Circulating well device for in-situ remediation of polluted soil and underground water containing LNAPL

Abstract

The invention relates to a circulating well device for in-situ remediation of LNAPL-containing polluted soil and underground water. The circulating well device comprises a chemical injection device, a water suction pump, a water treatment device, an upper-section packer, a lower-section packer, a first chemical injection pipe, a second chemical injection pipe and a water suction pipe, wherein the upper-section packer, the lower-section packer, the first chemical injection pipe, the second chemical injection pipe and the water suction pipe are mounted in a circulating well shaft; the upper-section packer and the lower-section packer are simultaneously set, so that the circulating well shaft can be packed into an upper-section shaft, a middle-section shaft and a lower-section shaft; the upper-section shaft, the middle-section shaft and the lower-section shaft are all provided with screen pipes, and the screen pipe corresponding to the middle-section shaft is located below the underground water level. The first medicine injection pipe is connected with a medicine injection device and is communicated with the upper-section shaft; the second medicine injection pipe is connected with a medicine injection device and is communicated with the lower-section shaft; the water pumping pipe is connected with a water pump and extends below the screen pipe corresponding to the middle-section shaft; a spraying pipe is arranged at the tail end of the first medicine injection pipe, and the water suction pump is connected with a water treatment device. According to the method, the contaminated soil, the underground water and the LNAPL can be efficiently remedied at the same time, and the remediation cost is further reduced.

Description

Technical Field

[0001] This invention relates to a circulating well device for in-situ remediation of contaminated soil and groundwater containing LNAPL. Background Technology

[0002] Petroleum is a mixture mainly composed of various hydrocarbons, cycloalkanes, aromatic hydrocarbons, resins, asphaltenes, and small amounts of non-hydrocarbon compounds. It is one of the world's three major energy sources and is often referred to as the "lifeblood of industry." With the development of the petroleum industry and the continuous increase in energy consumption, the area of ​​oil extraction has been expanding. However, leaks and spills during extraction, refining, and transportation have led to soil and groundwater pollution.

[0003] Because crude oil is poorly soluble in water and has a lower density than water, it tends to float above the groundwater surface after entering an aquifer, forming light non-aqueous phase liquids (LNAPLs). Simultaneously, under varying water conditions during wet and dry seasons, LNAPL smears will form in the soil medium of the vadose zone, resulting in contaminated soil, LNAPLs, and contaminated groundwater from top to bottom. Summary of the Invention

[0004] To achieve simultaneous remediation of contaminated soil, LNAPL, and contaminated groundwater, this invention proposes a circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater. The technical solution proposed in this invention is as follows:

[0005] In a first aspect, the present invention provides a circulating well device for in-situ remediation of contaminated soil and groundwater containing LNAPL, comprising: a chemical injection device, a water pump, a water treatment device, and an upper packer, a lower packer, a first chemical injection pipe, a second chemical injection pipe, and a water pumping pipe installed in the circulating well shaft.

[0006] The simultaneous setting of the upper packer and the lower packer can divide the circulating wellbore into an upper wellbore, a middle wellbore, and a lower wellbore.

[0007] The upper section, the middle section, and the lower section of the well are all equipped with screen pipes, and the screen pipe corresponding to the middle section of the well is below the groundwater level.

[0008] The first injection tube is connected to the injection device and also connects to the upper section of the wellbore;

[0009] The second injection pipe is connected to the injection device and also connects to the lower section of the wellbore;

[0010] The pumping pipe is connected to the pumping pump and extends to below the screen pipe corresponding to the middle section of the well shaft;

[0011] The first injection tube is equipped with a spray pipe at its end, and the spray pipe has multiple spray holes.

[0012] The water pump is connected to a water treatment device.

[0013] In one or more embodiments, an air injection device is also included;

[0014] The air injection device includes a first air injection pipe, a second air injection pipe, a third air injection pipe, an air compressor, a first air injection control valve, a second air injection control valve, a third air injection control valve, a first exhaust control valve, and a second exhaust control valve.

[0015] The air compressor is connected to the first air injection pipe, the second air injection pipe and the third air injection pipe respectively;

[0016] The first air injection control valve is located between the first air injection pipe and the air compressor; the second air injection control valve and the first exhaust control valve are located between the second air injection pipe and the air compressor; and the third air injection control valve and the second exhaust control valve are located between the third air injection pipe and the air compressor.

[0017] The first gas injection pipe passes through the upper packer and the lower packer and communicates with the lower section of the wellbore. An aeration head is provided at the end of the first gas injection pipe.

[0018] Both the upper packer and the lower packer include a rubber sleeve;

[0019] The second gas injection tube passes through the upper packer and connects to the rubber sleeve of the lower packer;

[0020] The third gas injection pipe is connected to the rubber sleeve of the upper packer.

[0021] In one or more embodiments, the drug injection device includes a drug tank, a drug injection pump, a drug injection pump control valve, a first drug injection control valve, and a second drug injection control valve;

[0022] One end of the injection pump is connected to the medicine tank, and the other end of the injection pump is connected to the first injection tube and the second injection tube respectively;

[0023] The injection pump control valve is located between the injection pump and the medicine tank, the first injection control valve is located between the first injection pipe and the injection pump, and the second injection control valve is located between the second injection pipe and the injection pump.

[0024] In one or more embodiments, a screen is provided inside the screen tube.

[0025] In one or more embodiments, the diameter of the upper section of the wellbore is greater than the diameter of the middle section of the wellbore and the diameter of the lower section of the wellbore.

[0026] In one or more embodiments, the upper packer further includes a central tube disposed within the rubber sleeve;

[0027] The first air injection pipe, the second air injection pipe, the third air injection pipe, the second medicine injection pipe, and the water pumping pipe are evenly arranged along the central pipe.

[0028] In one or more embodiments, a hanging rod is also included;

[0029] The top of the circulating well shaft is provided with a well cover, and the upper packer is suspended from the well cover by the hanging rod.

[0030] In one or more embodiments, a short section and a plurality of quick connectors are also included;

[0031] The upper packer is connected to the hanging rod via the quick connector;

[0032] The upper packer and the lower packer are respectively connected to the two ends of the short section via the quick connector.

[0033] In one or more embodiments, a sand-sinking pipe disposed at the bottom of the lower section of the wellbore is also included.

[0034] In one or more embodiments, a water quality monitor is also included, which is connected to the pumping pipe.

[0035] Secondly, the present invention provides an in-situ remediation method for contaminated soil and groundwater containing LNAPL, comprising:

[0036] Control the upper packer and the lower packer to set simultaneously, thus dividing the circulation wellbore into an upper section, a middle section, and a lower section.

[0037] The pre-prepared leaching agent is injected into the upper section and the lower section of the well using an injection device, and the contaminated groundwater in the middle section of the well is pumped out by a water pump and pumped into a water treatment device.

[0038] The leaching agent flowing out from the upper section of the well shaft seeps downwards to leach pollutants in the soil medium and flows back into the screen tube of the middle section of the well shaft, forming a positive circulation; while the leaching agent flowing out from the lower section of the well shaft flows upwards to remediate the groundwater, clean the LNAPL residues on the aquifer medium, and flows back into the screen tube of the middle section of the well shaft, forming a reverse circulation.

[0039] After the water pump has been running for the first preset time, the water pump will be turned off.

[0040] After the injection device has been running for a second preset time, the water pump is turned on so that the polluted groundwater continuously flows back from the screen pipe in the middle section of the well and is pumped to the surface through the pumping pipe, where it enters the water treatment device for treatment.

[0041] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0042] The circulating well device for in-situ remediation of LNAPL-contaminated soil and groundwater provided by this invention forms three sections—upper, middle, and lower—within the circulating well casing through an upper and lower packer. A prepared leaching agent is injected into the upper and lower sections of the circulating well casing using an injection device. Contaminated groundwater in the middle section is pumped out using a pump. The leaching agent flowing out of the upper section seeps downwards due to gravity and the pressure difference created by extraction, and flows back into the screen tube of the middle section. By injecting the leaching agent into the screen tube of the upper section and extracting it in the screen tube of the middle section, a positive circulation is formed, leaching the contaminants in the soil medium to achieve the purpose of remediating the contaminated soil. The leaching agent in the lower section of the well flows horizontally out of the screen pipe and then flows upwards to the screen pipe in the middle section of the well. By injecting leaching agent and air into the lower section, the natural degradation process of the contaminated groundwater is accelerated. Simultaneously, extraction occurs at the screen pipe in the middle section, creating a vertical reverse circulation within the groundwater. This process extracts LNAPL while simultaneously washing away any LNAPL residue on the aquifer medium due to the leaching agent's action. The pump stops operating after a first preset time and restarts after a second preset time of leaching agent flow. This allows the leached contaminated groundwater to continuously flow back through the screen pipe in the middle section and be pumped to the surface via the pump pipe, thus forming an integrated leaching-extraction process. This invention integrates forward and reverse circulation within the same circulating well, enabling efficient remediation of contaminated soil, groundwater, and LNAPL simultaneously, further reducing remediation costs.

[0043] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the overall structure of the circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater provided in an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the packer structure used in the circulating well of the present invention;

[0048] Figure 3 This is a top view of the packer structure used in the circulating well of the present invention.

[0049] Explanation of the attached figure numbers:

[0050] 10-Medicine tank; 11-Injection pump control valve; 20-Injection pump; 30-First injection pipe; 31-First injection control valve; 32-Spray pipe; 40-Second injection pipe; 41-Second injection control valve; 50-First air injection pipe; 51-First air injection control valve; 60-Second air injection pipe; 61-Second air injection control valve; 62-First exhaust control valve; 70-Third air injection pipe; 71-Third air injection control valve; 72-Second exhaust control valve; 80-Air compressor; 90-Water pumping pipe; 91-Water pumping control valve; 92-Water pump; 93-Water pump control valve. 100-Water treatment device, 110-Well cover, 120-Upper packer, 121-Central pipe, 122-Quick connector, 123-Pipe assembly, 124-Roller sleeve, 130-Groundwater surface, 140-Short section, 150-Screen, 160-Lower pumping pipe, 170-Lower packer, 180-Lower section of first air injection pipe, 181-Aeration head, 190-Lower section of second chemical injection pipe, 200-Sediment settling pipe, 210-Lower screen pipe, 220-Lower wellbore, 230-Middle screen pipe, 240-Middle wellbore, 250-Upper screen pipe, 260-Upper wellbore, 270-Hanging rod. Detailed Implementation

[0051] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0052] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0053] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] The inventors discovered that leaked crude oil and oily wastewater can enter groundwater through ground fissures and tectonic fractures, leading to groundwater contamination. Because crude oil is poorly soluble in water and less dense, it tends to float above the groundwater surface after entering the aquifer, forming low-lying organic pollutants (LNAPLs). Simultaneously, variations in water levels during wet and dry seasons create LNAPL smears in the vadose zone soil, resulting in contaminated soil, LNAPLs, and contaminated groundwater from top to bottom. Current soil and groundwater remediation technologies mainly include stabilization, soil washing, chemical oxidation-reduction, thermal desorption, and bioremediation, which are further categorized as in-situ and ex-situ remediation depending on whether contaminants are transferred. However, these technologies face significant safety risks and their application is limited. Groundwater circulation well technology artificially alters the water pressure distribution within the well, creating pressure differential disturbances and vertical circulation flow. This drives contaminated groundwater from the surrounding area into the well, where volatile and semi-volatile organic compounds are stripped away – a method of in-situ remediation. Currently, groundwater circulation well technology has been widely used in the field of soil and groundwater remediation. While related patents have been published, most involve groundwater circulating within the well, resulting in a small radius of influence, long circulation cycles, and high energy consumption. Furthermore, most currently developed circulation wells are single-well, single-circulation designs, which are difficult to apply to contaminated soil, LNAPL, and contaminated groundwater, failing to meet the inventors' expectations. Therefore, the inventors, through further research and development, created this invention.

[0056] Example 1

[0057] This invention provides a circulating well device for in-situ remediation of LNAPL-contaminated soil and groundwater, referring to... Figure 1 As shown, it includes: a chemical injection device, a water pump 92, a water treatment device 100, and an upper packer 120, a lower packer 170, a first chemical injection pipe 30, a second chemical injection pipe 40, and a water pumping pipe 90 installed in the circulation well shaft.

[0058] The simultaneous setting of the upper packer 120 and the lower packer 170 can divide the circulating wellbore into three sections: upper, middle, and lower. These are referred to as the upper wellbore 260, the middle wellbore 240, and the lower wellbore 220, respectively.

[0059] The upper section wellbore 260, the middle section wellbore 240, and the lower section wellbore 220 are all equipped with screen pipes, as shown in the reference. Figure 1 As shown, in this invention, the screen pipe of the upper section wellbore 260 is referred to as the upper section screen pipe 250, the screen pipe of the middle section wellbore 240 is referred to as the middle section screen pipe 230, and the screen pipe of the lower section wellbore 220 is referred to as the lower section screen pipe 210.

[0060] The first injection pipe 30 is connected to the injection device and the upper section of the wellbore 260. A spray pipe 32 is provided at the end of the first injection pipe 30. The spray pipe 32 has multiple spray holes, and the washing agent is provided to the upper section of the wellbore 260 through the spray holes on the spray pipe 32.

[0061] The second injection pipe 40 is connected to the injection device and communicates with the lower section of the wellbore 220. Specifically, the lower section 190 of the second injection pipe, i.e. the end of the second injection pipe 40, extends into the lower section of the wellbore 220 to provide rinsing agent into the lower section of the wellbore 220.

[0062] The pumping pipe 90 is connected to the pumping pump 92 and extends to the screen pipe corresponding to the middle section well 240, i.e., the middle section screen pipe 230. The middle section screen pipe 230 is below the groundwater level 130 and is used to extract LNAPL and the polluted groundwater after rinsing.

[0063] A pumping control valve 91 is provided between the pumping pipe 90 and the pumping pump 92. The pumping control valve 91 is used to control whether LNAPL and the polluted groundwater after rinsing are pumped out from the middle section well 240.

[0064] The aforementioned pumping pipe 90 comprises two parts: an upper pumping pipe and a lower pumping pipe 160. The upper pumping pipe is connected to the pumping pump 92, and the lower pumping pipe 160 passes through the upper packer 120 and connects to the upper pumping pipe. A one-way valve (not shown in the figure) is installed at the bottom suction inlet of the lower pumping pipe 160 to control the extraction of the leached contaminated groundwater and LNAPL to the surface.

[0065] The water pump 92 is connected to the water treatment device 100, which is used to further treat the pumped contaminated groundwater. A water pump control valve 93 is installed between the water pump 92 and the water treatment device 100. The water pump control valve 93 is used to control whether the pumped, rinsed contaminated groundwater and LNAPL enter the water treatment device 100 for treatment. The structure and specific treatment method of the water treatment device 100 can be referred to the specific description in the prior art, and will not be repeated here.

[0066] This invention belongs to the field of soil and groundwater pollution remediation technology, specifically relating to a circulating well device for in-situ remediation of LNAPL-contaminated soil and groundwater. The device comprises an upper packer 120 and a lower packer 170, forming upper, middle, and lower sections within the circulating well. A prepared leaching agent is injected into the upper section 260 and lower section 220 of the circulating well using an injection device. A pump 92 draws contaminated groundwater from the middle section 240, causing the leaching agent flowing from the upper section 260 to seep downwards due to gravity and the pressure difference created by extraction, and then back into the middle screen tube 230 of the middle section 240. By injecting the leaching agent into the upper screen tube 250 of the upper section 260 and extracting it from the middle screen tube 230 of the middle section 240, a positive circulation is formed. The leaching agent leaches the pollutants in the soil medium, achieving the purpose of remediating the contaminated soil. The leachate in the lower section of the wellbore 220 flows horizontally out of the lower screen pipe 210 and then flows upwards to the middle screen pipe 230 of the middle section of the wellbore 240. Injecting leachate and air into the lower section of the wellbore 220 accelerates the natural degradation process of the contaminated groundwater. Simultaneously, extraction occurs at the middle screen pipe 230 of the middle section of the wellbore 240, creating a vertical reverse circulation within the groundwater. This extraction removes LNAPL, and the leachate also washes away any LNAPL residue remaining on the aquifer medium. The pump 92 stops operating after a first preset time. After a second preset time of leachate flow, the pump 92 restarts, allowing the leachated contaminated groundwater to continuously flow back from the middle screen pipe 230 of the middle section of the wellbore 240 and be pumped to the surface through the pump pipe 90, thus forming an integrated cyclical leachate-extraction process. This invention integrates forward and reverse circulation within the same circulation well, enabling efficient remediation of contaminated soil, groundwater, and LNAPL simultaneously, further reducing remediation costs.

[0067] Compared to traditional groundwater circulation well technology, which can only remediate contaminated groundwater, the circulation well device for in-situ remediation of contaminated soil and groundwater containing LNAPL provided by this invention can remediate both contaminated soil and light non-aqueous phase liquids (LNAPL) in addition to groundwater remediation, thus having a wider range of applications. Furthermore, traditional groundwater circulation well technology requires large equipment on the surface, occupying significant ground space. In existing production facilities, there is generally no space to place such equipment. In contrast, the device mentioned in this invention has most of its equipment fixed inside the circulation well casing, underground, occupying less surface space and reducing safety risks.

[0068] In an optional embodiment, a gas injection device is also included;

[0069] The air injection device includes a first air injection pipe 50, a second air injection pipe 60, a third air injection pipe 70, an air compressor, a first air injection control valve 51, a second air injection control valve 61, a third air injection control valve 71, a first exhaust control valve 62, and a second exhaust control valve 72.

[0070] The air compressor 80 is connected to the first air injection pipe 50, the second air injection pipe 60 and the third air injection pipe 70 respectively;

[0071] The first air injection control valve 51 is disposed between the first air injection pipe 50 and the air compressor 80, the second air injection control valve 61 and the first exhaust control valve 62 are disposed between the second air injection pipe 60 and the air compressor 80, and the third air injection control valve 71 and the second exhaust control valve 72 are disposed between the third air injection pipe 70 and the air compressor 80.

[0072] The first gas injection pipe 50 passes through the upper packer 120 and the lower packer 170 and communicates with the lower section wellbore 220. An aeration head 181 is provided at the lower section 180 of the first gas injection pipe 50 to ensure sufficient aeration. By injecting leaching agents into the lower section wellbore 220 and aerating it, the natural degradation process of polluted groundwater can be accelerated.

[0073] Both the upper packer 120 and the lower packer 170 include a rubber sleeve 124;

[0074] The second gas injection pipe 60 passes through the upper packer 120 and connects to the rubber sleeve 124 of the lower packer 170. When the second gas injection control valve 61 is opened, the gas injected by the second gas injection pipe 60 enters the internal channel of the rubber sleeve 124 of the lower packer 170, and the rubber sleeve 124 expands, causing the lower packer 170 to be seated on the wall of the circulating well.

[0075] The third gas injection pipe 70 connects to the rubber sleeve 124 of the upper packer 120. When the third gas injection control valve 71 is opened, the gas injected through the third gas injection pipe 70 enters the internal channel of the rubber sleeve 124 of the upper packer 120, causing the rubber sleeve 124 to expand and seal the upper packer 120 onto the wellbore wall. The simultaneous sealing of the upper packer 120 and the lower packer 170 can divide the wellbore into an upper wellbore 260, a middle wellbore 240, and a lower wellbore 220.

[0076] The setting method of the upper packer 120 and the lower packer 170 is as follows: Start the air compressor 80, open the second air injection control valve 61 and the third air injection control valve 71, and the second air injection pipe 60 and the third air injection pipe 70 start to inflate the rubber sleeves 124 of the upper packer 120 and the lower packer 170 respectively. During the inflation process, observe the pressure gauges (not shown in the figure) set on the second air injection pipe 60 and the third air injection pipe 70. When the setting pressure is reached, close the second air injection control valve 61 and the third air injection control valve 71, stop the inflation, and complete the setting.

[0077] The diameters of the first gas injection pipe 50, the second gas injection pipe 60, and the third gas injection pipe 70 can be set according to the needs of actual engineering applications, such as 2 to 5 mm.

[0078] In an optional embodiment, the drug injection device includes a drug tank 10, a drug injection pump 20, a drug injection pump control valve 11, a first drug injection control valve 31, and a second drug injection control valve 41;

[0079] One end of the injection pump 20 is connected to the medicine tank 10, and the other end of the injection pump 20 is connected to the first injection pipe 30 and the second injection pipe 40 respectively; refer to Figure 1 As shown, the first injection pipe 30 and the second injection pipe 40 meet at the front end and are connected to the injection pump 20 to provide flushing agent into the upper section wellbore 260 and the lower section wellbore 220.

[0080] The injection pump control valve 11 is located between the injection pump 20 and the medicine tank 10. The injection pump control valve 11 is used to control whether the rinsing agent in the medicine tank 10 enters the injection pump 20.

[0081] The first injection control valve 31 is located between the first injection pipe 30 and the injection pump 20. The first injection control valve 31 is used to control whether to inject the rinsing agent into the upper section of the wellbore 260 through the first injection pipe 30.

[0082] The second injection control valve 41 is located between the second injection pipe 40 and the injection pump 20. The second injection control valve 41 is used to control whether to inject rinsing agent into the lower section of the wellbore 220 through the second injection pipe 40.

[0083] The method for injecting leaching agents into the upper section wellbore 260 and the lower section wellbore 220 is as follows: The agent tank 10 is used for preparing the leaching agent. After preparing the leaching agent according to the remediation formula, the injection pump control valve 11 is opened, the injection pump 20 is started, and the first injection control valve 31 and the second injection control valve 41 are opened to begin injecting the leaching agent into the soil areas of the upper section wellbore 260 and the lower section wellbore 220. When the leaching agent injected in the upper section reaches the lower interface of the upper screen pipe 250, the leaching agent enters the outside of the circulation well through the upper screen pipe 250 and flows towards the middle section wellbore 240, leaching the contaminated soil outside the circulation well during the flow. The leaching agent in the lower section wellbore 220 flows horizontally out of the lower screen pipe 210 and then flows upwards to the middle screen pipe 230 of the middle section wellbore 240, accelerating the natural degradation process of the contaminated groundwater. Simultaneously, extraction is carried out at the mid-section screen pipe 230 of the mid-section wellbore 240. While extracting LNAPL, the residual LNAPL on the aquifer medium can be washed away by the washing agent.

[0084] The above-mentioned circulating well device for in-situ remediation of contaminated soil and groundwater containing LNAPL is used as follows: the upper section and the lower section of the circulating well are sealed by the upper packer 120 and the lower packer 170, so that the circulating well is divided into upper, middle and lower three-section spaces. The prepared leaching agent is injected into the upper section wellbore 260 and the lower section wellbore 220 using the injection pump 20. The contaminated groundwater in the middle section wellbore 240 is drawn out by the pump 92. The leaching agent flowing out of the upper section wellbore 260 seeps downwards due to gravity and the pressure difference caused by the extraction, and flows back into the middle section screen pipe 230, forming a positive circulation. The leaching agent in the lower section screen pipe 210 flows horizontally out of the lower section screen pipe 210 and then flows upwards back into the middle section screen pipe 230, forming a reverse circulation. The pump 92 can be stopped after running for 5-15 minutes. After the upper and lower leaching agents have flowed for 20-30 minutes, the pump 92 is turned on again, so that the contaminated groundwater after leaching continuously flows back from the middle section screen pipe 230 and is drawn to the surface through the pump pipe 90, thus forming an integrated leaching-extraction process. Since there isn't much water in the well, the water pump 92 can be started intermittently to pump water, achieving energy-saving effects.

[0085] In the above method, when the leaching agent is used to leach contaminated groundwater and soil, the pump is started. Simultaneously with the injection of the agent, the pump 92 draws contaminated groundwater from the intermediate wellbore 240, creating a negative pressure in the intermediate wellbore 240. This allows the leaching agent, after leaching the contaminated soil, to enter the intermediate wellbore 240 and be pumped to the surface through the pumping pipe 90. Alternatively, when using the leaching agent to leach contaminated groundwater and soil, the pump 92 can be left unstarted, allowing the leaching agent to thoroughly wash away the contaminants in the soil. After the leaching agent has been flowing for 20-30 minutes, the pump 92 is then turned on, causing the leached contaminated groundwater and the leaching agent, after leaching the contaminated soil, to continuously flow back from the intermediate screen tube 230 and be pumped to the surface through the pumping pipe 90.

[0086] This invention integrates forward and reverse circulation within a single circulating well, enabling simultaneous remediation of contaminated soil, groundwater, and LNAPL. By injecting a leaching agent into the lower section of the well (220) and aerating it using aeration heads (181), the natural degradation process of contaminated groundwater is accelerated. Simultaneously, extraction occurs at the middle screen tube (230), creating a vertical reverse circulation within the groundwater. This extraction of LNAPL, combined with the action of the leaching agent and the shear force of the water, washes away any LNAPL residue remaining in the aquifer. Furthermore, by injecting a leaching agent into the upper section of the well (260) and extracting it at the middle screen tube (230), a forward circulation is formed within the circulating well, leaching contaminants from the soil medium to achieve soil remediation. This invention enables highly efficient remediation of contaminated soil, groundwater, and LNAPL, further reducing remediation costs.

[0087] The parameters of the above-mentioned injection pump 20, water pump 92, and chemical tank 10 can be set according to the needs of actual engineering applications. For example, depending on the site conditions, the injection flow rate of the injection pump 20 can be 1-3 m³ / h. 3 / h, output pressure is 3~10Bar. Pump 92 has a pumping flow rate of 0.5~5m³ / h. 3 The pumping speed is 10-50 m. The viscosity of the agent in the agent tank 10 should be controlled between 0 and 4000 mPa·s.

[0088] In an optional embodiment, a screen 150 is provided inside the screen tube to prevent debris from outside the well shaft from entering the well shaft.

[0089] In an optional embodiment, the circulating well of the present invention adopts a variable-diameter well design, wherein the diameter of the upper section well 260 is larger than the diameter of the middle section well 240 and the diameter of the lower section well 220. By adopting a variable-diameter well, the influence radius of the circulating well can be increased, the remediation effect of contaminated groundwater can be improved, and the circulation cycle can be shortened while reducing remediation energy consumption. The diameters of the upper section well 260, the middle section well 240, and the lower section well 220 can be set according to the needs of actual engineering applications, such as the diameter of the upper section well 260 being 100-150 cm, and the diameters of the middle section well 240 and the lower section well 220 being 60-110 cm. The present invention forms a dual-circulation circulating well device integrating forward and reverse circulation through the variable-diameter well design and the setting of triple screen pipes. At the same time, the coupled leaching process realizes the simultaneous remediation of contaminated soil, LNAPL, and contaminated groundwater.

[0090] In an optional embodiment, the upper packer 120 further includes a central tube 121 disposed within the rubber sleeve 124; see reference Figure 2 and Figure 3 As shown, the pipe assembly 123, namely the first gas injection pipe 50, the second gas injection pipe 60, the third gas injection pipe 70, the second chemical injection pipe 40, and the water extraction pipe 90, is uniformly arranged along the central pipe 121. By uniformly arranging the first gas injection pipe 50, the second gas injection pipe 60, the third gas injection pipe 70, and the second chemical injection pipe 40 along the central pipe 121, the injected rinsing agent and gas are more evenly distributed, and the stability of the upper packer 120 is improved.

[0091] In an optional embodiment, the above-described circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater further includes a hanging rod 270;

[0092] Reference Figure 2 As shown, a well cover 110 is provided on the top of the circulating well shaft, and the upper packer 120 is suspended on the well cover 110 by the hanging rod 270 to fix the upper packer 120.

[0093] In an optional embodiment, the above-described circulating well device for in-situ remediation of contaminated soil and groundwater containing LNAPL further includes a short section 140 and a plurality of quick connectors 122;

[0094] Reference Figure 2 As shown, the upper packer 120 is connected to the hanging rod 270 through the quick connector 122, and the upper packer 120 is fixed to the well cover 110 to realize the installation of the upper packer 120.

[0095] Reference Figure 1As shown, the upper packer 120 and the lower packer 170 are respectively connected to both ends of the short section 140 via the quick connector 122. The short section 140 is disposed between the upper packer 120 and the lower packer 170. One end of the short section 140 is connected to the upper packer 120 via a quick connector 122, and the other end of the short section 140 is connected to the lower packer 170 via a quick connector 122, thereby achieving a fixed connection between the lower packer 170 and the upper packer 120, and thus installing the upper packer 120 and the lower packer 170 inside the circulating wellbore.

[0096] Reference Figure 1 As shown, the gas injected through the second gas injection pipe 60 passes through the upper packer 120, through the short section 140, and then enters the internal channel of the rubber sleeve 124 of the lower packer 170. The gas injected through the first gas injection pipe 50 passes through the upper packer 120, through the short section 140 and the lower packer 170, and enters the lower wellbore 220.

[0097] In an optional embodiment, the above-mentioned circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater further includes a sedimentation pipe 200 disposed at the bottom of the lower section of the well shaft. The sedimentation pipe 200 is used to filter out sand and gravel from the contaminated groundwater. The length of the sedimentation pipe 200 can be set according to the actual application requirements, and the length of the sedimentation pipe 200 is not less than 30cm.

[0098] In an optional embodiment, the above-mentioned circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater further includes a water quality monitor connected to the pumping pipe 90, which can perform real-time online monitoring of the contaminated groundwater. By acquiring parameters such as the concentration and composition of the contaminated groundwater, the pumped and leached groundwater is treated by the water treatment device 100.

[0099] To further understand the circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater provided by the present invention, the present invention will now be described in detail with reference to specific embodiments.

[0100] To achieve both forward and reverse circulation simultaneously within the circulating wellbore, the upper packer 120 and lower packer 170 need to be inflated first. Once the pressure reaches a certain level, the upper packer 120 and lower packer 170 will be seated against the wellbore wall, forming three spaces within the circulating wellbore: an upper space, a middle space, and a lower space. Specifically, the air compressor 80 is started, and the second injection control valve 61 and the third injection control valve 71 are opened to begin inflating the rubber sleeves 124 of the upper packer 120 and the lower packer 170, respectively. During inflation, the pressure gauges (not shown in the figure) on the second injection pipe 60 and the third injection pipe 70 are observed. Once the setting pressure is reached, the second injection control valve 61 and the third injection control valve 71 are closed, inflation is stopped, and the setting is complete.

[0101] After preparing the leaching agent according to the remediation formula, open the injection pump control valve 11, start the injection pump 20, open the first injection control valve 31 and the second injection control valve 41, and start injecting the leaching agent into the soil areas of the upper section well 260 and the lower section well 220.

[0102] When the leaching agent injected in the upper section reaches the lower interface of the upper screen tube 250, the leaching agent enters the outside of the circulation well through the upper screen tube 250 and flows towards the middle section well tube 240, leaching the contaminated soil outside the circulation well during the flow. The pumping control valve 91 and pumping control valve 93 are opened, and the pumping pump 92 is started, drawing the contaminated groundwater from the middle section well tube 240 into the water treatment device 100. At this time, the contaminated groundwater around the outside of the middle screen tube 230 continues to enter the middle section of the circulation well through the screen 150 on the inner wall of the middle screen tube 230. The contaminated groundwater around the outside of the lower screen tube 210 also flows back into the middle screen tube 230 of the circulation well. This forms a vertical positive circulation with the upper packer 120 of the circulation well as the interface, and a vertical reverse circulation with the lower packer 170 of the circulation well as the interface.

[0103] During the injection process, opening the first gas injection control valve 51 allows for aeration of the polluted groundwater in the lower section of the circulating well 220, accelerating the natural degradation process of the polluted groundwater. The first gas injection control valve 51 is equipped with a pressure valve at its front end to provide appropriate aeration pressure.

[0104] After the repair is completed, the upper packer 120 and the lower packer 170 can be unsealed by opening the first exhaust control valve 62 and the second exhaust control valve 72.

[0105] In this embodiment, the upper packer 120 and the lower packer 170 can be set and unset simultaneously, or set and unset individually, depending on the depth of the pollutants in the contaminated site. By controlling the setting and unsetting of the upper packer 120 and the lower packer 170, it is possible to activate either the forward circulation or the reverse circulation.

[0106] If the contaminated site is located between the upper section 260 and the middle section 240 of the well, only the upper packer 120 needs to be sealed, and the first injection control valve 31 can be opened to inject leaching agent into the soil area of ​​the upper section 260. When the leaching agent injected in the upper section reaches the lower interface of the upper screen tube 250, the leaching agent enters the outside of the circulation well through the upper screen tube 250 and flows towards the middle section 240, leaching the contaminated soil outside the circulation well during the flow. Afterwards, the pumping control valve 91 and the pumping control valve 93 are opened, and the pumping pump 92 is started to extract the contaminated groundwater in the middle section 240 of the circulation well into the water treatment device 100. At this time, the contaminated groundwater around the outside of the middle screen tube 230 will continue to enter the middle section of the circulation well through the screen 150 on the inner wall of the middle screen tube 230. In this way, a vertical positive circulation is formed with the upper packer 120 of the circulation well as the interface.

[0107] If the contaminants at the contaminated site are located between the middle section wellbore 240 and the lower section wellbore 220, open the injection pump control valve 11, start the injection pump 20, open the second injection control valve 41, and begin injecting the leaching agent into the soil area of ​​the lower section wellbore 220. Aeration is then performed using the aeration head 181 to accelerate the natural degradation process of the contaminated groundwater. When the injected leaching agent reaches the lower interface of the lower screen tube 210, the leaching agent enters the outside of the circulation well through the lower screen tube 210 and flows towards the middle section wellbore 240, leaching the contaminated groundwater outside the circulation well during the flow. Afterward, open the pumping control valve 91 and the pumping pump control valve 93, start the pumping pump 92, and pump the contaminated groundwater in the middle section wellbore 240 into the water treatment device 100. At this time, the contaminated groundwater around the outside of the middle section screen tube 230 will continue to enter the middle section wellbore 240 through the screen 150 on the inner wall of the middle section screen tube 230. The polluted groundwater around the outer side of the lower screen pipe 210 will also flow back into the middle screen pipe 230 of the circulation well, thus forming a vertical reverse circulation with the lower packer 170 of the circulation well as the interface.

[0108] Example 2

[0109] This invention provides an in-situ remediation method for contaminated soil and groundwater containing LNAPL, comprising:

[0110] Control the upper packer 120 and the lower packer 170 to be set simultaneously, and divide the circulation well into an upper wellbore 260, a middle wellbore 240 and a lower wellbore 220;

[0111] The pre-prepared rinsing agent is injected into the upper section wellbore 260 and the lower section wellbore 220 using the injection device, and the polluted groundwater in the middle section wellbore 240 is pumped out by the water pump 92 and pumped into the water treatment device 100.

[0112] The leaching agent flowing out from the upper section wellbore 260 seeps downwards to leach pollutants in the soil medium and flows back into the screen tube of the middle section wellbore 240, forming a positive circulation; while the leaching agent flowing out from the lower section wellbore 220 flows upwards to remediate groundwater, clean the LNAPL residues on the aquifer medium, and flows back into the screen tube of the middle section wellbore 240, forming a reverse circulation.

[0113] After the water pump 92 has been running for the first preset time, the water pump 92 is turned off.

[0114] After the injection device has been running for a second preset time, the water pump 92 is turned on so that the polluted groundwater continuously flows back from the screen pipe of the middle section well 240 and is pumped to the ground through the water pumping pipe 90 and enters the water treatment device 100 for treatment.

[0115] The specific implementation of the in-situ remediation method for LNAPL-containing contaminated soil and groundwater provided in this embodiment can be referred to the detailed description of the circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater in the above embodiment. Where the description is repeated, it will not be repeated.

[0116] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "upper," "lower," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0117] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. This invention is not limited to any single aspect, nor to any single embodiment, nor to any combination and / or substitution of these aspects and / or embodiments. Each aspect and / or embodiment of this invention can be used alone, or in combination with one or more other aspects and / or other embodiments.

[0118] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater, characterized in that, include: The equipment includes a chemical injection device, a water pump, a water treatment device, and an upper packer, a lower packer, a first chemical injection pipe, a second chemical injection pipe, and a water pumping pipe installed inside the circulating well shaft. The simultaneous setting of the upper packer and the lower packer can divide the circulating wellbore into an upper wellbore, a middle wellbore, and a lower wellbore. The upper section, the middle section, and the lower section of the well are all equipped with screen pipes, and the screen pipe corresponding to the middle section of the well is below the groundwater level. The first injection tube is connected to the injection device and also connects to the upper section of the wellbore; The second injection pipe is connected to the injection device and also connects to the lower section of the wellbore; The pumping pipe is connected to the pumping pump and extends to below the screen pipe corresponding to the middle section of the well shaft; The first injection tube is provided with a spray pipe at its end, and the spray pipe has multiple spray holes. The water pump is connected to a water treatment device.

2. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, It also includes an air injection device; The air injection device includes a first air injection pipe, a second air injection pipe, a third air injection pipe, an air compressor, a first air injection control valve, a second air injection control valve, a third air injection control valve, a first exhaust control valve, and a second exhaust control valve. The air compressor is connected to the first air injection pipe, the second air injection pipe and the third air injection pipe respectively; The first air injection control valve is located between the first air injection pipe and the air compressor; the second air injection control valve and the first exhaust control valve are located between the second air injection pipe and the air compressor; and the third air injection control valve and the second exhaust control valve are located between the third air injection pipe and the air compressor. The first gas injection pipe passes through the upper packer and the lower packer and communicates with the lower section of the wellbore. An aeration head is provided at the end of the first gas injection pipe. Both the upper packer and the lower packer include a rubber sleeve; The second gas injection tube passes through the upper packer and connects to the rubber sleeve of the lower packer; The third gas injection pipe is connected to the rubber sleeve of the upper packer.

3. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, The drug injection device includes a drug tank, a drug injection pump, a drug injection pump control valve, a first drug injection control valve, and a second drug injection control valve; One end of the injection pump is connected to the medicine tank, and the other end of the injection pump is connected to the first injection tube and the second injection tube respectively; The injection pump control valve is located between the injection pump and the medicine tank, the first injection control valve is located between the first injection pipe and the injection pump, and the second injection control valve is located between the second injection pipe and the injection pump.

4. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, A screen is installed inside the screen tube.

5. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, The diameter of the upper section of the wellbore is greater than the diameter of the middle section of the wellbore and the diameter of the lower section of the wellbore.

6. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 2, characterized in that, The upper packer also includes a central tube disposed inside the rubber cylinder; The first air injection pipe, the second air injection pipe, the third air injection pipe, the second medicine injection pipe, and the water pumping pipe are evenly arranged along the central pipe.

7. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, It also includes hanging poles; The top of the circulating well shaft is provided with a well cover, and the upper packer is suspended from the well cover by the hanging rod.

8. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 7, characterized in that, It also includes short sections and multiple quick couplings; The upper packer is connected to the hanging rod via the quick connector; The upper packer and the lower packer are respectively connected to the two ends of the short section via the quick connector.

9. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, It also includes a sand settling pipe installed at the bottom of the lower section of the wellbore.

10. The circulating well device for in-situ remediation of LNAPL-containing contaminated soil and groundwater according to claim 1, characterized in that, It also includes a water quality monitor, which is connected to the pumping pipe.

11. A method for in-situ remediation of LNAPL-contaminated soil and groundwater, characterized in that, Using the circulating well apparatus for in-situ remediation of LNAPL-containing contaminated soil and groundwater as described in any one of claims 1-10, the method comprises: Control the upper packer and the lower packer to set simultaneously, thus dividing the circulation wellbore into an upper section, a middle section, and a lower section. The pre-prepared leaching agent is injected into the upper section and the lower section of the well using an injection device, and the contaminated groundwater in the middle section of the well is pumped out by a water pump and pumped into a water treatment device. The leaching agent flowing out from the upper section of the well shaft seeps downwards to leach pollutants in the soil medium and flows back into the screen tube of the middle section of the well shaft, forming a positive circulation; while the leaching agent flowing out from the lower section of the well shaft flows upwards to remediate the groundwater, clean the LNAPL residues on the aquifer medium, and flows back into the screen tube of the middle section of the well shaft, forming a reverse circulation. After the water pump has been running for a first preset time, the water pump shall be turned off. After the injection device has been running for a second preset time, the water pump is turned on so that the polluted groundwater continuously flows back from the screen pipe in the middle section of the well and is pumped to the surface through the pumping pipe, where it enters the water treatment device for treatment.

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