Natural gas condensate dehydration tail gas treatment and residual energy cascade recovery system

Abstract

This invention relates to the field of petrochemical technology and discloses a natural gas condensation dehydration tail gas treatment and waste energy cascade recovery system, including a tail gas treatment unit, a waste heat cascade utilization unit, a condensate recovery unit, and an intelligent collaborative control unit. The system utilizes the waste heat from the water-containing tail gas in a tail gas-rich liquid tubular heat exchanger for primary preheating of the low-temperature rich liquid, followed by secondary heating using high-temperature flue gas from the reboiler via a flue gas waste heat recovery unit. This achieves cascaded heating of the ethylene glycol rich liquid, significantly reducing reboiler energy consumption. The condensate recovery unit collects the condensate precipitated during each stage of heat exchange and cooling and extracts and recovers the ethylene glycol component, achieving resource recycling. The intelligent collaborative control unit uses a multi-parameter sensor network and edge computing to dynamically adapt to operating conditions. This invention abandons the traditional high-energy-consuming tail gas incineration method, realizing tail gas resource utilization and deep waste heat recovery, significantly improving the energy-saving and environmental protection level of natural gas dehydration processes.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and in particular to a natural gas condensation and dehydration tail gas treatment and residual energy cascade recovery system. Background Technology

[0002] In the petrochemical industry, natural gas condensation dehydration technology has been widely adopted due to its significant advantages, including simple process, convenient operation, and suitability for large-scale production. Among condensation dehydration processes, the JT valve throttling and depressurization refrigeration dehydration and hydrocarbon removal process is commonly used. This process utilizes the principle of throttling expansion and cooling to condense and discharge gaseous water from natural gas through depressurization, ensuring that the dew point of exported natural gas meets standards. To prevent freezing of the low-temperature condensate after natural gas throttling and depressurization, an ethylene glycol solution is introduced before water separation (i.e., before the natural gas throttling process). The ethylene glycol dissolves in the condensate generated by natural gas throttling and depressurization, forming a rich liquid that enters the regeneration process. Furthermore, the ethylene glycol can be recycled through the regeneration process.

[0003] However, existing regeneration processes suffer from high energy consumption. In the JT valve purification process for natural gas, the fuel gas consumption in the reboiler and the combustion furnace constitutes the main energy consumption of the process. Specifically, the heating of the ethylene glycol-rich liquid to the required process temperature by the reboiler and the combustion of the separated tail gas in the combustion furnace before being released into the atmosphere are the two major energy-consuming stages. Existing technologies can no longer meet the high-level demands of the oil and gas production sector for deep energy conservation, efficient resource recovery, and intelligent adaptation. Summary of the Invention

[0004] This invention provides a natural gas condensation dehydration tail gas treatment and waste energy cascade recovery system. Based on the existing dehydration device, a tail gas treatment and waste energy cascade recovery device is added, including an intelligent collaborative control unit, a condensate recovery unit and a waste heat cascade utilization unit, forming a closed-loop system of "treatment-recovery-control-reuse". It can be seamlessly adapted to existing dehydration devices to achieve deep energy saving and carbon reduction and efficient resource utilization.

[0005] This invention provides a natural gas condensation dehydration tail gas treatment and waste heat cascade recovery system, including a tail gas treatment unit, a waste heat cascade utilization unit, a condensate recovery unit, and an intelligent collaborative control unit; The exhaust gas treatment unit includes an exhaust gas-rich liquid tubular heat exchanger (5) and an exhaust gas air cooler (16) connected in sequence by pipelines. The exhaust gas-rich liquid tubular heat exchanger (5) is provided with an exhaust gas inlet pipe (9), an exhaust gas intermediate pipe (14), a low-temperature rich liquid inlet pipe (1), and a low-temperature rich liquid outlet pipe (8). The water-containing exhaust gas discharged from the external natural gas dehydration process enters the exhaust gas-rich liquid tubular heat exchanger (5) through the exhaust gas inlet pipe (9) and exchanges heat with the ethylene glycol rich liquid entering through the low-temperature rich liquid inlet pipe (1) to perform the first stage of cooling on the water-containing exhaust gas. The air inlet of the exhaust gas air cooler (16) is connected to the exhaust gas intermediate pipe (14) and is used to perform the second stage of cooling on the exhaust gas after the first stage of cooling. The waste heat utilization unit includes a flue gas waste heat recovery unit (37); the flue gas waste heat recovery unit (37) is provided with a flue gas inlet pipe (42), a flue gas outlet pipe (49), a high-temperature rich liquid inlet pipe (33), and a high-temperature rich liquid outlet pipe (39); the high-temperature rich liquid inlet pipe (33) is connected to the low-temperature rich liquid outlet pipe (8); the flue gas inlet pipe (42) is used to introduce high-temperature flue gas generated by an external reboiler; the high-temperature flue gas exchanges heat with the ethylene glycol rich liquid that flows in after absorbing heat from the tail gas treatment unit, so as to perform stepped heating of the ethylene glycol rich liquid; the flue gas outlet pipe (49) is used to discharge the flue gas after heat exchange and cooling; the high-temperature rich liquid outlet pipe (39) is used to output the ethylene glycol rich liquid that has completed stepped heating to the reboiler. The condensate recovery unit includes a condensate separation and recovery device (57); the drain pipe (27) of the tail gas-rich tubular heat exchanger (5), the sewage pipe (29) of the tail gas air cooler (16) and the sewage pipe (52) of the flue gas waste heat recovery unit (37) are all connected to the inlet of the condensate separation and recovery device (57). The condensate separation and recovery device (57) is used to collect the condensate precipitated during the heat exchange and cooling process of each stage, and to perform liquid-liquid separation on the condensate to extract and recover ethylene glycol components. The intelligent collaborative control unit includes a multi-parameter sensor network and an edge computing controller. The multi-parameter sensor network includes temperature sensors and pressure sensors installed on each pipe of the exhaust gas treatment unit and the waste heat cascade utilization unit. The edge computing controller is communicatively connected to the multi-parameter sensor network and electrically connected to the control valves and fans installed in the exhaust gas treatment unit and the waste heat cascade utilization unit. It is used to dynamically adjust the opening degree of the control valves and the speed of the fans according to the real-time sensor data collected by the multi-parameter sensor network.

[0006] Furthermore, the multi-parameter sensing network specifically includes: Low-temperature rich liquid inlet temperature sensor (2) and low-temperature rich liquid inlet pressure sensor (3) are installed on the low-temperature rich liquid inlet pipe (1). A rich liquid flow meter (6) and a low-temperature rich liquid outlet temperature sensor (7) are installed on the low-temperature rich liquid outlet pipe (8). The exhaust gas inlet temperature sensor (10) and exhaust gas inlet pressure sensor (11) are installed on the exhaust gas inlet pipe (9). The exhaust gas intermediate temperature sensor (13) is installed on the exhaust gas intermediate pipe (14). A high-temperature rich liquid inlet temperature sensor (34) and a high-temperature rich liquid inlet pressure sensor (35) are installed on the high-temperature rich liquid inlet pipe (33). A high-temperature rich liquid outlet temperature sensor (38) is installed on the high-temperature rich liquid outlet pipe (39). A flue gas inlet temperature sensor (43) and a flue gas inlet pressure sensor (44) are installed on the flue gas inlet pipe (42). A flue gas outlet temperature sensor (46) is installed on the flue gas outlet pipe (49).

[0007] Furthermore, the exhaust end of the exhaust gas air cooler (16) is also connected to an exhaust gas outlet pipe (21). The multi-parameter sensing network also includes an exhaust outlet temperature sensor (19) and an exhaust outlet pressure sensor (20) disposed on the exhaust outlet pipe (21).

[0008] Furthermore, the control valve specifically includes: The exhaust gas inlet valve (12) is installed on the exhaust gas inlet pipe (9). A one-way valve (15) for exhaust gas is installed on the exhaust gas intermediate pipe (14). The high-temperature rich liquid inlet valve (36) is installed on the high-temperature rich liquid inlet pipe (33). A flue gas inlet valve (45) is installed on the flue gas inlet pipe (42); The flue gas outlet valve (48) is installed on the flue gas outlet pipe (49).

[0009] Furthermore, the exhaust gas treatment unit also includes: The exhaust gas air cooler bypass pipe (22) is connected at both ends to the exhaust gas intermediate pipe (14) and the exhaust gas outlet pipe (21), respectively, and the exhaust gas air cooler bypass valve (23) is installed on the exhaust gas air cooler bypass pipe (22). A bypass pipe (25) for a gas-rich tubular heat exchanger, which connects the exhaust gas inlet pipe (9) and the exhaust gas intermediate pipe (14) at both ends, and a bypass valve (24) for a gas-rich tubular heat exchanger installed on the bypass pipe (25).

[0010] Furthermore, the waste heat cascade utilization unit also includes: A high-temperature rich liquid bypass pipe (41) with its two ends connected to the high-temperature rich liquid inlet pipe (33) and the high-temperature rich liquid outlet pipe (39) respectively, and a high-temperature rich liquid bypass valve (40) installed on the high-temperature rich liquid bypass pipe (41). A flue gas bypass pipe (50) with its two ends connected to the flue gas inlet pipe (42) and the flue gas outlet pipe (49) respectively, and a flue gas bypass valve (51) installed on the flue gas bypass pipe (50).

[0011] Furthermore, the exhaust gas-rich liquid tubular heat exchanger (5) is provided with a low-temperature rich liquid exhaust port (4) that connects to the drainage pipe (27), and the drainage pipe (27) is provided with an exhaust gas-rich liquid tubular heat exchanger drain valve (26). The sewage pipe (29) is equipped with a tail gas air cooler drain valve (30). The sewage pipe (52) is equipped with a flue gas waste heat recovery device sewage valve (53); A device drain valve (28) is provided between the condensate separation and recovery device (57) and the tail gas-rich tubular heat exchanger drain valve (26). The rich liquid return end of the exhaust gas-rich liquid tubular heat exchanger (5) is connected to the rich liquid maintenance pipeline (32) of the exhaust gas-rich liquid tubular heat exchanger, and the rich liquid maintenance valve (31) of the exhaust gas-rich liquid tubular heat exchanger is provided on the rich liquid maintenance pipeline (32). The flue gas waste heat recovery device (37) is also provided with a flue gas waste heat recovery device pipeline maintenance pipe (54), and a flue gas waste heat recovery device maintenance valve (55) is provided on the flue gas waste heat recovery device pipeline maintenance pipe (54). A maintenance port main valve (56) is provided at the total outlet end after the rich liquid maintenance pipeline (32) of the exhaust gas-rich liquid tubular heat exchanger and the flue gas waste heat recovery device pipeline maintenance pipeline (54) merge.

[0012] Furthermore, the exhaust gas air cooler (16) is a variable frequency exhaust gas air cooler, and the exhaust gas air cooler (16) is equipped with exhaust gas air cooler No. 1 fan (17) and exhaust gas air cooler No. 2 fan (18). A high-temperature flue gas induced draft fan (47) is also installed on the flue gas outlet pipe (49) between the flue gas outlet valve (48) and the flue gas outlet temperature sensor (46).

[0013] Furthermore, the edge computing controller has a built-in operating condition identification model and energy consumption optimization algorithm for executing: When the flue gas temperature is detected by the flue gas inlet temperature sensor (43) to be lower than the preset condensation threshold, the flue gas inlet valve (45) is closed and the flue gas bypass valve (51) is opened, so that the flue gas passes through the flue gas bypass pipe (50) to prevent condensation corrosion of the waste heat recovery unit. When the water content in the exhaust gas is assessed to be higher than the preset ratio based on the monitoring data of the exhaust gas inlet temperature sensor (10) and the exhaust gas inlet pressure sensor (11), the opening of the exhaust gas inlet valve (12) and the exhaust gas-rich tubular heat exchanger bypass valve (24) is dynamically adjusted so that part of the exhaust gas passes through the exhaust gas-rich tubular heat exchanger bypass pipe (25) for bypass pretreatment.

[0014] Furthermore, the condensate separation and recovery device (57) integrates a centrifugal separation module and a membrane filtration module to perform liquid-liquid separation on the condensate; The waste liquid outlet of the condensate separation and recovery device (57) is connected to an integrated sewage treatment device to filter and disinfect the wastewater after the separation of ethylene glycol.

[0015] The beneficial effects of this invention are as follows: This invention abandons the traditional high-energy-consuming direct combustion of exhaust gas. Through the coordinated operation of the exhaust gas treatment unit and the waste heat cascade utilization unit, the low-grade waste heat of the exhaust gas and the high-temperature flue gas waste heat of the reboiler are recovered in stages to preheat the ethylene glycol-rich liquid, which significantly reduces the heating energy consumption and gas consumption of the reboiler. At the same time, the integrated condensate recovery unit realizes the efficient separation and recycling of ethylene glycol components, effectively avoiding the environmental risks of loss of high-value reagents and wastewater discharge. In addition, the intelligent collaborative control unit can dynamically control the valves and heat exchange equipment of each pipeline in real time based on multi-dimensional sensor data, ensuring that the system adaptively maintains the optimal energy-saving operation state under complex conditions such as fluctuations in pipeline gas quality. Finally, relying on the skid-mounted integrated structure, a seamless upgrade of the existing dehydration process system is achieved. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the natural gas condensation dehydration tail gas treatment and residual energy cascade recovery system of the present invention.

[0017] In the attached diagram, the components are: 1. Low-temperature rich liquid inlet pipe; 2. Low-temperature rich liquid inlet temperature sensor; 3. Low-temperature rich liquid inlet pressure sensor; 4. Low-temperature rich liquid exhaust port; 5. Exhaust gas-rich liquid tubular heat exchanger; 6. Rich liquid flow meter; 7. Low-temperature rich liquid outlet temperature sensor; 8. Low-temperature rich liquid outlet pipe; 9. Exhaust gas inlet pipe; 10. Exhaust gas inlet temperature sensor; 11. Exhaust gas inlet pressure sensor; 12. Exhaust gas inlet valve; 13. Exhaust gas intermediate temperature sensor; 14. Exhaust gas intermediate pipe; 15. Exhaust gas check valve; and 16. Exhaust gas air cooler. 16. Exhaust gas air cooler No. 1 fan; 17. Exhaust gas air cooler No. 2 fan; 18. Exhaust gas outlet temperature sensor; 19. Exhaust gas outlet pressure sensor; 20. Exhaust gas outlet pipe; 21. Exhaust gas air cooler bypass pipe; 22. Exhaust gas air cooler bypass valve; 23. Exhaust gas-rich tubular heat exchanger bypass valve; 24. Exhaust gas-rich tubular heat exchanger bypass pipe; 25. Exhaust gas-rich tubular heat exchanger drain valve; 26. Exhaust gas-rich tubular heat exchanger drain pipe; 27. Unit drain valve; 28. Exhaust gas air cooler drain valve. Pipeline 29, Exhaust gas air cooler drain valve; 30, Exhaust gas-rich liquid tubular heat exchanger rich liquid maintenance valve; 31, Exhaust gas-rich liquid tubular heat exchanger rich liquid maintenance pipeline; 32, High-temperature rich liquid inlet pipeline; 33, High-temperature rich liquid inlet temperature sensor; 34, High-temperature rich liquid inlet pressure sensor; 35, High-temperature rich liquid inlet valve; 36, Flue gas waste heat recovery unit; 37, High-temperature rich liquid outlet temperature sensor; 38, High-temperature rich liquid outlet pipeline; 39, High-temperature rich liquid bypass valve; 40, High-temperature rich liquid bypass pipeline; 41, Flue gas inlet pipeline; 4 2. Flue gas inlet temperature sensor 43. Flue gas inlet pressure sensor 44. Flue gas inlet valve 45. Flue gas outlet temperature sensor 46. High-temperature flue gas induced draft fan 47. Flue gas outlet valve 48. Flue gas outlet pipe 49. Flue gas bypass pipe 50. Flue gas bypass valve 51. Flue gas waste heat recovery unit drain pipe 52. Flue gas waste heat recovery unit drain valve 53. Flue gas waste heat recovery unit pipe maintenance pipe 54. Flue gas waste heat recovery unit maintenance valve 55. Main valve for maintenance port 56. Condensate separation and recovery device 57.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] To address the high energy consumption of the combustion exhaust gas in the natural gas condensation dehydration process and the significant energy waste during the reboiler heating of ethylene glycol-rich liquid, this invention discloses a natural gas condensation dehydration exhaust gas treatment and waste energy recovery system, applicable to energy-saving upgrades of various scales of natural gas condensation dehydration units. This skid-mounted integrated system comprises an exhaust gas treatment unit and a waste energy recovery unit, allowing for flexible integration into existing dehydration processes. The exhaust gas treatment unit utilizes low-temperature rich liquid and air as a cold source to condense and separate the high-moisture-content exhaust gas. The separated combustible gas can be recovered as fuel, replacing or reducing the energy consumption of the combustion exhaust gas. The waste energy recovery unit recovers the waste heat from the reboiler combustion exhaust gas through a flue gas waste heat recovery unit, which is then used to heat the ethylene glycol-rich liquid, reducing reboiler fuel consumption. This invention eliminates the high energy consumption of traditional combustion exhaust gas in a combustion furnace, achieving resource utilization of exhaust gas and waste heat recovery, significantly reducing energy consumption and pollutant emissions in the natural gas condensation dehydration process. It meets the energy-saving needs of oil and gas production and has broad application prospects.

[0021] like Figure 1 As shown, the present invention provides a natural gas condensation dehydration tail gas treatment and waste heat cascade recovery system, including a tail gas treatment unit, a waste heat cascade utilization unit, a condensate recovery unit and an intelligent collaborative control unit. The exhaust gas treatment unit includes an exhaust gas-rich liquid tubular heat exchanger 5 and an exhaust gas air cooler 16 connected in sequence by pipelines. The exhaust gas-rich liquid tubular heat exchanger 5 is provided with an exhaust gas inlet pipe 9, an exhaust gas intermediate pipe 14, a low-temperature rich liquid inlet pipe 1, and a low-temperature rich liquid outlet pipe 8. The water-containing exhaust gas discharged from the external natural gas dehydration process enters the exhaust gas-rich liquid tubular heat exchanger 5 through the exhaust gas inlet pipe 9 and exchanges heat with the ethylene glycol rich liquid entering through the low-temperature rich liquid inlet pipe 1 to perform the first stage of cooling on the water-containing exhaust gas. The air inlet of the exhaust gas air cooler 16 is connected to the exhaust gas intermediate pipe 14 and is used to perform the second stage of cooling on the exhaust gas after the first stage of cooling. The waste heat utilization unit includes a flue gas waste heat recovery unit 37; the flue gas waste heat recovery unit 37 is provided with a flue gas inlet pipe 42, a flue gas outlet pipe 49, a high-temperature rich liquid inlet pipe 33, and a high-temperature rich liquid outlet pipe 39; the high-temperature rich liquid inlet pipe 33 is connected to the low-temperature rich liquid outlet pipe 8; the flue gas inlet pipe 42 is used to introduce high-temperature flue gas generated by an external reboiler; the high-temperature flue gas exchanges heat with the ethylene glycol rich liquid flowing in after absorbing heat from the tail gas treatment unit, so as to perform stepped heating of the ethylene glycol rich liquid; the flue gas outlet pipe 49 is used to discharge the flue gas after heat exchange and cooling; the high-temperature rich liquid outlet pipe 39 is used to output the ethylene glycol rich liquid that has completed stepped heating to the reboiler. The condensate recovery unit includes a condensate separation and recovery device 57; the drain pipe 27 of the tail gas-rich tubular heat exchanger 5, the sewage pipe 29 of the tail gas air cooler 16, and the sewage pipe 52 of the flue gas waste heat recovery device 37 are all connected to the inlet of the condensate separation and recovery device 57. The condensate separation and recovery device 57 is used to collect the condensate precipitated during the heat exchange and cooling process of each stage, and to perform liquid-liquid separation on the condensate to extract and recover ethylene glycol components. The intelligent collaborative control unit includes a multi-parameter sensor network and an edge computing controller. The multi-parameter sensor network includes temperature sensors and pressure sensors installed on each pipe of the exhaust gas treatment unit and the waste heat cascade utilization unit. The edge computing controller is communicatively connected to the multi-parameter sensor network and electrically connected to the control valves and fans installed in the exhaust gas treatment unit and the waste heat cascade utilization unit. It is used to dynamically adjust the opening degree of the control valves and the speed of the fans according to the real-time sensor data collected by the multi-parameter sensor network.

[0022] In this embodiment, the intelligent collaborative control unit, based on multi-dimensional sensor data and process models, uses intelligent algorithms to achieve dynamic adaptation and precise control of each stage of exhaust gas treatment and waste energy recovery. The system deploys a comprehensive data acquisition system, including exhaust gas temperature sensors, rich liquid temperature sensors, and sensors monitoring CO2 and NO. x The unit incorporates a flue gas composition sensor to measure emissions, and integrates it with existing temperature and pressure sensors to construct a multi-parameter sensor network. At its core is an edge computing controller with a built-in operating condition recognition model and energy consumption optimization algorithm. This controller can analyze parameters such as flue gas temperature and rich liquid flow rate in real time, automatically adjusting valve opening, fan speed, and heat exchanger status. For example, when the exhaust gas moisture content exceeds 30%, it automatically switches part of the flow back to the pretreatment stage, or opens a bypass channel to prevent condensation and corrosion when the flue gas temperature is below 80°C. Furthermore, the unit includes a remote monitoring and maintenance module, supporting real-time visualization of operating status, fault warnings, and remote parameter adjustments, effectively reducing maintenance costs.

[0023] The exhaust gas treatment unit achieves deep optimization of exhaust gas treatment through a newly added two-stage condensation mechanism. The first stage utilizes low-temperature rich liquid for deep cooling, while the second stage uses a variable frequency exhaust gas air cooler for precise temperature control. Regarding condensate recovery, the system adds a condensate separation and recovery device to the sewage pipeline, employing centrifugal separation and membrane filtration technology to achieve a recovery rate of over 95% for organic components such as ethylene glycol in the condensate. The recovered ethylene glycol is returned to the MEG buffer tank for recycling through a dedicated pipeline, while the remaining wastewater enters the on-site sewage treatment plant for treatment before discharge, significantly reducing environmental pollution and resource waste. The exhaust gas treatment unit and the waste energy recovery unit are mutually compatible, achieving energy-saving and carbon-reduction goals without affecting the original dehydration process.

[0024] The waste heat recovery unit constructs a highly efficient tiered recovery system to reduce energy consumption in the regeneration process. The primary waste heat recovery stage targets the intermittent exhaust gas from the regeneration of ethylene glycol rich liquor, utilizing the heat from the over-90°C saturated water vapor it carries to raise the temperature of the rich liquor and replace the original electric or steam heat tracing system for providing heat to the rich liquor pipeline. The secondary waste heat recovery stage uses a flue gas waste heat recovery unit to raise the preheating temperature of the ethylene glycol rich liquor from 50°C to 80°C using high-temperature flue gas exceeding 150°C, directly reducing the heating energy consumption of the reboiler. Furthermore, a high-efficiency dust removal and desulfurization module is added before the flue gas outlet, capable of removing over 90% of dust and SO2 from the flue gas. The entire unit adopts a skid-mounted integrated design, allowing for flexible integration or disengagement during the operation of existing dehydration units, ensuring process flexibility and environmental compliance.

[0025] The core principle of the condensate recovery unit is to efficiently recover the liquid generated during the exhaust gas condensation process through physical separation, thereby solving the resource waste and environmental pressure caused by centralized condensate discharge. In the key process, the condensate is collected through the discharge outlet and first enters the separator for preliminary treatment. The separated wastewater then enters the integrated wastewater treatment unit, where it is treated by filtration and disinfection to meet industrial reuse standards. This treated reclaimed water can be directly used for daily cleaning of the unit or on-site greening irrigation, forming a resource closed loop from "treatment-recovery" to "reuse," further improving the system's resource efficiency.

[0026] In one embodiment, the multi-parameter sensing network specifically includes: a low-temperature rich liquid inlet temperature sensor 2 and a low-temperature rich liquid inlet pressure sensor 3 disposed on the low-temperature rich liquid inlet pipe 1; a rich liquid flow meter 6 and a low-temperature rich liquid outlet temperature sensor 7 disposed on the low-temperature rich liquid outlet pipe 8; an exhaust gas inlet temperature sensor 10 and an exhaust gas inlet pressure sensor 11 disposed on the exhaust gas inlet pipe 9; an exhaust gas intermediate temperature sensor 13 disposed on the exhaust gas intermediate pipe 14; a high-temperature rich liquid inlet temperature sensor 34 and a high-temperature rich liquid inlet pressure sensor 35 disposed on the high-temperature rich liquid inlet pipe 33; a high-temperature rich liquid outlet temperature sensor 38 disposed on the high-temperature rich liquid outlet pipe 39; a flue gas inlet temperature sensor 43 and a flue gas inlet pressure sensor 44 disposed on the flue gas inlet pipe 42; and a flue gas outlet temperature sensor 46 disposed on the flue gas outlet pipe 49.

[0027] In this embodiment, by densely deploying high-precision monitoring probes on various key pipelines, including setting a low-temperature rich liquid inlet temperature sensor 2 and a low-temperature rich liquid inlet pressure sensor 3 on the low-temperature rich liquid inlet pipeline 1, setting a rich liquid flow meter 6 and a low-temperature rich liquid outlet temperature sensor 7 on the low-temperature rich liquid outlet pipeline 8, and arranging corresponding temperature sensors 10, 13, 34, 38, 43, 46 and pressure sensors 11, 35, 44 on the exhaust gas inlet pipeline 9, the exhaust gas intermediate pipeline 14, the high-temperature rich liquid inlet pipeline 33, the high-temperature rich liquid outlet pipeline 39, the flue gas inlet pipeline 42, and the flue gas outlet pipeline 49, a comprehensive and dead-angle-free real-time thermodynamic and dynamic condition monitoring network can be constructed for the system.

[0028] In one embodiment, the exhaust end of the exhaust gas air cooler 16 is also connected to an exhaust gas outlet pipe 21; the multi-parameter sensing network further includes an exhaust gas outlet temperature sensor 19 and an exhaust gas outlet pressure sensor 20 disposed on the exhaust gas outlet pipe 21.

[0029] In this embodiment, by connecting the exhaust end of the exhaust gas air cooler 16 to the exhaust gas outlet pipe 21, and connecting the exhaust gas outlet pipe 21 to the flue gas inlet pipe 42, the treated exhaust gas and the high-temperature flue gas pipeline are structurally combined. At the same time, an exhaust gas outlet temperature sensor 19 and an exhaust gas outlet pressure sensor 20 are added to the exhaust gas outlet pipe 21, further improving the data monitoring system for the final state of exhaust gas emission, so that the system can grasp the physical property parameters of the final discharged gas.

[0030] In one embodiment, the control valves specifically include: an exhaust gas inlet valve 12 disposed on the exhaust gas inlet pipe 9; an exhaust gas check valve 15 disposed on the exhaust gas intermediate pipe 14; a high-temperature rich liquid inlet valve 36 disposed on the high-temperature rich liquid inlet pipe 33; a flue gas inlet valve 45 disposed on the flue gas inlet pipe 42; and a flue gas outlet valve 48 disposed on the flue gas outlet pipe 49.

[0031] In this embodiment, by configuring tail gas inlet valve 12, tail gas check valve 15, high temperature rich liquid inlet valve 36, flue gas inlet valve 45 and flue gas outlet valve 48 on tail gas inlet pipe 9, tail gas intermediate pipe 14, high temperature rich liquid inlet pipe 33, flue gas inlet pipe 42 and flue gas outlet pipe 49 respectively, a physical execution terminal is provided for the background control algorithm to accurately cut off the fluid or adjust the flow of each material, ensuring the controllability of process start-up and shutdown and flow allocation.

[0032] In one embodiment, the exhaust gas treatment unit further includes: an exhaust gas air cooler bypass pipe 22 with both ends connected to the exhaust gas intermediate pipe 14 and the exhaust gas outlet pipe 21, and an exhaust gas air cooler bypass valve 23 disposed on the exhaust gas air cooler bypass pipe 22; an exhaust gas-rich liquid tube heat exchanger bypass pipe 25 with both ends connected to the exhaust gas inlet pipe 9 and the exhaust gas intermediate pipe 14, and an exhaust gas-rich liquid tube heat exchanger bypass valve 24 disposed on the exhaust gas-rich liquid tube heat exchanger bypass pipe 25.

[0033] In this embodiment, by setting the exhaust gas air cooler bypass pipe 22 and its exhaust gas air cooler bypass valve 23 in parallel, and the exhaust gas-rich tube heat exchanger bypass pipe 25 and its exhaust gas-rich tube heat exchanger bypass valve 24, the system can flexibly divert the exhaust gas direction when facing sudden changes in flow or when it needs to adjust the condensing load, avoiding damage or failure of the core heat exchange equipment due to overload, and building a safe defense and adaptive adjustment channel for the exhaust gas treatment unit.

[0034] In one embodiment, the waste heat cascade utilization unit further includes: a high-temperature rich liquid bypass pipe 41 with its two ends connected to the high-temperature rich liquid inlet pipe 33 and the high-temperature rich liquid outlet pipe 39 respectively, and a high-temperature rich liquid bypass valve 40 disposed on the high-temperature rich liquid bypass pipe 41; a flue gas bypass pipe 50 with its two ends connected to the flue gas inlet pipe 42 and the flue gas outlet pipe 49 respectively, and a flue gas bypass valve 51 disposed on the flue gas bypass pipe 50.

[0035] In this embodiment, by adding a high-temperature rich liquid bypass pipe 41 and its high-temperature rich liquid bypass valve 40, as well as a flue gas bypass pipe 50 and its flue gas bypass valve 51, when the temperature of the flue gas discharged from the reboiler is abnormal or the flow rate of the rich liquid fluctuates significantly, the high-temperature or low-temperature materials can be quickly diverted through the bypass channel, thereby preventing the heat exchanger from being damaged due to extreme temperature difference stress, ensuring the operational stability of the system's heat exchange process, and providing the necessary flow distribution and equipment protection mechanism for the waste heat cascade utilization unit.

[0036] In one embodiment, the exhaust gas-rich liquid tubular heat exchanger 5 is provided with a low-temperature rich liquid exhaust port 4 connected to the drainage pipe 27; the drainage pipe 27 is provided with an exhaust gas-rich liquid tubular heat exchanger drain valve 26; the sewage pipe 29 is provided with an exhaust gas air cooler drain valve 30; the sewage pipe 52 is provided with a flue gas waste heat recovery device drain valve 53; a device drain valve 28 is provided between the condensate separation and recovery device 57 and the exhaust gas-rich liquid tubular heat exchanger drain valve 26; the rich liquid return end of the exhaust gas-rich liquid tubular heat exchanger 5 is connected to... The exhaust gas-rich liquid tubular heat exchanger has a rich liquid maintenance pipeline 32, on which a rich liquid maintenance valve 31 is installed; the flue gas waste heat recovery unit 37 also has a flue gas waste heat recovery unit pipeline maintenance pipeline 54, on which a flue gas waste heat recovery unit maintenance valve 55 is installed; and a maintenance port main valve 56 is provided at the total outlet end after the exhaust gas-rich liquid tubular heat exchanger rich liquid maintenance pipeline 32 and the flue gas waste heat recovery unit pipeline maintenance pipeline 54 merge.

[0037] In this embodiment, by configuring the low-temperature rich liquid exhaust port 4, the tail gas-rich liquid tubular heat exchanger drain valve 26, the tail gas air cooler drain valve 30, the flue gas waste heat recovery unit drain valve 53, and the device drain valve 28 at relevant nodes, it is ensured that the condensate precipitated by cooling can be smoothly introduced into the condensate separation and recovery device 57; at the same time, in conjunction with the tail gas-rich liquid tubular heat exchanger rich liquid maintenance pipeline 32 and the tail gas-rich liquid tubular heat exchanger rich liquid maintenance valve 31, the flue gas waste heat recovery unit pipeline maintenance pipeline 54 and the flue gas waste heat recovery unit maintenance valve 55, and the maintenance port main valve 56, the equipment venting efficiency and the safety of shutdown maintenance are greatly improved, and the system's daily drainage and shutdown maintenance network is improved.

[0038] In one embodiment, the exhaust gas air cooler 16 is a variable frequency exhaust gas air cooler, and the exhaust gas air cooler 16 is equipped with exhaust gas air cooler No. 1 fan 17 and exhaust gas air cooler No. 2 fan 18; a high temperature flue gas induced draft fan 47 is also installed on the flue gas outlet pipe 49 between the flue gas outlet valve 48 and the flue gas outlet temperature sensor 46.

[0039] In this embodiment, a frequency converter-controlled exhaust gas air cooler 16 is used, and exhaust gas air cooler No. 1 fan 17 and exhaust gas air cooler No. 2 fan 18 are built in, realizing dynamic energy-saving adjustment of air cooling intensity; and a high-temperature flue gas induced draft fan 47 is added between the flue gas outlet valve 48 and the flue gas outlet temperature sensor 46 in the flue gas outlet pipe 49, which effectively overcomes the resistance of flue gas in the flow and heat exchange process inside the pipe, ensuring that the exhaust gas can be forcibly drawn out and maintaining a good pressure balance inside the system.

[0040] In one embodiment, the edge computing controller has a built-in operating condition identification model and energy consumption optimization algorithm, used to perform the following: when the flue gas temperature is detected by the flue gas inlet temperature sensor 43 to be lower than the preset condensation threshold, the controller closes the flue gas inlet valve 45 and opens the flue gas bypass valve 51, so that the flue gas passes through the flue gas bypass pipe 50 to prevent condensation corrosion of the waste heat recovery unit; when the water content in the exhaust gas is assessed to be higher than the preset ratio based on the monitoring data of the exhaust gas inlet temperature sensor 10 and the exhaust gas inlet pressure sensor 11, the controller dynamically adjusts the opening of the exhaust gas inlet valve 12 and the exhaust gas-rich tubular heat exchanger bypass valve 24, so that part of the exhaust gas passes through the exhaust gas-rich tubular heat exchanger bypass pipe 25 for bypass pretreatment.

[0041] In this embodiment, when the flue gas inlet temperature sensor 43 detects that the temperature is too low, it will close the flue gas inlet valve 45 and open the flue gas bypass valve 51 to allow the exhaust gas to flow through the flue gas bypass pipe 50 to completely prevent low-temperature dew point corrosion of the waste heat recovery equipment. When the exhaust gas inlet temperature sensor 10 and the exhaust gas inlet pressure sensor 11 determine that the moisture content of the exhaust gas exceeds the standard, the exhaust gas inlet valve 12 and the exhaust gas-rich liquid tube heat exchanger bypass valve 24 will be adjusted to divert part of the exhaust gas through the exhaust gas-rich liquid tube heat exchanger bypass pipe 25, ensuring the condensation and dehydration efficiency and stable operation of the whole machine.

[0042] In one embodiment, the condensate separation and recovery device 57 integrates a centrifugal separation module and a membrane filtration module to perform liquid-liquid separation of the condensate; the waste liquid outlet of the condensate separation and recovery device 57 is connected to an integrated sewage treatment device to filter and disinfect the wastewater after the separation of ethylene glycol.

[0043] In this embodiment, it is clarified that the condensate separation and recovery device 57 uses the internally integrated centrifugal separation module and membrane filtration module to perform efficient liquid-liquid physical separation of the collected condensate, and directly connects its waste liquid discharge outlet to the integrated sewage treatment device, forming a complete environmentally friendly disposal process chain that recycles and utilizes high-value ethylene glycol in a closed loop and filters and disinfects residual wastewater to meet standards.

[0044] The overall workflow of this invention is as follows: The low-temperature ethylene glycol-rich liquid from the external natural gas dehydration process first enters the tail gas-rich liquid tubular heat exchanger 5, where it undergoes a first-stage heat exchange with the high-moisture-content tail gas to absorb its waste heat. Subsequently, the pre-heated rich liquid flows into the flue gas waste heat recovery unit 37, where it undergoes a second-stage deep heat exchange with the high-temperature flue gas generated by the external reboiler. After two stages of heating, the high-temperature rich liquid is finally output to the reboiler, thus significantly reducing the original heating fuel consumption of the reboiler.

[0045] While preheating the rich liquid, the system performs two-stage cooling on the water-containing exhaust gas discharged from the rich liquid regeneration. The high-moisture-content exhaust gas first has its heat removed by the low-temperature rich liquid in the exhaust gas-rich liquid tubular heat exchanger 5, completing the first stage of cooling and condensation. Next, the cooled exhaust gas enters the exhaust gas air cooler 16, where it undergoes a second stage of cooling under the action of exhaust gas air cooler fan 17 and exhaust gas air cooler fan 18. After two stages of condensation and separation, the moisture and recombinant gases in the exhaust gas are separated, and the remaining combustible gases are recovered as fuel, thereby replacing or reducing the energy consumption of the combustion furnace.

[0046] The system centrally collects and purifies the waste liquid released during the cooling process of heat exchange equipment at all levels. The drainage pipe 27 of the exhaust gas-rich tubular heat exchanger 5, the sewage pipe 29 of the exhaust gas air cooler 16, and the sewage pipe 52 of the flue gas waste heat recovery unit 37 are all connected to the inlet of the condensate separation and recovery device 57. The condensate separation and recovery device 57 uses its internal centrifugal separation and membrane filtration modules to separate the collected condensate into liquid and extract and recover ethylene glycol. The wastewater after the ethylene glycol separation is discharged into an integrated wastewater treatment device for subsequent filtration and disinfection.

[0047] Throughout the entire physical workflow, the edge computing controller ensures dynamic safety and adaptive operation. The edge computing controller acquires real-time data on pipe temperature, pressure, and other parameters from a multi-parameter sensor network, dynamically adjusting the opening of control valves and fan speed. When the flue gas temperature sensor 43 detects that the flue gas temperature is below the preset condensation threshold, the controller opens the flue gas bypass valve 51 to allow the flue gas to flow through the flue gas bypass pipe 50, preventing condensation and corrosion of the flue gas waste heat recovery unit 37. When the exhaust gas moisture content is assessed to be too high, the controller dynamically adjusts the exhaust gas inlet valve 12 and the exhaust gas-rich tubular heat exchanger bypass valve 24, allowing a portion of the exhaust gas to flow through the exhaust gas-rich tubular heat exchanger bypass pipe 25 for bypass pretreatment.

[0048] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0049] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A natural gas condensate dehydration tail gas treatment and residual energy cascade recovery system, characterized in that, It includes an exhaust gas treatment unit, a waste heat cascade utilization unit, a condensate recovery unit, and an intelligent collaborative control unit; The exhaust gas treatment unit includes an exhaust gas-rich liquid tubular heat exchanger (5) and an exhaust gas air cooler (16) connected in sequence by pipelines. The exhaust gas-rich liquid tubular heat exchanger (5) is provided with an exhaust gas inlet pipe (9), an exhaust gas intermediate pipe (14), a low-temperature rich liquid inlet pipe (1), and a low-temperature rich liquid outlet pipe (8). The water-containing exhaust gas discharged from the external natural gas dehydration process enters the exhaust gas-rich liquid tubular heat exchanger (5) through the exhaust gas inlet pipe (9) and exchanges heat with the ethylene glycol rich liquid entering through the low-temperature rich liquid inlet pipe (1) to perform the first stage of cooling on the water-containing exhaust gas. The air inlet of the exhaust gas air cooler (16) is connected to the exhaust gas intermediate pipe (14) and is used to perform the second stage of cooling on the exhaust gas after the first stage of cooling. The waste heat utilization unit includes a flue gas waste heat recovery unit (37); the flue gas waste heat recovery unit (37) is provided with a flue gas inlet pipe (42), a flue gas outlet pipe (49), a high-temperature rich liquid inlet pipe (33), and a high-temperature rich liquid outlet pipe (39); the high-temperature rich liquid inlet pipe (33) is connected to the low-temperature rich liquid outlet pipe (8); the flue gas inlet pipe (42) is used to introduce high-temperature flue gas generated by an external reboiler; the high-temperature flue gas exchanges heat with the ethylene glycol rich liquid that flows in after absorbing heat from the tail gas treatment unit, so as to perform stepped heating of the ethylene glycol rich liquid; the flue gas outlet pipe (49) is used to discharge the flue gas after heat exchange and cooling; the high-temperature rich liquid outlet pipe (39) is used to output the ethylene glycol rich liquid that has completed stepped heating to the reboiler. The condensate recovery unit includes a condensate separation and recovery device (57); the drain pipe (27) of the tail gas-rich tubular heat exchanger (5), the sewage pipe (29) of the tail gas air cooler (16) and the sewage pipe (52) of the flue gas waste heat recovery unit (37) are all connected to the inlet of the condensate separation and recovery device (57). The condensate separation and recovery device (57) is used to collect the condensate precipitated during the heat exchange and cooling process of each stage, and to perform liquid-liquid separation on the condensate to extract and recover ethylene glycol components. The intelligent collaborative control unit includes a multi-parameter sensor network and an edge computing controller. The multi-parameter sensor network includes temperature sensors and pressure sensors installed on each pipe of the exhaust gas treatment unit and the waste heat cascade utilization unit. The edge computing controller is communicatively connected to the multi-parameter sensor network and electrically connected to the control valves and fans installed in the exhaust gas treatment unit and the waste heat cascade utilization unit. It is used to dynamically adjust the opening degree of the control valves and the speed of the fans according to the real-time sensor data collected by the multi-parameter sensor network.

2. The natural gas condensate dehydration tail gas treatment and surplus energy cascade recovery system according to claim 1, characterized in that, The multi-parameter sensing network specifically includes: Low-temperature rich liquid inlet temperature sensor (2) and low-temperature rich liquid inlet pressure sensor (3) are installed on the low-temperature rich liquid inlet pipe (1). A rich liquid flow meter (6) and a low-temperature rich liquid outlet temperature sensor (7) are installed on the low-temperature rich liquid outlet pipe (8). The exhaust gas inlet temperature sensor (10) and exhaust gas inlet pressure sensor (11) are installed on the exhaust gas inlet pipe (9). The exhaust gas intermediate temperature sensor (13) is installed on the exhaust gas intermediate pipe (14). A high-temperature rich liquid inlet temperature sensor (34) and a high-temperature rich liquid inlet pressure sensor (35) are installed on the high-temperature rich liquid inlet pipe (33). A high-temperature rich liquid outlet temperature sensor (38) is installed on the high-temperature rich liquid outlet pipe (39). A flue gas inlet temperature sensor (43) and a flue gas inlet pressure sensor (44) are installed on the flue gas inlet pipe (42). A flue gas outlet temperature sensor (46) is installed on the flue gas outlet pipe (49).

3. The natural gas condensed dehydration tail gas treatment and residual energy cascade recovery system according to claim 2, characterized in that, The exhaust end of the exhaust gas air cooler (16) is also connected to an exhaust gas outlet pipe (21). The multi-parameter sensing network also includes an exhaust outlet temperature sensor (19) and an exhaust outlet pressure sensor (20) disposed on the exhaust outlet pipe (21).

4. The natural gas condensed dehydration tail gas treatment and residual energy cascade recovery system according to claim 3, characterized in that, The control valve specifically includes: The exhaust gas inlet valve (12) is installed on the exhaust gas inlet pipe (9). A one-way valve (15) for exhaust gas is installed on the exhaust gas intermediate pipe (14). The high-temperature rich liquid inlet valve (36) is installed on the high-temperature rich liquid inlet pipe (33). A flue gas inlet valve (45) is installed on the flue gas inlet pipe (42); The flue gas outlet valve (48) is installed on the flue gas outlet pipe (49).

5. The natural gas condensed dehydration tail gas treatment and residual energy cascade recovery system according to claim 4, characterized in that, The exhaust gas treatment unit further includes: The exhaust gas air cooler bypass pipe (22) is connected at both ends to the exhaust gas intermediate pipe (14) and the exhaust gas outlet pipe (21), respectively, and the exhaust gas air cooler bypass valve (23) is installed on the exhaust gas air cooler bypass pipe (22). A bypass pipe (25) for a gas-rich tubular heat exchanger, which connects the exhaust gas inlet pipe (9) and the exhaust gas intermediate pipe (14) at both ends, and a bypass valve (24) for a gas-rich tubular heat exchanger installed on the bypass pipe (25).

6. The natural gas condensed dehydration tail gas treatment and surplus energy cascade recovery system according to claim 5, characterized in that, The waste heat cascade utilization unit also includes: A high-temperature rich liquid bypass pipe (41) with its two ends connected to the high-temperature rich liquid inlet pipe (33) and the high-temperature rich liquid outlet pipe (39) respectively, and a high-temperature rich liquid bypass valve (40) installed on the high-temperature rich liquid bypass pipe (41). A flue gas bypass pipe (50) with its two ends connected to the flue gas inlet pipe (42) and the flue gas outlet pipe (49) respectively, and a flue gas bypass valve (51) installed on the flue gas bypass pipe (50).

7. The natural gas condensation dehydration tail gas treatment and waste energy cascade recovery system according to claim 1, characterized in that, The exhaust gas-rich liquid tubular heat exchanger (5) is provided with a low-temperature rich liquid exhaust port (4) that connects to the drainage pipe (27), and the drainage pipe (27) is provided with an exhaust gas-rich liquid tubular heat exchanger steam trap (26). The sewage pipe (29) is equipped with a tail gas air cooler drain valve (30). The sewage pipe (52) is equipped with a flue gas waste heat recovery device sewage valve (53); A device drain valve (28) is provided between the condensate separation and recovery device (57) and the tail gas-rich tubular heat exchanger drain valve (26). The rich liquid return end of the exhaust gas-rich liquid tubular heat exchanger (5) is connected to the rich liquid maintenance pipeline (32) of the exhaust gas-rich liquid tubular heat exchanger, and the rich liquid maintenance valve (31) of the exhaust gas-rich liquid tubular heat exchanger is provided on the rich liquid maintenance pipeline (32). The flue gas waste heat recovery device (37) is also provided with a flue gas waste heat recovery device pipeline maintenance pipe (54), and a flue gas waste heat recovery device maintenance valve (55) is provided on the flue gas waste heat recovery device pipeline maintenance pipe (54). A maintenance port main valve (56) is provided at the total outlet end after the rich liquid maintenance pipeline (32) of the exhaust gas-rich liquid tubular heat exchanger and the flue gas waste heat recovery device pipeline maintenance pipeline (54) merge.

8. The natural gas condensate dehydration tail gas treatment and surplus energy cascade recovery system according to claim 4, characterized in that, The exhaust air cooler (16) is a variable frequency exhaust air cooler, and the exhaust air cooler (16) is equipped with exhaust air cooler No. 1 fan (17) and exhaust air cooler No. 2 fan (18). A high-temperature flue gas induced draft fan (47) is also installed on the flue gas outlet pipe (49) between the flue gas outlet valve (48) and the flue gas outlet temperature sensor (46).

9. The natural gas condensate dehydration tail gas treatment and surplus energy cascade recovery system according to claim 6, characterized in that, The edge computing controller has a built-in operating condition identification model and energy consumption optimization algorithm for execution: When the flue gas temperature is detected by the flue gas inlet temperature sensor (43) to be lower than the preset condensation threshold, the flue gas inlet valve (45) is closed and the flue gas bypass valve (51) is opened, so that the flue gas passes through the flue gas bypass pipe (50) to prevent condensation corrosion of the waste heat recovery unit. When the water content in the exhaust gas is assessed to be higher than the preset ratio based on the monitoring data of the exhaust gas inlet temperature sensor (10) and the exhaust gas inlet pressure sensor (11), the opening of the exhaust gas inlet valve (12) and the exhaust gas-rich tubular heat exchanger bypass valve (24) is dynamically adjusted so that part of the exhaust gas passes through the exhaust gas-rich tubular heat exchanger bypass pipe (25) for bypass pretreatment.

10. The natural gas condensation dehydration tail gas treatment and waste energy cascade recovery system according to claim 1, characterized in that, The condensate separation and recovery device (57) integrates a centrifugal separation module and a membrane filtration module to perform liquid-liquid separation on the condensate. The waste liquid outlet of the condensate separation and recovery device (57) is connected to an integrated sewage treatment device to filter and disinfect the wastewater after the separation of ethylene glycol.

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