Coal-based semi-closed composite working medium cycle system under high temperature and high pressure

Abstract

The application provides a coal-based semi-closed composite working medium cycle system under high temperature and high pressure. The system comprises a dryer, a coal mill, a gasification furnace, a heat exchanger, a reactor, a compressor, a combustion chamber, a turbine unit, a regenerator and a condenser. The dryer is used for receiving raw coal with an inlet temperature and pressure of 15 DEG C and 0.1 MPa, and the raw coal is dried to 2% moisture content by using N2 with a temperature and pressure of 174.23 DEG C and 0.103 MPa, and then the raw coal is sent to the coal mill. The turbine unit receives the combustion flue gas with a temperature and pressure of 1450 DEG C and 38 MPa output by the combustion chamber, the combustion flue gas enters the sCO2 turbine to expand and do work, and the flue gas with a temperature and pressure of 792.46 DEG C and 1.4 MPa is output to the regenerator. The circulating CO2 output by the condenser is mixed with the compressed oxygen used for combustion to form an oxidant flow, and then the oxidant flow is compressed to 38 MPa by the compressor and sent to the reheater to complete the preheating process. The application proposes to improve the turbine inlet temperature and pressure, increase the heat efficiency and specific work of unit mass working medium, and improve the system efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of coal-based semi-closed composite working fluid circulation systems, and more particularly to a coal-based semi-closed composite working fluid circulation system with a turbine inlet working fluid temperature of 1450℃ and a pressure of 38MPa. Background Technology

[0002] The coal-based semi-closed composite working fluid circulation system can recover the generated CO2 by using pure oxygen combustion technology after coal is converted into syngas, achieving zero carbon emissions. At the same time, due to the high thermodynamic parameters of the working fluid at the turbine inlet, it is more efficient than the integrated coal gasification combined cycle system (IGCC) using the same gasifier, demonstrating superior thermodynamic performance.

[0003] As the temperature and pressure of the working fluid at the turbine inlet of the coal-based semi-closed composite working fluid circulation system increase, the required coolant mass flow rate for the turbine blades increases, reducing the system's thermal efficiency. Simultaneously, since the heat released from syngas combustion remains constant, the decrease in the circulating CO2 mass flow rate when the turbine inlet temperature and pressure rises leads to a decrease in the main gas flow rate, further reducing the system's thermal efficiency. However, increasing the turbine inlet temperature and pressure of the working fluid in the coal-based semi-closed composite working fluid circulation system increases the thermal efficiency and specific work per unit mass of working fluid, significantly improving the system's thermal efficiency. Summary of the Invention

[0004] The embodiments of the present invention provide a coal-based semi-closed composite working fluid circulation system under high temperature and high pressure, so as to effectively improve the working efficiency of the coal-based semi-closed composite working fluid circulation system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A coal-based semi-closed composite working fluid circulation system under high temperature and high pressure includes: a dryer, a coal mill, a gasifier, a heat exchanger, a dust collector, a reactor, a desulfurization furnace, a compressor, a combustion chamber, a turbine unit, a regenerator, and a condenser;

[0007] The dryer is used to receive raw coal with an inlet temperature and pressure of 15℃ and 0.1MPa, and to dry the raw coal to a moisture content of 2% using N2 with a temperature and pressure of 174.23℃ and 0.103MPa, respectively, before feeding it into the coal mill.

[0008] The aforementioned coal mill is used to grind raw coal into pulverized coal, and the energy consumption of the coal mill is 15 kWh per ton of coal. The pulverized coal is transported to the gasifier by CO2 at a temperature and pressure of 53.67°C and 4 MPa, separated from the sCO2 power cycle;

[0009] The gasifier is used to receive pulverized coal, steam and O2. The temperature and pressure of the steam are 300℃ and 4MPa, respectively, and the temperature and pressure of the O2 are 191.29℃ and 4MPa, respectively. The pulverized coal, steam and O2 react to generate syngas.

[0010] The heat exchanger, through which the syngas leaving the gasifier is mixed with the reflux syngas to obtain syngas at 1100°C, is cooled to 350°C in three heat exchangers. The syngas at 1100°C and 4 MPa, after passing through the first heat exchanger, has its temperature and pressure reduced to 736°C and 3.96 MPa, releasing heat used to heat the CO2 used to regulate the combustion chamber temperature. The syngas at 736°C and 3.96 MPa, after passing through the second heat exchanger, has its temperature and pressure reduced to 472.74°C and 3.92 MPa, releasing heat used to heat the syngas entering the combustion chamber. The syngas at 472.74°C and 3.92 MPa, after passing through the third heat exchanger, has its temperature reduced to 350°C and 3.88 MPa, releasing heat used to heat the N2 used for drying pulverized coal.

[0011] The dust collector is used to receive syngas output from the heat exchanger at a temperature of 350°C and a pressure of 3.88 MPa, and to remove ash particles from the syngas.

[0012] The desulfurization furnace is used to receive syngas at a temperature and pressure of 38°C and 3.72MPa, remove H2S from the syngas, and the desulfurized syngas enters the compressor.

[0013] The compressor is used to compress the received desulfurized syngas and output syngas with a temperature of 365°C and a pressure of 38.77 MPa.

[0014] The preheater is used to preheat the syngas output from the compressor. The syngas output from the preheater, with a temperature of 726°C and a pressure of 38.38 MPa, is then sent into the combustion chamber of the sCO2 power cycle.

[0015] The combustion chamber is used to receive O2 diluted with CO2 at a temperature and pressure of 723.34℃ and 38.38MPa, recovered CO2 at a temperature and pressure of 859.41℃ and 38.38MPa to regulate the combustion chamber temperature, and syngas output from the preheater at a temperature and pressure of 726℃ and 38.38MPa. The combustion chamber outputs combustion flue gas composed of CO2 and H2O at a temperature and pressure of 1450℃ and 38MPa.

[0016] The turbine unit is used to receive combustion flue gas with a temperature of 1450°C and a pressure of 38MPa output from the combustion chamber. The combustion flue gas enters the sCO2 turbine to expand and do work. The turbine unit outputs flue gas with a temperature of 792.46°C and a pressure of 1.4MPa to the regenerator.

[0017] The regenerator is used to receive flue gas output from the turbine unit at a temperature of 792.46℃ and a pressure of 1.4MPa. After the regenerator uses the heat from the flue gas to heat the recovered sCO2, diluted O2, and CO2 used to cool the turbine, the temperature and pressure of the flue gas drop to 69.8℃ and 1.372MPa, respectively. The flue gas output from the regenerator is then transferred to the condenser.

[0018] The condenser is used to cool the flue gas output from the regenerator using cooling water. Water in the flue gas is removed by the condenser, and the flue gas is cooled to 25°C.

[0019] The CO2 output from the condenser is divided into three streams: one stream of CO2 is produced by the combustion of CO in the syngas generated by coal gasification and is used for carbon capture; the second stream of CO2 is used for coal transportation; and the third stream of CO2 is used as recovered CO2 and as a working fluid to complete the power cycle. The recovered CO2 is first compressed to 8MPa in the compressor, then pressurized to 12MPa in the CO2 pump, and then cooled to ambient temperature.

[0020] The recovered CO2 at 12 MPa is split into two streams: the first stream of CO2 mixes with compressed oxygen for combustion to form an oxidant stream, which is then compressed to 39.17 MPa in the compressor and sent to the reheater to complete the preheating process; the other stream of CO2 is pressurized to 39.56 MPa in the CO2 pump and further split into two streams in the reheater for preheating. One high-pressure CO2 stream is used to regulate the temperature of the combustion chamber, and the other high-pressure CO2 stream is used as a coolant for the sCO2 turbine.

[0021] Preferably, the syngas leaving the dust collector is split into two streams: one stream is mixed with the original syngas, and the second stream is sent to a heat exchanger to heat steam for coal gasification; after heating the steam, the temperature and pressure of the syngas drop to 211.7°C and 3.8 MPa, respectively. Then, COS in the syngas is hydrolyzed under the action of a catalyst and converted into H2S that can be removed by a desulfurization furnace; then, the temperature and pressure of the syngas drop to 38°C and 3.72 MPa after releasing heat in a regenerator, and the released heat is used to heat N2.

[0022] Preferably, the gasifier operates at a temperature of 1350°C and a pressure of 4 MPa.

[0023] Preferably, the turbine unit is a 4-stage turbine, including 4 stages of blades, wherein the first 3 stages of blades need to be cooled, and the 4th stage of blades does not need to be cooled.

[0024] As can be seen from the technical solutions provided by the embodiments of the present invention above, the present invention proposes to significantly increase the thermal efficiency and specific work of the working fluid per unit mass by increasing the turbine inlet temperature and pressure. This can not only compensate for the negative impact of the increase in the mass flow rate of the coolant and the decrease in the mass flow rate of the main gas flow on the system efficiency, but also further improve the system efficiency.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a coal-based semi-closed composite working fluid circulation system with a turbine inlet working fluid temperature and pressure of 1450℃ and 38MPa, provided for an embodiment of the present invention.

[0028] In the figure: N2-1, N2-2, N2-3, N2-4, N2-ST are nitrogen streams with different thermodynamic parameters; O2-1, O2-2(3), O2-4 are oxygen streams with different thermodynamic parameters; SG-1, SG-2, SG-3, SG-4, SG-5, SG-6, SG-7, SG-8, SG-9, SG-10, SG-11, SG-RE are synthesis streams with different thermodynamic parameters; FG-1, FG-2, FG-3, FG-4 are combustion chamber exhaust streams with different thermodynamic parameters; CO2-1, CO2-2, CO2-3, CO2-4, CO2-5, CO2-6, CO2-7, CO2-8, CO2-9, CO2-10 are carbon dioxide streams with different thermodynamic parameters; CO2 / O2-1, CO2 / O2-2, CO2 / O2-3 are mixed streams of carbon dioxide and oxygen. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0031] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0032] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments. These embodiments do not constitute a limitation on the embodiments of the present invention.

[0033] This invention is based on a coal-based semi-closed composite working fluid circulation system with conventional turbine inlet temperature and pressure of 1150℃ and 30MPa. By studying the change in system output power when turbine inlet temperature and pressure increase, the influence of the specific work per unit mass of working fluid, the increase in coolant mass flow rate, and the decrease in main gas flow rate on system efficiency is quantified. A coal-based semi-closed composite working fluid circulation system with higher turbine inlet temperature and pressure is proposed.

[0034] The structure of a coal-based semi-closed composite working fluid circulation system with a turbine inlet working fluid temperature of 1450℃ and a pressure of 38MPa, as proposed in this embodiment of the invention, is as follows: Figure 1 As shown. It includes: dryer, coal mill, gasifier, heat exchanger, dust collector, reactor, desulfurization furnace, compressor, combustion chamber, turbine unit, regenerator and condenser.

[0035] The dryer is used to receive raw coal with an inlet temperature and pressure of 15℃ and 0.1MPa, and uses N2 with a temperature and pressure of 174.23℃ and 0.103MPa to dry the raw coal to a moisture content of 2% before it enters the coal mill.

[0036] A coal mill is used to grind raw coal into pulverized coal. The energy consumption of the coal mill is 15 kWh per ton of coal. The pulverized coal is fed to the gasifier by CO2 at a temperature and pressure of 53.67°C and 4 MPa, which is separated from the sCO2 power cycle.

[0037] The gasifier receives pulverized coal, steam, and oxygen (O2). The steam temperature and pressure are 300℃ and 4MPa, respectively, and the O2 temperature and pressure are 191.29℃ and 4MPa, respectively. The pulverized coal, steam, and O2 react to produce syngas. The gasifier's operating parameters are 1350℃ and 4MPa.

[0038] In the heat exchanger, the syngas leaving the gasifier is mixed with the reflux syngas and cooled to 1100°C. The syngas is then cooled to 350°C in three heat exchangers. After passing through the first heat exchanger at 1100°C and 4 MPa, the syngas's temperature and pressure decrease to 736°C and 3.96 MPa, and the released heat is used to heat the sCO2 used to regulate the combustion chamber temperature. After passing through the second heat exchanger at 736°C and 3.96 MPa, the syngas's temperature and pressure decrease to 472.74°C and 3.92 MPa, and the released heat is used to heat the syngas entering the combustion chamber. After passing through the third heat exchanger at 472.74°C and 3.92 MPa, the temperature decreases to 350°C and 3.88 MPa, and the released heat is used to heat the N2 used for drying the pulverized coal.

[0039] The dust collector is used to receive syngas output from the heat exchanger at a temperature and pressure of 350℃ and 3.88MPa, and to remove ash particles from the syngas.

[0040] The syngas leaving the dust collector is split into two streams. One stream is mixed with the original syngas, and the second stream is sent to a heat exchanger to heat steam for coal gasification. After heating the steam, the temperature and pressure of the syngas drop to 211.7°C and 3.8 MPa, respectively. Then, COS in the syngas is hydrolyzed by a catalyst and converted into H2S, which can be removed by the desulfurization furnace. The syngas then releases heat in a regenerator, reducing its temperature and pressure to 38°C and 3.72 MPa. The released heat is used to heat N2.

[0041] The desulfurization furnace receives syngas at 38℃ and 3.72MPa, removing H2S from it. The desulfurized syngas then enters the compressor.

[0042] The compressor is used to compress the received desulfurized syngas, and outputs syngas with a temperature of 365℃ and a pressure of 38.77MPa.

[0043] The preheater is used to preheat the syngas output from the compressor. The syngas output from the preheater, with a temperature of 726℃ and a pressure of 38.38MPa, is then sent into the combustion chamber of the sCO2 power cycle.

[0044] The combustion chamber receives O2 diluted with CO2 at a temperature of 723.34℃ and a pressure of 38.38 MPa, recovered CO2 at a temperature of 859.41℃ and a pressure of 38.38 MPa to regulate the combustion chamber temperature, and syngas from the preheater at a temperature of 726℃ and a pressure of 38.38 MPa. By reducing the mass flow rate of the recovered CO2, the outlet flue gas temperature of the combustion chamber is increased from 1150℃ to 1450℃, and the outlet pressure of the combustion chamber is 38 MPa. The combustion chamber outputs combustion flue gas mainly composed of CO2 and H2O at a temperature of 1450℃ and a pressure of 38 MPa.

[0045] The turbine unit converts the energy contained in the fluid working medium into mechanical work. The turbine unit receives combustion flue gas from the combustion chamber at a temperature of 1450℃ and a pressure of 38MPa. The combustion flue gas enters the sCO2 turbine for expansion and work. To prevent the turbine outlet temperature from exceeding the heat-bearing capacity of the regenerator materials, the turbine outlet pressure is reduced to 1.4MPa, and the turbine exhaust temperature is 792.46℃. The turbine is a four-stage turbine, including four stages of blades. The first three stages of blades require cooling, while the fourth stage does not. The turbine unit outputs flue gas at a temperature of 792.46℃ and a pressure of 1.4MPa to the regenerator.

[0046] To prevent the turbine unit's outlet temperature from exceeding the regenerator's material heat-bearing capacity, the turbine unit's outlet pressure is reduced to 1.4 MPa, and the exhaust gas from the turbine unit enters the regenerator to release heat. Due to the increased inlet temperature and pressure of the turbine unit, the circulating CO2 mass flow rate decreases, leading to a decrease in the main gas flow rate. Simultaneously, the coolant mass flow rate required by the turbine unit increases, causing a decrease in system thermal efficiency. However, the increased inlet temperature and pressure of the turbine unit significantly increases the specific work per unit mass of the working fluid. This not only compensates for the negative impact of the increased coolant mass flow rate and decreased main gas flow rate on system efficiency but also further improves system efficiency.

[0047] The regenerator is used to receive flue gas output from the turbine unit at a temperature of 792.46℃ and a pressure of 1.4MPa. After the regenerator uses the flue gas to heat the recovered sCO2, diluted O2 and CO2 used to cool the turbine, the temperature and pressure of the flue gas drop to 69.8℃ and 1.372MPa, respectively. The flue gas output from the regenerator is then transferred to the condenser.

[0048] Condenser: Used to cool the flue gas output from the regenerator using cooling water. Water in the flue gas is removed by the condenser, and the flue gas is cooled to 25°C.

[0049] The high-purity CO2 output from the condenser is split into three streams. One stream of CO2 is produced by the combustion of CO in the syngas generated from coal gasification and is used for carbon capture. The second stream of CO2 is used for coal transportation. The third stream of CO2, as recovered CO2, serves as the working fluid to complete the power cycle. The recovered CO2 is first compressed to 8 MPa in the compressor, then pressurized to 12 MPa in the CO2 pump, and then cooled to ambient temperature. The 12 MPa recovered CO2 is split into two streams. The first stream mixes with compressed oxygen for combustion to form an oxidant stream, which is then compressed to 39.17 MPa in the compressor and sent to the reheater for preheating. The other stream is pressurized to 39.56 MPa in the CO2 pump and further split into two streams in the reheater for preheating. One high-pressure CO2 stream is used to regulate the temperature of the combustion chamber, and the other high-pressure CO2 stream is used as a coolant for the sCO2 turbine.

[0050] The effects of the present invention will be explained below with reference to numerical examples.

[0051] A coal-based semi-closed composite working fluid circulation system with turbine inlet temperature and pressure of 1150℃ and 30MPa is used as the baseline system. This system is based on the same assumptions and parameter values ​​as a coal-based semi-closed composite working fluid circulation system with turbine inlet working fluid temperature and pressure of 1450℃ and 38MPa. The system assumptions and selected parameters are shown in Table 1 below:

[0052]

[0053] The system results are shown in Table 2:

[0054]

[0055]

[0056] As shown in Table 2, the thermal efficiency of the coal-based semi-closed composite working fluid circulation system is 41.42% when the turbine inlet working fluid temperature and pressure are 1150℃ and 30MPa. When the turbine inlet working fluid temperature and pressure are 1450℃ and 38MPa, the required coolant flow rate increases to 155.26 kg / s, and the main gas flow rate decreases to 1476.78 kg / s, thus reducing the system's thermal efficiency. However, the significant increase in the specific work per unit mass of the working fluid to 438.05 kW not only compensates for the negative impact of the increased coolant flow rate and decreased main gas flow rate on system efficiency but also further improves the system efficiency. The thermal efficiency of the coal-based semi-closed composite working fluid circulation system at turbine inlet working fluid temperature and pressure of 1450℃ and 38MPa is 44.27%, which is 2.85% higher than the baseline system, demonstrating that the present invention has achieved the expected beneficial effects.

[0057] In summary, by increasing the temperature and pressure of the working fluid at the turbine inlet to 1450°C and 38 MPa, the embodiments of the present invention significantly increase the thermal efficiency and specific work per unit mass of the working fluid. This not only compensates for the negative impact of increased coolant mass flow rate and decreased main gas flow rate on system efficiency, but also further improves system efficiency.

[0058] This invention proposes increasing the overall system thermal efficiency by raising the turbine inlet temperature and pressure. Since the heat released from syngas combustion remains constant, increasing the turbine inlet temperature and pressure leads to a decrease in the system's circulating CO2 mass flow rate, resulting in a decrease in the main gas flow rate. Simultaneously, the required coolant mass flow rate increases, causing a decrease in system thermal efficiency. However, the thermal efficiency and specific work per unit working fluid increase at higher temperatures and pressures. This not only compensates for the negative impact of increased coolant mass flow rate and decreased main gas flow rate on system efficiency but also further improves system efficiency. The system thermal efficiency of the coal-based semi-closed composite working fluid circulation system at a turbine inlet working fluid temperature and pressure of 1450℃ and 38MPa is 44.27%, compared to 2.85% in the system at 1150℃ and 30MPa. This achieves higher thermal efficiency without emitting CO2 to the outside environment.

[0059] This invention proposes to significantly increase the thermal efficiency and specific work per unit mass of working fluid by increasing the turbine inlet temperature and pressure. This can not only compensate for the negative impact of increased coolant mass flow rate and decreased main gas flow rate on system efficiency, but also further improve system efficiency.

[0060] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing the present invention.

[0061] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for apparatus or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The apparatus and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0062] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A coal-based semi-closed composite working fluid cycle system under high temperature and high pressure, characterized in that, The utility model relates to a kind of sCO2 power cycle, including: Dryer, coal mill, gasifier, heat exchanger, dust collector, reactor, sulfur removal furnace, compressor, preheater, combustion chamber, turbine unit, regenerator and condenser; The dryer is used to receive raw coal with inlet temperature and pressure of 15°C and 0.1MPa, and dry the raw coal to 2% moisture content using N2 with temperature and pressure of 174.23°C and 0.103MPa respectively, and then send the dried raw coal to the coal mill; The coal mill is used to grind the raw coal into coal powder, and the energy consumption of the coal mill is 15 kWh per ton of coal, and the coal powder is transported to the gasifier by CO2 separated from the sCO2 power cycle with temperature and pressure of 53.67°C and 4MPa respectively; The gasifier is used to receive coal powder, steam and O2, and the steam has temperature and pressure of 300°C and 4MPa respectively, and the O2 has temperature and pressure of 191.29°C and 4MPa respectively, and the coal powder, steam and O2 react to generate synthesis gas; The heat exchanger is used to mix the synthesis gas leaving the gasifier with the backflow synthesis gas to obtain synthesis gas with temperature of 1100°C, and the synthesis gas is cooled to 350°C in three heat exchangers, and after the synthesis gas with temperature and pressure of 1100°C and 4MPa respectively passes through the first heat exchanger, the temperature and pressure decrease to 736°C and 3.96MPa respectively, and the released heat is used to heat the CO2 for adjusting the temperature of the combustion chamber, and after the synthesis gas with temperature and pressure of 736°C and 3.96MPa respectively passes through the second heat exchanger, the temperature and pressure decrease to 472.74°C and 3.92MPa respectively, and the released heat is used to heat the synthesis gas entering the combustion chamber, and after the synthesis gas with temperature and pressure of 472.74°C and 3.92MPa respectively passes through the third heat exchanger, the temperature decreases to 350°C and 3.88MPa, and the released heat is used to heat the N2 for drying the coal powder; The dust collector is used to receive the synthesis gas with temperature and pressure of 350°C and 3.88MPa respectively output by the heat exchanger, and remove ash particles from the synthesis gas; The sulfur removal furnace is used to receive the synthesis gas with temperature and pressure of 38°C and 3.72MPa respectively, and remove H2S from the synthesis gas, and the desulfurized synthesis gas enters the compressor; The compressor is used to compress the received desulfurized synthesis gas, and output synthesis gas with temperature and pressure of 365°C and 38.77MPa respectively; The preheater is used to preheat the synthesis gas output by the compressor, and the preheater outputs synthesis gas with temperature and pressure of 726°C and 38.38MPa respectively, which is sent to the combustion chamber of the sCO2 power cycle; The combustion chamber is used to receive O2 diluted by CO2 with temperature and pressure of 723.34°C and 38.38MPa respectively, recovered CO2 with temperature and pressure of 859.41°C and 38.38MPa respectively for adjusting the temperature of the combustion chamber, and synthesis gas with temperature and pressure of 726°C and 38.38MPa respectively output by the preheater, and the combustion chamber outputs combustion flue gas composed of CO2 and H2O with temperature and pressure of 1450°C and 38MPa respectively. The turbine unit is used for receiving the combustion flue gas with a temperature of 1450 DEG C and a pressure of 38 MPa output by the combustion chamber, and the combustion flue gas enters the sCO2 turbine to expand and do work, and the turbine unit outputs the flue gas with a temperature of 792.46 DEG C and a pressure of 1.4 MPa to the regenerator; The regenerator is used for receiving the flue gas with a temperature of 792.46 DEG C and a pressure of 1.4 MPa output by the turbine unit, and the regenerator heats the recovered CO2, the diluted O2 and the CO2 for cooling the turbine by using the heat of the flue gas, and after the heating, the temperature and the pressure of the flue gas are reduced to 69.8 DEG C and 1.372 MPa, and the flue gas output by the regenerator is transmitted to the condenser; The condenser is used for cooling the flue gas output by the regenerator by using cooling water, and the water in the flue gas is removed by the condenser, and the flue gas is cooled to 25 DEG C; The CO2 output by the condenser is divided into three parts: one part of the CO2 is produced by burning the CO in the syngas generated by coal gasification and is used for carbon capture; the second part of the CO2 is used for coal transportation; and the third part of the CO2 is recovered as the working medium to complete the power cycle; the recovered CO2 is first compressed to 8 MPa in the compressor, and then pressurized to 12 MPa in the CO2 pump, and then cooled to the ambient temperature; The recovered CO2 with a pressure of 12 MPa is divided into two parts: one part of the CO2 is mixed with the compressed oxygen for combustion to form an oxidant flow, and then enters the air compressor to be compressed to 39.17 MPa, and then is sent into the reheater to complete the preheating process; the other part of the CO2 is pressurized to 39.56 MPa in the CO2 pump, and is further divided into two parts in the reheater to complete the preheating process, one part of the high-pressure CO2 is used for adjusting the temperature of the combustion chamber, and the other part of the high-pressure CO2 is used as the coolant of the sCO2 turbine.

2. The system of claim 1, wherein, The syngas leaving the dust remover is divided into two parts: one part is mixed with the original syngas, and the second part is sent into the heat exchanger to heat the steam for coal gasification; after the heating of the steam, the temperature and the pressure of the syngas are reduced to 211.7 DEG C and 3.8 MPa, and then the COS in the syngas is hydrolyzed into H2S which can be removed by the sulfur removal furnace under the action of the catalyst; then the syngas releases heat in the regenerator, and the temperature and the pressure of the syngas are reduced to 38 DEG C and 3.72 MPa, and the released heat is used to heat the N2.

3. The system of claim 1, wherein, The gasification furnace operates at a temperature of 1350 DEG C and a pressure of 4 MPa.

4. The system of claim 1, wherein, The turbine unit selects a 4-stage turbine including 4-stage blades, wherein the first 3-stage blades need to be cooled, and the 4th-stage blade does not need to be cooled.

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