A waste heat recovery system and method based on condensation adsorption coupling

Abstract

The present application relates to the technical field of oil gas recovery, and discloses a waste heat recovery system and method based on condensation-adsorption coupling, which comprises an oil gas recovery module, a refrigeration module, a heat storage module and a nitrogen purge module, the refrigeration module outputs the surplus heat generated by the operation of the compressor to the heat storage module, and the heat storage module is responsible for dynamically distributing the stored waste heat according to the heat demand of the oil gas recovery module and the nitrogen purge module; by preferentially recovering the surplus heat generated by the lubricating oil of the compressor of the refrigeration system instead of the high-pressure exhaust heat of the compressor, the negative impact of the traditional waste heat recovery mode on the refrigeration efficiency is avoided, the cascade utilization of the waste heat of the refrigeration system and the waste cold of the cryogenic system is realized, the electric heater configuration of the adsorption system can be greatly reduced or cancelled, the load power of the exhaust heater of the cryogenic system is significantly reduced, the overall energy consumption of the system is effectively reduced under the premise of ensuring that the oil gas recovery meets the environmental protection standard, and the economic benefit of the oil gas recovery is improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas recovery technology, and in particular to a waste heat recovery system and method based on condensation adsorption coupling. Background Technology

[0002] Oil and gas recovery methods mainly include adsorption, absorption, cryogenic treatment, and membrane separation. Currently, single treatment methods are no longer sufficient to meet increasingly stringent emission requirements, thus leading to the development of various combined treatment processes. Among them, the combination of cryogenic treatment and adsorption has become the mainstream process in the market due to its advantages of high recovery rate and economic value recovery of oil and gas components.

[0003] However, in this mainstream combined process, each processing stage operates independently without an effective energy coupling mechanism, resulting in high overall energy consumption and hindering the economic benefits of oil and gas recovery. Specifically, cryogenic methods require cooling the gas to around -70°C to achieve high oil and gas recovery rates, while the low-temperature tail gas needs to be heated to 5°C~10°C before entering the adsorption unit. The high-quality cold energy generated during cryogenic processes and the energy consumption of subsequent heating processes constitute a double waste. At the same time, the compressor in the cryogenic refrigeration system generates a large amount of heat during operation, and existing technologies often dissipate this heat directly into the atmosphere through air fans, resulting in the unnecessary loss of high-quality thermal energy. In addition, the regeneration process of activated carbon in the adsorption system relies on high-temperature nitrogen purging to improve desorption efficiency. Existing technologies typically use room-temperature nitrogen purging or electric heaters to heat the nitrogen. The former results in poor desorption and incomplete regeneration, while the latter continuously consumes a large amount of electrical energy, further increasing the operating costs of the system.

[0004] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a waste heat recovery system based on condensation adsorption coupling, which realizes the cascade utilization of waste heat from the refrigeration system and waste cooling from the cryogenic system, and effectively reduces the overall energy consumption of the system while ensuring that the oil and gas recovery meets environmental protection standards for emissions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A waste heat recovery system based on condensation-adsorption coupling includes an oil and gas recovery module, a refrigeration module, a heat storage module, and a nitrogen purging module. The oil and gas recovery module is used to realize the condensation recovery of oil and gas, the adsorption and purification of tail gas, and the recovery of desorption gas. The cooling end of the refrigeration module is connected to the refrigerant input end of the oil and gas recovery module, the waste heat output end of the refrigeration module is connected to the heat input end of the heat storage module, the first heat output end of the heat storage module is connected to the tail gas heating end of the oil and gas recovery module, and the second heat output end of the heat storage module is connected to the heating end of the nitrogen purging module. The purging gas output end of the nitrogen purging module is connected to the purging gas inlet of the oil and gas recovery module.

[0007] In the waste heat recovery system, the oil and gas recovery module includes a multi-stage condensation unit, a tail gas heating unit, and an adsorption and desorption unit. The oil and gas input end of the multi-stage condensation unit is connected to the oil and gas inlet, and its oil and gas output end is connected to the cold side of the tail gas heating unit. The cooling end of the refrigeration module is connected to the refrigerant input end of the multi-stage condensation unit. The first hot side of the tail gas heating unit is connected to the first heat output end of the heat storage module, and its oil and gas output end is connected to the air inlet of the adsorption and desorption unit. The exhaust end of the adsorption and desorption unit is connected to the tail gas emission port, and its purge gas inlet is connected to the purge gas output end of the nitrogen purge module.

[0008] In the waste heat recovery system, the multi-stage condensation unit includes a primary oil-gas condenser, a secondary oil-gas condenser, and a tertiary oil-gas condenser connected in series. The oil-gas input end of the primary oil-gas condenser is connected to the oil-gas inlet, and the oil-gas output end of the tertiary oil-gas condenser is connected to the cold side of the exhaust gas heating unit. The refrigeration module includes a primary refrigeration unit, a secondary refrigeration unit, and a tertiary refrigeration unit with identical structures. The cooling supply end of the primary refrigeration unit is connected to the refrigerant input end of the primary oil-gas condenser, the cooling supply end of the secondary refrigeration unit is connected to the refrigerant input end of the secondary oil-gas condenser, and the cooling supply end of the tertiary refrigeration unit is connected to the refrigerant input end of the tertiary oil-gas condenser.

[0009] In the waste heat recovery system, the primary refrigeration unit includes a compressor, an air condenser, an expansion valve, and a heat recovery unit. The air condenser is connected to the first output end of the compressor, and its liquid refrigerant output end is connected to the refrigerant input end of the primary oil-gas condenser through the expansion valve. The refrigerant-side output end of the primary oil-gas condenser is connected to the suction end of the compressor. The refrigerant input end of the heat recovery unit is connected to the second output end of the compressor, and its refrigerant-side output end is connected to the suction end of the compressor. The heat transfer fluid side of the heat recovery unit is connected to the heat input end of the heat storage module.

[0010] In the waste heat recovery system, the heat storage module includes a heat storage unit and a circulation conveying unit; the return end of the heat storage unit is connected to the return port of the exhaust gas heating unit and the return port of the nitrogen purging module, respectively, and its output end is connected to the heat transfer fluid input end of the heat recovery unit; the input end of the circulation conveying unit is connected to the heat transfer fluid output end of the heat recovery unit, and its first heat output end and second heat output end are connected to the exhaust gas heating end of the exhaust gas heating unit and the heating end of the nitrogen purging module, respectively.

[0011] In the waste heat recovery system, the circulation conveying unit includes a circulation pump, a thermal storage liquid temperature sensor, and a tail gas heater regulating valve. The input end of the circulation pump is connected to the thermal fluid output end of the heat recovery unit, and its output end is connected to the tail gas heating end of the tail gas heating unit and the heating end of the nitrogen purging module, respectively. The thermal storage liquid temperature sensor is located at the output end of the circulation pump and is used to monitor the temperature of the thermal fluid in real time. The tail gas heater regulating valve is located on the connecting pipeline between the circulation pump and the tail gas heating unit and is used to dynamically adjust the opening of the connecting pipeline according to the temperature of the thermal fluid.

[0012] In the waste heat recovery system, the nitrogen purging module includes a nitrogen heating unit and a purging unit; the cold side of the nitrogen heating unit is used to connect to an external gas supply unit, and its hot side is connected to the second heat output terminal of the heat storage module; the input terminal of the purging unit is connected to the output terminal of the nitrogen heating unit, and its output terminal is connected to the purging gas inlet of the adsorption and desorption unit.

[0013] The present invention also provides a waste heat recovery method based on condensation adsorption coupling, wherein the waste heat recovery method is implemented based on any of the waste heat recovery systems described above; the waste heat recovery method includes: acquiring a preset exhaust threshold, a preset heat transfer threshold, and the real-time exhaust temperature of the compressor and the real-time heat transfer temperature of the heat storage liquid output by the heat storage module; adjusting the working state of the air condenser according to the comparison result of the real-time exhaust temperature and the preset exhaust threshold; and adjusting the connection state between the heat storage module and the exhaust gas heating unit and the nitrogen purging module respectively according to the comparison result of the real-time heat transfer temperature and the preset heat transfer threshold.

[0014] In the waste heat recovery method, adjusting the working state of the air condenser based on the comparison result between the real-time exhaust temperature and the preset exhaust threshold includes: the preset exhaust threshold includes an upper exhaust threshold and a lower exhaust threshold; when the real-time exhaust temperature is ≥ the upper exhaust threshold, the air condenser is controlled to start working; when the real-time exhaust temperature is ≤ the lower exhaust threshold, the air condenser is controlled to stop working.

[0015] In the waste heat recovery method, the heat storage module includes a tail gas heater regulating valve, and the heat storage module is connected to the tail gas heating end of the tail gas heating unit through the tail gas heater regulating valve. Adjusting the connection state between the heat storage module and the tail gas heating unit and the nitrogen purging module based on a comparison between the real-time heat transfer temperature and a preset heat transfer threshold includes: the preset heat transfer threshold includes a fully closed threshold, a heat transfer target control value, and a fully open threshold, and the fully closed threshold < the heat transfer target control value < the fully open threshold; when the real-time heat transfer temperature < the fully closed threshold, the tail gas heater regulating valve is closed, causing the heat storage module to stop heating the tail gas. The unit supplies thermal storage fluid only to the nitrogen purging module. When the fully closed threshold is less than or equal to the real-time heat transfer temperature and less than the fully open threshold, the exhaust gas heater regulating valve is gradually opened, and the thermal storage module simultaneously supplies thermal storage fluid to both the exhaust gas heating unit and the nitrogen purging module. When the exhaust gas heater regulating valve is open, if the real-time heat transfer temperature is less than or equal to the fully closed threshold, the real-time exhaust temperature is compared with the exhaust upper limit threshold. If the real-time exhaust temperature is less than the exhaust upper limit threshold, the air condenser is stopped. When the real-time heat transfer temperature is greater than or equal to the heat transfer target control value, the process returns to controlling the exhaust gas heater regulating valve to gradually open.

[0016] Beneficial effects: This invention provides a waste heat recovery system based on condensation-adsorption coupling, including an oil and gas recovery module, a refrigeration module, a heat storage module, and a nitrogen purging module. The refrigeration module outputs excess heat generated by the compressor to the heat storage module, which dynamically allocates the stored waste heat according to the heat demand of the oil and gas recovery module and the nitrogen purging module. By prioritizing the recovery of excess heat generated by the compressor lubricating oil in the refrigeration system, rather than the high-pressure exhaust heat of the compressor, the negative impact of traditional waste heat recovery methods on refrigeration efficiency is avoided. This achieves the cascade utilization of waste heat from the refrigeration system and waste cooling from the cryogenic system, significantly reducing or eliminating the need for electric heaters in the adsorption system and significantly reducing the load power of the cryogenic system's exhaust gas heater. Under the premise of ensuring environmentally compliant emissions from oil and gas recovery, this system effectively reduces overall energy consumption and improves the economic benefits of oil and gas recovery. Attached Figure Description

[0017] Figure 1 The system structure diagram of the waste heat recovery system provided by the present invention; Figure 2 The present invention provides a logical flowchart of the waste heat recovery method.

[0018] Explanation of main component symbols: 11-First-stage oil-gas condenser, 12-Second-stage oil-gas condenser, 13-Third-stage oil-gas condenser, 14-Tail gas heater, 15-Adsorption tank A, 16-Adsorption tank B, 17-Vacuum pump, 21-Compressor, 22-Exhaust temperature sensor, 23-Air condenser, 24-Expansion valve, 25-Heat recovery unit, 31-Heat storage tank, 32-Circulation pump, 33-Heat storage liquid temperature sensor, 34-Tail gas heater regulating valve, 41-Nitrogen heater, 42-Heated nitrogen pipeline. Detailed Implementation

[0019] This invention provides a waste heat recovery system and method based on condensation adsorption coupling. To make the objectives, technical solutions and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] In the description of this invention, it should be understood that the terms "installation" and "connection" should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] like Figure 1 As shown, this invention provides a waste heat recovery system based on condensation-adsorption coupling, including an oil and gas recovery module, a refrigeration module, a heat storage module, and a nitrogen purging module. The oil and gas recovery module is used to realize the condensation recovery of oil and gas, tail gas adsorption purification, and desorption gas recovery. The cooling end of the refrigeration module is connected to the refrigerant input end of the oil and gas recovery module, the waste heat output end of the refrigeration module is connected to the heat input end of the heat storage module, the first heat output end of the heat storage module is connected to the tail gas heating end of the oil and gas recovery module, and the second heat output end of the heat storage module is connected to the heating end of the nitrogen purging module. The purging gas output end of the nitrogen purging module is connected to the purging gas inlet of the oil and gas recovery module.

[0022] In this embodiment, the oil and gas recovery module is responsible for completing the entire process of oil and gas condensation and recovery, tail gas adsorption and purification, and desorption gas recovery; the refrigeration module provides a gradient cold source for oil and gas condensation through refrigerant circulation, and outputs the excess heat generated by the compressor 21 to the heat storage module; the heat storage module is responsible for storing the waste heat output by the refrigeration module and dynamically distributing it according to the needs of each heat-using unit; the nitrogen purging module provides a hot nitrogen source for adsorbent regeneration, ensuring the continuous and stable operation of the adsorption system; the four modules are physically connected through medium pipelines and interact through control signal lines, forming an energy closed loop of refrigeration, heat storage, and heat use, alleviating the problem of independent energy and serious waste in each link of the existing combined process.

[0023] This invention discloses a waste heat recovery system based on condensation adsorption coupling, including an oil and gas recovery module, a refrigeration module, a heat storage module, and a nitrogen purging module. The refrigeration module outputs the excess heat generated by the compressor 21 to the heat storage module, which dynamically allocates the stored waste heat according to the heat demand of the oil and gas recovery module and the nitrogen purging module. By prioritizing the recovery of excess heat generated by the lubricating oil of the compressor 21 in the refrigeration system, rather than the high-pressure exhaust heat of the compressor 21, the negative impact of traditional waste heat recovery methods on refrigeration efficiency is avoided. This achieves the cascade utilization of waste heat from the refrigeration system and waste cooling from the cryogenic system, which can significantly reduce or eliminate the configuration of electric heaters in the adsorption system and significantly reduce the load power of the cryogenic system exhaust gas heater 14. Under the premise of ensuring that the oil and gas recovery meets environmental emission standards, it effectively reduces the overall energy consumption of the system and improves the economic benefits of oil and gas recovery.

[0024] In some implementations, such as Figure 1 As shown, the oil and gas recovery module includes a multi-stage condensation unit, an exhaust gas heating unit, and an adsorption and desorption unit. The oil and gas input end of the multi-stage condensation unit is connected to the oil and gas inlet, and its oil and gas output end is connected to the cold side of the exhaust gas heating unit. The cooling end of the refrigeration module is connected to the refrigerant input end of the multi-stage condensation unit. The first hot side of the exhaust gas heating unit is connected to the first heat output end of the heat storage module, and its oil and gas output end is connected to the air inlet of the adsorption and desorption unit. The exhaust end of the adsorption and desorption unit is connected to the exhaust gas emission port, and its purge gas inlet is connected to the purge gas output end of the nitrogen purge module.

[0025] In this embodiment, the exhaust gas heating unit includes an exhaust gas heater 14 and an exhaust gas temperature sensor. The exhaust gas heater 14 has two independent heat-side input terminals. The first heat-side input terminal is connected to the first heat output terminal of the heat storage module, and the second heat-side input terminal is used to connect to an external auxiliary heating device, which can be an electric heater or a steam heater. The oil and gas output terminal of the exhaust gas heater 14 is connected to the air inlet of the adsorption and desorption unit. The exhaust gas temperature sensor is installed on the oil and gas output pipeline of the exhaust gas heater 14 to monitor the temperature of the heated exhaust gas in real time. The adsorption and desorption unit includes adsorption tank A15, adsorption tank B16, vacuum pump 17, and desorption gas pipeline of vacuum pump 17 arranged in parallel. The air inlets of the two adsorption tanks are connected to the oil and gas output end of the exhaust gas heater 14, and the exhaust ends are connected to the exhaust gas emission port that meets the standards. The desorption gas ports are connected to the desorption gas pipeline of vacuum pump 17. The desorption gas pipeline of vacuum pump 17 is connected to the front end of the oil and gas recovery system after passing through vacuum pump 17. The purge gas inlets of the two adsorption tanks are connected to the purge gas output end of the nitrogen purge module.

[0026] In this embodiment, the exhaust gas heater 14 adopts a dual-heat-source collaborative design. The main heat source is the waste heat from the refrigeration system recovered by the thermal storage module, while the auxiliary heat source retains the original external heating device. The two are dynamically distributed in terms of load through a proportional regulating valve group. The process characteristics of the adsorption method show that the lower the oil and gas temperature during the adsorption stage, the greater the adsorption capacity of the activated carbon and the better the adsorption effect. During the desorption stage, the higher the activated carbon temperature, the faster the oil and gas desorption rate and the more complete the desorption. Based on this characteristic, the external auxiliary heating device can adopt a low-load design. When the temperature of the thermal storage liquid is too low and the waste heat supply is insufficient, the exhaust gas heater 14 relies on the low-load external auxiliary heat source for heating. At this time, the temperature of the heated exhaust gas can be appropriately lower than the conventional process requirement of 5℃~10℃. The lower exhaust gas temperature is actually beneficial to the adsorption stage of activated carbon, improving adsorption efficiency. At the same time, the nitrogen purging uses hot nitrogen, which can provide sufficient heat to the activated carbon in the desorption stage, compensating for the reduced desorption effect that may be caused by the low temperature of activated carbon in the adsorption stage, and achieving a balance between adsorption and desorption performance. When the temperature of the thermal storage fluid is sufficient, the heat transfer fluid output by the thermal storage module undertakes the main function of heating the exhaust gas, and the external auxiliary heat source can reduce the load or even stop operation, thereby saving energy consumption. It can be seen that the dual heat source low load design not only ensures the operational stability of the system under extreme conditions, but also makes full use of waste heat resources, and improves the oil and gas recovery efficiency by taking advantage of the characteristics of low temperature adsorption, forming a synergistic optimization of energy utilization and treatment effect.

[0027] In some implementations, such as Figure 1 As shown, the multi-stage condensing unit includes a first-stage oil-gas condenser 11, a second-stage oil-gas condenser 12, and a third-stage oil-gas condenser 13 connected in series. The oil-gas input end of the first-stage oil-gas condenser 11 is connected to the oil-gas inlet, and the oil-gas output end of the third-stage oil-gas condenser 13 is connected to the cold side of the exhaust gas heating unit. The refrigeration module includes a first-stage refrigeration unit, a second-stage refrigeration unit, and a third-stage refrigeration unit with identical structures. The cooling supply end of the first-stage refrigeration unit is connected to the refrigerant input end of the first-stage oil-gas condenser 11, the cooling supply end of the second-stage refrigeration unit is connected to the refrigerant input end of the second-stage oil-gas condenser 12, and the cooling supply end of the third-stage refrigeration unit is connected to the refrigerant input end of the third-stage oil-gas condenser 13.

[0028] In this embodiment, the cooling supply end of the first-stage refrigeration unit is connected to the refrigerant input end of the first-stage oil-gas condenser 11, providing it with a cold source of approximately +5°C for condensing high-boiling-point components in the oil-gas; the cooling supply end of the second-stage refrigeration unit is connected to the refrigerant input end of the second-stage oil-gas condenser 12, providing it with a cold source of approximately -30°C for condensing medium-boiling-point components in the oil-gas; the cooling supply end of the third-stage refrigeration unit is connected to the refrigerant input end of the third-stage oil-gas condenser 13, providing it with a cold source of approximately -70°C for condensing low-boiling-point components in the oil-gas; the gradient refrigeration structure of the multi-stage condensation unit can achieve staged condensation according to the boiling point differences of the oil-gas components, improve condensation recovery efficiency, and reduce the overall energy consumption of the refrigeration system.

[0029] In some implementations, such as Figure 1 As shown, Figure 1 The diagram only shows the connection structure of the secondary refrigeration unit connected to the secondary oil-gas condenser 12. In reality, each oil-gas condenser is connected to a corresponding refrigeration unit, and the three refrigeration units have the same structure. exist Figure 1 In this configuration, the secondary refrigeration unit includes a compressor 21, an air condenser 23, an expansion valve 24, and a heat recovery unit 25. The air condenser 23 is connected to the first output end of the compressor 21, and its liquid refrigerant output end is connected to the refrigerant input end of the secondary oil-gas condenser 12 through the expansion valve 24. The refrigerant-side output end of the secondary oil-gas condenser 12 is connected to the suction end of the compressor 21. The refrigerant input end of the heat recovery unit 25 is connected to the second output end of the compressor 21, and its refrigerant-side output end is connected to the suction end of the compressor 21. The heat transfer fluid side of the heat recovery unit 25 is connected to the heat input end of the heat storage module.

[0030] In this embodiment, the compressor 21 is a positive displacement refrigeration compressor, with its suction end connected to the refrigerant-side output end of the oil-gas condenser and its discharge end connected to the refrigerant input end of the air condenser 23; the heat recovery unit 25 is a lubricating oil-heat transfer liquid shell-and-tube heat exchanger, installed in the lubricating oil circulation loop of the compressor 21, with the lubricating oil outlet of the compressor 21 connected to the lubricating oil-side input end of the heat recovery unit 25, and the lubricating oil-side output end of the heat recovery unit 25 connected to the lubricating oil return port of the compressor 21; the air condenser 23 is a forced air-cooled shell-and-tube heat exchanger, equipped with multiple parallel axial flow fan units, and its liquid refrigerant output end is connected to the refrigerant input end of the oil-gas condenser through an expansion valve 24; In actual operation, compressor 21 compresses the refrigerant to produce high-temperature, high-pressure gas, which enters air condenser 23. Forced air cooling by the axial flow fan unit condenses it into a liquid state. After being throttled and depressurized by expansion valve 24, it enters oil-gas condenser, absorbs heat from the oil and gas, vaporizes, and returns to the suction end of compressor 21 to complete the refrigeration cycle. Simultaneously, during compressor 21 operation, the lubricating oil absorbs the heat generated by internal friction and refrigerant compression, becoming high-temperature lubricating oil that enters heat recovery unit 25. It transfers heat to the heat transfer fluid, cools down, and returns to compressor 21 to continue participating in the lubrication cycle. By using compressor 21 lubricating oil as a waste heat source, instead of high-pressure exhaust from compressor 21, the problems of insufficient subcooling on the condenser side and decreased refrigeration efficiency caused by using high-pressure exhaust as a heat source in traditional methods are avoided. This achieves efficient waste heat recovery without significantly affecting the performance of the original refrigeration system.

[0031] In some implementations, such as Figure 1 As shown, the heat storage module includes a heat storage unit and a circulation conveying unit; the return end of the heat storage unit is connected to the return port of the exhaust gas heating unit and the return port of the nitrogen purging module, respectively, and its output end is connected to the heat transfer fluid input end of the heat recovery unit 25; the input end of the circulation conveying unit is connected to the heat transfer fluid output end of the heat recovery unit 25, and its first heat output end and second heat output end are connected to the exhaust gas heating end of the exhaust gas heating unit and the heating end of the nitrogen purging module, respectively.

[0032] In this embodiment, the heat storage unit includes a vertical heat storage tank 31 with a polyurethane insulation layer. Its return end is connected to the heat transfer liquid return port of the exhaust gas heating unit and the heat transfer liquid return port of the nitrogen purging module through pipelines, and its output end is connected to the heat transfer liquid input end of the heat recovery unit 25 of each stage of the refrigeration unit through pipelines. In actual operation, the low-temperature heat transfer fluid in the heat storage tank 31 is usually a 60% ethylene glycol aqueous solution, which is transported through pipelines to the heat recovery unit 25 of each refrigeration unit. After absorbing the heat from the lubricating oil of the compressor 21, it becomes a high-temperature heat transfer fluid, which flows into the circulation conveying unit and is then transported by the circulation conveying unit to the exhaust gas heating unit and the nitrogen purging module respectively. After releasing heat, the low-temperature heat transfer fluid flows back to the heat storage tank 31 to complete the heat storage cycle. By centrally storing the waste heat recovered by each refrigeration unit through the heat storage tank 31, the unified management and dynamic distribution of waste heat are realized, which improves the flexibility and stability of waste heat utilization.

[0033] In some implementations, such as Figure 1As shown, the circulating conveying unit includes a circulating pump 32, a thermal storage liquid temperature sensor 33, and a tail gas heater regulating valve 34. The input end of the circulating pump 32 is connected to the thermal fluid output end of the heat recovery unit 25, and its output end is connected to the tail gas heating end of the tail gas heating unit and the heating end of the nitrogen purging module, respectively. The thermal storage liquid temperature sensor 33 is located at the output end of the circulating pump 32 and is used to monitor the temperature of the thermal fluid in real time. The tail gas heater regulating valve 34 is located on the connecting pipeline between the circulating pump 32 and the tail gas heating unit and is used to dynamically adjust the opening of the connecting pipeline according to the temperature of the thermal fluid.

[0034] In this embodiment, the circulating pump 32 is a shielded centrifugal circulating pump 32. Its input end is connected to the heat transfer fluid output end of the heat recovery unit 25 of each stage of the refrigeration unit through a main pipeline. Its output end is divided into two paths: one path is connected to the heating end of the nitrogen purging module through a pipeline, and the other path is connected to the tail gas heating end of the tail gas heating unit through the tail gas heater regulating valve 34. The heat storage fluid temperature sensor 33 is a platinum resistance temperature sensor, installed on the main pipeline at the output end of the circulating pump 32, and is used to monitor the overall temperature of the heat transfer fluid output by the system in real time. The tail gas heater regulating valve 34 is an electric proportional regulating valve with 0%-100% continuous adjustment capability and fast response characteristics. Its signal input end is connected to the controller, and the valve opening is dynamically adjusted according to the feedback signal of the heat storage fluid temperature sensor 33. Through the interlocking control of the heat storage fluid temperature sensor 33 and the tail gas heater regulating valve 34, the heat distribution ratio of the tail gas heating unit and the nitrogen purging module can be dynamically adjusted according to the change of waste heat recovery, so as to realize the on-demand utilization of waste heat and ensure the stability and economy of system operation.

[0035] In some implementations, such as Figure 1 As shown, the nitrogen purging module includes a nitrogen heating unit and a purging unit; the cold side of the nitrogen heating unit is used to connect to an external gas supply unit, and its hot side is connected to the second heat output terminal of the heat storage module; the input terminal of the purging unit is connected to the output terminal of the nitrogen heating unit, and its output terminal is connected to the purging gas inlet of the adsorption and desorption unit.

[0036] In this embodiment, the nitrogen heating unit includes a nitrogen heater 41, whose cold-side input end is connected to an external gas supply unit via a pipeline, the external gas supply unit being used to provide purging nitrogen; the hot-side input end of the nitrogen heating unit is connected to the second heat output end of the heat storage module circulation conveying unit via a pipeline, its hot-side output end is connected to the return end of the heat storage module heat storage unit via a pipeline, and its nitrogen output end is connected to the input end of the purging unit; the purging unit includes a heated nitrogen pipeline 42 and multiple sets of electromagnetic switching valves, the output end of the heated nitrogen pipeline 42 being connected to the purging gas inlets of the two adsorption tanks in the adsorption desorption unit via electromagnetic switching valves respectively; using the waste heat recovered by the heat storage module to heat the nitrogen significantly reduces the usage time and power of the electric heater in the traditional process, reducing the system's operating energy consumption; at the same time, hot nitrogen purging can significantly improve the desorption efficiency of activated carbon, ensure sufficient regeneration of the adsorbent, extend the service life of the adsorbent, and help the tail gas achieve long-term stable emission standards.

[0037] like Figure 2 As shown, the present invention also provides a waste heat recovery method based on condensation adsorption coupling, wherein the waste heat recovery method is implemented based on any of the waste heat recovery systems described above; the waste heat recovery method includes: 101. Obtain the preset exhaust threshold, the preset heat transfer threshold, the real-time exhaust temperature of the compressor 21, and the real-time heat transfer temperature of the heat storage liquid output by the heat storage module, respectively; the real-time exhaust temperature of the compressor 21 is obtained by the exhaust temperature sensor 22 set at the exhaust end of the compressor 21.

[0038] 102. Adjust the working state of the air condenser 23 according to the comparison result between the real-time exhaust temperature and the preset exhaust threshold. 103. Based on the comparison result between the real-time heat transfer temperature and the preset heat transfer threshold, adjust the connection status between the heat storage module and the exhaust gas heating unit and the nitrogen purging module respectively.

[0039] In existing technologies, the air condenser 23 operates continuously to dissipate most of the heat generated by the compressor 21, while exhaust gas heating and nitrogen heating mainly rely on electric heaters, resulting in a double waste of energy. This invention provides a waste heat recovery method that establishes a dual-parameter independent interlocking control mechanism. On the one hand, the operating state of the air condenser 23 is adjusted according to the exhaust temperature of the compressor 21, and the air condenser 23 is only activated to dissipate excess heat when the temperature of the compressor 21 is too high or when there is excess waste heat in the system, maximizing the recovery of excess heat generated by the compressor 21. On the other hand, the heat distribution ratio of the heat storage module is dynamically adjusted according to the temperature of the heat storage liquid, prioritizing the nitrogen heating needs required for activated carbon regeneration, with the remaining heat used for exhaust gas heating. This method achieves precise recovery and on-demand distribution of waste heat, significantly reducing the load on the exhaust gas heater 14 without fundamentally changing the original oil and gas recovery process, reducing oil and gas recovery efficiency and emission compliance rate, effectively alleviating the serious energy waste problem of existing combined processes, and helping to improve the economic benefits of the oil and gas recovery system.

[0040] In some embodiments, adjusting the operating state of the air condenser 23 based on a comparison between the real-time exhaust temperature and a preset exhaust threshold includes: 201. The preset exhaust thresholds include an upper exhaust threshold and a lower exhaust threshold; 202. When the real-time exhaust temperature is greater than or equal to the upper limit threshold of the exhaust temperature, the air condenser 23 is controlled to start working; 203. When the real-time exhaust temperature is less than or equal to the lower limit threshold of the exhaust temperature, the air condenser 23 shall be stopped from working.

[0041] In this embodiment, the air condenser 23 is a forced air-cooled shell and tube heat exchanger, and its working state is adjusted by controlling the start and stop of the matching axial flow fan unit; when the air condenser 23 stops working, the refrigerant always flows through the heat exchange tube bundle of the air condenser 23 without cutting off the refrigerant flow path, thus ensuring the continuity and stability of the refrigeration cycle. The preset upper limit threshold for exhaust is 80℃, and the preset lower limit threshold is 70℃. This threshold range is set according to the optimal operating temperature range of the lubricating oil of the refrigeration compressor 21. The optimal operating temperature of the lubricating oil of the compressor 21 is usually 70℃~80℃. Within this temperature range, the lubricating oil has a suitable viscosity, which can ensure the lubrication effect of the compressor 21 and extend the service life of the compressor 21. At the same time, this temperature range can provide a stable waste heat source for the heat storage system and avoid large changes in the temperature of the heat storage liquid due to temperature fluctuations of the compressor 21, which would affect the stable operation of subsequent heat-using units. When the exhaust temperature of compressor 21 exceeds 80°C, the air condenser 23 is activated for forced air cooling to prevent compressor 21 from overheating and being damaged; when the exhaust temperature drops to 70°C, the air condenser 23 is stopped to reduce heat loss to the atmosphere and increase waste heat recovery.

[0042] In some embodiments, the heat storage module includes an exhaust gas heater regulating valve 34, and the heat storage module is connected to the exhaust gas heating end of the exhaust gas heating unit through the exhaust gas heater regulating valve 34; adjusting the connection state between the heat storage module and the exhaust gas heating unit and the nitrogen purging module respectively based on the comparison result of the real-time heat transfer temperature and the preset heat transfer threshold includes: 301. The preset heat transfer threshold includes a fully closed threshold, a heat transfer target control value, and a fully open threshold, and the fully closed threshold < the heat transfer target control value < the fully open threshold; In this embodiment, the preset fully closed threshold is 55°C, the heat transfer target control value is 60°C, and the fully open threshold is 65°C. This temperature range is set according to the temperature required for exhaust gas heating (5°C~10°C) and the temperature required for nitrogen heating (60°C~70°C). The nitrogen heating temperature directly affects the desorption efficiency of activated carbon and is a core factor in ensuring stable adsorption operation and compliant exhaust gas emissions. Therefore, it is set as the priority heat demand. Exhaust gas heating raises the temperature of the -70°C exhaust gas to 5°C~10°C. The total heat demand is relatively low, so it is set as the secondary heat demand.

[0043] 302. When the real-time heat transfer temperature is less than the full-off threshold, the tail gas heater regulating valve 34 is controlled to close, so that the heat storage module stops supplying heat storage liquid to the tail gas heating unit and only supplies heat storage liquid to the nitrogen purging module, so as to prioritize the heat demand for activated carbon regeneration. 303. When the fully closed threshold is less than or equal to the real-time heat transfer temperature and less than the fully open threshold, the tail gas heater regulating valve 34 is gradually opened, and the heat storage module simultaneously supplies heat storage liquid to the tail gas heating unit and the nitrogen purging module. In this embodiment, when the full-close threshold is less than or equal to the real-time heat transfer temperature and the heat transfer target control value, the tail gas heater regulating valve 34 is gradually opened from 0%, and the heat storage module simultaneously supplies heat storage liquid to both units. The valve opening increases linearly with the temperature increase. When the heat transfer target control value is less than or equal to the real-time heat transfer temperature and the full-open threshold, the valve opening continues to increase linearly to 100%. When the real-time heat transfer temperature is greater than or equal to the full-open threshold, the tail gas heater regulating valve 34 is kept fully open to maximize the use of waste heat for tail gas heating.

[0044] 304. When the exhaust gas heater regulating valve 34 is in the open state, if the real-time heat transfer temperature is detected to be ≤ the full-close threshold, the real-time exhaust temperature is compared with the exhaust upper limit threshold. 305. If the real-time exhaust temperature is less than the upper limit threshold of the exhaust temperature, then control the air condenser 23 to stop operating; 306. When the real-time heat transfer temperature is greater than or equal to the heat transfer target control value, return to the execution control to gradually open the tail gas heater regulating valve 34; In this embodiment, when the exhaust gas heater regulating valve 34 is open and the real-time heat transfer temperature drops to the fully closed threshold, the controller first performs an exhaust temperature judgment step. If the real-time exhaust temperature is less than the exhaust upper limit threshold, the air condenser 23 is stopped to reduce heat loss to the atmosphere and increase waste heat recovery. After waiting 60 seconds, the heat storage liquid temperature is remeasured. This delay time is used to filter out instantaneous fluctuation signals from the temperature sensor to prevent equipment wear and system instability caused by frequent valve opening and closing. If the remeasured temperature is less than the fully closed threshold, it indicates that the waste heat recovery is still insufficient to meet the dual-path requirements. When heating demand is met, the tail gas heater regulating valve 34 is completely closed, and all waste heat is prioritized to supply the nitrogen purging module to ensure the continuity of the activated carbon regeneration process and the desorption effect, and to avoid the decrease in adsorption efficiency and excessive tail gas emissions due to insufficient regeneration. If the retested temperature is greater than or equal to the full-close threshold, the opening of the tail gas heater regulating valve 34 is locked at the moment before the temperature drops to the full-close threshold, and the current heating distribution state is maintained until the temperature of the heat storage liquid is greater than or equal to the heat transfer target control value. Then, the linear regulation function of the tail gas heater regulating valve 34 is restored, and the opening is gradually increased to meet the tail gas heating demand. Furthermore, when the temperature of the thermal storage liquid is greater than or equal to the fully open threshold and the tail gas heater regulating valve 34 is kept fully open, if the real-time exhaust temperature of the compressor 21 is still lower than the upper limit threshold, the controller starts the air condenser 23 to dissipate excess heat from the system and prevent the thermal storage liquid temperature from being too high, which could lead to overheating of the tail gas or excessive nitrogen temperature, thus affecting the stability of the adsorption process. When the real-time exhaust temperature of the compressor 21 is greater than or equal to the upper limit threshold, the controller will forcibly start the air condenser 23 regardless of the temperature range of the thermal storage liquid to ensure the safe operation of the compressor 21 and prevent equipment damage due to overheating.

[0045] It is understood that those skilled in the art can make equivalent substitutions or changes to the technical solution and inventive concept of the present invention, and all such changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A waste heat recovery system based on condensation-adsorption coupling, characterized in that, It includes an oil and gas recovery module, a refrigeration module, a heat storage module, and a nitrogen purging module. The oil and gas recovery module is used to realize the condensation and recovery of oil and gas, the adsorption and purification of exhaust gas, and the recovery of desorption gas. The cooling end of the refrigeration module is connected to the refrigerant input end of the oil and gas recovery module, the waste heat output end of the refrigeration module is connected to the heat input end of the heat storage module, the first heat output end of the heat storage module is connected to the exhaust gas heating end of the oil and gas recovery module, and the second heat output end of the heat storage module is connected to the heating end of the nitrogen purging module. The purging gas output end of the nitrogen purging module is connected to the purging gas inlet of the oil and gas recovery module.

2. The waste heat recovery system according to claim 1, characterized in that, The oil and gas recovery module includes a multi-stage condensation unit, an exhaust gas heating unit, and an adsorption and desorption unit. The oil and gas input end of the multi-stage condensation unit is connected to the oil and gas inlet, and its oil and gas output end is connected to the cold side of the exhaust gas heating unit. The cooling end of the refrigeration module is connected to the refrigerant input end of the multi-stage condensation unit. The first hot side of the exhaust gas heating unit is connected to the first heat output end of the heat storage module, and its oil and gas output end is connected to the air inlet of the adsorption and desorption unit. The exhaust end of the adsorption and desorption unit is connected to the exhaust gas emission port, and its purge gas inlet is connected to the purge gas output end of the nitrogen purge module.

3. The waste heat recovery system according to claim 2, characterized in that, The multi-stage condensing unit includes a primary oil-gas condenser, a secondary oil-gas condenser, and a tertiary oil-gas condenser connected in series. The oil-gas input end of the primary oil-gas condenser is connected to the oil-gas inlet, and the oil-gas output end of the tertiary oil-gas condenser is connected to the cold side of the exhaust gas heating unit. The refrigeration module includes a primary refrigeration unit, a secondary refrigeration unit, and a tertiary refrigeration unit with identical structures. The cooling supply end of the primary refrigeration unit is connected to the refrigerant input end of the primary oil-gas condenser, the cooling supply end of the secondary refrigeration unit is connected to the refrigerant input end of the secondary oil-gas condenser, and the cooling supply end of the tertiary refrigeration unit is connected to the refrigerant input end of the tertiary oil-gas condenser.

4. The waste heat recovery system according to claim 3, characterized in that, The primary refrigeration unit includes a compressor, an air condenser, an expansion valve, and a heat recovery unit. The air condenser is connected to the first output end of the compressor, and its liquid refrigerant output end is connected to the refrigerant input end of the primary oil-gas condenser through the expansion valve. The refrigerant-side output end of the primary oil-gas condenser is connected to the suction end of the compressor. The refrigerant input end of the heat recovery unit is connected to the second output end of the compressor, and its refrigerant-side output end is connected to the suction end of the compressor. The heat transfer fluid side of the heat recovery unit is connected to the heat input end of the heat storage module.

5. The waste heat recovery system according to claim 4, characterized in that, The heat storage module includes a heat storage unit and a circulation conveying unit; the return end of the heat storage unit is connected to the return port of the exhaust gas heating unit and the return port of the nitrogen purging module, respectively, and its output end is connected to the heat transfer fluid input end of the heat recovery unit; the input end of the circulation conveying unit is connected to the heat transfer fluid output end of the heat recovery unit, and its first heat output end and second heat output end are connected to the exhaust gas heating end of the exhaust gas heating unit and the heating end of the nitrogen purging module, respectively.

6. The waste heat recovery system according to claim 5, characterized in that, The circulating conveying unit includes a circulating pump, a thermal storage liquid temperature sensor, and an exhaust gas heater regulating valve. The input end of the circulating pump is connected to the thermal fluid output end of the heat recovery unit, and its output end is connected to the exhaust gas heating end of the exhaust gas heating unit and the heating end of the nitrogen purging module, respectively. The thermal storage liquid temperature sensor is located at the output end of the circulating pump and is used to monitor the temperature of the thermal storage liquid in real time. The exhaust gas heater regulating valve is located on the connecting pipeline between the circulating pump and the exhaust gas heating unit and is used to dynamically adjust the opening of the connecting pipeline according to the temperature of the thermal storage liquid.

7. The waste heat recovery system according to claim 5, characterized in that, The nitrogen purging module includes a nitrogen heating unit and a purging unit; the cold side of the nitrogen heating unit is used to connect to an external gas supply unit, and its hot side is connected to the second heat output terminal of the heat storage module; the input terminal of the purging unit is connected to the output terminal of the nitrogen heating unit, and its output terminal is connected to the purging gas inlet of the adsorption and desorption unit.

8. A waste heat recovery method based on condensation-adsorption coupling, characterized in that, The waste heat recovery method is implemented based on the waste heat recovery system as described in any one of claims 4-7; the waste heat recovery method includes: The preset exhaust threshold, preset heat transfer threshold, real-time exhaust temperature of the compressor, and real-time heat transfer temperature of the heat storage liquid output by the heat storage module are obtained respectively. The working state of the air condenser is adjusted based on the comparison between the real-time exhaust temperature and the preset exhaust threshold. Based on the comparison between the real-time heat transfer temperature and the preset heat transfer threshold, the connection status between the heat storage module and the exhaust gas heating unit and the nitrogen purging module is adjusted respectively.

9. The waste heat recovery method according to claim 8, characterized in that, Adjusting the operating state of the air condenser based on the comparison result between the real-time exhaust temperature and the preset exhaust threshold includes: The preset exhaust thresholds include an upper exhaust threshold and a lower exhaust threshold; When the real-time exhaust temperature is greater than or equal to the upper limit threshold of the exhaust temperature, the air condenser is controlled to start working; When the real-time exhaust temperature is less than or equal to the lower exhaust threshold, the air condenser is controlled to stop working.

10. The waste heat recovery method according to claim 9, characterized in that, The heat storage module includes an exhaust gas heater regulating valve, and the heat storage module is connected to the exhaust gas heating end of the exhaust gas heating unit through the exhaust gas heater regulating valve; adjusting the connection state between the heat storage module and the exhaust gas heating unit and the nitrogen purging module respectively according to the comparison result of the real-time heat transfer temperature and the preset heat transfer threshold includes: The preset heat transfer threshold includes a fully closed threshold, a heat transfer target control value, and a fully open threshold, wherein the fully closed threshold < the heat transfer target control value < the fully open threshold. When the real-time heat transfer temperature is less than the full-off threshold, the tail gas heater regulating valve is controlled to close, so that the heat storage module stops supplying heat storage liquid to the tail gas heating unit and only supplies heat storage liquid to the nitrogen purging module. When the fully closed threshold is less than or equal to the real-time heat transfer temperature and less than the fully open threshold, the tail gas heater regulating valve is gradually opened, and the heat storage module simultaneously supplies heat storage liquid to the tail gas heating unit and the nitrogen purging module. When the exhaust gas heater regulating valve is in the open state, if the real-time heat transfer temperature is detected to be less than or equal to the fully closed threshold, the real-time exhaust temperature is compared with the exhaust upper limit threshold. If the real-time exhaust temperature is less than the upper limit threshold for exhaust, then the air condenser is controlled to stop operating; When the real-time heat transfer temperature is greater than or equal to the heat transfer target control value, the process returns to control the exhaust gas heater regulating valve to open gradually.

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