Combustion facility with apparatus for separating and recovering co2 in combustion exhaust gas

Abstract

To provide a technology configuration which can prevent intrusion of outside air into an apparatus by putting the inside of the apparatus under negative pressure, and which separates and recovers CO2 in high concentration, while curbing energy consumption during recovery, by increasing CO2 concentration in combustion exhaust gas.SOLUTION: Combustion facilities 1 comprise: a burner reactor 10; a mixed gas supply part 30 for supplying mixed gas in which circulated exhaust gas of combustion exhaust gas from the burner reactor 10 and oxygen are mixed together; a carbon dioxide recovery apparatus 16 for separating and recovering carbon dioxide from the combustion exhaust gas from the burner reactor 10; and an air inflow prevention part for preventing the inflow of air from the outside of the combustion facilities.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a combustion facility equipped with a CO2 separation and capture device that separates and captures CO2 from exhaust gas emitted from, for example, a biomass power generation facility, a waste treatment facility, or a garbage incineration facility. [Background technology]

[0002] In recent years, separation and capture of CO2 from combustion exhaust gas in biomass power generation and waste treatment has become important in order to achieve carbon neutral and carbon negative.

[0003] Demonstration tests are being conducted to separate and capture CO2 contained in the flue gas from a stoker furnace using chemical absorption, and use it for algae cultivation, etc. When air is used as the combustion oxidant, chemical absorption is used as a method to separate and capture CO2 from low-pressure, low-CO2 concentration flue gas. In the chemical absorption method, amines, which have a high low CO2 absorption capacity, combine with CO2 to separate CO2, but a large amount of energy is required to regenerate the CO2. Oxygen-enriched combustion has been proposed as a method to increase the CO2 concentration in the flue gas and capture CO2 with high efficiency.

[0004] Stoker furnaces that employ oxygen-enriched combustion are disclosed, for example, in Patent Document 1 and Patent Document 2. There is no mention of controlling the carbon dioxide concentration in the combustion exhaust gas and separating and capturing carbon dioxide. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-331192 A [Patent Document 2] JP 2006-242490 A Summary of the Invention [Problem to be solved by the invention]

[0006] In cryogenic separation, if the CO2 concentration in the gas is low, the energy consumption is very large. In order to separate and capture CO2 using cryogenic separation alone, high concentration CO2 is required. In addition, outside air easily enters biomass power plants and waste treatment facilities through the rotary valves and chemical feed fans at the bottom of the bag filters. Although this does not interfere with normal operation, the intrusion of outside air during oxygen combustion can cause a decrease in the CO2 concentration in the combustion exhaust gas. For this reason, it is necessary to prevent outside air from entering the inside of the equipment by creating negative pressure inside the combustion furnace and other equipment.

[0007] The present disclosure provides a technical configuration for increasing the CO2 concentration in combustion exhaust gas and separating and capturing CO2 at a high concentration while reducing energy consumption during separation and capture. [Means for solving the problem]

[0008] The combustion facilities (A1, A2, A3) of the present disclosure include: A combustion furnace (10); a mixed gas supply unit (30) for supplying to the combustion furnace (10) a mixed gas obtained by mixing a circulating exhaust gas of the combustion exhaust gas from the combustion furnace (10) and oxygen gas; a carbon dioxide recovery device (16) that separates and recovers carbon dioxide from the combustion exhaust gas from the combustion furnace (10); The combustion facility is provided with an air inflow prevention section (121, 131, 151) for preventing the inflow of air from outside the facility.

[0009] The combustion facilities (A1, A2, A3) include Carbon dioxide concentration measuring devices (S1, S2) for measuring the CO2 concentration in the combustion exhaust gas may be provided at any position in the combustion furnace (11), the boiler (12), the heat exchanger (13), the exhaust gas filtration device (15), or the combustion exhaust gas piping (L1, L2, L3). The concentration of CO2 in the exhaust gas is, for example, 80% or more, and preferably 90% or more. The combustion facility (1) comprises: The system may include a mixed gas control unit (31) that controls the flow rate and oxygen concentration of the mixed gas supplied from the mixed gas supply unit (30) so that the CO2 concentration in the combustion exhaust gas measured by the carbon dioxide concentration measuring devices (S1, S2) is 80% or more, preferably 90% or more.

[0010] The combustion furnace (10) may be supplied with biomass and / or waste as fuel.

[0011] The mixed gas supply section (30) may prepare the mixed gas so that the mixed gas has an oxygen concentration of 21%. The oxygen gas supply unit (17) may include an oxygen gas storage unit, a liquid oxygen storage unit, an expansion valve, piping, a compressor, a high-concentration oxygen production unit (which may include an air separation unit), etc. The concentration of the oxygen gas is 99.0% or more, and preferably 99.8% or more.

[0012] The combustion facilities (A1, A2, A3) include The circulation exhaust gas flow path (L3) may be provided with a circulation exhaust gas flow control valve (V1) (which may include a flow meter) that adjusts the flow rate of the circulation exhaust gas, and the oxygen gas supply path (L4) may be provided with an oxygen flow control valve (V4) (which may include a flow meter) that adjusts the flow rate of the oxygen gas. The mixed gas control section (31) At least one of the circulating exhaust gas flow control valve (V1: may be a damper) and the oxygen flow control valve (V4: may be a damper) may be controlled so that the CO2 concentration measured by the carbon dioxide concentration measuring device (S1, S2) is 80% or more, preferably 90% or more.

[0013] The combustion facilities (A1, A2, A3) include The mixed gas flow path (L5) may be provided with an oxygen concentration measuring device (S5) for measuring the oxygen concentration of the mixed gas supplied to the combustion furnace (10). The mixed gas control unit (31) At least one of the circulation exhaust gas flow rate control valve (V1) and the oxygen flow rate control valve (V4) may be controlled so that the oxygen concentration measured by the oxygen concentration measuring device (S5) becomes 18 to 30%, preferably 21%. The mixed gas control unit (31) may control the circulating exhaust gas flow control valve (V1) (which may be an EGR damper) and the oxygen flow control valve (V4) (which may be a damper) based on information inside the combustion furnace (temperature, pressure, oxygen concentration, etc.) and the oxygen concentration of the mixed gas of the circulating exhaust gas and high-concentration oxygen.

[0014] The air inflow prevention part (151) may be one selected from a double damper, a slide gate, and a butterfly valve provided in an exhaust gas filtering device (15) to which the combustion exhaust gas from the combustion furnace (10) is supplied. The air inflow prevention part (131) may be one selected from a double damper, a slide gate, and a butterfly valve provided in a heat exchanger (13) to which the combustion exhaust gas from the combustion furnace (10) is supplied. The air inflow prevention part (121) may be one selected from a double damper, a slide gate, and a butterfly valve provided in a boiler (12) to which the combustion exhaust gas from the combustion furnace (10) is supplied. By adopting one type selected from a double damper, a slide gate, and a butterfly valve at the bottom of an exhaust gas filtering device (e.g., a bag filter) or at the bottom of a boiler (12) or a heat exchanger (e.g., an economizer), it is possible to prevent outside air from entering the device.

[0015] The air inflow prevention portion is The intrusion of air into the combustion furnace (10) may be suppressed or prevented by supplying gas that has been treated for carbon dioxide capture to a fuel introduction section (eg, a supply hopper 101) of the combustion furnace (10).

[0016] The air inflow prevention portion is The configuration may be such that gas that has been treated to capture carbon dioxide is supplied to the main ash chute section (102), which is a passage for sending ash from the combustion furnace (10) to the outside, thereby suppressing or preventing outside air from entering the combustion furnace (10) through the main ash chute section (102).

[0017] The air inflow prevention portion is A configuration may be adopted in which gas that has been treated for carbon dioxide capture is supplied instead of air to the points (201, 202, 203, 204) where air is purged into the combustion furnace (10), thereby suppressing or preventing air from entering the combustion furnace (10).

[0018] The combustion facilities (A1, A2, A3) include The system may further include an agent supplying section (14) that supplies an agent to the combustion exhaust gas flow passage (L1) upstream of the exhaust gas filtration device (15) by using the carbon dioxide recovered by the carbon dioxide recovery device (16). By using high-concentration CO2 gas recovered by the carbon dioxide recovery device (16) or liquid carbon dioxide as the drug supply gas, it is possible to prevent outside air from entering the device. The combustion facilities (A1, A2, A3) include The system may further include an agent supplying section (14) that supplies an agent to the combustion exhaust gas flow path (L1) upstream of the exhaust gas filtration device (15) by using the circulating exhaust gas from which moisture has been removed.

[0019] The combustion facilities (A1, A2, A3) include The oxygen may be preheated by waste heat from the heat exchanger (13) (heat exchange section 132).

[0020] The combustion facilities (A1, A2, A3) include The circulating exhaust gas in the circulating exhaust gas flow path (L3) may be preheated by waste heat (heat exchange section 132) of the heat exchanger (13).

[0021] The combustion facilities (A1, A2, A3) include The circulation exhaust gas in the circulation exhaust gas flow path (L3) may be configured to dehumidify the same.

[0022] The carbon dioxide capture unit (16) may separate carbon dioxide at a high concentration from the combustion exhaust gas by one or more methods selected from cryogenic separation, pressure swing adsorption, membrane separation, and physical adsorption. In biomass power plants and waste treatment facilities, the oxidant is replaced by oxygen and the combustion exhaust gas is circulated (by applying oxyfuel combustion technology), which makes it possible to increase the CO2 concentration in the combustion exhaust gas to 80% or more, preferably 90% or more. This also makes it possible to adopt an inexpensive CO2 separation and capture process.

[0023] The combustion facilities (A1, A2, A3) include There may be a chimney (300) to which the gas is delivered after being treated in the carbon dioxide capture unit. The combustion facilities (A1, A2, A3) include The gas after being treated in the carbon dioxide recovery unit may be sent to the gas inlet of the combustion furnace (10). The combustion facilities (A1, A2, A3) include A control unit may be provided to control the amount of gas sent to the chimney (300) and the amount of gas sent to the gas inlet of the combustion furnace (10).

[0024] Examples of the "combustion furnace" include a traveling stoker and a stepped stoker. Examples of "fuel" include garbage (municipal garbage, household garbage), industrial waste, and biomass. Biomass includes waste-based biomass (livestock waste, food waste, waste paper, pulp mill effluent, sewage sludge, human waste sludge, construction wood, sawmill residues, etc.), unused biomass (rice straw, wheat straw, rice husks, forest residues, etc.), resource crops (sugar resources, starch resources, oil resources), willow, poplar, switchgrass, etc.).

[0025] (effect) (1) It is possible to prevent outside air from entering through the rotary valve at the bottom of the bag filter and the chemical injection fan, thereby increasing the CO2 concentration in the combustion exhaust gas. (2) When using cryogenic separation to increase the concentration of CO2, if the concentration of CO2 in the gas is low, the energy consumption becomes very large. This disclosure makes it possible to increase the CO2 concentration in the combustion exhaust gas emitted from a biomass or waste combustion furnace, and to realize a CO2 separation and capture process using only cryogenic separation without using chemical absorption. (3) CO2 can be captured at high concentrations (99.5% or more, liquefied carbon dioxide standard JIS K 1106-1990) to produce liquefied carbon dioxide. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a diagram showing a combustion facility of a first embodiment. [Diagram 2] FIG. 13 is a diagram showing a combustion facility of a second embodiment. [Diagram 3] FIG. 11 is a diagram showing a combustion facility according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Several embodiments of the present invention will be described below. The embodiments described below are merely examples of the present invention. The present invention is not limited to the following embodiments, and includes various modified forms that are implemented within the scope of the present invention.

[0028] (Embodiment 1) FIG. 1 shows a combustion facility A1. The combustion furnace 10 is a stoker type combustion furnace. A mixed gas of oxygen gas and circulating exhaust gas is used as an oxidizing agent supplied to the combustion furnace 10. The mixed gas is controlled so that the oxygen concentration is 18 to 30%, preferably 21%. This control will be described later.

[0029] The combustion exhaust gas combusted in the combustion furnace 10 is sent to a boiler 12 and then sent to an economizer 13. A concentration measuring device S1 for measuring the carbon dioxide concentration in the combustion exhaust gas is installed inside the combustion furnace 11. In addition to the carbon dioxide gas, measuring devices for measuring the NOx and oxygen gas concentrations may also be installed inside the combustion furnace 11. A temperature measuring device and a pressure measuring device may also be installed. As information inside the combustion furnace 10 , various data such as the measured temperature, pressure, oxygen concentration, and carbon dioxide concentration are sent to a mixed gas control unit 31 .

[0030] Pipe L1 leading from the economizer 13 is connected to a bag filter 15. Pipe L2 leading from the bag filter 15 is provided with a suction pump 21, which sends the combustion exhaust gas from which dust has been removed by the bag filter 15 to the carbon dioxide capture device 16. Pipe L3 branching from pipe L2 is installed to send the combustion exhaust gas from which dust has been removed to the mixed gas supply unit 30 as a circulating exhaust gas. Pipe L2 is provided with a valve V2, which opens when the carbon dioxide concentration in the combustion exhaust gas (the carbon dioxide concentration in the combustion exhaust gas derived from the bag filter 15, for example, a value measured by a carbon dioxide concentration measuring device S2) is a predetermined value or higher (for example, 80% or higher, preferably 90% or higher), and sends the combustion exhaust gas to the carbon dioxide recovery device 16.

[0031] Pipe L3 branching off from pipe L2 is provided with a carbon dioxide concentration measuring device S2 and a valve V1 (sometimes referred to as an EGR damper), and the amount of circulating exhaust gas sent to the mixed gas supply section 30 can be adjusted while measuring the carbon dioxide concentration in the combustion exhaust gas.

[0032] In addition, pipe L1 is joined with pipe L5 for supplying high-concentration carbon dioxide gas sent from carbon dioxide capture device 16. Pipe L5 is provided with a suction pump 23, and can send a predetermined amount of chemical agent supplied from chemical agent input unit 14 to pipe 1 at the same time as sending high-concentration carbon dioxide gas. The high-concentration carbon dioxide gas and chemical agent are joined with the combustion exhaust gas in pipe L1 and sent to bag filter 15.

[0033] Air inflow prevention sections 151, 121, 131 having a double damper structure are provided below the bag filter 15, the boiler 12, and the economizer 13, respectively, to prevent outside air from entering the device.

[0034] The combustion exhaust gas sent to the carbon dioxide capture device 16 is subjected to carbon dioxide capture processing and then sent to the chimney 300 via the pipe L8. In the pipe L8, a branch pipe L81 branches off upstream of the chimney 300 and is connected to an introduction section (e.g., a garbage input duct) of the fuel inlet of the combustion furnace 10, the air inflow prevention section 121 of the boiler 12, the air inflow prevention section 131 of the economizer 13, and the air inflow prevention section 151 of the bag filter 15. The pipes to each air inflow prevention section may be branch pipes branching off from the branch pipe L81. The pipe L8 and the branch pipe L81 are provided with valves V9, V10, V11, V12, V13, and V14, respectively. A control unit (not shown) controls the opening, closing, and opening adjustment of the valves V9, V10, V11, V12, V13, and V14 based on the state of the combustion furnace 10 (temperature, pressure, oxygen concentration, etc.), thereby controlling the flow rate of gas sent to the combustion furnace 10. By sending the gas after carbon dioxide capture processing to the introduction section 101 at the fuel inlet of the combustion furnace 10, it is possible to prevent outside air from entering the furnace through gaps in the fuel such as garbage. Also, by sending the gas after carbon dioxide capture processing to each of the air inflow prevention sections 121, 131, and 151, it is possible to more effectively prevent outside air from entering.

[0035] In addition, by supplying gas after carbon dioxide recovery processing to the main ash chute section 102, which is a passage for sending ash from the combustion furnace 10 to the outside, it is possible to suppress or prevent outside air from entering the combustion furnace 10 through the main ash chute section 102.

[0036] In addition, by supplying gas after carbon dioxide capture treatment instead of air to the purge sections 201, 202 of the nozzle tube stand and the level sensor purge sections 203, 204 at the locations where air is purged into the combustion furnace 10, it is possible to suppress or prevent air from entering the combustion furnace 10. The nozzle is a nozzle that sprays urea or filtrate into the inside of the combustion furnace 10.

[0037] The oxygen gas supply unit is a high-concentration oxygen production device 17. The concentration of the oxygen gas supplied is 99.0% or more, preferably 99.8% or more. The pipe L4 is connected to the high-concentration oxygen production device 17 and sends the high-concentration oxygen gas to the mixed gas supply unit 30. The pipe L4 is provided with a suction pump 24, an oxygen concentration measurement device S4, and a valve V4, and the flow rate of the high-concentration oxygen gas can be controlled while referring to the oxygen concentration measured by the oxygen concentration measurement device S4. The pipe L4 is connected to the economizer 13 and has a route configured to preheat the oxygen gas to a predetermined temperature in the heat exchanger 132 of the economizer 13 and then connect it to the mixed gas supply unit 30, and a route that bypasses the economizer 13 (bypass pipe L7) and sends it directly to the mixed gas supply unit 30. A valve V6 (sometimes referred to as a bypass damper) is provided in the bypass pipe L7 so that the presence or absence of preheating can be switched to one of the routes depending on the state of the combustion furnace 10, the temperature of the circulating exhaust gas, the state of the economizer 13, etc. A thermometer S6 for measuring the temperature of high-concentration oxygen is provided in pipe L4 downstream of bypass pipe L7. Based on the temperature of high-concentration oxygen measured by thermometer S6, valve V6 is opened, closed, its opening degree is adjusted, and other controls are performed to control the amount of high-concentration oxygen gas sent to heat exchanger 132 of economizer 13 for preheating and the amount of high-concentration oxygen gas bypassed without preheating.

[0038] The mixed gas supply unit 30 is where the pipes L3 and L4 join together, mixes the circulating exhaust gas with the high-concentration oxygen gas, and sends it to the pipe L6. The mixed gas supply unit 30 may be configured with a buffer tank, a spiral piping structure, or the like. The pipe L6 is led out from the mixed gas supply unit 30 and connected to a plurality of predetermined locations in the combustion furnace 10, and functions as a pipe for sending the mixed gas to each of the locations. An oxygen concentration measuring device S5 and a suction pump 25 are provided in the pipe L6, and the flow rate of the mixed gas can be controlled by referring to the oxygen concentration measured by the oxygen concentration measuring device S5.

[0039] The mixed gas control unit 31 controls at least one of the valve V1 in the pipe L3 and the valve V4 (sometimes referred to as an O2 damper) in the pipe L4 so that the oxygen concentration measured by the oxygen concentration measuring device S5 is 18 to 30%, preferably 21%.

[0040] The mixed gas control unit 31 may control the valve V1 (EGR damper) and the valve V4 (O2 damper) based on information inside the combustion furnace (temperature, pressure, oxygen concentration, etc.), the combustion exhaust gas (EGR gas sent to the mixed gas supply unit 30 through piping L3), and the oxygen concentration of the high-concentration oxygen mixed gas sent from the high-concentration oxygen production device 17 (oxygen concentration measured by the oxygen concentration measuring device S5).

[0041] (Embodiment 2) The combustion apparatus A2 of the second embodiment has a configuration in which a dehumidification tower 201 is provided in the pipe L3 of the first embodiment. 2 dehumidifies the circulating exhaust gas (combustion exhaust gas, EGR gas). Note that the same reference numerals have the same functions, so the description will be omitted.

[0042] (Embodiment 3) The combustion device A3 of the third embodiment has a configuration in which the pipe L3 is connected to the heat exchanger 132 in the first embodiment. 3 is connected to a heat exchanger 132, and preheats the circulating exhaust gas (combustion exhaust gas, EGR gas). Note that the same reference numerals have the same functions, and therefore the description thereof will be omitted. Pipe L4 may or may not be preheated by heat exchanger 132, but it is preferable that it is preheated. Also, dehumidification tower 201 may or may not be present, but it is preferable that it is present. In Fig. 3, pipe L8 to chimney 300, branch pipe L81, valves V9, V10, V11, V12, V13, V14, etc. are omitted.

[0043] (Another embodiment) (1) As the accompanying gas for introducing the agent, the circulating exhaust gas branched off from the pipe L3 may be used instead of the high-concentration carbon dioxide gas sent from the carbon dioxide capture device 16. In this case, it is preferable to use the dehumidified circulating exhaust gas. (2) The mixed gas control unit 31 may control at least one of the valves V1 and V4 so that the CO2 concentration measured by the carbon dioxide concentration measuring devices S1, S2 is 80% or more, and preferably 90% or more. (3) The mixed gas control unit 31 may control at least one of the valves V1 and V4 so that the oxygen concentration measured by the oxygen concentration measuring device S5 is 21% and the CO2 concentrations measured by the carbon dioxide concentration measuring devices S1 and S2 are 80% or more, preferably 90% or more. (4) Although air inflow prevention sections 151, 121, and 131 having a double damper structure were provided at the bottom of the bag filter 15, the boiler 12, and the economizer 13, respectively, a slide gate or a butterfly valve may be used instead of the double damper structure. (5) Carbon dioxide capture device 16 may be configured using one or more types selected from cryogenic separation, pressure swing adsorption, membrane separation, and physical adsorption. [Explanation of symbols]

[0044] 1. Combustion facilities 10 Combustion furnace 13 Economizer 15 Bag filter 16 Carbon dioxide capture equipment 30 Mixed gas supply unit 121 Air inflow prevention part 101 Introduction 102 Main Ash Chute 131 Air inflow prevention part 151 Air inflow prevention part 201 Purge section of nozzle pipe stand 202 Purge section of nozzle pipe stand 203 Level sensor purge section 204 Level sensor purge section

Claims

1. A combustion furnace; a mixed gas supply unit that supplies a mixed gas obtained by mixing oxygen and a circulating exhaust gas from the combustion furnace to the combustion furnace; A carbon dioxide recovery device that separates and recovers carbon dioxide from the combustion exhaust gas from the combustion furnace; A combustion facility comprising an air inflow prevention section for preventing the inflow of air from outside the combustion facility.

2. The combustion facility according to claim 1 , wherein the combustion furnace is supplied with biomass and / or waste as fuel.

3. The combustion facility according to claim 1, wherein the mixed gas supply unit prepares the mixed gas so that the mixed gas has an oxygen concentration of 18 to 30%.

4. The combustion facility according to claim 1 , wherein the air inflow prevention unit is one selected from a double damper, a slide gate, and a butterfly valve provided in an exhaust gas filtration device to which the combustion exhaust gas from the combustion furnace is supplied.

5. The combustion facility according to claim 1 , wherein the air inflow prevention unit is one selected from a double damper, a slide gate, and a butterfly valve provided in a heat exchanger to which the combustion exhaust gas from the combustion furnace is supplied.

6. The combustion facility according to claim 1 , further comprising an agent supplying unit that supplies an agent to the combustion exhaust gas flow furnace using the carbon dioxide captured by the carbon dioxide capture device.

7. 10. The combustion facility of claim 1, wherein the oxygen is preheated by waste heat from a heat exchanger.

8. The combustion facility according to claim 1 , wherein the carbon dioxide capture unit separates carbon dioxide from the combustion exhaust gas by one or more methods selected from cryogenic separation, pressure swing adsorption, membrane separation, and physical adsorption.

9. The air inflow prevention portion is The configuration is such that the intrusion of air into the combustion furnace is suppressed or prevented by supplying gas that has been treated for carbon dioxide capture to one or more of the fuel introduction section, the bottom ash chute section, and the air purging section of the combustion furnace. The combustion facility of claim 1.

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