a chloride compound.
- According to another preferred embodiment of the invention, the method includes the steps of feeding the first type of coal to a first burner for combustion in the first zone and feeding the second type of coal to a second burner for combustion in the second zone.
- According to another preferred embodiment of the invention, the method includes the step of providing combustion air to the first burner and second burner. According to another preferred embodiment of the invention, the amount of combustion air provided to the first burner is less than the amount of air provided to the second burner.
- According to another preferred embodiment of the invention, the method includes the step of providing overfire air in a third zone of the furnace to aid in complete combustion of the first type of coal and second type of coal.
- According to another preferred embodiment of the invention, a coal combustion method is provided and includes the steps of providing a boiler having a furnace section, a first burner positioned in a first zone of the furnace section, and a second burner positioned in a second zone of the furnace section. The method further includes the steps of feeding a first type of coal including a selected first compound to the first burner, combusting the first type of coal in a first zone of the furnace section, feeding a second type of coal to the second burner, and combusting the second type of coal in a second zone of the furnace section. The first compound is consumed in the first zone so as to be substantially unavailable for reaction in the second zone.
- According to another preferred embodiment of the invention, the first type of coal is a Powder River Basin coal.
- According to another preferred embodiment of the invention, the first compound is an alkali compound.
- According to another preferred embodiment of the invention, the second type of coal is an eastern bituminous coal.
- According to another preferred embodiment of the invention, the second compound is a chloride compound.
- According to another preferred embodiment of the invention, the method includes the step of feeding the first type of coal from a first storage hopper to a first pulverizer where the first type of coal is pulverized.
- According to another preferred embodiment of the invention, the method includes the step of feeding the second type of coal from a second storage hopper to a second pulverizer where the second type of coal is pulverized.
- According to another preferred embodiment of the invention, the method includes the step of providing a combustion air to the first burner, second burner, and an overfire port.
- According to another preferred embodiment of the invention, the amount of combustion air provided to the first burner is less than the amount of air provided to the second burner.
- According to another preferred embodiment of the invention, the overfire port introduces combustion air into a third zone of the furnace to aid in complete combustion of the first and second types of coal.
- The invention may be best understood by reference to the following description in conjunction with the accompanying drawing figures in which:
-
FIG. 1 shows a prior art staged-coal boiler; -
FIG. 2 shows a staged-coal boiler adapted to use a staging procedure according to an embodiment of the invention; and -
FIG. 3 is schematic of the staging procedure for the staged-coal boiler ofFIG. 1 . - Referring now specifically to the drawings, a prior art staged-coal boiler is illustrated in
FIG. 1 and shown generally atreference numeral 10. Theboiler 10 includes ahopper 11 for storing and feeding coal to apulverizer 12, ablower 13 for delivering the pulverized coal and transport air (primary air) mix and secondary combustion air to aburner 16, afurnace section 17 for combusting the coal therein, aboiler tube section 18 for absorbing heat created by the combustion of the coal to create steam, and an economizer andbag section 20 for cooling the flue gas exiting thefurnace section 17 and collecting ash particles. - As illustrated, the
boiler 10 uses an air staging procedure by introducing overfire air through anoverfire air port 14 into thefurnace section 17 in a region above theburner 16. When using an air staging procedure, combustion air provided byblower 13 is separated into primary (for coal transport), secondary (main burner), and tertiary (overfire) air flows. This encourages complete burnout and the formation of N2 instead of NOx. - For example, the combustion air may be separated into 70%-90% primary and secondary air and 10%-30% overfire or tertiary air. The primary and secondary air is mixed with the coal at the burner to produce a relatively low temperature, oxygen deficient, fuel rich zone that creates moderate amounts of NOx. The overfire or tertiary air is injected above the combustion zone where combustion is completed at an increased flame volume that limits the production of NOx.
- Referring to
FIG. 2 , a staged-coal boiler adapted to use a staging procedure according to an embodiment of the invention is illustrated and shown generally atreference numeral 100. While the staging procedure is being discussed with a pulverized coal-type boiler, it should be appreciated that the staging procedure may be used with other suitable boilers, and that the pulverized coal-type boiler is being used as an example boiler for discussion purposes only. - The
boiler 100 includes a pair ofcoal hoppers pulverizers pulverizers burners burners blowers blowers burners furnace section 120 of theboiler 100. The blowers also provide overfire air through anoverfire air port 125 for complete burnout. Heat created by theburners furnace section 120 is absorbed by aboiler tube section 121 to create steam. Flue gas, including ash particles, exits thefurnace section 120 and into an economizer andbag section 124 where the flue gas is cooled and the ash particles are collected. - The
boiler 100 uses a combination of air staging, like that discussed with reference toFIG. 1 , and fuel staging to minimize Nox formation, fireside corrosion and mercury (by maximizing mercury oxidation and PRB based carbon). This is done by injecting different types of coal at different levels/stages of thefurnace section 120 as well as controlling the coal feed rates and size distribution. For example,coal hopper 110 contains a higher chloride coal “C1” (such as eastern bituminous coal) andcoal hopper 111 contains a more reactive coal “C2” with higher alkali and lower chloride content (such as PRB coal). The higher chlorine coal C1 is delivered to pulverizer 112 where it is pulverized and delivered via a portion of the blower air toburner 114 for combustion. The more reactive coal C2 is delivered to pulverizer 113 where it is pulverized and delivered by a portion of the blower air toburner 115 for combustion. - As illustrated in
FIG. 3 , the more reactive coal C2 with higher alkali but low chlorine content is injected at a lower, deeper staged level of thefurnace section 120 while the higher chloride coal C1 is injected into an upper staged level of thefurnace section 120. This allows the chlorides in the higher chlorine coal C1 to be separated from and less accessible to the alkali compounds in the more reactive coal C2, thereby increasing the interaction of the chlorides with mercury and decreasing the formation of alkali chloride compounds. The separation of the chlorides and alkali compounds can be seen in the flow of ash particles “AP1” and “AP2” of coals C1 and C2, respectively. As can be seen, the ash particles AP2 deposit on a lower section of awaterwall 123 of thefurnace section 120 and the ash particles AP1 deposit on a higher section of thewaterwall 123. Flue gas flows “F1”, “F2”, and “F3” are also shown exiting thefurnace section 120. - The amount of combustion air being used in the
burners furnace section 120. For example, the amount of air “A2” used inburner 115 to combust the more reactive coal C2 is lower than the amount of air “A1” used inburner 114 to combust the higher chlorine coal. In addition, overfire air “A3” is injected into thefurnace section 120 in a region above theburners - In addition to increased reaction with mercury, many other benefits may be obtained by using the staging procedure outlined above. For example, improved NOx reductions may be obtained due to the fact that the more reactive coal may be deeper staged without operability issues. The performance of the mill can also be optimized. By using different coals in separate burners, the burners can be optimized for that specific type of coal. Also, by using both higher chlorine coal and more reactive coal in a boiler, the benefits of both types of coals may be optimized while the problems associated with those coals may be minimized For example, the problems of slagging/fouling associated with more reactive coals may be minimized by replacing a portion of the more reactive coal with higher chlorine coal. The problem of NOx production associated with higher chloride coals may be minimized by replacing a portion of the higher chloride coal with more reactive coal. In addition, the amount of energy per unit weight of coal may be increased by replacing a portion of the more reactive coal with the higher chloride coal.
- A staged-coal injection procedure is described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiments of the invention and best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.
Claims (21)
1. A coal combustion method, comprising the steps of:
(a) combusting a first type of coal in a first zone of a furnace; and
(b) combusting a second type of coal in a second zone of the furnace, the second zone being at a position separate from the first zone.
2. The coal combustion method according to claim 1 , wherein the first type of coal has a substantially higher alkali content than the second type of coal.
3. The coal combustion method according to claim 1 , wherein the second type of coal has a substantially higher chlorine content than the first type of coal.
4. The coal combustion method according to claim 1 , and further including the steps of feeding the first type of coal to fed to a first burner for combustion in the first zone of the furnace and feeding the second type of coal to a second burner for combustion in the second zone of the furnace.
5. The coal combustion method according to claim 4 , wherein the first burner is adapted to combust the first type of coal and the second burner is adapted to combust the second type of coal.
6. A coal combustion method, comprising the steps of:
(a) providing a first type of coal including a selected first compound;
(b) providing a second type of coal including a selected second compound;
(c) combusting the first type of coal in a first zone of a furnace;
(d) combusting the second type of coal in a second zone of the furnace; and
(e) positioning the first and second zones in relation to each other so as to substantially prevent the first compound from combining with the second compound during combustion of the first and second types of coal.
7. The coal combustion method according to claim 6 , wherein the first compound is an alkali compound and the second compound is a chloride compound.
8. The coal combustion method according to claim 6 , and further including the steps of feeding the first type of coal to a first burner for combustion in the first zone and feeding the second type of coal to a second burner for combustion in the second zone.
9. The coal combustion method according to claim 8 , and further including the step of providing combustion air to the first burner and second burner.
10. The coal combustion method according to claim 9 , wherein the amount of combustion air provided to the first burner is less than the amount of air provided to the second burner.
11. The coal combustion method according to claim 6 , and further including the step of providing overfire air in a third zone of the furnace to aid in complete combustion of the first type of coal and second type of coal.
12. A coal combustion method, comprising the steps of:
(a) providing a boiler having:
(i) a furnace section;
(ii) a first burner positioned in a first zone of the furnace section; and
(iii) a second burner positioned in a second zone of the furnace section;
(a) feeding a first type of coal including a selected first compound to the first burner;
(b) combusting the first type of coal in a first zone of the furnace section; (c) feeding a second type of coal to the second burner;
(d) combusting the second type of coal in a second zone of the furnace section; and
(e) wherein the first compound is consumed in the first zone so as to be substantially unavailable for reaction in the second zone.
13. The coal combustion method according to claim 12 , wherein the first type of coal is a Powder River Basin coal.
14. The coal combustion method according to claim 12 , wherein the first compound is an alkali compound.
15. The coal combustion method according to claim 12 , wherein the second type of coal is an eastern bituminous coal.
16. The coal combustion method according to claim 12 , wherein the second compound is a chloride compound.
17. The coal combustion method according to claim 12 , and further including the step of feeding the first type of coal from a first storage hopper to a first pulverizer where the first type of coal is pulverized.
18. The coal combustion method according to claim 12 , and further including the step of feeding the second type of coal from a second storage hopper to a second pulverizer where the second type of coal is pulverized.
19. The coal combustion method according to claim 12 , and further including the step of providing a combustion air to the first burner, second burner, and an overfire port.
20. The coal combustion method according to claim 19 , wherein the amount of combustion air provided to the first burner is less than the amount of air provided to the second burner.
21. The coal combustion method according to claim 19 , wherein the overfire port is adapted to introduce combustion air into a third zone of the furnace to aid in complete combustion of the first and second types of coal.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/557,733 US20080105176A1 (en) | 2006-11-08 | 2006-11-08 | Staged-coal injection for boiler reliability and emissions reduction |
EP07112706A EP1983259A3 (en) | 2006-11-08 | 2007-07-18 | Staged coal injection for boiler reliability and emissions reduction |
CA002593918A CA2593918A1 (en) | 2006-11-08 | 2007-07-18 | Staged coal injection for boiler reliability and emissions reduction |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/557,733 US20080105176A1 (en) | 2006-11-08 | 2006-11-08 | Staged-coal injection for boiler reliability and emissions reduction |
Publications (1)
Publication Number | Publication Date |
---|---|
US20080105176A1 true US20080105176A1 (en) | 2008-05-08 |
Family
ID=39358638
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/557,733 Abandoned US20080105176A1 (en) | 2006-11-08 | 2006-11-08 | Staged-coal injection for boiler reliability and emissions reduction |
Country Status (3)
Country | Link |
---|---|
US (1) | US20080105176A1 (en) |
EP (1) | EP1983259A3 (en) |
CA (1) | CA2593918A1 (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL2001797C2 (en) * | 2008-07-14 | 2010-01-18 | Essent En Produktie B V | Method for burning a second solid fuel in combination with a first solid fuel. |
US20100095905A1 (en) * | 2008-10-16 | 2010-04-22 | Lochinvar Corporation | Gas Fired Modulating Water Heating Appliance With Dual Combustion Air Premix Blowers |
CN101963352A (en) * | 2010-10-25 | 2011-02-02 | 南京航空航天大学 | Double rotational flow powdered coal burner |
WO2012159509A1 (en) * | 2011-11-14 | 2012-11-29 | 上海锅炉厂有限公司 | Single fireball quadrangle direct flow burner for combustion of anthracite coal |
RU2474758C1 (en) * | 2011-10-10 | 2013-02-10 | Общество с ограниченной ответственностью "Политехэнерго" | Method to control temperature of gases at outlet of combustion chamber of swirling-type furnace and swirling-type furnace |
US8517720B2 (en) | 2008-10-16 | 2013-08-27 | Lochinvar, Llc | Integrated dual chamber burner |
US9097436B1 (en) | 2010-12-27 | 2015-08-04 | Lochinvar, Llc | Integrated dual chamber burner with remote communicating flame strip |
RU2582722C2 (en) * | 2013-08-05 | 2016-04-27 | Евгений Михайлович Пузырёв | Vortex furnace |
US9464805B2 (en) | 2013-01-16 | 2016-10-11 | Lochinvar, Llc | Modulating burner |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103486571A (en) * | 2013-09-18 | 2014-01-01 | 江苏太湖锅炉股份有限公司 | Double fuel boiler |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4480560A (en) * | 1983-12-09 | 1984-11-06 | International Coal Refining Company | Pneumatic conveying of pulverized solvent refined coal |
US5020479A (en) * | 1988-09-10 | 1991-06-04 | The Kansai Electronic Power Company Inc. | Watertube boiler and its method of combustion |
US5327726A (en) * | 1992-05-22 | 1994-07-12 | Foster Wheeler Energy Corporation | Staged furnaces for firing coal pyrolysis gas and char |
US5364421A (en) * | 1991-07-31 | 1994-11-15 | Ziegler Coal Holding Company | Coal blends having improved ash viscosity |
US6604474B2 (en) * | 2001-05-11 | 2003-08-12 | General Electric Company | Minimization of NOx emissions and carbon loss in solid fuel combustion |
US6699029B2 (en) * | 2001-01-11 | 2004-03-02 | Praxair Technology, Inc. | Oxygen enhanced switching to combustion of lower rank fuels |
US6889619B2 (en) * | 2001-11-16 | 2005-05-10 | Hitachi, Ltd. | Solid fuel burner, burning method using the same, combustion apparatus and method of operating the combustion apparatus |
US6981456B2 (en) * | 2003-11-18 | 2006-01-03 | General Electric Company | Mercury reduction system and method in combustion flue gas using staging |
US7381387B2 (en) * | 2003-08-14 | 2008-06-03 | General Electric Company | Mercury reduction system and method in combustion flue gas using coal blending |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4259911A (en) * | 1979-06-21 | 1981-04-07 | Combustion Engineering, Inc. | Fluidized bed boiler feed system |
US6325002B1 (en) * | 1999-02-03 | 2001-12-04 | Clearstack Combustion Corporation | Low nitrogen oxides emissions using three stages of fuel oxidation and in-situ furnace flue gas recirculation |
US6726888B2 (en) * | 2002-01-25 | 2004-04-27 | General Electric Company | Method to decrease emissions of nitrogen oxide and mercury |
US7514052B2 (en) * | 2004-01-06 | 2009-04-07 | General Electric Company | Method for removal of mercury emissions from coal combustion |
US7168947B2 (en) * | 2004-07-06 | 2007-01-30 | General Electric Company | Methods and systems for operating combustion systems |
-
2006
- 2006-11-08 US US11/557,733 patent/US20080105176A1/en not_active Abandoned
-
2007
- 2007-07-18 CA CA002593918A patent/CA2593918A1/en not_active Abandoned
- 2007-07-18 EP EP07112706A patent/EP1983259A3/en not_active Withdrawn
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4480560A (en) * | 1983-12-09 | 1984-11-06 | International Coal Refining Company | Pneumatic conveying of pulverized solvent refined coal |
US5020479A (en) * | 1988-09-10 | 1991-06-04 | The Kansai Electronic Power Company Inc. | Watertube boiler and its method of combustion |
US5364421A (en) * | 1991-07-31 | 1994-11-15 | Ziegler Coal Holding Company | Coal blends having improved ash viscosity |
US5327726A (en) * | 1992-05-22 | 1994-07-12 | Foster Wheeler Energy Corporation | Staged furnaces for firing coal pyrolysis gas and char |
US6699029B2 (en) * | 2001-01-11 | 2004-03-02 | Praxair Technology, Inc. | Oxygen enhanced switching to combustion of lower rank fuels |
US6604474B2 (en) * | 2001-05-11 | 2003-08-12 | General Electric Company | Minimization of NOx emissions and carbon loss in solid fuel combustion |
US6889619B2 (en) * | 2001-11-16 | 2005-05-10 | Hitachi, Ltd. | Solid fuel burner, burning method using the same, combustion apparatus and method of operating the combustion apparatus |
US7381387B2 (en) * | 2003-08-14 | 2008-06-03 | General Electric Company | Mercury reduction system and method in combustion flue gas using coal blending |
US6981456B2 (en) * | 2003-11-18 | 2006-01-03 | General Electric Company | Mercury reduction system and method in combustion flue gas using staging |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010008280A1 (en) * | 2008-07-14 | 2010-01-21 | Essent Energie Productie B.V. | Method for combusting a second solid fuel in combination with a first solid fuel |
NL2001797C2 (en) * | 2008-07-14 | 2010-01-18 | Essent En Produktie B V | Method for burning a second solid fuel in combination with a first solid fuel. |
US8517720B2 (en) | 2008-10-16 | 2013-08-27 | Lochinvar, Llc | Integrated dual chamber burner |
US20100095905A1 (en) * | 2008-10-16 | 2010-04-22 | Lochinvar Corporation | Gas Fired Modulating Water Heating Appliance With Dual Combustion Air Premix Blowers |
US8286594B2 (en) | 2008-10-16 | 2012-10-16 | Lochinvar, Llc | Gas fired modulating water heating appliance with dual combustion air premix blowers |
US8807092B2 (en) | 2008-10-16 | 2014-08-19 | Lochinvar, Llc | Gas fired modulating water heating appliance with dual combustion air premix blowers |
CN101963352A (en) * | 2010-10-25 | 2011-02-02 | 南京航空航天大学 | Double rotational flow powdered coal burner |
US9097436B1 (en) | 2010-12-27 | 2015-08-04 | Lochinvar, Llc | Integrated dual chamber burner with remote communicating flame strip |
RU2474758C1 (en) * | 2011-10-10 | 2013-02-10 | Общество с ограниченной ответственностью "Политехэнерго" | Method to control temperature of gases at outlet of combustion chamber of swirling-type furnace and swirling-type furnace |
WO2012159509A1 (en) * | 2011-11-14 | 2012-11-29 | 上海锅炉厂有限公司 | Single fireball quadrangle direct flow burner for combustion of anthracite coal |
US9464805B2 (en) | 2013-01-16 | 2016-10-11 | Lochinvar, Llc | Modulating burner |
US10208953B2 (en) | 2013-01-16 | 2019-02-19 | A. O. Smith Corporation | Modulating burner |
RU2582722C2 (en) * | 2013-08-05 | 2016-04-27 | Евгений Михайлович Пузырёв | Vortex furnace |
Also Published As
Publication number | Publication date |
---|---|
EP1983259A2 (en) | 2008-10-22 |
EP1983259A3 (en) | 2009-01-21 |
CA2593918A1 (en) | 2008-05-08 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20080105176A1 (en) | Staged-coal injection for boiler reliability and emissions reduction | |
US20190277494A1 (en) | Process for cogasifying and cofiring engineered fuel with coal | |
JP4969015B2 (en) | Solid fuel burner and combustion method using solid fuel burner | |
CA2487215C (en) | Solid fuel burner, solid fuel burner combustion method, combustion apparatus and combustion apparatus operation method | |
US6699029B2 (en) | Oxygen enhanced switching to combustion of lower rank fuels | |
CN103267279B (en) | Low-nitric-oxide direct-current pulverized coal combustor adaptive to meager coal boiler | |
KR20040028709A (en) | Oxygen enhanced low nox combustion | |
CN109990267B (en) | Low NO suitable for low-volatile fuel co-combustion of biomassxCombustion system | |
US20100275825A1 (en) | Modifying transport air to control nox | |
JP2540636B2 (en) | boiler | |
CN102269402A (en) | Method and system for realizing NOx discharge reduction and stable combustion of power station boiler | |
JP2003240227A (en) | Solid fuel burner and burning method thereof | |
CA2653861C (en) | Combustion systems and processes for burning fossil fuel with reduced nitrogen oxide emissions | |
US6968791B2 (en) | Oxygen-enriched co-firing of secondary fuels in slagging cyclone combustors | |
RU2348861C1 (en) | Swirling-type furnace for solid fuel ignition | |
JP2019086188A (en) | boiler | |
JP2009047390A (en) | Mixed combustion boiler for pulverized coal and natural gas, and its combustion method | |
US20140212825A1 (en) | Oxy-combustion coupled firing and recirculation system | |
JP2008039341A (en) | Coal combustion method and coal combustion device | |
DE KAMP et al. | The co-firing of pulverised bituminous coals with straw, waste paper and municipal sewage sludge | |
Goughnour | NOx reduction with the use of feedlot biomass as a reburn fuel | |
CN219199151U (en) | Arrangement structure of W-shaped flame boiler biomass particles and coal coupled combustion system | |
JP7081407B2 (en) | boiler | |
JP5800423B2 (en) | Burner and boiler equipped with it | |
KR101995156B1 (en) | Combustion apparatus and generation system including the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ELECTRIC POWER RESEARCH INSTITUTE, INC., CALIFORNI Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:FACCHIANO, ANTHONY;CHANG, RAMSAY;REEL/FRAME:018496/0403 Effective date: 20061018 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |