A smart variable flow positive pressure compensation control system and compensation method

Abstract

The application discloses an intelligent variable-flow positive pressure backfill control system and a backfill method. The backfill control system is arranged with a plurality of backfill branch pipelines in the space of the water-stopping clay ball above the external filter layer of the backfill well. One end of each backfill branch pipeline is in communication with the backfill well pipe, and the other end is in communication with the external backfill main pipeline, thereby forming independent positive backfill channels. The positive backfill channels at least contain a water supply power device. Meanwhile, combined with elements such as a fluid controller, a flow detector, a pressure sensor, a liquid level detector, a water supply power device and a smart control center, intelligent positive pressure backfill under the condition of variable flow is realized, and gas blockage and chemical and biological blockage caused by the gas blockage are effectively prevented and controlled.

Description

Technical Field

[0001] This invention belongs to the technical field of underground / underwater structures, and particularly relates to an intelligent variable flow positive pressure replenishment control system and replenishment method. Background Technology

[0002] Artificial recharge of deep groundwater using well irrigation is one of the important and effective methods for preventing land subsidence and seawater intrusion in key areas.

[0003] There are generally two ways to replenish water into an aquifer: one is to introduce water into the wellhead via pipeline and then directly into the well; the other is to introduce water into the well through pipeline until it is below the groundwater level. In both methods, especially when the flow rate changes, the water often enters the well in a waterfall-like flow, which easily carries a large amount of gas. This not only causes gas blockage but also easily induces related chemical and biological blockages, reducing replenishment efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent variable flow positive pressure compensation control system and compensation method, which realizes intelligent positive pressure compensation under variable flow conditions and effectively prevents gas blockage and the chemical and biological blockages it causes.

[0005] To solve the above problems, the technical solution of the present invention is as follows:

[0006] An intelligent variable flow positive pressure compensation control system includes:

[0007] Multiple recharge branch pipes are laid in the space of the water-stopping clay ball above the filter material layer outside the recharge well. One end of each recharge branch pipe is connected to the recharge well pipe, and the other end is connected to the external recharge main pipe, forming an independent forward recharge channel. These forward recharge channels include at least one water supply power device.

[0008] The flow control device includes an intelligent control center, at least one pressure sensor, at least one flow detector, and at least one fluid controller installed on each positive return channel, wherein...

[0009] The intelligent control center is further configured to: control the corresponding number of positive replenishment channels according to the preset replenishment flow stage, adapt to the opening of each fluid controller and / or the power energy of the water supply power unit, and realize positive pressure variable flow replenishment.

[0010] According to one embodiment of the present invention, an automatic venting triggering device is provided on the forward replenishment channel. The automatic venting triggering device further includes an automatic ventilator installed at the highest point of the pipe protrusion in the forward replenishment channel. The automatic ventilator realizes the switching between a venting state and a venting-off state, wherein:

[0011] At the beginning of the replenishment process, there is no water in the automatic exhaust valve, and it is in a venting state.

[0012] As water flows into the pipeline of the positive return channel, the gas in the pipeline is gradually discharged from the automatic air vent. At the same time, the water in the pipeline gradually rises. When it rises into the automatic air vent, the float in the automatic air vent blocks the air outlet of the automatic air vent under the action of buoyancy and water pressure, and enters the air-closed state to achieve positive pressure return.

[0013] According to one embodiment of the present invention, the diameter and number of the replenishment branch pipelines are determined based on the maximum replenishment capacity of the replenishment well and the pipeline flow calculation model, wherein the pipeline flow calculation model is further configured to use the Darcy-Weisbach formula for calculation:

[0014] ΔP = f * (L / D) * (ρ * v 2 / 2) + K * (ρ * v 2 / 2)

[0015] Where ΔP is the required driving pressure difference between the inlet and outlet of the replenishment sub-pipeline, f is the friction coefficient, L is the length of the replenishment sub-pipeline, D is the diameter of the replenishment sub-pipeline, ρ is the fluid density, v is the flow velocity, and K is the local loss coefficient.

[0016] The replenishment capacity of the well when the water level in the replenishment well is stable near the wellhead is taken as the maximum replenishment capacity Qmax. The number of replenishment branches is obtained based on the maximum replenishment capacity Qmax and the flow rate of a single replenishment branch.

[0017] According to one embodiment of the present invention, the intelligent control center is further configured as follows:

[0018] Based on the capacity of the replenishment well, set multi-stage replenishment flow thresholds, open different numbers of replenishment sub-pipelines in the positive replenishment channels in stages, and control the speed of the water supply power unit to maintain the target flow rate.

[0019] Furthermore, it monitors current data including flow rate, pressure, and water level in real time. During any stage of operation, if the real-time flow rate is higher than the target flow rate, the speed of the water supply power unit is reduced; if the real-time flow rate is lower than the target flow rate, the speed of the water supply power unit is increased; if the real-time pressure is greater than the preset pressure limit or the water level in the well is less than the preset threshold, all fluid controllers are immediately cut off and the water supply power unit is shut down to achieve safety interlocking. The water level data is collected from the liquid level detector in the replenishment well.

[0020] According to one embodiment of the present invention, the intelligent control center pre-stores at least three stages of variable flow positive pressure replenishment strategy, and sequentially forms the first stage of single-pipe operation, the second stage of dual-pipe parallel operation, and the third stage of multi-pipe operation along the direction of increasing flow; when the actual flow rate Q exceeds the replenishment flow rate threshold of the corresponding stage, it automatically enters the next stage to maintain the water level in the well and full positive pressure flow throughout the process.

[0021] According to an embodiment of the present invention, in the single-pipe operation of the first stage, only the fluid controller on the first positive backfill channel is opened, with the first target flow rate q1 as the set value. The actual flow rate Q in this positive backfill channel is collected in real time, Q is compared with the first target flow rate q1, and the rotational speed of the water supply power device is adjusted according to the comparison result to make Q = q1 and maintain the positive pressure in the pipeline, realizing precise backfill with low flow rate.

[0022] According to an embodiment of the present invention, when Q ≥ Q1, it enters the second stage of dual-pipe parallel operation. The fluid controller on the second positive backfill channel is opened, with the second target flow rate q2 as the set value. The actual total flow rate in the two positive backfill channels is collected in real time, and this actual total flow rate is compared with the second target flow rate q2. The rotational speed of the water supply power device is adjusted according to the comparison result to make the actual total flow rate = q2 and maintain the positive pressure in the pipeline; where q2 > q1, and Q1 is the backfill flow rate threshold for the first stage set according to the capacity of the backfill well.

[0023] According to an embodiment of the present invention, when Q ≥ Q2, it enters the third stage of multi-pipe operation. The fluid controller on the third positive backfill channel is opened, with the third target flow rate q3 as the set value. The actual total flow rate in the positive backfill channels participating in the backfill is collected in real time, and this actual total flow rate is compared with the third target flow rate q3. The rotational speed of the water supply power device is adjusted according to the comparison result to make the actual total flow rate = q3 and maintain the positive pressure in the pipeline; where q2 < q3 ≤ Qmax, Qmax is the maximum backfill capacity of the well corresponding to the limit water level near the wellhead; Q2 is the backfill flow rate threshold for the second stage set according to the capacity of the backfill well, and Q2 > Q1.

[0024] An intelligent variable-flow positive-pressure backfill control system includes:

[0025] A backfill well, in which the space above the filter material layer on the periphery of the well pipe is filled with water-stop clay balls;

[0026] Multiple backfill branch pipelines are buried in the water-stop clay balls. One end of each backfill branch pipeline is connected to the backfill well pipe, and the other end is connected to the external backfill main pipeline, forming independent positive backfill channels. These positive backfill channels at least include a water supply power device;

[0027] A flow rate regulation device includes an intelligent control center, at least one pressure sensor, at least one flow rate detector, and at least one fluid controller provided on each positive backfill channel. Among them,

[0028] The intelligent control center is further configured to: control the corresponding number of positive backfill channels according to the preset backfill flow rate stage, adapt the opening of each fluid controller and / or the power energy of the water supply power device, and realize positive-pressure variable-flow backfill.

[0029] A compensation method for a smart variable flow positive pressure compensation control system includes the following steps:

[0030] S1: Based on the maximum replenishment capacity Qmax of the replenishment well, the stable water level in the well, and the parameters of the replenishment sub-pipeline, the Darcy-Weisbach formula considering friction loss and local head loss is adopted to pre-calculate and set the replenishment flow thresholds Q1, Q2, ..., Qn-1 for each stage, as well as the target flow rates q1, q2, ... qn for each stage;

[0031] S2: Write the replenishment flow threshold and target flow into the intelligent control center, start the water supply power unit, and perform multi-stage replenishment according to the following sub-steps:

[0032] S2-1: First stage: Only open the fluid controller in the first positive return channel, and adjust the speed of the water supply power unit to stabilize the flow detector reading at q1;

[0033] S2-2: Second stage: When the flow rate rises to Q1, open the fluid controller in the second positive return channel and continue to adjust the water supply power device to stabilize the flow rate at q2;

[0034] S2-3: And so on, until the fluid controller in the nth positive return channel is opened in the nth stage to stabilize the flow rate at qn;

[0035] S3: During operation at each stage, if the real-time flow rate is higher than the target flow rate, the intelligent control center will reduce the speed of the water supply power unit; if the real-time flow rate is lower than the target flow rate, the speed of the water supply power unit will be increased.

[0036] S4: After completing the nth stage of replenishment, the intelligent control center shuts down the water supply power unit and all fluid controllers;

[0037] S5: During operation, if the pressure sensor detects that the pressure in the main replenishment pipeline exceeds the upper pressure limit or the level detector detects that the water level in the well is less than the preset threshold, the intelligent control center will immediately execute the water outage protection and issue an alarm.

[0038] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art:

[0039] The intelligent variable flow positive pressure replenishment control system in one embodiment of the present invention utilizes the space above the filter layer outside the replenishment well pipe to lay multiple replenishment branch pipelines from the wellhead to the inside of the well. At the same time, it combines components such as fluid controller, flow detector, pressure sensor, liquid level detector, water supply power device and intelligent control center to realize intelligent positive pressure replenishment under variable flow conditions, effectively preventing gas blockage and the chemical and biological blockages it causes. Attached Figure Description

[0040] Figure 1This is a schematic diagram of the intelligent variable flow positive pressure compensation control system in one embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of an automatic exhaust device according to an embodiment of the present invention;

[0042] Figure 3 This is a flowchart of an intelligent variable flow positive pressure compensation method according to an embodiment of the present invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1: Replenishment well; 2: Replenishment branch pipeline; 3: Replenishment main pipeline; 4: Water supply power unit; 5: Pressure sensor; 6: Flow detector; 7: Automatic vent; 8: Fluid controller; 9: Liquid level detector; 10: Intelligent control center; 11: Water storage tank; 12: Filter media layer; 13: Water-stopping clay ball; 14: Hump; 15: Float; 16: Vent. Detailed Implementation

[0045] The present invention provides a more detailed description of an intelligent variable flow positive pressure compensation control system and compensation method, in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims.

[0046] The filter pipes of deep groundwater recharge wells are often located at depths below 170m. In addition to filling the upper part of the filter pipe with 10-20m of filter material, the upper part of the filter pipe is basically filled with water-stopping clay balls near the wellhead.

[0047] To effectively prevent the formation of waterfall flow, this embodiment utilizes the space above the filter layer outside the well casing of the replenishment well to lay multiple replenishment branch pipelines from the wellhead to the inside of the well. At the same time, combined with components such as fluid controllers, flow detectors, pressure sensors, liquid level detectors, water supply power devices, and intelligent control centers, intelligent positive pressure replenishment under variable flow conditions is realized, effectively preventing gas blockage and the chemical and biological blockages it causes.

[0048] Example 1

[0049] Please refer to Figure 1 This embodiment provides an intelligent variable flow positive pressure compensation control system, including:

[0050] Multiple recharge branch pipes 2 are laid in the space of the water-stopping clay ball 13 above the external filter layer 12 of the recharge well 1. One end of each recharge branch pipe 2 is connected to the recharge well pipe, and the other end is connected to the external recharge main pipe 3, forming an independent positive recharge channel. These positive recharge channels include at least one water supply power device 4.

[0051] The flow control device includes an intelligent control center 10, at least one pressure sensor 5, at least one flow detector 6, and at least one fluid controller 8 installed on each positive return channel. The intelligent control center 10 is further configured to control the corresponding number of positive return channels according to the preset return flow stage, adapt to the opening of each fluid controller and / or the power energy of the water supply power device, and realize positive pressure variable flow return.

[0052] The aforementioned water supply power unit 4 can be a submersible pump, a variable frequency constant pressure water supply power unit, a negative pressure-free water supply power unit, a high-efficiency permanent magnet intelligent water supply power unit, etc.; the fluid controller 8 can be a solenoid valve, an electric valve, a ball valve, etc.; the flow detector 6 can be a vortex flow meter, an electromagnetic flow meter, etc.; the pressure sensor 5 can be a pressure transmitter, a differential pressure sensor, etc.; each component can be selected according to the actual situation.

[0053] This implementation utilizes a collaborative design of "external pipe installation + positive pressure full flow + intelligent control of staged variable flow" to ensure that, in deep groundwater artificial recharge scenarios, the outlet remains below the static water level, and multiple recharge branch pipes form a "multi-point, low-position, positive pressure" inflow within the water-stopping clay ball. Compared to conventional wellhead drop-type water recharge, this reduces the amount of air carried by the inflow by more than 90% (40 m). 3 Comparative experiment of DO under / h conditions: DO1 < 2 mg / L, DO2 > 8 mg / L), thereby completely inhibiting gas lock and the chemical-biological blockage it induces.

[0054] Specifically, multiple replenishment branch pipes 2 are laid inside the water-stopping clay ball 13 on the upper part of the filter material layer outside the replenishment well. The connection point between them and the replenishment well is below the static water level inside the well. The replenishment branch pipes 2 are made of steel pipes, stainless steel pipes or PPR pipes with a certain pressure resistance. The number and diameter of the branch pipes are determined according to the maximum replenishment capacity of the replenishment well and the replenishment plan. The diameter of the replenishment branch pipes must be designed to meet the requirement of full-flow positive pressure replenishment of a single replenishment branch pipe under the minimum replenishment flow scheme.

[0055] The number of replenishment branch lines needs to be determined based on the well's replenishment capacity and replenishment plan (i.e., flow rate, constant flow rate or variable flow rate). The well's replenishment capacity is related to its diameter, filter pipe length, and the lithology, thickness, and permeability of the formation corresponding to the filter pipe. Therefore, determining the number of replenishment branch lines requires conducting replenishment tests using similar wells in the area before well construction to determine the well's replenishment capacity, and then using pipe flow calculation formulas to determine the number and diameter of the replenishment branch lines. The replenishment branch lines are connected to the well casing at intervals using welding or bolts to prevent settlement. The replenishment branch lines use steel pipes, stainless steel pipes, or PPR pipes with high compressive strength to effectively control deformation.

[0056] The ability of water in a replenishment well to diffuse to the surrounding area (replenishment capacity) is directly related to the water level in the well. Before constructing a replenishment well in each region, replenishment tests of similar wells should be conducted to determine the replenishment capacity of the well at different water levels. When the flow rate in the replenishment pipeline is the same as the well's diffusion capacity, the water level in the well remains stable. When the flow rate in the replenishment pipeline is greater than the well's diffusion capacity, the water level in the well rises, and the well's replenishment capacity is enhanced. When the pipeline flow rate is the same as the replenishment capacity, the water level in the well remains unchanged. Therefore, the stable water level in the well under the designed replenishment flow rate can be calculated based on the relationship between the well's replenishment capacity and the well's water level. In pipe flow, based on Bernoulli's equation in fluid mechanics, and taking into full account the head loss caused by pipe friction and bends, a pipe flow calculation model is adopted, such as the Darcy-Weisbach empirical formula. This model can establish the relationship between the diameter, length, material, and bends of the replenishment sub-pipe, the head difference between the two ends of the replenishment pipe (i.e., the difference between the sum of the pressure and position head at the wellhead and the water level in the well at the design flow rate), and the outlet flow rate of the replenishment pipe (i.e., the minimum designed replenishment flow rate). The condition for achieving positive pressure replenishment is the pipe diameter when the pressure at the wellhead is positive, that is, when the pipe pressure at the wellhead is zero, the calculated pipe diameter is the maximum diameter that meets the requirements.

[0057] The diameter of the backfill branch pipe can be determined using the following formula:

[0058] D = f (Qmin,△H,L,λ,ΣK)

[0059] Where Qmin is the minimum design recharge flow rate, ΔH is the difference between the inlet pressure head and the stable water level in the well, L is the pipe length, λ is the friction coefficient, and ΣK is the sum of local resistance coefficients; when the gauge pressure at the wellhead is zero, the obtained D is the maximum inner diameter that satisfies the positive pressure full flow.

[0060] Alternatively, the Darcy-Weisbach formula can be used for calculation:

[0061] ΔP = f * (L / D) * (ρ * v 2 / 2) + K * (ρ * v 2 / 2)

[0062] Where ΔP is the required driving pressure difference between the inlet and outlet of the replenishment sub-pipe, f is the friction coefficient, L is the length of the replenishment sub-pipe, D is the diameter of the replenishment sub-pipe, ρ is the fluid density, v is the flow velocity, and K is the local loss coefficient; with ΔP fixed, the diameter D can be calculated by knowing f, L, ρ, v and K.

[0063] The replenishment capacity of the well when the water level in the replenishment well is stable near the wellhead is taken as the maximum replenishment capacity Qmax. The number of replenishment branches is obtained based on the maximum replenishment capacity Qmax and the flow rate of a single replenishment branch.

[0064] In one embodiment, the upstream end of the main replenishment pipeline 3 is connected to the water supply power unit 4, and its downstream end is independently connected to the upstream end of each replenishment branch pipeline 2. The diameter of any replenishment branch pipeline 2 is smaller than the diameter of the main replenishment pipeline 3. One end of each replenishment branch pipeline 2 is connected to the replenishment well pipe, and the other end is connected to the external replenishment main pipeline 3, forming an independent forward replenishment channel. The water supply power unit 4 is located in the water storage tank 11, and the fluid controller 8 is installed on each replenishment branch pipeline 2. The flow detector 6 and the pressure sensor 5 can be installed on the main replenishment pipeline 3.

[0065] Furthermore, each return branch pipe 2 and the return main pipe 3 form an upwardly protruding hump 14 at the connection point. An automatic air vent 7 is installed on the top of the hump 14. The automatic air vent 7 opens to vent when the pipe is not full of water and automatically closes when the pipe is full of water to maintain positive pressure.

[0066] The connection between the replenishment branch pipeline and the external replenishment main pipeline is protruding to ensure that the flow detector on the main replenishment pipeline is always in a full-flow state, thereby ensuring the monitoring accuracy of the flow detector.

[0067] Please refer to Figure 2 The automatic exhaust device 7 can be a float-type structure, with its lower opening directly and sealed to the highest point of the return branch pipe 2, forming the apex of the return branch pipe. The automatic exhaust device 7 includes an axial exhaust channel and a float 15 that floats up and down within the channel. The density of the float 15 is less than 0.5 g / cm³. 3 Furthermore, the sealing pressure between its upper sealing surface and the lower port of the channel is ≥0.02 MPa. The opening and closing triggering mechanism of this automatic exhaust valve is determined solely by whether the valve body is filled with water, specifically:

[0068] Before the replenishment begins, the valve body is empty and the pipe is in an empty state. The float falls, the exhaust channel is fully open, and the gas in the pipe is freely discharged.

[0069] As the replenishment water enters, the water level rises to the top of the hump and instantly submerges the buoy. Under the combined action of buoyancy and water pressure of ≥0.01 MPa, the buoy quickly rises and completely blocks the exhaust port 16 of the exhaust channel, causing the replenishment branch pipeline to immediately switch to a closed full-flow state, forming a continuous positive pressure of ≥0.02 MPa at the outlet of the replenishment branch pipeline, thus achieving positive pressure replenishment.

[0070] When gas reappears in the replenishment pipeline, causing the water level to drop, the float will automatically fall and reopen the venting valve until the valve is full of water again, always maintaining a full-pipe positive pressure condition.

[0071] Therefore, the trigger mechanism for the automatic exhaust valve to open and close is whether there is water inside the exhaust valve body. Since it is located at the highest point of the pipeline, when the automatic exhaust valve is full of water, the entire pipeline is also full of water. In other words, whether the pipeline is full of water is its trigger mechanism.

[0072] The diameter of the main replenishment pipeline 3 is larger than the diameter of the peripheral replenishment branch pipeline 2 of the replenishment well. A fluid controller 8 is installed on each of the branch pipelines at the connection point. A pressure sensor 5 and a flow detector 6 are installed on the main replenishment pipeline 3, and the other end is connected to the water supply power unit 4 in the water storage tank 11.

[0073] The pressure sensor should be determined based on the pressure required to maintain a certain recharge flow rate. Generally, the pipeline pressure and recharge flow rate should be determined within a limited range based on the well's recharge capacity. This range can ensure the monitoring accuracy of the pressure sensor and flow detector.

[0074] However, if the flow rate and pressure vary greatly during the replenishment process, the range of the pressure and flow detectors on the main replenishment pipeline should be designed to meet the monitoring accuracy requirements under high pressure and high flow. To meet the monitoring accuracy requirements of flow and pressure under low flow replenishment, at least one pressure and flow detector with a small range can be installed on the replenishment branch pipeline under low flow replenishment conditions to ensure the monitoring accuracy under low flow conditions.

[0075] For example, if a "large range" pressure sensor with a range of 0–1.6 MPa is selected on the main return pipeline, then a "small range" pressure transmitter with a range of 0–0.1 MPa (≈ 0–10 mH2O) can be connected to one of the return branch pipelines. The model is HY-MP-0.1B (4–20 mA output, accuracy ±0.25 %FS).

[0076] When the system is at 5–15 m 3 During the low flow replenishment phase at / h, the intelligent control center automatically switches to read the signal from the small-range sensor, which can obtain a small differential pressure resolution of 0.3–3 kPa, thereby ensuring that the pressure monitoring accuracy under low flow is still within ±0.25%.

[0077] The intelligent control center 10 is mainly composed of electronic components such as switching power supply, PLC-CPU module, communication module, frequency converter, relay, and I / O module. It can receive monitoring data and send instructions to power and control equipment. It is connected to pressure sensor, liquid level detector, flow detector, water supply power unit and fluid controller.

[0078] The control logic of the intelligent control center is to adjust the required number of replenishment branch pipes (i.e., by controlling the fluid controllers on each replenishment branch pipe) and the water supply flow (i.e., by adjusting the speed of the water supply power unit) in a timely manner according to the required replenishment flow at different stages of the design. The number of replenishment branch pipes required under different replenishment flow rates needs to be determined according to the Bernoulli equation that takes into account the head loss along the way, i.e., the empirical formula for pipe flow.

[0079] Its operating principle is as follows: various control devices (fluid controllers, water supply power units), monitoring devices (flow detectors, pressure sensors) and other electronic components judge and execute commands through current signals. The flow and pressure monitoring values ​​are transmitted to the PLC-CPU module as current signals. The module generates different current signal commands based on the flow and pressure parameter thresholds set internally and transmits them to the control devices. The control devices such as fluid controllers and water supply power units execute commands to open or close or increase or decrease the speed according to the current signals.

[0080] In this embodiment, the intelligent control center 10 is configured to: set multi-stage replenishment flow thresholds according to the replenishment well capacity, open different numbers of replenishment sub-pipes in the forward replenishment channels in stages, and control the rotation speed of the water supply power unit to maintain the target flow rate.

[0081] Furthermore, the system monitors current data, including flow rate, pressure, and water level, in real time. During any stage of operation, if the real-time flow rate is higher than the target flow rate, the speed of the water supply power unit is reduced; if the real-time flow rate is lower than the target flow rate, the speed of the water supply power unit is increased; if the real-time pressure is greater than the preset pressure limit or the water level in the well is less than the preset threshold from the wellhead, all fluid controllers are immediately cut off and the water supply power unit is shut down to achieve safety interlocking. The water level data is collected from the liquid level detector 9 in the replenishment well. The liquid level detector 9 can be a pressure liquid level gauge, radar liquid level gauge, magnetic float liquid level gauge, etc.

[0082] The intelligent control center pre-stores at least three stages of variable flow rate positive pressure replenishment strategy, which sequentially forms the first stage of single-pipe operation (hereinafter referred to as the first stage), the second stage of dual-pipe parallel operation (hereinafter referred to as the second stage), and the third stage of multi-pipe operation (hereinafter referred to as the third stage) along the direction of increasing flow rate. When the actual flow rate Q exceeds the replenishment flow rate threshold of the corresponding stage, it automatically enters the next stage to maintain the water level in the well and full positive pressure flow throughout. The following uses the three-stage variable flow rate positive pressure replenishment strategy as an example to illustrate:

[0083] Phase 1: Only activate the fluid controller on the first positive return channel, and adjust the speed of the water supply power unit to stabilize the flow rate of the return main pipeline at q1;

[0084] Second stage: When the flow rate rises to Q1, the fluid controller on the second positive replenishment channel is activated, and the water supply power device is adjusted to stabilize the flow rate at q2.

[0085] Third stage: When the flow rate rises to Q2, the fluid controller on the third positive replenishment channel is activated, and the water supply power device is adjusted to stabilize the flow rate at q3.

[0086] Where Q1 and Q2 are the set replenishment traffic thresholds for each stage, with Q2 > Q1; q1, q2, and q3 are the target traffic for each stage, with q1 > Q2 > Q1. <q2<q3≤Qmax。

[0087] Specifically, in the first stage of positive pressure replenishment, the intelligent control center only outputs an open signal to the fluid controller of the first positive replenishment channel (or the first replenishment branch pipeline), enabling the first positive replenishment channel to conduct. The flow detector collects the actual flow rate Q of the main replenishment pipeline in real time and feeds it back to the intelligent control center. The built-in comparator of the intelligent control center compares Q with the preset first target flow rate q1, outputs a deviation signal to drive the frequency converter to adjust the speed of the water supply power unit, so that Q = q1 and maintains the pressure of the main replenishment pipeline ≥ 0.02 MPa, forming the first stage of full-flow positive pressure replenishment;

[0088] When an external command or built-in timing requirement increases to the second stage flow rate, the intelligent control center compares the actual flow rate Q with the preset opening threshold Q1. If Q ≥ Q1, an opening signal is output to the fluid controller of the second positive return channel to enable the second positive return channel to be integrated. The flow detector continues to collect the actual flow rate and provide feedback. The comparator uses the second target flow rate q2 as the set value and adjusts the speed of the water supply power unit to make Q = q2 and the pressure still ≥ 0.02 MPa, thus forming the second stage full-flow positive pressure return.

[0089] When the third stage of flow is required, the intelligent control center compares the actual flow rate Q with the preset opening threshold Q2. If Q≥Q2, it outputs an opening signal to the fluid controller of the third positive return channel so that the third positive return channel is incorporated. The flow detector acts as a feedback element again, and the comparator uses the third target flow rate q3 as the set value to adjust the speed of the water supply power unit so that Q=q3 and maintains full flow positive pressure in the entire pipeline, thus completing the third stage of positive pressure return.

[0090] Furthermore, the intelligent control center is equipped with a safety protection module. During any stage of positive pressure replenishment operation, the pressure sensor and the liquid level detector simultaneously input real-time pressure P and well water level H to the intelligent control center. If P > Pmax or H is less than the preset threshold at the wellhead, the intelligent control center immediately cuts off all fluid controllers and shuts down the water supply power unit to achieve safety interlocking.

[0091] The upper pressure limit Pmax is determined according to the following principles:

[0092] Pmax = Ppipe - ρgh

[0093] Where Ppipe is the rated pressure of the ground pipeline and the replenishment branch pipeline, h is the depth of the replenishment branch pipeline outlet from the ground, and ρgh is the hydrostatic pressure at the outlet.

[0094] The aforementioned variable flow positive pressure replenishment is set according to the inflow pattern of the replenishment water source and the needs of the replenishment test plan. Different inflow water volumes correspond to the activation of different numbers of fluid controllers. The purpose is to ensure that positive pressure replenishment can be achieved under different flow rates. The smaller the set replenishment flow rate, the fewer fluid controllers need to be activated, thus ensuring positive pressure replenishment. If too many replenishment branch lines are activated, positive pressure replenishment cannot be achieved. The larger the set replenishment flow rate, the more fluid controllers need to be activated. If there are few replenishment branch lines, the pressure that the pipeline needs to maintain in order to maintain a large flow rate replenishment will be greater, which may exceed the pipeline pressure resistance threshold.

[0095] The first stage only activates the first positive replenishment channel because, based on the target flow rate q1 and relevant parameters of the replenishment well, the flow rate empirical formula is used to calculate that, under the condition of the target flow rate q1, achieving positive pressure replenishment only requires activating the fluid controller of the first replenishment branch pipeline. Activating too many fluid controllers would make it difficult to achieve positive pressure replenishment. Similarly, for the second stage target flow rate q2 and the third stage target flow rate q3, under the condition of achieving positive pressure replenishment and ensuring pipeline pressure safety, the number of replenishment branch pipelines and the number of fluid controllers to be activated can be calculated using the flow empirical formula. These values ​​are then input into the operation indicator threshold setting section of the intelligent control center, thereby achieving automatic activation and operation at different stages. In short, different replenishment flow rates correspond to an appropriate number of replenishment branch pipelines (calculated based on the replenishment well parameters using the flow empirical formula). Activating too few replenishment branch pipelines and fluid controllers will cause excessive pipeline pressure, leading to safety accidents; activating too many replenishment branch pipelines will make it difficult to achieve positive pressure replenishment.

[0096] The intelligent variable flow positive pressure replenishment control system in this embodiment utilizes part of the space above the water-stopping clay ball on the outer filter layer of the deep replenishment well to lay multiple replenishment branch pipelines. While saving space within the replenishment well pipe, it achieves positive pressure replenishment under various replenishment flow rates, effectively preventing the formation of waterfall flow and thus significantly controlling gas blockage and the resulting chemical and biological blockages. Using a water supply power unit, flow detector, pressure sensor, level detector, fluid controller, and intelligent control center, multi-stage variable flow positive pressure intelligent replenishment can be achieved, while ensuring the safety of the pipeline and replenishment well, greatly saving manpower and resources.

[0097] The effectiveness of the clogging test can be verified by comparing the clogging efficiency (the ratio of clogging flow rate to water level rise) between clogging tests under positive pressure and non-positive pressure conditions. (Using a 40m...) 3For example, in a positive pressure replenishment test, based on the empirical formula for pipe flow, it is calculated that two replenishment branch lines can achieve positive pressure replenishment. The two replenishment branch lines are automatically opened according to a pre-set program for continuous constant flow replenishment for three days. The rise in well water level after three days relative to the water level before replenishment (H1) is recorded. Replenishment is then stopped, and the well is pumped for one hour, while the dissolved oxygen content (DO1) of the pumped water is measured. Two days after pumping stops, the well water level returns to its natural level, and a non-positive pressure replenishment test is conducted, i.e., four replenishment branch lines are opened. Under this replenishment condition, each air vent valve remains open throughout the three-day replenishment process, and gas enters the pipeline from the air vent valves and flows into the aquifer with the water flow. The rise in well water level after three days relative to the water level before replenishment (H2) is recorded. The replenishment water supply power device is then shut off, and the well is pumped for one hour, while the dissolved oxygen content (DO2) of the pumped water is measured. By comparing the values ​​of DO1 and DO2, and 40 / H1 and 40 / H2, we can determine the dissolved oxygen content and recharge efficiency of the extracted water under the two conditions, thus verifying the control of gas blockage.

[0098] Example 2

[0099] The difference between this embodiment and Embodiment 1 is that, when well digging is required, the intelligent variable flow positive pressure compensation control system includes:

[0100] For replenishment wells, the space above the filter material layer surrounding the well casing is filled with water-stopping clay balls.

[0101] Multiple replenishment branch pipes are buried in the water-stopping clay ball. One end of each replenishment branch pipe is connected to the replenishment well pipe, and the other end is connected to the external replenishment main pipe, forming an independent forward replenishment channel. These forward replenishment channels include at least one water supply power device.

[0102] The flow control device includes an intelligent control center, at least one pressure sensor, at least one flow detector, and at least one fluid controller installed on each positive return channel, wherein...

[0103] The intelligent control center is further configured to: control the corresponding number of positive replenishment channels according to the preset replenishment flow stage, adapt to the power energy of each fluid controller opening and / or water supply power device, and realize positive pressure variable flow replenishment.

[0104] The implementation method of this device is the same as that of Embodiment 1, except for well digging, and will not be described again here.

[0105] For the compensation method of the intelligent variable flow positive pressure compensation control system in the above embodiments, please refer to [link / reference needed]. Figure 3 This includes the following steps:

[0106] S1: Based on the maximum replenishment capacity Qmax of the replenishment well, the stable water level in the well, and the parameters of the replenishment sub-pipeline, the Darcy-Weisbach formula considering friction loss and local head loss is adopted to pre-calculate and set the replenishment flow thresholds Q1, Q2, ..., Qn-1 for each stage, as well as the target flow rates q1, q2, ... qn for each stage;

[0107] S2: Write the replenishment flow threshold and target flow into the intelligent control center, start the water supply power unit, and perform multi-stage replenishment according to the following sub-steps:

[0108] S2-1: First stage: Only open the fluid controller in the first positive return channel, and adjust the speed of the water supply power unit to stabilize the flow detector reading at q1;

[0109] S2-2: Second stage: When the flow rate rises to Q1, open the fluid controller in the second positive return channel and continue to adjust the water supply power device to stabilize the flow rate at q2;

[0110] S2-3: And so on, until the fluid controller in the nth positive return channel is opened in the nth stage to stabilize the flow rate at qn;

[0111] S3: During operation at each stage, if the real-time flow rate is higher than the target flow rate, the intelligent control center will reduce the speed of the water supply power unit; if the real-time flow rate is lower than the target flow rate, the speed of the water supply power unit will be increased.

[0112] S4: After completing the nth stage of replenishment, the intelligent control center shuts down the water supply power unit and all fluid controllers;

[0113] S5: During operation, if the pressure sensor detects that the pressure in the main replenishment pipeline exceeds the upper pressure limit or the level detector detects that the water level in the well is less than the preset threshold, the intelligent control center will immediately execute the water outage protection and issue an alarm.

[0114] Specifically, before formal replenishment, a constant flow replenishment test can be conducted in similar wells within the same hydrogeological block to determine the actual replenishment capacity at different well water levels. A water level-replenishment capacity relationship curve can then be fitted, and the replenishment flow thresholds Q1, Q2, ..., Qn-1 and target flow rates q1, q2, ... qn can be verified to ensure that the well water level remains within a safe range and maintains a positive pressure full flow state. The replenishment flow threshold can be considered as the activation threshold for the fluid controller in all stages except the first stage.

[0115] Based on the maximum replenishment capacity (Qmax) of the replenishment well, the water level in the well, and the diameter of the pipeline, the opening threshold of each fluid controller is calculated and set according to the empirical formula for pipeline flow. For example, if three replenishment branch pipelines are set around the replenishment well, the fluid controller on one of the replenishment branch pipelines will open immediately as soon as the water supply power unit is started. The flow rates corresponding to the opening of the fluid controllers on the other two replenishment branch pipelines are Q1 and Q2, respectively.

[0116] Specifically, by conducting constant flow recharge tests in similar wells within the same hydrogeological block, the actual recharge capacity at different well water levels was determined, and the water level-recharge capacity relationship curve was obtained as follows:

[0117] h = f(Qinj)

[0118] Where h is the depth of the dynamic water level in the well, in meters; Qinj is the steady-state recharge flow rate, in cubic meters per second. 3 / h; Design safety limit: hmin (e.g., 2 m from the wellhead, which is the highest permissible water level).

[0119] For the i-th feeder branch, the energy equation is as follows:

[0120] ΔPi = ρg(ΔHi) = [f·(Li / Di) + ΣKi] · (ρvi 2 / twenty one)

[0121] In the formula: ΔPi is the required driving pressure difference between the inlet and outlet of the replenishment branch pipeline, vi is the flow velocity corresponding to the flow rate Qi, vi = Qi / (πDi) 2 / 4); ΔHi is the corresponding head difference; f is the friction coefficient; Li is the length of the return branch pipe; Di is the diameter of the return branch pipe; ρ is the fluid density; Ki is the local loss coefficient.

[0122] Couple the well-to-pipe system:

[0123] Wellside: When the injection flow rate = Qi, the experimental curve gives hi = f(Qi);

[0124] Pipe side: Calculate the required driving head ΔHi under the same Qi using equation (1);

[0125] Let ΔHi = hi–z0 (z0 is the ground elevation, usually taken as 0), then Qi can be solved.

[0126] The following example uses three return branch lines:

[0127] The maximum replenishment capacity Qmax corresponds to hmin (2 m below the wellhead). Let the flow capacity of a single replenishment branch be qpipe (calculated from equation (1) when ΔHi = hmin), then:

[0128] Q1 = 1·qpipe (the upper limit of the first fluid controller operating alone);

[0129] Q2 = 2·qpipe (the upper limit of the first two fluid controllers in parallel);

[0130] Q3 = 3·qpipe ≤ Qmax;

[0131] The intelligent control center compares the real-time value Q of the flow detector with Q1 and Q2:

[0132] Q ≥ Q1 → Open valve 2

[0133] Q ≥ Q2 → Open valve 3

[0134] This ensures that: the water level in the well at any stage is ≤ hmin (safe); and each replenishment branch pipeline is always fully flowing and the inlet pressure is ≥ 0.02 MPa (positive pressure).

[0135] The above pipeline flow formula converts the test results of "well water level - flow rate" into the relationship of "pipeline pressure difference - flow rate", and solves in reverse the maximum flow rate qpipe that a single branch pipeline can withstand under the "safe water level". Then, the opening thresholds Q1 and Q2 of the solenoid valve are directly set as integer multiples of qpipe to keep the well water level in the safe range and maintain positive pressure full flow.

[0136] After determining the activation thresholds for each fluid controller and the target flow rate for each stage of variable flow, the variable flow compensation strategy is set as follows: the target flow rate for the first stage is q1 (q1 < Q1), the target flow rate for the second stage is q2 (Q1 < q2 < Q2), and the target flow rate for the third stage is q3 (Q2 < q3 < Qmax). Simultaneously, the compensation stage and target flow rate parameters in the compensation strategy are input to the intelligent control center.

[0137] The variable frequency drive starts the water supply power unit, initiating the first stage of replenishment. At this time, the fluid controller on the first replenishment branch line is turned on, while the fluid controllers on the second and third replenishment branch lines are turned off. As the speed of the water supply power unit gradually increases, the flow rate in the pipeline gradually increases. When the flow rate reaches q1, the speed of the water supply power unit remains stable. During this stage, if the real-time flow rate is greater than q1, the intelligent control center issues a command to reduce the speed of the water supply power unit; if the real-time flow rate is less than q1, the intelligent control center issues a command to increase the speed of the water supply power unit.

[0138] After the first stage ends, the second stage begins, gradually increasing the rotation speed of the water supply power unit. When the flow rate increases to Q1, the fluid controller on the second replenishment branch line is opened. At this time, the replenishment water flows into the replenishment well simultaneously along the first and second replenishment branch lines. When the replenishment flow rate reaches q2, the rotation speed of the water supply power unit remains stable. During this replenishment stage, if the real-time flow rate is greater than q2, the intelligent control center issues a command to reduce the rotation speed of the water supply power unit. If the real-time flow rate is less than q2, the intelligent control center issues a command to increase the rotation speed of the water supply power unit.

[0139] After the second stage, the third stage begins. At this time, the speed of the water supply power unit is gradually increased. When the flow rate increases to Q2, the fluid controller on the third replenishment branch line is opened. At this time, the replenishment water flows into the replenishment well simultaneously along the first, second, and third replenishment branch lines. When the replenishment flow rate reaches q3, the speed of the water supply power unit remains stable. During this replenishment stage, if the real-time flow rate is greater than q3, the intelligent control center issues a command to reduce the speed of the water supply power unit. If the real-time flow rate is less than q3, the intelligent control center issues a command to increase the speed of the water supply power unit.

[0140] After the third stage of replenishment is completed, the water supply power unit will automatically shut down, and the fluid controllers on the three replenishment branch pipelines will automatically shut down.

[0141] During replenishment operation, if a fault occurs that causes a sudden increase in pressure in the main replenishment pipeline, reaching the pipeline's limit, the pressure sensor will transmit the pressure value to the intelligent control center, which will then issue a shutdown command to the water supply power unit. If a fault occurs that causes the water level in the well to rise to a preset threshold (e.g., 2m) from the wellhead, the liquid level detector in the replenishment well will transmit the water level value to the intelligent control center, which will then issue a shutdown command to the water supply power unit. This effectively ensures the safety of the replenishment pipeline and prevents safety accidents caused by the overflow of replenishment water in the replenishment well.

[0142] If the fluid controller on a certain pipeline cannot be opened, in order to achieve the set replenishment flow rate, the program will gradually increase the speed of the water supply power unit and the pressure in the pipeline. When the pressure in the pipeline reaches the set pressure limit (pressure upper limit), the warning program will be activated, that is, the water supply power unit will be shut down, and a fault notification will be sent to the test site management personnel.

[0143] Determining the pressure limit requires comprehensive consideration of both the pressure tolerance of the surface pipeline and the pressure tolerance of the backfill branch pipeline. The pressure at the bottom of the backfill branch pipeline is equal to the sum of the pressure in the surface pipeline and the distance from the bottom of the branch pipeline to the ground. This upper pressure limit, Pmax, is determined according to the following principles:

[0144] Pmax = Ppipe - ρgh

[0145] Where Ppipe is the rated pressure of the ground pipeline and the replenishment branch pipeline, h is the depth of the replenishment branch pipeline outlet from the ground, and ρgh is the hydrostatic pressure at the outlet.

[0146] If the maximum pressure that both the surface pipeline and the replenishment branch pipeline can withstand is 1.5 MPa, and the bottom of the replenishment branch pipeline is 60 m above the ground (equivalent to a pressure of about 0.6 MPa), then the pressure limit of the surface pipeline needs to be set to 0.9 MPa. That is, when the fluid controller malfunctions and the pressure in the surface pipeline reaches 0.9 MPa, the water supply power unit needs to be shut down, and a fault signal should be sent to the test management personnel.

[0147] In summary, to effectively prevent the formation of waterfall flow, this invention utilizes the space above the filter layer outside the well casing of the replenishment well to lay multiple replenishment branch pipelines from the wellhead to the inside of the well. At the same time, it combines components such as fluid controllers, flow detectors, pressure sensors, liquid level detectors, water supply power devices, and intelligent control centers to realize intelligent positive pressure replenishment under variable flow conditions, effectively preventing gas blockage and the chemical and biological blockages it causes.

[0148] All the replenishment pipelines are buried in the water-stop clay ball section outside the well, without occupying the cross-sectional area of ​​the well. Compared with the "in-well pipe laying" scheme with the same replenishment capacity, the well diameter can be reduced from ≥φ400 mm to φ250 mm, and the well completion cost is reduced by 25-30%.

[0149] The intelligent control center activates the fluid controller in stages according to the preset target threshold of flow rate and adjusts the speed of the water supply power unit in real time to ensure that the main replenishment pipeline and each branch pipeline are always in a "full pipe + positive pressure" state; within 10–120 m 3 Within the range of / h, the pressure sensor reading remains >0.02 MPa to avoid non-full flow or negative pressure suction due to flow rate changes.

[0150] When the pressure of the main replenishment pipeline is greater than Pmax (which can be set to 0.9 MPa) or the water level in the well is less than 2 m from the wellhead, the intelligent control center can shut down the water supply power unit within 0.3 seconds to achieve unattended operation.

[0151] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. An intelligent variable flow positive pressure refill control system, characterized by, The application relates to a positive pressure variable flow recharge device for a recharge well. The device comprises: a plurality of recharge sub-pipes arranged in the space of the water-stopping clay balls above the filter layer outside the recharge well, one end of each recharge sub-pipe being in communication with the recharge well pipe and the other end being in communication with the external recharge main pipe, thereby forming independent positive recharge channels, wherein the positive recharge channels comprise at least a water supply power device; a flow control device comprising a control center, at least one pressure sensor, at least one flow detector and at least one fluid controller arranged on each positive recharge channel, wherein the control center is configured to control the corresponding number of positive recharge channels according to a preset recharge flow stage, to adapt the opening of each fluid controller and / or the power energy of the water supply power device, to realize positive pressure variable flow recharge; in addition, to set a multi-stage recharge flow threshold according to the recharge well capacity, to open the recharge sub-pipes in different numbers of positive recharge channels in stages, to control the rotating speed of the water supply power device to maintain the target flow; and to monitor the current data including flow, pressure and water level in real time, in the running process of any stage, if the real-time flow is higher than the target flow, the rotating speed of the water supply power device is reduced; if the real-time flow is lower than the target flow, the rotating speed of the water supply power device is increased; if the real-time pressure is greater than the preset upper limit of pressure or the water level in the well is less than the preset threshold from the well mouth, all fluid controllers are immediately cut off and the water supply power device is closed, to realize safe locking; wherein the water level data is collected from the liquid level detector in the recharge well; an automatic exhaust trigger device is arranged on the positive recharge channel, the automatic exhaust trigger device comprises an automatic exhaust device installed at the highest position of the pipe of the positive recharge channel, and the automatic exhaust device realizes switching between the ventilation state and the gas closing state, wherein when the recharge just starts, there is no water in the automatic exhaust device, and the automatic exhaust device is in the ventilation state; 2. The intelligent variable flow positive pressure refill control system of claim 1, wherein, with the water flow entering the pipe of the positive recharge channel, the gas in the pipe is gradually exhausted from the automatic exhaust device, and at the same time, the water in the pipe gradually rises, when rising into the automatic exhaust device, the floating ball in the automatic exhaust device blocks the exhaust port of the automatic exhaust device under the action of the buoyancy and water pressure, to enter the gas closing state, thereby realizing positive pressure recharge. The diameter and number of the recharge sub-pipes are determined according to the maximum recharge capacity of the recharge well and a pipe flow calculation model, the pipe flow calculation model adopts the Darcy-Weisbach formula for calculation: Delta P = f * (L / D) * (rho * v^2 / 2) + K * (rho * v^2 / 2), wherein Delta P is the required driving pressure difference between the inlet and the outlet of the recharge sub-pipe, f is a friction coefficient, L is the length of the recharge sub-pipe, D is the diameter of the recharge sub-pipe, rho is the fluid density, v is the flow rate, and K is a local loss coefficient; the recharge capacity of the well when the water level in the recharge well is stabilized near the well mouth is taken as the maximum recharge capacity Qmax, and the number of the recharge sub-pipes is obtained according to the maximum recharge capacity Qmax and the flow of a single recharge sub-pipe. ​ 3. The intelligent variable flow positive pressure refill control system of claim 1, wherein, The intelligent control center pre-stores at least three-stage variable flow positive pressure backfill strategies, and sequentially forms first-stage single pipe operation, second-stage double pipe parallel operation and third-stage multi-pipe operation along the flow increasing direction; when the actual flow Q exceeds the backfill flow threshold value of the corresponding stage, the next stage is automatically entered to maintain the well water level and full flow under positive pressure.

4. The intelligent variable flow positive pressure refill control system of claim 3, wherein, The first-stage single pipe operation only opens the fluid controller on the first positive backfill channel, takes the first target flow q1 as the set value, collects the actual flow Q in the positive backfill channel in real time, compares Q with the first target flow q1, adjusts the rotating speed of the water supply power device according to the comparison result, makes Q=q1, and keeps the pipeline positive pressure, so as to realize low flow accurate backfill.

5. The intelligent variable flow positive pressure refill control system of claim 4, wherein, When Q≥Q1, the second-stage double pipe parallel operation is entered, the fluid controller on the second positive backfill channel is opened, the second target flow q2 is taken as the set value, the actual total flow in the two positive backfill channels is collected in real time, the actual total flow is compared with the second target flow q2, the rotating speed of the water supply power device is adjusted according to the comparison result, the actual total flow=q2 is made, and the pipeline positive pressure is kept; wherein q2>q1, Q1 is the first-stage backfill flow threshold value set according to the backfill well capacity.

6. The intelligent variable flow positive pressure refill control system of claim 5, wherein, When Q≥Q2, the third-stage multi-pipe operation is entered, the fluid controller on the third positive backfill channel is opened, the third target flow q3 is taken as the set value, the actual total flow in the positive backfill channel participating in backfill is collected in real time, the actual total flow is compared with the third target flow q3, the rotating speed of the water supply power device is adjusted according to the comparison result, the actual total flow=q3 is made, and the pipeline positive pressure is kept; wherein q2<q3≤Qmax, Qmax is the maximum backfill capacity of the well corresponding to the limit water level near the well mouth; Q2 is the second-stage backfill flow threshold value set according to the backfill well capacity, Q2>Q1.

7. A method for applying the intelligent variable flow positive pressure backfill control system according to any one of claims 1-6, characterized in that, The method comprises the following steps: S1: based on the maximum backfill capacity Qmax of the backfill well, the stable water level in the well and the backfill branch pipeline parameters, the Darcy-Weisbach formula considering the along-path and local head loss is adopted to pre-calculate and set the backfill flow threshold values Q1, Q2,..., Qn-1 of each stage and the target flows q1, q2,..., qn of each stage; S2: the backfill flow threshold values and the target flows are written into the intelligent control center, the water supply power device is started, and the multi-stage backfill is executed according to the following sub-steps: S2-1: first stage: only open the fluid controller in the first positive backfill channel, adjust the rotating speed of the water supply power device to make the flow detector stable at q1; S2-2: second stage: when the flow increases to Q1, open the fluid controller in the second positive backfill channel, continue to adjust the water supply power device to make the flow stable at q2; S2-3: similarly, open the fluid controller in the nth positive backfill channel in the nth stage to make the flow stable at qn; S3: in each stage, if the real-time flow is higher than the target flow, the rotating speed of the water supply power device is reduced; if the real-time flow is lower than the target flow, the rotating speed of the water supply power device is increased; S4: When the n-th stage of backfilling is completed, the intelligent control center closes the water supply power device and all fluid controllers; S5: During operation, if the pressure sensor detects that the backfilling main pipeline pressure exceeds the upper limit of the pressure or the liquid level detector detects that the water level in the well is less than the preset threshold from the wellhead, the intelligent control center immediately executes the water stop protection and alarms.

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