Agent delivery device for groundwater remediation and method thereof

Abstract

The application belongs to the technical field of groundwater remediation, and specifically discloses a medicament feeding device for groundwater remediation and a method thereof. The medicament feeding device comprises a well pipe unit and a treatment unit. The well pipe unit comprises a main well pipe and downhole pipes and uphole pipes arranged in a circumferential direction. The treatment unit comprises a sleeve, double blocking members, a plunger pump body and a medicament feeding nozzle, and a closed mixing cavity is formed in the sleeve. The application sets the height difference between the downhole pipes and the uphole pipes and the hydraulic gradient according to the stratigraphic permeability coefficient, drives the forced circulation of the groundwater by the plunger pump, and recirculates the stratum after the medicament is fully mixed with the groundwater in the sleeve. The application does not rely on the natural flow of the groundwater, and can avoid the accumulation, short circuit and cross-layer pollution of the medicament. The application has small stratum disturbance, high remediation efficiency and strong engineering implementation, can accurately adapt to various permeability characteristic pollution aquifers, and especially solves the remediation problem of low-flow groundwater layers, and realizes layered accurate and efficient remediation.

Description

Technical Field

[0001] This invention belongs to the field of groundwater remediation technology, and specifically relates to a groundwater remediation agent delivery device and method. Background Technology

[0002] With the rapid advancement of industrialization and urbanization, problems such as industrial wastewater leakage, leachate infiltration from solid waste landfills, agricultural non-point source pollution, and chemical raw material leakage have become increasingly prominent. A large amount of pollutants continue to seep into underground aquifers, causing serious groundwater pollution. Among these, low-flow-rate groundwater layers have become the core pain point in groundwater pollution control due to the difficulty in remediation.

[0003] Low-flow-rate groundwater layers have small pores, poor connectivity, and extremely low natural hydraulic gradients. Groundwater flows almost freely without direction, making it easy for pollutants to accumulate and concentrate in the pores after entering these layers, hindering their natural diffusion. Existing groundwater remediation agent application technologies are mainly divided into three categories: in-situ passive injection technology, in-situ active high-pressure injection technology, and groundwater circulation well technology. All three technologies have significant drawbacks in practical applications. Firstly, there is the in-situ passive injection technology. This type of technology mostly involves in-situ passive injection, relying on the natural flow of groundwater to drive the diffusion of the reagent. In practical use, the device relies on the natural flow of groundwater to operate. Specifically, Chinese patent CN120172475B discloses a reagent delivery device for groundwater remediation, and Chinese patent CN117049687B discloses an in-situ groundwater remediation system for landfills. In low-flow-rate groundwater layers, because the groundwater cannot provide sufficient power, the reagent cannot diffuse to the contaminated area, easily accumulating near the injection port and forming a remediation blind zone, causing the device to lose its actual remediation capability.

[0004] Secondly, there is the in-situ active high-pressure injection technology. While this technology increases diffusion speed through forced injection of chemicals under high pressure, it causes severe disturbance to the formation and carries high engineering risks. Specifically, Chinese patent CN105964678B proposes an in-situ injection system and method for soil and groundwater remediation—high-pressure jet grouting—and Chinese patent CN206981419U proposes a high-pressure injection drill rod device for in-situ remediation of soil and groundwater pollution. Both of these devices employ forced injection under high pressure. High-pressure jet grouting severely damages the original formation structure, easily leading to formation collapse; the range of jet grouting is uncontrollable, and the chemical distribution is uneven; simultaneously, energy consumption is extremely high, and engineering implementation is difficult.

[0005] Thirdly, groundwater circulation well technology. This type of technology constructs forced circulation of groundwater through extraction and reinjection, which overcomes the problem of insufficient natural flow to some extent, but still cannot achieve precise stratified remediation and uniform diffusion of agents. Specifically, Chinese patent with authorization announcement number CN116514210B uses funnel internals and a packing bed to achieve groundwater circulation treatment, relying solely on the liquid level difference to drive water flow circulation. In low-permeability strata, the water flow driving force is insufficient, and the agent diffusion range is limited. Chinese patent with publication number CN119870131A uses well group linkage and pneumatic drive to construct a three-dimensional hydraulic circulation, relying on the water level difference between wells to drive agent migration. The agent tends to migrate rapidly along the dominant channels, resulting in problems such as uneven diffusion, local enrichment, and remediation blind spots.

[0006] In summary, none of the three existing technologies can simultaneously meet the comprehensive requirements of low-flow-rate aquifers, namely, "not relying on natural flow, minimal formation disturbance, uniform reagent diffusion, no cross-layer contamination, and precise and efficient remediation." To address these common shortcomings, there is an urgent need to develop a reagent delivery device and method specifically for low-flow-rate groundwater aquifers. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a groundwater remediation agent delivery device and method that are suitable for the remediation needs of low-flow-rate groundwater layers. Furthermore, by employing a well pipe height difference and hydraulic gradient grading design based on formation permeability characteristics, it achieves an optimal balance between agent diffusion efficiency and pollutant reaction time. Combined with quantitative matching of pump parameters and hydraulic gradient, it precisely controls water flow velocity, ultimately achieving efficient and precise stratified remediation of groundwater.

[0008] The technical solution of the present invention is: a groundwater remediation agent dosing device, comprising a well pipe unit and a processing unit.

[0009] The well casing unit includes a first well casing, multiple second well casings, and multiple third well casings. The first well casing is installed inside a vertical shaft. Multiple second well casings are arranged around the first well casing along its axis, with one end of each second well casing connected to the first well casing. Multiple third well casings are arranged around the first well casing along its axis, with each third well casing located above the second well casings, and one end of each third well casing connected to the first well casing.

[0010] The processing unit includes a sleeve, a sealing component, a pump body, and a dosing nozzle.

[0011] The sleeve is a cylindrical structure closed at one end and open at the other. Its opening faces downwards and is vertically installed inside the first well pipe. The opening of the sleeve is located between the second and third well pipes. A discharge groove is formed on the side wall of the sleeve, located above the third well pipe. The sealing components include a first sealing component and a second sealing component. The first sealing component is fixed between the sleeve and the first well pipe, located at the sleeve opening; the second sealing component is fixed between the sleeve and the first well pipe, located above the discharge groove. The pump body is installed inside the sleeve, below the discharge groove. When the pump body is running, it allows groundwater to enter the first well pipe from the second well pipe, then enter the sleeve through the sleeve opening, then be discharged through the discharge groove, and finally enter the third well pipe from the first well pipe and be discharged from the third well pipe. The height difference Δh between the second and third well pipes is determined according to the permeability coefficient of the contaminated aquifer, with 1m ≤ Δh ≤ 6m. The dosing nozzle is fixed inside the sleeve, located above the pump body, and connected to an external dosing device. It is used to dispense the remediation agent into the sleeve. The remediation agent mixes with the groundwater inside the sleeve before the groundwater is discharged through the outlet channel.

[0012] Furthermore, the specific value of the height difference Δh between the second and third well casings is: When the stratum permeability coefficient K>10 -2 When the flow rate is cm / s, 1m≤Δh≤2m; such permeable strata include pebble layers and karst fissure water layers. These strata have large pores and good connectivity, and the resistance to groundwater flow is extremely small. Only a small height difference is needed to form a seepage velocity that meets the remediation requirements. If the height difference is too large, the groundwater flow velocity will be too fast, and the reagent will be quickly carried away as soon as it is added, without enough time to react with the pollutants, causing the reagent to short-circuit. At the same time, it will also increase the geological risks of piping and collapse in the strata and increase the energy consumption of the pump.

[0013] When the stratum permeability coefficient is 10 -4 cm / s≤K≤10 -2 When the flow rate is cm / s, 2m < Δh ≤ 4m; such permeable strata are silt layers and fine sand layers. The permeability resistance of such strata is moderate. Appropriately increasing the height difference can achieve a balance between reagent diffusion efficiency and reaction time, ensuring that the reagent can diffuse to the entire contaminated area and fully contact and react with the pollutants.

[0014] When the formation permeability coefficient K < 10 -4 When the flow rate is 4 m < Δh ≤ 6 m, this type of permeable stratum includes clay and silt layers. These strata have small pores and poor connectivity, resulting in extremely high resistance to groundwater flow. A significant height difference is required to create a sufficient hydraulic gradient to overcome the stratum resistance and achieve effective seepage. If the height difference is too small, the groundwater flow rate will be too slow, and the reagent will accumulate near the dosing point, failing to diffuse to the entire contaminated area and creating a remediation blind zone. However, these strata have higher shear strength, and a larger height difference will not cause stratum instability. This is a necessary price to pay for achieving effective remediation.

[0015] The height difference Δh between the second and third well casings is the vertical installation spacing between the two well casings. It is the core structural parameter for constructing an artificial hydraulic gradient. Its value range is 1m≤Δh≤6m, and it needs to be designed in stages according to the permeability coefficient of the contaminated aquifer. The core design logic is: by matching the permeability characteristics of different strata, construct the optimal hydraulic gradient that meets the requirements of reagent diffusion and ensures sufficient reaction time for pollutants, so as to avoid a decrease in remediation efficiency due to excessively large or small height differences.

[0016] Furthermore, the hydraulic gradient i between the second and third well pipes is graded according to the formation permeability characteristics. The hydraulic gradient i between the second and third well pipes is the ratio of the height difference Δh to the vertical flow path length between them, i.e., i = Δh / L, where L represents the actual path length of the groundwater vertical flow in the contaminated aquifer. In this invention, L = Δh = H is assumed to be true. p Therefore, i = Δh / H p The hydraulic gradient *i* is a core indicator characterizing the "driving force" of artificially driven groundwater flow. The value of *i* needs to be matched with the classification of formation permeability characteristics, specifically: When the stratum permeability coefficient K>10 -2 When the velocity is 10 cm / s, 0.05 ≤ i ≤ 0.1; when the stratum permeability coefficient is 10 -4 cm / s≤K≤10 - 2 When the velocity is 10 cm / s, 0.1 < i ≤ 0.2; when the stratum permeability coefficient K < 10 -4 When the speed is cm / s, 0.2 < i ≤ 0.3.

[0017] The graded values ​​of the hydraulic gradient correspond one-to-one with the graded design of the height difference. Essentially, this utilizes Darcy's law to control the seepage velocity v within the optimal range: ensuring the reagent diffuses throughout the contaminated area with the water flow while preventing excessive flow velocity from causing short-circuiting, thus balancing formation stability and engineering economics. Low-permeability formations require a high hydraulic gradient of 0.2–0.3 to overcome formation resistance and achieve an effective flow velocity; medium-permeability formations use a moderate hydraulic gradient of 0.1–0.2 to achieve a balance between diffusion and reaction; high-permeability formations only require a low hydraulic gradient of 0.05–0.1 to meet remediation needs while avoiding excessive flow velocity and geological risks.

[0018] Furthermore, the pump body includes a pump barrel and a plunger. The pump barrel is a cylindrical structure with openings at both ends, coaxially distributed with a sleeve and located inside the sleeve. The outer side wall of one opening of the pump barrel is fixed to the inner side wall of the opening of the sleeve. This opening of the pump barrel has a first moving valve chamber, in which a first moving valve ball is disposed. The first moving valve ball and the first moving valve chamber constitute a first moving valve. The other opening of the pump barrel is located below the discharge slot. The plunger is slidably disposed inside the pump barrel. One end of the plunger is connected to a drive rod, which is connected to an external drive device to drive the plunger to perform piston movement inside the pump barrel. The plunger has a channel penetrating the plunger along its axis. The side of the channel near the first moving valve ball has a second moving valve chamber, in which a second moving valve ball is disposed. The second moving valve ball and the second moving valve chamber constitute a second moving valve.

[0019] When the drive rod moves the plunger upward inside the pump barrel, the first moving valve is in the open state and the second moving valve is in the closed state; when the drive rod moves the plunger downward inside the pump barrel, the first moving valve is in the closed state and the second moving valve is in the open state.

[0020] Furthermore, the piston movement frequency f is based on the formula... The calculation involves the following parameters: d represents the plunger diameter; s represents the plunger's stroke; K represents the formation permeability coefficient; η represents the pump's volumetric efficiency, ranging from 0.8 to 0.95; i represents the hydraulic gradient between the second and third well pipes; and A represents the effective vertical flow area, i.e., the cross-sectional area of ​​the formation actually involved in seepage when groundwater flows vertically between the second and third well pipes. Pump operating parameters can be calculated back from the target hydraulic gradient, achieving precise matching between pump power and the hydraulic gradient, ensuring the stable formation of the artificial hydraulic gradient.

[0021] Furthermore, the effective water flow area A of the vertical water flow is determined according to formula... Calculate; where, B represents the actual thickness of the contaminated aquifer, and B represents the effective influence width of the well group, which is the range in which the second and third well pipes can drive water flow in the horizontal direction. The value ranges from 5m to 20m, with smaller values ​​for low-permeability formations and larger values ​​for high-permeability formations.

[0022] Furthermore, the second well pipe has the same structure as the third well pipe, which is a pipe body structure, with the end away from the first well pipe closed, and multiple through holes evenly opened on the pipe wall.

[0023] Furthermore, the density of the through holes gradually increases from the side closest to the first well casing towards the side furthest away from it. This structure prevents groundwater from concentrating near the well casing, expanding the extraction and reinjection range of groundwater and increasing the contact area with the formation.

[0024] A method for administering chemicals for groundwater remediation, comprising the following steps using the chemical administration device: The drilling process forms a vertical shaft, and the first well casing is lowered in. Secondary drilling is then performed by side-drilling at corresponding depths in the second and third well casings, followed by the lowering of the second and third well casings. A sleeve containing a pump and a chemical dosing nozzle is placed inside the first well casing, and the first and second sealing components are sequentially inserted. The chemical dosing nozzle is then connected to an external chemical supply device. The pump is activated, and groundwater from the second well casing enters the first well casing and then flows into the sleeve through the opening. The chemical dosing nozzle delivers remediation agents that mix with the groundwater, which are then discharged through a drain trough. The mixture then flows from the first well casing into the third well casing and into the formation at the third well casing. During this process, a stable hydraulic gradient is formed between the second and third well casings, driving the flow of the groundwater containing the remediation agents.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention completely overcomes the defect of in-situ passive injection technology that relies on the natural flow of groundwater. It constructs artificial forced water circulation through "second well pipe extraction, third well pipe reinjection, and pump body active drive", without relying on natural hydraulic conditions, and fundamentally solves the industry pain points of low-flowability formation agents having no power to diffuse, easy to silt up, and large repair blind areas.

[0026] This invention effectively avoids the problems of formation damage and severe disturbance caused by in-situ active high-pressure injection technology. It does not use high-pressure jet grouting and forced injection, but relies solely on controllable hydraulic circulation to achieve agent diffusion. Formation disturbance is small, and there is no risk of fracturing and collapse. The safety, stability and feasibility of the project are significantly improved.

[0027] This invention comprehensively overcomes the shortcomings of existing groundwater circulation well technology, which lacks stratified design and precise hydraulic control. By using a stratified design based on the height difference Δh of the formation permeability coefficient and the hydraulic gradient i, combined with a sleeve-sealed mixing structure, it achieves uniform mixing and precise diffusion of the agent, effectively avoiding agent short-circuiting, cross-flow and cross-layer contamination, and significantly improving remediation efficiency and coverage.

[0028] This invention achieves integrated in-situ operation of groundwater extraction, chemical dosing, mixing, and reinjection through layered well pipe layout, double-sealing components, and coaxial integrated structure. It features a compact structure, simple construction, minimal disturbance to the surface environment, and can be adapted to aquifers with high, medium, and low permeability characteristics, making it more widely applicable and providing more precise and efficient repair. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is the present invention. Figure 2Enlarged view of the structure at point A; Figure 4 This is a partial flow diagram of groundwater within the device of the present invention.

[0030] Among them, 1-first well casing, 2-second well casing, 3-third well casing, 4-sleeve, 40-outlet groove, 5-plugging component, 51-first plugging component, 52-second plugging component, 6-pump body, 61-pump barrel, 610-first moving valve chamber, 611-first moving valve ball, 62-plunger, 621-drive rod, 622-channel, 623-second moving valve chamber, 624-second moving valve ball, 7-drug dosing nozzle. Detailed Implementation

[0031] The following is combined Figures 1 to 4 The specific embodiments of the present invention will be described in detail below. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] Example like Figure 1 , Figure 2 The device shown is a groundwater remediation agent delivery device, which includes a well pipe unit and a treatment unit.

[0034] The well casing unit includes a first well casing 1, multiple second well casings 2, and multiple third well casings 3. The first well casing 1 is installed inside the vertical shaft. The multiple second well casings 2 are arranged around the first well casing 1 along its pipe axis, and one end of each second well casing 2 is connected to the first well casing 1. The multiple third well casings 3 are arranged around the first well casing 1 along its pipe axis, and the third well casings 3 are located above the second well casings 2, with one end of each third well casing 3 connected to the first well casing 1.

[0035] The processing unit includes a sleeve 4, a sealing component 5, a pump body 6, and a dosing nozzle 7.

[0036] The sleeve 4 is a cylindrical structure that is closed at one end and open at the other. Its opening faces downward and is vertically installed inside the first well pipe 1. The opening of the sleeve 4 is located between the second well pipe 2 and the third well pipe 3. A drain groove 40 is provided on the side wall of the sleeve 4, and the drain groove 40 is located above the third well pipe 3. The sealing component 5 includes a first sealing component 51 and a second sealing component 52. The first sealing component 51 is fixed between the sleeve 4 and the first well pipe 1 and is located at the opening of the sleeve 4; the second sealing component 52 is fixed between the sleeve 4 and the first well pipe 1 and is located above the drain groove 40. Pump body 6 is installed inside sleeve 4, below discharge channel 40. When pump body 6 is running, it is used to allow groundwater to enter first well pipe 1 from second well pipe 2, then enter sleeve 4 through the opening of sleeve 4, and then be discharged through discharge channel 40. The groundwater then enters third well pipe 3 from first well pipe 1 and is discharged from third well pipe 3. The height difference Δh between second well pipe 2 and third well pipe 3 is determined according to the permeability coefficient of the contaminated aquifer, with 1m ≤ Δh ≤ 6m. Dosing nozzle 7 is fixed inside sleeve 4, above pump body 6, and connected to an external dosing device. It is used to dispense remediation agents into sleeve 4. The remediation agents mix with the groundwater inside sleeve 4 before being discharged through discharge channel 40.

[0037] Existing in-situ passive chemical injection technology relies entirely on the natural flow of groundwater to drive the diffusion of the agent, which completely fails in low-flow-rate groundwater layers due to the lack of effective driving force. This embodiment constructs an artificially forced water circulation path through the core structural design of "extraction from the second well pipe 2, reinjection from the third well pipe 3, and active driving by the pump body 6": when the pump body 6 is running, it directly drives the groundwater from the lower second well pipe 2 into the first well pipe 1, mixes the agent through the sleeve 4, and then reinjects it into the formation from the upper third well pipe 3. It does not rely on the natural hydraulic conditions of groundwater, and structurally solves the problem of the lack of driving force for agent diffusion in low-flow-rate formations. This allows the device to be directly applied to low-flow-rate groundwater layers such as clay and silt layers, which are not suitable for traditional technologies, filling the technical gap for in-situ remediation of such formations.

[0038] The dosing nozzle 7 is precisely positioned above the pump body 6 inside the sleeve 4, and the sleeve 4, together with the first sealing component 51 and the second sealing component 52, forms a closed mixing chamber. Groundwater flows upwards directionally along the sleeve 4 under the drive of the pump body 6. The dosing nozzle 7 precisely adds the remediation agent to the flowing groundwater. As the groundwater flows from the pump body 6 to the discharge trough 40, it undergoes pre-mixing and dynamic mixing with the agent within the sleeve 4 before being discharged through the discharge trough 40 and reinjected into the formation. This structure ensures that the agent and groundwater form a homogeneous mixture before entering the formation, preventing agent accumulation in the formation and significantly improving the initial contact efficiency between the agent and pollutants in the formation, thereby enhancing the reaction efficiency of groundwater remediation from the source.

[0039] Existing active high-pressure chemical injection technology suffers from problems such as uncontrollable chemical diffusion range, easy flow bypassing the core contaminated area, and potential cross-layer contamination. This embodiment utilizes layered well casing and the sealing cooperation of the sleeve 4 and double sealing components to form a directional, closed water circulation and chemical diffusion path. Specifically, the second well casing 2 and the third well casing 3 are arranged vertically in layers, corresponding to the lower and upper parts of the contaminated aquifer, respectively, ensuring that water circulation occurs only within the contaminated aquifer. The first sealing component 51 seals the gap between the opening of the sleeve 4 and the first well casing 1, and the second sealing component 52 seals the gap above the outlet groove 40. Figure 4 As shown, the forced groundwater flow is restricted to a predetermined path: "Second Well Pipe 2 → First Well Pipe 1 → Sleeve 4 → Outlet Channel 40 → First Well Pipe 1 → Third Well Pipe 3," preventing disorderly flow of groundwater within the well pipes. This structure ensures that the groundwater containing the mixed chemicals can be precisely reinjected into the contaminated aquifer, diffusing vertically from top to bottom. This prevents the chemicals from flowing around the core contaminated area and also prevents the remediation water flow from interfering with the clean aquifer, structurally eliminating the problem of cross-layer contamination.

[0040] Multiple second well pipes 2 and multiple third well pipes 3 are evenly arranged around the circumference of the first well pipe 1, so that the stratified extraction of groundwater and the reinjection of chemicals can be achieved simultaneously in the annular area around the first well pipe 1. Compared with the traditional single-pipe structure, the horizontal coverage of the device to the contaminated strata is greatly expanded, and the remediation agent can be more evenly diffused to the contaminated area around the first well pipe 1, effectively reducing the remediation blind zone and improving the comprehensiveness of groundwater remediation.

[0041] The treatment unit and the well casing unit are coaxially arranged, with all core functional components integrated inside the first well casing 1, resulting in a compact overall structure. During construction, only a single vertical shaft and horizontal branch well casings need to be drilled, eliminating the need for large-scale excavation or the deployment of external equipment. This minimizes disturbance to surface buildings and the ecological environment, making it suitable for construction in areas with complex surface environments such as urban built-up areas and industrial sites. It also reduces the engineering costs of drilling and equipment installation, significantly improving the feasibility and marketability of the device. The four core functions—groundwater extraction, chemical dosing, chemical mixing with groundwater, and mixed solution reinjection—are integrated into a single device. The entire process is achieved through a single power source, pump 6, eliminating the need to pump groundwater to the surface for off-site treatment. This eliminates the need for surface water treatment equipment and separate chemical dosing pipes, greatly simplifying the groundwater remediation process, reducing equipment investment and operating energy consumption, and truly achieving the design goal of in-situ groundwater remediation and integrated operation.

[0042] The height difference Δh between the second well casing 2 and the third well casing 3 is a core parameter for constructing an artificial vertical hydraulic gradient, achieving directional diffusion of reagents, and ensuring sufficient reaction of pollutants. Its design needs to comprehensively consider factors such as formation permeability characteristics, reagent reaction kinetics, formation stability, and remediation efficiency. The specific design basis is as follows: Hydrogeological constraints: The permeability coefficient of the poorly mobile groundwater layer is extremely low, K<10. -4 For pore water layers and weakly permeable layers, a stable hydraulic gradient needs to be formed through a sufficient height difference to drive the vertical flow of groundwater and spread the remediation agent to the contaminated area; at the same time, the height difference must not exceed the formation's collapse resistance limit to avoid formation instability caused by a sudden drop in pore water pressure.

[0043] Reaction kinetic constraints: The height difference must match the reaction half-life of the remediation agent and the pollutants to ensure that the residence time of groundwater in the vertical flow path is not less than the effective reaction time of the agent, so as to ensure that the pollutants are fully degraded and to avoid the agent passing through the contaminated area quickly with the water flow without completing the reaction.

[0044] Restoration efficiency and engineering feasibility constraints: The height difference needs to take into account both the diffusion range of the agent and the energy consumption of the pump. An excessively large height difference will increase the pump head burden and the risk of ground damage, while an excessively small height difference will not be able to form an effective hydraulic gradient, resulting in the agent accumulating in the dosing area and limiting the restoration range.

[0045] The height difference Δh between the second well casing 2 and the third well casing 3 is expressed by the formula... Calculate; where, This indicates the maximum allowable height difference for formation stability. This indicates the maximum allowable height difference in the drug reaction kinetics. This indicates the actual thickness of the polluted aquifer.

[0046] The maximum allowable height difference for formation stability is calculated using Terzaghi's effective stress principle, specifically by formula... Calculate; where, Indicates the effective unit weight of the soil in the stratum, kN / m 3 For sandy soil, the value is 9-11; for clay, the value is 7-9; H represents the burial depth of the second well casing 2, in meters; represents the unit weight of water. Take 9.81 kN / m 3 .

[0047] The maximum allowable height difference in the reaction kinetics of the reagent is calculated using Terzaghi's effective stress principle, specifically by formula... Calculate; where, This represents the vertical flow path length between the second well pipe 2 and the third well pipe 3, which is approximately equal to the thickness of the contamination layer; The permeability coefficient m / d of the contaminated aquifer is determined by hydrogeological survey; n represents the safety factor, which is 3 to 5, ensuring that the residence time is 3 to 5 times the half-life of the reagent. The half-life (d) represents the reaction between the remediation agent and the target pollutant.

[0048] Furthermore, to ensure the artificial hydraulic gradient and reagent diffusion efficiency, the following must be met: , ; i represents the hydraulic gradient, taken as 0.2–0.3 for low-permeability formations, 0.1–0.2 for medium-permeability formations, and 0.05–0.1 for high-permeability formations; v represents the vertical seepage velocity of groundwater, in m / d, which must meet the requirements of the reagent residence time. .

[0049] Therefore, considering the permeability characteristics of different formations and the repair requirements, the recommended range for the height difference Δh between the second well casing 2 and the third well casing 3 is as follows: When the stratum permeability coefficient K>10 -2 When the velocity is cm / s, 1m ≤ Δh ≤ 2m; when the stratum permeability coefficient is 10 -4 cm / s≤K≤10 - 2 When the velocity is cm / s, 2m < Δh ≤ 4m; when the stratum permeability coefficient K < 10 -4 When the speed is cm / s, 4m < Δh ≤ 6m.

[0050] For formations with different permeability characteristics, groundwater flow resistance and seepage patterns vary significantly, and a single height difference cannot meet the hydraulic drive requirements of all formations. Dividing the height difference Δh into three levels according to the formation permeability coefficient essentially allows the hydraulic gradient created by the height difference to be inversely adapted to the formation permeability coefficient: high-permeability formations have low resistance, so a small height difference is used to create a low gradient to avoid excessive flow velocity; low-permeability / low-flow formations have high resistance, so a large height difference is used to create a high gradient to overcome resistance and achieve effective seepage. This design upgrades the height difference from a "generalized standardized parameter" to a "formation-customized parameter," ensuring that the device can construct an artificial hydraulic gradient adapted to the formation characteristics in contaminated aquifers with any permeability characteristics, guaranteeing the effectiveness of hydraulic drive from the parameter source.

[0051] The core objective of remediation is to ensure that the reagent can both diffuse throughout the contaminated area and fully react with the pollutants. Water flow velocity is a key factor determining this balance, and it is determined by both the permeability coefficient and the hydraulic gradient, based on Darcy's law v=K・i. Through precise control of elevation differences, the groundwater flow velocity in different strata is strictly controlled within the optimal remediation range. When the stratum permeability coefficient K>10 -2 When the flow rate is cm / s, 1m≤Δh≤2m; a low hydraulic gradient is formed to avoid excessive flow velocity due to excessive K, and to prevent the reagent from being carried away by the water flow immediately after addition, thus ensuring sufficient reaction time between the reagent and the pollutants.

[0052] When the stratum permeability coefficient is 10 -4 cm / s≤K≤10 -2When the flow rate is cm / s, 2m < Δh ≤ 4m; a high hydraulic gradient is formed to overcome the high resistance of the formation and ensure that the water flow velocity is sufficient to drive the agent to diffuse to the entire contaminated area, avoiding the agent from accumulating around the well pipe and forming a blind spot for remediation.

[0053] When the formation permeability coefficient K < 10 -4 When the flow rate is cm / s, 4m < Δh ≤ 6m; a moderate hydraulic gradient is formed, achieving a precise balance between the reagent diffusion range and the reaction time.

[0054] It completely solves the problem of "low repair efficiency in some formations due to a single parameter", allowing the repair effect of various formations to reach the optimal level.

[0055] Furthermore, the geological characteristics and engineering risks of different permeable strata vary significantly. A tiered height difference design can specifically mitigate the unique engineering risks of each stratum, providing safety assurance for the equipment's operation from a parameter perspective: High-permeability strata are mostly loose sand and gravel layers with poor impermeability and a high risk of piping. A small height difference of 1m to 2m can control the head difference within a safe range, avoiding geological disasters such as piping, stratum collapse, and sand liquefaction caused by excessive head difference. Low-permeability strata are mostly dense clay and silt layers with high shear strength and good stratum stability, capable of withstanding greater head differences. Therefore, a large height difference of 4m to 6m is adopted, which neither causes stratum instability nor fails to meet the hydraulic drive requirements, achieving a balance between safety and efficiency. Medium-permeability strata have moderate geological characteristics; a height difference of 2m to 4m can match their stratum stability threshold while meeting seepage drive requirements, avoiding risks and energy waste caused by over-design.

[0056] Preferably, the hydraulic gradient i between the second well casing 2 and the third well casing 3 is determined according to the formation permeability characteristics, specifically as follows: When the stratum permeability coefficient K>10 -2 When the velocity is 10 cm / s, 0.05 ≤ i ≤ 0.1; when the stratum permeability coefficient is 10 -4 cm / s≤K≤10 - 2 When the velocity is 10 cm / s, 0.1 < i ≤ 0.2; when the stratum permeability coefficient K < 10 -4 When the speed is cm / s, 0.2 < i ≤ 0.3.

[0057] The hydraulic gradient is a core dynamic indicator determining groundwater flow velocity and is directly related to the height difference Δh, i.e., i = Δh / L. Due to the hierarchical matching of height difference and formation permeability coefficient, further hierarchical values ​​of the hydraulic gradient based on formation permeability characteristics allow for a one-to-one linkage between the hydraulic gradient, height difference, and formation permeability coefficient. This design standardizes and hierarchically classifies all core parameters of artificial hydraulic actuation, upgrading the device from "hydraulic actuation solely based on structure and height difference" to "a standardized artificial hydraulic actuation system based on groundwater dynamics." This ensures that in any permeable stratum, an optimal hydraulic actuation system adapted to the stratum's characteristics can be constructed through the dual constraints of height difference and hydraulic gradient, guaranteeing the effectiveness of water flow and reagent diffusion from a dynamic perspective.

[0058] Existing technologies cannot quantitatively control the flow velocity of artificially driven groundwater, which can easily lead to problems such as low remediation efficiency due to excessively fast or slow flow velocities. However, according to Darcy's law, the groundwater flow velocity is determined by both the formation permeability coefficient and the hydraulic gradient. The formation permeability coefficient has been clearly classified, and the hydraulic gradient has been further quantitatively classified and limited, which is equivalent to directly setting precise flow velocity control thresholds for different formations.

[0059] When the stratum permeability coefficient K>10 -2 When the flow rate is cm / s, 0.05≤i≤0.1; by quantitatively limiting i, we can avoid K from being too large and causing flow rate runaway, and accurately control the flow rate within the range of "ensuring the reaction time of the reagent" to prevent reagent short circuit.

[0060] When the stratum permeability coefficient is 10 -4 cm / s≤K≤10 -2 When the flow rate is cm / s, 0.1 < i ≤ 0.2; by quantitatively limiting i, it is ensured that the high resistance of the formation can be overcome, and the flow velocity can be precisely controlled at the effective threshold of "driving the diffusion of the agent throughout the entire range", thus avoiding the accumulation of the agent.

[0061] When the formation permeability coefficient K < 10 -4 When the flow rate is cm / s, 0.2 < i ≤ 0.3; control the flow rate within the optimal range of "diffusion efficiency and reaction time balance".

[0062] This design enables quantitative design and controllable operation of groundwater flow velocity, completely solving the remediation problem caused by uncontrolled flow velocity, and making the remediation effect of various strata predictable and controllable.

[0063] Since pump body 6 is the power source for the artificial hydraulic gradient, the design of its operating parameters, such as plunger diameter, stroke, and movement frequency, must be based on the target hydraulic gradient. The quantitative classification of hydraulic gradient i provides clear and unified core dynamic indicators for the calculation of pump body operating parameters, upgrading the design of pump body 6 parameters from empirical selection to quantitative calculation. For different formations, the movement frequency, diameter, and other parameters of the plunger of pump body 6 can be accurately calculated directly from the corresponding hydraulic gradient target value, combined with formation parameters and water flow area, ensuring that the output power of the pump body is fully matched with the hydraulic gradient requirements of the formation. This avoids the problem of insufficient pump power to form the target hydraulic gradient and also prevents energy waste and equipment damage caused by excess power, achieving precise matching between power supply and hydraulic demand.

[0064] Preferred, such as Figure 3 As shown, the pump body 6 includes a pump barrel 61 and a plunger 62. The pump barrel 61 is a cylindrical structure with openings at both ends. The pump barrel 61 is coaxially distributed with the sleeve 4 and located inside the sleeve 4. The outer side wall of one of the openings of the pump barrel 61 is fixed to the inner side wall of the opening of the sleeve 4. The opening of the pump barrel 61 has a first moving valve chamber 610. A first moving valve ball 611 is provided in the first moving valve chamber 610. The first moving valve ball 611 and the first moving valve chamber 610 constitute a first moving valve. The other opening of the pump barrel 61 is located below the discharge groove 40. The plunger 62 is slidably disposed inside the pump barrel 61. One end of the plunger 62 is connected to a drive rod 621, which is connected to an external drive device to drive the plunger 62 to perform piston movement inside the pump barrel 61. The plunger 62 has a channel 622 through it along its axis. The side of the channel 622 near the first moving valve ball 611 has a second moving valve chamber 623. The second moving valve chamber 623 is provided with a second moving valve ball 624. The second moving valve ball 624 and the second moving valve chamber 623 constitute a second moving valve.

[0065] When the drive rod 621 drives the plunger 62 to move upward within the pump cylinder 61, the first moving valve is in the open state and the second moving valve is in the closed state; when the drive rod 621 drives the plunger 62 to move downward within the pump cylinder 61, the first moving valve is in the closed state and the second moving valve is in the open state.

[0066] Since the hydraulic gradient has been quantitatively graded as described above, the power source is required to stably output adjustable water flow power. The specified reciprocating plunger pump has a positive displacement pump body structure, and its pumping flow rate has a strictly quantitative linear relationship with the plunger 62 diameter, stroke, and motion frequency. By precisely controlling the motion parameters of the plunger 62, quantitative output and fine-tuning of the flow rate can be achieved. Compared to non-positive displacement pumps such as centrifugal pumps and diaphragm pumps, this structure has no nonlinear losses due to flow leakage, and can accurately match the flow requirements corresponding to different formation hydraulic gradients. This ensures that the aforementioned target hydraulic gradient can be stably and accurately constructed and maintained. From the power source perspective, it solves the problem of "quantitative design of hydraulic gradient but inaccurate matching of power output," achieving a high degree of unity between hydraulic parameter design and power output.

[0067] Furthermore, the structure of the pump body 6 allows the first moving valve to close and the second moving valve to open when the plunger 62 moves upward, and the first moving valve to open and the second moving valve to close when the plunger 62 moves downward. This linkage logic creates a strictly unidirectional hydraulic channel in the pump body 6, ensuring that groundwater can only flow unidirectionally along the direction of "lower end of pump cylinder 61 → first moving valve → inside pump cylinder 61 → second moving valve → upper end of pump cylinder 61". Combined with the sealing structure of the first sealing component 51 and the second sealing component 52, this further strengthens the uniqueness and directionality of the artificial water circulation path, completely preventing backflow and crossflow of groundwater inside the pump body. This ensures that all the power output from the pump body is used to drive the groundwater to flow along the preset path, maximizing power utilization efficiency and ensuring that the artificial hydraulic gradient between the second well pipe 2 and the third well pipe 3 is not weakened by power loss.

[0068] Preferably, the piston 62's movement frequency f is based on the formula... Calculate; where d represents the diameter of plunger 62; s represents the stroke of plunger 62 during piston movement; K represents the formation permeability coefficient; η represents the volumetric efficiency of the pump body, with a value of 0.8 to 0.95; i represents the hydraulic gradient between the second well pipe 2 and the third well pipe 3; A represents the effective vertical water flow area, that is, the cross-sectional area of ​​the formation that actually participates in seepage when groundwater flows vertically between the second well pipe 2 and the third well pipe 3.

[0069] Based on clarifying that pump body 6 is a reciprocating plunger pump, the quantitative calculation formula for the movement frequency f of plunger 62 is further defined, and the physical meaning and value range of each parameter in the formula are clarified. This achieves a full-dimensional quantitative matching between pump body operating parameters and core indicators such as formation permeability coefficient, hydraulic gradient, and flow area. This definition is not a simple formula supplement, but rather a deep binding of the device's structural parameters, dynamic parameters, and power operation parameters, upgrading the construction of artificial hydraulic gradients from "qualitative design" to "quantitative calculation and precise control."

[0070] By defining the calculation formula for the piston 62's movement frequency f, the formation permeability coefficient K, target hydraulic gradient i, and effective vertical flow area A are linked to the pump's core operating parameters: frequency f, piston diameter d, and stroke s. During engineering design, the optimal movement frequency of piston 62 can be directly calculated from the formation parameters obtained through site surveys and the preset target hydraulic gradient, eliminating the need for experience-based selection. This design allows for precise quantitative matching between the pump's power output and the actual hydraulic demands of the formation, ensuring that the pump's output flow rate precisely supports the stable construction of the target hydraulic gradient. This avoids both insufficient power preventing the formation of an effective hydraulic gradient and excessive power leading to energy waste and flow rate runaway, thus guaranteeing the accuracy of the hydraulic drive from a computational perspective.

[0071] By using a frequency calculation formula, formation characteristic parameters, dynamic target parameters, structural parameters, and dynamic operation parameters are linked together into a complete quantitative system, forming an inseparable parameter logic closed loop. In field engineering applications, technicians only need to obtain the formation permeability coefficient K and the thickness of the contaminated aquifer (i.e., the water-passing area A) through conventional hydrogeological surveys, combine this with the hydraulic gradient i, and then, based on the preset structural parameters and volumetric efficiency η of the pump body 6, directly calculate the movement frequency of the plunger 62 without the need for complex groundwater dynamics simulations, model tests, or on-site pump testing. This design standardizes and normalizes the engineering design process of the device, significantly reducing the professional requirements for on-site technicians and avoiding parameter design deviations caused by differences in experience. At the same time, the standardized calculation method makes the construction and commissioning process of the device replicable and scalable, suitable for large-scale application in groundwater remediation projects in different regions and formations, significantly improving the device's engineering operability and market promotion value.

[0072] Preferably, the effective vertical water flow area A is determined according to the formula. Calculate; where, B represents the actual thickness of the polluted aquifer, and B represents the effective influence width of the well group, which is the range in which the second well pipe 2 and the third well pipe 3 can drive water flow in the horizontal direction, with a value of 5m to 20m.

[0073] It should be noted that the height difference Δh must not exceed the thickness of the contamination layer. To avoid cross-layer interference with the clean aquifer, the thickness of the contaminated layer is taken as equal to the height difference when calculating the effective cross-flow area of ​​the vertical water flow. .

[0074] Preferably, the second well pipe 2 and the third well pipe 3 have the same structure, which is a pipe structure. The end away from the first well pipe 1 is closed, and multiple through holes are evenly opened on the pipe wall.

[0075] The closed-end design prevents water flow short-circuiting and impurity entry, ensuring hydraulic drive efficiency and equipment stability. Uniform through-holes enable even water flow in and out, expanding the formation contact range and reducing repair blind spots. The identical structure of the two well casings simplifies processing, installation, and maintenance, improving engineering economics. Fourthly, the simple and reliable structure adapts to complex downhole environments, reducing operating and maintenance costs. It also lays the foundation for subsequent through-hole density optimization and enhances compatibility with artificial water circulation systems. It should be noted that in actual use, both the second well casing 2 and the third well casing 3 are wrapped with filter screens.

[0076] Preferably, the density of through holes gradually increases from the side closest to the first well pipe 1 to the side furthest from the first well pipe 1.

[0077] The proximal end of the well casing, connected to the first well casing 1, naturally possesses an advantage in water flow potential energy due to its proximity to the main water flow channel—the interior of the first well casing. If the perforation density is uniform, a problem arises where the water flow is concentrated near the proximal end and weak at the distal end: groundwater in the proximal strata flows in / out rapidly, while the water flow in the distal strata is difficult to drive, resulting in a repair blind zone at the distal end of the well casing. By employing a gradient design of "low density near the proximal end and high density at the distal end," the difference in the number of perforations offsets the potential energy difference—more perforations at the distal end provide a more sufficient channel for water flow, reducing the resistance to water flow in and out at the distal end. This allows groundwater to flow evenly into the second well casing 2 or evenly out of the third well casing 3 from the perforations along the entire length of the well casing, completely solving the problem of uneven distribution of "excessive water flow near the proximal end and insufficient water flow at the distal end," and achieving full-coverage water exchange in the strata surrounding the well casing.

[0078] A method for administering chemicals for groundwater remediation, using the chemical administration device proposed in this embodiment, includes the following steps: Step 1: Drilling and casing installation Based on the site hydrogeological survey results, the drilling location, the depth of the contaminated aquifer and the formation permeability coefficient were determined. The drilling formed a vertical shaft, and the first well pipe 1 was vertically lowered into the shaft, so that the outer wall of the first well pipe 1 was tightly attached to and fixed to the inner wall of the shaft.

[0079] Based on the formation permeability coefficient, the height difference Δh between the second well casing 2 and the third well casing 3 is determined. A downhole steerer is used to perform side-drilling and window opening at the lower part of the contaminated aquifer at the corresponding depth of the second well casing 2, completing the secondary drilling operation and forming a transverse borehole. Multiple second well casings 2 are evenly lowered into the transverse borehole along the circumference of the first well casing 1, so that one end of the second well casing 2 is connected to the interior of the first well casing 1, and the other end is sealed and extends to the lower part of the contaminated aquifer. Using the same side-drilling and window opening process, secondary drilling is performed at the upper part of the contaminated aquifer at the corresponding depth of the third well casing 3. Multiple third well casings 3 are evenly lowered into the transverse borehole along the circumference of the first well casing 1, so that one end of the third well casing 3 is connected to the interior of the first well casing 1, and the other end is sealed and extends to the upper part of the contaminated aquifer.

[0080] Step 2: Assembly and Deployment of Processing Units The pump barrel 61 of the pump body 6 is fixedly connected to the inner wall of the open end of the sleeve 4, and the plunger 62 is slidably set inside the pump barrel 61, so that the drive rod 621 extends upward; according to the formation parameters and the target hydraulic gradient, the reciprocating motion frequency f of the plunger 62 is determined by the frequency calculation formula, so as to match the external drive device.

[0081] The dosing nozzle 7 is fixed above the pump body 6 inside the sleeve 4, and the dosing nozzle 7 is connected to the external dosing device through a dosing pipe.

[0082] The assembled sleeve 4 is vertically lowered into the first well pipe 1, so that the open end of the sleeve 4 is located between the second well pipe 2 and the third well pipe 3, and the outlet groove 40 is located above the third well pipe 3; the first sealing component 51 and the second sealing component 52 are lowered and fixed at the gap between the sleeve 4 and the first well pipe 1 at the open end of the sleeve 4 and above the outlet groove 40, respectively, to complete the gap sealing; the drive rod 621 is connected to the external drive device to complete the overall assembly of the device.

[0083] Step 3: Device Operation and Reagent Dosing The external drive device is activated, and the plunger 62 is driven to move up and down in the pump barrel 61 according to the preset reciprocating motion frequency f. The pump body 6 starts to run. Under the action of negative pressure, the groundwater in the lower part of the contaminated aquifer enters the second well pipe 2 through the through hole of the second well pipe 2, and then flows into the interior of the first well pipe 1. It enters the pump barrel 61 through the opening end of the sleeve 4. At the same time, the external chemical supply device is activated, and the repair agent is continuously injected into the groundwater inside the sleeve 4 through the dosing nozzle 7. The groundwater flows upward under the drive of the pump body 6 and mixes thoroughly with the repair agent in the sleeve 4. The groundwater mixed with the repair agent is pushed by the plunger 62 and discharged into the annular gap between the first well pipe 1 and the sleeve 4 through the discharge groove 40 of the sleeve 4. It then flows downward to the position of the third well pipe 3 and is reinjected into the upper stratum of the contaminated aquifer through the through hole of the third well pipe 3.

[0084] Step 4: Formation and Continuous Restoration of Artificial Hydraulic Gradients As pump 6 continues to operate, groundwater is continuously extracted from the second well pipe 2, mixed with chemicals, and then continuously reinjected from the third well pipe 3, forming a stable artificial hydraulic gradient consistent with the preset value in the contaminated aquifer between the second well pipe 2 and the third well pipe 3. Driven by the hydraulic gradient, the reinjected mixed chemical groundwater flows vertically from the upper part to the lower part of the contaminated aquifer, fully contacting and reacting with the pollutants in the stratum, thereby degrading the pollutants. During the continuous remediation process, the reciprocating frequency f of the plunger 62 can be adjusted in real time through an external drive device according to the actual permeability characteristics of the strata and the on-site remediation effect. This dynamically adjusts the hydraulic gradient i and the groundwater flow velocity v. If the diffusion range of the reagent is insufficient, the frequency f is appropriately increased to increase the hydraulic gradient i and accelerate the water flow velocity. If the reagent and pollutants do not react sufficiently, the frequency f is appropriately decreased to reduce the hydraulic gradient i and slow down the water flow velocity, always maintaining the optimal remediation efficiency. The device is continuously operated until the groundwater pollutant concentration reaches the discharge standard.

[0085] Application examples The groundwater remediation of a low-flowability silty soil stratum with a permeability coefficient K=10 was performed using the reagent delivery device proposed in the embodiment. -5 cm / s = 8.64 × 10 -3 m / d, thickness of polluted aquifer Based on the graded design requirements for low-permeability strata, the target hydraulic gradient is determined to be i = 0.25, and the height difference is... The value of 4m < 5m ≤ 6m meets the requirements for the height difference of low-permeability formations.

[0086] I. Device Parameter Design: Well casing parameters: Four well casings are set for the second well casing 2 and four for the third well casing 3, which are evenly distributed around the first well casing 1. The effective influence width of the well group is B=10m. The density of through holes in the pipe walls of the second well casing 2 and the third well casing 3 gradually increases from the near end to the far end, and the density of through holes at the far end is twice that at the near end.

[0087] Pump parameters: plunger diameter d = 0.1m, stroke s = 0.2m, pump volumetric efficiency η = 0.9; effective vertical water flow area A = H P ×B=5×10=50m 2 According to the frequency calculation formula, the operating frequency of plunger 62 is f = (4 × 8.64 × 10⁻⁶) / ( ... -3 (×50×0.25) / (0.9×3.14×0.1) 2 (×0.2)≈6.03 times / s, take f=6 times / s.

[0088] Other parameters: The outlet groove 40 of the sleeve 4 is opened 0.5m above the third well pipe 3; the first sealing element 51 and the second sealing element 52 adopt rubber sealing rings to achieve gap sealing.

[0089] II. Equipment Assembly and Operation According to the delivery method of the embodiment, drilling, well casing installation and treatment unit assembly are completed; the external drive device is started, the movement frequency of plunger 62 is adjusted to 6 times / s, pump body 6 starts to run, groundwater in the lower part of the contaminated aquifer is pumped through the second well casing 2 to the first well casing 1, and then enters the sleeve 4; the external chemical supply device is started, persulfate remediation agent is delivered into the sleeve 4 through the dosing nozzle 7, and after being fully mixed with the groundwater, it is discharged through the discharge trough 40, and then reinjected into the upper part of the contaminated aquifer through the third well casing 3.

[0090] III. Verification of Hydraulic Gradient and Repair Effect After the device is operational, a stable hydraulic gradient i = 0.25 is formed between the second well pipe 2 and the third well pipe 3, perfectly matching the preset target value; according to Darcy's law, the groundwater flow velocity v = K × i = 8.64 × 10⁻⁶. -3 ×0.25=2.16×10 -3 The flow rate is m / d, which is within the optimal seepage range.

[0091] Driven by the hydraulic gradient, the agent diffuses evenly from the upper part to the lower part of the contaminated aquifer without siltation or short-circuiting, and reacts fully with the pollutants. After three months of continuous operation, the concentration of organic pollutants in the formation decreased from the initial 120 mg / L to below 0.5 mg / L, meeting the groundwater discharge standard. No cross-layer pollution or formation instability occurred, and the remediation effect was significant.

[0092] Experimental Example To verify the scientific validity and rationality of the height difference Δh between the second well casing 2 and the third well casing 3, which is determined according to the formation permeability coefficient K, and to verify the accuracy and optimization effect of the quantitative calculation of the plunger 62 movement frequency f according to the hydraulic gradient i, the following experiment was conducted.

[0093] The experiment used a vertical seepage column device made of plexiglass, with a height of 1.2m and an inner diameter of 150mm. The inside was equipped with a simulated well pipe, a plunger pump, a plugging structure, and a head monitoring device. The experimental samples were high-permeability graded sand, medium-permeability fine sand, and low-permeability silty clay. A fluorescent tracer was used to simulate the remediation agent. The experimental data were recorded using a flow sensor, a flow velocity monitor, and an image acquisition device.

[0094] Among them, for the high-permeability sample: K=1.5×10 -2 Permeability sample at cm / s: K = 4.0 × 10 -3 Low permeability sample (cm / s): K = 6.0 × 10⁻⁶ -5 cm / s; The simulated height difference Δh is set using a scaled-down equivalent to keep the hydraulic gradient consistent with the on-site engineering.

[0095] Specific experimental steps: 1) Fill the seepage column with three types of formation samples respectively, compact them in layers, and lay out simulated second and third well pipes, setting the height difference Δh according to the scale ratio.

[0096] 2) Install the sleeve, plunger pump, sealing components and monitoring equipment, and check the seal and water flow path.

[0097] 3) Set the simulated height difference according to the grading rules, calculate the plunger frequency according to the formula, and start the pump.

[0098] 4) After the seepage stabilizes, continue running for 60 minutes and record the hydraulic gradient, seepage velocity, tracer uniformity, and flow stability.

[0099] 5) Each experiment was repeated 3 times, the average value was taken, and a control group was set up for comparison.

[0100] 6) Experimental data and results, of which the simulation results of the height difference Δh graded values ​​are shown in Table 1, and the control effect of the plunger frequency f calculated according to the hydraulic gradient i is shown in Table 2.

[0101] Table 1: Simulation Experiment Results of Differentiated Values ​​of Height Difference Δh

[0102] Table 2: Control effect of plunger frequency f calculated according to hydraulic gradient i

[0103] in conclusion: According to this invention, the height difference Δh is determined by classifying the formation permeability coefficient K. A stable and suitable hydraulic gradient can be constructed in different permeable formations. The tracer diffusion uniformity is higher than 90%, and the relative blind zone rate is lower than 8%, which proves that the Δh classification value is scientific and reasonable and can effectively avoid reagent accumulation or short circuit.

[0104] According to the present invention, the plunger motion frequency f is calculated based on the hydraulic gradient i, which can make the deviation between the measured value and the theoretical value of the hydraulic gradient less than 2%, the flow stability higher than 97%, and the energy consumption reduced by 10% to 15%, proving that the frequency calculation method is accurate and reliable and can achieve precise control.

[0105] The results of the indoor simulation experiment are consistent with the engineering laws, fully verifying that the technical solution of the present invention has good applicability, stability and repair effect in various strata.

[0106] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A groundwater remediation agent dispensing device, characterized in that, include: The well casing unit includes: a first well casing, which is installed inside a vertical shaft; a plurality of second well casings, which are wound around the first well casing along the pipe axis of the first well casing, with one end of the second well casing connected to the first well casing; and a plurality of third well casings, which are wound around the first well casing along the pipe axis of the first well casing, with the third well casings located above the second well casings, and one end of the third well casings connected to the first well casing. The processing unit includes: a sleeve, which is a cylindrical structure closed at one end and open at the other, with its opening facing downwards and vertically installed inside the first well pipe. The opening of the sleeve is located between the second and third well pipes. A discharge groove is formed on the side wall of the sleeve, and the discharge groove is located above the third well pipe; a sealing component, including: a first sealing component, fixed between the sleeve and the first well pipe, located at the opening of the sleeve; a second sealing component, fixed between the sleeve and the first well pipe, located above the discharge groove; and a pump body, installed inside the sleeve, located below the discharge groove. During operation, the system is designed to allow groundwater to enter the first well pipe from the second well pipe, then enter the sleeve through the sleeve opening, and finally be discharged through the outlet channel. The groundwater then enters the third well pipe from the first well pipe and is discharged through the third well pipe. The height difference Δh between the second and third well pipes is determined according to the permeability coefficient of the contaminated aquifer, and 1m≤Δh≤6m. The dosing nozzle is fixed inside the sleeve, located above the pump body, and connected to the external dosing device. It is used to inject remediation agents into the sleeve. The remediation agents are mixed with the groundwater inside the sleeve before the groundwater is discharged through the outlet channel.

2. The groundwater remediation agent dosing device as described in claim 1, characterized in that, The specific value of the height difference Δh between the second and third well casings is: When the stratum permeability coefficient K>10 -2 When the speed is cm / s, 1m≤Δh≤2m; When the stratum permeability coefficient is 10 -4 cm / s≤K≤10 -2 When the speed is cm / s, 2m < Δh ≤ 4m; When the formation permeability coefficient K < 10 -4 When the speed is cm / s, 4m < Δh ≤ 6m.

3. The groundwater remediation agent dosing device as described in claim 2, characterized in that, The hydraulic gradient i between the second and third well casings is determined by classifying values ​​according to formation permeability characteristics, specifically as follows: When the stratum permeability coefficient K>10 -2 When the speed is cm / s, 0.05 ≤ i ≤ 0.1; When the stratum permeability coefficient is 10 -4 cm / s≤K≤10 -2 When the speed is cm / s, 0.1 < i ≤ 0.2; When the formation permeability coefficient K < 10 -4 When the speed is cm / s, 0.2 < i ≤ 0.

3.

4. The groundwater remediation agent dosing device as described in claim 3, characterized in that, The pump body includes: The pump barrel is a cylindrical structure with openings at both ends. The pump barrel and the sleeve are coaxially distributed and located inside the sleeve. The outer side wall of one opening of the pump barrel is fixed to the inner side wall of the opening of the sleeve. The opening of the pump barrel has a first moving valve chamber, and a first moving valve ball is provided in the first moving valve chamber. The first moving valve ball and the first moving valve chamber constitute a first moving valve. The other opening of the pump barrel is located below the discharge slot. A plunger is slidably disposed inside the pump barrel. One end of the plunger is connected to a drive rod, which is connected to an external drive device to drive the plunger to make piston movement inside the pump barrel. The plunger has a channel through it along its axis. The side of the channel near the first moving valve ball has a second moving valve chamber. The second moving valve chamber is provided with a second moving valve ball. The second moving valve ball and the second moving valve chamber constitute the second moving valve. When the drive rod moves the plunger upward inside the pump barrel, the first moving valve is in the open state and the second moving valve is in the closed state; when the drive rod moves the plunger downward inside the pump barrel, the first moving valve is in the closed state and the second moving valve is in the open state.

5. The groundwater remediation agent dosing device as described in claim 4, characterized in that, The piston movement frequency f is according to the formula Calculate; where d represents the diameter of the plunger; s represents the stroke of the plunger during piston movement; K represents the formation permeability coefficient; η represents the volumetric efficiency of the pump body, with a value of 0.8 to 0.95; i represents the hydraulic gradient between the second and third well pipes; A represents the effective vertical water flow area, that is, the cross-sectional area of ​​the formation that actually participates in seepage when groundwater flows vertically between the second and third well pipes.

6. The groundwater remediation agent dosing device as described in claim 5, characterized in that, The effective water flow area A of the vertical water flow is based on the formula... Calculate; where, B represents the actual thickness of the contaminated aquifer, and B represents the effective influence width of the well group, which is the range in which the second and third well pipes can drive water flow in the horizontal direction, with a value of 5m to 20m.

7. The groundwater remediation agent dosing device as described in claim 1, characterized in that, The second well pipe has the same structure as the third well pipe, which is a pipe body structure. The end away from the first well pipe is closed, and multiple through holes are evenly opened on the pipe wall.

8. The groundwater remediation agent dosing device as described in claim 7, characterized in that, The density of the through holes gradually increases from the side closer to the first well pipe to the side farther away from the first well pipe.

9. A method for administering chemicals for groundwater remediation, characterized in that, The method of administering a drug using the drug dispensing device according to any one of claims 1 to 8 includes the following steps: Drilling creates a vertical shaft, and the first well casing is lowered in; Window openings were made at the corresponding depths of the second and third well casings, and secondary drilling was carried out. The second and third well casings were then run in. Insert the sleeve containing the pump body and the dosing nozzle into the first well casing, and then insert the first sealing component and the second sealing component in sequence. Connect the dosing nozzle to the external dosing device. When the pump is started, the groundwater in the formation of the second well pipe enters the first well pipe from the second well pipe and then enters the sleeve through the sleeve opening. The dosing nozzle injects the remediation agent, which mixes with the groundwater and is discharged through the outlet trough. Then, it enters the third well pipe from the first well pipe and is discharged into the formation of the third well pipe. During this process, a stable hydraulic gradient is formed between the second and third well pipes, which drives the flow of the groundwater mixed with the remediation agent.

Images