Unattended geothermal heating tail water recharge system automatic control process

Abstract

The present application belongs to the field of geothermal heating, and relates to an unattended geothermal heating tail water recharge system automatic control process. Geothermal tail water is filtered by a multi-stage filtering module, and the filtered tail water is recharged to the ground after being pressurized by a pressurizing module. The multi-stage filtering module automatically backwashes, and the automatic backwashing function is automatically started by differential pressure or filtering time. The pressurizing module intelligently and automatically operates, and has intelligent control programs such as automatic start of the pressurizing pump, automatic frequency conversion, automatic increase of the number of pressurizing pumps, automatic reduction of the number of pressurizing pumps, automatic pump stop, and linkage of the pressurizing pump outlet valve when the pump starts and stops. The present application solves the problems and defects of low intelligent degree, poor adaptability, insufficient execution response accuracy, weak signal transmission anti-interference ability, and low safety in the automatic control of the existing recharge system, realizes intelligent and automatic control operation of the geothermal tail water recharge system in large-scale production, and reaches the level of unattended operation.

Description

Technical Field

[0001] This invention belongs to the field of geothermal heating, specifically relating to an automated control process for an unattended geothermal heating tailwater reinjection system. Background Technology

[0002] Geothermal energy, as a clean and renewable green energy source, is highly favored by the heating industry, and geothermal heating has become the first choice for the industry's energy-saving and low-carbon transformation. However, due to the characteristics of geothermal resources, development and utilization must meet the basic requirement of 100% reinjection of geothermal tailwater, making geothermal tailwater reinjection a core challenge in geothermal heating. Because geothermal water exists in different geological conditions, its quality varies greatly, often containing sand particles and suspended solids of different sizes. Geothermal tailwater reinjection systems require multiple technical steps, including multi-stage filtration, backwashing, and pressurized reinjection. Problems in any of these steps will lead to system interruption, and failure to address them promptly can cause serious accidents. Therefore, the automatic control technology of geothermal tailwater reinjection systems is particularly important and is key to ensuring the safe and stable operation of geothermal heating projects. Currently, existing technologies or products only design automatic control for certain parts of the reinjection system, but cannot achieve the expected intelligent control and unattended operation of the entire reinjection system. This not only results in high operating costs but also poses safety hazards.

[0003] For example, the invention patent "Sandstone Geothermal Tailwater Economic Reinjection System" (publication number CN103816714A) has an automatic adjustment device designed in only two locations. One is an automatic control valve designed between the booster pump and the reinjection well. Specifically, when the pressure in the reinjection well is too high and reinjection cannot proceed, the opening of the automatic control valve is adjusted to drain water and relieve pressure. The other is an automatic frequency adjustment design for the booster pump. Specifically, when the geothermal tailwater volume in the reinjection system is large, the booster pump frequency is increased to increase the reinjection volume and reduce the system pressure. When the geothermal tailwater volume decreases, the booster pump frequency is reduced to decrease the reinjection volume to prevent the booster pump from running dry. The overall level of automation of this invention is low, and there are still obvious deficiencies and defects, as follows: (1) The system does not have an automatic start-stop function for the booster pump. If the well is damaged or the pipeline bursts, resulting in a small or no flow of water in the reinjection system, the booster pump cannot be shut down in time, which can easily cause the booster pump to run dry and burn out the motor. Secondly, when the system is restarted, the booster pump cannot be started automatically and needs to be started manually; (2) The system does not have an automatic backwashing process. Although a backup filter is designed, there is no automatic control switching between the main filter and the backup filter. If the main filter becomes clogged and the inspection personnel do not handle it in time, it will cause the system to pressurize, leading to pipe bursts or water overflows; (3) The system does not have an automatic pressure relief program designed at the front end of the filter. If the filter becomes clogged and pressurized, it is easy to cause pipe bursts or water overflows; (4) In this system, except for the drain valve between the booster pump and the reinjection well which has an automatic adjustment function, the other valves are not designed with an automatic adjustment function, and the degree of self-control is too low; (5) The self-control process of the whole system is not perfect and cannot reach the level of intelligent control without human intervention. The human participation is too high and it is not suitable for actual operating conditions.

[0004] For example, in comparison with the utility model patent "A geothermal reinjection filtration device" (publication number: CN210814158U), it only mentions that some valves are electrically connected, but does not specify the automatic control technology or process, and basically does not design an automatic control program, so it does not reach the level of intelligent automatic control.

[0005] For example, compared with the utility model patent "A Sandstone-type Thermal Storage Geothermal Heating Reinjection System" (Publication No.: CN221172369U), the system only has automatic control for filter backwashing and pressure relief protection. The degree of automatic control is also low. The main shortcomings are: (1) It does not have the function of automatically increasing or decreasing the frequency of the booster pump with changes in water volume and pressure; (2) It does not have the function of automatically starting or stopping the booster pump with changes in system flow and pressure; (3) It does not have the function of automatically increasing or decreasing the number of booster pumps with the increase or decrease of tailwater volume; (4) It cannot realize the valve linkage function between the booster pump and the reinjection well; (5) The system cannot automatically adjust the parameters according to the actual situation and cannot achieve unattended operation. Summary of the Invention

[0006] This invention provides an unattended automatic control process for geothermal heating tailwater reinjection systems. The purpose is to solve the problems and defects in the automatic control of existing reinjection systems, such as low level of intelligence, poor adaptability, insufficient execution response accuracy, weak signal transmission anti-interference ability, and low security. The invention aims to achieve intelligent automatic control operation of geothermal tailwater reinjection systems in large-scale production, reaching the level of unattended operation, reducing the labor intensity of human workers, and improving the safety of reinjection systems in heating projects.

[0007] Therefore, the present invention adopts the following technical solution: An automated control process for an unattended geothermal heating tailwater reinjection system, characterized by comprising a reinjection well, a multi-stage filtration module, a pressurization module, and a power distribution control module; Multiple reinjection wells are deployed according to the site conditions. Each reinjection well works independently and the geothermal tailwater is reinjected into the ground through the reinjection well. The geothermal tailwater is filtered by a multi-stage filtration module. After being pressurized by a pressurization module, the filtered tailwater is reinjected into the ground through the reinjection well. Each reinjection well is equipped with at least one independent pressurization pump. Automatic backwashing operation of multi-stage filtration modules: The multi-stage filtration module includes a coarse filtration module, a medium filtration module, and a fine filtration module connected in sequence. Multiple sets of coarse filtration modules are connected in parallel, and each coarse filtration module is equipped with a backwashing structure. The backwashing function is automatically activated based on the pressure difference value or the running time of the coarse filtration module. When one coarse filtration module is backwashed, the other coarse filtration modules continue to operate normally. Multiple sets of medium filtration modules and fine filtration modules are also connected in parallel, and they are also equipped with backwashing structures. The backwashing function is automatically activated based on the pressure difference value or the running time of the filtration modules, so that the multi-stage filtration module is automatically cleaned to meet the requirements of long-term stable filtration. Automatic start-up and frequency adjustment of the pressurization module: The pressurization module includes pressurization pumps and inlet and outlet water pipes. Each pressurization pump is connected in parallel to the main inlet water pipe, which is equipped with a pressure sensor. Each pressurization pump outlet is connected to its corresponding reinjection well via a sealed pipe, and each pressurization pump outlet is equipped with a linked pneumatic valve. Independent pressure sensors and flow meters are installed on the connecting pipes. Parameters include: pump start-up pressure limit, pump stop-down pressure value, normal pressure range, pump start-up sequence, number of pumps started, initial pump start-up frequency, maximum operating frequency of the pressurization pump, minimum operating frequency of the pressurization pump, start-stop interval time of the pressurization pump, and frequency increase / decrease interval time of the pressurization pump. As the geothermal tailwater volume continuously increases, the system pressure rises to... When the pump start-up pressure condition is met, the first booster pump starts. After starting, if the system geothermal tailwater pressure continues to increase and exceeds the upper limit of the normal pressure range, the frequency of the first booster pump is increased first. When the system pressure drops to the normal pressure range, the pump maintains the same frequency. If the system geothermal tailwater pressure is still greater than the upper limit of the normal pressure range after increasing the frequency to the maximum frequency, the second booster pump is automatically started, and so on, increasing the frequency first and then increasing the number of pumps. If the system heating tailwater pressure decreases, the frequency is reduced first. If the pressure still decreases after reducing to the lowest frequency, the pump is stopped, and so on. When increasing the number of pumps, they are started in the set start-up sequence. When stopping the pumps, they are stopped in reverse order of the start-up sequence, with the last pump started stopping first and the first pump started stopping last. The power distribution control module includes a main power distribution cabinet, a booster pump frequency converter cabinet, a main control cabinet, an air compressor, and an air storage tank. The main control cabinet is used to control the automatic backwashing operation of the multi-stage filtration module, the automatic start-up and frequency adjustment of the booster module, and the on / off control of all pneumatic valves.

[0008] Furthermore, the inlet / outlet and backwash outlet of the coarse filtration module are equipped with pneumatic control valves, the inlet of each coarse filtration module is equipped with an inlet pressure sensor, and the main outlet pipe of the coarse filtration module is equipped with an outlet pressure sensor; each sensor and control valve is connected to the CPU of the coarse filtration module via a 485 signal control line, and the CPU is then connected to the main control cabinet via a dedicated line. The intermediate filtration module and the fine filtration module are equipped with pneumatic control valves, inlet water pressure sensors, and outlet water pressure sensors with the same functions, as well as a CPU dedicated to the intermediate filtration module and a CPU dedicated to the fine filtration module. They are then connected to the main control cabinet via dedicated lines. The backwashing function of the multi-stage filtration module is activated when the pressure difference monitored by the pressure sensor at the inlet / outlet is triggered by a threshold; or a threshold is set for the continuous filtration time of the multi-stage filtration module, and the backwashing function is activated when the pressure difference is not reached but the filtration time reaches the threshold. The backwashing function is automatically activated by judging the dual conditions.

[0009] Furthermore, the backwashing structure of the intermediate filter module and the fine filter module is also equipped with a high-pressure air inlet and a special device. When the backwashing function is turned on, high-pressure water is introduced at the same time as high-pressure air, and backwashing is carried out through air-water mixing.

[0010] Furthermore, at least two pressure sensors are installed on the main inlet pipe of the pressurization module; when the pressure values ​​of any two of the two pressure sensors on the main inlet pipe of the pressurization module and the one main outlet pressure sensor of the fine filtration module reach the set pump start pressure limit, the pressurization pump will start automatically; by judging the combined values ​​of multiple pressure sensors, the safety and accuracy of the automatic start and frequency regulation operation of the pressurization module are improved.

[0011] Furthermore, a pneumatic valve is installed between the booster pump and the reinjection well. When the booster pump needs to be started, the corresponding pneumatic valve opens automatically first, and the booster pump starts after the valve opens. When the booster pump needs to be stopped, the pump stops first, and the pneumatic valve closes automatically after the booster pump stops completely. This prevents the high-pressure water in the reinjection well from flowing back and causing erosion to the booster pump, multi-stage filtration module equipment, and other equipment after the booster pump stops.

[0012] Furthermore, the main inlet of the reinjection system is equipped with a bypass valve and a bypass pipe. If the pressure value monitored by 30-50% of the inlet pressure sensors of the coarse filter module exceeds the safety threshold, the bypass valve and bypass pipe will be activated for emergency pressure relief, and an alarm will be issued at the same time.

[0013] Furthermore, the ratio of the number of coarse filtration modules, medium filtration modules and fine filtration modules is 3:(1.5-2):(1.5-2), wherein the number of medium filtration modules is not less than the number of fine filtration modules.

[0014] The applications of this invention are as follows: 1. This invention is based on a three-stage geothermal tailwater reinjection system, taking a scale of 6 reinjection wells as an example, to illustrate the technical solution of this invention. This invention subdivides the geothermal tailwater reinjection system into a coarse filtration module, a medium filtration module, a fine filtration module, a pressurization module, and a power distribution and control module. Specifically, the coarse filtration module consists of 6 coarse filters connected in parallel, with the total effluent from the coarse filtration module connected to the total inlet of the medium filtration module via a pipeline; the medium filtration module consists of 4 medium filters connected in parallel, with the total effluent from the medium filtration module connected to the total inlet of the fine filtration module via a pipeline; the fine filtration module consists of 4 fine filters connected in parallel, with the total effluent from the fine filtration module connected to the total inlet of the pressurization module via a pipeline; the pressurization module consists of 6 pressurization pumps connected in parallel, each pressurization pump connected to a corresponding reinjection well via a pipeline; the power distribution and control module consists of a main power distribution cabinet, a pressurization pump frequency converter cabinet, a PLC main control cabinet, an air compressor, and an air storage tank, among other equipment.

[0015] 2. This invention adopts an independent PLC central control system, which uses 485 signal transmission to monitor the pressure sensors, temperature sensors and other instruments in each module of the entire reinjection system and control the opening and closing of all valves. Then, through an automatic control program, it realizes the monitoring of the operating status and automatic operation control of the entire reinjection system.

[0016] 3. In this invention, pneumatic control valves are installed at the inlet and outlet of the six coarse filters connected in parallel within the coarse filtration module, as well as at the backwash outlet. An independent inlet pressure sensor is installed at the inlet of each filter, and an outlet pressure sensor is installed on the main outlet pipe of each coarse filtration module. Each sensor and control valve is connected to a dedicated CPU within the coarse filtration module via a 485 signal control line, and this CPU is then connected to a PLC control cabinet via a dedicated line. During normal operation, the inlet and outlet valves of all six coarse filters automatically open, while the backwash outlet valve remains closed. If, during operation, the difference between the inlet pressure of any coarse filter and the total outlet pressure of its corresponding coarse filtration module (where the inlet pressure is greater than the outlet pressure, creating a pressure difference) reaches a preset limit, or the continuous filtration time of the filter reaches a preset limit, then that coarse filter will enter automatic backwash mode. At this point, the inlet valve of the coarse filter automatically closes, and the backwash outlet valve automatically opens. The geothermal water, filtered by other coarse filters, backwashes the coarse filter, removing suspended solids and large particles of silt, thus ensuring its filtration performance. Once the backwashing process reaches a preset duration, the backwashing mode of the coarse filter ends, its inlet valve automatically opens, and the backwash outlet valve automatically closes, returning it to normal operation. This process achieves intelligent, fully automated operation of the coarse filtration module.

[0017] 4. This invention equips the inlet and outlet ports, high-pressure air inlet, and backwash outlet of the four parallel medium / fine filter modules with pneumatic control valves. Each medium / fine filter inlet is equipped with an independent inlet pressure sensor, and a total outlet pressure sensor is installed on the main outlet pipe of the medium / fine filter module. All sensors and valves are connected to the dedicated CPU of the medium / fine filter module via a 485 signal control line, and the CPU is then connected to the PLC control cabinet via a dedicated line. During normal operation, the inlet and outlet valves of the four medium / fine filters are automatically open, while the high-pressure air inlet valve and backwash outlet valve are closed. If, during operation, the difference between the inlet pressure of any medium / fine filter and the corresponding total outlet pressure of the medium / fine filter module (the pressure difference is greater than the outlet pressure) reaches a preset limit, or the continuous filtration time of the filter reaches a preset limit, then that medium / fine filter will enter automatic backwash mode. When the medium / fine filter enters backwash mode, its inlet valve automatically closes, while the high-pressure air inlet valve and backwash outlet valve automatically open. Water filtered by other medium / fine filters and high-pressure gas simultaneously enter the medium / fine filter, performing high-pressure air-water mixed backwashing to efficiently remove fine sediment particles adhering to the filter element. Once the backwashing process reaches a preset duration, the backwashing mode of the medium / fine filter ends, its inlet valve automatically opens, and the high-pressure air inlet valve and backwash outlet valve automatically close, returning to normal operation. This process achieves intelligent, fully automated operation of the medium / fine filtration module.

[0018] 5. This invention includes two pressure sensors (to prevent program execution errors due to single sensor failure) and one temperature sensor installed in the main inlet pipe of the pressurization module. The inlets of six parallel pressurization pumps are connected to the main inlet pipe via pipelines. Pneumatic valves are installed at the outlets of each pump, connecting them to the corresponding reinjection wells. Pressure sensors are installed on the connecting pipelines. Each sensor and valve is connected to the pressurization module's dedicated CPU via a 485 signal control line, and the CPU is then connected to the PLC control cabinet via a dedicated line. The frequency converter starter of each pressurization pump is connected to the PLC control cabinet via a dedicated line, enabling automatic control of the pressurization pumps. During normal operation, the outlet valve of the pressurization pump automatically closes. Parameters such as the pump start-up pressure limit, pump stop pressure, normal pressure range, pump start-up sequence, number of pumps started, initial pump start-up frequency, maximum operating frequency, minimum operating frequency, start-stop interval, and frequency adjustment interval are set for the pressurization pumps. As the volume of filtered geothermal tailwater increases, the system pressure also increases. In the booster pump, among the two inlet total pressure sensors and the fine filtration module's one outlet total pressure sensor, the booster pump automatically starts when the pressure values ​​of any two sensors reach the set start-up pressure limit. The booster pumps start sequentially according to the set start-up order and the maximum number of pumps that can be started. First, the first booster pump starts automatically at the initial start-up frequency. If, within the set booster pump frequency increase / decrease interval, the pressure values ​​of any two of the three pressure sensors are still higher than the set normal pressure upper limit, the first booster pump will automatically increase its frequency to reduce the system pressure. If the pressure values ​​of any two of the three pressure sensors drop to within the set normal pressure range, the booster pump maintains this frequency for stable operation. If, as the geothermal tailwater volume increases, the first booster pump reaches the set maximum operating frequency, and the pressure values ​​of any two of the three pressure sensors are still higher than the set normal pressure upper limit, reaching the booster pump start / stop interval, the second booster pump will automatically start to reduce the system operating pressure, and its operating frequency will be consistent with the first pump. When two booster pumps are running simultaneously, if the pressure values ​​of any two of the three pressure sensors remain within the normal pressure range, the two booster pumps will maintain stable operation at this frequency. If the pressure values ​​of any two of the three pressure sensors drop below the lower limit of the normal pressure range, the two booster pumps will simultaneously reduce their frequency according to the set interval between booster pump frequency increases to keep the system pressure within the normal pressure range. If, as the geothermal tailwater volume continues to increase, the two activated booster pumps increase their frequency to the set maximum operating frequency according to the set interval between booster pump frequency increases, and if the pressure values ​​of any two of the three pressure sensors are still higher than the set upper limit of the normal pressure, and the start / stop interval of the booster pumps is reached, then the third booster pump will be automatically started in sequence, and so on... When the local thermal tailwater volume decreases, the filter is backwashed, or the system automatically depressurizes, causing a drop in system pressure, if the pressure values ​​of any two of the three pressure sensors drop below the lower limit of the set normal pressure range, the system will prioritize reducing the frequency of the multiple booster pumps that have already started, based on the interval between the booster pumps' rise and fall frequencies, to maintain the system pressure within the normal pressure range. If the frequency of the multiple booster pumps that have already started has been reduced to the set minimum operating frequency, but the pressure values ​​of any two of the three pressure sensors are still below the lower limit of the set normal pressure range, the system will execute a pump reduction procedure, prioritizing the shutdown of the last booster pump that was started. After pump reduction, the remaining booster pumps automatically adjust their frequencies according to the aforementioned frequency increase / decrease procedure to maintain the system pressure within the normal pressure range. If the geothermal tailwater volume continues to decrease or the system pressure continues to drop after the well pump is shut down, the remaining booster pumps will first automatically reduce their frequencies to the minimum operating frequency according to the aforementioned frequency increase / decrease procedure. If, after frequency reduction, the pressure values ​​of any two of the three pressure sensors are still lower than the set lower limit of the normal pressure range, the system will intelligently determine and execute pump reduction—frequency adjustment—pump reduction according to the aforementioned procedure until the last booster pump is reduced. At this time, the pump will not immediately stop due to operating at the minimum operating frequency, but will maintain low-frequency operation to protect system safety. The last booster pump will only stop when the pressure values ​​of any two of the three pressure sensors are lower than the set stop pressure value. This automatic control technology can fully realize the intelligent and fully automatic operation of the system pressurization module, and can automatically start and stop pumps and automatically increase / decrease frequencies.

[0019] The core logic is as follows: After the first booster pump starts, when the system pressure increases, the frequency is increased first. If the system pressure is still higher than the upper limit of the safe pressure range after the frequency is increased to the maximum frequency, the second booster pump is automatically started, and so on, increasing the frequency first and then starting the pump. When the system pressure decreases, the frequency is decreased first and then the pump is stopped, and so on. When adding pumps, they are started sequentially according to the set start-up order, and when stopping pumps, they are stopped in reverse order of start-up, with the last pump started stopping first and the first pump started stopping last.

[0020] The beneficial effects of this invention are as follows: 1. The entire reinjection system can be fully automated through PLC program control. Based on actual operating conditions, the system automatically executes procedures such as normal filtration / backwashing of each stage of the filter module, automatic pump start-up, automatic frequency adjustment, automatic pump addition / reduction, automatic pump shutdown, and automatic pressure relief alarm in emergencies. This achieves unattended operation and significantly improves the safety of the system's automated operation.

[0021] 2. The automatic start-up, automatic frequency conversion, and automatic pump shutdown procedures of the pressurization module's pressurization pump, as well as the execution of the system's emergency pressure relief procedure, all utilize data from multiple sensors for comprehensive judgment. This effectively avoids erroneous operations caused by abnormal data from a single sensor, and significantly improves the accuracy of the system's automatic operation.

[0022] 3. This invention incorporates a pneumatic valve between the booster pump and the reinjection well. When a booster pump needs to be started, the corresponding pneumatic valve automatically opens, and the booster pump starts accordingly. When a booster pump needs to be stopped, it stops first, and the pneumatic valve automatically closes after the booster pump has completely stopped. This automated control process effectively solves the problem of high-pressure water backflow from the reinjection well causing erosion to the booster pump and filter after the booster pump stops.

[0023] 4. This invention incorporates a bypass valve and bypass pipe at the main inlet of the reinjection system. If the sensor readings of the inlet pressure of three or more of the six parallel coarse filters in the reinjection system exceed the set maximum system pressure, it indicates a blockage in the reinjection system requiring emergency pressure relief. In this case, the main inlet bypass valve automatically opens, simultaneously triggering the emergency alarm system to send an alarm signal to inspection personnel, enabling timely repairs and enhancing emergency response capabilities to maximize system safety.

[0024] 5. Each module of this invention is equipped with an independent CPU, which avoids the complicated process of connecting each sensor and valve signal control line in the system to the PLC control cabinet. Each module's signal is aggregated by its own CPU and then transmitted to the PLC control system in a unified manner, reducing the wiring cost of the entire reinjection system. Most importantly, it solves the problem of interference between signal transmission lines in the entire system and solves the problems of slow sensor and valve signal transmission and slow response.

[0025] 6. The PLC automatic control program in this invention is designed with both automatic and manual operating modes. In automatic mode, the entire system operates automatically, automatically filtering, backwashing, starting the pump, adjusting the frequency, adding or removing pumps, and stopping the pump according to specific operating conditions. Backwash water is automatically circulated, and an emergency pressure relief alarm is activated, all without manual intervention. In manual mode, all valves can be manually switched on and off, and the status and values ​​of instruments, sensors, and valves can be displayed via the touchscreen on the PLC control panel. Furthermore, this invention includes emergency switch buttons for all valves in automatic mode. In special circumstances, a valve can still be manually controlled in emergency situations without affecting the normal operation of the entire system. The entire system's automatic control program is flexible, adaptable, and can meet various operating conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the automatic control process of an unattended geothermal heating tailwater reinjection system according to the present invention.

[0027] In the diagram: 1. Bypass valve; 2. First pressure gauge; 3. First pneumatic valve; 4. First automatic air release valve; 5. Second pneumatic valve; 6. Second pressure gauge; 7. First coarse filter; 8. Third pneumatic valve; 9. Fourth pneumatic valve; 10. Second automatic air release valve; 11. Third pressure gauge; 12. Fifth pneumatic valve; 13. Second coarse filter; 14. Sixth pneumatic valve; 15. Fourth pressure gauge; 16. Fifth pressure gauge; 17. Seventh pneumatic valve; 18. Third automatic air release valve; 19. Sixth pressure gauge; 20. Eighth pneumatic valve; 21. Third coarse filter; 22. Ninth pneumatic valve 23. Tenth pneumatic valve; 24. Fourth automatic air release valve; 25. Seventh pressure gauge; 26. Eleventh pneumatic valve; 27. Fourth coarse filter; 28. Twelfth pneumatic valve; 29. ​​Eighth pressure gauge; 30. Ninth pressure gauge; 31. Thirteenth pneumatic valve; 32. Fifth automatic air release valve; 33. Tenth pressure gauge; 34. Fourteenth pneumatic valve; 35. Fifth coarse filter; 36. Fifteenth pneumatic valve; 37. Sixteenth pneumatic valve; 38. Sixth automatic air release valve; 39. Eleventh pressure gauge; 40. Seventeenth pneumatic valve; 41. Sixth coarse filter; 42. Eighteenth pneumatic valve 43. Twelfth pressure gauge; 44. First intermediate filter; 45. Nineteenth pneumatic valve; 46. Twentieth pneumatic valve; 47. Twenty-first pneumatic valve; 48. Twenty-second pneumatic valve; 49. Seventh automatic air release valve; 50. Thirteenth pressure gauge; 51. Twenty-third pneumatic valve; 52. Twenty-fourth pneumatic valve; 53. Twenty-fifth pneumatic valve; 54. Second intermediate filter; 55. Fourteenth pressure gauge; 56. Eighth automatic air release valve; 57. Twenty-sixth pneumatic valve; 58. Twenty-seventh pneumatic valve; 59. Twenty-eighth pneumatic valve; 60. Third intermediate filter; 61. Fifteenth Pressure gauge; 62. Ninth automatic air release valve; 63. Twenty-ninth pneumatic valve; 64. Thirtieth pneumatic valve; 65. Thirty-first pneumatic valve; 66. Thirty-second pneumatic valve; 67. Fourth intermediate filter; 68. Sixteenth pressure gauge; 69. Tenth automatic air release valve; 70. Thirty-third pneumatic valve; 71. Thirty-fourth pneumatic valve; 72. Seventeenth pressure gauge; 73. First fine filter; 74. Thirty-fifth pneumatic valve; 75. Thirty-sixth pneumatic valve; 76. Eighteenth pressure gauge; 77. Eleventh automatic air release valve; 78. Thirty-seventh pneumatic valve; 79. Thirty-eighth pneumatic valve; 80. Thirty-ninth pneumatic valve; 81. Fortieth pneumatic valve; 82. Second fine filter; 83. Nineteenth pressure gauge; 84. Twelfth automatic air release valve; 85. Forty-first pneumatic valve; 86. Forty-second pneumatic valve; 87. Forty-third pneumatic valve; 88. Forty-fourth pneumatic valve; 89. Third fine filter; 90. Twentieth pressure gauge; 91. Thirteenth automatic air release valve; 92. Forty-fifth pneumatic valve; 93. Forty-sixth pneumatic valve; 94.95. Pneumatic Valve No. 47; 96. Pneumatic Valve No. 48; 97. Fourth Fine Filter; 98. Pressure Gauge No. 21; 99. Automatic Air Release Valve No. 14; 100. Pneumatic Valve No. 49; 101. Pneumatic Valve No. 50; 102. Pressure Gauge No. 22; 103. Automatic Air Release Valve No. 15; 104. Pressure Gauge No. 24; 105. Temperature Transmitter; 106. First Variable Frequency Booster Pump; 107. Pneumatic Valve No. 51; 108. Pressure Gauge No. 25; 109. First Flow Meter; 110. Second Variable Frequency Booster Pump; 111. Pneumatic Valve No. 52; 112. Pressure Gauge No. 26; 113. Second Flow Meter; 114. Third Variable Frequency Booster Pump; 115. Pneumatic Valve No. 53; 116. Pressure Gauge No. 27; 117. Third Flow Meter; 118. Fourth Variable Frequency Booster Pump; 119. Pneumatic Valve No. 54; 1 20. Pressure gauge No. 28; 121. Flow meter No. 4; 122. Variable frequency booster pump No. 5; 123. Pneumatic valve No. 55; 124. Pressure gauge No. 29; 125. Flow meter No. 5; 126. Variable frequency booster pump No. 6; 127. Pneumatic valve No. 56; 128. Pressure gauge No. 30; 129. Flow meter No. 6; 130. Reinjection well No. 1; 131. Reinjection well No. 2; 132. Reinjection well No. 3; 133. Reinjection well No. 4 Wells; 134. Recharge Well No. 5; 135. Recharge Well No. 6; 136. Gas Storage Tank; 137. Air Compressor; 138. Main Distribution Cabinet; 139. Booster Pump Frequency Converter Cabinet; 140. PLC Main Control Cabinet; 141. First Check Valve; 142. CPU Module No. 1; 143. CPU Module No. 2; 144. CPU Module No. 3; 145. CPU Module No. 4; 146. CPU Module No. 5; 147. CPU Module No. 6. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1As shown, an unattended geothermal heating tailwater reinjection system's automatic control process is mainly achieved through the interlocking of control valves and instruments in the coarse filtration module, medium filtration module, fine filtration module, pressurization module, and power distribution control module within the geothermal tailwater reinjection system. The coarse filtration module consists of three coarse filter sub-modules connected in parallel. The first coarse filtration sub-module comprises a first coarse filter 7 and a second coarse filter 13 connected in parallel; the second coarse filtration sub-module comprises a third coarse filter 21 and a fourth coarse filter 27 connected in parallel; and the third coarse filtration sub-module comprises a fifth coarse filter 35 and a sixth coarse filter 41 connected in parallel. The total outlet of the coarse filtration module is connected to the total inlet of the medium filtration module via a pipeline. The medium filtration module consists of a first medium filter 44, a second medium filter 54, a third medium filter 60, and a fourth medium filter 67 connected in parallel. The total outlet of the medium filtration module is connected to the total inlet of the fine filtration module via a pipeline. The fine filtration module... The system consists of a first fine filter 73, a second fine filter 82, a third fine filter 89, and a fourth fine filter 96 connected in parallel. The total water outlet of the fine filtration module is connected to the total water inlet of the pressurization module through a pipeline. The pressurization module consists of a first variable frequency pressurization pump 106, a second variable frequency pressurization pump 110, a third variable frequency pressurization pump 114, a fourth variable frequency pressurization pump 118, a fifth variable frequency pressurization pump 122, and a sixth variable frequency pressurization pump 126 connected in parallel. Each pressurization pump is connected to the corresponding reinjection well through a pipeline. The power distribution control module consists of a main power distribution cabinet 138, a pressurization pump frequency converter cabinet 139, a PLC main control cabinet 140, an air compressor 137, and an air storage tank 136, among other equipment.

[0030] The coarse filtration module consists of three sub-modules connected in parallel. Coarse filtration sub-module 1 comprises a first coarse filter 7 and a second coarse filter 13 connected in parallel. The first coarse filter 7 is equipped with a first automatic air vent valve 4 and a second pressure gauge 6. The inlet of the first coarse filter 7 is connected to the main inlet pipe via a first pneumatic valve 3, and the outlet of the first coarse filter 7 is connected to the main outlet pipe via a third pneumatic valve 8. The backwash drain outlet of the first coarse filter 7 is connected to the main drain pipe via a second pneumatic valve 5. The second coarse filter 13 is equipped with a second automatic air vent valve 10 and a third pressure gauge 11. The inlet of the second coarse filter 13 is connected to the main inlet pipe via a fourth pneumatic valve 9, and the outlet of the second coarse filter 13 is connected to the main outlet pipe via a sixth pneumatic valve 14. The backwash drain outlet of the second coarse filter 13 is connected to the main drain pipe via a fifth pneumatic valve 12. In this module, each pneumatic valve and pressure gauge is connected to a dedicated CPU module 142 via a 485 signal control line. This CPU module is then connected to the PLC main control cabinet 140 via a dedicated line. Specifically, the first pneumatic valve 3, the second pneumatic valve 5, the third pneumatic valve 8, the fourth pneumatic valve 9, the fifth pneumatic valve 12, and the sixth pneumatic valve 14 are interconnected with the second pressure gauge 6, the third pressure gauge 11, and the fourth pressure gauge 15 to open and close the valves, completing the filtration and backwashing operations. The coarse filtration submodule 2 consists of a third coarse filter 21 and a fourth coarse filter 27 connected in parallel. The third coarse filter 21 is equipped with a third automatic air vent valve 18 and a sixth pressure gauge 19. The inlet of the third coarse filter 21 is connected to the main inlet pipe via a seventh pneumatic valve 17, the outlet of the third coarse filter 21 is connected to the main outlet pipe via a ninth pneumatic valve 22, and the backwash drain of the third coarse filter 21 is connected to the main drain pipe via an eighth pneumatic valve 20. The fourth coarse filter 27 is equipped with a fourth automatic air vent valve 24 and a seventh pressure gauge 25. The inlet of the fourth coarse filter 27 is connected to the main inlet pipe via a tenth pneumatic valve 23, and the outlet of the fourth coarse filter 27 is connected to the main outlet pipe via a twelfth pneumatic valve 28. The backwash drain outlet of the fourth coarse filter 27 is connected to the main drain pipe via an eleventh pneumatic valve 26. In this module, each pneumatic valve and pressure gauge is connected to a dedicated CPU module 143 via a 485 signal control line. This CPU module is then connected to the PLC main control cabinet 140 via a dedicated line. The seventh pneumatic valve 17, eighth pneumatic valve 20, ninth pneumatic valve 22, tenth pneumatic valve 23, eleventh pneumatic valve 26, and twelfth pneumatic valve 28 are interconnected with the sixth pressure gauge 19, seventh pressure gauge 25, and eighth pressure gauge 29 to open and close the valves, completing the filtration and backwashing operations.The coarse filter submodule 3 consists of a fifth coarse filter 35 and a sixth coarse filter 41 connected in parallel. The fifth coarse filter 35 is equipped with a fifth automatic air vent valve 32 and a tenth pressure gauge 33. The inlet of the fifth coarse filter 35 is connected to the main inlet pipe via a thirteenth pneumatic valve 31, and the outlet of the fifth coarse filter 35 is connected to the main outlet pipe via a fifteenth pneumatic valve 36. The backwash drain outlet of the fifth coarse filter 35 is connected to the main drain pipe via a fourteenth pneumatic valve 34. The sixth coarse filter 41 is equipped with a sixth automatic air vent valve 38 and an eleventh pressure gauge 39. The inlet of the sixth coarse filter 41 is connected to the main inlet pipe via a sixteenth pneumatic valve 37, and the outlet of the sixth coarse filter 41 is connected to the main outlet pipe via an eighteenth pneumatic valve 42. The backwash drain outlet of the sixth coarse filter 41 is connected to the main drain pipe via a seventeenth pneumatic valve 40. In this module, each pneumatic valve and pressure gauge is connected to a dedicated CPU module 144 (number 3) via a 485 signal control line. This CPU module is then connected to the PLC main control cabinet 140 via a dedicated line. Pneumatic valves 31 (13th), 34 (14th), 36 (15th), 37 (16th), 40 (17th), and 42 (18th) are interconnected with pressure gauges 33 (10th), 39 (11th), and 43 (12th) to open and close the valves, completing the filtration and backwashing operations.

[0031] The main outlet pipe of the coarse filtration module is connected to the main inlet pipe of the medium filtration module. The first intermediate filter 44 is equipped with a seventh automatic air vent valve 49 and a thirteenth pressure gauge 50. The inlet of the first intermediate filter 44 is connected to the main inlet pipe via a twenty-second pneumatic valve 48, the outlet of the first intermediate filter 44 is connected to the main outlet pipe via a twentieth pneumatic valve 46, the air inlet of the first intermediate filter 44 is connected to the main air pipe via a nineteenth pneumatic valve 45, and the backwash drain outlet of the first intermediate filter 44 is connected to the main drainage pipe via a twenty-first pneumatic valve 47. The second intermediate filter 54 is equipped with an eighth automatic air vent valve 56 and a fourteenth pressure gauge 55. The inlet of the second intermediate filter 54 is connected to the main inlet pipe via a twenty-sixth pneumatic valve 57, the outlet of the second intermediate filter 54 is connected to the main outlet pipe via a twenty-fourth pneumatic valve 52, the air inlet of the second intermediate filter 54 is connected to the main air pipe via a twenty-third pneumatic valve 51, and the backwash drain outlet of the second intermediate filter 54 is connected to the main drainage pipe via a twenty-fifth pneumatic valve 53. The third filter 60 is equipped with a fifteenth pressure gauge 61 and a ninth automatic air vent valve 62. The inlet of the third filter 60 is connected to the main water inlet pipe through a twenty-ninth pneumatic valve 63, the outlet of the third filter 60 is connected to the main outlet pipe through a twenty-eighth pneumatic valve 59, the air inlet of the third filter 60 is connected to the main air pipe through a twenty-seventh pneumatic valve 58, and the backwash drain outlet of the third filter 60 is connected to the main drainage pipe through a thirtieth pneumatic valve 64. The fourth filter 67 is equipped with a sixteenth pressure gauge 68 and a tenth automatic air vent valve 69. The inlet of the fourth filter 67 is connected to the main water inlet pipe through a thirty-third pneumatic valve 70, the outlet of the fourth filter 67 is connected to the main outlet pipe through a thirty-second pneumatic valve 66, the air inlet of the fourth filter 67 is connected to the main air pipe through a thirty-first pneumatic valve 65, and the backwash drain outlet of the fourth filter 67 is connected to the main drainage pipe through a thirty-fourth pneumatic valve 71. In the filter module, each pneumatic valve and pressure gauge is connected to the dedicated CPU module 145 of this module via a 485 signal control line. This CPU module is then connected to the PLC main control cabinet 140 via a dedicated line.Among them, the nineteenth pneumatic valve 45, the twentieth pneumatic valve 46, the twenty-first pneumatic valve 47, and the twenty-second pneumatic valve 48 are linked with the thirteenth pressure gauge 50 and the seventeenth pressure gauge 72; the twenty-third pneumatic valve 51, the twenty-fourth pneumatic valve 52, the twenty-fifth pneumatic valve 53, and the twenty-sixth pneumatic valve 57 are linked with the fourteenth pressure gauge 55 and the seventeenth pressure gauge 72; the twenty-seventh pneumatic valve 58, the twenty-eighth pneumatic valve 59, the twenty-ninth pneumatic valve 63, and the thirtieth pneumatic valve 64 are linked with the fifteenth pressure gauge 61 and the seventeenth pressure gauge 72; and the thirty-first pneumatic valve 65, the thirty-second pneumatic valve 66, the thirty-third pneumatic valve 70, and the thirty-fourth pneumatic valve 71 are linked with the sixteenth pressure gauge 68 and the seventeenth pressure gauge 72, thereby realizing the opening and closing of each valve and completing the filtration and backwashing operations.

[0032] The main outlet pipe of the intermediate filtration module is connected to the fine filtration module as the main inlet pipe of the fine filtration module. The fine filtration module has four fine filters connected in parallel. The first fine filter 73 is equipped with an eighteenth pressure gauge 76 and an eleventh automatic air vent valve 77. The inlet of the first fine filter 73 is connected to the main inlet pipe via a thirty-seventh pneumatic valve 78, the outlet of the first fine filter 73 is connected to the main outlet pipe via a thirty-sixth pneumatic valve 75, the air inlet of the first fine filter 73 is connected to the main air pipe via a thirty-fifth pneumatic valve 74, and the backwash drain outlet of the first fine filter 73 is connected to the main drain pipe via a thirty-eighth pneumatic valve 79. The second fine filter... The filter 82 is equipped with a nineteenth pressure gauge 83 and a twelfth automatic air vent valve 84. The inlet of the second fine filter 82 is connected to the main inlet pipe through a forty-first pneumatic valve 85, the outlet of the second fine filter 82 is connected to the main outlet pipe through a fortieth pneumatic valve 81, the air inlet of the second fine filter 82 is connected to the main air pipe through a thirty-ninth pneumatic valve 80, and the backwash drain outlet of the second fine filter 82 is connected to the main drain pipe through a forty-second pneumatic valve 86. The third fine filter 89 is equipped with a twentieth pressure gauge 90 and a thirteenth automatic air vent valve. Valve 91, the inlet of the third fine filter 89 is connected to the main inlet pipe through the forty-fifth pneumatic valve 92, the outlet of the third fine filter 89 is connected to the main outlet pipe through the forty-fourth pneumatic valve 88, the air inlet of the third fine filter 89 is connected to the main air pipe through the forty-third pneumatic valve 87, and the backwash drain of the third fine filter 89 is connected to the main drain pipe through the forty-sixth pneumatic valve 93; the fourth fine filter 96 is equipped with the twenty-first pressure gauge 97 and the fourteenth automatic air vent valve 98, and the inlet of the fourth fine filter 96 is connected to the forty-ninth Pneumatic valve 99 is connected to the main inlet pipe. The outlet of the fourth fine filter 96 is connected to the main outlet pipe through the forty-eighth pneumatic valve 95. The air inlet of the fourth fine filter 96 is connected to the main air pipe through the forty-seventh pneumatic valve 94. The backwash drain of the fourth fine filter 96 is connected to the main drain pipe through the fiftieth pneumatic valve 100. In the fine filter module, each pneumatic valve and pressure gauge is connected to the dedicated CPU module 146 of this module through the 485 signal control line. This CPU module is then connected to the PLC main control cabinet 140 through a dedicated line.Among them, the 35th pneumatic valve 74, the 36th pneumatic valve 75, the 37th pneumatic valve 78, and the 38th pneumatic valve 79 are interconnected with the 18th pressure gauge 76 and the 22nd pressure gauge 101; the 39th pneumatic valve 80, the 40th pneumatic valve 81, the 41st pneumatic valve 85, and the 42nd pneumatic valve 86 are interconnected with the 19th pressure gauge 83 and the 22nd pressure gauge 101; the 43rd pneumatic valve 87, the 44th pneumatic valve 88, the 45th pneumatic valve 92, and the 46th pneumatic valve 93 are interconnected with the 20th pressure gauge 90 and the 22nd pressure gauge 101; the 47th pneumatic valve 94, the 48th pneumatic valve 95, the 49th pneumatic valve 99, and the 50th pneumatic valve 100 are interconnected with the 21st pressure gauge 97 and the 22nd pressure gauge 101, so as to realize the opening and closing of each valve and complete the filtration and backwashing operation.

[0033] The main outlet pipe of the fine filtration module is connected to the main inlet pipe of the pressurization module. The main inlet pipe is equipped with a fifteenth automatic air vent valve 102, a twenty-third pressure gauge 103, a twenty-fourth pressure gauge 104, and a temperature transmitter 105. The six variable frequency booster pumps of the pressurization module are connected in parallel to the main inlet pipe of the pressurization module, each with a power of 55kW. The outlet of the first variable frequency booster pump 106 is connected to the first reinjection well 130, and the connecting pipe is equipped with a 51st pneumatic valve 107, a 25th pressure gauge 108, and a first flow meter 109; the outlet of the second variable frequency booster pump 110 is connected to the second reinjection well 131, and the connecting pipe is equipped with a 52nd pneumatic valve 111, a 26th pressure gauge 112, and a second flow meter 113; the outlet of the third variable frequency booster pump 114 is connected to the third reinjection well 132, and the connecting pipe is equipped with a 53rd pneumatic valve 115, a 27th pressure gauge 116, and a third flow meter 119. 7; The outlet of the fourth variable frequency booster pump 118 is connected to the reinjection well 133, and the connecting pipe is equipped with the fifty-fourth pneumatic valve 119, the twenty-eighth pressure gauge 120, and the fourth flow meter 121; the outlet of the fifth variable frequency booster pump 122 is connected to the reinjection well 134, and the connecting pipe is equipped with the fifty-fifth pneumatic valve 123, the twenty-ninth pressure gauge 124, and the fifth flow meter 125; the outlet of the sixth variable frequency booster pump 126 is connected to the reinjection well 135, and the connecting pipe is equipped with the fifty-sixth pneumatic valve 127, the thirtieth pressure gauge 128, and the sixth flow meter 129. In the booster module, each pneumatic valve, pressure gauge, and flow meter is connected to the dedicated sixth CPU module 147 of this module via a 485 signal control line, and this CPU module is then connected to the PLC main control cabinet 140 via a dedicated line. The start and stop of each variable frequency booster pump and the opening and closing of the corresponding reinjection well valves are linked with the 22nd pressure gauge 101, the 23rd pressure gauge 103 and the 24th pressure gauge 104 to complete the pressurization and reinjection of geothermal water.

[0034] The control module includes an air tank 136, an air compressor 137, a main power distribution cabinet 138, a booster pump frequency converter cabinet 139, and a PLC control cabinet 140. In this system, the main air pipe is connected to the air outlet of the air tank 136, while the air inlet of the air tank 136 is connected to the air compressor 137.

[0035] Working principle: During normal system operation, system operating parameters need to be set. First, the parameters of the variable frequency booster pump must be set in advance, such as: pump start-up pressure limit 0.08MPa, pump stop-down pressure 0.02MPa, pump start-up sequence, number of pumps started, initial pump start-up frequency 35Hz, maximum booster pump operating frequency 45Hz, minimum booster pump operating frequency 28Hz, and booster pump start / stop interval 120s. After setting, switch the system operating mode from manual to automatic. In this mode, the system will automatically start and stop the booster pumps based on the incoming water volume and pressure, adjusting the booster pump operating frequency and number of pumps to always maintain the system pressure within a safe operating range.

[0036] During operation, the first pneumatic valve 3, the third pneumatic valve 8, the fourth pneumatic valve 9, the sixth pneumatic valve 14, the seventh pneumatic valve 17, the ninth pneumatic valve 22, the tenth pneumatic valve 23, the twelfth pneumatic valve 28, the thirteenth pneumatic valve 31, the fifteenth pneumatic valve 36, the sixteenth pneumatic valve 37, and the eighteenth pneumatic valve 42 in the coarse filter module are all in the automatically open state, while the second pneumatic valve 5, the fifth pneumatic valve 12, the eighth pneumatic valve 20, and the eleventh pneumatic valve 26 are in the open state. The fourteenth pneumatic valve 34 and the seventeenth pneumatic valve 40 are in the closed state; in the middle filter module, the twentieth pneumatic valve 46, the twenty-second pneumatic valve 48, the twenty-fourth pneumatic valve 52, the twenty-sixth pneumatic valve 57, the twenty-eighth pneumatic valve 59, the twenty-ninth pneumatic valve 63, the thirty-second pneumatic valve 66, and the thirty-third pneumatic valve 70 are all in the open state, while the nineteenth pneumatic valve 45, the twenty-first pneumatic valve 47, the twenty-third pneumatic valve 51, and the twenty-fifth pneumatic valve... 53. Pneumatic valves 58 (27th), 64 (30th), 65 (31st), and 71 (34th) are closed. In the fine filtration module, pneumatic valves 75 (36th), 78 (37th), 81 (40th), 85 (41st), 88 (44th), 92 (45th), 95 (48th), and 99 (49th) are open, while pneumatic valves 74 (35th), 79 (38th), 80 (39th), 86 (42nd), 87 (43rd), 93 (46th), 94 (47th), and 100 (50th) are closed. In the pressurization module, pneumatic valves 107 (51st), 111 (52nd), 115 (53rd), 119 (54th), 123 (55th), and 127 (56th) are automatically closed.

[0037] During operation, the geothermal tailwater is filtered sequentially through the coarse filtration module, the medium filtration module, and the fine filtration module before entering the pressurization module. As the volume of geothermal tailwater increases, the system pressure also increases. When the pressure values ​​of any two of the twenty-second pressure gauges 101, twenty-third pressure gauges 103, and twenty-fourth pressure gauges 104 reach the set start-up pressure limit of 0.08 MPa, the variable frequency booster pumps will automatically start sequentially according to the pre-set start-up order and the maximum number of pumps to be started. First, when the pressure values ​​of any two reach the set start-up pressure limit of 0.08 MPa, the first variable frequency booster pump 106 will automatically start at the initial start-up frequency. If, within the set 30-second interval between frequency increases and decreases of the booster pump, the pressure values ​​of any two of the twenty-second pressure gauges 101, twenty-third pressure gauges 103, and twenty-fourth pressure gauges 104 are still higher than the set upper limit of normal pressure by 0.2 MPa, the first variable frequency booster pump 106 will automatically increase its frequency to reduce the system pressure. If, at this time, the pressure difference between any two of the three pressure gauges and the fine filter inlet pressure drops to within the set normal pressure range, the first variable frequency booster pump 106 will maintain stable operation at this frequency. If, as the geothermal water volume continues to increase, the first variable frequency booster pump 106 has reached its set maximum operating frequency of 45Hz, and the pressure values ​​of any two of the twenty-second pressure gauges 101, twenty-third pressure gauge 103, and twenty-fourth pressure gauge 104 are still higher than the set upper limit of normal pressure by 0.2MPa, then the second variable frequency booster pump 110 will automatically start to reduce the system operating pressure, and its operating frequency will be consistent with that of the first pump. When both variable frequency booster pumps are running simultaneously, if the pressure values ​​of any two of the three pressure gauges drop to within the set normal pressure range, then both variable frequency booster pumps will maintain this frequency for stable operation. If the pressure values ​​of any two of the three pressure gauges drop to below the lower limit of the normal pressure range of 0.10MPa, then both variable frequency booster pumps will simultaneously reduce their frequency according to the set interval between increases and decreases, so that the system pressure is always maintained within the normal pressure range. If, as the geothermal water volume continues to increase, the first variable frequency booster pump 106 and the second variable frequency booster pump 110 have reached the set maximum operating frequency of 45Hz, and the pressure values ​​of any two of the twenty-second pressure gauge 101, the twenty-third pressure gauge 103, and the twenty-fourth pressure gauge 104 are still higher than the set normal pressure upper limit of 0.2MPa, then the third variable frequency booster pump 114, the fourth variable frequency booster pump 118, the fifth variable frequency booster pump 122, and the sixth variable frequency booster pump 126 will be automatically started in sequence.

[0038] During operation, when the pressure difference between the second pressure gauge 6 and the fourth pressure gauge 15 of the coarse filter module reaches the preset value of 0.1 MPa, or when the continuous filtration time of the first coarse filter 7 reaches the preset limit of 8 hours, the system automatically closes the first pneumatic valve 3 and simultaneously opens the second pneumatic valve 5 to begin backwashing the first coarse filter 7. After the backwashing process lasts for a preset value of 3 minutes, the backwashing mode of the first coarse filter 7 ends, its first pneumatic valve 3 automatically opens, and its second pneumatic valve 5 automatically closes, returning to normal operation. Similarly, when the pressure difference between the third pressure gauge 11 and the fourth pressure gauge 15 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the second coarse filter 13 reaches the preset limit of 8 hours, the system automatically closes the fourth pneumatic valve 9 and simultaneously opens the fifth pneumatic valve 12 to begin backwashing the second coarse filter 13. After the backwashing process lasts for a preset value of 3 minutes, the backwashing mode of the second coarse filter 13 ends, its fourth pneumatic valve 9 automatically opens, and its fifth pneumatic valve 12 automatically closes, returning to normal operation. Similarly, when the pressure difference between the sixth pressure gauge 19 and the eighth pressure gauge 29 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the third coarse filter 21 reaches the preset limit of 8 hours, the system automatically closes the seventh pneumatic valve 17 and simultaneously opens the eighth pneumatic valve 20 to begin backwashing the third coarse filter 21. When the backwashing process lasts for the preset value of 3 minutes, the backwashing mode of the third coarse filter 21 ends, its seventh pneumatic valve 17 automatically opens, and its eighth pneumatic valve 20 automatically closes, returning to normal operation. Similarly, when the pressure difference between the seventh pressure gauge 25 and the eighth pressure gauge 29 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the fourth coarse filter 27 reaches the preset limit of 8 hours, the system automatically closes the tenth pneumatic valve 23 and simultaneously opens the eleventh pneumatic valve 26 to begin backwashing the fourth coarse filter 27. When the backwashing process lasts for a preset 3 minutes, the backwashing mode of the fourth coarse filter 27 ends, its tenth pneumatic valve 23 automatically opens, and its eleventh pneumatic valve 26 automatically closes, returning to normal operation. Similarly, when the pressure difference between the tenth pressure gauge 33 and the twelfth pressure gauge 43 reaches a preset value of 0.1 MPa, or when the continuous filtration time of the fifth coarse filter 35 reaches a preset limit of 8 hours, the system automatically closes the thirteenth pneumatic valve 31 and simultaneously opens the fourteenth pneumatic valve 34 to begin backwashing the fifth coarse filter 35. When the backwashing process lasts for a preset 3 minutes, the backwashing mode of the fifth coarse filter 35 ends, its thirteenth pneumatic valve 31 automatically opens, and its fourteenth pneumatic valve 34 automatically closes, returning to normal operation.Similarly, when the pressure difference between the eleventh pressure gauge 39 and the twelfth pressure gauge 43 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the sixth coarse filter 41 reaches the preset limit of 8 hours, the system automatically closes the sixteenth pneumatic valve 37 and simultaneously opens the seventeenth pneumatic valve 40 to begin backwashing the sixth coarse filter 41. When the backwashing process lasts for the preset value of 3 minutes, the backwashing mode of the sixth coarse filter 41 ends, its sixteenth pneumatic valve 37 automatically opens, and its seventeenth pneumatic valve 40 automatically closes, returning to normal operation.

[0039] During operation, when the pressure difference between the thirteenth pressure gauge 50 and the seventeenth pressure gauge 72 of the intermediate filter module reaches the preset value of 0.1 MPa, or when the continuous filtration time of the first intermediate filter 44 reaches the preset limit of 8 hours, the first intermediate filter 44 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the twenty-second pneumatic valve 48 and automatically opens the nineteenth pneumatic valve 45 and the twenty-first pneumatic valve 47. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the first intermediate filter 44. When the backwashing process lasts for the preset value of 3 minutes, the backwashing mode of the first intermediate filter 44 ends, and it automatically closes the nineteenth pneumatic valve 45 and the twenty-first pneumatic valve 47, and automatically opens the twenty-second pneumatic valve 48, returning to normal operation. When the pressure difference between the fourteenth pressure gauge 55 and the seventeenth pressure gauge 72 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the second intermediate filter 54 reaches the preset limit of 8 hours, the second intermediate filter 54 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the 26th pneumatic valve 57 and automatically opens the 23rd pneumatic valve 51 and the 25th pneumatic valve 53. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the second intermediate filter 54. When the backwashing process lasts for a preset 3 minutes, the backwashing mode of the second intermediate filter 54 ends, and it automatically closes the 23rd and 25th pneumatic valves 51 and automatically opens the 26th pneumatic valve 57, returning to normal operation. When the pressure difference between the 15th pressure gauge 61 and the 17th pressure gauge 72 reaches a preset value of 0.1 MPa, or when the continuous filtration time of the third intermediate filter 60 reaches a preset limit of 8 hours, the third intermediate filter 60 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the 29th pneumatic valve 63 and automatically opens the 27th pneumatic valve 58 and the 30th pneumatic valve 64. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the third intermediate filter 60. When the backwashing process lasts for a preset 3 minutes, the backwashing mode of the third filter 60 ends, automatically closing the 27th pneumatic valve 58 and the 30th pneumatic valve 64, and automatically opening the 29th pneumatic valve 63, returning to normal operation. When the pressure difference between the 16th pressure gauge 68 and the 17th pressure gauge 72 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the fourth filter 67 reaches the preset limit of 8 hours, the fourth filter 67 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the 33rd pneumatic valve 70 and automatically opens the 31st pneumatic valve 65 and the 34th pneumatic valve 71. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the fourth filter 67.When the backwashing process lasts for 3 minutes (preset value), the backwashing mode of the fourth filter 67 ends, and it automatically closes the thirty-first pneumatic valve 65 and the thirty-fourth pneumatic valve 71, and automatically opens the thirty-third pneumatic valve 70, returning to normal operation.

[0040] During operation, when the pressure difference between the eighteenth pressure gauge 76 and the twenty-second pressure gauge 101 of the fine filter module reaches the preset value of 0.1 MPa, or when the continuous filtration time of the first fine filter 73 reaches the preset limit of 8 hours, the first fine filter 73 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the thirty-seventh pneumatic valve 78 and automatically opens the thirty-fifth pneumatic valve 74 and the thirty-eighth pneumatic valve 79. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the first fine filter 73. When the backwashing process lasts for the preset value of 3 minutes, the backwashing mode of the first fine filter 73 ends, and it automatically closes the thirty-fifth pneumatic valve 74 and the thirty-eighth pneumatic valve 79, and automatically opens the thirty-seventh pneumatic valve 78, returning to normal operation. When the pressure difference between the nineteenth pressure gauge 83 and the twenty-second pressure gauge 101 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the second fine filter 82 reaches the preset limit of 8 hours, the second fine filter 82 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the 41st pneumatic valve 85 and automatically opens the 39th and 42nd pneumatic valves 80 and 86. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the second fine filter 82. When the backwashing process lasts for a preset 3 minutes, the backwashing mode of the second fine filter 82 ends, automatically closing the 39th and 42nd pneumatic valves 80 and automatically opening the 41st pneumatic valve 85, returning to normal operation. When the pressure difference between the 20th pressure gauge 90 and the 22nd pressure gauge 101 reaches a preset value of 0.1 MPa, or when the continuous filtration time of the third fine filter 89 reaches a preset limit of 8 hours, the third fine filter 89 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the 45th pneumatic valve 92 and automatically opens the 43rd and 46th pneumatic valves 93. Simultaneously, the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the third fine filter 89. When the backwashing process lasts for a preset 3 minutes, the backwashing mode of the third fine filter 89 ends, automatically closing the forty-third pneumatic valve 87 and the forty-sixth pneumatic valve 93, and automatically opening the forty-fifth pneumatic valve 92, returning to normal operation. When the pressure difference between the twenty-first pressure gauge 97 and the twenty-second pressure gauge 101 reaches the preset value of 0.1 MPa, or when the continuous filtration time of the fourth fine filter 96 reaches the preset limit of 8 hours, the fourth fine filter 96 automatically enters the high-pressure air-water backwashing mode. At this time, the system automatically closes the forty-ninth pneumatic valve 99, automatically opens the forty-seventh pneumatic valve 94 and the fiftieth pneumatic valve 100, and simultaneously the air compressor 137 operates, charging the air tank 136 to perform high-pressure air-water backwashing on the fourth fine filter 96.When the backwashing process lasts for 3 minutes, the backwashing mode of the fourth fine filter 96 ends, and it automatically closes the forty-seventh pneumatic valve 94 and the fiftieth pneumatic valve 100, and automatically opens the forty-ninth pneumatic valve 99, returning to normal operation.

[0041] During operation, if the system pressure decreases due to factors such as reduced local hot water volume, filter backwashing, or automatic system depressurization, and the pressure values ​​of any two of the twenty-second pressure gauges 101, 103, and 104 drop below the set lower limit of the normal pressure range (0.10 MPa), the system will prioritize reducing the frequency of the variable frequency booster pumps based on the booster pump frequency increase / decrease interval, causing the multiple booster pumps already started to operate at low frequency and maintaining the system pressure within the normal pressure range. If the frequency of the multiple variable frequency booster pumps already started has dropped to the set minimum operating frequency of 28 Hz, and the pressure values ​​of any two of the twenty-second pressure gauges 101, 103, and 104 are still below the set lower limit of the normal pressure range (0.10 MPa), the system will execute a pump reduction procedure, prioritizing the shutdown of the last started variable frequency booster pump. After pump reduction, the remaining variable frequency booster pumps will automatically adjust their frequencies according to the aforementioned frequency increase / decrease procedure to maintain the system pressure within the normal pressure range. When the local hot water supply continues to decrease or the well pump stops operating, the system pressure continues to drop. The remaining variable frequency booster pumps will automatically reduce their frequency to the minimum operating frequency according to the aforementioned frequency increase / decrease procedure. If the pressure values ​​of any two of the twenty-second pressure gauges 101, 103, and 104 are still below the lower limit of the set normal pressure range (0.10 MPa), the system will intelligently judge and execute pump reduction-frequency adjustment-pump reduction operations according to the aforementioned procedure until the last variable frequency booster pump is reduced. At this time, the pump will not immediately stop operating at the minimum operating frequency, but will maintain low-frequency operation to protect system safety. The last booster pump will only stop when the pressure values ​​of any two of the twenty-second pressure gauges 101, 103, and 104 are lower than the set pump stop pressure value of 0.03 MPa.

[0042] If, during system operation, the variable frequency booster pump fails to start automatically as instructed, or the inlet pressure of any filter in the coarse / medium / fine filtration module exceeds the set maximum system pressure, it indicates that the reinjection system is blocked and requires emergency pressure relief. At this time, bypass valve 1 and the first check valve 141 automatically open to begin draining and depressurizing. Simultaneously, the emergency alarm system is triggered, sending an alarm signal to inspection personnel for timely repairs, improving emergency response capabilities and maximizing system safety.

Claims

1. An automated control process for an unattended geothermal heating tailwater reinjection system, characterized in that, Includes reinjection wells, multi-stage filtration modules, pressurization modules, and power distribution control modules; Multiple reinjection wells were installed according to the site conditions. Each reinjection well works independently and the geothermal tailwater is reinjected into the ground through the reinjection well. The geothermal tailwater is filtered through a multi-stage filtration module. After being pressurized by a pressurization module, the tailwater is reinjected into the ground through reinjection wells. Each reinjection well is equipped with an independent pressurization pump. Automatic backwashing operation of multi-stage filtration modules: The multi-stage filtration module includes a coarse filtration module, a medium filtration module, and a fine filtration module connected in sequence. Multiple sets of coarse filtration modules are connected in parallel, and each coarse filtration module is equipped with a backwashing structure. The backwashing function is automatically activated based on the pressure difference value or the running time of the coarse filtration module. When one coarse filtration module is backwashed, the other coarse filtration modules continue to operate normally. Multiple sets of medium filtration modules and fine filtration modules are also connected in parallel, and they are also equipped with backwashing structures. The backwashing function is automatically activated based on the pressure difference value or the running time of the filtration modules, so that the multi-stage filtration module is automatically cleaned to meet the requirements of long-term stable filtration. Automatic start-up and frequency adjustment of the pressurization module: The pressurization module includes pressurization pumps and inlet and outlet water pipes. Each pressurization pump is connected in parallel to the main inlet water pipe, which is equipped with a pressure sensor. Each pressurization pump outlet is connected to its corresponding reinjection well via a sealed pipe, and each pressurization pump outlet is equipped with a linked pneumatic valve. Independent pressure sensors and flow meters are installed on the connecting pipes. Parameters include: pump start-up pressure limit, pump stop-down pressure value, normal pressure range, pump start-up sequence, number of pumps started, initial pump start-up frequency, maximum operating frequency of the pressurization pump, minimum operating frequency of the pressurization pump, start-stop interval time of the pressurization pump, and frequency increase / decrease interval time of the pressurization pump. As the geothermal tailwater volume continuously increases, the system pressure rises to... When the pump start-up pressure condition is met, the first booster pump starts. After starting, if the system geothermal tailwater pressure continues to increase and exceeds the upper limit of the normal pressure range, the frequency of the first booster pump is increased first. When the system pressure drops to the normal pressure range, the pump maintains the same frequency. If the system geothermal tailwater pressure is still greater than the upper limit of the normal pressure range after increasing the frequency to the maximum frequency, the second booster pump is automatically started, and so on, increasing the frequency first and then increasing the number of pumps. If the system heating tailwater pressure decreases, the frequency is reduced first. If the pressure still decreases after reducing to the lowest frequency, the pump is stopped, and so on. When increasing the number of pumps, they are started in the set start-up sequence. When stopping the pumps, they are stopped in reverse order of the start-up sequence, with the last pump started stopping first and the first pump started stopping last. The power distribution control module includes a main power distribution cabinet, a booster pump frequency converter cabinet, a main control cabinet, an air compressor, and an air storage tank. The main control cabinet is used to control the automatic backwashing operation of the multi-stage filtration module, the automatic start-up and frequency adjustment of the booster module, and the on / off control of all pneumatic valves.

2. The automatic control process for an unattended geothermal heating tailwater reinjection system according to claim 1, characterized in that, The inlet / outlet and backwash outlet of the coarse filtration module are equipped with pneumatic control valves. Each coarse filtration module inlet is equipped with an inlet pressure sensor, and the main outlet pipe of the coarse filtration module is equipped with an outlet pressure sensor. Each sensor and control valve is connected to the CPU of the coarse filtration module via a 485 signal control line, and the CPU is then connected to the main control cabinet via a dedicated line. The intermediate filtration module and the fine filtration module are equipped with pneumatic control valves, inlet water pressure sensors, and outlet water pressure sensors with the same functions, as well as a CPU dedicated to the intermediate filtration module and a CPU dedicated to the fine filtration module. They are then connected to the main control cabinet via dedicated lines. The backwashing function of the multi-stage filtration module is activated when the pressure difference monitored by the pressure sensor at the inlet / outlet is triggered by a threshold; or a threshold is set for the continuous filtration time of the multi-stage filtration module, and the backwashing function is activated when the pressure difference is not reached but the filtration time reaches the threshold. The backwashing function is automatically activated by judging the dual conditions.

3. The automatic control process for an unattended geothermal heating tailwater reinjection system according to claim 2, characterized in that, The backwashing structure of the intermediate filter module and the fine filter module is also equipped with a high-pressure air inlet. When the backwashing function is turned on, high-pressure water and high-pressure air are introduced at the same time, and backwashing is carried out by mixing high-pressure air and water.

4. The automatic control process for an unattended geothermal heating tailwater reinjection system according to claim 1, characterized in that, At least two pressure sensors are installed on the main inlet pipe of the pressurization module. When the pressure values ​​of any two of the two pressure sensors on the main inlet pipe of the pressurization module and the main outlet pressure sensor of the fine filtration module reach the set pump start pressure limit, the pressurization pump will start automatically. By judging the combined values ​​of multiple pressure sensors, the safety and accuracy of the automatic start and frequency regulation operation of the pressurization module can be improved.

5. The automatic control process for an unattended geothermal heating tailwater reinjection system according to claim 1, characterized in that, A pneumatic valve is installed between the booster pump and the reinjection well. When the booster pump needs to be started, the corresponding pneumatic valve opens automatically first, and the booster pump starts after the valve opens. When the booster pump needs to be stopped, the pump stops first, and the pneumatic valve closes automatically after the booster pump stops completely. This prevents the high-pressure water in the reinjection well from flowing back and causing erosion to the booster pump, multi-stage filtration module equipment, and other equipment after the booster pump stops.

6. The automatic control process for an unattended geothermal heating tailwater reinjection system according to claim 1, characterized in that, The main inlet of the reinjection system is equipped with a bypass valve and a bypass pipe. If the pressure value monitored by 30-50% of the inlet pressure sensors of the coarse filter module exceeds the safety threshold, the bypass valve and bypass pipe will be activated for emergency pressure relief, and an alarm will be issued at the same time.

7. The automatic control process for an unattended geothermal heating tailwater reinjection system according to claim 1, characterized in that, The ratio of the number of coarse filtration modules, medium filtration modules and fine filtration modules is 3:(1.5-2):(1.5-2), wherein the number of medium filtration modules is not less than the number of fine filtration modules.

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