Coal-based semi-closed power generation circulation system and operation method thereof

Abstract

The invention belongs to the technical field of coal-based semi-closed circulating power generation, and discloses a coal-based semi-closed power generation circulating system and an operation method thereof. A smoke outlet of the combustor is connected with an inlet of the gas turbine, an outlet of the gas turbine is connected with a hot side inlet of the heat regenerator, and a hot side outlet of the heat regenerator is connected with an inlet of the gas-liquid separator. A gas phase outlet of the gas-liquid separator is connected with an inlet of the precooler, and an outlet of the precooler is connected with an inlet of the compressor; an outlet of the compressor is connected with a cold side inlet of the heat regenerator, and a cold side outlet of the heat regenerator is connected with a circulating working medium inlet of the combustor. The outlet of the compressor is further connected with the inlet of the load rapid adjusting subsystem, and the outlet of the load rapid adjusting subsystem is connected with the inlet of the gas-liquid separator; the load rapid adjusting subsystem is used for storing the carbon dioxide working medium conveyed by the compressor or conveying the carbon dioxide working medium to the gas-liquid separator; according to the invention, rapid variable-load operation of the system is realized, and the peak regulation efficiency of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal-based semi-closed cycle power generation, and particularly relates to a coal-based semi-closed power generation cycle system and an operation method thereof. Background Art

[0002] With the rapid development of new energy power generation technologies such as wind power and photovoltaic power, with the advantages of almost zero emissions and rich resources, it is of great significance for reducing greenhouse gas emissions and alleviating climate change; however, the intermittent supply and large volatility of new energy power generation pose great challenges to the stable operation of the power system; for example, the output of wind energy and solar energy is significantly affected by weather conditions, and its instability requires the power system to have higher flexibility and regulation capabilities to ensure the continuity and reliability of power supply.

[0003] The coal-based semi-closed power generation cycle system, as an innovative coal-fired power generation technology, plays an important role in promoting the transformation of the energy structure; after gasifying coal and carrying out efficient combustion in a pure oxygen environment, it not only improves the combustion efficiency of the fuel, but also reduces some heat transfer links in traditional coal-fired power generation, improves the energy conversion efficiency, and can, to a certain extent, solve the problem of insufficient flexibility in traditional coal-fired power generation, enabling it to better adapt to the peak shaving requirements after new energy power generation is incorporated into the power grid.

[0004] Due to the limitations of pulverized coal combustion mode, heat transfer mechanism, and equipment design, the peak shaving rate of traditional coal-fired power generation units can usually only reach 2.5% - 4%Pe / min, far lower than the requirements of the rapid change of new energy power generation for the peak shaving rate; although the coal-based semi-closed power generation cycle system has improved the above problems to a certain extent, its performance is still restricted by factors such as the filling amount and filling speed of the working medium in the system, resulting in the variable load rate of the coal-based semi-closed power generation cycle system still being limited and the peak shaving efficiency being relatively low, making it difficult to meet the high requirements for the flexibility of the power system after large-scale integration of new energy. Summary of the Invention

[0005] Aiming at the technical problems existing in the prior art, the present invention provides a coal-based semi-closed power generation cycle system and an operation method thereof to solve the technical problems that the performance of the existing coal-based semi-closed power generation cycle system is restricted by factors such as the filling amount and filling speed of the working medium in the system, resulting in the variable load rate still being limited and the peak shaving efficiency being relatively low.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a coal-based semi-closed power generation cycle system, including a working medium circulation subsystem and a load rapid adjustment subsystem; The working fluid circulation subsystem includes a combustor, a gas turbine, a regenerator, a gas-liquid separator, a precooler and a compressor; the flue gas outlet of the combustor is connected to the inlet of the gas turbine, the outlet of the gas turbine is connected to the hot-side inlet of the regenerator, and the hot-side outlet of the regenerator is connected to the inlet of the gas-liquid separator; the gas-phase outlet of the gas-liquid separator is connected to the inlet of the precooler, and the outlet of the precooler is connected to the inlet of the compressor; the outlet of the compressor is connected to the cold-side inlet of the regenerator, and the cold-side outlet of the regenerator is connected to the circulation working fluid inlet of the combustor; The outlet of the compressor is also connected to the inlet of the load rapid regulation subsystem, and the outlet of the load rapid regulation subsystem is connected to the inlet of the gas-liquid separator; wherein, the load rapid regulation subsystem is used to store the carbon dioxide working fluid delivered by the compressor or to deliver the carbon dioxide working fluid to the gas-liquid separator.

[0007] Further, the load rapid regulation subsystem includes a high-pressure valve, a high-pressure tank and a throttle valve; The outlet of the compressor is connected to the inlet of the high-pressure tank, and the outlet of the high-pressure tank is connected to the inlet of the gas-liquid separator; The high-pressure valve is arranged between the compressor and the high-pressure tank, and the throttle valve is arranged between the high-pressure tank and the gas-liquid separator.

[0008] Further, a cooler is also included, and the cooler is arranged between the regenerator and the gas-liquid separator; wherein, the inlet of the cooler is connected to the hot-side outlet of the regenerator, and the outlet of the cooler is connected to the inlet of the gas-liquid separator.

[0009] Further, a pressure stabilizing tank is also included; the pressure stabilizing tank is arranged between the precooler and the compressor; wherein, the inlet of the pressure stabilizing tank is connected to the outlet of the precooler, and the outlet of the pressure stabilizing tank is connected to the inlet of the compressor.

[0010] Further, the outlet of the pressure stabilizing tank is also used to be connected to the inlet of the carbon capture system.

[0011] Further, a generator and a motor are also included; the generator is connected to the gas turbine through a coupling, and the motor is connected to the compressor through a coupling.

[0012] Further, a liquid-phase outlet is arranged at the bottom of the gas-liquid separator; wherein, the liquid-phase outlet is used to discharge the water formed by the condensation of the flue gas.

[0013] Further, the volume of the high-pressure tank is 20%-25% of the volume of the working fluid circulation subsystem.

[0014] The present invention also provides an operation method for a coal-based semi-closed power generation cycle system, including a normal operation mode and a variable load operation mode; In the normal operation mode, the working fluid circulation subsystem operates normally, and the load rapid adjustment subsystem is shut down; In the variable load operation mode, both the working fluid circulation subsystem and the load rapid adjustment subsystem operate normally.

[0015] Furthermore, the variable load operation mode includes a load increasing operation condition and a load decreasing operation condition; Under the load increasing operation condition, the load rapid adjustment subsystem is used to transport carbon dioxide working fluid to the gas-liquid separator (6); under the load decreasing operation condition, the load rapid adjustment subsystem is used to store the carbon dioxide working fluid transported by the compressor (9).

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The coal-based semi-closed power generation cycle system provided by the present invention realizes the rapid adjustment of the carbon dioxide working fluid in the cycle system by setting a load rapid adjustment subsystem to store the carbon dioxide working fluid transported by the compressor or transport the carbon dioxide working fluid to the gas-liquid separator by the load rapid adjustment subsystem, and further realizes the rapid variable load operation of the system, greatly improving the peak shaving efficiency of the system; specifically, when it is necessary to increase the load, the load rapid adjustment subsystem is used to transport the carbon dioxide working fluid to the gas-liquid separator, so that the carbon dioxide working fluid participating in the cycle increases, the inlet pressure of the compressor increases, the back pressure in the cycle system rises, the output of the compressor increases, and at the same time, by means of increasing the compressor speed and increasing the fuel quantity, rapid load increase is realized; when it is necessary to decrease the load, the load rapid adjustment subsystem is used to store the carbon dioxide working fluid transported by the compressor, so that the carbon dioxide working fluid participating in the cycle decreases, the inlet pressure of the compressor decreases, the back pressure in the cycle system decreases, the output of the compressor decreases, and at the same time, by means of decreasing the compressor speed and reducing the fuel quantity, rapid load decrease is realized. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a structural block diagram of the coal-based semi-closed power generation cycle system provided for the embodiment.

[0019] Among them, 1 is a burner, 2 is a gas turbine, 3 is a generator, 4 is a recuperator, 5 is a cooler, 6 is a gas-liquid separator, 7 is a pre-cooler, 8 is a pressure stabilizing tank, 9 is a compressor, 10 is a motor, 11 is a high-pressure valve, 12 is a high-pressure tank, and 13 is a throttle valve. Specific implementation manner

[0020] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer and more understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application; obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present application.

[0021] The present invention provides a coal-based semi-closed power generation cycle system, including a working medium circulation subsystem and a load rapid regulation subsystem; the working medium circulation subsystem includes a burner 1, a gas turbine 2, a recuperator 4, a gas-liquid separator 6, a pre-cooler 7 and a compressor 9; the flue gas outlet of the burner 1 is connected to the inlet of the gas turbine 2, the outlet of the gas turbine 2 is connected to the hot side inlet of the recuperator 4, and the hot side outlet of the recuperator 4 is connected to the inlet of the gas-liquid separator 6; the gas phase outlet of the gas-liquid separator 6 is connected to the inlet of the pre-cooler 7, the outlet of the pre-cooler 7 is connected to the inlet of the compressor 9; the outlet of the compressor 9 is connected to the cold side inlet of the recuperator 4, and the cold side outlet of the recuperator 4 is connected to the circulating working medium inlet of the burner 1; the outlet of the compressor 9 is also connected to the inlet of the load rapid regulation subsystem, and the outlet of the load rapid regulation subsystem is connected to the inlet of the gas-liquid separator 6; among them, the load rapid regulation subsystem is used to store the carbon dioxide working medium transported by the compressor 9 or to transport the carbon dioxide working medium to the gas-liquid separator 6.

[0022] The coal-based semi-closed power generation cycle system of the present invention, during operation, includes a normal operation mode and a variable load operation mode; among them, in the normal operation mode, the working medium circulation subsystem operates normally, and the load rapid regulation subsystem stops; in the variable load operation mode, both the working medium circulation subsystem and the load rapid regulation subsystem operate normally; the variable load operation mode includes a load increase operation condition and a load decrease operation condition; in the load increase operation condition, the load rapid regulation subsystem is used to transport the carbon dioxide working medium to the gas-liquid separator 6; in the load decrease operation condition, the load rapid regulation subsystem is used to store the carbon dioxide working medium transported by the compressor 9.

[0023] In the present invention, a load rapid regulation subsystem is utilized to store the carbon dioxide working medium delivered by the compressor or deliver the carbon dioxide working medium to the gas-liquid separator, so as to rapidly regulate the carbon dioxide working medium in the circulation system, and further realize the rapid variable-load operation of the system, greatly improving the peak shaving efficiency of the system. Among them, the load rapid regulation subsystem is used to deliver the carbon dioxide working medium to the gas-liquid separator, so that the carbon dioxide working medium participating in the circulation increases, the inlet pressure of the compressor increases, the back pressure in the circulation system rises, the output of the compressor increases, and at the same time, by means of increasing the rotational speed of the compressor and increasing the fuel quantity, rapid load increase is realized; the load rapid regulation subsystem is used to store the carbon dioxide working medium delivered by the compressor, so that the carbon dioxide working medium participating in the circulation decreases, the inlet pressure of the compressor decreases, the back pressure in the circulation system decreases, the output of the compressor decreases, and at the same time, by means of decreasing the rotational speed of the compressor and reducing the fuel quantity, rapid load reduction is realized.

[0024] The following takes specific embodiments to further explain the coal-based semi-closed power generation cycle system provided by the present invention: Embodiment As shown in the Figure 1 accompanying drawings, this embodiment provides a coal-based semi-closed power generation cycle system, including a burner 1, a gas turbine 2, a regenerator 4, a cooler 5, a gas-liquid separator 6, a precooler 7, a pressure stabilizing pipe 8, a compressor 9, a motor 10, a high-pressure valve 11, a high-pressure tank 12 and a throttle valve 13.

[0025] The flue gas outlet of the burner 1 is connected to the inlet of the gas turbine 2, the syngas inlet of the burner 1 is connected to the outlet of a preset coal gasification device, and the oxygen inlet of the burner 1 is connected to the outlet of a preset oxygen source; the outlet of the gas turbine 2 is connected to the hot side inlet of the regenerator 4, and the generator 3 is connected to the gas turbine 2 through a coupling; wherein, the generator 3 is driven by the gas turbine 2 to work to output power.

[0026] The hot-side outlet of the regenerator 4 is connected to the inlet of the cooler 5, and the outlet of the cooler 5 is connected to the inlet of the gas-liquid separator 6; the gas-phase outlet of the gas-liquid separator 6 is connected to the inlet of the precooler 7, and a liquid-phase outlet is provided at the bottom of the gas-liquid separator 6; wherein, the liquid-phase outlet is used to discharge the water formed by the condensation of the flue gas; the gas-phase outlet of the gas-liquid separator 6 is connected to the inlet of the precooler 7, the outlet of the precooler 7 is connected to the inlet of the pressure stabilizing tank 8, and the outlet of the pressure stabilizing tank 8 is connected to the inlet of the compressor 9; wherein, the compressor 9 is connected to the motor 10 through a coupling, and the motor 10 consumes electric energy to drive the compressor 9 to work to compress carbon dioxide; the pressure stabilizing tank 8 is further provided with a second outlet, and the second outlet of the pressure stabilizing pipe 8 is connected to the inlet of the carbon capture system; the outlet of the compressor 9 is divided into two paths, one path is connected to the cold-side inlet of the regenerator 4, and the other path is connected to the inlet of the high-pressure valve 11.

[0027] The cold-side outlet of the regenerator 4 is connected to the circulating working fluid inlet of the burner 1.

[0028] The outlet of the high-pressure valve 11 is connected to the inlet of the high-pressure tank 12, the outlet of the high-pressure tank 12 is connected to the inlet of the throttle valve 13, and the outlet of the throttle valve 13 is connected to the inlet of the gas-liquid separator 6. It should be noted that the high-pressure valve 11, the high-pressure tank 12 and the throttle valve 13 are connected in sequence to form a load rapid adjustment subsystem, which is connected between the compressor 9 and the gas-liquid separator 6, and stores the carbon dioxide working fluid transported by the compressor 9 or transports the carbon dioxide working fluid to the gas-liquid separator 6 through the load rapid adjustment subsystem, so as to realize the rapid adjustment of the carbon dioxide working fluid circulating in the system and participate in the rapid variable load adjustment.

[0029] Working principle and operation method: In the coal-based semi-closed power generation cycle system described in this embodiment, during operation, the synthesis gas produced by the coal gasification device and the oxygen output from the oxygen source enter the burner 1 together; among them, the main components of the synthesis gas include hydrogen and carbon monoxide; after the synthesis gas burns in the burner 1, hot flue gas mainly composed of water vapor and carbon dioxide is formed; then, the hot flue gas enters the gas turbine 2 to drive the blades in the gas turbine 2 to rotate and do work; the flue gas after doing work enters the hot side of the regenerator 4 to utilize the heat in the flue gas after doing work to heat the circulating working fluid and form the cooled flue gas; among them, the circulating working fluid is carbon dioxide; then, the cooled flue gas enters the cooler 5 to condense the water vapor in the flue gas into liquid water; the cooled flue gas and water enter the gas-liquid separator 6 together. At this time, the main component of the flue gas after gas-liquid separation is carbon dioxide, and the liquid water is discharged from the liquid phase outlet at the bottom of the gas-liquid separator 6; then, the flue gas after gas-liquid separation enters the pre-cooler 7 for further cooling and then enters the pressure stabilizing tank 8; among them, the main component of the flue gas in the pressure stabilizing tank 8 is carbon dioxide, a part of which is transported to the carbon capture system for carbon capture, and the other part enters the compressor 9 for circulation; then, the flue gas in the pressure stabilizing tank 8 enters the compressor 9 for compression and pressurization, and the pressurized flue gas enters the cold side of the regenerator 4 and enters the burner 1 after heating to form a cycle.

[0030] In the coal-based semi-closed power generation cycle system described in this embodiment, in the normal operation mode, the high-pressure valve 11, the high-pressure tank 12 and the throttle valve 13 are all shut off and do not participate in the work, that is, the load rapid regulation subsystem stops, while the working fluid circulation subsystem operates normally; when rapid load change is required, that is, when the coal-based semi-closed power generation cycle system is in the variable load operation mode, the high-pressure valve 11, the high-pressure tank 12 and the throttle valve 13 are all opened to participate in the rapid variable load regulation of the system; preferably, the volume of the high-pressure tank (12) is 20%-25% of the volume of the working fluid circulation subsystem.

[0031] Specifically, when the load needs to be increased, the carbon dioxide working fluid in the high-pressure tank 12 is sent into the gas-liquid separator 6 through the throttle valve 13 after the pressure is reduced to the preset pressure value, so that the carbon dioxide working fluid participating in the circulation increases, and then the inlet pressure of the compressor 9 gradually increases to the preset pressure value; at this time, the back pressure in the circulation system increases and the output of the compressor 9 increases; at the same time, by means of increasing the speed of the compressor 9, increasing the fuel quantity and reducing the carbon capture quantity, rapid load increase is achieved.

[0032] When load reduction is required, a part of the preset high-pressure carbon dioxide working fluid in the circulation system is sent into the high-pressure tank 12 through the high-pressure valve 11, so that the amount of carbon dioxide working fluid participating in the circulation is reduced, and then the inlet pressure of the compressor 9 is reduced to the preset value; at this time, the back pressure in the circulation system is reduced, and the output of the compressor 9 is reduced; at the same time, by combining means such as reducing the speed of the compressor 9, reducing the fuel quantity, and increasing the carbon capture quantity, rapid load reduction is achieved.

[0033] In the coal-based semi-closed power generation cycle system described in this embodiment, by adding the high-pressure tank 12, the high-pressure valve 11 and the throttle valve 13 to participate in variable load regulation, rapid variable load is achieved; among them, a high-pressure tank 12 is added at the outlet of the compressor 9 to store the carbon dioxide working fluid in the circulation system, and by charging and discharging the working fluid, the amount of carbon dioxide working fluid in the system and the inlet pressure of the compressor 9 are changed, so as to change the output of the compressor 9, and by combining means such as adjusting the speed of the compressor 9 and the fuel quantity, rapid variable load of the semi-closed power generation cycle system is achieved; specifically, when load increase is required, the carbon dioxide working fluid in the high-pressure tank 12 is sent into the gas-liquid separator 6 through the throttle valve 13, the amount of carbon dioxide working fluid participating in the circulation increases, the inlet pressure of the compressor 9 increases, the back pressure in the circulation system rises, the output of the compressor 9 increases, and at the same time, by combining means such as increasing the speed of the compressor, increasing the fuel quantity, and reducing the carbon capture quantity, rapid load increase is achieved; when load reduction is required, a part of the high-pressure carbon dioxide working fluid in the circulation system is sent into the high-pressure tank 12 through the high-pressure valve 11, the amount of carbon dioxide working fluid participating in the circulation is reduced, the inlet pressure of the compressor 9 is reduced, the back pressure in the circulation system is reduced, the output of the compressor 9 is reduced, and at the same time, by combining means such as reducing the speed of the compressor 9, reducing the fuel quantity, and increasing the carbon capture quantity, rapid load reduction is achieved.

[0034] In the coal-based semi-closed power generation cycle system described in the present invention, by introducing a rapid load regulation subsystem, the rapid load regulation subsystem stores or releases carbon dioxide working fluid, so that the system can rapidly adjust the load within a short time to adapt to changes in power demand.

[0035] In the present invention, the working fluid circulation subsystem recovers the heat of the flue gas discharged from the gas turbine through the regenerator, which is used to preheat the working fluid entering the compressor, improving the energy utilization efficiency; the setting of the cooler further reduces the temperature of the flue gas, which is beneficial to gas-liquid separation and improves the overall efficiency of the system; the addition of the pressure stabilizing tank helps to stabilize the system pressure, reduces the impact of pressure fluctuations on the system operation, and improves the stability and reliability of the system; the high-pressure tank, as the core component of the rapid load regulation subsystem, can store a large amount of carbon dioxide working fluid, providing a stable working fluid supply and regulation ability for the system; the liquid phase outlet provided at the bottom of the gas-liquid separator is used to discharge the water formed by the condensation of the flue gas, realizing the recovery and utilization of water resources; the outlet of the pressure stabilizing tank can also be connected to the carbon capture system, further reducing carbon emissions and improving the environmental protection performance of the system.

[0036] The system described in the present invention supports the normal operation mode and the variable load operation mode, and can flexibly adjust the operation state according to different power demands. Among them, the variable load operation mode includes two working conditions: load increase and load decrease. Through the storage and release functions of the load rapid adjustment subsystem, the rapid adjustment of the system load is realized, and the purpose of effectively improving the flexibility, efficiency, stability, reliability, environmental protection and economy of the system is achieved to meet the requirements of modern power systems for high efficiency, flexibility, environmental protection and reliability. At the same time, the system also has a variety of operation modes and can be flexibly adjusted according to different power demands, having broad application prospects and market value.

[0037] The above embodiments are only one of the implementation manners capable of realizing the technical solution of the present invention. The scope of protection required by the present invention is not limited only by this embodiment, but also includes any changes, substitutions and other implementation manners that are easily conceivable by those skilled in the art within the technical scope disclosed by the present invention.

Claims

1. A coal-based semi-closed power generation cycle system, characterized in that: It includes working fluid circulation subsystem and load rapid adjustment subsystem; The working medium circulation subsystem comprises a burner (1), a gas turbine (2), a regenerator (4), a gas-liquid separator (6), a precooler (7) and a compressor (9); the flue gas outlet of the burner (1) is connected to the inlet of the gas turbine (2), the outlet of the gas turbine (2) is connected to the hot side inlet of the regenerator (4), the hot side outlet of the regenerator (4) is connected to the inlet of the gas-liquid separator (6); the gas phase outlet of the gas-liquid separator (6) is connected to the inlet of the precooler (7), the outlet of the precooler (7) is connected to the inlet of the compressor (9); the outlet of the compressor (9) is connected to the cold side inlet of the regenerator (4), the cold side outlet of the regenerator (4) is connected to the circulating working medium inlet of the burner (1); The outlet of the compressor (9) is also connected to the inlet of the load rapid adjustment subsystem, and the outlet of the load rapid adjustment subsystem is connected to the inlet of the gas-liquid separator (6); wherein the load rapid adjustment subsystem is used to store the carbon dioxide working medium delivered by the compressor (9), or to deliver the carbon dioxide working medium to the gas-liquid separator (6).

2. A coal-based semi-closed power generation cycle system according to claim 1, characterized in that: The load rapid adjustment subsystem comprises a high-pressure valve (11), a high-pressure tank (12) and a throttle valve (13); The outlet of the compressor (9) is connected to the inlet of the high-pressure tank (12), and the outlet of the high-pressure tank (12) is connected to the inlet of the gas-liquid separator (6); The high-pressure valve (11) is arranged between the compressor (9) and the high-pressure tank (12), and the throttle valve (13) is arranged between the high-pressure tank (12) and the gas-liquid separator (6).

3. A coal-based semi-closed power generation cycle system according to claim 1, characterized in that: It also comprises a cooler (5), which is arranged between the regenerator (4) and the gas-liquid separator (6); wherein the inlet of the cooler (5) is connected to the hot side outlet of the regenerator (4), and the outlet of the cooler (5) is connected to the inlet of the gas-liquid separator (6).

4. A coal-based semi-closed power generation cycle system according to claim 1, characterized in that: It also includes a pressure stabilizing tank (8); the pressure stabilizing tank (8) is arranged between the precooler (7) and the compressor (9); wherein the inlet of the pressure stabilizing tank (8) is connected to the outlet of the precooler (7), and the outlet of the pressure stabilizing tank (8) is connected to the inlet of the compressor (9).

5. A coal-based semi-closed power generation cycle system according to claim 4, characterized in that: The outlet of the surge tank (8) is also used to be connected to the inlet of the carbon capture system.

6. A coal-based semi-closed power generation cycle system according to claim 1, characterized in that: It also includes a generator (3) and an electric motor (10); the generator (3) is connected to the gas turbine (2) via a coupling, and the electric motor (10) is connected to the compressor (9) via a coupling.

7. A coal-based semi-closed power generation cycle system according to claim 1, characterized in that: The bottom of the gas-liquid separator (6) is provided with a liquid phase outlet; wherein the liquid phase outlet is used to discharge water formed by condensation of flue gas.

8. A coal-based semi-closed power generation cycle system according to claim 2, characterized in that: The volume of the high-pressure tank (12) is 20%-25% of the volume of the working fluid circulation subsystem.

9. The method for operating a coal-based semi-closed power generation cycle system according to any one of claims 1 to 8, characterized in that: Including normal operation mode and variable load operation mode; In the normal operation mode, the working fluid circulation subsystem operates normally, and the load rapid adjustment subsystem shuts down; In the variable load operation mode, the working fluid circulation subsystem and the load rapid adjustment subsystem both operate normally.

10. The method for operating a coal-based semi-closed power generation cycle system according to claim 9, characterized in that: The variable load operation mode includes load-increasing operation condition and load-reducing operation condition; Under the load-raising operation condition, the load rapid adjustment subsystem is used to transport the carbon dioxide working medium to the gas-liquid separator (6); Under load-reducing operating conditions, the rapid load adjustment subsystem is used to store the carbon dioxide working fluid delivered by the compressor (9).

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