JP2010054144A - Oxygen combustion boiler system and combustion method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler system capable of further suppressing the generation of a nitrogen oxide while recovering a carbon dioxide in a furnace of a pulverizing coal firing boiler, as an increase of carbon dioxide emission is cited as a factor of global warming, and nitrogen oxide emission is recently controlled under severe environmental restriction as it is an air-pollution substance badly affecting a human body. <P>SOLUTION: In this oxygen combustion boiler system, a dry recirculated exhaust gas dehumidified by moisture eliminating equipment is allowed to flow into a reduction atmosphere region in the boiler from a dry recirculated exhaust gas supply port. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structure of an oxyfuel boiler that combusts pulverized coal with oxygen generated by an oxygen production apparatus and recirculated exhaust gas, and a combustion system thereof.

  In recent years, an increase in carbon dioxide emissions has been cited as a cause of global warming. In particular, coal-based power generation systems generate more carbon dioxide per unit calorific value than other fossil fuels. For this reason, research and development of carbon dioxide capture and sequestration technology has been actively pursued. Among them, the oxyfuel boiler system is attracting attention as a method for recovering carbon dioxide directly from the system. An oxyfuel boiler is a system in which oxygen generated by separating nitrogen from air in advance in an oxygen production apparatus is mixed with gas obtained by recirculating part of combustion exhaust gas, and coal is burned with the mixed gas. The main components of the mixed gas are oxygen, carbon dioxide, and water vapor. Unlike conventional boilers that burn coal with air, the amount of carbon dioxide in the exhaust gas can be increased because there is less nitrogen during combustion. Furthermore, in this system, by removing the moisture in the exhaust gas generated during combustion, the carbon dioxide concentration in the entire exhaust gas can be increased to 90% or more, so even if there is no facility for separating carbon dioxide, the carbon dioxide can be used as it is. There are features that can be recovered.

  Here, the oxyfuel boiler system currently proposed is first described in Patent Document 1.

  In this patent document, it is a boiler system that burns using recovered carbon dioxide and oxygen. However, since carbon dioxide is once liquefied, energy for vaporizing again to return carbon dioxide to the boiler as a recirculated gas. Is required. Therefore, a significant reduction in plant efficiency is inevitable with this system. Further, the burner of this patent document separately supplies fuel and oxidant and burns them. It is a so-called diffusion combustion burner. In this burner, a region having a large residual amount of oxidant is formed in the vicinity of the burner due to non-uniformity in the mixing of fuel and oxidant. If nitrogen is present in this region, a large amount of nitrogen oxide is generated.

  Next, there is Patent Document 2 in which the combustion exhaust gas discharged from the boiler furnace is dust-removed and then recirculated to the boiler furnace combustion device (burner). With such a system, the flue gas having a high water content is recirculated back to the vicinity of the combustion device. Since the vicinity of the combustion apparatus (burner) is a reducing atmosphere at a high temperature by combustion, OH radicals are generated from moisture. Since the coal contains several percent of nitrogen components, cyanide and ammonia generated by coal combustion react with OH radicals, which causes generation of nitrogen oxides.

JP-A-5-231609 JP-A-6-94212

  Since nitrogen oxides are air pollutants that affect the human body, emissions are controlled under recent strict environmental regulations. Therefore, the generation amount of nitrogen oxides must be suppressed. An object of the present invention is to propose an oxyfuel boiler system that further suppresses the generation of nitrogen oxides while recovering carbon dioxide.

  In order to achieve the above object, in the oxyfuel boiler system, the dry exhaust gas dehumidified by the moisture removal equipment is caused to flow into the reducing atmosphere region in the boiler from the dry recirculation exhaust gas supply port.

  According to the present invention, the dry recirculated exhaust gas from which moisture has been removed is returned to the reducing atmosphere of the boiler furnace. As a result, the carbon dioxide concentration in the reducing atmosphere is increased, and the reduction reaction of the coal particles proceeds. It is also possible to make the local oxidation region generated in the burner a reducing atmosphere. When the reduction reaction occurs, the carbon monoxide concentration increases and the nitrogen oxide concentration decreases.

  The oxyfuel boiler system of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the examples.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an oxyfuel boiler system according to the present invention. In this embodiment, as shown in FIG. 1, the oxyfuel boiler has three upper and lower burners arranged on the front and rear walls. The burner 1 is an opposed combustion system that faces the can before and after. The burner may be arranged in other ways. The vicinity of the burner of the boiler furnace 2 is in a reducing atmosphere combustion state, and the so-called two-stage combustion is employed in which the combustion gas rising from the burner portion is oxidized by oxygen input from the oxidizing gas supply port 3 at the top of the burner. is there. Two-stage combustion is a combustion method that reduces the amount of nitrogen oxide generated. Oxygen for combustion is generated in the oxygen production facility 4. The oxygen production facility 4 is a device that separates oxygen and nitrogen from air. The generated nitrogen is mixed with exhaust gas immediately before the chimney 5 and discharged out of the system. Although the purity of oxygen can be increased depending on the level of separation, the higher the cost, the higher the cost for production. Therefore, it is considered that the power plant is used in a state where a trace amount of nitrogen remains. Moreover, the boiler furnace 2 is normally operated at a negative pressure. For this reason, air (nitrogen) flows into the boiler furnace 2 due to inleakage. Nitrogen oxides generated in the boiler furnace 2 include those derived from these gases and those derived from nitrogen contained in the coal.

  The combustion exhaust gas of 1000 ° C. or more generated in the boiler furnace 2 is absorbed by the heat exchanger 6 installed downstream of the boiler furnace wall and the boiler furnace composed of water-cooled pipes, and then passes through the flue to treat the exhaust gas. To flow.

  In the exhaust gas treatment facility, first, fly ash in the combustion exhaust gas is removed by the dust removing device 7 and then the sulfur oxide is removed by the desulfurizing device 8. A dry electrostatic precipitator is generally used as the dust removing device. After dedusting, the combustion exhaust gas removes moisture in the combustion exhaust gas with a moisture removing device 9. At the outlet of the moisture removal facility, the moisture in the combustion exhaust gas is saturated, and the combustion exhaust gas in this state is hereinafter referred to as dry combustion exhaust gas. Then, the dry combustion exhaust gas is sent to the carbon dioxide recovery facility 10, and at this time, the concentration of carbon dioxide in the dry combustion exhaust gas becomes 90% or more. In the carbon dioxide recovery facility 10, the dry combustion exhaust gas from which carbon dioxide has been removed is mixed with nitrogen generated in the oxygen production facility 4, sent to the chimney, and discharged out of the system. As the moisture removing device 9, a shell and tube heat exchanger, a scrubber, or the like can be selected. The carbon dioxide recovery facility 10 can be selected from a method of liquefying using a compressor and a method of separating using a membrane.

  In this embodiment, a part of the combustion exhaust gas (dry combustion exhaust gas) from which moisture has been removed by the moisture removal device 9 after dedusting / desulfurization and the recirculation exhaust gas line 11 for recirculating part of the combustion exhaust gas immediately after dedusting is recycled. And a circulating recirculation exhaust gas line 12. These lines are connected to a line for supplying oxygen from the oxygen production facility 4. These lines are equipment such as piping. The line for supplying oxygen has a plurality of systems capable of supplying oxygen produced by the oxygen production facility to an arbitrary system among the plurality of systems of the recirculation exhaust gas line. The recirculation exhaust gas line 11 and the dry recirculation exhaust gas line 12 extract exhaust gas from at least one or more recirculation gas outlets installed upstream of the flue of the carbon dioxide recovery facility.

  After the exhaust gas in the former line is heated by the heat exchanger 6, the oxygen produced in the oxygen production facility 4 is mixed and sent to the burner 1 and the oxidizing gas supply port 3. On the other hand, after the exhaust gas in the latter line is heated by the heat exchanger 6, a part of the exhaust gas is sent to the coal supply facility 13 and used to convey the pulverized coal after pulverization. The remaining exhaust gas is sent to the dry recirculation exhaust gas supply port 14. The dry recirculated exhaust gas sent to the coal supply facility 13 also has a role of drying the pulverized coal. Moreover, in order to improve the ignitability of pulverized coal, oxygen produced by the oxygen production facility 4 is mixed downstream of the coal supply facility 13.

  Since the oxyfuel boiler circulates the exhaust gas, the amount of gas flowing from the recirculation exhaust gas outlet to the downstream device is smaller than that of the air-fired coal combustion boiler, and there is an advantage that the device can be downsized.

  In order to make the drawing easier to see, the recirculated exhaust gas is supplied only to the burner and supply port on the left side (before the can) in FIG. Actually, it is also supplied to the burner and supply port on the right side of the figure (after the can).

  In this embodiment, the dry recirculation gas is fed from the dry recirculation exhaust gas supply port 14 into the reducing atmosphere region 15 in the boiler furnace 2. That is, since the dry recirculated exhaust gas is put into the reducing atmosphere region 15 in the boiler furnace 2, the dry recirculated exhaust gas supply port 14 is always installed below the oxidizing gas supply port 3. The effect when installed at this position will be described with reference to FIG. In many cases, the burner 1 has a concentric multi-circular tube structure, and in many cases, fuel flows from the center and an oxidant flows around the fuel. In this case, the vicinity of the center of the jet of the burner becomes a reducing atmosphere 22 in excess of fuel, but the surrounding area is locally an oxidizing atmosphere. At this time, when the recirculation gas 24 is mixed with the gas rising in the vicinity of the inner wall surface of the boiler furnace 2, the region 23 to be locally oxidized can be made a reducing atmosphere. By expanding the reduction zone, nitrogen oxides generated from the oxidation zone can be suppressed.

  FIG. 2 is another input configuration diagram of the dry recirculation gas. In FIG. 1, the dry recirculation exhaust gas supply port 14 is installed between the oxidizing gas supply port 3 and the burner. However, if the dry recirculation exhaust gas can be introduced into the reducing atmosphere, a boiler furnace as shown in FIG. A dry recirculation exhaust gas supply port 14 may be provided at the bottom. In this case, since there is only one insertion port, there is an advantage that the manufacturing cost is reduced because the piping related to recirculation becomes one line. The amount of gas to be recirculated is about 60% to 80% of the amount of gas generated in the boiler furnace 2, and the flow rate is enormous. The cost effect is large when it is one system in actual operation.

  FIG. 3 is a diagram showing the relationship between carbon monoxide concentration and nitrogen oxide concentration in the presence of coal particles. Here, as shown in FIG. 3, as an experimental fact, in the presence of coal particles, the generation amount of nitrogen oxide is suppressed in a reducing atmosphere with a high carbon monoxide concentration. For this reason, in the present invention, carbon dioxide is blown into the field of the reducing atmosphere, so that carbon dioxide causes a reduction reaction on the surface of the coal particles and promotes a reaction for generating carbon monoxide. FIG. 4 shows an image of the reduction reaction of carbon dioxide on the coal surface. In a reducing atmosphere with a high carbon monoxide concentration, the reduction reaction tends to proceed.

  Further, since there is no moisture in the dry recirculation exhaust gas, no OH radicals derived from water are generated in the vicinity of the dry recirculation exhaust gas supply port 14. FIG. 5 is a diagram showing a reaction path of nitrogen oxides in a reducing atmosphere. As shown in the reaction path of FIG. 5, OH radicals cause generation of nitrogen oxides. For example, when moisture exists in the dry recirculated exhaust gas, OH radicals are generated from water in a high-temperature gas exceeding 1000 ° C. When OH radicals are present, cyan (HCN) generated from the nitrogen component in coal first becomes CN, then becomes NCO, and finally becomes nitrogen oxide (NO). Therefore, when generation of OH radicals is suppressed, generation of nitrogen oxides is also suppressed.

  In this embodiment, the denitration apparatus is not described. However, even if a denitration apparatus is present in the system, it can be established. The denitration apparatus is generally installed downstream of the heat exchanger 6.

  As described above, an oxygen production facility that separates oxygen from air, a coal supply facility that dry-pulverizes coal, a burner that burns oxygen produced in the oxygen production facility and coal supplied from the coal supply facility, and a burner A boiler with a wall, a flue from the boiler to the chimney that discharges the combustion exhaust gas of the boiler, a carbon dioxide recovery facility that is installed downstream of the flue and separates carbon dioxide from the exhaust, and from the middle of the flue A recirculation exhaust gas facility for extracting a part of the exhaust gas and recirculating it to the boiler, a heat exchange facility for exchanging heat between the flue exhaust gas and the exhaust gas of the recirculation exhaust gas facility, and the oxygen in any system of the recirculation exhaust gas facility Oxygen supply equipment that has multiple systems that can supply oxygen produced by the production equipment, a recirculation gas outlet installed upstream of the flue of the carbon dioxide recovery equipment, and moisture removal that reduces exhaust gas The recirculation exhaust gas facility is a recirculation exhaust gas facility for recirculating the dry exhaust gas dehumidified by the moisture removal facility, and the dry recirculation exhaust gas supply port for flowing the dry exhaust gas into the reducing atmosphere region in the boiler By providing an oxyfuel boiler system characterized by having a dry recirculated exhaust gas from which moisture has been removed is returned to the reducing atmosphere of the boiler furnace. As a result, the carbon dioxide concentration in the reducing atmosphere is increased, and the reduction reaction of the coal particles proceeds. A local oxidation region generated in the burner can also be a reducing atmosphere. When the reduction reaction occurs, the carbon monoxide concentration increases and the nitrogen oxide concentration decreases. Furthermore, since generation | occurrence | production of nitrogen oxide can be suppressed, it becomes possible to respond to coal types having different fuel components (high nitrogen content). Moreover, the cost for denitration can be reduced.

  In addition, oxygen produced in an oxygen production facility that separates oxygen from air and coal supplied from a coal supply facility that dryly pulverizes coal are burned in a boiler, and the exhaust gas from the boiler is dehumidified to produce dry exhaust gas. By the combustion method of the oxyfuel boiler system that allows dry exhaust gas to flow into the reducing atmosphere region in the boiler, the local oxidation region generated by the burner can be made a reducing atmosphere.

  Also, an oxidizing gas supply port for supplying a mixed gas of oxygen produced by the oxygen production facility and combustion exhaust gas generated in the boiler downstream of the burner, upstream of the oxidizing gas supply port, and downstream of the burner By providing the dry recirculation exhaust gas supply port for supplying the dry recirculation exhaust gas, the local oxidation region generated in the burner can also be made a reducing atmosphere.

  In addition, by providing the dry recirculation exhaust gas supply port at the bottom of the boiler, the production cost can be reduced while suppressing the generation of nitrogen oxides.

  In addition, by having a system for returning the dried exhaust gas dehumidified in the moisture removal equipment to the boiler from the dry recirculation exhaust gas supply port and a system for returning it to the coal supply equipment, there is little moisture while suppressing the generation of nitrogen oxides. Therefore, the ability to dry coal in the mill can be increased.

  FIG. 6 is a block diagram for introducing oxygen into the dry recirculation gas. In the oxyfuel boiler of the first embodiment, FIG. 6 shows an embodiment in which oxygen is mixed with the dry recirculated exhaust gas and the exhaust gas is introduced from the dry recirculated exhaust gas supply port 14 into the reducing atmosphere region 15 in the boiler furnace.

  When a detailed chemical reaction analysis based on elementary reaction is performed, oxygen is supplied at a weight ratio of about 50% to 65% for the burner, about 8% to 15% for the exhaust gas for dry recirculation, and about 27 to 35% for the oxidizing gas. When it mixed, the result that the generation amount of nitrogen oxide was suppressed more was obtained. According to this knowledge, the generation amount of nitrogen oxides can be suppressed by adding an appropriate amount of oxygen to the dry recirculated exhaust gas. However, it has also been found that if the amount of oxygen is too large, the combustion gas temperature increases, and a large amount of thermal NOx is generated, resulting in an increase in the amount of nitrogen oxide produced. Accordingly, it is desirable to input an appropriate amount of oxygen using the flow control valve 16 while monitoring the amount of nitrogen oxide generated.

  Thus, by having the oxygen flow rate adjustment valve capable of adjusting the amount of oxygen supplied to the dry recirculated exhaust gas dehumidified by the moisture removal equipment, it is possible to control the suppression of nitrogen oxide generation.

  FIG. 7 is a configuration diagram in which a recirculation gas outlet is installed after desulfurization. In the oxyfuel boiler of the first embodiment, an embodiment in which the gas outlet of the recirculation exhaust gas line 11 is after dedusting / desulfurization is shown in FIG.

  Since the gas after dedusting / desulfurization is recycled, the content of sulfur oxides in the recirculated exhaust gas is small. For this reason, even if the gas reaches the dew point in the recirculated gas pipe, there is almost no sulfuric acid generated due to the sulfur oxide. Sulfuric acid has a strong oxidizing property, and if it is generated, it may corrode the piping. Normally, since the pipe is kept warm so that the dew point is not reached, such an event does not occur. However, the present embodiment provides an essentially safe design. Moreover, if the gas containing sulfur oxides is returned to the reducing atmosphere region 15 in the boiler furnace 2, hydrogen sulfide may be generated to corrode piping on the inner surface of the boiler furnace. Therefore, when using coal with a high sulfur content, it is better to desulfurize the recycle gas.

  As described above, at least one of the plurality of recirculation exhaust gas facilities for recirculating the exhaust gas taken out from the recirculation gas outlet can be disposed downstream of the desulfurization apparatus, thereby suppressing the amount of sulfuric acid generated. it can.

  FIG. 8 shows an embodiment in which the recirculated exhaust gas is taken out from the downstream of the dust removing device 7 in the oxyfuel boiler of the first embodiment, the recirculated exhaust gas line 11 is branched in the middle, and the moisture removing device 17 is attached to one line. . When the moisture removal device 17 in the middle of the recirculation exhaust gas line and the moisture removal device 9 just before the recovery of carbon dioxide are separated as in this embodiment, the dry recirculation gas returned to the boiler furnace is required. The residual moisture ratio and the residual moisture ratio required by the carbon dioxide recovery facility 10 can be individually controlled. In order to make the carbon dioxide recovery facility 10 more efficient in recovering carbon dioxide, it is necessary to supply exhaust gas with as little water as possible. Therefore, the water removal device 9 immediately before the recovery of carbon dioxide is a high-performance device. On the other hand, the water removal device 17 in the middle of the recirculation exhaust gas line may have lower performance than the water removal device 9 immediately before the recovery of carbon dioxide. Thereby, the production cost of the water removal device 17 in the middle of the recirculation exhaust gas line can be kept lower than that of the water removal device 9 immediately before the recovery of carbon dioxide. Further, since the moisture in the exhaust gas upstream is removed by the moisture removing device 17 in the middle of the recirculated exhaust gas line, the processing capacity of the moisture removing device 9 immediately before the recovery of carbon dioxide can be reduced.

  In this embodiment, the recirculated exhaust gas is taken out from between the dust removal device and the desulfurization device, but may be anywhere as long as it is downstream of the dust removal device. For example, it may be downstream of the desulfurizer.

  Thus, there are a plurality of water removal facilities, one water removal facility is disposed in the recirculation exhaust gas facility that returns the exhaust gas from the recirculation exhaust gas outlet to the boiler furnace, and the other water removal facility is the recirculation gas. By disposing in the flue downstream from the take-out port, the residual moisture ratio required for the dry recirculation gas and the residual moisture ratio required for the carbon dioxide recovery facility 10 can be individually controlled. Moreover, the manufacturing cost of the water removal apparatus 17 in the middle of the recirculation exhaust gas line can be kept lower than that of the water removal apparatus 9 immediately before the recovery of carbon dioxide.

  In the oxyfuel boiler of the first embodiment, FIG. 9 shows an embodiment in which a line 19 for feeding dry recirculated exhaust gas to a mill 18 in the coal supply facility 13 and a line 20 for bypassing it are installed. Since the particle size of coal after being pulverized by the mill 18 is small (about several tens of microns), it is necessary to consider the risk of ignition and explosion. In this embodiment, oxygen and dry recirculation exhaust gas are mixed in advance in the dry recirculation exhaust gas bypass line 20 and then mixed with pulverized coal. The risk of an explosion increases if there is any ignition source that is a mixture of pulverized coal and high-concentration oxygen. In this embodiment, oxygen is not directly blown into pulverized coal, but a gas mixed with oxygen and dry recirculated exhaust gas is blown to reduce the risk of ignition and explosion.

  Thus, the risk of ignition / explosion of pulverized coal can be reduced by having the equipment for the dry recirculation exhaust gas to bypass the coal supply equipment and the equipment for supplying oxygen to the bypass.

  FIG. 10 shows an embodiment in which the combustion exhaust gas generated in the combustion facility 21 provided outside the system in the oxyfuel boiler of the first embodiment is charged into the boiler furnace 2. For example, the combustion exhaust gas generated from the other combustion equipment 21 that burns the waste generated from the boiler site or the local waste is put into the boiler furnace 2. As in the present embodiment, the composition of the exhaust gas generated from the combustion equipment 21 provided outside the system is mostly composed of carbon dioxide and moisture. Therefore, when the moisture is removed, the dry recirculation gas as shown in Embodiment 1 is used. It is possible to supply the same exhaust gas. Since the exhaust gas generated from the combustion equipment 21 provided outside the system is high temperature, after removing heat with a heat exchanger, moisture is removed, and the reducing atmosphere in the boiler furnace is removed from the dry recirculation exhaust gas supply port 14 of the boiler furnace 2. In the area of.

  Thus, it has a combustor of another system, an exhaust gas transport facility for transporting combustion exhaust gas generated in the combustor of another system, and a moisture removal facility for removing moisture from the combustion exhaust gas. By supplying the flue gas from which the moisture was removed to the recirculated exhaust gas supply port, the exhaust gas from other facilities other than the dry recirculated exhaust gas of the own equipment was also generated by the burner. The local oxidation region can also be a reducing atmosphere.

The block diagram of the oxyfuel boiler system of this invention. Another charging configuration diagram of dry recirculation gas. Relationship between carbon monoxide concentration and nitrogen oxide concentration in the presence of coal particles. Image of carbon dioxide reduction on the surface of coal particles in a reducing atmosphere. Reaction pathway of nitrogen oxides in a reducing atmosphere. The block diagram which introduce | transduces oxygen into dry recirculation gas. The block diagram which installed the extraction port of the recirculation gas after desulfurization. The block diagram which branched the recirculation exhaust gas line in the middle, and attached the moisture removal apparatus to one line. The block diagram which bypassed dry recirculation gas partially in the coal supply equipment, and supplied oxygen to the bypass line. The block diagram which supplies the exhaust gas of the combustor of another system to an oxyfuel boiler. The figure which shows the position of a dry recirculation waste gas supply port.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Burner 2 Boiler furnace 3 Oxidation gas supply port 4 Oxygen production facility 5 Chimney 6 Heat exchanger 7 Dust removal device 8 Desulfurization device 9, 17 Moisture removal device 10 Carbon dioxide recovery facility 11 Recirculation exhaust gas line 12 Dry recirculation exhaust gas line 13 Coal supply facility 14 Dry recirculation exhaust gas supply port 15 Reducing atmosphere region 16 Flow rate control valve 22 Reducing atmosphere 23 exceeding fuel Locally oxidizing region 24 Recirculating gas

Claims (11)

An oxygen production facility that separates oxygen from the air;
Coal supply equipment for drying and crushing coal;
A burner for burning the oxygen produced in the oxygen production facility and the coal supplied from the coal supply facility;
A boiler with the burner on the wall;
A flue from the boiler to the chimney that discharges the combustion exhaust gas of the boiler;
A carbon dioxide recovery facility installed downstream of the flue and separating carbon dioxide from the exhaust gas;
A recirculation exhaust gas facility for extracting a part of exhaust gas from the middle of the flue and recirculating it to the boiler;
A heat exchange facility for exchanging heat between the flue exhaust gas and the recirculation exhaust gas facility;
An oxygen supply facility having a plurality of systems capable of supplying oxygen produced by the oxygen production facility to an arbitrary system of the recirculation exhaust gas facility;
A recirculation gas outlet installed upstream of the flue of the carbon dioxide recovery facility;
A water removal facility for dehumidifying the exhaust gas,
The recirculation exhaust gas facility is a recirculation exhaust gas facility that recirculates dry exhaust gas dehumidified by the moisture removal facility,
An oxyfuel boiler system having a dry recirculation exhaust gas supply port for allowing the dry exhaust gas to flow into a reducing atmosphere region in the boiler. The oxyfuel boiler system of claim 1,
An oxidizing gas supply port for supplying a mixed gas of oxygen produced in the oxygen production facility and combustion exhaust gas generated in the boiler downstream of the burner;
An oxyfuel boiler system comprising a dry recirculation exhaust gas supply port for supplying the dry exhaust gas upstream from an oxidizing gas supply port and downstream from a burner. The oxyfuel boiler system of claim 1,
An oxyfuel boiler system having a dry recirculation exhaust gas supply port at the bottom of the boiler. The oxyfuel boiler system of claim 1,
An oxyfuel boiler system comprising: a system for returning dry exhaust gas dehumidified by a moisture removal facility to a boiler from a dry recirculation exhaust gas supply port; and a system for returning to a coal supply facility.   2. The oxyfuel boiler system according to claim 1, further comprising an oxygen flow rate adjustment valve capable of adjusting an amount of oxygen supplied to the dry exhaust gas dehumidified by the water removal equipment.   2. The oxyfuel boiler system according to claim 1, wherein at least one of the plurality of recirculation exhaust gas facilities for recirculating the exhaust gas extracted from the recirculation gas outlet is disposed downstream of the desulfurization apparatus. Oxy-combustion boiler system. The oxyfuel boiler system of claim 1,
Having a plurality of water removal facilities,
One water removal facility is disposed in the recirculation exhaust gas facility for returning exhaust gas from the recirculation exhaust gas outlet to the boiler furnace,
The other water removal facility is disposed in the flue downstream of the recirculation gas outlet, and is an oxyfuel boiler system. The oxyfuel boiler system according to claim 4,
A facility for dry recirculated exhaust gas to bypass the coal supply facility;
A facility for supplying oxygen to the bypass;
An oxyfuel boiler system comprising: The oxyfuel boiler system of claim 1,
A separate combustor,
An exhaust gas transport facility for transporting the flue gas generated in the combustor of the different system;
A moisture removal facility for removing moisture from the combustion exhaust gas,
The oxyfuel boiler system, wherein the exhaust gas transportation facility supplies combustion exhaust gas generated in the separate combustor and having moisture removed to the dry recirculation exhaust gas supply port. An oxygen production facility that separates oxygen from the air;
Coal supply equipment for drying and crushing coal;
A burner for burning the oxygen produced in the oxygen production facility and the coal supplied from the coal supply facility;
A boiler with the burner on the wall;
An oxidizing gas supply port for supplying a mixed gas of oxygen produced in the oxygen production facility and combustion exhaust gas generated in the boiler downstream of the burner;
A flue from the boiler to the chimney that discharges the combustion exhaust gas of the boiler;
A carbon dioxide recovery facility installed downstream of the flue and separating carbon dioxide from the exhaust gas;
A recirculation exhaust gas facility for extracting a part of exhaust gas from the middle of the flue and recirculating it to the boiler;
A heat exchange facility for exchanging heat between the flue exhaust gas and the recirculation exhaust gas facility;
An oxygen supply facility having a plurality of systems capable of supplying oxygen produced by the oxygen production facility to an arbitrary system of the recirculation exhaust gas facility;
A recirculation gas outlet installed upstream of the flue of the carbon dioxide recovery facility;
A water removal facility for dehumidifying the recirculated exhaust gas,
The recirculation exhaust gas facility is a recirculation exhaust gas facility that recirculates dry exhaust gas dehumidified by the moisture removal facility,
An oxyfuel boiler system comprising a dry recirculation exhaust gas supply port for allowing the dry exhaust gas to flow into the boiler upstream from the oxidizing gas supply port and downstream from the burner. Combusting the oxygen produced in the oxygen production facility that separates oxygen from the air and the coal supplied from the coal supply facility that dry-pulverizes the coal in a boiler,
Dehumidifying the combustion exhaust gas of the boiler to produce dry exhaust gas,
A combustion method for an oxyfuel boiler system, wherein the dry exhaust gas is caused to flow into a reducing atmosphere region in the boiler.

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