Wide-working-condition steam generation system based on multi-source coupling heat pump and dynamic adjusting method

Abstract

The invention discloses a wide-working-condition steam generation system based on a multi-source coupling heat pump and a dynamic adjusting method, and belongs to the technical field of industrial steam production and comprehensive utilization of energy, the wide-working-condition steam generation system comprises a heat pump circulation subsystem, and the heat pump circulation subsystem comprises an evaporator, a low-temperature heat regenerator, a compressor and a high-temperature heat regenerator which are connected in sequence; the electric heater and the combustor are connected behind an outlet of the high-temperature heat regenerator in a shunting manner; the outlets of the electric heater and the combustor are converged, then are sequentially connected with the high-pressure cooler, the first low-pressure cooler, the second low-pressure cooler and the throttling valve and are connected back to the evaporator. According to the invention, three types of energy sources, namely, chemical energy, solar energy, wind energy and other new energy power generation electric energy of oil field associated gas and low-grade heat energy of a ground source, are integrated, a ground source heat pump is used for providing a basic heat load, new energy power generation electric heating and associated gas combustion are used for raising the temperature, and steam output ends with different temperatures and pressures are configured, so that the energy efficiency is improved. And efficient gradient utilization of energy and wide-working-condition steam production are achieved.

Description

Technical Field

[0001] This invention belongs to the field of industrial steam production and comprehensive energy utilization technology, and particularly relates to a steam generation system based on a multi-source coupled heat pump with wide operating conditions and a dynamic adjustment method. Background Technology

[0002] Oilfield development generates a large amount of associated gas, which is traditionally treated by direct venting and combustion. This not only wastes energy but also produces CO2 and NO. x Pollutants such as these do not meet the goal of "carbon peaking and carbon neutrality". At the same time, oil fields and surrounding areas often have abundant new energy resources such as wind and solar energy, but their energy value has not been fully explored. Although ground source heat pump technology can stably obtain low-grade underground heat energy, its heating efficiency is low when used alone and cannot directly meet the demand for industrial high-temperature steam (usually above 300°C).

[0003] In existing industrial high-temperature steam production technologies, relying solely on fossil fuels (such as natural gas and crude oil) is costly and highly polluting. Pure electric heating is limited by grid electricity prices and stability, and a single heat pump system cannot output sufficient temperature. Although some existing technologies attempt to couple two energy sources, such as using associated gas boilers with electric heating, they have not achieved efficient synergy between new energy sources, associated gas, and heat pumps. This results in low energy utilization and poor steam production efficiency, leading to energy waste. Therefore, there is an urgent need for a coupled system that can integrate the advantages of three types of energy: associated gas from oil fields, new energy power generation, and ground source heat pumps, to achieve cascaded energy utilization and stable steam production. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high cost and pollution associated with relying solely on fossil fuels in high-temperature steam production technology, as well as low energy utilization and poor steam production efficiency due to energy coupling. This invention proposes a steam generation system and dynamic adjustment method based on a multi-source coupled heat pump with wide operating conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A wide-condition steam generation system based on a multi-source coupled heat pump includes: The heat pump cycle subsystem includes an evaporator, a low-temperature regenerator, a compressor, a high-temperature regenerator connected in sequence, and an electric heater and a burner connected in a branch line after the outlet of the high-temperature regenerator. The outlets of the electric heater and the burner merge and are sequentially connected to the high-pressure cooler, the first low-pressure cooler, the second low-pressure cooler, the throttle valve, and then back to the evaporator; The heat pump cycle subsystem also includes a water separator and a dryer connected between the second low-pressure cooler and the throttle valve; The associated gas and carbon capture subsystem includes a purifier, a booster, a fifth valve, an associated gas storage tank, a sixth valve, and a fuel preheater connected in sequence. The purifier is used to receive associated gas from the oilfield, and the outlet of the fuel preheater is connected to the burner; It also includes a carbon dioxide buffer tank and a carbon dioxide injection pump connected to the compressor outlet. The steam generation subsystem includes a water storage tank, a high-pressure water pump, a low-pressure water pump, a low-pressure steam buffer tank, and a high-pressure steam buffer tank; The high-pressure water pump sends water from the storage tank to the first low-pressure cooler for preheating, and then the water is evaporated by the high-pressure cooler to generate high-pressure steam. The low-pressure water pump sends water from the storage tank into the second low-pressure cooler to evaporate and generate low-pressure steam. The energy supply and control subsystem includes a central controller and a new energy power generation unit; the new energy power generation unit is electrically connected to a compressor, an electric heater, and a carbon dioxide injection pump; the central controller is used to dynamically adjust the system operation according to the amount of new energy generated and the associated gas flow.

[0006] As a further description of the above technical solution: The burner is configured to directly discharge the high-temperature carbon dioxide and water vapor generated by the combustion of associated gas into the heat pump circulation pipeline to participate in the circulation. Part of the working fluid at the compressor outlet is guided to a carbon dioxide buffer tank, and after being pressurized by a carbon dioxide injection pump, it is injected into depleted oil wells for storage.

[0007] As a further description of the above technical solution: The low-temperature regenerator is configured to absorb the waste heat of the working fluid before the throttling valve using the working fluid at the evaporator outlet. The high-temperature regenerator is configured to absorb the waste heat of the working fluid at the outlet of the high-pressure cooler using the working fluid at the compressor outlet.

[0008] As a further description of the above technical solution: A second valve is provided on the inlet side of the burner, and a first valve is provided on the inlet side of the electric heater; A third valve is provided between the high-pressure cooler and the first low-pressure cooler, and a fourth valve is provided between the first low-pressure cooler and the second low-pressure cooler; The central controller is electrically connected to the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve to adjust their opening degrees.

[0009] As a further description of the above technical solution: The liquid phase outlet of the water separator is connected to the water storage tank for recovering the moisture generated during combustion.

[0010] As a further description of the above technical solution: It also includes: pressure sensors and component detection sensors installed in the heat pump circulation pipeline; The central controller is configured to control the rotational speed or operating frequency of the carbon dioxide injection pump based on the detection value of the pressure sensor, so that the mass of carbon dioxide injected into the burner per unit time and the mass of carbon dioxide discharged by the carbon dioxide injection pump are kept in dynamic balance, and the high-pressure side pressure of the heat pump cycle is kept within a set threshold range.

[0011] As a further description of the above technical solution: A dynamic regulation method for a multi-source coupled heat pump wide-condition steam generation system includes the following steps: S1: The ground source heat pump module is driven by a new energy power generation unit. The circulating working fluid absorbs ground heat through the evaporator and is then compressed and heated by the compressor. S2: Multi-source coordinated regulation is carried out based on the power generation of new energy and the flow of associated gas. When the power generation of new energy is sufficient, the central controller adjusts the electric heater to run at full load and optimizes the parameters of the heat pump unit. When the output flow of associated gas exceeds the system demand, the booster is started to store the excess associated gas in the associated gas storage tank. When the flow of associated gas is too low or new energy is in short supply, the associated gas storage tank is used to supplement fuel and grid auxiliary power supply. S3: Implement staged heating and steam production. After the high-temperature circulating working fluid is heated by the electric heater and burner, it releases heat in stages within the system. High-pressure steam is generated by the high-pressure water pump and high-pressure cooler, and low-pressure steam is generated by the low-pressure water pump and second low-pressure cooler.

[0012] As a further description of the above technical solution: The pressure range of the high-pressure steam is 1.2~4.0MPa, and the temperature range is 194~250℃. The pressure range of the low-pressure steam is 0.1~0.4MPa, and the temperature range is 99~151℃.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In this invention, by integrating three types of energy—chemical energy from associated gas in oil fields, electrical energy generated from new energy sources such as solar and wind power, and low-grade heat energy from ground sources—a ground-source heat pump provides the basic heat load. The temperature is increased by using electric heating from new energy power generation and combustion of associated gas. By configuring steam output terminals with different temperatures and pressures, the efficient cascade utilization of energy and steam production under wide operating conditions are achieved.

[0014] 2. In this invention, the CO2 in the combustion products of associated gas is injected into the depleted oil well for storage after passing through a compressor and a buffer tank, achieving zero-carbon emission combustion and eliminating the environmental pollution caused by traditional associated gas venting combustion. The load of the electric heater, the amount of associated gas combustion, and the valve opening can be dynamically adjusted by the central controller according to the fluctuation of new energy power generation and the change of associated gas flow. Combined with the buffer of the storage tank and the grid assistance, the stability of the steam output of the system under various operating conditions is ensured.

[0015] 3. In this invention, the water vapor generated by combustion participates in the heat pump cycle to release heat, and after being cooled and condensed, it is separated by a water separator and enters a water storage tank for recycling, which reduces the system's water consumption. It can simultaneously produce high-pressure steam (194~250℃) for crude oil refining and low-pressure steam (99~151℃) for domestic heating, meeting the diverse heat energy needs of the oilfield area. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system structure of the steam generation system based on a multi-source coupled heat pump with wide operating conditions proposed in this invention.

[0017] Figure 2 This is a flowchart of the dynamic adjustment method for a wide-condition steam generation system based on a multi-source coupled heat pump proposed in this invention.

[0018] Legend: 1. Evaporator; 2. Water separator; 3. Dryer; 4. Low-temperature regenerator; 5. Compressor; 6. High-temperature regenerator; 7. First valve; 8. Second valve; 9. Electric heater; 10. Burner; 11. High-pressure cooler; 12. First low-pressure cooler; 13. Third valve; 14. Second low-pressure cooler; 15. Fourth valve; 16. Throttling valve; 17. Water storage tank; 18. High-pressure water pump; 19. Low-pressure water pump; 20. Low-pressure steam buffer tank; 21. High-pressure steam buffer tank; 22. Purifier; 23. Booster; 24. Fifth valve; 25. Associated gas storage tank; 26. Sixth valve; 27. Fuel preheater; 28. Carbon dioxide buffer tank; 29. ​​Carbon dioxide injection pump. Detailed Implementation

[0019] 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.

[0020] Please see Figures 1-2 This invention provides a technical solution: a wide-condition steam generation system based on a multi-source coupled heat pump, comprising: The heat pump cycle subsystem includes an evaporator 1, a low-temperature regenerator 4, a compressor 5, a high-temperature regenerator 6 connected in sequence, and an electric heater 9 and a burner 10 connected in a branch line after the outlet of the high-temperature regenerator 6. After the outlets of the electric heater 9 and the burner 10 merge, they are sequentially connected to the high-pressure cooler 11, the first low-pressure cooler 12, the second low-pressure cooler 14, the throttle valve 16, and then back to the evaporator 1. The heat pump cycle subsystem also includes a water separator 2 and a dryer 3 connected between the second low-pressure cooler 14 and the throttle valve 16; The associated gas and carbon capture subsystem includes a purifier 22, a booster 23, an associated gas storage tank 25 and a fuel preheater 27 connected in sequence. Purifier 22 is used to receive associated gas from the oil field, and the outlet of fuel preheater 27 is connected to burner 10; Specifically: all solar thermal power generation, photovoltaic power generation, and wind power generation are directly supplied to the compressor 5, electric heater 9, carbon dioxide injection pump 29, and system auxiliary equipment of the ground source heat pump module, realizing the full and efficient utilization of new energy power generation. The system maintains linkage with the backup power grid and automatically supplements power supply only when the total amount of new energy power generation is insufficient, ensuring continuous and stable power supply.

[0021] It also includes a carbon dioxide buffer tank 28 and a carbon dioxide injection pump 29 connected to the outlet end of the compressor 5; The steam generation subsystem includes a water storage tank 17, a high-pressure water pump 18, a low-pressure water pump 19, a low-pressure steam buffer tank 20, and a high-pressure steam buffer tank 21. High-pressure water pump 18 sends water from water storage tank 17 into first low-pressure cooler 12 for preheating and then evaporates in high-pressure cooler 11 to generate high-pressure steam. Low-pressure water pump 19 sends water from water storage tank 17 into second low-pressure cooler 14 to evaporate and generate low-pressure steam; The energy supply and control subsystem includes a central controller and a new energy power generation unit; the new energy power generation unit is electrically connected to the compressor 5, the electric heater 9 and the carbon dioxide injection pump 29; the central controller is used to dynamically adjust the system operation according to the amount of new energy power generated and the associated gas flow.

[0022] The burner 10 is configured to directly discharge the high-temperature carbon dioxide and water vapor generated by the combustion of associated gas into the heat pump circulation pipeline to participate in the circulation; Part of the working fluid at the outlet of compressor 5 is guided to carbon dioxide buffer tank 28, and after being pressurized by carbon dioxide injection pump 29, it is used to inject into depleted oil wells for storage. Specifically: After impurities such as hydrogen sulfide are removed by purifier 22, associated gas enters burner 10 for combustion. The combustion products, carbon dioxide and water vapor, directly participate in subsequent cycles. The combustion product, carbon dioxide, enters carbon dioxide buffer tank 28 from compressor 5 outlet, and is then injected into depleted oil wells for storage via carbon dioxide injection pump 29.

[0023] The low-temperature regenerator 4 is configured to absorb the waste heat of the working fluid before the throttling valve 16 using the working fluid at the outlet of the evaporator 1. The high-temperature regenerator 6 is configured to absorb the waste heat of the working fluid at the outlet of the high-pressure cooler 11 using the working fluid at the outlet of the compressor 5. A second valve 8 is provided on the inlet side of the burner 10, and a first valve 7 is provided on the inlet side of the electric heater 9; A third valve 13 is provided between the high-pressure cooler 11 and the first low-pressure cooler 12, and a fourth valve 15 is provided between the first low-pressure cooler 12 and the second low-pressure cooler 14; the central controller is electrically connected to the first valve 7, the second valve 8, the third valve 13, the fourth valve 15, the fifth valve 24 and the sixth valve 26 respectively to adjust the opening degree.

[0024] Specifically: After absorbing low-grade heat from the ground source in the evaporator 1, the circulating working fluid enters the low-temperature regenerator 4 to absorb residual heat before throttling and depressurization. After being further pressurized and heated by the compressor 5, it enters the high-temperature regenerator 6. Then, it is split and enters the electric heater 9 and the burner 10 respectively. The electric heater 9 raises the temperature of the circulating working fluid. After the associated gas is burned by the burner 10, the high-temperature combustion products carbon dioxide and water vapor directly participate in the subsequent cycle. The high-temperature circulating working fluid then enters the high-pressure cooler 11. The high-pressure side water in the water storage tank 17 is pressurized by the high-pressure pump and enters the first low-pressure cooler 12 for initial heating. Then, it absorbs heat and evaporates in the high-pressure cooler 11 to produce high-pressure steam. The low-pressure side water in the water storage tank 17 is pressurized by the low-pressure pump and enters the second low-pressure cooler 14 to absorb heat and evaporate to produce low-pressure steam. The circulating working fluid then enters the low-temperature regenerator 4 and the throttling valve 16 respectively for cooling and depressurization, completing the heat pump cycle.

[0025] The liquid phase outlet of water separator 2 is connected to water storage tank 17 for recovering water generated during combustion; It also includes: pressure sensors and component detection sensors installed in the heat pump circulation pipeline; The central controller is configured to control the speed or opening frequency of the carbon dioxide injection pump 29 based on the detection value of the pressure sensor, so that the mass of carbon dioxide injected into the burner 10 per unit time and the mass of carbon dioxide discharged by the carbon dioxide injection pump 29 are kept in dynamic balance, and the high pressure side pressure of the heat pump cycle is kept within the set threshold range. Specifically: When the associated gas output exceeds the system's steam production requirements, the booster compressor 23 is activated to pressurize the associated gas and store it in the associated gas storage tank 25. When the renewable energy power generation is sufficient, the central controller adjusts the electric heater 9 to operate at full load, optimizes the heat pump unit's operating parameters, and maximizes the value of renewable energy. When the associated gas output is too low or there is a temporary shortage of renewable energy power generation, a combination of supplementary associated gas stored in the associated gas storage tank 25 and temporary auxiliary power supply from the power grid is used. At the same time, the renewable energy power generation and the associated gas combustion in the system are linked. When the total renewable energy power generation decreases or increases, the opening of the first valve 7 of the circulating working fluid on the electric heating side decreases or increases accordingly, and the opening of the second valve 8 of the circulating working fluid on the combustion side and the associated gas combustion in the oilfield increase or decrease accordingly. Through dynamic adjustment, the system's steam production is ensured to be stable.

[0026] In one embodiment, the system circulates carbon dioxide as the heat exchange medium to absorb low-grade underground heat energy.

[0027] In another embodiment, a dynamic adjustment method based on a multi-source coupled heat pump wide-condition steam generation system is also included, comprising the following steps: S1: The ground source heat pump module is driven by the new energy power generation unit. The circulating working fluid absorbs ground heat through the evaporator 1 and is compressed and heated by the compressor 5. S2: Multi-source coordinated regulation is carried out based on the power generation of new energy and the flow of associated gas. When the power generation of new energy is sufficient, the central controller adjusts the electric heater 9 to run at full load and optimizes the parameters of the heat pump unit. When the output flow of associated gas exceeds the system demand, the booster 23 is started to store the excess associated gas into the associated gas storage tank 25. When the flow of associated gas is too low or new energy is in short supply, the associated gas storage tank 25 is used to supplement fuel and grid auxiliary power supply. S3: Implement staged heating and steam production. After the high-temperature circulating working fluid is heated by the electric heater 9 and the burner 10, the heat is released in stages within the system. High-pressure steam is generated by the high-pressure water pump 18 and the high-pressure cooler 11, and low-pressure steam is generated by the low-pressure water pump 19 and the second low-pressure cooler 14.

[0028] The pressure range of the high-pressure steam is 1.2~4.0MPa, and the temperature range is 194~250℃. The pressure range of the low-pressure steam is 0.1~0.4MPa, and the temperature range is 99~151℃.

[0029] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A steam generation system based on a multi-source coupled heat pump with wide operating conditions, characterized in that, include: The heat pump cycle subsystem includes an evaporator (1), a low-temperature regenerator (4), a compressor (5), a high-temperature regenerator (6) connected in sequence, and an electric heater (9) and a burner (10) connected in a branch line after the outlet of the high-temperature regenerator (6). The outlets of the electric heater (9) and the burner (10) are connected in sequence to the high-pressure cooler (11), the first low-pressure cooler (12), the second low-pressure cooler (14), the throttle valve (16), and then back to the evaporator (1). The heat pump cycle subsystem also includes a water separator (2) and a dryer (3) connected between the second low-pressure cooler (14) and the throttle valve (16). The associated gas and carbon capture subsystem includes a purifier (22), a booster (23), a fifth valve (24), an associated gas storage tank (25), a sixth valve (26), and a fuel preheater (27) connected in sequence. The purifier (22) is used to receive associated gas from the oil field, and the outlet of the fuel preheater (27) is connected to the burner (10). It also includes a carbon dioxide buffer tank (28) and a carbon dioxide injection pump (29) connected to the outlet end of the compressor (5). The steam generation subsystem includes a water storage tank (17), a high-pressure water pump (18), a low-pressure water pump (19), a low-pressure steam buffer tank (20), and a high-pressure steam buffer tank (21). The high-pressure water pump (18) sends the water in the water storage tank (17) into the first low-pressure cooler (12) for preheating and then evaporates it through the high-pressure cooler (11) to generate high-pressure steam; The low-pressure water pump (19) sends water from the water storage tank (17) into the second low-pressure cooler (14) to evaporate and generate low-pressure steam; The energy supply and control subsystem includes a central controller and a new energy power generation unit; the new energy power generation unit is electrically connected to the compressor (5), the electric heater (9) and the carbon dioxide injection pump (29); the central controller is used to dynamically adjust the system operation according to the new energy power generation and the associated gas flow.

2. The wide-condition steam generation system based on a multi-source coupled heat pump according to claim 1, characterized in that, The burner (10) is configured to directly discharge the high-temperature carbon dioxide and water vapor generated by the combustion of associated gas into the heat pump circulation pipeline to participate in the circulation; Part of the working fluid at the outlet of the compressor (5) is guided to the carbon dioxide buffer tank (28), and after being pressurized by the carbon dioxide injection pump (29), it is used to inject into the depleted oil well for storage.

3. The wide-condition steam generation system based on a multi-source coupled heat pump according to claim 1, characterized in that, The low-temperature regenerator (4) is configured to absorb the waste heat of the working fluid before the throttling valve (16) by utilizing the working fluid at the outlet of the evaporator (1). The high-temperature regenerator (6) is configured to absorb the waste heat of the working fluid at the outlet of the high-pressure cooler (11) using the working fluid at the outlet of the compressor (5).

4. The wide-condition steam generation system based on a multi-source coupled heat pump according to claim 1, characterized in that, The burner (10) is provided with a second valve (8) at its inlet side, and the electric heater (9) is provided with a first valve (7) at its inlet side. A third valve (13) is provided between the high-pressure cooler (11) and the first low-pressure cooler (12), and a fourth valve (15) is provided between the first low-pressure cooler (12) and the second low-pressure cooler (14); the central controller is electrically connected to the first valve (7), the second valve (8), the third valve (13), the fourth valve (15), the fifth valve (24) and the sixth valve (26) respectively to adjust the opening degree.

5. The wide-condition steam generation system based on a multi-source coupled heat pump according to claim 1, characterized in that, The liquid phase outlet of the water separator (2) is connected to the water storage tank (17) for recovering the water generated during combustion.

6. The wide-condition steam generation system based on a multi-source coupled heat pump according to claim 1, characterized in that, Also includes: Pressure sensors and component detection sensors are installed in the heat pump circulation pipeline; The central controller is configured to control the rotation speed or opening frequency of the carbon dioxide injection pump (29) based on the detection value of the pressure sensor, so that the mass of carbon dioxide injected into the cycle by the burner (10) per unit time and the mass of carbon dioxide discharged by the carbon dioxide injection pump (29) are kept in dynamic balance, and the high pressure side pressure of the heat pump cycle is kept within the set threshold range.

7. A dynamic adjustment method for a multi-source coupled heat pump wide-condition steam generation system, applied to the multi-source coupled heat pump wide-condition steam generation system as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: The ground source heat pump module is driven by the new energy power generation unit. The circulating working fluid absorbs ground source heat through the evaporator (1) and is compressed and heated by the compressor (5). S2: Multi-source coordinated regulation is carried out based on the power generation of new energy and the flow of associated gas. When the power generation of new energy is sufficient, the central controller adjusts the electric heater (9) to run at full load and optimizes the parameters of the heat pump unit. When the output flow of associated gas exceeds the system demand, the booster (23) is started to store the excess associated gas in the associated gas storage tank (25). When the flow of associated gas is too low or new energy is in short supply, the associated gas storage tank (25) is used to supplement fuel and grid auxiliary power supply. S3: Implement staged heating and steam production. After the high-temperature circulating working fluid is heated by the electric heater (9) and the burner (10), it releases heat in stages within the system. High-pressure steam is generated by the high-pressure water pump (18) and the high-pressure cooler (11), and low-pressure steam is generated by the low-pressure water pump (19) and the second low-pressure cooler (14).

8. The dynamic adjustment method for a wide-condition steam generation system based on a multi-source coupled heat pump according to claim 7, characterized in that, The pressure range of the high-pressure steam is 1.2~4.0MPa, and the temperature range is 194~250℃. The pressure range of the low-pressure steam is 0.1~0.4MPa, and the temperature range is 99~151℃.

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