A coal-fired power plant and plasma gasification coupled electricity-methanol co-production system

Abstract

This invention provides a coal-fired power plant coupled with plasma gasification for cogeneration of methanol, belonging to the field of energy utilization. The system includes: a coal-fired power generation system for producing electricity by burning coal and emitting flue gas; a plasma gasification subsystem connected to the coal-fired power generation system for plasma gasification of solid waste to produce syngas; a carbon capture subsystem connected to both the coal-fired power generation system and the plasma gasification subsystem for decarbonizing the flue gas emitted from the coal-fired power generation system, absorbing carbon dioxide from the flue gas, emitting carbon dioxide gas, and exchanging heat with the plasma gasification subsystem; and a methanol synthesis subsystem connected to both the plasma gasification subsystem and the carbon capture subsystem for producing methanol based on syngas and carbon dioxide gas. This invention improves power generation efficiency and energy utilization.

Description

Technical Field

[0001] This invention relates to the field of energy utilization, and in particular to an electro-methanol cogeneration system that combines carbon capture and peak shaving with plasma gasification. Background Technology

[0002] The continued emission of greenhouse gases has led to a series of environmental problems, including global warming and sea-level rise. Mitigating global climate change has become a broad consensus in the international community. Of the various greenhouse gases contributing to climate change, carbon dioxide accounts for more than 50%. Carbon emissions mainly come from the combustion of fossil fuels, with coal-fired power plants accounting for approximately 40% of total carbon dioxide emissions. Since coal-fired power plants will remain the main source of electricity supply for a considerable period, research on carbon dioxide capture from coal-fired power plants is of great significance for achieving the strategic goals of dual carbon emissions.

[0003] Carbon capture technology can separate greenhouse gases such as carbon dioxide from exhaust gases during coal combustion and store or utilize them. Therefore, carbon capture technology in coal-fired power plants aims to mitigate global climate change, reduce greenhouse gas emissions, and promote the transition to clean energy. Because post-combustion carbon capture schemes require minimal modification to existing thermal power units, have good technological continuity, and offer advantages such as low operating pressure, low investment cost, and mature technology, post-combustion carbon capture schemes have become the mainstream carbon capture method in current coal-fired power plants.

[0004] Currently, waste incineration is the most common method in waste treatment. Due to its low cost, high efficiency, and good treatment results, it is widely used. However, it produces large amounts of toxic gases and fly ash during combustion, causing serious damage to the urban environment. Therefore, solid waste plasma gasification technology has come into focus. Driven by electricity, the plasma gasification furnace generates a plasma torch with temperatures exceeding 6000℃ to treat solid waste. The organic matter in the waste is converted into combustible high-temperature syngas, while the inorganic portion is discharged from the bottom of the furnace as glassy slag. This process not only treats solid waste but also achieves effective utilization of waste resources.

[0005] Faced with ever-increasing electricity demand and the challenges of energy transition, how to meet load changes and regulate the power generation end to ensure stable grid operation has become an urgent problem to be solved. In the traditional energy structure, large-scale thermal power plants are the main power generation method. In recent years, the large-scale and unstable integration of renewable energy into the grid has led to frequent start-ups and shutdowns, posing a significant threat to the safe and stable operation of coal-fired power plant boilers. Summary of the Invention

[0006] The purpose of this invention is to provide a coal-fired power plant coupled with plasma gasification for cogeneration of methanol, which can improve power generation efficiency and energy utilization.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A coal-fired power plant coupled with plasma gasification for cogeneration of methanol includes:

[0009] A coal-fired power generation system is used to generate electricity by burning coal and to exhaust flue gas.

[0010] The plasma gasification subsystem is connected to the coal-fired power generation system and is used to perform plasma gasification on solid waste to produce syngas.

[0011] A carbon capture subsystem is connected to both the coal-fired power generation system and the plasma gasification subsystem. It is used to decarbonize the flue gas discharged from the coal-fired power generation system, absorb carbon dioxide from the flue gas, discharge carbon dioxide gas, and exchange heat with the plasma gasification subsystem.

[0012] A methanol synthesis subsystem is connected to the plasma gasification subsystem and the carbon capture subsystem, respectively, for preparing methanol based on the synthesis gas and the carbon dioxide gas.

[0013] Optionally, the coal-fired power generation system includes: a coal-fired boiler, a steam turbine, a generator, a condenser, a condensate pump, and coal-fired regenerative components;

[0014] The main steam outlet of the coal-fired boiler is connected to the inlet of the steam turbine; the outlet of the steam turbine is connected to the generator, the inlet of the coal-fired boiler, the inlet of the condenser, and the inlet of the coal-fired regenerative component; the inlet of the condenser is also connected to the coal-fired regenerative component, and the outlet of the condenser is connected to the inlet of the condensate pump; the outlet of the condensate pump is connected to the inlet of the coal-fired regenerative component; the outlet of the coal-fired regenerative component is connected to the inlet of the coal-fired boiler and the plasma gasification subsystem.

[0015] The coal-fired boiler is used to burn coal to generate main steam; the main steam expands and works inside the steam turbine to drive the generator to generate electricity; the exhaust steam from the steam turbine enters both the coal-fired boiler and the condenser; the condenser is used to condense the exhaust steam from the steam turbine to obtain condensate; the condensate pump is used to pressurize the condensate; the coal-fired regenerative component is used to absorb the heat from the pressurized condensate; the drainage from the coal-fired regenerative component is heated by the plasma gasification subsystem before entering the coal-fired boiler.

[0016] Optionally, the steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder.

[0017] The main steam outlet of the coal-fired boiler is connected to the inlet of the high-pressure cylinder of the steam turbine and the inlet of the intermediate-pressure cylinder of the steam turbine, respectively; the exhaust port of the high-pressure cylinder of the steam turbine is connected to the inlet of the coal-fired boiler, the inlet of the coal-fired regenerative component, and the inlet of the intermediate-pressure cylinder of the steam turbine, respectively; the exhaust port of the intermediate-pressure cylinder of the steam turbine is connected to the inlet of the coal-fired boiler, the inlet of the coal-fired regenerative component, and the inlet of the low-pressure cylinder of the steam turbine, respectively; the exhaust port of the low-pressure cylinder of the steam turbine is connected to the generator and the inlet of the coal-fired regenerative component, respectively.

[0018] The exhaust steam from the high-pressure cylinder and the intermediate-pressure cylinder of the steam turbine enters the coal-fired boiler for reheat circulation; the exhaust steam from the low-pressure cylinder of the steam turbine enters the condenser for condensation.

[0019] Optionally, the coal-fired regenerative component includes a first low-pressure heater, a second low-pressure heater, a third low-pressure heater, a fourth low-pressure heater, a deaerator, a feed water pump, a first high-pressure heater, a second high-pressure heater, and a third high-pressure heater connected in sequence.

[0020] The first low-pressure heater is also connected to the condensate pump and the condenser; the second high-pressure heater is also connected to the plasma gasification subsystem; and the third high-pressure heater is also connected to the coal-fired boiler.

[0021] The steam inlet of the first low-pressure heater, the steam inlet of the second low-pressure heater, the steam inlet of the third low-pressure heater, and the steam inlet of the fourth low-pressure heater are all connected to the exhaust port of the low-pressure cylinder of the steam turbine.

[0022] The steam inlet of the first high-pressure heater and the steam inlet of the deaerator are both connected to the exhaust port of the intermediate-pressure cylinder of the steam turbine; the steam inlet of the second high-pressure heater and the steam inlet of the third high-pressure heater are both connected to the exhaust port of the high-pressure cylinder of the steam turbine.

[0023] Optionally, the plasma gasification subsystem includes: a plasma gasification furnace, a first heat exchanger, a second heat exchanger, and a three-way valve;

[0024] The inlet of the plasma gasification furnace is connected to the coal-fired power generation system;

[0025] The inlet of the first heat exchanger is connected to the outlet of the plasma gasification furnace and the coal-fired power generation system, respectively; the outlet of the first heat exchanger is connected to the inlet of the second heat exchanger and the coal-fired power generation system, respectively; the inlet of the second heat exchanger is also connected to the carbon capture subsystem; the outlet of the second heat exchanger is connected to the carbon capture subsystem and the three-way valve, respectively; the three-way valve is also connected to the coal-fired power generation system and the methanol synthesis subsystem, respectively.

[0026] The plasma gasifier is used to perform plasma gasification on solid waste under the action of the electrical energy generated by the coal-fired power generation system to produce preliminary syngas; the preliminary syngas is sequentially passed through the first heat exchanger and the second heat exchanger for heat exchange to obtain syngas; the three-way valve is used to control the syngas to enter the coal-fired power generation system for power generation and / or enter the methanol synthesis subsystem for methanol production.

[0027] Optionally, the carbon capture subsystem includes: a fan, an electrostatic precipitator, a desulfurization tower, an absorption tower, a third heat exchanger, a desorption tower, a reboiler, and a first separator;

[0028] The blower, the electrostatic precipitator, the desulfurization tower, the absorption tower, the third heat exchanger, the desorption tower, and the first separator are connected in sequence; the blower is also connected to the coal-fired power generation system; the first separator is also connected to the methanol synthesis subsystem; the reboiler is connected to the desorption tower, the third heat exchanger, and the plasma gasification subsystem respectively.

[0029] The flue gas discharged from the coal-fired power generation system enters the electrostatic precipitator, the desulfurization tower and the absorption tower in sequence under the action of the fan;

[0030] The electrostatic precipitator is used to perform electrostatic dust removal on the flue gas discharged from the coal-fired power generation system;

[0031] The desulfurization tower is used to desulfurize the flue gas after dust removal;

[0032] The absorption tower is used to decarbonize the flue gas after desulfurization, and uses MEA solution to absorb carbon dioxide in the flue gas after desulfurization to obtain a carbon dioxide-rich MEA solution.

[0033] The third heat exchanger is used to exchange heat with the carbon dioxide-rich MEA solution.

[0034] The desorption tower is used to desorb the carbon dioxide-rich MEA solution after heat exchange. The desorbed gas enters the first separator, and the desorbed liquid enters the reboiler.

[0035] The first separator is used to separate carbon dioxide gas from the desorbed gas and deliver it to the methanol synthesis subsystem.

[0036] Optionally, the carbon capture subsystem further includes: a first pump and a second pump;

[0037] The first pump is connected to both the absorption tower and the third heat exchanger; the first pump is used to feed the carbon dioxide-rich MEA solution into the third heat exchanger.

[0038] The second pump is connected to the third heat exchanger and the reboiler respectively; the second pump is used to send liquid from the reboiler into the third heat exchanger.

[0039] Optionally, the methanol synthesis subsystem includes: a compressor, a heater, a first mixer, a methanol reactor, a condenser, a flash evaporator, a second separator, a fractionation column, and a second mixer;

[0040] The compressor inlet is connected to both the carbon capture subsystem and the plasma vaporization subsystem; the compressor outlet is connected to the heater inlet; the heater outlet is connected to the inlet of the first mixer; the first mixer outlet is connected to the methanol reactor inlet; the methanol reactor outlet is connected to the condenser inlet; the condenser outlet is connected to the flash evaporator inlet; the flash evaporator outlet is connected to both the second separator inlet and the fractionation tower inlet; the second separator outlet is connected to both the second mixer inlet and the first mixer inlet; the fractionation tower outlet is connected to the second mixer inlet.

[0041] The compressor is used to pressurize the mixture of the synthesis gas and the carbon dioxide gas to obtain a pressurized mixture. The pressurized mixture is heated by the heater and then enters the methanol reactor through the first mixer to produce methanol. The liquid discharged from the methanol reactor is condensed in the condenser and then discharged into the flash evaporator for flash evaporation. The gas discharged from the flash evaporator is separated by the second separator to obtain carbon dioxide and waste gas. The carbon dioxide separated by the second separator enters the first mixer. The methanol liquid discharged from the flash evaporator enters the fractionation tower for distillation to obtain methanol. The waste gas from the fractionation section of the fractionation tower and the waste gas separated by the second separator enter the second mixer and are discharged in the form of purge gas.

[0042] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0043] This invention integrates a coal-fired power generation system, a plasma gasification subsystem, a carbon capture subsystem, and a methanol synthesis subsystem. It effectively treats solid waste using plasma gasification, decarbonizes the flue gas emitted from the coal-fired power generation system using the carbon capture subsystem, and produces methanol based on syngas and carbon dioxide gas using the methanol synthesis subsystem. This improves the power generation efficiency and energy utilization rate of the coal-fired power generation system. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0045] Figure 1 This is a schematic diagram of an electro-methanol cogeneration system coupled with plasma gasification, provided by the present invention.

[0046] Symbol explanation:

[0047] 1-Coal-fired boiler, 2-High-pressure cylinder of steam turbine, 3-Intermediate-pressure cylinder of steam turbine, 4-Low-pressure cylinder of steam turbine, 5-Generator, 6-Condenser, 7-Condensate pump, 8-First low-pressure heater, 9-Second low-pressure heater, 10-Third low-pressure heater, 11-Fourth low-pressure heater, 12-Deaerator, 13-Feed water pump, 14-First high-pressure heater, 15-Second high-pressure heater, 16-Third high-pressure heater, 17-Plasma gasifier, 18-First heat exchanger, 19- Second heat exchanger, 20-three-way valve, 21-fan, 22-electrostatic precipitator, 23-desulfurization tower, 24-absorption tower, 25-chimney, 26-first pump, 27-third heat exchanger, 28-desorption tower, 29-reboiler, 30-second pump, 31-first separator, 32-compressor, 33-heater, 34-first mixer, 35-methanol reactor, 36-condenser, 37-flash evaporator, 38-fractionation tower, 39-second separator, 40-second mixer. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The purpose of this invention is to provide an electro-methanol cogeneration system coupled with a coal-fired power plant and plasma gasification. By integrating a coal-fired power generation system, a plasma gasification subsystem, a carbon capture subsystem, and a methanol synthesis subsystem, the system effectively treats solid waste using plasma gasification. Through the regulation of a three-way valve, syngas is introduced into the coal-fired boiler during peak electricity demand periods to increase power generation, and during off-peak periods, syngas is introduced into the methanol synthesis subsystem to produce methanol. Simultaneously, the carbon capture subsystem decarbonizes the flue gas from the coal-fired boiler, providing a feasible method for treating solid waste and promoting energy utilization.

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] like Figure 1 As shown, the coal-fired power plant coupled with plasma gasification and the power-methanol cogeneration system provided by the present invention includes: a coal-fired power generation system, a plasma gasification subsystem, a carbon capture subsystem, and a methanol synthesis subsystem.

[0052] Coal-fired power generation systems are used to generate electricity by burning coal and to exhaust flue gas.

[0053] Specifically, the coal-fired power generation system includes: a coal-fired boiler 1, a steam turbine, a generator 5, a condenser 6, a condensate pump 7, and coal-fired regenerative components.

[0054] The steam turbine includes a high-pressure cylinder 2, an intermediate-pressure cylinder 3, and a low-pressure cylinder 4. The high-pressure cylinder 2, intermediate-pressure cylinder 3, low-pressure cylinder 4, and generator 5 are coaxially connected in sequence.

[0055] The coal-fired reheating component includes a first low-pressure heater 8, a second low-pressure heater 9, a third low-pressure heater 10, a fourth low-pressure heater 11, a deaerator 12, a water pump 13, a first high-pressure heater 14, a second high-pressure heater 15, and a third high-pressure heater 16 connected in sequence.

[0056] The main steam outlet of the coal-fired boiler 1 is connected to the inlet of the steam turbine. The outlet of the steam turbine is connected to the generator 5, the inlet of the coal-fired boiler 1, the inlet of the condenser 6, and the inlet of the coal-fired regenerative component. The inlet of the condenser 6 is also connected to the coal-fired regenerative component, and the outlet of the condenser 6 is connected to the inlet of the condensate pump 7. The outlet of the condensate pump 7 is connected to the inlet of the coal-fired regenerative component. The outlet of the coal-fired regenerative component is connected to the inlet of the coal-fired boiler 1 and the plasma gasification subsystem.

[0057] Specifically, the main steam outlet of the coal-fired boiler 1 is connected to the inlet of the high-pressure cylinder 2 of the steam turbine and the inlet of the intermediate-pressure cylinder 3 of the steam turbine, respectively. The exhaust port of the high-pressure cylinder 2 of the steam turbine is connected to the inlet of the coal-fired boiler 1, the inlet of the coal-fired regenerative component, and the inlet of the intermediate-pressure cylinder 3 of the steam turbine, respectively. The exhaust port of the intermediate-pressure cylinder 3 of the steam turbine is connected to the inlet of the coal-fired boiler 1, the inlet of the coal-fired regenerative component, and the inlet of the low-pressure cylinder 4 of the steam turbine, respectively. The exhaust port of the low-pressure cylinder 4 of the steam turbine is connected to the inlet of the generator 5 and the inlet of the coal-fired regenerative component, respectively.

[0058] The first low-pressure heater 8 is also connected to the condensate pump 7 and the condenser 6. The second high-pressure heater 15 is also connected to the plasma gasification subsystem. The third high-pressure heater 16 is also connected to the coal-fired boiler 1. The outlet feedwater of the third high-pressure heater 16 enters the coal-fired boiler 1.

[0059] The steam inlet of the first low-pressure heater 8, the steam inlet of the second low-pressure heater 9, the steam inlet of the third low-pressure heater 10, and the steam inlet of the fourth low-pressure heater 11 are all connected to the exhaust port of the turbine low-pressure cylinder 4.

[0060] The steam inlet of the first high-pressure heater 14 and the steam inlet of the deaerator 12 are both connected to the exhaust port of the intermediate-pressure cylinder 3 of the steam turbine. The steam inlet of the second high-pressure heater 15 and the steam inlet of the third high-pressure heater 16 are both connected to the exhaust port of the high-pressure cylinder 2 of the steam turbine.

[0061] The exhaust steam from the low-pressure cylinder 4 of the steam turbine provides heat to the four low-pressure heaters. The condensate from the outlet of the fourth low-pressure heater 11 enters the deaerator 12. The exhaust steam from the intermediate-pressure cylinder 3 of the steam turbine serves as the heat source for the deaerator 12. The water at the outlet of the deaerator 12, after being pressurized by the feedwater pump 13, flows sequentially through the first high-pressure heater 14, the second high-pressure heater 15, and the third high-pressure heater 16, before entering the coal-fired boiler 1. The exhaust steam from the intermediate-pressure cylinder 3 of the steam turbine serves as the heat source for the first high-pressure heater 14, and the exhaust steam from the high-pressure cylinder 2 of the steam turbine serves as the heat source for the second high-pressure heater 15 and the third high-pressure heater 16. The condensate from each heater flows by gravity into the next stage heater.

[0062] The coal-fired boiler 1 is used to burn coal to generate main steam. The main steam expands and works within the steam turbine to drive the generator 5 to generate electricity. The exhaust steam from the steam turbine enters both the coal-fired boiler 1 and the condenser 6. The condenser 6 is used to condense the exhaust steam from the steam turbine to obtain condensate. The exhaust steam from the high-pressure cylinder 2 and the intermediate-pressure cylinder 3 of the steam turbine enters the coal-fired boiler 1 for reheat circulation. The exhaust steam from the low-pressure cylinder 4 of the steam turbine enters the condenser 6 for condensation. The condensate pump 7 is used to pressurize the condensate. The coal-fired regenerative component is used to absorb the heat from the pressurized condensate. Specifically, the pressurized condensate sequentially passes through a first low-pressure heater 8, a second low-pressure heater 9, a third low-pressure heater 10, and a fourth low-pressure heater 11 to absorb heat. The drainage from the coal-fired regenerative component is heated by the plasma gasification subsystem before entering the coal-fired boiler 1.

[0063] Specifically, the drainage from the second high-pressure heater 15 is heated by the first heat exchanger 18 using the high-temperature synthesis gas generated by the plasma gasification subsystem as a heat source. The heated drainage is then mixed with the drainage from the second high-pressure heater 15, thus achieving coupling between the systems.

[0064] The coal-fired power generation system uses coal as its main energy source. During peak electricity consumption periods, the syngas from the plasma gasification subsystem is fed into the coal-fired boiler 1 for combustion, increasing the main steam parameters to produce more electricity. After absorbing heat in the coal-fired boiler 1, the main steam sequentially enters the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 of the turbine, where it expands and performs work, driving the generator 5 to generate electricity.

[0065] The plasma gasification subsystem is connected to the coal-fired power generation system. The plasma gasification subsystem is used to perform plasma gasification on solid waste to produce syngas.

[0066] Specifically, the plasma gasification subsystem includes: a plasma gasification furnace 17, a first heat exchanger 18, a second heat exchanger 19, and a three-way valve 20.

[0067] The inlet of the plasma gasification furnace 17 is connected to the coal-fired power generation system.

[0068] The inlet of the first heat exchanger 18 is connected to the outlet of the plasma gasifier 17 and the coal-fired power generation system. The outlet of the first heat exchanger 18 is connected to the inlet of the second heat exchanger 19 and the coal-fired power generation system. The inlet of the second heat exchanger 19 is also connected to the carbon capture subsystem. The outlet of the second heat exchanger 19 is connected to the carbon capture subsystem and the three-way valve 20. The three-way valve 20 is also connected to the compressor 32 in both the coal-fired power generation system and the methanol synthesis subsystem.

[0069] The plasma gasifier 17 is used to plasma gasify solid waste under the influence of electrical energy generated by the coal-fired power generation system to produce preliminary syngas. The preliminary syngas passes sequentially through the first heat exchanger 18 and the second heat exchanger 19 for heat exchange, resulting in syngas. The heat released by the plasma gasifier 17 is absorbed by the drainage extracted by the second high-pressure heater 15 in the first heat exchanger 18. The syngas leaving the first heat exchanger 18 enters the second heat exchanger 19, where the released heat is absorbed by the reboiler 29. The second heat exchanger 19 heats both the drainage extracted by the second high-pressure heater 15 and the solution in the reboiler 29. The cooled syngas then enters the inlet of the three-way valve 20. The three-way valve 20 controls the syngas to enter the coal-fired power generation system for power generation and / or the methanol synthesis subsystem for methanol production.

[0070] During peak electricity consumption periods, the three-way valve 20 is adjusted to allow syngas to enter the coal-fired boiler 1 to increase power generation. During off-peak electricity consumption periods, the three-way valve 20 is adjusted to allow syngas to enter the methanol synthesis subsystem for methanol production, thereby achieving peak shaving.

[0071] In this embodiment, solid waste enters the plasma gasification furnace 17, where the organic components are converted into syngas, and the inorganic waste is discharged from the bottom of the plasma gasification furnace 17 in the form of glassy slag. The high-temperature syngas generated from the organic matter is then exchanged for heat through the first heat exchanger 18 and the second heat exchanger 19, thereby realizing the cascade utilization of the high-temperature syngas energy.

[0072] The carbon capture subsystem is connected to both the coal-fired power generation system and the plasma gasification subsystem. The carbon capture subsystem is used to decarbonize the flue gas discharged from the coal-fired power generation system, absorb carbon dioxide from the flue gas, discharge carbon dioxide gas, and exchange heat with the plasma gasification subsystem.

[0073] Specifically, the carbon capture subsystem includes: a fan 21, an electrostatic precipitator 22, a desulfurization tower 23, an absorption tower 24, a third heat exchanger 27, a desorption tower 28, a reboiler 29, and a first separator 31.

[0074] The blower 21, the electrostatic precipitator 22, the desulfurization tower 23, the absorption tower 24, the third heat exchanger 27, the desorption tower 28, and the first separator 31 are connected in sequence. Specifically, the blower 21 is also connected to the coal-fired power generation system. The first separator 31 is also connected to the methanol synthesis subsystem. The reboiler 29 is connected to the desorption tower 28, the third heat exchanger 27, and the plasma gasification subsystem, respectively. The top of the desorption tower 28 is connected to the first separator 31, and the bottom is connected to the reboiler 29.

[0075] Furthermore, the carbon capture subsystem also includes a chimney 25. The absorption tower 24 is connected to the chimney 25.

[0076] The flue gas discharged from the coal-fired power generation system enters the electrostatic precipitator 22, the desulfurization tower 23 and the absorption tower 24 in sequence under the action of the fan 21.

[0077] The electrostatic precipitator 22 is used to perform electrostatic dust removal on the flue gas discharged from the coal-fired power generation system.

[0078] The desulfurization tower 23 is used to desulfurize the flue gas after dust removal.

[0079] The absorption tower 24 is used to decarbonize the desulfurized flue gas and uses MEA solution to absorb the carbon dioxide in the desulfurized flue gas, resulting in a carbon dioxide-rich MEA solution. The decarbonized flue gas is discharged from the top of the absorption tower 24 and then discharged into the atmosphere through the chimney 25.

[0080] The third heat exchanger 27 is used to exchange heat with the carbon dioxide-rich MEA solution.

[0081] The desorption tower 28 is used to desorb the carbon dioxide-rich MEA solution after heat exchange. The desorbed gas enters the first separator 31, and the desorbed liquid enters the reboiler 29.

[0082] The first separator 31 is used to separate carbon dioxide gas from the desorbed gas and deliver it to the methanol synthesis subsystem.

[0083] Furthermore, the carbon capture subsystem also includes a first pump 26 and a second pump 30.

[0084] The first pump 26 is connected to both the absorption tower 24 and the third heat exchanger 27. The first pump 26 is used to feed the carbon dioxide-rich MEA solution into the third heat exchanger 27.

[0085] The second pump 30 is connected to both the third heat exchanger 27 and the reboiler 29. The second pump 30 is used to feed liquid from the reboiler 29 into the third heat exchanger 27.

[0086] In this embodiment, the carbon capture subsystem uses MEA solution as the absorbent to absorb carbon dioxide from the flue gas. The carbon dioxide-rich MEA solution is then pumped by the first pump 26 into the third heat exchanger 27 for heat exchange, and then into the desorption tower 28 for carbon dioxide desorption. The MEA solution in the desorption tower 28 is separated from the MEA solution by the reboiler 29, which uses the second heat exchanger 19 as a heat source. The desorbed liquid portion either enters the desorption tower 28 or, under the action of the second pump 30, flows through the third heat exchanger 27 for heat exchange before finally entering the absorption tower 24. The gas desorbed in the desorption tower 28 is separated by the first separator 31. The separated carbon dioxide gas is discharged into the compressor 32 of the methanol synthesis subsystem for methanol production. The separated MEA solution re-enters the desorption tower 28 for reaction. The heat for the reboiler 29 is provided by the high-temperature synthesis gas from the second heat exchanger 19.

[0087] The methanol synthesis subsystem is connected to the plasma gasification subsystem and the carbon capture subsystem, respectively, and is used to produce methanol based on the synthesis gas and the carbon dioxide gas.

[0088] Specifically, the methanol synthesis subsystem includes: compressor 32, heater 33, first mixer 34, methanol reactor 35, condenser 36, flash evaporator 37, second separator 39, fractionation tower 38, and second mixer 40.

[0089] The inlet of compressor 32 is connected to the second separator 39 of the carbon capture subsystem and the three-way valve 20 of the plasma vaporization subsystem. The outlet of compressor 32 is connected to the inlet of heater 33. The outlet of heater 33 is connected to the inlet of first mixer 34. The outlet of first mixer 34 is connected to the inlet of methanol reactor 35. The outlet of methanol reactor 35 is connected to the inlet of condenser 36. The outlet of condenser 36 is connected to the inlet of flash evaporator 37. The outlet of flash evaporator 37 is connected to the inlet of second separator 39 and the inlet of fractionation column 38. The outlet of second separator 39 is connected to the inlet of second mixer 40 and the inlet of first mixer 34. The outlet of fractionation column 38 is connected to the inlet of second mixer 40.

[0090] The compressor 32 is used to pressurize the mixture of syngas and carbon dioxide to obtain a pressurized mixture. The pressurized mixture is heated by the heater 33 and then enters the methanol reactor 35 through the first mixer 34 to produce methanol. The liquid discharged from the methanol reactor 35 is condensed in the condenser 36 and then discharged into the flash evaporator 37 for flash evaporation. The gas discharged from the flash evaporator 37 is separated by the second separator 39 to obtain carbon dioxide and waste gas. The carbon dioxide separated by the second separator 39 enters the first mixer 34 to participate in the tail gas recirculation. The methanol liquid discharged from the flash evaporator 37 enters the fractionation tower 38 for further purification to obtain methanol. The waste gas from the fractionation section of the fractionation tower 38 and the waste gas separated by the second separator 39 enter the second mixer 40 together and are discharged as purge gas.

[0091] This invention integrates a coal-fired power generation system, a plasma gasification subsystem, a carbon capture subsystem, and a methanol synthesis subsystem. The plasma gasifier 17, driven by electricity generated from the coal-fired power plant, gasifies the gas to produce high-temperature syngas. The heat from this syngas further heats the feedwater of the coal-fired power generation system, thereby increasing the feedwater temperature of the coal-fired boiler 1. The still-high-temperature syngas then provides heat to the reboiler 29 of the carbon capture subsystem, achieving decarbonization of the gas from the coal-fired boiler 1. While the carbon capture subsystem decarbonizes the flue gas from the coal-fired boiler 1, a three-way valve 20 regulates the flow of syngas from the plasma gasifier 17. During peak electricity demand periods, the syngas is fed into the coal-fired boiler unit and converted into electricity. During off-peak periods, it mixes with carbon dioxide obtained from carbon capture for methanol synthesis, thus achieving peak shaving. This effectively reduces the hazards caused by frequent start-ups and shutdowns of the coal-fired boiler 1 and effectively controls the treatment and emission of pollutants. The cascade utilization of high-temperature syngas thermal energy has been realized, which has improved the power generation efficiency and energy utilization rate of coal-fired boiler 1. The syngas is utilized in a targeted manner to take into account the electricity demand at different times, thereby achieving the purpose of peak shaving.

[0092] In summary, with the amount of coal consumed remaining constant, the total power generation of the coal-fired power plant coupled with plasma gasification and the power-methanol cogeneration system provided by this invention is greater than the sum of the power generation of traditional systems, and the energy of solid waste is utilized efficiently.

[0093] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A coal-fired power plant coupled with plasma gasification for cogeneration of methanol, characterized in that, The coal-fired power plant coupled with plasma gasification for power-methanol cogeneration includes: A coal-fired power generation system is used to generate electricity by burning coal and to exhaust flue gas. The plasma gasification subsystem is connected to the coal-fired power generation system and is used to perform plasma gasification on solid waste to produce syngas. A carbon capture subsystem is connected to both the coal-fired power generation system and the plasma gasification subsystem. It is used to decarbonize the flue gas discharged from the coal-fired power generation system, absorb carbon dioxide from the flue gas, discharge carbon dioxide gas, and exchange heat with the plasma gasification subsystem. A methanol synthesis subsystem is connected to the plasma gasification subsystem and the carbon capture subsystem, respectively, for preparing methanol based on the synthesis gas and the carbon dioxide gas; The plasma gasification subsystem includes: a plasma gasification furnace, a first heat exchanger, a second heat exchanger, and a three-way valve; The inlet of the plasma gasification furnace is connected to the coal-fired power generation system; The inlet of the first heat exchanger is connected to the outlet of the plasma gasification furnace and the coal-fired power generation system, respectively; the outlet of the first heat exchanger is connected to the inlet of the second heat exchanger and the coal-fired power generation system, respectively; the inlet of the second heat exchanger is also connected to the carbon capture subsystem; the outlet of the second heat exchanger is connected to the carbon capture subsystem and the three-way valve, respectively; the three-way valve is also connected to the coal-fired power generation system and the methanol synthesis subsystem, respectively. The plasma gasification furnace is used to plasma gasify solid waste under the action of electrical energy generated by the coal-fired power generation system to produce preliminary syngas. The preliminary syngas is then passed through the first heat exchanger and the second heat exchanger for heat exchange to obtain syngas. The three-way valve is used to control the syngas to enter the coal-fired power generation system for power generation and / or to enter the methanol synthesis subsystem for methanol production. Specifically, during peak electricity consumption periods, the three-way valve is adjusted to allow the syngas to enter the coal-fired boiler to increase power generation, and during off-peak electricity consumption periods, the three-way valve is adjusted to allow the syngas to enter the methanol synthesis subsystem for methanol production. The methanol synthesis subsystem includes: a compressor, a heater, a first mixer, a methanol reactor, a condenser, a flash evaporator, a second separator, a fractionation column, and a second mixer; The compressor inlet is connected to both the carbon capture subsystem and the plasma vaporization subsystem; the compressor outlet is connected to the heater inlet; the heater outlet is connected to the inlet of the first mixer; the first mixer outlet is connected to the methanol reactor inlet; the methanol reactor outlet is connected to the condenser inlet; the condenser outlet is connected to the flash evaporator inlet; the flash evaporator outlet is connected to both the second separator inlet and the fractionation tower inlet; the second separator outlet is connected to both the second mixer inlet and the first mixer inlet; the fractionation tower outlet is connected to the second mixer inlet. The compressor is used to pressurize the mixture of the synthesis gas and the carbon dioxide gas to obtain a pressurized mixture. The pressurized mixture is heated by the heater and then enters the methanol reactor through the first mixer to produce methanol. The liquid discharged from the methanol reactor is condensed in the condenser and then discharged into the flash evaporator for flash evaporation. The gas discharged from the flash evaporator is separated by the second separator to obtain carbon dioxide and waste gas. The carbon dioxide separated by the second separator enters the first mixer. The methanol liquid discharged from the flash evaporator enters the fractionation tower for fractionation to obtain methanol. The waste gas from the fractionation tower and the waste gas separated by the second separator enter the second mixer and are discharged in the form of purge gas.

2. The coal-fired power plant coupled with plasma gasification power generation system according to claim 1, characterized in that, The coal-fired power generation system includes: a coal-fired boiler, a steam turbine, a generator, a condenser, a condensate pump, and coal-fired regenerative components; The main steam outlet of the coal-fired boiler is connected to the inlet of the steam turbine; the outlet of the steam turbine is connected to the generator, the inlet of the coal-fired boiler, the inlet of the condenser, and the inlet of the coal-fired regenerative component; the inlet of the condenser is also connected to the coal-fired regenerative component, and the outlet of the condenser is connected to the inlet of the condensate pump; the outlet of the condensate pump is connected to the inlet of the coal-fired regenerative component; the outlet of the coal-fired regenerative component is connected to the inlet of the coal-fired boiler and the plasma gasification subsystem. The coal-fired boiler is used to burn coal to generate main steam; the main steam expands and works inside the steam turbine to drive the generator to generate electricity; the exhaust steam from the steam turbine enters both the coal-fired boiler and the condenser; the condenser is used to condense the exhaust steam from the steam turbine to obtain condensate; the condensate pump is used to pressurize the condensate; the coal-fired regenerative component is used to absorb the heat from the pressurized condensate; the drainage from the coal-fired regenerative component is heated by the plasma gasification subsystem before entering the coal-fired boiler.

3. The coal-fired power plant coupled with plasma gasification power generation system according to claim 2, characterized in that, The steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. The main steam outlet of the coal-fired boiler is connected to the inlet of the high-pressure cylinder of the steam turbine and the inlet of the intermediate-pressure cylinder of the steam turbine, respectively; the exhaust port of the high-pressure cylinder of the steam turbine is connected to the inlet of the coal-fired boiler, the inlet of the coal-fired regenerative component, and the inlet of the intermediate-pressure cylinder of the steam turbine, respectively; the exhaust port of the intermediate-pressure cylinder of the steam turbine is connected to the inlet of the coal-fired boiler, the inlet of the coal-fired regenerative component, and the inlet of the low-pressure cylinder of the steam turbine, respectively; the exhaust port of the low-pressure cylinder of the steam turbine is connected to the generator and the inlet of the coal-fired regenerative component, respectively. The exhaust steam from the high-pressure cylinder and the intermediate-pressure cylinder of the steam turbine enters the coal-fired boiler for reheat circulation; the exhaust steam from the low-pressure cylinder of the steam turbine enters the condenser for condensation.

4. The coal-fired power plant coupled with plasma gasification power generation system according to claim 3, characterized in that, The coal-fired regenerative component includes a first low-pressure heater, a second low-pressure heater, a third low-pressure heater, a fourth low-pressure heater, a deaerator, a water pump, a first high-pressure heater, a second high-pressure heater, and a third high-pressure heater connected in sequence. The first low-pressure heater is also connected to the condensate pump and the condenser; the second high-pressure heater is also connected to the plasma gasification subsystem; and the third high-pressure heater is also connected to the coal-fired boiler. The steam inlet of the first low-pressure heater, the steam inlet of the second low-pressure heater, the steam inlet of the third low-pressure heater, and the steam inlet of the fourth low-pressure heater are all connected to the exhaust port of the low-pressure cylinder of the steam turbine. The steam inlet of the first high-pressure heater and the steam inlet of the deaerator are both connected to the exhaust port of the intermediate-pressure cylinder of the steam turbine; the steam inlet of the second high-pressure heater and the steam inlet of the third high-pressure heater are both connected to the exhaust port of the high-pressure cylinder of the steam turbine.

5. The coal-fired power plant coupled with plasma gasification for cogeneration system according to claim 1, characterized in that, The carbon capture subsystem includes: a fan, an electrostatic precipitator, a desulfurization tower, an absorption tower, a third heat exchanger, a desorption tower, a reboiler, and a first separator; The blower, the electrostatic precipitator, the desulfurization tower, the absorption tower, the third heat exchanger, the desorption tower, and the first separator are connected in sequence; the blower is also connected to the coal-fired power generation system; the first separator is also connected to the methanol synthesis subsystem; the reboiler is connected to the desorption tower, the third heat exchanger, and the plasma gasification subsystem respectively. The flue gas discharged from the coal-fired power generation system enters the electrostatic precipitator, the desulfurization tower and the absorption tower in sequence under the action of the fan; The electrostatic precipitator is used to perform electrostatic dust removal on the flue gas discharged from the coal-fired power generation system; The desulfurization tower is used to desulfurize the flue gas after dust removal; The absorption tower is used to decarbonize the flue gas after desulfurization, and uses MEA solution to absorb carbon dioxide in the flue gas after desulfurization to obtain a carbon dioxide-rich MEA solution. The third heat exchanger is used to exchange heat with the carbon dioxide-rich MEA solution. The desorption tower is used to desorb the carbon dioxide-rich MEA solution after heat exchange. The desorbed gas enters the first separator, and the desorbed liquid enters the reboiler. The first separator is used to separate carbon dioxide gas from the desorbed gas and deliver it to the methanol synthesis subsystem.

6. The coal-fired power plant coupled with plasma gasification for cogeneration system according to claim 5, characterized in that, The carbon capture subsystem also includes: a first pump and a second pump; The first pump is connected to both the absorption tower and the third heat exchanger; the first pump is used to feed the carbon dioxide-rich MEA solution into the third heat exchanger. The second pump is connected to both the third heat exchanger and the reboiler; the second pump is used to send liquid from the reboiler into the third heat exchanger.

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