Sewage treatment plant combined cycle power generation system based on ideal Ericsson cycle principle

Abstract

The invention relates to a sewage treatment plant combined cycle power generation system based on the ideal Ericsson cycle principle. The sewage treatment plant combined cycle power generation system comprises a biogas gas turbine power generation module, an aeration tank photovoltaic power generation module, a carbon dioxide cycle power generation module and a heat storage module. The carbon dioxide cycle power generation module is based on the ideal Ericsson cycle principle, and power generation is achieved through the isothermal compression and expansion process and the isobaric heat absorption and heat release process. In the power utilization trough, carbon dioxide is compressed and stored through photovoltaic power generation or power grid trough electric power, and the carbon dioxide is heated through waste heat of the gas turbine and the heat storage module and enters the expansion machine for power generation. Compared with the prior art, the method not only optimizes the energy utilization in the sewage treatment plant, but also effectively reduces the dependence on fossil fuel, and has higher environmental benefit and economic value. A biogas gas turbine, compressed carbon dioxide cycle power generation, aeration tank photovoltaic power generation and a heat storage system are effectively combined, and efficient utilization and dynamic peak regulation of energy are achieved.

Description

Technical Field

[0001] The invention relates to the field of energy technology, and in particular to a combined cycle power generation system of a sewage treatment plant based on the ideal Ericsson cycle principle. Background Art

[0002] Sewage treatment plants produce a large amount of sludge during the sewage treatment process, and the organic matter in it will produce biogas through anaerobic fermentation. Traditional sewage treatment plants usually only use biogas as fuel for heating or directly for power generation, but this method has low energy efficiency. In addition, traditional electricity supply often relies on fossil fuels, which not only consumes non-renewable energy, but also imposes a certain burden on the environment.

[0003] With the development of renewable energy technology, photovoltaic power generation has become an effective green energy solution, but in many facilities, the space and energy conversion efficiency of photovoltaic power generation are still limited. During peak hours of electricity demand, the stability and efficiency of power supply are key issues, so it is particularly important to develop efficient energy storage systems and dynamic peak-shaving solutions.

[0004] Existing carbon dioxide cycle power generation technologies, such as the ideal Ericsson cycle, have high energy conversion efficiency in theory, but in practical applications, due to the complexity of the system and high operating costs, they have not yet been widely used in sewage treatment plants. Therefore, how to effectively combine carbon dioxide cycle power generation technology with existing sewage treatment plant resources has become the key to improving power generation efficiency and resource utilization. Summary of the invention

[0005] The purpose of the present invention is to provide a system to overcome the above-mentioned defects of the prior art. The system of the present invention not only optimizes the energy utilization in the sewage treatment plant, but also effectively reduces the dependence on fossil fuels, and has high environmental benefits and economic value. By integrating multiple power generation and energy storage technologies into one system, an efficient and environmentally friendly power generation solution is provided. The system effectively combines biogas combustion engines, compressed carbon dioxide cycle power generation, aeration tank photovoltaic power generation and heat storage systems to achieve efficient energy utilization and dynamic peak regulation.

[0006] The present invention provides a combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle, comprising: a biogas combustion engine power generation module, an aeration tank photovoltaic power generation module, a carbon dioxide cycle power generation module, and a heat storage module;

[0007] The biogas engine power generation module uses the biogas generated by the fermentation of sludge in the sewage treatment plant as fuel to drive the biogas engine to generate electricity, thereby making full use of the biogas resources generated in the sewage treatment plant.

[0008] The carbon dioxide cycle power generation module is based on the ideal Ericsson cycle principle and realizes power generation through isothermal compression and expansion, isobaric heat absorption and heat release processes. When electricity consumption is low, carbon dioxide is compressed and stored through photovoltaic power generation or grid low-peak electricity, and the waste heat of the gas turbine and the heat storage module are used to heat the carbon dioxide and enter the expander to generate electricity. The carbon dioxide cycle power generation module includes: an energy storage unit, a high-pressure expander, a low-pressure expander, a high-pressure heater, a low-pressure heater, and a generator; the high-pressure expander, the low-pressure expander, and the generator are connected in sequence; the energy storage unit includes: a high-pressure compressor, a low-pressure A compressor, a high-pressure carbon dioxide gas storage tank, and a low-pressure carbon dioxide gas storage tank; the pipelines at the flue gas outlets of the high-pressure heater and the low-pressure heater are connected to the sludge drying tank, so that the waste heat flue gas that is overheated with carbon dioxide in the heater provides corresponding heat for the sludge to be dried to meet the drying temperature conditions; a carbon dioxide and carbon dioxide heat exchanger, and a heat storage fluid and carbon dioxide heat exchanger are provided between the high-pressure heater and the energy storage unit; the pipeline at the outlet of the carbon dioxide and carbon dioxide heat exchanger is connected in series with the heat exchanger in the sludge anaerobic digestion tank, and the carbon dioxide in the pipeline provides corresponding heat for the sludge to be heated to meet the anaerobic digestion conditions;

[0009] In the aeration tank photovoltaic power generation module, a photovoltaic power generation unit is installed on the aeration tank, photovoltaic power generation or grid off-peak power is used to compress carbon dioxide and store it in a high-pressure gas storage tank;

[0010] The heat storage module is used to store the waste heat of the gas turbine, and releases the heat to heat carbon dioxide during peak power consumption, thereby increasing power generation; the heat storage module includes: a cold tank, a hot tank, a cold heat storage fluid and a waste heat flue gas heat exchanger; the heat storage module is arranged behind the biogas combustion engine power generation module. The cold tank is a cold heat storage fluid storage tank, and the hot tank is a hot heat storage fluid storage tank.

[0011] Furthermore, in the energy storage unit, a first carbon dioxide and cooling water heat exchanger is provided between the high-pressure compressor and the low-pressure compressor, so that the heat exchanged between the circulating cooling water and the compressed carbon dioxide in the first carbon dioxide and cooling water heat exchanger is used to provide temperature conditions for the anaerobic digestion of sludge to produce biogas;

[0012] A second carbon dioxide and cooling water heat exchanger is provided between the high-pressure compressor and the high-pressure carbon dioxide storage tank, so that the carbon dioxide is stored in the high-pressure carbon dioxide storage tank.

[0013] Furthermore, in the carbon dioxide circulation power generation module, a third carbon dioxide and cooling water heat exchanger is arranged in the pipelines of the high-pressure expander and the low-pressure expander, so that the compression and expansion process in the carbon dioxide cycle is close to an ideal isothermal process, and the heat exchanged between the circulating cooling water and the compressed carbon dioxide in the third carbon dioxide and cooling water heat exchanger is used to provide temperature conditions for the anaerobic digestion of sludge to produce biogas.

[0014] Furthermore, in the carbon dioxide cycle power generation module, the high-pressure heater is a heat exchanger between waste heat flue gas and high-pressure carbon dioxide, and the low-pressure heater is a heat exchanger between waste heat flue gas and low-pressure carbon dioxide.

[0015] Furthermore, a carbon dioxide and air heat exchanger is provided between the third carbon dioxide and cooling water heat exchanger and the low-pressure carbon dioxide gas storage tank, so that the carbon dioxide after work is stored in the low-pressure carbon dioxide gas storage tank.

[0016] Furthermore, the waste heat flue gas outlet pipeline of the biogas combustion engine is divided into a first flue gas stop valve and a second flue gas stop valve, which are used to control the heat storage process and heat the carbon dioxide respectively.

[0017] Furthermore, in the thermal storage module, a first carbon dioxide shutoff valve is installed at the inlet pipe of the high-pressure carbon dioxide storage tank, a second carbon dioxide shutoff valve is installed at the inlet pipe of the low-pressure carbon dioxide storage tank, a first carbon dioxide flow control valve is installed at the outlet pipe of the high-pressure carbon dioxide storage tank, and a second carbon dioxide flow control valve is installed at the outlet pipe of the low-pressure carbon dioxide storage tank. The flow control valve is regulated according to the waste heat flue gas temperature and flow of the biogas combustion engine, thereby dynamically adjusting the carbon dioxide.

[0018] Furthermore, a first thermal storage fluid flow control valve is installed at the outlet of the cold tank, and the first thermal storage fluid flow control valve is controlled according to the waste heat temperature and flow of the biogas engine, thereby adjusting the outlet flow of the thermal storage fluid in the cold tank;

[0019] A second thermal storage fluid flow control valve is installed at the outlet of the hot tank, and the second thermal storage fluid flow control valve is controlled according to the carbon dioxide flow rate, thereby controlling the outlet flow rate of the thermal storage fluid at the hot tank outlet.

[0020] Furthermore, a flue gas flow control valve is installed at the flue gas inlet of the low-pressure heater, and the flue gas flow control valve is regulated according to the temperature and flow of the waste heat flue gas of the biogas combustion engine, thereby dynamically adjusting the flue gas flow.

[0021] Furthermore, a second heat storage fluid stop valve is provided between the cold tank, the heat storage fluid and the carbon dioxide heat exchanger, and a first heat storage fluid stop valve is provided between the cold heat storage fluid and the waste heat flue gas heat exchanger and the hot tank.

[0022] The flow control method of the present invention:

[0023] Dynamic regulation: According to the flue gas flow and temperature of the biogas burner, the carbon dioxide flow and flue gas flow are adjusted to ensure that the carbon dioxide outlet temperature in the high / low pressure heater reaches the set value, thereby maintaining the cycle power generation efficiency.

[0024] Heat storage and release stage control: In the heat storage stage, the flow rate of the heat storage fluid at the cold tank outlet is adjusted to maintain the heat storage at an optimal level; in the heat release stage, the flow rate at the hot tank outlet is controlled according to the set temperature of carbon dioxide.

[0025] The operation process of the present invention:

[0026] When electricity consumption is low: start the low-pressure gas storage tank outlet and the compressor to compress and store the carbon dioxide; at the same time, store the waste heat of the biogas engine in the hot tank through heat exchange.

[0027] During peak electricity consumption: stop the compression and heat storage process, open the high-pressure gas storage tank, hot tank outlet and high / low pressure flue gas inlet valves, heat the heat storage fluid and carbon dioxide gas, and send them to the high / low pressure expander for power generation. After power generation, the carbon dioxide gas is cooled by heat exchange and stored in the low-pressure gas storage tank.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) The system of the present invention not only optimizes the energy utilization in the sewage treatment plant, but also effectively reduces the dependence on fossil fuels, and has high environmental benefits and economic value. By integrating multiple power generation and energy storage technologies into one system, an efficient and environmentally friendly power generation solution is provided. The system effectively combines biogas combustion engines, compressed carbon dioxide cycle power generation, aeration tank photovoltaic power generation and heat storage system to achieve efficient energy utilization and dynamic peak regulation.

[0030] (2) Comprehensive utilization of resources: The biogas from the sewage treatment plant is used to generate electricity, and combined with the aeration tank photovoltaic power generation system and carbon dioxide circulation power generation technology, the energy utilization efficiency and power generation capacity are improved.

[0031] (3) Dynamic peak-shaving and energy storage: Carbon dioxide is compressed and stored through photovoltaic power generation or off-peak power of the grid, and the stored energy is released to generate electricity during peak power consumption, thus achieving dynamic peak-shaving and effective energy storage.

[0032] (4) Waste heat utilization: The waste heat from the gas turbine and high / low pressure heaters is used to dry the waste sludge, maximizing the utilization of heat and improving the overall energy efficiency of the system.

[0033] (5) Improve power generation efficiency: By precisely adjusting the carbon dioxide flow rate, flue gas flow rate, and the operation of the heat storage system, the system can maintain optimal power generation efficiency under different load conditions.

[0034] (6) Reduce system power consumption: The inlet temperature of the low-pressure gas storage tank is reduced through the radiator, thereby reducing the power consumption of the compressor and improving the cycle power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1Schematic diagram of a combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle.

[0036] Figure numerals: 1-low-pressure compressor, 2-first carbon dioxide and cooling water heat exchanger, 3-high-pressure compressor, 4-second carbon dioxide and cooling water heat exchanger, 5-first carbon dioxide shut-off valve, 6-high-pressure carbon dioxide gas storage tank, 7-first carbon dioxide flow control valve, 8-carbon dioxide and carbon dioxide heat exchanger, 9-heat storage fluid and carbon dioxide heat exchanger, 10-waste heat flue gas and high-pressure carbon dioxide heat exchanger, 11-high-pressure expander, 12-waste heat flue gas and low-pressure carbon dioxide heat exchanger, 13-low-pressure expander, 14-third carbon dioxide and cooling Water heat exchanger, 15-carbon dioxide and air heat exchanger, 16-second carbon dioxide stop valve, 17-low-pressure carbon dioxide storage tank, 18-second carbon dioxide flow control valve, 19-flue gas flow control valve, 20-cold thermal storage fluid storage tank, 21-first thermal storage fluid flow control valve, 22-cold thermal storage fluid and waste heat flue gas heat exchanger, 23-first thermal storage fluid stop valve, 24-hot thermal storage fluid storage tank, 25-second thermal storage fluid flow control valve, 26-second thermal storage fluid stop valve, 27-first flue gas stop valve, 28-second flue gas stop valve. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms and other features not clearly described in this technical solution are all considered to be common technical features disclosed in the prior art.

[0038] Example 1

[0039] This embodiment provides a combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle. Figure 1 As shown, it includes: biogas engine power generation module, aeration tank photovoltaic power generation module, carbon dioxide cycle power generation module, and heat storage module;

[0040] The biogas engine power generation module uses the biogas generated by the fermentation of sludge in the sewage treatment plant as fuel to drive the biogas engine to generate electricity, thereby making full use of the biogas resources generated in the sewage treatment plant.

[0041] The carbon dioxide cycle power generation module is based on the ideal Ericsson cycle principle and realizes power generation through isothermal compression and expansion, isobaric heat absorption and heat release processes; when electricity consumption is low, carbon dioxide is compressed and stored through photovoltaic power generation or grid low-peak electricity, and the waste heat of the gas turbine and the heat storage module are used to heat the carbon dioxide and enter the expander to generate electricity; the carbon dioxide cycle power generation module includes: an energy storage unit, a high-pressure expander 11, a low-pressure expander 13, a high-pressure heater, a low-pressure heater, and a generator; the high-pressure expander 11, the low-pressure expander 13, and the generator are connected in sequence; the energy storage unit includes: a high-pressure compressor 3, a low-pressure compressor 13, and a low-pressure compressor 14; the high-pressure compressor 14, the low-pressure compressor 14, and the low-pressure compressor 14 are connected in sequence ... A compressor 1, a high-pressure carbon dioxide gas storage tank 6, and a low-pressure carbon dioxide gas storage tank 17; the pipelines at the flue gas outlets of the high-pressure heater and the low-pressure heater are connected to the sludge drying tank, so that the waste heat flue gas that has undergone heat exchange with carbon dioxide in the heater provides corresponding heat for the sludge to be dried to meet the drying temperature conditions; a carbon dioxide and carbon dioxide heat exchanger 8, and a heat storage fluid and carbon dioxide heat exchanger 9 are provided between the high-pressure heater and the energy storage unit; the pipeline at the outlet of the carbon dioxide and carbon dioxide heat exchanger 8 is connected in series with the heat exchanger in the sludge anaerobic digestion tank, and the carbon dioxide in the pipeline provides corresponding heat for the sludge to be heated to meet the anaerobic digestion conditions;

[0042] In the aeration tank photovoltaic power generation module, a photovoltaic power generation unit is installed on the aeration tank, photovoltaic power generation or grid off-peak power is used to compress carbon dioxide and store it in a high-pressure gas storage tank;

[0043] The heat storage module is used to store the waste heat of the gas turbine, and releases the heat to heat carbon dioxide during peak power consumption, thereby increasing power generation; the heat storage module includes: a cold tank, a hot tank, a cold heat storage fluid and a waste heat flue gas heat exchanger 22; the heat storage module is arranged behind the biogas combustion engine power generation module. The cold tank is a cold heat storage fluid storage tank 20, and the hot tank is a hot heat storage fluid storage tank 24.

[0044] In a specific embodiment, in the energy storage unit, a first carbon dioxide and cooling water heat exchanger 2 is provided between the high-pressure compressor 3 and the low-pressure compressor 1, so that the heat exchanged between the circulating cooling water and the compressed carbon dioxide in the first carbon dioxide and cooling water heat exchanger 2 is used to provide temperature conditions for the anaerobic digestion of sludge to produce biogas;

[0045] A second carbon dioxide and cooling water heat exchanger 4 is provided between the high-pressure compressor 3 and the high-pressure carbon dioxide storage tank 6 , so that the carbon dioxide is stored in the high-pressure carbon dioxide storage tank 6 .

[0046] In a specific embodiment, in the carbon dioxide circulation power generation module, a third carbon dioxide and cooling water heat exchanger 14 is arranged in the pipelines of the high-pressure expander 11 and the low-pressure expander 13, so that the compression and expansion process in the carbon dioxide cycle is close to an ideal isothermal process, and the heat exchanged between the circulating cooling water and the compressed carbon dioxide in the third carbon dioxide and cooling water heat exchanger 14 is used to provide temperature conditions for the anaerobic digestion of sludge to produce biogas.

[0047] In a specific embodiment, in the carbon dioxide cycle power generation module, the high-pressure heater is a waste heat flue gas and high-pressure carbon dioxide heat exchanger 10, and the low-pressure heater is a waste heat flue gas and low-pressure carbon dioxide heat exchanger 12.

[0048] In a specific implementation, a carbon dioxide and air heat exchanger 15 is provided between the third carbon dioxide and cooling water heat exchanger 14 and the low-pressure carbon dioxide gas storage tank 17 , so that the carbon dioxide after work is stored in the low-pressure carbon dioxide gas storage tank 17 .

[0049] In a specific implementation, the waste heat flue gas outlet pipe of the biogas combustion engine is divided into a first flue gas stop valve 27 and a second flue gas stop valve 28, which are used to control the heat storage process and heat the carbon dioxide respectively.

[0050] In a specific embodiment, in the thermal storage module, a first carbon dioxide stop valve 5 is installed at the inlet pipe of the high-pressure carbon dioxide storage tank 6, a second carbon dioxide stop valve 16 is installed at the inlet pipe of the low-pressure carbon dioxide storage tank 17, a first carbon dioxide flow control valve 7 is installed at the outlet pipe of the high-pressure carbon dioxide storage tank 6, and a second carbon dioxide flow control valve 18 is installed at the outlet pipe of the low-pressure carbon dioxide storage tank 17. The flow control valve is regulated according to the waste heat flue gas temperature and flow of the biogas combustion engine, thereby dynamically adjusting the carbon dioxide.

[0051] In a specific embodiment, a first thermal storage fluid flow control valve 21 is installed at the outlet of the cold tank, and the first thermal storage fluid flow control valve 21 is controlled according to the waste heat temperature and flow of the biogas engine, thereby adjusting the outlet flow of the thermal storage fluid in the cold tank;

[0052] A second thermal storage fluid flow control valve 25 is installed at the outlet of the hot tank. The second thermal storage fluid flow control valve 25 is controlled according to the carbon dioxide flow rate, thereby controlling the outlet flow rate of the thermal storage fluid at the outlet of the hot tank.

[0053] In a specific implementation, a flue gas flow control valve 19 is installed at the flue gas inlet of the low-pressure heater, and the flue gas flow control valve 19 is regulated according to the temperature and flow of the waste heat flue gas of the biogas combustion engine, thereby dynamically adjusting the flue gas flow.

[0054] In a specific implementation, a second thermal storage fluid stop valve 26 is provided between the cold tank, the thermal storage fluid and the carbon dioxide heat exchanger 9, and a first thermal storage fluid stop valve 23 is provided between the cold thermal storage fluid and the waste heat flue gas heat exchanger 22 and the hot tank.

[0055] The specific working process is as follows:

[0056] During the off-peak period of electricity consumption, the off-peak electricity in the power grid or the electricity generated by the photovoltaic device built in the aeration tank of the sewage treatment plant is consumed, and the low-temperature and low-pressure carbon dioxide in the low-pressure carbon dioxide storage tank 17 is controlled by the second carbon dioxide flow control valve 18 to flow into the low-pressure compressor 1 for compression, and after rising to a certain pressure, it enters the first carbon dioxide and cooling water heat exchanger 2 for cooling. The inlet and outlet circulating cooling water in the first carbon dioxide and cooling water heat exchanger 2 surrounds the sludge anaerobic consumption tank in the sewage treatment plant through pipelines to provide the temperature conditions for the sludge in the tank to produce biogas fermentation, and the first After the carbon dioxide is heat exchanged with the cooling water in the carbon dioxide and cooling water heat exchanger 2, it enters the high-pressure compressor 3 and is compressed to a specified pressure. The carbon dioxide then enters the second carbon dioxide and cooling water heat exchanger 4 to exchange heat with the cooling water. The inlet and outlet circulating cooling water in the second carbon dioxide and cooling water heat exchanger 4 surrounds the anaerobic consumption pool of the sludge in the sewage treatment plant through a pipeline to provide the temperature conditions for the sludge in the pool to produce biogas fermentation. The carbon dioxide after the heat exchange with the cooling water in the second carbon dioxide and cooling water heat exchanger 4 is stored in the high-pressure carbon dioxide gas storage tank 6 through the first carbon dioxide stop valve 5. At the same time, the second flue gas stop valve 28 is in a closed state, the first flue gas stop valve 27 is opened, and the waste heat flue gas of the biogas combustion engine enters the cold heat storage fluid and waste heat flue gas heat exchanger 22, and performs heat exchange with the heat storage fluid in the cold heat storage fluid storage tank 20 through the first heat storage fluid flow control valve 21. The heat storage fluid after absorbing the waste heat of the flue gas flows through the first heat storage fluid stop valve 23 and enters the hot heat storage fluid storage tank 24.

[0057] During the peak period of electricity consumption, the high-pressure carbon dioxide storage tank 6 will dynamically monitor and control the carbon dioxide outlet flow of the first carbon dioxide flow control valve 7 according to the waste heat flue gas flow and temperature of the biogas combustion engine. After the carbon dioxide and carbon dioxide heat exchanger 8 exchange heat with the carbon dioxide after work, it enters the heat storage fluid and carbon dioxide heat exchanger 9 to exchange heat with the heat storage fluid. At this time, the outlet flow of the second heat storage fluid flow control valve 25 will be controlled according to the preheater carbon dioxide outlet set temperature. The heat storage fluid after heat exchange will flow through the second heat storage fluid stop valve 26 and return to the cold heat storage fluid storage tank 20 for the next heat storage process. After that, the system will control the outlet flue gas flow of the flue gas flow valve 19 according to the set temperature of carbon dioxide, in order to ensure that the carbon dioxide outlet temperature of the waste heat flue gas and the high-pressure carbon dioxide heat exchanger 10, and the waste heat flue gas and the low-pressure carbon dioxide heat exchanger 12 are consistent. The carbon dioxide coming out of the heat storage fluid and carbon dioxide heat exchanger 9 will enter the waste heat flue gas and high pressure carbon dioxide heat exchanger 10, so that the carbon dioxide temperature rises to a specified temperature and then performs work in the high pressure expander 11. At the same time, the carbon dioxide after the high pressure expander 11 performs heat exchange with another part of the high temperature waste heat flue gas from the biogas engine in the waste heat flue gas and low pressure carbon dioxide heat exchanger 12, so that the carbon dioxide temperature rises to a specified temperature again, enters the low pressure expander 13 to perform work, and drives the generator to generate electricity at the same time as the high pressure expander 11. The waste heat flue gas in the waste heat flue gas and high pressure carbon dioxide heat exchanger 10 and the waste heat flue gas and low pressure carbon dioxide heat exchanger 12 are uniformly recovered after heat exchange with carbon dioxide, and transmitted through pipelines, and the waste heat is used for sludge drying in sewage treatment plants. The carbon dioxide that has done work in the low-pressure expander 13 enters the carbon dioxide and carbon dioxide heat exchanger 8 and transfers heat to the cold-end carbon dioxide before entering the heat storage fluid and carbon dioxide heat exchanger 9, so that the cold-end carbon dioxide is heated. The cooled medium-temperature carbon dioxide transfers heat to the sewage treatment plant sludge drying through the pipeline. The carbon dioxide after this process enters the third carbon dioxide and cooling water heat exchanger 14 to exchange heat with cooling water. The inlet and outlet circulating cooling water in the third carbon dioxide and cooling water heat exchanger 14 surrounds the sludge anaerobic consumption pool in the sewage treatment plant through the pipeline to provide the temperature conditions for the sludge in the pool to produce biogas fermentation. After the heat exchange of the third carbon dioxide and cooling water heat exchanger 14, the outlet low-pressure carbon dioxide enters the carbon dioxide and air heat exchanger 15 to cool to the ambient temperature, and then flows through the second carbon dioxide stop valve 16 and is sent to the low-pressure carbon dioxide gas storage tank 17. So far, the photovoltaic power generation in the thermal power storage peak-shaving aeration pool of the sewage treatment plant and the power generation process of biogas and carbon dioxide circulation combined by anaerobic consumption of sludge are realized.

[0058] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0059] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle, characterized in that: include: Biogas engine power generation module, aeration tank photovoltaic power generation module, carbon dioxide cycle power generation module, heat storage module; The biogas engine power generation module uses the biogas generated by the fermentation of sludge in the sewage treatment plant as fuel to drive the biogas engine to generate electricity; The carbon dioxide cycle power generation module is based on the ideal Ericsson cycle principle and realizes power generation through isothermal compression and expansion, isobaric heat absorption and heat release processes. When electricity consumption is low, carbon dioxide is compressed and stored through photovoltaic power generation or grid low-peak electricity, and the waste heat of the gas turbine and the heat storage module are used to heat the carbon dioxide and enter the expander to generate electricity. The carbon dioxide cycle power generation module comprises: an energy storage unit, a high-pressure expander (11), a low-pressure expander (13), a high-pressure heater, a low-pressure heater, and a generator; the high-pressure expander (11), the low-pressure expander (13), and the generator are connected in sequence; the energy storage unit comprises: a high-pressure compressor (3), a low-pressure compressor (1), a high-pressure carbon dioxide gas storage tank (6), and a low-pressure carbon dioxide gas storage tank (17); pipelines at the flue gas outlets of the high-pressure heater and the low-pressure heater are connected to the sludge drying tank, so that the waste heat flue gas in the heater that undergoes heat exchange with carbon dioxide provides corresponding heat for the sludge to be dried to meet the drying temperature conditions; a carbon dioxide and carbon dioxide heat exchanger (8) and a heat storage fluid and carbon dioxide heat exchanger (9) are provided between the high-pressure heater and the energy storage unit; the pipeline at the outlet of the carbon dioxide and carbon dioxide heat exchanger (8) is connected in series with the heat exchanger in the sludge anaerobic digestion tank, and the carbon dioxide in the pipeline provides corresponding heat for the sludge to be heated to meet the anaerobic digestion conditions; In the aeration tank photovoltaic power generation module, a photovoltaic power generation unit is installed on the aeration tank, photovoltaic power generation or grid off-peak power is used to compress carbon dioxide and store it in a high-pressure gas storage tank; The heat storage module is used to store waste heat from the gas turbine and release the heat to heat carbon dioxide during peak electricity consumption, thereby increasing power generation; the heat storage module comprises: a cold tank, a hot tank, a cold heat storage fluid and a waste heat flue gas heat exchanger (22); the heat storage module is arranged behind the biogas combustion engine power generation module.

2. According to claim 1, a sewage treatment plant combined cycle power generation system based on the ideal Ericsson cycle principle is characterized in that: In the energy storage unit, a first carbon dioxide and cooling water heat exchanger (2) is provided between the high-pressure compressor (3) and the low-pressure compressor (1), so that the heat exchanged between the circulating cooling water and the compressed carbon dioxide in the first carbon dioxide and cooling water heat exchanger (2) is used to provide temperature conditions for the anaerobic digestion of sludge to produce biogas; A second carbon dioxide and cooling water heat exchanger (4) is provided between the high-pressure compressor (3) and the high-pressure carbon dioxide storage tank (6), so that the carbon dioxide is stored in the high-pressure carbon dioxide storage tank (6).

3. The combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle according to claim 1 is characterized in that: In the carbon dioxide circulation power generation module, a third carbon dioxide and cooling water heat exchanger (14) is arranged in the pipelines of the high-pressure expander (11) and the low-pressure expander (13), so that the compression and expansion process in the carbon dioxide circulation is close to an ideal isothermal process, and the heat exchanged between the circulating cooling water and the compressed carbon dioxide in the third carbon dioxide and cooling water heat exchanger (14) is used to provide temperature conditions for anaerobic digestion of sludge to produce biogas.

4. The combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle according to claim 1 is characterized in that: In the carbon dioxide cycle power generation module, the high-pressure heater is a waste heat flue gas and high-pressure carbon dioxide heat exchanger (10), and the low-pressure heater is a waste heat flue gas and low-pressure carbon dioxide heat exchanger (12).

5. The sewage treatment plant combined cycle power generation system based on the ideal Ericsson cycle principle according to claim 3 is characterized in that: A carbon dioxide and air heat exchanger (15) is provided between the third carbon dioxide and cooling water heat exchanger (14) and the low-pressure carbon dioxide gas storage tank (17), so that the carbon dioxide after work is stored in the low-pressure carbon dioxide gas storage tank (17).

6. The sewage treatment plant combined cycle power generation system based on the ideal Ericsson cycle principle according to claim 1 is characterized in that: The waste heat flue gas outlet pipeline of the biogas combustion engine is divided into a first flue gas stop valve (27) and a second flue gas stop valve (28), which are used to control the heat storage process and heat the carbon dioxide respectively.

7. The combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle according to claim 1 is characterized in that: In the thermal storage module, a first carbon dioxide stop valve (5) is installed at the inlet pipeline of the high-pressure carbon dioxide storage tank (6), a second carbon dioxide stop valve (16) is installed at the inlet pipeline of the low-pressure carbon dioxide storage tank (17), a first carbon dioxide flow control valve (7) is installed at the outlet pipeline of the high-pressure carbon dioxide storage tank (6), and a second carbon dioxide flow control valve (18) is installed at the outlet pipeline of the low-pressure carbon dioxide storage tank (17).

8. The combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle according to claim 1 is characterized in that: A first heat storage fluid flow control valve (21) is installed at the outlet of the cold tank, and the first heat storage fluid flow control valve (21) is controlled according to the waste heat temperature and flow of the biogas engine, thereby adjusting the outlet flow of the heat storage fluid in the cold tank; A second heat storage fluid flow control valve (25) is installed at the outlet of the hot tank, and the second heat storage fluid flow control valve (25) is controlled according to the carbon dioxide flow rate, thereby controlling the outlet flow rate of the heat storage fluid at the outlet of the hot tank.

9. The combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle according to claim 1, characterized in that: A flue gas flow control valve (19) is installed at the flue gas inlet of the low-pressure heater, and the flue gas flow control valve (19) is regulated according to the temperature and flow of the waste heat flue gas of the biogas combustion engine, thereby dynamically adjusting the flue gas flow.

10. A combined cycle power generation system for a sewage treatment plant based on the ideal Ericsson cycle principle according to claim 1, characterized in that: A second heat storage fluid stop valve (26) is provided between the cold tank, the heat storage fluid and the carbon dioxide heat exchanger (9), and a first heat storage fluid stop valve (23) is provided between the cold heat storage fluid and the waste heat flue gas heat exchanger (22) and the hot tank.

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