Method, system and application for treating gasification fine slag

Abstract

The present invention relates to the technical field of coal chemical engineering, and discloses a method, a system and an application for treating gasification fine slag. The method includes: (1) dehydrating and crushing the gasification fine slag to obtain gasification fine slag powder; (2) contacting the gasification fine slag powder with oxygen for combustion to obtain flue gas and ash; (3) returning part of the flue gas to (1) to carry the gasification fine slag powder to contact with oxygen for combustion; before combustion, performing elemental analysis on the gasification fine slag powder to determine the content of each element and the ratio of the content of each element in the gasification fine slag powder; according to the elemental content and ratio of the gasification fine slag powder and the feed rate, adjusting the inlet amount of the flue gas so that the oxygen concentration during combustion is 30-50 vol%, and the excess air coefficient is 1.1-1.2. This method can ensure that the gasification fine slag is in an oxygen-enriched atmosphere during combustion, enabling its stable and sufficient combustion, as well as rapid and large-scale treatment, collecting carbon dioxide and water, reducing carbon emissions, and saving water resources.

Description

Technical Field

[0001] The present invention relates to the technical field of coal chemical industry, and specifically relates to a method, a system and an application for treating gasification fine slag. Background Art

[0002] The large-scale popularization and utilization of coal gasification technology have led to an increasing reserve and production of gasification fine slag, resulting in serious waste of resources and land, and severely restricting the sustainable development of coal chemical enterprises. However, due to the excessively high loss on ignition of gasification fine slag and its inability to meet the requirements of building admixture raw materials, currently, gasification fine slag is mainly treated by landfill, with poor volume reduction effect and great waste of energy. At the same time, gasification fine slag contains a large amount of moisture, and simple landfill treatment will also cause waste of water resources. Moreover, during the landfill process, due to non-standard or imperfect anti-seepage and anti-dust measures, secondary pollution is extremely likely to occur.

[0003] Existing processes propose to mix gasification fine slag with coal in a low ratio and send it into a pulverized coal boiler or a circulating fluidized bed, and the combustible part in the gasification fine slag is burned and reused through high temperature.

[0004] CN113566230A discloses a method and a system for directly co-firing gasification fine slag in a pulverized coal boiler, mainly by using a pressurized pumping device and a secondary atomization device to directly introduce the gasification fine slag into the high-temperature area of the furnace, and relying on the high-temperature and high-mixing-intensity gas flow in the furnace to achieve the rapid diffusion and combustion of the gasification fine slag in the flue gas.

[0005] CN113028418A discloses a treatment system and method for co-firing gasification fine slag in a circulating fluidized bed boiler, and proposes to dry the gasification fine slag by using a feeding and drying device and send it into the circulating fluidized bed for co-firing with coal to achieve the treatment of gasification fine slag and water saving, energy saving and efficiency increase of the system.

[0006] Although the above methods can solve the problems of difficult treatment of gasification fine slag and energy waste, due to the huge reserve and annual output of gasification fine slag in China, and the small treatment volume of co-firing with coal in a low ratio, it is impossible to achieve the rapid and large-scale treatment of gasification fine slag. Moreover, the co-firing of gasification fine slag and coal will also bring carbon dioxide emissions, pollute the environment, and the obtained ash residue has a high carbon content, so it is impossible to efficiently treat gasification fine slag. Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems existing in the prior art, such as the inability to achieve the rapid and large-scale disposal of gasification fine slag and carbon dioxide emissions, and to provide a method, a system and an application for treating gasification fine slag. This method can enable the stable and full combustion of gasification fine slag, rapid and large-scale treatment, collect carbon dioxide and water, and reduce emissions.

[0008] To achieve the above object, a first aspect of the present invention provides a method for treating gasification fine slag, characterized in that the method includes:

[0009] (1) After dehydrating and crushing the gasification fine slag, gasification fine slag powder is obtained;

[0010] (2) The gasification fine slag powder is contacted with oxygen for combustion to obtain flue gas and ash;

[0011] (3) Part of the flue gas is returned to (1) to carry the gasification fine slag powder into contact with the oxygen for combustion;

[0012] Before combustion, elemental analysis is performed on the gasification fine slag powder to determine the content and ratio of elements, and the results are input into the control system;

[0013] According to the element content and ratio of the gasification fine slag powder and the feeding amount, the control system outputs a signal and adjusts the amount of the flue gas, and controls the oxygen concentration during combustion to be 30 - 50 vol%, and the excess air coefficient to be 1.1 - 1.2.

[0014] A second aspect of the present invention provides a system for treating gasification fine slag, characterized in that the system includes a dryer 3, a silo 5, a boiler 8, a heat exchanger 11, a bag filter 12, a flue gas fan 18, an oxygen blower 19, and a control system 21;

[0015] The outlet of the dryer 3 is connected to the inlet of the silo 5 for dehydrating the gasification fine slag;

[0016] The outlet of the silo 5 is connected to the inlet of the boiler 8 for crushing the dehydrated gasification fine slag;

[0017] The outlet of the flue gas fan 18 is connected to the inlet of the silo 5 for pneumatically transporting the crushed gasification fine slag to the boiler 8;

[0018] The outlet of the boiler 8 is connected to the inlet of the bag filter 12 through the heat exchanger 11 for burning the gasification fine slag;

[0019] The outlet of the heat exchanger 11 is connected to the inlet of the boiler 8 for sending the heat-exchanged oxygen into the boiler for combustion;

[0020] The outlet of the oxygen blower 19 is connected to the inlet of the heat exchanger 11 for oxygen supply;

[0021] The control system 21 is connected to the oxygen blower 19 and the flue gas fan 18 for controlling the oxygen concentration and the excess air coefficient in the boiler 8.

[0022] The third aspect of the present invention provides an application of the method for treating gasification fine slag described in the first aspect and / or the system for treating gasification fine slag described in the second aspect in the treatment of gasification fine slag.

[0023] Through the above technical solutions, the method, system and application for treating gasification fine slag provided by the present invention achieve the following beneficial effects:

[0024] 1. According to the feeding amount of the gasification fine slag powder and the fuel element analysis, the control system controls the oxygen concentration to be 30 - 50 vol%, and controls the excess air coefficient inside the furnace to be 1.1 - 1.2, which can ensure that the gasification fine slag is in an oxygen-enriched atmosphere, strengthen and promote the ignition and burnout of the gasification fine slag, and ensure the stable and full combustion of the gasification fine slag;

[0025] 2. The high-concentration carbon dioxide flue gas after being dust-removed by the bag filter enters the condenser, and the carbon dioxide is separated through the gas-liquid separator, realizing carbon dioxide capture, reducing carbon dioxide emissions, and the carbon content of the ash slag is not more than 5 wt%, which is beneficial to subsequent resource utilization; at the same time, the water generated during the drying process of the gasification fine slag and the water after condensation and gas-liquid separation in the flue gas are sent to the storage pool to realize the recycling of water resources. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the system for treating gasification fine slag.

[0027] Description of the Reference Numerals

[0028] 1. Slurry pump; 2. Gasification fine slag conveying pipeline; 3. Dryer; 4. Dry water collection pipeline; 5. Silo; 6. Gasification fine slag conveying pipeline at the silo outlet; 7. Storage pool; 8. Boiler; 9. Slag collector; 10. Flue gas condensate collection pipeline; 11. Heat exchanger; 12. Bag filter; 13. Flue gas pipeline at the outlet of the bag filter; 14. Flue gas condenser; 15. Carbon dioxide storage tank; 16. Gas-liquid separator; 17. Induced draft fan recirculating flue gas inlet pipeline; 18. Recirculating flue gas fan; 19. Pure oxygen blower; 20. Oxygen supply pipeline; 21. Control system; 22. Silo air supply inlet pipeline. Detailed Embodiments

[0029] In the ranges disclosed herein, the endpoints and any value are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0030] The first aspect of the present invention provides a method for treating gasification fine slag, characterized in that the method includes:

[0031] (1) After dehydrating and crushing the gasification fine slag, gasification fine slag powder is obtained;

[0032] (2) The gasification fine slag powder is contacted with oxygen for combustion to obtain flue gas and ash;

[0033] (3) Part of the flue gas is returned to step (1) to carry the gasification fine slag powder into contact with the oxygen for combustion;

[0034] Among them, before combustion, elemental analysis is performed on the gasification fine slag powder to determine the content of each element and the ratio of the content of each element in the gasification fine slag powder;

[0035] According to the content of each element and the ratio of the content of each element in the gasification fine slag powder, the feeding amount of the gasification fine slag powder is controlled and the feeding amount of the flue gas returned to step (1) in step (3) is controlled, so that the oxygen concentration during combustion is 30-50 vol%, and the excess air coefficient is 1.1-1.2.

[0036] In the present invention, according to the feeding amount of the gasification fine slag and the analysis of elements (C, H, O, N, S), the oxygen concentration is controlled to be 30-50 vol% by the control system, and the excess air coefficient inside the furnace is controlled to be 1.1-1.2, which can ensure that the gasification fine slag is in an oxygen-enriched atmosphere, strengthen and promote the ignition and burnout of the gasification fine slag, ensure the stable and complete combustion of the gasification fine slag, make the carbon content of the obtained ash slag relatively low, and is beneficial to the efficient treatment and subsequent resource utilization of the gasification fine slag.

[0037] According to the present invention, the source of the gasification fine slag is not particularly limited. The gasification fine slag involved in the embodiments of the present invention is a high-water-content filter cake obtained by wet removal of coal chemical gasification fly ash.

[0038] In the present invention, the dry basis fixed carbon content of the high-water-content filter cake is greater than 20 wt%, the water content is 50-70 wt%, and the particle size is not greater than 500 μm.

[0039] According to the present invention, the water content of the gasification fine slag powder is 10-30 wt%.

[0040] According to the present invention, the particle size of the gasification fine slag powder is not greater than 100 μm.

[0041] According to the present invention, the temperature of the flue gas is 150-250 °C.

[0042] Further, the method further includes heat-exchanging the flue gas and the oxygen so that the temperature of the oxygen in step (2) is 200-300 °C

[0043] In the present invention, when the temperature during combustion after heat exchange satisfies the above range, it can promote the ignition and combustion of the gasification fine slag in the furnace.

[0044] According to the present invention, the flue gas is subjected to gas-liquid separation to obtain dry flue gas.

[0045] According to the present invention, in the dry flue gas, the carbon dioxide concentration is not less than 95 vol%.

[0046] A second aspect of the present invention provides a system for treating gasified fine slag, characterized in that the system includes a dryer 3, a silo 5, a boiler 8, a bag filter 12, a flue gas fan 18, an oxygen blower 19 and a control system 21;

[0047] The gasified fine slag is transported to the dryer 3 for dehydration;

[0048] The inlet of the silo 5 is communicated with the outlet of the dryer 3, and is used for crushing the dehydrated gasified fine slag to obtain gasified fine slag powder;

[0049] The inlet of the flue gas fan 18 is communicated with the outlet of the bag filter 12, and the outlet of the flue gas fan 18 is communicated with the inlet of the silo 5, and is used for recycling the flue gas generated during combustion for pneumatic conveying of the gasified fine slag powder in the silo 5;

[0050] The inlet of the boiler 8 is communicated with the silo 5, and is used for burning the gasified fine slag powder to obtain a gas-solid mixture containing flue gas and ash;

[0051] The inlet of the bag filter 12 is communicated with the outlet of the boiler 8, and is used for separating the gas-solid mixture to obtain flue gas and ash;

[0052] The oxygen blower 19 is communicated with the boiler 8, and is used for providing oxygen required for combustion;

[0053] The control system 21 is respectively communicated with the oxygen blower 19 and the flue gas fan 18, and is used for controlling the feeding amount of the gasified fine slag powder and controlling the flow rate of the flue gas returned from step 3 to step 1, so that the oxygen concentration during combustion is 30-50 vol%, and the excess air coefficient is 1.1-1.2.

[0054] According to the present invention, the system further includes: a slurry pump 1, a water storage tank 7, a slag collector 9, a heat exchanger 11, a flue gas condenser 14, a carbon dioxide gas storage tank 15 and a gas-liquid separator 16;

[0055] Among them, the outlet of the slurry pump 1 is communicated with the inlet of the dryer 3, and is used for transporting the gasified fine slag to the dryer 3 to dehydrate the gasified fine slag to a water content of 10-30 wt%;

[0056] The water storage tank 7 is communicated with the dryer 3, and is used for storing the water removed from the gasified fine slag;

[0057] The slag collector 9 is arranged at the bottom of the boiler 8 and is used for collecting the slag after combustion;

[0058] The heat exchanger 11 is communicated with the inlet of the boiler 8 and is used for sending the oxygen after heat exchange into the boiler 8;

[0059] The inlet of the flue gas condenser 14 is communicated with the outlet of the bag filter 12 and is used for condensing the flue gas;

[0060] The inlet of the gas-liquid separator 16 is communicated with the outlet of the flue gas condenser 14 and is used for separating the gas and liquid of the condensed flue gas;

[0061] The outlet of the gas-liquid separator 16 is communicated with the carbon dioxide storage tank 15, and the separated gas enters the carbon dioxide storage tank 15;

[0062] The gas-liquid separator 16 is communicated with the water storage tank 7, and the separated water enters the water storage tank 7.

[0063] In the present invention, the high-concentration carbon dioxide flue gas after being dust-removed by the bag filter enters the condenser, and carbon dioxide is separated out through the gas-liquid separator, realizing carbon dioxide capture and reducing carbon dioxide emissions; at the same time, the water generated during the gasification fine slag drying process and the water after condensation and gas-liquid separation in the flue gas are sent to the water storage tank to realize the recycling of water resources.

[0064] According to the present invention, the system further includes: a gasification fine slag powder conveying pipeline 2, a gasification fine slag conveying pipeline 6 at the outlet of the silo, a flue gas condensate collecting pipeline 10, a flue gas pipeline at the outlet of the bag filter 13, an induced draft fan flue gas inlet pipeline 17, and a silo air supply inlet pipeline 22, which are respectively used for connecting two different devices.

[0065] A specific embodiment in the present invention: as Figure 1 shown

[0066] The outlet of the slag slurry machine 1 is communicated with the inlet of the dryer 3 through the gasification fine slag powder conveying pipeline 2, and is used for conveying the gasification fine slag to the dryer 3 to dehydrate the gasification fine slag to a water content of 10-30 wt%;

[0067] The water storage tank 7 is communicated with the dryer 3 through the dry water collecting pipeline 4 and is used for storing the water removed from the gasification fine slag;

[0068] The inlet of the silo 5 is communicated with the outlet of the dryer 3 and is used for crushing the dehydrated gasification fine slag into gasification fine slag powder with a particle size not greater than 100 μm;

[0069] The inlet of the flue gas fan 18 is connected to the outlet of the bag filter 12 through the induced draft fan recirculating flue gas inlet pipe 17, and the outlet of the flue gas fan 18 is connected to the inlet of the silo 5 through the oxygen supply pipe 22, for circulating the flue gas generated during combustion for the pneumatic conveying of the gasified fine slag powder in the silo 5;

[0070] The inlet of the boiler 8 is connected to the silo 5 through the gasified fine slag conveying pipe 6 at the silo outlet, for burning the gasified fine slag powder to obtain a gas-solid mixture containing flue gas and ash;

[0071] The slag collector 9 is arranged at the bottom of the boiler 8, for collecting the slag after combustion;

[0072] The outlet of the oxygen blower 19 is connected to the inlet of the heat exchanger 11, for supplying oxygen;

[0073] The outlet of the heat exchanger 11 is connected to the inlet of the boiler 8, for sending the oxygen at 200 - 300 °C after heat exchange into the boiler for combustion

[0074] The inlet of the bag filter 12 is connected to the outlet of the heat exchanger 11, for separating the gas-solid mixture to obtain flue gas and ash;

[0075] The inlet of the flue gas condenser 14 is connected to the outlet of the bag filter 12 through the bag filter outlet flue gas pipe 13, for condensing the flue gas;

[0076] The inlet of the gas-liquid separator 16 is connected to the outlet of the flue gas condenser 14, for separating the condensed flue gas into gas and liquid;

[0077] The outlet of the gas-liquid separator 16 is connected to the carbon dioxide storage tank 15, and the separated gas enters the carbon dioxide storage tank 15;

[0078] The gas-liquid separator 16 is connected to the water storage tank 7 through the flue gas condensate collection pipe 10, and the separated water enters the water storage tank 7

[0079] The control system 21 is respectively connected to the oxygen blower 19 and the flue gas fan 18, for controlling the feeding amount of the gasified fine slag powder and the feeding amount of the flue gas returned to step 1 in step 3, so that the oxygen concentration during combustion is 30 - 50 vol%, and the excess air coefficient is 1.1 - 1.2.

[0080] The third aspect of the present invention provides an application of the method for treating gasified fine slag described in the first aspect and / or the system for treating gasified fine slag described in the second aspect in the treatment of gasified fine slag.

[0081] The present invention will be described in detail below through embodiments.

[0082] Vaporized fine slag, particle size: less than 500 μm;

[0083] Proximate analysis: Moisture content as received (M ar ) 69.7 wt%, ash content on dry basis (A d ) 47.3 wt%, volatile matter content on dry basis (V d ) 4.1 wt%, fixed carbon content on dry basis (FC d ) 48.6 wt%;

[0084] Ultimate analysis: Carbon content on dry basis (C d ) 50.19 wt%, hydrogen content on dry basis (H d ) 0.46 wt%, nitrogen content on dry basis (N d ) 0.42 wt%, sulfur content on dry basis (S d ) 1.52 wt%.

[0085] Example 1

[0086] As Figure 1 shown, the outlet of the slurry pump 1 is connected to the inlet of the dryer 3 through the vaporized fine slag powder conveying pipeline 2 for transporting the vaporized fine slag to the dryer 3 to dehydrate the vaporized fine slag to a moisture content of 20 wt%;

[0087] The water storage tank 7 is connected to the dryer 3 through the dried water collection pipeline 4 for storing the water removed from the vaporized fine slag;

[0088] The inlet of the storage bin 5 is connected to the outlet of the dryer 3 for crushing the dehydrated vaporized fine slag into vaporized fine slag powder with a particle size of 100 μm or less;

[0089] The inlet of the flue gas fan 18 is connected to the outlet of the bag filter 12 through the induced draft fan recirculating flue gas inlet pipeline 17, and the outlet of the flue gas fan 18 is connected to the inlet of the storage bin 5 through the oxygen supply pipeline 22 for recycling the flue gas generated during combustion for pneumatic conveying of the vaporized fine slag powder in the storage bin 5;

[0090] The inlet of the boiler 8 is connected to the storage bin 5 through the vaporized fine slag conveying pipeline 6 at the outlet of the storage bin for burning the vaporized fine slag powder to obtain a gas-solid mixture containing flue gas and ash;

[0091] The slag collector 9 is arranged at the bottom of the boiler 8 for collecting the slag after combustion;

[0092] The outlet of the oxygen blower 19 is connected to the inlet of the heat exchanger 11 for supplying oxygen;

[0093] The outlet of the heat exchanger 11 is connected to the inlet of the boiler 8, and is used to send the oxygen at 300°C after heat exchange into the boiler for combustion.

[0094] The inlet of the bag filter 12 is connected to the outlet of the heat exchanger 11, and is used to separate the gas-solid mixture to obtain flue gas and ash.

[0095] The inlet of the flue gas condenser 14 is connected to the outlet of the bag filter through the flue gas pipeline 13 at the outlet of the bag filter and the outlet of the bag filter 12, and is used to condense the flue gas.

[0096] The inlet of the gas-liquid separator 16 is connected to the outlet of the flue gas condenser 14, and is used to separate the condensed flue gas into gas and liquid to obtain dry flue gas.

[0097] The outlet of the gas-liquid separator 16 is connected to the carbon dioxide storage tank 15, and the above-mentioned dry flue gas is transported to the carbon dioxide storage tank 15 for storage.

[0098] The gas-liquid separator 16 is connected to the storage tank 7 through the flue gas condensate collection pipeline 10, and the separated water enters the storage tank 7.

[0099] The control system 21 is respectively connected to the oxygen blower 19 and the flue gas blower 18, and is used to control the feeding amount of the gasified fine slag powder and the feeding amount of the flue gas returned to step 1 in step 3, so that the oxygen concentration during combustion is 50 vol%, and the excess air coefficient is 1.2.

[0100] Finally, the carbon dioxide concentration in the dry flue gas is 95 vol%, and the system can effectively treat the gasified fine slag, and the carbon content of the obtained ash slag is 3.5 wt%, which can be used for subsequent resource utilization.

[0101] Example 2

[0102] It is the same as the method of Example 1, except that the oxygen concentration during combustion is controlled to be 40 vol%.

[0103] Finally, the carbon dioxide concentration in the dry flue gas is 95 vol%, and the carbon content of the obtained ash slag is 4 wt%.

[0104] Example 3

[0105] It is the same as the method of Example 1, except that the excess air coefficient during combustion is controlled to be 1.1.

[0106] Finally, the carbon dioxide concentration in the dry flue gas is 96 vol%, and the carbon content of the obtained ash slag is 4.5 wt%.

[0107] Comparative Example 1

[0108] Consistent with the method of Example 1, except that the oxygen concentration during combustion is controlled to be 20 vol%.

[0109] The carbon dioxide concentration in the dry flue gas is 94 vol%, and the carbon content of the obtained ash residue is 8 wt%, and even the stable treatment of the gasified fine slag cannot be achieved.

[0110] Comparative Example 2

[0111] Consistent with the method of Example 1, except that the excess air coefficient during combustion is controlled to be 1.

[0112] The carbon dioxide concentration in the dry flue gas is 93 vol%, and the carbon content of the obtained ash residue is 8 wt%, and even the stable treatment of the gasified fine slag cannot be achieved.

[0113] From the results of Examples 1-4, it can be seen that by using the method and system for treating gasified fine slag provided by the present invention, good technical effects can be obtained, the carbon dioxide concentration is above 95 vol%, and the carbon content of the obtained ash residue is not more than 5 wt%. This system can effectively treat the gasified fine slag, and carbon dioxide and water are collected and utilized, reducing carbon dioxide emissions and saving water resources.

[0114] For Comparative Examples 1-2 that do not meet the technical solution of the present invention, the carbon dioxide concentration is below 95 vol%, and the carbon content of the obtained ash residue is relatively high, which is not conducive to subsequent resource utilization, and even the stable treatment of the gasified fine slag cannot be achieved.

[0115] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for treating gasification fine slag, characterized in that, the method comprises: (1) dehydrating and crushing the gasification fine slag to obtain gasification fine slag powder; (2) contacting the gasification fine slag powder with oxygen for combustion to obtain flue gas and ash; (3) returning part of the flue gas to step (1) for carrying the gasification fine slag powder to contact with the oxygen for combustion; wherein, before combustion, elemental analysis is performed on the gasification fine slag powder to determine the content of each element and the ratio of the content of each element in the gasification fine slag powder; According to the content of each element and the ratio of the content of each element in the gasification fine slag powder, the feeding amount of the gasification fine slag powder is controlled and the feeding amount of the flue gas returned to step (1) in step (3) is controlled, so that the oxygen concentration during combustion is 40-50 vol%, and the excess air coefficient is 1.1-1.2; The flue gas and the oxygen are heat-exchanged so that the temperature of the oxygen in step (2) is 200-300 °C; The method further comprises: performing gas-liquid separation on the flue gas to obtain dry flue gas; The carbon dioxide concentration in the dry flue gas is not less than 95 vol%.

2. The method according to claim 1, wherein, the water content of the gasification fine slag powder is 10-30 wt%.

3. The method according to claim 2, wherein, the water content of the gasification fine slag powder is 10-20 wt%.

4. The method according to any one of claims 1-3, wherein, the particle size of the gasification fine slag powder is not greater than 100 μm.

5. The method according to claim 4, wherein, the temperature of the flue gas is 150-250 °C.

6. An apparatus for implementing the method for treating gasification fine slag according to claim 1, characterized in that, the apparatus comprises a dryer (3), a silo (5), a boiler (8), a bag filter (12), a flue gas fan (18), an oxygen blower (19) and a control system (21); The gasification fine slag is transported to the dryer (3) for dehydration; The inlet of the silo (5) is communicated with the outlet of the dryer (3) for crushing the dehydrated gasification fine slag to obtain gasification fine slag powder; The inlet of the flue gas fan (18) is communicated with the outlet of the bag filter (12), and the outlet of the flue gas fan (18) is communicated with the inlet of the silo (5) for circulating the flue gas generated during combustion for pneumatic conveying of the gasification fine slag powder in the silo (5); The inlet of the boiler (8) is communicated with the silo (5) for burning the gasification fine slag powder to obtain a gas-solid mixture containing flue gas and ash; The inlet of the bag filter (12) is communicated with the outlet of the boiler (8) for separating the gas-solid mixture to obtain flue gas and ash; The oxygen blower (19) is communicated with the boiler (8) for providing the oxygen required for combustion; The control system (21) is respectively connected to the oxygen blower (19) and the flue gas blower (18), and is used to control the feeding amount of the gasified fine slag powder and the feeding amount of the flue gas returned to step (1) in step (3), so that the oxygen concentration during combustion is 40-50 vol%, and the excess air coefficient is 1.1-1.2; The device further includes: a slurry pump (1), a water storage tank (7), a slag collector (9), a heat exchanger (11), a flue gas condenser (14), a carbon dioxide gas storage tank (15), and a gas-liquid separator (16); Among them, the slurry pump (1) is connected to the inlet of the dryer (3) and is used to transport the gasified fine slag into the dryer (3); The water storage tank (7) is connected to the dryer (3) and is used to store the water removed from the gasified fine slag; The slag collector (9) is arranged at the bottom of the boiler (8) and is used to collect the slag after combustion; The heat exchanger (11) is connected to the inlet of the boiler (8) and is used to send the heat-exchanged oxygen into the boiler (8); The inlet of the flue gas condenser (14) is connected to the outlet of the bag filter (12) and is used to condense the flue gas; The inlet of the gas-liquid separator (16) is connected to the outlet of the flue gas condenser (14) and is used to separate the gas and liquid of the condensed flue gas; The outlet of the gas-liquid separator (16) is connected to the carbon dioxide gas storage tank (15), and the separated gas enters the carbon dioxide gas storage tank (15); The gas-liquid separator (16) is connected to the water storage tank (7), and the separated water enters the water storage tank (7).

7. The device according to claim 6, wherein, The device further includes: a gasified fine slag conveying pipeline (2), a gasified fine slag conveying pipeline at the bin outlet (6), a flue gas condensate collection pipeline (10), a flue gas pipeline at the outlet of the bag filter (13), a recirculating flue gas inlet pipeline of the induced draft fan (17), and a bin air supply inlet pipeline (22), which are respectively used to connect two different devices.

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