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WO2018150510A1 - Method for inhibiting slagging and coal-fired power generation system - Google Patents

Method for inhibiting slagging and coal-fired power generation system Download PDF

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Publication number
WO2018150510A1
WO2018150510A1 PCT/JP2017/005691 JP2017005691W WO2018150510A1 WO 2018150510 A1 WO2018150510 A1 WO 2018150510A1 JP 2017005691 W JP2017005691 W JP 2017005691W WO 2018150510 A1 WO2018150510 A1 WO 2018150510A1
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Prior art keywords
slagging
coal
inhibitor
pulverized coal
combustion
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PCT/JP2017/005691
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French (fr)
Japanese (ja)
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英嗣 清永
健治 引野
啓一郎 盛田
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中国電力株式会社
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Priority to JP2017549351A priority Critical patent/JP6304459B1/en
Priority to PCT/JP2017/005691 priority patent/WO2018150510A1/en
Publication of WO2018150510A1 publication Critical patent/WO2018150510A1/en

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    • 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

Definitions

  • the present invention relates to a slugging suppression method and a coal-fired power generation system.
  • ash melting point When an elution inhibitor made of a calcium-containing material is introduced into a combustion boiler, the melting temperature of coal ash (hereinafter also referred to as “ash melting point”) is lowered, so that slagging is likely to occur in the combustion boiler.
  • an object of the present invention is to provide a slagging suppression method and a coal thermal power generation system that can suppress the occurrence of slagging in a combustion boiler while suppressing the elution of trace elements from coal ash.
  • a pulverized coal machine that pulverizes coal to produce pulverized coal, and a combustion boiler that combusts the pulverized coal produced by the pulverized coal machine with primary air and secondary air supplied to the subsequent stage of the primary air;
  • a slagging suppression method in a coal-fired power generation system comprising: a slagging inhibitor for suppressing slagging in the combustion boiler, wherein a slagging inhibitor is disposed at 825 ° C. after coal combustion in the combustion boiler from 825 ° C.
  • Slagging suppression method for supplying to the region up to the melting point temperature.
  • a pulverized coal machine that pulverizes coal to produce pulverized coal, and a combustion boiler that combusts the pulverized coal produced by the pulverized coal machine with primary air and secondary air that is supplied after the primary air;
  • the slagging inhibitor that suppresses slagging in the combustion boiler is applied to a region from 825 ° C. to the coal ash melting point temperature after the combustion location of the pulverized coal in the combustion boiler.
  • a coal-fired power generation system including a slagging inhibitor supply unit for supplying.
  • the slagging inhibitor supply unit supplies the slagging inhibitor to a flow path for mixing a part of exhaust gas generated by combustion of pulverized coal with secondary air.
  • the slagging inhibitor supply unit supplies the slagging inhibitor to a flow path for mixing a part of exhaust gas generated by combustion of pulverized coal with secondary air.
  • the slagging inhibitor supply unit is downstream of a gas recirculation ventilator provided in a flow path for mixing part of the exhaust gas generated by the combustion of pulverized coal with secondary air.
  • the coal-fired power generation system according to any one of (8) to (14), which is supplied to the side.
  • the generation of slagging in the combustion boiler can be suppressed while suppressing the elution of trace elements from the coal ash.
  • FIG. 1 is a schematic configuration diagram showing a pulverized coal combustion facility 1 in a coal thermal power generation system.
  • the coal-fired power generation system includes a pulverized coal combustion facility 1 shown in FIG. 1, a steam turbine (not shown), a generator, and the like.
  • a pulverized coal combustion section 16 described later, heat generated during the combustion of the pulverized coal is converted into steam. When the steam turbine is rotated by this steam, power is generated by the generator.
  • nitrogen oxide (NOx), soot, sulfur oxide (SOx), etc. generated during the combustion of the pulverized coal are removed by a denitration device 181, a dust collector 182 and a desulfurization device (not shown) in the subsequent stage. Discharged from the chimney.
  • NOx nitrogen oxide
  • SOx sulfur oxide
  • the pulverized coal combustion facility 1 includes a coal supply unit 12, a pulverized coal generation unit 14, a pulverized coal combustion unit (combustion boiler) 16, a coal ash treatment unit 18, and a slagging inhibitor supply unit. 20.
  • the coal supply unit 12 supplies coal to the pulverized coal generation unit 14.
  • the pulverized coal generation unit 14 converts the coal supplied from the coal supply unit 12 to pulverized coal.
  • the pulverized coal combustion unit 16 burns pulverized coal.
  • the coal ash processing unit 18 processes coal ash generated by the combustion of pulverized coal.
  • the slagging inhibitor supply unit 20 supplies the slagging inhibitor to the pulverized coal combustion unit 16.
  • the coal supply unit 12 includes a coal bunker 121 and a coal feeder 122.
  • the coal bunker 121 stores coal to be supplied to the coal feeder 122.
  • the coal feeder 122 continuously supplies the coal supplied from the coal bunker 121 to a pulverized coal machine 141 (described later).
  • the coal feeder 122 includes a device (not shown) that adjusts the amount of coal supplied.
  • the coal feeder 122 can adjust the amount of coal supplied to the pulverized coal machine 141.
  • the coal supply unit 12 includes a coal gate (not shown) at the boundary between the coal bunker 121 and the coal feeder 122. The coal gate prevents air from the coal feeder 122 from flowing into the coal bunker 121.
  • the pulverized coal generation unit 14 includes a pulverized coal machine (mill) 141 and an air supply unit 142 that supplies air to the pulverized coal machine 141.
  • the pulverized coal machine 141 pulverizes the coal supplied from the coal feeder 122 through the coal supply pipe to a fine particle size to produce pulverized coal.
  • the pulverized coal machine 141 mixes the pulverized coal with the air supplied from the air supply unit 142. Since the pulverized coal is preheated and dried by mixing with air, it easily burns in the furnace 161 (described later).
  • the pulverized coal is supplied to the pulverized coal combustion unit 16 by blowing air.
  • the types of the pulverized coal machine 141 include a roller mill, a tube mill, a ball mill, a beater mill, an impeller mill, and the like, but are not limited to these and may be any mill used in pulverized coal combustion.
  • Pulverized coal combustion unit 16 includes a furnace 161, a heater 162 (heat exchange unit), and an air supply unit 163.
  • the furnace 161 combusts the pulverized coal supplied from the pulverized coal machine 141 together with the air and exhaust gas supplied from the air supply unit 163.
  • the heater 162 heat exchange unit
  • the air supply unit 163 supplies combustion air (primary air and secondary air) to the furnace 161.
  • coal ash (coal combustion residue) is generated. Due to the generation of coal ash, the phenomenon called slagging and fouling described above occurs.
  • Slagging is a phenomenon in which molten ash particles adhere to and accumulate near the burner, boiler suspension pipe, furnace wall, water-cooled wall pipe, and the like, causing problems such as closing of the gas flow path.
  • fouling is a phenomenon in which the sulfuric acid compound that has become vapor adheres to the surface of the heat transfer tube, and an adhesion layer of combustion ash is formed thereon, which causes problems such as corrosion of the heat transfer tube. Slagging and fouling are likely to occur when the ash melting point is lowered.
  • the pulverized coal combustion unit 16 supplies the air necessary for complete combustion of the pulverized coal in two places, ie, a burner 61 and an air supply port 62 provided in the upper part of the burner. It is composed of a stage combustion method.
  • the burner 61 is supplied with pulverized coal together with primary air and exhaust gas. Secondary air is supplied to the air supply port 62 together with the exhaust gas.
  • the exhaust gas supplied to the burner 61 and the air supply port 62 is obtained by recirculating part of the exhaust gas discharged from the pulverized coal combustion unit 16.
  • the pulverized coal combustion unit 16 when the air (oxygen) supplied to the burner 61 is large, the combustion temperature becomes high, and a large amount of nitrogen oxide (NOx) is generated together with coal ash. Therefore, by adjusting the distribution amount of the primary air and the exhaust gas supplied to the burner 61 and burning the pulverized coal in a state where oxygen is insufficient, the generation of nitrogen oxides can be suppressed. Further, by adjusting the distribution amount of the secondary air and exhaust gas supplied to the air supply port 62 and increasing oxygen, the combustion reaction can be further promoted between the air supply port 62 and the furnace outlet.
  • the air (oxygen) supplied to the burner 61 when the air (oxygen) supplied to the burner 61 is large, the combustion temperature becomes high, and a large amount of nitrogen oxide (NOx) is generated together with coal ash. Therefore, by adjusting the distribution amount of the primary air and the exhaust gas supplied to the burner 61 and burning the pulverized coal in a state where oxygen is insufficient, the generation of nitrogen oxides can be suppress
  • coal ash is generated. Further, together with coal ash, exhaust gases such as sulfur oxide (SOx) such as sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ) and nitrogen oxide (NOx) are generated. These coal ash and exhaust gas are discharged to the coal ash treatment unit 18.
  • SOx sulfur oxide
  • SO 2 sulfur dioxide
  • SO 3 sulfur trioxide
  • NOx nitrogen oxide
  • the coal ash treatment unit 18 includes a denitration device 181, a dust collector 182, and a coal ash collection silo 183.
  • the denitration device 181 removes nitrogen oxides in the exhaust gas discharged from the pulverized coal combustion unit 16.
  • ammonia gas is injected as a reducing agent into a relatively high temperature (300 to 400 ° C.) exhaust gas, and nitrogen oxides in the exhaust gas are decomposed into harmless nitrogen and water vapor by the action of the denitration catalyst.
  • a so-called dry ammonia catalytic reduction method is preferably used.
  • the dust collector 182 collects coal ash (dust) in the exhaust gas with an electrode.
  • the dust collectors 182 are preferably provided in a plurality of stages.
  • Coal ash collected by the dust collector 182 is temporarily stored in the coal ash recovery silo 183.
  • the exhaust gas from which the coal ash has been removed is discharged from the chimney after the sulfur oxide is removed by a desulfurization apparatus (not shown).
  • the coal ash collection silo 183 temporarily stores the coal ash collected by the dust collector 182.
  • the slagging inhibitor supply unit 20 supplies the slagging inhibitor to the pulverized coal combustion unit 16.
  • the slagging inhibitor supply unit 20 supplies the slagging inhibitor to the region of the furnace 161 from 825 ° C. to the coal ash melting point temperature.
  • the “coal ash melting point temperature” is generally a temperature between 1220 ° C. and 1600 ° C., although it varies depending on the coal type of coal.
  • the region where the slagging inhibitor is normally supplied is the narrowest region depending on the coal type of coal, the region from 825 ° C to 1220 ° C of the furnace 161, and the widest region of 825 ° C of the furnace 161. To 1600 ° C. The position where the slagging inhibitor is supplied will be described later.
  • the slagging inhibitor is an alkaline earth metal compound, for example, a calcium-containing material such as calcium carbonate (CaCO 3 ). In this embodiment, an example in which limestone is used as a slagging inhibitor will be described.
  • the slagging inhibitor is preferably granular or powdery.
  • the average particle size of the slagging inhibitor is preferably 10 ⁇ m to 100 ⁇ m, and more preferably 10 ⁇ m to 70 ⁇ m.
  • the slagging suppression method according to the present invention includes a pulverized coal machine that pulverizes coal to produce pulverized coal, and secondary air that supplies the pulverized coal produced by the pulverized coal machine to primary air and a subsequent stage of the primary air. And a slagging suppression method in a coal-fired power generation system provided with a combustion boiler, wherein a slagging inhibitor for suppressing slagging in the combustion boiler is a region from 825 ° C. to a coal ash melting point temperature in the combustion boiler. It is characterized by supplying to.
  • the slugging suppression method according to the present invention will be described using the pulverized coal combustion facility 1 described above.
  • the slagging suppression method includes a coal supply step S10 for supplying coal, a pulverized coal generation step S20 for pulverizing the supplied coal to generate pulverized coal, and a pulverized coal combustion step S30 for burning the pulverized coal. And a coal ash treatment step S40 for treating coal ash generated by the combustion of pulverized coal, and a slagging inhibitor supply step S50 for supplying a slagging inhibitor.
  • each process from coal supply process S10 to coal ash treatment process S40 is performed in coal supply part 12, pulverized coal generation part 14, pulverized coal combustion part 16, and coal ash treatment part 18 of pulverized coal combustion facility 1, respectively. Is called.
  • slagging inhibitor supply process S50 is performed by pulverized coal combustion process S30 mentioned above.
  • ⁇ Coal supply process S10> First, in the coal supply step S ⁇ b> 10, the coal stored in the coal bunker 121 is supplied to the pulverized coal machine 141 by the coal feeder 122.
  • the coal supplied to the pulverized coal machine 141 is specifically bituminous coal, subbituminous coal, lignite, etc., but is not limited to these coals, and may be any coal that can perform pulverized coal combustion. .
  • pulverized coal production process S20> the coal supplied from the coal feeder 122 is pulverized by the pulverized coal machine 141 to produce pulverized coal.
  • the produced pulverized coal is supplied to the furnace 161.
  • the average particle size of the pulverized coal may be in the particle size range generally used in pulverized coal combustion, and is generally a pulverization degree of 74 ⁇ m or less and 80 wt% or more.
  • the pulverized coal generated by the pulverized coal machine 141 is burned by the furnace 161.
  • the pulverized coal burns in the vicinity of a burner zone 161a (described later) in the furnace 161, and the furnace temperature at this time reaches 1300 ° C to 1500 ° C.
  • the coal ash produced by the combustion rises along the direction of the arrow and is sent to the denitration device 181 (coal ash treatment unit 18) together with the exhaust gas.
  • the furnace temperature in the vicinity of the upper part of the burner zone 161a is from 825 ° C. to the coal ash melting temperature.
  • a slagging inhibitor supply step S50 which is a step of supplying a slagging inhibitor, which is a feature of the present invention, is performed in a pulverized coal combustion step S30 as shown in FIG. 1 (S51 in FIG. 1).
  • a pulverized coal combustion step S30 as shown in FIG. 1 (S51 in FIG. 1).
  • the supply of the slagging inhibitor performed in the pulverized coal combustion step S30 will be described.
  • FIG. 2 is a diagram showing a configuration of the furnace 161 and its surroundings in the pulverized coal combustion facility 1.
  • a burner 61 is provided below the furnace 161.
  • the burner 61 is supplied with pulverized coal 200 supplied from the pulverized coal machine 141 (see FIG. 1), primary air 201 supplied from the air supply unit 163, and recirculated exhaust gas 203.
  • the pulverized coal 200 burns in the furnace 161 mainly in the burner zone 161a.
  • An air supply port 62 is provided in the upper part of the burner 61.
  • the air supply port 62 is supplied with the secondary air 202 supplied from the air supply machine 163 and the recirculated exhaust gas 203.
  • the combustion reaction of the pulverized coal that has not been burned in the vicinity of the burner zone 161a is promoted, and the pulverized coal can be completely burned.
  • the exhaust gas 203 (combustion gas) generated by the combustion of pulverized coal is discharged together with the coal ash from the furnace outlet 161b to the subsequent denitration device 181 (the coal ash treatment unit 18).
  • heat exchange units such as a superheater, a reheater, and a economizer are provided near the upper portion of the burner 61 and the furnace outlet 161b.
  • the pulverized coal combustion unit 16 recirculates a part of the exhaust gas 203 and supplies it to the burner 61 and the air supply port 62 as a gas recirculation ventilator 63, a dust collector 64,
  • the exhaust gas passage 100 is provided.
  • the gas recirculation ventilator 63 is a blower fan that takes in a part of the exhaust gas 203 discharged from the furnace outlet 161 b and sends it to the burner 61 and the air supply port 62.
  • the dust collector 64 is a device that collects coal ash (dust) contained in the exhaust gas 203. As the dust collector 64, for example, a mechanical dust collector can be used.
  • the exhaust gas passage 100 is an air duct that guides part of the exhaust gas 203 discharged from the furnace outlet 161 b to the burner 61 and the air supply port 62.
  • the exhaust gas passage 100 includes a first exhaust gas passage 110, a second exhaust gas passage 120, and a third exhaust gas passage 130.
  • the first exhaust gas passage 110 is a passage for taking out the exhaust gas 203 from the furnace outlet 161b side.
  • a gas recirculation ventilator 63 and a dust collector 64 are connected to the first exhaust gas passage 110.
  • the upstream end of the first exhaust gas passage 110 is connected to the furnace outlet 161b side.
  • the downstream end of the first exhaust gas passage 110 is connected to the exhaust gas inlet side of the dust collector 64.
  • the second exhaust gas passage 120 is a passage that guides the exhaust gas 203 to the burner 61.
  • the upstream end of the second exhaust gas passage 120 is connected to the exhaust gas outlet side of the dust collector 64.
  • the downstream end portion of the second exhaust gas passage 120 is connected to an exhaust gas introduction portion (not shown) of the burner 61.
  • the third exhaust gas passage 130 is a passage that guides the exhaust gas 203 to the air supply port 62.
  • the upstream end of the third exhaust gas passage 130 is connected to the exhaust gas outlet side of the dust collector 64 together with the upstream end of the second exhaust gas passage 120 described above.
  • the downstream end of the third exhaust gas passage 130 is connected to an exhaust gas introduction part (not shown) of the air supply port 62.
  • a slagging inhibitor passage 140 is connected to the third exhaust gas passage 130.
  • the slagging inhibitor passage 140 is a passage for supplying the slagging inhibitor 204 from the slagging inhibitor supply unit 20 to the third exhaust gas passage 130.
  • the slagging inhibitor 204 is intermittently supplied between the dust collector 64 and the air supply port 62 at a predetermined time interval.
  • the exhaust gas passage 100 including the third exhaust gas passage 130 functions as a flow channel for mixing a part of the exhaust gas 203 with the secondary air 202.
  • a blower fan that pushes the exhaust gas 203 downstream may be provided in the middle of the second exhaust gas passage 120 and the third exhaust gas passage 130.
  • a part of the exhaust gas 203 taken out from the furnace outlet 161 b side is guided to the dust collector 64 through the gas recirculation ventilator 63 by the first exhaust gas passage 110.
  • the exhaust gas 203 branches into the second exhaust gas passage 120 and the third exhaust gas passage 130 on the exhaust gas outlet side of the dust collector 64 and is guided to the burner 61 and the air supply port 62, respectively.
  • the exhaust gas 203 guided to the burner 61 is supplied from the burner 61 to the furnace 161 together with the pulverized coal 200 and the primary air 201.
  • the exhaust gas 203 guided to the air supply port 62 is supplied to the furnace 161 from the air supply port 62 together with the secondary air 202 and the slagging inhibitor 204.
  • the mechanism in which slagging is suppressed by introducing the slagging inhibitor 204 from the air supply port 62 into the furnace 161 in the region from 825 ° C. to the coal ash melting point temperature is as follows. Conceivable.
  • the slagging inhibitor 204 When calcium carbonate (CaCO 3 ), which is the slagging inhibitor 204, is supplied to the furnace 161 together with the secondary air 202, the slagging inhibitor 204 is introduced into the vicinity of the upper portion of the burner zone 161a from the air supply port 62. Since the furnace temperature in the vicinity is from 825 ° C. to the coal ash melting point temperature, CaCO 3 is decomposed into CaO and CO 2 . Although the decomposed CaO has a low melting point as a compound, the decomposed CaO has a melting point of about 2570 ° C., and therefore reacts with coal ash in the vicinity of the upper part of the burner zone 161a where the temperature is lower than that of the burner zone 161a. It becomes difficult. As described above, when the slagging inhibitor 204 is supplied from the air supply port 62 to the vicinity of the upper portion of the burner zone 161a, a large amount of CaO is present alone, so that the ash melting point is estimated to increase
  • the slagging inhibitor 204 intermittently at predetermined time intervals, the slagging generated in the vicinity of the burner, the boiler suspension pipe, the furnace wall, the water-cooled wall pipe, etc., as shown in FIG. A sandwich structure of a low melting point compound such as Fe, Ca, Si, Al, and Mg and a mass of CaO is obtained. As a result, slagging is easily peeled off at the interface between the low melting point compound and the CaO lump, thereby preventing the slagging from becoming enormous.
  • a low melting point compound such as Fe, Ca, Si, Al, and Mg and a mass of CaO
  • the ash melting point of the ash produced by separately adding in the vicinity was measured.
  • the amount of calcium carbonate added separately at around 950 ° C. was added so as to be the same amount (CaO: 3.1%) in terms of calcium in ash when “A charcoal and B charcoal” were burned. .
  • the measurement results are shown in Table 1.
  • the ash melting point of the ash produced by exclusively burning “A charcoal” was 1311 to 1364 ° C.
  • the ash melting point of the ash produced by burning only “B charcoal” was 1234 to 1301 ° C.
  • the ash melting point of the ash produced by burning “A coal + B coal” was 1235 to 1301 ° C., which was lower than the ash melting point of the ash produced by burning only “A coal”.
  • the ash melting point of the ash produced by burning “A charcoal” and adding calcium carbonate separately at around 950 ° C. is higher than the ash melting point of the ash produced by burning only “A charcoal”, It was 1323 to 1387 ° C.
  • the mechanism is considered as follows.
  • the decomposed CaO reacts with selenium oxide, arsenic trioxide, boron oxide, and the like, which are trace elements contained in coal ash, and is insoluble insoluble compounds such as calcium selenite, calcium arsenate, and calcium borate, respectively. Is generated. That is, trace elements are chemically captured by CaO to produce a hardly soluble insoluble compound.
  • the slagging inhibitor 204 into the furnace 161 in the region from 825 ° C. to the coal ash melting point, which is after the pulverized coal combustion location, the behavior of the trace elements contained in the coal ash is controlled, Elution of more trace elements can be suppressed.
  • the slagging inhibitor 204 is supplied to a region from 825 ° C. to the coal ash melting point temperature in the furnace 161, after the combustion location of the pulverized coal. Therefore, generation
  • the pulverized coal combustion facility 1 of the present embodiment can sufficiently suppress the elution of trace elements even for a coal type having a high content of trace elements, which has been difficult in the past, and therefore greatly increases the applicable coal types. be able to. Thereby, for example, the fuel cost cost can be reduced by using an inexpensive coal type having a high trace element content.
  • the present invention is not limited to this and may be supplied continuously.
  • the present invention is not limited to this and may be supplied continuously.
  • CaO islands are generated in places during the slagging mainly composed of a low melting point compound.
  • slagging since there is a boundary surface between CaO in a spherical shape with a small particle size and the low melting point compound, slagging has a structure that tends to collapse into a granular shape, thus preventing enlargement of slagging. It becomes possible.
  • the slagging inhibitor is supplied to the third exhaust gas passage 130 , but the present invention is not limited to this. If the slagging inhibitor can be supplied to the region from 825 ° C. to the coal ash melting point temperature in the furnace 161 after the pulverized coal combustion location, the position for supplying the slagging inhibitor can be appropriately selected.
  • the slagging inhibitor may be supplied from between the gas recirculation ventilator 63 and the dust collector 64 (the first exhaust gas passage 110).
  • the present invention is not limited to this. Moreover, you may supply a slagging inhibitor to the furnace 161 with a vapor

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Abstract

The present invention provides a method for inhibiting slagging and a coal-fired power generation system that are capable of inhibiting the generation of slagging inside a combustion boiler while inhibiting the elution of trace elements from coal ash. This method for inhibiting slagging for a coal-fired power generation system, which is provided with a coal pulverizer 141 for pulverizing coal to manufacture pulverized coal, and a combustion boiler 16 that uses primary air and secondary air supplied at a later stage than the primary air to burn the pulverized coal manufactured by the coal pulverizer 141, includes supplying a slagging inhibitor for inhibiting slagging in the combustion boiler 16 to a region from 825°C to the coal melting point temperature inside the combustion boiler 16 and at a later stage than the combustion location of the pulverized coal.

Description

スラッギング抑制方法及び石炭火力発電システムSlagging suppression method and coal-fired power generation system
　本発明は、スラッギング抑制方法及び石炭火力発電システムに関する。 The present invention relates to a slugging suppression method and a coal-fired power generation system.
　発電所等の燃焼ボイラにおいて、石灰石等のカルシウム含有物を溶出抑制剤として石炭に添加することにより、石炭に含まれるフッ素、ホウ素、セレン、ヒ素、六価クロム等の微量元素（以下、「微量元素」ともいう）を燃焼残渣である石炭灰から溶出しにくくする微量元素の溶出抑制方法が提案されている（例えば、特許文献１参照）。 In combustion boilers such as power plants, trace elements such as fluorine, boron, selenium, arsenic, hexavalent chromium, etc. contained in coal are added by adding calcium-containing substances such as limestone to coal as an elution inhibitor. There has been proposed a method for suppressing the elution of trace elements that makes it difficult to elute elemental) from coal ash, which is a combustion residue (see, for example, Patent Document 1).
特開２００８－１７０１０９号公報JP 2008-170109 A
　燃焼ボイラにカルシウム含有物からなる溶出抑制剤を投入すると、石炭灰の溶融温度（以下、「灰融点」ともいう）が低くなるため、燃焼ボイラ内においてスラッギングが発生しやすくなる。 When an elution inhibitor made of a calcium-containing material is introduced into a combustion boiler, the melting temperature of coal ash (hereinafter also referred to as “ash melting point”) is lowered, so that slagging is likely to occur in the combustion boiler.
　従って、本発明は、石炭灰からの微量元素の溶出を抑制しつつ、燃焼ボイラ内におけるスラッギングの発生を抑制できるスラッギング抑制方法及び石炭火力発電システムを提供することを目的とする。 Therefore, an object of the present invention is to provide a slagging suppression method and a coal thermal power generation system that can suppress the occurrence of slagging in a combustion boiler while suppressing the elution of trace elements from coal ash.
（１）石炭を粉砕して微粉炭を製造する微粉炭機と、前記微粉炭機で製造された微粉炭を一次空気及び前記一次空気の後段に供給される二次空気により燃焼させる燃焼ボイラと、を備えた石炭火力発電システムにおけるスラッギング抑制方法であって、前記燃焼ボイラにおけるスラッギングを抑制するスラッギング抑制剤を、前記燃焼ボイラ中、前記微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に供給するスラッギング抑制方法。 (1) A pulverized coal machine that pulverizes coal to produce pulverized coal, and a combustion boiler that combusts the pulverized coal produced by the pulverized coal machine with primary air and secondary air supplied to the subsequent stage of the primary air; A slagging suppression method in a coal-fired power generation system comprising: a slagging inhibitor for suppressing slagging in the combustion boiler, wherein a slagging inhibitor is disposed at 825 ° C. after coal combustion in the combustion boiler from 825 ° C. Slagging suppression method for supplying to the region up to the melting point temperature.
（２）前記スラッギング抑制剤は、アルカリ土類金属の化合物を含む、（１）に記載のスラッギング抑制方法。 (2) The slagging inhibiting method according to (1), wherein the slagging inhibiting agent comprises an alkaline earth metal compound.
（３）前記スラッギング抑制剤は、炭酸カルシウム（ＣａＣＯ３）を含む、（１）又は（２）に記載のスラッギング抑制方法。 (3) The slagging suppression method according to (1) or (2), wherein the slagging inhibitor includes calcium carbonate (CaCO 3 ).
（４）前記スラッギング抑制剤を、前記二次空気と共に前記燃焼ボイラに供給する、（１）～（３）のいずれかに記載のスラッギング抑制方法。 (4) The slagging suppression method according to any one of (1) to (3), wherein the slagging inhibitor is supplied to the combustion boiler together with the secondary air.
（５）前記スラッギング抑制剤を、微粉炭の燃焼により発生した排ガスの一部を二次空気と混合させるための流路に供給する、（１）～（４）のいずれかに記載のスラッギング抑制方法。 (5) The slagging suppression agent according to any one of (1) to (4), wherein the slagging suppression agent is supplied to a flow path for mixing a part of exhaust gas generated by the combustion of pulverized coal with secondary air. Method.
（６）前記スラッギング抑制剤を、間欠的に所定の時間間隔で供給する、（１）～（５）のいずれか１に記載のスラッギング抑制方法。 (6) The slagging suppression method according to any one of (1) to (5), wherein the slagging inhibitor is intermittently supplied at predetermined time intervals.
（７）前記スラッギング抑制剤を、連続的に供給する、（１）～（５）のいずれか１に記載のスラッギング抑制方法。 (7) The slagging suppression method according to any one of (1) to (5), wherein the slagging inhibitor is continuously supplied.
（８）石炭を粉砕して微粉炭を製造する微粉炭機と、前記微粉炭機で製造された微粉炭を一次空気及び前記一次空気の後段で供給される二次空気により燃焼させる燃焼ボイラと、を備えた石炭火力発電システムにおいて、前記燃焼ボイラにおけるスラッギングを抑制するスラッギング抑制剤を、前記燃焼ボイラ中、前記微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に供給するスラッギング抑制剤供給部を備える石炭火力発電システム。 (8) A pulverized coal machine that pulverizes coal to produce pulverized coal, and a combustion boiler that combusts the pulverized coal produced by the pulverized coal machine with primary air and secondary air that is supplied after the primary air; The slagging inhibitor that suppresses slagging in the combustion boiler is applied to a region from 825 ° C. to the coal ash melting point temperature after the combustion location of the pulverized coal in the combustion boiler. A coal-fired power generation system including a slagging inhibitor supply unit for supplying.
（９）前記スラッギング抑制剤は、アルカリ土類金属の化合物を含む、（８）に記載の石炭火力発電システム。 (9) The coal-fired power generation system according to (8), wherein the slagging inhibitor includes an alkaline earth metal compound.
（１０）前記スラッギング抑制剤は、炭酸カルシウム（ＣａＣＯ３）を含む、（８）又は（９）に記載の石炭火力発電システム。 (10) The coal-fired power generation system according to (8) or (9), wherein the slagging inhibitor includes calcium carbonate (CaCO 3 ).
（１１）前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、前記二次空気と共に前記燃焼ボイラに供給する、（８）～（１０）のいずれかに記載の石炭火力発電システム。 (11) The coal thermal power generation system according to any one of (8) to (10), wherein the slagging inhibitor supply unit supplies the slagging inhibitor to the combustion boiler together with the secondary air.
（１２）前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、微粉炭の燃焼により発生した排ガスの一部を二次空気と混合させるための流路に供給する、（８）～（１１）のいずれかに記載の石炭火力発電システム。 (12) The slagging inhibitor supply unit supplies the slagging inhibitor to a flow path for mixing a part of exhaust gas generated by combustion of pulverized coal with secondary air. (8) to (11) A coal-fired power generation system according to any one of the above.
（１３）前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、間欠的に供給する、（８）～（１２）のいずれかに記載の石炭火力発電システム。 (13) The coal-fired power generation system according to any one of (8) to (12), wherein the slagging inhibitor supply unit supplies the slagging inhibitor intermittently.
（１４）前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、連続的に供給する、（８）～（１２）のいずれかに記載の石炭火力発電システム。 (14) The coal thermal power generation system according to any one of (8) to (12), wherein the slagging inhibitor supply unit continuously supplies the slagging inhibitor.
（１５）前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、微粉炭の燃焼により発生した排ガスの一部を二次空気と混合させるための流路に設けられたガス再循環通風機の下流側に供給する、（８）～（１４）のいずれかに記載の石炭火力発電システム。 (15) The slagging inhibitor supply unit is downstream of a gas recirculation ventilator provided in a flow path for mixing part of the exhaust gas generated by the combustion of pulverized coal with secondary air. The coal-fired power generation system according to any one of (8) to (14), which is supplied to the side.
　本発明によれば、石炭灰からの微量元素の溶出を抑制しつつ、燃焼ボイラ内におけるスラッギングの発生を抑制できる。 According to the present invention, the generation of slagging in the combustion boiler can be suppressed while suppressing the elution of trace elements from the coal ash.
石炭火力発電システムにおける微粉炭燃焼施設１を示す概略構成図である。It is a schematic block diagram which shows the pulverized coal combustion facility 1 in a coal thermal power generation system. 微粉炭燃焼施設１における火炉１６１とその周辺の構成を示す図である。It is a figure which shows the structure of the furnace 161 in the pulverized coal combustion facility 1, and its periphery. ＣａＯと低融点化合物とからなるスラッギングの構造を示す図である。It is a figure which shows the structure of the slagging which consists of CaO and a low melting-point compound. ＣａＯと低融点化合物とからなるスラッギングの構造を示す図である。It is a figure which shows the structure of the slagging which consists of CaO and a low melting-point compound.
　以下、本発明の実施形態について、図面を参照しながら説明する。なお、本明細書に添付した図面では、各部の形状、配置等を模式的に示している。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings attached to this specification, the shape, arrangement, and the like of each part are schematically shown.
　＜Ａ：石炭火力発電システムにおける微粉炭燃焼施設１の構成＞
　図１は、石炭火力発電システムにおける微粉炭燃焼施設１を示す概略構成図である。
　石炭火力発電システムは、図１に示す微粉炭燃焼施設１のほか、不図示の蒸気タービン、発電機等を備える。後述する微粉炭燃焼部１６において、微粉炭の燃焼時に発生した熱は、蒸気に変換される。この蒸気により蒸気タービンが回されることにより、発電機で発電が行われる。微粉炭燃焼部１６において、微粉炭の燃焼時に発生する窒素酸化物（ＮＯｘ）、煤塵、硫黄酸化物（ＳＯｘ）等は、後段の脱硝装置１８１、集塵機１８２及び脱硫装置（不図示）で除去され、煙突から排出される。 <A: Configuration of pulverized coal combustion facility 1 in a coal-fired power generation system>
FIG. 1 is a schematic configuration diagram showing a pulverized coal combustion facility 1 in a coal thermal power generation system.
The coal-fired power generation system includes a pulverized coal combustion facility 1 shown in FIG. 1, a steam turbine (not shown), a generator, and the like. In the pulverized coal combustion section 16 described later, heat generated during the combustion of the pulverized coal is converted into steam. When the steam turbine is rotated by this steam, power is generated by the generator. In the pulverized coal combustion section 16, nitrogen oxide (NOx), soot, sulfur oxide (SOx), etc. generated during the combustion of the pulverized coal are removed by a denitration device 181, a dust collector 182 and a desulfurization device (not shown) in the subsequent stage. Discharged from the chimney.
　図１に示すように、微粉炭燃焼施設１は、石炭供給部１２と、微粉炭生成部１４と、微粉炭燃焼部（燃焼ボイラ）１６と、石炭灰処理部１８と、スラッギング抑制剤供給部２０と、を備える。 As shown in FIG. 1, the pulverized coal combustion facility 1 includes a coal supply unit 12, a pulverized coal generation unit 14, a pulverized coal combustion unit (combustion boiler) 16, a coal ash treatment unit 18, and a slagging inhibitor supply unit. 20.
　石炭供給部１２は、微粉炭生成部１４へ石炭を供給する。微粉炭生成部１４は、石炭供給部１２から供給された石炭を微粉炭にする。微粉炭燃焼部１６は、微粉炭を燃焼させる。石炭灰処理部１８は、微粉炭の燃焼により生成された石炭灰を処理する。スラッギング抑制剤供給部２０は、スラッギング抑制剤を微粉炭燃焼部１６へ供給する。 The coal supply unit 12 supplies coal to the pulverized coal generation unit 14. The pulverized coal generation unit 14 converts the coal supplied from the coal supply unit 12 to pulverized coal. The pulverized coal combustion unit 16 burns pulverized coal. The coal ash processing unit 18 processes coal ash generated by the combustion of pulverized coal. The slagging inhibitor supply unit 20 supplies the slagging inhibitor to the pulverized coal combustion unit 16.
　＜Ａ－１：石炭供給部１２＞
　石炭供給部１２は、石炭バンカ１２１と、給炭機１２２と、を備える。石炭バンカ１２１は、給炭機１２２へ供給する石炭を貯蔵する。給炭機１２２は、石炭バンカ１２１から供給された石炭を連続して微粉炭機１４１（後述）へ供給する。給炭機１２２は、石炭の供給量を調整する装置（不図示）を備える。給炭機１２２は、微粉炭機１４１に供給される石炭量を調整できる。また、石炭供給部１２は、石炭バンカ１２１と給炭機１２２との境界に石炭ゲート（不図示）を備える。この石炭ゲートは、給炭機１２２からの空気が石炭バンカ１２１へ流入することを防止する。 <A-1: Coal supply unit 12>
The coal supply unit 12 includes a coal bunker 121 and a coal feeder 122. The coal bunker 121 stores coal to be supplied to the coal feeder 122. The coal feeder 122 continuously supplies the coal supplied from the coal bunker 121 to a pulverized coal machine 141 (described later). The coal feeder 122 includes a device (not shown) that adjusts the amount of coal supplied. The coal feeder 122 can adjust the amount of coal supplied to the pulverized coal machine 141. The coal supply unit 12 includes a coal gate (not shown) at the boundary between the coal bunker 121 and the coal feeder 122. The coal gate prevents air from the coal feeder 122 from flowing into the coal bunker 121.
　＜Ａ－２：微粉炭生成部１４＞
　微粉炭生成部１４は、微粉炭機（ミル）１４１と、微粉炭機１４１に空気を供給する空気供給機１４２と、を備える。 <A-2: Pulverized coal generation unit 14>
The pulverized coal generation unit 14 includes a pulverized coal machine (mill) 141 and an air supply unit 142 that supplies air to the pulverized coal machine 141.
　微粉炭機１４１は、給炭機１２２から給炭管を介して供給された石炭を、微細な粒度に粉砕して微粉炭を製造する。また、微粉炭機１４１は、微粉炭と、空気供給機１４２から供給された空気とを混合する。微粉炭は、空気との混合により、予熱及び乾燥されるため、火炉１６１（後述）において容易に燃焼する。微粉炭は、エアーの吹き付けにより、微粉炭燃焼部１６へ供給される。 The pulverized coal machine 141 pulverizes the coal supplied from the coal feeder 122 through the coal supply pipe to a fine particle size to produce pulverized coal. The pulverized coal machine 141 mixes the pulverized coal with the air supplied from the air supply unit 142. Since the pulverized coal is preheated and dried by mixing with air, it easily burns in the furnace 161 (described later). The pulverized coal is supplied to the pulverized coal combustion unit 16 by blowing air.
　微粉炭機１４１の種類としては、ローラミル、チューブミル、ボールミル、ビータミル、インペラーミル等が挙げられるが、これらに限定されるものではなく微粉炭燃焼で用いられるミルであればよい。 The types of the pulverized coal machine 141 include a roller mill, a tube mill, a ball mill, a beater mill, an impeller mill, and the like, but are not limited to these and may be any mill used in pulverized coal combustion.
　＜Ａ－３：微粉炭燃焼部１６＞
　微粉炭燃焼部１６は、火炉１６１と、加熱機１６２（熱交換ユニット）と、空気供給機１６３と、を備える。 <A-3: Pulverized coal combustion unit 16>
The pulverized coal combustion unit 16 includes a furnace 161, a heater 162 (heat exchange unit), and an air supply unit 163.
　火炉１６１は、微粉炭機１４１から供給された微粉炭を、空気供給機１６３から供給された空気及び排ガスと共に燃焼させる。加熱機１６２（熱交換ユニット）は、火炉１６１に送られる空気と排ガスとの間で熱交換を行い、空気を予熱する。空気供給機１６３は、火炉１６１に燃焼用の空気（一次空気及び二次空気）を供給する。 The furnace 161 combusts the pulverized coal supplied from the pulverized coal machine 141 together with the air and exhaust gas supplied from the air supply unit 163. The heater 162 (heat exchange unit) preheats the air by exchanging heat between the air sent to the furnace 161 and the exhaust gas. The air supply unit 163 supplies combustion air (primary air and secondary air) to the furnace 161.
　なお、火炉１６１において微粉炭を燃焼させると、石炭灰（石炭の燃焼残渣）が生成される。石炭灰の生成により、前述したスラッギング及びファウリングと呼ばれる現象が発生する。スラッギングは、溶融した灰粒子がバーナ付近、ボイラ吊下げ管、炉壁、水冷壁管等に付着、堆積する現象であり、ガス流路の閉鎖等の問題を引き起こす。また、ファウリングは、蒸気となった硫酸化合物が伝熱管の表面に付着し、その上に燃焼灰の付着層が形成される現象であり、伝熱管の腐食等の問題を引き起こす。スラッギング及びファウリングは、灰融点が低くなると発生しやすくなる。 When pulverized coal is burned in the furnace 161, coal ash (coal combustion residue) is generated. Due to the generation of coal ash, the phenomenon called slagging and fouling described above occurs. Slagging is a phenomenon in which molten ash particles adhere to and accumulate near the burner, boiler suspension pipe, furnace wall, water-cooled wall pipe, and the like, causing problems such as closing of the gas flow path. In addition, fouling is a phenomenon in which the sulfuric acid compound that has become vapor adheres to the surface of the heat transfer tube, and an adhesion layer of combustion ash is formed thereon, which causes problems such as corrosion of the heat transfer tube. Slagging and fouling are likely to occur when the ash melting point is lowered.
　微粉炭燃焼部１６は、後述するように、微粉炭を完全燃焼させるのに必要な空気を、バーナ６１とバーナの上部に設けられた空気供給口６２の２箇所に分けて供給する、いわゆる二段燃焼方式で構成されている。バーナ６１には、微粉炭が一次空気及び排ガスと共に供給される。空気供給口６２には、二次空気が排ガスと共に供給される。なお、バーナ６１及び空気供給口６２に供給される排ガスは、微粉炭燃焼部１６から排出された排ガスの一部を再循環させたものである。 As will be described later, the pulverized coal combustion unit 16 supplies the air necessary for complete combustion of the pulverized coal in two places, ie, a burner 61 and an air supply port 62 provided in the upper part of the burner. It is composed of a stage combustion method. The burner 61 is supplied with pulverized coal together with primary air and exhaust gas. Secondary air is supplied to the air supply port 62 together with the exhaust gas. The exhaust gas supplied to the burner 61 and the air supply port 62 is obtained by recirculating part of the exhaust gas discharged from the pulverized coal combustion unit 16.
　微粉炭燃焼部１６において、バーナ６１に供給される空気（酸素）が多いと、燃焼温度が高くなり、石炭灰と共に窒素酸化物（ＮＯｘ）が大量に発生する。そのため、バーナ６１に供給する一次空気及び排ガスの配分量を調整して、酸素不足の状態で微粉炭を燃焼させることにより、窒素酸化物の発生を抑制できる。また、空気供給口６２に供給する二次空気及び排ガスの配分量を調整して、酸素を増やすことにより、空気供給口６２から火炉出口までの間で燃焼反応をより促進させることができる。 In the pulverized coal combustion unit 16, when the air (oxygen) supplied to the burner 61 is large, the combustion temperature becomes high, and a large amount of nitrogen oxide (NOx) is generated together with coal ash. Therefore, by adjusting the distribution amount of the primary air and the exhaust gas supplied to the burner 61 and burning the pulverized coal in a state where oxygen is insufficient, the generation of nitrogen oxides can be suppressed. Further, by adjusting the distribution amount of the secondary air and exhaust gas supplied to the air supply port 62 and increasing oxygen, the combustion reaction can be further promoted between the air supply port 62 and the furnace outlet.
　先に説明したように、火炉１６１において微粉炭を燃焼させると、石炭灰が生成される。また、石炭灰と共に、二酸化硫黄（ＳＯ２）、三酸化硫黄（ＳＯ３）等の硫黄酸化物（ＳＯｘ）及び窒素酸化物（ＮＯｘ）等の排ガスが発生する。これら石炭灰及び排ガスは、石炭灰処理部１８に排出される。 As described above, when pulverized coal is burned in the furnace 161, coal ash is generated. Further, together with coal ash, exhaust gases such as sulfur oxide (SOx) such as sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ) and nitrogen oxide (NOx) are generated. These coal ash and exhaust gas are discharged to the coal ash treatment unit 18.
　＜Ａ－４：石炭灰処理部１８＞
　石炭灰処理部１８は、脱硝装置１８１と、集塵機１８２と、石炭灰回収サイロ１８３と、を備える。 <A-4: Coal ash treatment unit 18>
The coal ash treatment unit 18 includes a denitration device 181, a dust collector 182, and a coal ash collection silo 183.
　脱硝装置１８１は、微粉炭燃焼部１６から排出された排ガス中の窒素酸化物を除去する。脱硝装置１８１としては、比較的高温（３００～４００℃）の排ガス中に還元剤としてアンモニアガスを注入し、脱硝触媒との作用により排ガス中の窒素酸化物を無害な窒素と水蒸気に分解する、いわゆる乾式アンモニア接触還元法が好適に用いられる。 The denitration device 181 removes nitrogen oxides in the exhaust gas discharged from the pulverized coal combustion unit 16. As the denitration device 181, ammonia gas is injected as a reducing agent into a relatively high temperature (300 to 400 ° C.) exhaust gas, and nitrogen oxides in the exhaust gas are decomposed into harmless nitrogen and water vapor by the action of the denitration catalyst. A so-called dry ammonia catalytic reduction method is preferably used.
　集塵機１８２は、排ガス中の石炭灰（煤塵）を電極で収集する。集塵機１８２は、複数段設けられていることが好ましい。集塵機１８２により捕集された石炭灰は、石炭灰回収サイロ１８３において一時貯蔵される。石炭灰が除去された排ガスは、脱硫装置（不図示）で硫黄酸化物が除去された後、煙突から排出される。
　石炭灰回収サイロ１８３は、集塵機１８２により捕集された石炭灰を一時貯蔵する。 The dust collector 182 collects coal ash (dust) in the exhaust gas with an electrode. The dust collectors 182 are preferably provided in a plurality of stages. Coal ash collected by the dust collector 182 is temporarily stored in the coal ash recovery silo 183. The exhaust gas from which the coal ash has been removed is discharged from the chimney after the sulfur oxide is removed by a desulfurization apparatus (not shown).
The coal ash collection silo 183 temporarily stores the coal ash collected by the dust collector 182.
＜Ａ－５：スラッギング抑制剤供給部２０＞
　スラッギング抑制剤供給部２０は、微粉炭燃焼部１６にスラッギング抑制剤を供給する。本実施形態において、スラッギング抑制剤供給部２０は、スラッギング抑制剤を火炉１６１の８２５℃から石炭灰融点温度までの領域に供給する。なお、本明細書において、「石炭灰融点温度」とは、石炭の炭種によって異なるが、一般的に１２２０℃から１６００℃までの間の温度である。すなわち、本発明において、通常、スラッギング抑制剤を供給する領域は、石炭の炭種により、最も狭い場合で、火炉１６１の８２５℃から１２２０℃までの領域、最も広い場合で、火炉１６１の８２５℃から１６００℃までの領域となる。スラッギング抑制剤を供給する位置については後述する。 <A-5: Slugging inhibitor supply unit 20>
The slagging inhibitor supply unit 20 supplies the slagging inhibitor to the pulverized coal combustion unit 16. In the present embodiment, the slagging inhibitor supply unit 20 supplies the slagging inhibitor to the region of the furnace 161 from 825 ° C. to the coal ash melting point temperature. In this specification, the “coal ash melting point temperature” is generally a temperature between 1220 ° C. and 1600 ° C., although it varies depending on the coal type of coal. That is, in the present invention, the region where the slagging inhibitor is normally supplied is the narrowest region depending on the coal type of coal, the region from 825 ° C to 1220 ° C of the furnace 161, and the widest region of 825 ° C of the furnace 161. To 1600 ° C. The position where the slagging inhibitor is supplied will be described later.
　スラッギング抑制剤は、アルカリ土類金属の化合物であり、例えば、炭酸カルシウム（ＣａＣＯ３）等のカルシウム含有物である。本実施形態では、スラッギング抑制剤として、石灰石を用いた例について説明する。なお、スラッギング抑制剤は、粒状又は粉末状であることが好ましい。スラッギング抑制剤の粒径は、平均粒径が１０μｍ～１００μｍであることが好ましく、１０μｍ～７０μｍであることがより好ましい。 The slagging inhibitor is an alkaline earth metal compound, for example, a calcium-containing material such as calcium carbonate (CaCO 3 ). In this embodiment, an example in which limestone is used as a slagging inhibitor will be described. The slagging inhibitor is preferably granular or powdery. The average particle size of the slagging inhibitor is preferably 10 μm to 100 μm, and more preferably 10 μm to 70 μm.
＜Ｂ：本発明に係るスラッギング抑制方法＞
　本発明に係るスラッギング抑制方法は、石炭を粉砕して微粉炭を製造する微粉炭機と、前記微粉炭機で製造された微粉炭を一次空気及び前記一次空気の後段に供給される二次空気により燃焼させる燃焼ボイラと、を備えた石炭火力発電システムにおけるスラッギング抑制方法であって、前記燃焼ボイラにおけるスラッギングを抑制するスラッギング抑制剤を、前記燃焼ボイラ中、８２５℃から石炭灰融点温度までの領域に供給することを特徴とする。以下、本発明に係るスラッギング抑制方法を、上述した微粉炭燃焼施設１を用いて説明する。 <B: Slagging suppression method according to the present invention>
The slagging suppression method according to the present invention includes a pulverized coal machine that pulverizes coal to produce pulverized coal, and secondary air that supplies the pulverized coal produced by the pulverized coal machine to primary air and a subsequent stage of the primary air. And a slagging suppression method in a coal-fired power generation system provided with a combustion boiler, wherein a slagging inhibitor for suppressing slagging in the combustion boiler is a region from 825 ° C. to a coal ash melting point temperature in the combustion boiler. It is characterized by supplying to. Hereinafter, the slugging suppression method according to the present invention will be described using the pulverized coal combustion facility 1 described above.
　本発明に係るスラッギング抑制方法は、石炭を供給する石炭供給工程Ｓ１０と、供給された石炭を粉砕して微粉炭を生成する微粉炭生成工程Ｓ２０と、微粉炭を燃焼させる微粉炭燃焼工程Ｓ３０と、微粉炭の燃焼により生成された石炭灰を処理する石炭灰処理工程Ｓ４０と、スラッギング抑制剤を供給するスラッギング抑制剤供給工程Ｓ５０と、を含む。このうち、石炭供給工程Ｓ１０から石炭灰処理工程Ｓ４０までの各工程は、それぞれ微粉炭燃焼施設１の石炭供給部１２、微粉炭生成部１４、微粉炭燃焼部１６、石炭灰処理部１８において行われる。そして、スラッギング抑制剤供給工程Ｓ５０は、上述した微粉炭燃焼工程Ｓ３０で行われる。 The slagging suppression method according to the present invention includes a coal supply step S10 for supplying coal, a pulverized coal generation step S20 for pulverizing the supplied coal to generate pulverized coal, and a pulverized coal combustion step S30 for burning the pulverized coal. And a coal ash treatment step S40 for treating coal ash generated by the combustion of pulverized coal, and a slagging inhibitor supply step S50 for supplying a slagging inhibitor. Among these, each process from coal supply process S10 to coal ash treatment process S40 is performed in coal supply part 12, pulverized coal generation part 14, pulverized coal combustion part 16, and coal ash treatment part 18 of pulverized coal combustion facility 1, respectively. Is called. And slagging inhibitor supply process S50 is performed by pulverized coal combustion process S30 mentioned above.
　＜石炭供給工程Ｓ１０＞
　まず、石炭供給工程Ｓ１０では、石炭バンカ１２１に貯蔵された石炭が、給炭機１２２により、微粉炭機１４１に供給される。なお、この微粉炭機１４１に供給される石炭は、具体的には瀝青炭、亜瀝青炭、褐炭等であるが、これらの石炭に限定されるものではなく、微粉炭燃焼が行える石炭であればよい。 <Coal supply process S10>
First, in the coal supply step S <b> 10, the coal stored in the coal bunker 121 is supplied to the pulverized coal machine 141 by the coal feeder 122. The coal supplied to the pulverized coal machine 141 is specifically bituminous coal, subbituminous coal, lignite, etc., but is not limited to these coals, and may be any coal that can perform pulverized coal combustion. .
　＜微粉炭生成工程Ｓ２０＞
　次に、微粉炭生成工程では、給炭機１２２から供給された石炭が微粉炭機１４１により粉砕され、微粉炭が製造される。製造された微粉炭は、火炉１６１に供給される。この微粉炭の平均の粒度は、微粉炭燃焼で一般的に用いられる粒径範囲であればよく、一般的には、７４μｍ以下８０ｗｔ％以上の粉砕度である。 <Pulverized coal production process S20>
Next, in the pulverized coal production step, the coal supplied from the coal feeder 122 is pulverized by the pulverized coal machine 141 to produce pulverized coal. The produced pulverized coal is supplied to the furnace 161. The average particle size of the pulverized coal may be in the particle size range generally used in pulverized coal combustion, and is generally a pulverization degree of 74 μm or less and 80 wt% or more.
　＜微粉炭燃焼工程Ｓ３０＞
　次に、微粉炭燃焼工程では、微粉炭機１４１で生成された微粉炭が、火炉１６１により燃焼される。微粉炭は、火炉１６１内のバーナゾーン１６１ａ（後述）付近で燃焼するが、このときの炉内温度は１３００℃～１５００℃に達する。燃焼によって生成される石炭灰は、矢印の方向に沿って上昇して排ガスと共に脱硝装置１８１（石炭灰処理部１８）へ送られる。なお、バーナゾーン１６１ａの上部付近における炉内温度は、８２５℃から石炭灰融点温度までとなる。 <Pulverized coal combustion process S30>
Next, in the pulverized coal combustion process, the pulverized coal generated by the pulverized coal machine 141 is burned by the furnace 161. The pulverized coal burns in the vicinity of a burner zone 161a (described later) in the furnace 161, and the furnace temperature at this time reaches 1300 ° C to 1500 ° C. The coal ash produced by the combustion rises along the direction of the arrow and is sent to the denitration device 181 (coal ash treatment unit 18) together with the exhaust gas. The furnace temperature in the vicinity of the upper part of the burner zone 161a is from 825 ° C. to the coal ash melting temperature.
　＜石炭灰処理工程Ｓ４０＞
　次に、石炭灰処理工程では、微粉炭の燃焼によって発生した排ガスが脱硝装置１８１において脱硝され、更に集塵機１８２によって排ガス中の石炭灰が集塵される。集塵機１８２により捕集された石炭灰は、石炭灰回収サイロ１８３に搬送される。また、石炭灰が除去された排ガスは、脱硫装置（不図示）で硫黄酸化物が除去された後、煙突から排出される。 <Coal ash treatment process S40>
Next, in the coal ash treatment process, the exhaust gas generated by the combustion of the pulverized coal is denitrated in the denitration device 181, and the coal ash in the exhaust gas is further collected by the dust collector 182. The coal ash collected by the dust collector 182 is conveyed to the coal ash collection silo 183. The exhaust gas from which the coal ash has been removed is discharged from the chimney after the sulfur oxide is removed by a desulfurization apparatus (not shown).
　＜スラッギング抑制剤供給工程Ｓ５０＞
　本発明の特徴であるスラッギング抑制剤を供給する工程であるスラッギング抑制剤供給工程Ｓ５０は、図１に示すように、微粉炭燃焼工程Ｓ３０で行われる（図１のＳ５１）。以下、微粉炭燃焼工程Ｓ３０で行われるスラッギング抑制剤の供給について説明する。 <Slagging inhibitor supply process S50>
A slagging inhibitor supply step S50, which is a step of supplying a slagging inhibitor, which is a feature of the present invention, is performed in a pulverized coal combustion step S30 as shown in FIG. 1 (S51 in FIG. 1). Hereinafter, the supply of the slagging inhibitor performed in the pulverized coal combustion step S30 will be described.
　図２は、微粉炭燃焼施設１における火炉１６１とその周辺の構成を示す図である。
　図２に示すように、火炉１６１の下方には、バーナ６１が設けられている。バーナ６１には、微粉炭機１４１（図１参照）から供給された微粉炭２００、空気供給機１６３から供給された一次空気２０１及び再循環された排ガス２０３が供給される。微粉炭２００は、火炉１６１において、主にバーナゾーン１６１ａで燃焼する。 FIG. 2 is a diagram showing a configuration of the furnace 161 and its surroundings in the pulverized coal combustion facility 1.
As shown in FIG. 2, a burner 61 is provided below the furnace 161. The burner 61 is supplied with pulverized coal 200 supplied from the pulverized coal machine 141 (see FIG. 1), primary air 201 supplied from the air supply unit 163, and recirculated exhaust gas 203. The pulverized coal 200 burns in the furnace 161 mainly in the burner zone 161a.
　バーナ６１の上部には、空気供給口６２が設けられている。空気供給口６２には、空気供給機１６３から供給された二次空気２０２及び再循環された排ガス２０３が供給される。空気供給口６２から二次空気２０２及び排ガス２０３を供給することにより、バーナゾーン１６１ａ付近で未燃焼であった微粉炭の燃焼反応が促進され、微粉炭を完全燃焼させることができる。火炉１６１において、微粉炭の燃焼により生じた排ガス２０３（燃焼ガス）は、石炭灰と共に火炉出口１６１ｂから後段の脱硝装置１８１（石炭灰処理部１８）へ排出される。上述のように、排出された排ガス２０３の一部は再循環され、バーナ６１及び空気供給口６２に供給される。
　なお、図示していないが、火炉１６１において、バーナ６１の上部及び火炉出口１６１ｂ付近には、過熱器、再熱器、節炭器等の熱交換ユニットが設けられている。 An air supply port 62 is provided in the upper part of the burner 61. The air supply port 62 is supplied with the secondary air 202 supplied from the air supply machine 163 and the recirculated exhaust gas 203. By supplying the secondary air 202 and the exhaust gas 203 from the air supply port 62, the combustion reaction of the pulverized coal that has not been burned in the vicinity of the burner zone 161a is promoted, and the pulverized coal can be completely burned. In the furnace 161, the exhaust gas 203 (combustion gas) generated by the combustion of pulverized coal is discharged together with the coal ash from the furnace outlet 161b to the subsequent denitration device 181 (the coal ash treatment unit 18). As described above, a part of the discharged exhaust gas 203 is recirculated and supplied to the burner 61 and the air supply port 62.
Although not shown, in the furnace 161, heat exchange units such as a superheater, a reheater, and a economizer are provided near the upper portion of the burner 61 and the furnace outlet 161b.
　微粉炭燃焼部１６は、図２に示すように、排ガス２０３の一部を再循環させてバーナ６１及び空気供給口６２に供給するための設備として、ガス再循環通風機６３と、集塵機６４と、排ガス通路１００と、を備える。 As shown in FIG. 2, the pulverized coal combustion unit 16 recirculates a part of the exhaust gas 203 and supplies it to the burner 61 and the air supply port 62 as a gas recirculation ventilator 63, a dust collector 64, The exhaust gas passage 100 is provided.
　ガス再循環通風機６３は、火炉出口１６１ｂから排出された排ガス２０３の一部を取り込み、バーナ６１及び空気供給口６２に送り込む送風ファンである。
　集塵機６４は、排ガス２０３に含まれる石炭灰（煤塵）を収集する装置である。集塵機６４として、例えば、機械式の集塵機を用いることができる。 The gas recirculation ventilator 63 is a blower fan that takes in a part of the exhaust gas 203 discharged from the furnace outlet 161 b and sends it to the burner 61 and the air supply port 62.
The dust collector 64 is a device that collects coal ash (dust) contained in the exhaust gas 203. As the dust collector 64, for example, a mechanical dust collector can be used.
　排ガス通路１００は、火炉出口１６１ｂから排出された排ガス２０３の一部をバーナ６１及び空気供給口６２に導くための送風ダクトである。排ガス通路１００は、第１排ガス通路１１０と、第２排ガス通路１２０と、第３排ガス通路１３０と、を備える。 The exhaust gas passage 100 is an air duct that guides part of the exhaust gas 203 discharged from the furnace outlet 161 b to the burner 61 and the air supply port 62. The exhaust gas passage 100 includes a first exhaust gas passage 110, a second exhaust gas passage 120, and a third exhaust gas passage 130.
　第１排ガス通路１１０は、排ガス２０３を火炉出口１６１ｂ側から取り出す通路である。第１排ガス通路１１０には、ガス再循環通風機６３及び集塵機６４が接続されている。第１排ガス通路１１０の上流側の端部は、火炉出口１６１ｂ側に接続されている。第１排ガス通路１１０の下流側の端部は、集塵機６４の排ガス入口側に接続されている。 The first exhaust gas passage 110 is a passage for taking out the exhaust gas 203 from the furnace outlet 161b side. A gas recirculation ventilator 63 and a dust collector 64 are connected to the first exhaust gas passage 110. The upstream end of the first exhaust gas passage 110 is connected to the furnace outlet 161b side. The downstream end of the first exhaust gas passage 110 is connected to the exhaust gas inlet side of the dust collector 64.
　第２排ガス通路１２０は、排ガス２０３をバーナ６１に導く通路である。第２排ガス通路１２０の上流側の端部は、集塵機６４の排ガス出口側に接続されている。第２排ガス通路１２０の下流側の端部は、バーナ６１の排ガス導入部（不図示）に接続されている。 The second exhaust gas passage 120 is a passage that guides the exhaust gas 203 to the burner 61. The upstream end of the second exhaust gas passage 120 is connected to the exhaust gas outlet side of the dust collector 64. The downstream end portion of the second exhaust gas passage 120 is connected to an exhaust gas introduction portion (not shown) of the burner 61.
　第３排ガス通路１３０は、排ガス２０３を空気供給口６２に導く通路である。第３排ガス通路１３０の上流側の端部は、上述した第２排ガス通路１２０の上流側の端部と共に集塵機６４の排ガス出口側に接続されている。第３排ガス通路１３０の下流側の端部は、空気供給口６２の排ガス導入部（不図示）に接続されている。 The third exhaust gas passage 130 is a passage that guides the exhaust gas 203 to the air supply port 62. The upstream end of the third exhaust gas passage 130 is connected to the exhaust gas outlet side of the dust collector 64 together with the upstream end of the second exhaust gas passage 120 described above. The downstream end of the third exhaust gas passage 130 is connected to an exhaust gas introduction part (not shown) of the air supply port 62.
　第３排ガス通路１３０には、スラッギング抑制剤通路１４０が接続されている。スラッギング抑制剤通路１４０は、スラッギング抑制剤供給部２０から第３排ガス通路１３０にスラッギング抑制剤２０４を供給するための通路である。スラッギング抑制剤２０４は、第３排ガス通路１３０において、集塵機６４と空気供給口６２との間に、間欠的に所定の時間間隔で、所定量以上供給される。このように、第３排ガス通路１３０を含む排ガス通路１００は、排ガス２０３の一部を二次空気２０２と混合させるための流路として機能する。
　なお、排ガス通路１００において、第２排ガス通路１２０及び第３排ガス通路１３０の途中に、排ガス２０３を下流側に押し込む送風ファンを設けてもよい。 A slagging inhibitor passage 140 is connected to the third exhaust gas passage 130. The slagging inhibitor passage 140 is a passage for supplying the slagging inhibitor 204 from the slagging inhibitor supply unit 20 to the third exhaust gas passage 130. In the third exhaust gas passage 130, the slagging inhibitor 204 is intermittently supplied between the dust collector 64 and the air supply port 62 at a predetermined time interval. As described above, the exhaust gas passage 100 including the third exhaust gas passage 130 functions as a flow channel for mixing a part of the exhaust gas 203 with the secondary air 202.
In the exhaust gas passage 100, a blower fan that pushes the exhaust gas 203 downstream may be provided in the middle of the second exhaust gas passage 120 and the third exhaust gas passage 130.
　図２に示すように、火炉出口１６１ｂ側から取り出された排ガス２０３の一部は、第１排ガス通路１１０によりガス再循環通風機６３を通じて集塵機６４に導かれる。そして、排ガス２０３は、集塵機６４の排ガス出口側で第２排ガス通路１２０及び第３排ガス通路１３０に分岐して、バーナ６１及び空気供給口６２にそれぞれ導かれる。バーナ６１に導かれた排ガス２０３は、微粉炭２００及び一次空気２０１と共にバーナ６１から火炉１６１に供給される。また、空気供給口６２に導かれた排ガス２０３は、二次空気２０２及びスラッギング抑制剤２０４と共に空気供給口６２から火炉１６１に供給される。 As shown in FIG. 2, a part of the exhaust gas 203 taken out from the furnace outlet 161 b side is guided to the dust collector 64 through the gas recirculation ventilator 63 by the first exhaust gas passage 110. The exhaust gas 203 branches into the second exhaust gas passage 120 and the third exhaust gas passage 130 on the exhaust gas outlet side of the dust collector 64 and is guided to the burner 61 and the air supply port 62, respectively. The exhaust gas 203 guided to the burner 61 is supplied from the burner 61 to the furnace 161 together with the pulverized coal 200 and the primary air 201. Further, the exhaust gas 203 guided to the air supply port 62 is supplied to the furnace 161 from the air supply port 62 together with the secondary air 202 and the slagging inhibitor 204.
　本実施形態において、例えば空気供給口６２から、スラッギング抑制剤２０４を火炉１６１の８２５℃から石炭灰融点温度までの領域に投入することにより、スラッギングが抑制されるメカニズムは、以下のようなものと考えられる。 In this embodiment, for example, the mechanism in which slagging is suppressed by introducing the slagging inhibitor 204 from the air supply port 62 into the furnace 161 in the region from 825 ° C. to the coal ash melting point temperature is as follows. Conceivable.
　スラッギング抑制剤２０４である炭酸カルシウム（ＣａＣＯ３）を二次空気２０２と共に火炉１６１に供給すると、スラッギング抑制剤２０４は、空気供給口６２からバーナゾーン１６１ａの上部付近に投入される。この付近の炉内温度は８２５℃から石炭灰融点温度であるため、ＣａＣＯ３は、ＣａＯとＣＯ２とに分解される。分解されたＣａＯは、化合物としての融点は低いが、分解されたＣａＯの融点は２５７０℃程度となるため、バーナゾーン１６１ａに比べて温度の低いバーナゾーン１６１ａの上部付近では、石炭灰と反応しにくくなる。このように、スラッギング抑制剤２０４を空気供給口６２からバーナゾーン１６１ａの上部付近に供給すると、ＣａＯが単独で多く存在することになるため、灰融点が高くなると推測される。 When calcium carbonate (CaCO 3 ), which is the slagging inhibitor 204, is supplied to the furnace 161 together with the secondary air 202, the slagging inhibitor 204 is introduced into the vicinity of the upper portion of the burner zone 161a from the air supply port 62. Since the furnace temperature in the vicinity is from 825 ° C. to the coal ash melting point temperature, CaCO 3 is decomposed into CaO and CO 2 . Although the decomposed CaO has a low melting point as a compound, the decomposed CaO has a melting point of about 2570 ° C., and therefore reacts with coal ash in the vicinity of the upper part of the burner zone 161a where the temperature is lower than that of the burner zone 161a. It becomes difficult. As described above, when the slagging inhibitor 204 is supplied from the air supply port 62 to the vicinity of the upper portion of the burner zone 161a, a large amount of CaO is present alone, so that the ash melting point is estimated to increase.
　また、スラッギング抑制剤２０４を、間欠的に所定の時間間隔で供給することにより、バーナ付近、ボイラ吊下げ管、炉壁、水冷壁管等に生成するスラッギングは、図３に示されるように、Ｆｅ，Ｃａ，Ｓｉ，Ａｌ，Ｍｇ等の低融点化合物とＣａＯの塊とのサンドイッチ構造となる。これにより、スラッギングは、低融点化合物とＣａＯの塊との境界面で剥落しやすくなり、スラッギングの巨大化が防止される。 Further, by supplying the slagging inhibitor 204 intermittently at predetermined time intervals, the slagging generated in the vicinity of the burner, the boiler suspension pipe, the furnace wall, the water-cooled wall pipe, etc., as shown in FIG. A sandwich structure of a low melting point compound such as Fe, Ca, Si, Al, and Mg and a mass of CaO is obtained. As a result, slagging is easily peeled off at the interface between the low melting point compound and the CaO lump, thereby preventing the slagging from becoming enormous.
　ここで、低融点化合物を生成させやすいとされる炭酸カルシウム（ＣａＣＯ３）を、適切な場所に添加することで、低融点化合物を生成しない点について説明する。 Here, the calcium carbonate which is easy to produce a low-melting compounds (CaCO 3), by adding the appropriate location, is described that does not generate a low-melting compound.
　成分中のカルシウム分が相対的に少ない「Ａ炭」のみを専焼させて生成される灰の灰融点、成分中のカルシウム分が相対的に多い「Ｂ炭」のみを専燃させて生成される灰の灰融点、「Ａ炭」と「Ｂ炭」を混合した「Ａ炭＋Ｂ炭」を燃焼させて生成される灰の灰融点、及び「Ａ炭」を燃焼させると共に、炭酸カルシウムを９５０℃付近に別添加して生成される灰の灰融点を測定した。なお、９５０℃付近に別添加する炭酸カルシウムの量は、「Ａ炭とＢ炭」を燃焼した場合と、灰中のカルシウム換算で同量（ＣａＯ：３．１％）となるように添加した。測定結果を、表１に示す。 　 Ash melting point of ash produced by burning only "A charcoal" with relatively low calcium content in the component, produced by burning only "B charcoal" with relatively high calcium content in the component Ash ash melting point, ash melting point of ash produced by burning “A charcoal + B charcoal” mixed with “A charcoal” and “B charcoal”, and “A charcoal” burning, and calcium carbonate at 950 ° C. The ash melting point of the ash produced by separately adding in the vicinity was measured. In addition, the amount of calcium carbonate added separately at around 950 ° C. was added so as to be the same amount (CaO: 3.1%) in terms of calcium in ash when “A charcoal and B charcoal” were burned. . The measurement results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示されるように、「Ａ炭」のみを専焼して生成される灰の灰融点は、１３１１～１３６４℃であった。「Ｂ炭」のみを専焼して生成される灰の灰融点は、１２３４～１３０１℃であった。「Ａ炭＋Ｂ炭」を燃焼して生成される灰の灰融点は、「Ａ炭」のみを燃焼して生成される灰の灰融点よりも下降し、１２３５～１３０１℃であった。「Ａ炭」を燃焼させると共に、炭酸カルシウムを９５０℃付近に別添加して生成される灰の灰融点は、「Ａ炭」のみを燃焼して生成される灰の灰融点よりも上昇し、１３２３～１３８７℃であった。 As shown in Table 1, the ash melting point of the ash produced by exclusively burning “A charcoal” was 1311 to 1364 ° C. The ash melting point of the ash produced by burning only “B charcoal” was 1234 to 1301 ° C. The ash melting point of the ash produced by burning “A coal + B coal” was 1235 to 1301 ° C., which was lower than the ash melting point of the ash produced by burning only “A coal”. The ash melting point of the ash produced by burning “A charcoal” and adding calcium carbonate separately at around 950 ° C. is higher than the ash melting point of the ash produced by burning only “A charcoal”, It was 1323 to 1387 ° C.
　すなわち、「Ａ炭＋Ｂ炭」を燃焼した場合と、「Ａ炭」を燃焼し、炭酸カルシウムを別添加した場合とでは、灰中のカルシウム量が同量であるにもかかわらず、炭酸カルシウムを９５０℃付近に別添加することにより、灰融点は上昇した。このことから、炭酸カルシウムを９５０℃付近に別に投入すると、灰融点は下がらず低融点化合物を生成しにくい事を確認した。 That is, when “A charcoal + B charcoal” is burned and “A charcoal” is burned and calcium carbonate is added separately, calcium carbonate in the ash is the same in spite of the same amount of calcium carbonate. The ash melting point was increased by adding it separately at around 950 ° C. From this, it was confirmed that when calcium carbonate was separately added in the vicinity of 950 ° C., the ash melting point did not decrease and it was difficult to produce a low melting point compound.
　また、本実施形態において、スラッギング抑制剤２０４を火炉１６１中、微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に供給することにより、微量元素の溶出が抑制される。そのメカニズムは、以下のようなものと考えられる。
　分解されたＣａＯは、石炭灰に含まれる微量元素である酸化セレン、三酸化二ヒ素、酸化ホウ素等と反応して、それぞれ亜セレン酸カルシウム、ヒ酸カルシウム、ホウ酸カルシウム等の難溶性不溶性化合物を生成する。すなわち、微量元素は、ＣａＯにより化学的に捕捉されて難溶性不溶性化合物が生成される。従って、スラッギング抑制剤２０４を火炉１６１中、微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に投入することにより、石炭灰に含まれる微量元素の挙動が制御され、より多くの微量元素の溶出を抑制できる。 Moreover, in this embodiment, by supplying the slagging inhibitor 204 to the region from 825 ° C. to the coal ash melting point temperature in the furnace 161, which is subsequent to the pulverized coal combustion location, the elution of trace elements is suppressed. . The mechanism is considered as follows.
The decomposed CaO reacts with selenium oxide, arsenic trioxide, boron oxide, and the like, which are trace elements contained in coal ash, and is insoluble insoluble compounds such as calcium selenite, calcium arsenate, and calcium borate, respectively. Is generated. That is, trace elements are chemically captured by CaO to produce a hardly soluble insoluble compound. Therefore, by introducing the slagging inhibitor 204 into the furnace 161 in the region from 825 ° C. to the coal ash melting point, which is after the pulverized coal combustion location, the behavior of the trace elements contained in the coal ash is controlled, Elution of more trace elements can be suppressed.
　以上のように、本実施形態の微粉炭燃焼施設１では、スラッギング抑制剤２０４が、火炉１６１中、微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に供給されるため、石炭灰からの微量元素の溶出を抑制しつつ、スラッギングの発生を抑制できる。更には、微量元素の溶出を抑制することにより、各種法規制を順守することができる。 As described above, in the pulverized coal combustion facility 1 of the present embodiment, the slagging inhibitor 204 is supplied to a region from 825 ° C. to the coal ash melting point temperature in the furnace 161, after the combustion location of the pulverized coal. Therefore, generation | occurrence | production of slagging can be suppressed, suppressing the elution of the trace element from coal ash. Furthermore, various laws and regulations can be observed by suppressing the elution of trace elements.
　また、本実施形態の微粉炭燃焼施設１は、従来は困難であった微量元素の含有量が多い石炭種についても微量元素の溶出を十分に抑制できるため、適用可能な炭種を大幅に増やすことができる。これにより、例えば、微量元素の含有量が多い安価な石炭種を使用することにより、燃料費コストの削減を図ることができる。 In addition, the pulverized coal combustion facility 1 of the present embodiment can sufficiently suppress the elution of trace elements even for a coal type having a high content of trace elements, which has been difficult in the past, and therefore greatly increases the applicable coal types. be able to. Thereby, for example, the fuel cost cost can be reduced by using an inexpensive coal type having a high trace element content.
　以上、本発明の実施形態について説明したが、本発明は、上述した実施形態に限定されない。実施形態に記載された効果は、本発明により得られる最も好適な効果を列挙したにすぎない。本発明による効果は、実施形態に記載したものに限定されない。 As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above. The effects described in the embodiments only list the most preferable effects obtained by the present invention. The effect by this invention is not limited to what was described in embodiment.
　本実施形態では、スラッギング抑制剤として、炭酸カルシウム（ＣａＣＯ３）を用いた例について説明したが、これに限定されない。スラッギング抑制剤として、他のアルカリ土類金属の化合物を用いることもできる。 In the present embodiment, an example in which calcium carbonate (CaCO 3 ) is used as a slagging inhibitor has been described, but the present invention is not limited to this. Other alkaline earth metal compounds can also be used as a slagging inhibitor.
　本実施形態では、スラッギング抑制剤を、間欠的に、所定の時間間隔で供給する態様について述べたが、これには限定されず、連続的に供給してもよい。この場合、スラッギングにおいては、図４に示すように、主として低融点化合物からなるスラッギング中の所々に、ＣａＯの島が生成される構成となる。この場合、小さな粒径の球形状となったＣａＯと低融点化合物との間に、境界面が存在することにより、スラッギングは顆粒状に崩れやすい構造となっているため、スラッギングの巨大化を防ぐことが可能となる。 In the present embodiment, the aspect in which the slagging inhibitor is intermittently supplied at predetermined time intervals has been described, but the present invention is not limited to this and may be supplied continuously. In this case, as shown in FIG. 4, in the slagging, CaO islands are generated in places during the slagging mainly composed of a low melting point compound. In this case, since there is a boundary surface between CaO in a spherical shape with a small particle size and the low melting point compound, slagging has a structure that tends to collapse into a granular shape, thus preventing enlargement of slagging. It becomes possible.
　本実施形態では、スラッギング抑制剤を第３排ガス通路１３０に供給する例について説明したが、これに限定されない。スラッギング抑制剤を、火炉１６１中、微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に供給できれば、スラッギング抑制剤を供給する位置は適宜に選択可能である。例えば、スラッギング抑制剤を、ガス再循環通風機６３と集塵機６４との間（第１排ガス通路１１０）から供給してもよい。 In the present embodiment, the example in which the slagging inhibitor is supplied to the third exhaust gas passage 130 has been described, but the present invention is not limited to this. If the slagging inhibitor can be supplied to the region from 825 ° C. to the coal ash melting point temperature in the furnace 161 after the pulverized coal combustion location, the position for supplying the slagging inhibitor can be appropriately selected. For example, the slagging inhibitor may be supplied from between the gas recirculation ventilator 63 and the dust collector 64 (the first exhaust gas passage 110).
　本実施形態では、スラッギング抑制剤を二次空気及び排ガスと共に火炉１６１に供給する構成について説明したが、これに限定されない。また、スラッギング抑制剤は、二次空気を供給する位置から、蒸気、石炭石等と共に火炉１６１に供給してもよい。 In the present embodiment, the configuration in which the slagging inhibitor is supplied to the furnace 161 together with the secondary air and the exhaust gas has been described, but the present invention is not limited to this. Moreover, you may supply a slagging inhibitor to the furnace 161 with a vapor | steam, a coal stone, etc. from the position which supplies secondary air.
　１　微粉炭燃焼施設
　１２　石炭供給部
　１４　微粉炭生成部
　１６　微粉炭燃焼部
　１８　石炭灰処理部
　２０　スラッギング抑制剤供給部
　１００　排ガス通路
　１１０　第１排ガス通路
　１２０　第２排ガス通路
　１３０　第３排ガス通路
　１４０　スラッギング抑制剤通路
　１４１　微粉炭機
　Ｓ１０　石炭供給工程
　Ｓ２０　微粉炭生成工程
　Ｓ３０　微粉炭燃焼工程
　Ｓ４０　石炭灰処理工程
　Ｓ５０　スラッギング抑制剤供給工程 DESCRIPTION OF SYMBOLS 1 Pulverized coal combustion facility 12 Coal supply part 14 Pulverized coal production | generation part 16 Pulverized coal combustion part 18 Coal ash processing part 20 Slagging inhibitor supply part 100 Exhaust gas path 110 1st exhaust gas path 120 2nd exhaust gas path 130 3rd exhaust gas path 140 Slagging Inhibitor passage 141 Pulverized coal machine S10 Coal supply process S20 Pulverized coal generation process S30 Pulverized coal combustion process S40 Coal ash treatment process S50 Slagging inhibitor supply process

Claims (15)

  1. 　石炭を粉砕して微粉炭を製造する微粉炭機と、前記微粉炭機で製造された微粉炭を一次空気及び前記一次空気の後段に供給される二次空気により燃焼させる燃焼ボイラと、を備えた石炭火力発電システムにおけるスラッギング抑制方法であって、前記燃焼ボイラにおけるスラッギングを抑制するスラッギング抑制剤を、前記燃焼ボイラ中、前記微粉炭の燃焼箇所よりも後段の、８２５℃から石炭灰融点温度までの領域に供給するスラッギング抑制方法。 A pulverized coal machine that pulverizes coal to produce pulverized coal, and a combustion boiler that combusts the pulverized coal produced by the pulverized coal machine with primary air and secondary air supplied to the subsequent stage of the primary air, and A method for suppressing slagging in a coal-fired power generation system, wherein a slagging inhibitor that suppresses slagging in the combustion boiler is from 825 ° C. to a coal ash melting point temperature after the combustion location of the pulverized coal in the combustion boiler. Slagging suppression method to supply to the area.
  2. 　前記スラッギング抑制剤は、アルカリ土類金属の化合物を含む、請求項１に記載のスラッギング抑制方法。 The slagging inhibiting method according to claim 1, wherein the slagging inhibiting agent comprises an alkaline earth metal compound.
  3. 　前記スラッギング抑制剤は、炭酸カルシウム（ＣａＣＯ３）を含む、請求項１又は２に記載のスラッギング抑制方法。 The slagging inhibiting method according to claim 1 or 2, wherein the slagging inhibiting agent contains calcium carbonate (CaCO 3 ).
  4. 　前記スラッギング抑制剤を、前記二次空気と共に前記燃焼ボイラに供給する、請求項１～３のいずれか１項に記載のスラッギング抑制方法。 The slagging suppression method according to any one of claims 1 to 3, wherein the slagging inhibitor is supplied to the combustion boiler together with the secondary air.
  5. 　前記スラッギング抑制剤を、微粉炭の燃焼により発生した排ガスの一部を二次空気と混合させるための流路に供給する、請求項１～４のいずれか１項に記載のスラッギング抑制方法。 The method for suppressing slagging according to any one of claims 1 to 4, wherein the slagging inhibitor is supplied to a flow path for mixing a part of exhaust gas generated by combustion of pulverized coal with secondary air.
  6. 　前記スラッギング抑制剤を、間欠的に所定の時間間隔で供給する、請求項１～５のいずれか１項に記載のスラッギング抑制方法。 The slugging suppression method according to any one of claims 1 to 5, wherein the slugging inhibitor is intermittently supplied at predetermined time intervals.
  7. 　前記スラッギング抑制剤を、連続的に供給する、請求項１～６のいずれか１項に記載のスラッギング抑制方法。 The slagging suppressing method according to any one of claims 1 to 6, wherein the slagging suppressing agent is continuously supplied.
  8. 　石炭を粉砕して微粉炭を製造する微粉炭機と、前記微粉炭機で製造された微粉炭を一次空気及び前記一次空気の後段で供給される二次空気により燃焼させる燃焼ボイラと、を備えた石炭火力発電システムにおいて、前記燃焼ボイラにおけるスラッギングを抑制するスラッギング抑制剤を、前記燃焼ボイラ中、前記微粉炭の燃焼箇所よりも後段の８２５℃から石炭灰融点温度までの領域に供給するスラッギング抑制剤供給部を備える石炭火力発電システム。 A pulverized coal machine that pulverizes coal to produce pulverized coal, and a combustion boiler that combusts the pulverized coal produced by the pulverized coal machine with primary air and secondary air that is supplied after the primary air. In the coal-fired power generation system, the slagging inhibitor that suppresses the slagging in the combustion boiler is supplied to the region from 825 ° C. to the coal ash melting point temperature after the pulverized coal combustion location in the combustion boiler. Coal-fired power generation system with an agent supply unit.
  9. 　前記スラッギング抑制剤は、アルカリ土類金属の化合物を含む、請求項８に記載の石炭火力発電システム。 The coal-fired power generation system according to claim 8, wherein the slagging inhibitor includes an alkaline earth metal compound.
  10. 　前記スラッギング抑制剤は、炭酸カルシウム（ＣａＣＯ３）を含む、請求項８又は９に記載の石炭火力発電システム。 The coal-fired power generation system according to claim 8 or 9, wherein the slagging inhibitor includes calcium carbonate (CaCO 3 ).
  11. 　前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、前記二次空気と共に前記燃焼ボイラに供給する、請求項８～１０のいずれか１項に記載の石炭火力発電システム。 The coal-fired power generation system according to any one of claims 8 to 10, wherein the slagging inhibitor supply unit supplies the slagging inhibitor to the combustion boiler together with the secondary air.
  12. 　前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、微粉炭の燃焼により発生した排ガスの一部を二次空気と混合させるための流路に供給する、請求項８～１１のいずれか１項に記載の石炭火力発電システム。 12. The slagging inhibitor supply unit supplies the slagging inhibitor to a flow path for mixing a part of exhaust gas generated by the combustion of pulverized coal with secondary air. The coal-fired power generation system described in 1.
  13. 　前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、間欠的に所定の時間間隔で供給する、請求項８～１２のいずれか１項に記載の石炭火力発電システム。 The coal-fired power generation system according to any one of claims 8 to 12, wherein the slagging inhibitor supply unit supplies the slagging inhibitor intermittently at predetermined time intervals.
  14. 　前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、連続的に供給する、請求項８～１２のいずれか１に記載の石炭火力発電システム。 The coal-fired power generation system according to any one of claims 8 to 12, wherein the slagging inhibitor supply unit continuously supplies the slagging inhibitor.
  15. 　前記スラッギング抑制剤供給部は、前記スラッギング抑制剤を、微粉炭の燃焼により発生した排ガスの一部を二次空気と混合させるための流路に設けられたガス再循環通風機の下流側に供給する、請求項８～１４のいずれか１項に記載の石炭火力発電システム。 The slagging inhibitor supply unit supplies the slagging inhibitor to a downstream side of a gas recirculation ventilator provided in a flow path for mixing a part of exhaust gas generated by combustion of pulverized coal with secondary air. The coal-fired power generation system according to any one of claims 8 to 14.
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CN113108297A (en) * 2021-05-24 2021-07-13 西安热工研究院有限公司 Adding system and method of slag inhibitor for opposed firing boiler

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CN114263926B (en) * 2022-01-26 2024-04-02 西安热工研究院有限公司 A system and method for preventing and controlling slagging contamination of high-alkali coal boilers

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JPS6348392A (en) * 1986-08-15 1988-03-01 Toa Netsuken Kk Method of controlling clinker ash of coal exhaust gas dust
US4960577A (en) * 1988-02-04 1990-10-02 Acurex Corporation Enhanced sorbent injection combined with natural gas reburning for a sox control for coal fired boilers
US5220875A (en) * 1992-04-15 1993-06-22 American Oxycarb Corporation Method of reducing sulfur dioxide content in flue gases
US7430969B2 (en) * 2003-05-28 2008-10-07 Omni Materials, Inc. Method for reducing the amount of a sulfur dioxide in a flue gas resulting from the combustion of a fossil fuel
JP2005307117A (en) * 2004-04-26 2005-11-04 Taiho Ind Co Ltd Fuel additive for preventing slagging and method for burning fuel
JP2008170110A (en) * 2007-01-12 2008-07-24 Chugoku Electric Power Co Inc:The Method of calculating additive amount of harmful trace element elution inhibitor and method of inhibiting elution of harmful trace element using the same
JP2014507620A (en) * 2011-01-14 2014-03-27 エンバイロンメンタル・エナジー・サービシーズ・インコーポレイテッド A method for operating a furnace using bituminous coal and a method for reducing slag formation thereby
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JP2016020799A (en) * 2014-06-18 2016-02-04 ナルコジャパン合同会社 Method for controlling clinker

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Publication number Priority date Publication date Assignee Title
CN113108297A (en) * 2021-05-24 2021-07-13 西安热工研究院有限公司 Adding system and method of slag inhibitor for opposed firing boiler

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