A combined heat and power generation device and method for coupling carbon dioxide power generation and geothermal energy

Abstract

The present invention discloses a heat and power cogeneration device and method for coupling carbon dioxide power generation and geothermal energy. In addition to realizing the thermoelectric conversion of new energy sources such as solar energy by utilizing supercritical carbon dioxide power generation, the quality of medium and low temperature geothermal energy is improved at the same time, and the comprehensive application of power generation and heat supply is realized. Moreover, the matching between electricity and heat can be flexibly adjusted according to actual needs, and the full comprehensive utilization of new energy sources such as solar energy, nuclear energy and geothermal energy is realized. In addition, the phase change heat transfer characteristics of the absorption heat pump can better control the temperature of supercritical carbon dioxide at the compressor inlet, and improve the stability of the supercritical carbon dioxide power generation system.

Description

Technical Field

[0001] The present invention belongs to the field of thermoelectricity, and in particular to a cogeneration device and method for coupling carbon dioxide power generation and geothermal energy. Background Art

[0002] Supercritical carbon dioxide power generation is a power generation method that uses supercritical carbon dioxide as a circulating working fluid. Compared with traditional steam generators, supercritical carbon dioxide power generation has the characteristics of good heat source matching, high flexibility, and excellent efficiency. It is suitable for medium-temperature heat sources and has broad application prospects in the fields of solar energy and nuclear power generation. Geothermal energy is a medium- and low-temperature heat source. It has been used in some heating applications in the north. Geothermal heating, as a clean heating method, will be highly competitive in the future heating market.

[0003] Supercritical carbon dioxide power generation mainly uses medium-temperature heat sources of 600-750°C, and uses supercritical carbon dioxide as a circulating working fluid to achieve the conversion process of heat and electricity. Among them, the temperature of supercritical carbon dioxide at the turbine outlet is often above 500°C. At present, this part of the heat is usually recovered by low-temperature carbon dioxide through a recuperator. Considering that the heating capacity of thermal power units will be further restricted in the future, it is necessary to explore new heating methods under the background of new energy structure. Geothermal energy, as a medium- and low-temperature heating source, has been studied and applied to a certain extent.

[0004] At present, there are the following problems in the field of supercritical carbon dioxide power generation and geothermal heating: 1. The outlet temperature of supercritical carbon dioxide power generation turbine is generally around 500℃, which has a high potential for waste heat utilization. At present, this part of heat is mostly recycled through the recuperator, and there are certain restrictions on heat utilization. 2. In terms of geothermal heating, the temperature of geothermal water directly used is relatively low, generally between 40 and 70℃, and the heating capacity is limited. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art and to provide a heat and power cogeneration device and method for coupling carbon dioxide power generation and geothermal energy.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A heat and power cogeneration device coupling carbon dioxide power generation and geothermal energy, comprising a heat absorber, a carbon dioxide turbine, a high-temperature carbon dioxide regenerator, a condenser, an evaporator, a low-temperature carbon dioxide regenerator, a carbon dioxide cooler, a geothermal well and a solution circulation unit;

[0008] The high-temperature and high-pressure carbon dioxide in the absorber absorbs heat and enters the carbon dioxide turbine to perform work. After performing work, it enters the high-temperature carbon dioxide regenerator for heat exchange. After heat exchange, a part of it enters the low-temperature carbon dioxide regenerator for continued heat exchange, and the other part enters the solution circulation unit; the carbon dioxide after heat exchange in the low-temperature carbon dioxide regenerator enters the carbon dioxide cooler, and returns to the low-temperature carbon dioxide regenerator after heat exchange with the return water of the heat network; the carbon dioxide that performs heat exchange in the solution circulation unit returns to the low-temperature carbon dioxide regenerator from the carbon dioxide cooler after heat exchange;

[0009] The water in the lithium bromide concentrated solution in the solution circulation unit absorbs heat and evaporates into water vapor, which enters the condenser for heat exchange, and then condenses into liquid water, which enters the evaporator for further heat exchange, and then evaporates into water vapor again, which enters the solution circulation unit, and the geothermal water enters the evaporator for heat release, and then is re-injected into the geothermal well;

[0010] The return water from the heat network enters the carbon dioxide cooler for heat exchange and then enters the solution circulation unit for further heat exchange. After heat exchange, it enters the condenser for heat exchange again and then is discharged as heat network supply water.

[0011] Furthermore, the solution circulation unit includes a generator, an absorber and a solution heat exchanger. The lithium bromide concentrated solution in the generator enters the solution heat exchanger for further heat exchange after heat exchange, enters the absorber for further heat exchange after heat exchange, enters the solution heat exchanger for further heat exchange after heat exchange, and then returns to the generator.

[0012] Furthermore, a carbon dioxide compressor is provided between the low-temperature carbon dioxide regenerator and the carbon dioxide cooler.

[0013] Furthermore, a carbon dioxide heat recovery regulating valve is provided between the high-temperature carbon dioxide heat regenerator and the generator.

[0014] Furthermore, a solvent throttle valve is provided between the condenser and the evaporator.

[0015] Furthermore, a solution expansion valve is provided between the solution heat exchanger and the absorber.

[0016] Furthermore, a solution pump is provided between the absorber and the solution heat exchanger.

[0017] Furthermore, the carbon dioxide cooler is connected to a heat network return water system.

[0018] Furthermore, the condenser is connected to a heat network water supply system.

[0019] The cogeneration method of the device for generating electricity with carbon dioxide and coupling geothermal energy comprises:

[0020] Power generation method: The high-temperature and high-pressure carbon dioxide from the high-temperature carbon dioxide regenerator absorbs heat and enters the carbon dioxide turbine to do work, and then enters the high-temperature carbon dioxide regenerator to release heat. The carbon dioxide after heat release is divided into two paths at the outlet of the carbon dioxide regenerator, one path enters the generator in the absorption heat pump; the other path enters the low-temperature carbon dioxide regenerator, exchanges heat with the low-temperature carbon dioxide from the carbon dioxide compressor, and then enters the carbon dioxide cooler, where it is cooled to below 35°C through the heat network return water, and then enters the carbon dioxide compressor for compression to start a new cycle;

[0021] Heating method: The dilute lithium bromide solution in the generator absorbs the heat in the carbon dioxide, causing the water in the dilute solution to absorb heat and evaporate. The evaporated water vapor enters the condenser, and the carbon dioxide with reduced temperature enters the carbon dioxide cooler; the water vapor in the condenser exchanges heat with the water supplied by the heat network, condenses itself into liquid water, and enters the evaporator after being reduced in pressure by the solvent throttle valve. In the evaporator, it absorbs the heat from the geothermal water in the geothermal well and evaporates again, allowing the water vapor to enter the absorber from the evaporator, and the temperature of the lithium bromide concentrated solution in the generator is increased, and then it first enters the solution heat exchange The lithium bromide concentrated solution after heat exchange is throttled and depressurized by the solution expansion valve, and then enters the absorber to absorb water vapor from the evaporator to release heat. Then, it is pressurized by the solution pump and enters the solution heat exchanger to recover the heat of the lithium bromide concentrated solution and then enters the generator to complete the solution circulation. The heat network return water at about 20°C first enters the carbon dioxide cooler to absorb the waste heat of carbon dioxide, and then enters the absorber to absorb the heat in the solution absorption process. Finally, it enters the condenser to absorb the heat of water vapor condensation, so that the heat network return water outlet temperature in the condenser meets the hot water supply requirement.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a combined heat and power generation device and method for coupling carbon dioxide power generation and geothermal energy, which utilizes the high-temperature heat in the carbon dioxide heat recovery process to increase the low-temperature heat of geothermal water, thereby improving the energy utilization grade of geothermal water. The heat network return water successively absorbs the waste heat of carbon dioxide, the heat of the absorber, and the heat of the condenser, thereby realizing the comprehensive utilization of new energy sources such as solar energy, nuclear energy, and geothermal energy for power generation and heat supply. The joint scheduling of multiple new energy sources in the future energy structure is realized, and the flexibility of new energy utilization is improved. This solution realizes the comprehensive utilization and joint scheduling of high-quality solar energy, nuclear energy, and low-quality geothermal energy for power generation and heat supply, making the utilization of high-temperature heat and low-temperature heat more comprehensive and efficient, avoiding the waste heat waste problem of carbon dioxide power generation itself, and solving the problem of low temperature grade of geothermal energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A diagram of a combined heat and power device for coupling carbon dioxide power generation and geothermal energy according to the present invention;

[0026] Among them: 1-carbon dioxide heat recovery regulating valve, 2-heat absorber, 3-carbon dioxide turbine, 4-high temperature carbon dioxide heat recovery device, 5-carbon dioxide compressor, 6-generator, 7-condenser, 8-evaporator, 9-absorber, 10-solution heat exchanger, 11-solution expansion valve, 12-solution pump, 13-solvent throttle valve, 14-low temperature carbon dioxide heat recovery device, 15-carbon dioxide cooler, 16-geothermal well. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0031] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0034] See also Figure 1 The present invention provides a heat and power cogeneration device coupling carbon dioxide power generation and geothermal energy, comprising a carbon dioxide heat recovery regulating valve 1, a heat absorber 2, a carbon dioxide turbine 3, a high-temperature carbon dioxide heat regenerator 4, a carbon dioxide compressor 5, a generator 6, a condenser 7, an evaporator 8, an absorber 9, a solution heat exchanger 10, a solution expansion valve 11, a solution pump 12, a solvent throttle valve low temperature 13, a carbon dioxide heat regenerator 14, a carbon dioxide cooler 15 and a geothermal well 16.

[0035] The low temperature side outlet of the high temperature carbon dioxide regenerator 4 is connected to the inlet of the heat absorber 2, the outlet of the heat absorber 2 is connected to the inlet of the carbon dioxide turbine 3, the outlet of the carbon dioxide turbine 3 is connected to the high temperature side inlet of the high temperature carbon dioxide regenerator 4, the high temperature side outlet of the high temperature carbon dioxide regenerator 4 is connected to the high temperature side inlet of the low temperature carbon dioxide regenerator 14, the high temperature side outlet of the low temperature carbon dioxide regenerator 14 is connected to the first high temperature side inlet of the carbon dioxide cooler 15, the high temperature side outlet of the carbon dioxide cooler 15 is connected to the inlet of the carbon dioxide compressor 5, the outlet of the carbon dioxide compressor 5 is connected to the low temperature side inlet of the low temperature carbon dioxide regenerator 14, and the low temperature side outlet of the low temperature carbon dioxide regenerator 14 is connected to the low temperature side inlet of the high temperature carbon dioxide regenerator 4;

[0036] The high temperature side outlet of the high temperature carbon dioxide regenerator 4 is connected to the high temperature side inlet of the generator 6 through the carbon dioxide regulating valve 1, the first high temperature side outlet of the generator 6 is connected to the high temperature side inlet of the condenser 7, the high temperature side outlet of the condenser 7 is connected to the low temperature side inlet of the evaporator 8 through the solvent throttle valve 13, the low temperature side outlet of the evaporator 8 is connected to the first low temperature side inlet of the absorber 9, the high temperature side outlet of the absorber 9 is connected to the low temperature side inlet of the solution heat exchanger 10 through the solution pump 12, the low temperature side outlet of the solution heat exchanger 10 is connected to the low temperature side inlet of the generator 6, and the low temperature side outlet of the generator 6 is connected to the high temperature side inlet of the solution heat exchanger 10. The high temperature side outlet of the solution heat exchanger 10 is connected to the high temperature side inlet of the absorber 9 through the solution expansion valve 11, the second high temperature side outlet of the generator 6 is connected to the second high temperature side inlet of the carbon dioxide cooler 15, the low temperature side outlet of the carbon dioxide cooler 15 is connected to the second low temperature side inlet of the absorber 9, the high temperature side outlet of the evaporator 8 is connected to the inlet of the geothermal well 16, the outlet of the geothermal well 16 is connected to the high temperature side inlet of the evaporator 8, the low temperature side outlet of the absorber 9 is connected to the low temperature side inlet of the condenser 7, the low temperature side inlet of the carbon dioxide cooler 15 is connected to the heat network return water system, and the low temperature side outlet of the condenser 7 is connected to the heat network water supply system.

[0037] The power generation function of the present invention is mainly realized by the carbon dioxide power generation system. In the carbon dioxide power generation system loop, the high-temperature and high-pressure carbon dioxide from the high-temperature carbon dioxide regenerator 4 absorbs heat from new energy sources such as solar energy and nuclear energy in the absorber 2, and then enters the carbon dioxide turbine 3 to perform work, completing the heat-to-electricity conversion process. After completing the work, the carbon dioxide still has high-temperature heat above 400°C. The high-temperature carbon dioxide first enters the high-temperature carbon dioxide regenerator 4 to release part of the heat to the low-temperature carbon dioxide from the low-temperature carbon dioxide regenerator 14. The carbon dioxide after heat release is divided into two paths at the outlet of the high-temperature carbon dioxide regenerator 4. One path enters the generator 6 in the absorption heat pump, with the purpose of introducing part of the higher temperature carbon dioxide in the regeneration process into the generator 6 in the absorption heat pump. The temperature of this part of carbon dioxide is above 150°C. A carbon dioxide regeneration regulating valve 1 is provided on the connecting loop, which is mainly used to control the carbon dioxide branch flow at the outlet of the high-temperature carbon dioxide regenerator 4 and adjust the energy distribution for power generation and heating; the other path enters the low-temperature carbon dioxide regenerator 14, exchanges heat with the low-temperature carbon dioxide from the carbon dioxide compressor 5, and the high-temperature side outlet of the low-temperature carbon dioxide regenerator 14 enters the carbon dioxide cooler 15, is cooled to below 35°C by the return water of the heat network, and then enters the carbon dioxide compressor 5 to be compressed, starting a new cycle.

[0038] The heating function of the present invention is mainly realized by recycling the heat of high-temperature carbon dioxide and low-temperature geothermal water through an absorption heat pump. In the generator 6, the driving heat source of the generator is the high-temperature carbon dioxide from the high-temperature carbon dioxide regenerator 4. The dilute lithium bromide solution absorbs the heat in the carbon dioxide, and the water in the dilute solution absorbs the heat and evaporates. The concentration of the original solution in the generator 6 increases, and the evaporated water vapor enters the condenser 7. The temperature of carbon dioxide is reduced from more than 150°C to less than 110°C. The carbon dioxide after the temperature is reduced and the carbon dioxide with a lower temperature at the high-temperature side outlet of the low-temperature carbon dioxide regenerator 14 enter the carbon dioxide cooler 15 together. The water vapor in the condenser 7 exchanges heat with the water supply of the heat network, condenses itself into liquid water, and enters the evaporator 8 after the pressure is reduced by the solvent throttle valve 13. In the evaporator 8, it absorbs the heat of the geothermal water in the geothermal well 16 and evaporates again. The water vapor enters the absorber 9 from the evaporator 8, and the geothermal water releases heat in the evaporator 8 and is then re-injected into the geothermal well 16. The temperature of the lithium bromide concentrated solution in the generator 6 is increased, and then it first enters the solution heat exchanger 10 to exchange heat with the lithium bromide dilute solution from the absorber 9. After the heat exchange, the lithium bromide concentrated solution passes through the solution expansion valve 11 for throttling and pressure reduction, enters the absorber 9 to absorb the water vapor from the evaporator 8, releases heat, and then enters the solution heat exchanger after being pressurized by the solution pump 12. After recovering the heat of the lithium bromide concentrated solution, it enters the generator 6 to complete the circulation of the solution. The heat network return water at about 20°C first enters the carbon dioxide cooler 15 to absorb the waste heat of carbon dioxide, and then enters the absorber 9 to absorb the heat in the solution absorption process; finally, it enters the condenser 7 to absorb the heat of the condensation of water vapor. The outlet temperature of the heat network return water in the condenser 7 meets the requirements for hot water supply, thereby realizing the heating function of the device of the present invention.

[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A combined heat and power generation device combining carbon dioxide power generation and geothermal energy, characterized in that: It includes a heat absorber (2), a carbon dioxide turbine (3), a high-temperature carbon dioxide regenerator (4), a condenser (7), an evaporator (8), a low-temperature carbon dioxide regenerator (14), a carbon dioxide cooler (15), a geothermal well (16), and a solution circulation unit; After absorbing heat, the high-temperature and high-pressure carbon dioxide in the absorber (2) enters the carbon dioxide turbine (3) to perform work, and after performing work, enters the high-temperature carbon dioxide regenerator (4) for heat exchange. After heat exchange, a portion of the carbon dioxide enters the low-temperature carbon dioxide regenerator (14) for further heat exchange, and the other portion enters the solution circulation unit; the carbon dioxide after heat exchange in the low-temperature carbon dioxide regenerator (14) enters the carbon dioxide cooler (15), and after heat exchange with the return water of the heat network, returns to the low-temperature carbon dioxide regenerator (14); the carbon dioxide that has undergone heat exchange in the solution circulation unit returns to the low-temperature carbon dioxide regenerator (14) from the carbon dioxide cooler (15); a carbon dioxide compressor (5) is provided between the low-temperature carbon dioxide regenerator (14) and the carbon dioxide cooler (15); a carbon dioxide regenerator regulating valve (1) is provided between the high-temperature carbon dioxide regenerator (4) and the generator (6); The water in the lithium bromide concentrated solution in the solution circulation unit absorbs heat and then evaporates into water vapor, which enters the condenser (7) for heat exchange. After the heat exchange, the water condenses into liquid water and enters the evaporator (8) for further heat exchange. After the heat exchange, the water evaporates into water vapor again and enters the solution circulation unit. The geothermal water enters the evaporator (8) for heat release and then is re-injected into the geothermal well (16). A solvent throttle valve (13) is provided between the condenser (7) and the evaporator (8). The return water from the heat network enters the carbon dioxide cooler (15) for heat exchange and then enters the solution circulation unit for further heat exchange. After the heat exchange, it enters the condenser (7) for further heat exchange and then is discharged as the heat network supply water. The solution circulation unit comprises a generator (6), an absorber (9) and a solution heat exchanger (10); the lithium bromide concentrated solution in the generator (6) enters the solution heat exchanger (10) for further heat exchange after heat exchange, enters the absorber (9) for further heat exchange after heat exchange, enters the solution heat exchanger (10) for further heat exchange after heat exchange, and then returns to the generator (6); a solution expansion valve (11) is provided between the solution heat exchanger (10) and the absorber (9); and a solution pump (12) is provided between the absorber (9) and the solution heat exchanger (10).

2. A combined heat and power generation device combining carbon dioxide power generation and geothermal energy according to claim 1, characterized in that: The carbon dioxide cooler (15) is connected to the heat network return water system.

3. A combined heat and power generation device combining carbon dioxide power generation and geothermal energy according to claim 1, characterized in that: The condenser (7) is connected to the heating network water supply system.

4. A combined heat and power generation method of carbon dioxide power generation and geothermal energy coupling according to any one of claims 1 to 3, characterized in that: include: Power generation method: high-temperature and high-pressure carbon dioxide from a high-temperature carbon dioxide regenerator (4) absorbs heat and enters a carbon dioxide turbine (3) to perform work, then enters a high-temperature carbon dioxide regenerator (4) to release heat, and the carbon dioxide after releasing heat is divided into two paths at the outlet of the high-temperature carbon dioxide regenerator (4), one path enters a generator (6) in an absorption heat pump; the other path enters a low-temperature carbon dioxide regenerator (14), exchanges heat with the low-temperature carbon dioxide from a carbon dioxide compressor (5), and then enters a carbon dioxide cooler (15), where it is cooled to below 35°C by heat network return water, and then enters a carbon dioxide compressor (5) for compression, thereby starting a new cycle; Heating method: the lithium bromide dilute solution in the generator (6) absorbs heat in the carbon dioxide, causing the water in the dilute solution to absorb heat and evaporate, and the evaporated water vapor enters the condenser (7), and the carbon dioxide with a lowered temperature enters the carbon dioxide cooler (15); the water vapor in the condenser (7) exchanges heat with the water supplied by the heat network, condenses itself into liquid water, and enters the evaporator (8) after the pressure is reduced by the solvent throttle valve (13). In the evaporator (8), the water vapor absorbs the heat from the geothermal water in the geothermal well (16) and evaporates again, so that the water vapor enters the absorber (9) from the evaporator (8), and the temperature of the lithium bromide concentrated solution in the generator (6) is increased, and then first enters the solution The heat exchanger (10) exchanges heat, and the lithium bromide concentrated solution after heat exchange passes through the solution expansion valve (11) for throttling and pressure reduction, and then enters the absorber (9) to absorb water vapor from the evaporator (8) to release heat, and then passes through the solution pump (12) for pressurization and enters the solution heat exchanger to recover the heat of the lithium bromide concentrated solution, and then enters the generator (6) to complete the solution circulation; the 20°C hot network return water first enters the carbon dioxide cooler (15) to absorb the waste heat of carbon dioxide, and then enters the absorber (9) to absorb the heat in the solution absorption process; and finally enters the condenser (7) to absorb the heat of condensation of water vapor, so that the outlet temperature of the hot network return water in the condenser (7) meets the requirements for hot water supply.

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