Permeable reactive barrier simulation device
By designing a permeability reaction wall simulation device including a planar two-dimensional sand trough, steel frame, constant head water supply system and image shooting system, the limitations and experiments of PRB technology in response to large-area pollution in the prior art are solved. The device cannot effectively simulate the problem of the pollution feather capture effect of the decompressed bus PRB, and realizes an effective evaluation of the pollution feather capture effect of the decompressed bus PRB.
Patent Information
- Application Number
- CN202420783456.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-16
- Publication Date
- 2025-02-11
- Estimated Expiration
- 2034-04-16
AI Technical Summary
The existing permeability reaction wall (PRB) technology has problems such as large excavation project volume, low filler utilization rate, serious damage to the stratigraphic structure and limited application scope when dealing with large-scale pollution, and the existing experimental equipment cannot be effective. Simulate and evaluate the contaminated feather capture effect of decompressed bus PRB.
A permeable reaction wall simulation device is designed, including a planar two-dimensional sand trough, steel frame, constant head water supply system and image shooting system, to simulate and evaluate the pollution feather capture effect of a decompressed bus-type permeable reaction wall. .
This device can dynamically observe and capture the migration process of contaminated feathers in porous media, effectively evaluate the pollution feather capture effect of decompression bus PRB, and solve the problem that traditional sand tank experiments cannot reflect the decompression bus process.
Smart Images
Figure CN222461280U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of groundwater in-situ repair, in particular to a permeable reaction wall simulation device. Background Art
[0002] Permeable reactive barrier (PRB) technology is a groundwater in-situ remediation technology commonly used for the remediation of contaminated groundwater in landfills. It has the advantages of no need for external power devices and ground treatment systems, and long operating life. Typical PRB technologies include continuous PRB, funnel-gate PRB and injection PRB.
[0003] However, when dealing with large-scale pollution plumes, these PRB technologies have limitations such as large excavation workload, low filler utilization, severe damage to the stratum structure, and limited application scope. In order to overcome the technical bottlenecks of typical PRB technologies, the decompression converging PRB was proposed (Zheng Kaixuan et al., CN113896273B). However, the effectiveness of this technology has not been verified at the experimental level. At the same time, the existing experimental devices cannot effectively simulate and evaluate the capture effect of the decompression converging PRB on the pollution plume, and explore its decompression converging mechanism. Utility Model Content
[0004] In order to overcome the deficiencies of the prior art, the utility model aims to provide a permeable reaction wall simulation device.
[0005] To achieve the above purpose, the utility model provides the following solutions:
[0006] A permeable reaction wall simulation device, comprising: a plane two-dimensional sand tank, a steel frame, a constant head water supply and outlet system and an image shooting system;
[0007] The planar two-dimensional sand trough is horizontally arranged on the steel frame; a pressure-reducing converging permeable reaction wall is arranged in the planar two-dimensional sand trough; a liquid inlet and a liquid outlet are respectively arranged on both sides of the planar two-dimensional sand trough; the constant head water supply and outlet system is respectively connected to the liquid inlet and the liquid outlet, and the image shooting system is arranged in the steel frame; the image shooting system dynamically observes and captures the migration process of the pollution plume in the porous medium from the bottom of the planar two-dimensional sand trough to evaluate the pollution plume capture effect of the passive convergence-permeable reaction barrier.
[0008] Preferably, the two-dimensional plane sand trough is a rectangular trough made of highly light-transmitting organic glass, and the length, width and height of the two-dimensional plane sand trough are 800 mm, 400 mm and 30 mm respectively.
[0009] Preferably, the height of the steel frame is 800 mm.
[0010] Preferably, the shooting interval of the image shooting system is 1 minute.
[0011] Preferably, a liquid inlet chamber and a liquid outlet chamber are respectively provided on the two sides of the planar two-dimensional sand trough; a plurality of water distribution holes are evenly arranged on the partition between the liquid inlet chamber, the liquid outlet chamber and the main body of the planar two-dimensional sand trough in the width direction of the planar two-dimensional sand trough; the liquid inlet chamber is divided into two clean water injection areas and a tracer injection area between the two clean water injection areas, and the areas are separated by a water barrier; the tracer injection area is provided with two liquid inlets for evenly injecting brilliant blue solution to simulate a linear pollution source; each clean water injection area has one liquid inlet; and the liquid outlet chamber is provided with two liquid outlets.
[0012] Preferably, the constant head water supply and outlet system comprises a water supply subsystem and a water outlet subsystem;
[0013] The liquid inlet is connected to the water head constant device of the water supply subsystem; the liquid outlet is connected to the water head constant device of the water outlet subsystem.
[0014] Preferably, the liquid inlets of the clean water injection area and the tracer injection area are respectively connected to two constant water head devices with the same water head.
[0015] Preferably, the planar two-dimensional sand trough is provided with a plurality of pressure measuring holes in the longitudinal and transverse directions along the center of the pressure reducing confluence well of the pressure reducing confluence type permeable reaction wall, so as to observe the water head at each pressure measuring hole when the device is running stably.
[0016] According to the specific embodiments provided by the utility model, the utility model discloses the following technical effects:
[0017] The utility model provides a permeable reaction wall simulation device, including: a two-dimensional plane sand trough, a steel frame, a constant head water supply and outlet system and an image shooting system; the two-dimensional plane sand trough is horizontally arranged on the steel frame; a decompression confluence type permeable reaction wall is arranged in the two-dimensional plane sand trough; a liquid inlet and a liquid outlet are arranged on both sides of the two-dimensional plane sand trough respectively; the constant head water supply and outlet system is connected to the liquid inlet and the liquid outlet respectively, and the image shooting system is arranged in the steel frame; the image shooting system dynamically observes and captures the migration process of the pollution plume in the porous medium from the bottom of the two-dimensional plane sand trough to evaluate the pollution plume capture effect of the decompression confluence type permeable reaction barrier. The utility model can solve the problem that the traditional sand trough experiment cannot effectively reflect the decompression confluence process and evaluate the pollution plume capture effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0019] Figure 1 A three-dimensional schematic diagram of a permeable reaction wall simulation device provided by an embodiment of the utility model;
[0020] Figure 2 A schematic diagram of the layout of two-dimensional sand tank pressure measuring holes provided in an embodiment of the utility model.
[0021] Description of reference numerals:
[0022] 1- plane two-dimensional sand trough, 2- pressure-reducing converging permeable reaction wall, 3- steel frame, 4- constant head water supply and outlet system, 5- peristaltic pump, 6- clean water, 7- image capture system, 8- wastewater tank, 9- brilliant blue tracer, 10- partition. DETAILED DESCRIPTION
[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0024] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.
[0025] Figure 1 A three-dimensional schematic diagram of a permeable reaction wall simulation device provided by an embodiment of the utility model, as shown in Figure 1 As shown, the utility model provides an experimental device consisting of a two-dimensional sand trough 1, a constant head water supply and outlet system 4 and an image capture system 7. The two-dimensional sand trough 1 is a rectangular trough made of highly transparent organic glass, and the length, width and height of the main part are 800mm, 400mm and 30mm respectively. The schematic diagram of the device is shown in Figure 1 As shown. A decompression converging permeable reaction wall 2 is set in the plane two-dimensional sand tank 1. During the experiment, the sand tank is placed horizontally on a stainless steel frame 3 with a height of 800 mm. The camera is located directly below the center of the sand tank to dynamically observe and capture the migration process of the pollution plume in the porous medium from the bottom of the sand tank and evaluate the pollution plume capture effect of the PC-PRB. The camera shooting interval is set to 1 minute.
[0026] The two sides of the two-dimensional sand tank 1 are provided with a liquid inlet chamber and a liquid outlet chamber with a width of 30 mm. Holes with a diameter of 2 mm are evenly arranged on the partition between the liquid inlet and outlet chambers and the sand tank body to achieve the effect of uniform water distribution. The liquid inlet chamber is divided into two areas, each of which is separated by a partition 10; the middle part with a width of 200 mm is the tracer injection area, which has two injection ports for evenly injecting 30 mg·L through a peristaltic pump 5 -1 Brilliant blue solution (containing brilliant blue tracer 9) is used to simulate a linear pollution source; the 100mm wide parts on both sides are clean water injection areas, each with an injection end. The liquid outlet chamber has two outflow ends, and the waste liquid flows into the wastewater tank 8. The experiment adopts a constant head water supply method. The ports of the liquid inlet area and the liquid outlet area are respectively connected to the constant head devices. The head values are recorded as H1 and H2, respectively, and the head difference on both sides can be adjusted according to the experimental settings. Among them, the clean water injection area and the tracer injection area of the liquid inlet area are respectively connected to two constant head devices with the same head, so that the clean water 6 and the brilliant blue tracer 9 are injected into the sand trough at the same pressure. By adjusting the height difference between the two water supply tanks, the hydraulic gradient required for the simulation system can be adjusted.
[0027] Ten and six pressure measuring holes are set in the longitudinal and transverse directions along the center of the pressure reducing confluence well, respectively. Figure 2 The pressure reduction and confluence mechanism of the pressure reducing and confluence PRB was explored. The quartz sand was filled manually by wet method. The water flow rate was kept low when the sand was spread. A rubber hammer was used to tamp the quartz sand every time it was filled with a thickness of about 10 mm. Before each experiment, the sand tank was continuously flushed with clean water for 24 hours to ensure that the sand tank was in a stable saturated state.
[0028] The permeable reaction wall simulation device of this utility model can compare the capture effect of PC-PRB and C-PRB on the same pollution plume. It only needs to replace the pressure-reducing converging PRB device with a continuous PRB device (the same PRB size), while keeping other experimental conditions unchanged (hydraulic gradient is 0.020, medium particle size is 40-60 mesh). After the two systems are stable, the water head data of each corresponding observation point is recorded, and the water head distribution characteristics of the two are analyzed and compared, thereby demonstrating the effectiveness of PC-PRB technology from the experimental level and revealing the pressure-reducing converging mechanism of the pressure-reducing converging PRB. Dynamically capture the dynamic experimental images of the C-PRB simulation system and the PC-PRB simulation system at different shooting times. The results show that under the same PRB size and linear pollution source conditions, the C-PRB cannot capture all the pollution plumes, resulting in a large number of pollution plumes bypassing from both sides of the PRB; while the PC-PRB can completely intercept the pollution plume and avoid the bypass and diffusion of the pollution plume. Quantitative analysis shows that the maximum width of the upstream pollution plume of PC-PRB is 22.4 cm, the width of the pollution plume around is 0 cm, and the capture width is 22.4 cm, which proves that PC-PRB can effectively capture all pollution plumes; while the maximum width of the upstream pollution plume of C-PRB is 22.7 cm, the width of the pollution plume around is 9.4 cm, and the capture width is only 13.3 cm, indicating that C-PRB can only intercept part of the pollution plume, and the rest flows around from both sides of PRB. It is necessary to increase the length of PRB to achieve the goal of completely capturing the pollution plume. The capture width of the pollution plume of PC-PRB is 68.4% larger than that of C-PRB, which reflects a stronger pollution plume interception ability. In order to explore the reasons for the difference in pollution plume capture ability between PC-PRB and C-PRB, the pressure hole data of the two types of PRBs were used to compare and analyze their head distribution characteristics. The results show that the water head of the decompression confluence well in the PC-PRB is 0.23 cm lower than the water head at the same position in the C-PRB, that is, the depth of the decompression confluence well is 0.23 cm. Since the water head in the decompression confluence well is lower than the surrounding groundwater level, the surrounding contaminated groundwater is driven by the water head difference to flow into the well, thereby significantly improving the pollution plume capture capacity of the PC-PRB.
[0029] Furthermore, the effects of the reduced pressure confluence characteristic parameters (length of the guide tube), medium particle size, hydraulic gradient and other factors on the PC-PRB pollution plume convergence effect were investigated.
[0030] In order to explore the effect of the length of the diversion tube on the pollution plume capture capacity of PC-PRB, three groups of PC-PRB sand trough experiments with different diversion tube lengths (10 cm, 15 cm and 20 cm, respectively) were set up. Other experimental conditions remained unchanged (hydraulic gradient was 0.020, medium particle size was 40-60 mesh). The experimental images of the sand trough experiments under three groups of different diversion tube lengths were dynamically captured. The results showed that under the same PRB size and linear pollution source conditions, with the increase of the diversion tube length, the pollution plume flow width of the PC-PRB gradually decreased, while the pollution plume capture width of the PC-PRB increased from 18.6 cm to 22.4 cm. This shows that the increase in the length of the diversion tube is conducive to improving the pollution plume capture capacity of the PC-PRB. In order to investigate the effect of the diversion tube length on the depth of the decompression confluence well, the depth of the decompression confluence well in the three groups of experiments was measured by the pressure measuring hole P6. The results show that under the condition of fixed hydraulic gradient, the depth of the decompression confluence well increases with the increase of the diversion tube length. This is because the longer the diversion pipe is, the higher the initial water head at the location of the decompression confluence well is. However, due to the connectivity of the diversion pipe, the water head of the decompression confluence well drops to the same level as the buffer water layer. The depth of the decompression confluence well determines the water head difference between it and the surrounding groundwater, which in turn affects the decompression confluence effect. Therefore, the pollution plume capture width of the PC-PRB is significantly positively correlated with the length of the diversion pipe.
[0031] In order to explore the effect of hydraulic gradient on the capture capacity of PC-PRB pollution plume, four sets of PC-PRB sand trough experiments with different hydraulic gradients (0.010, 0.015, 0.020 and 0.025) were set up, and other experimental conditions remained unchanged (medium particle size was 40-60 mesh, and the length of the diversion tube was 20 cm). The experimental images of the sand trough experiments under four sets of different hydraulic gradient conditions were dynamically captured. The results showed that under the premise of a certain medium particle size and diversion tube length, the maximum width of the pollution plume formed by the same linear pollution source upstream of the PRB gradually increased with the increase of hydraulic gradient. When the hydraulic gradient increased from 0.010 to 0.025, the maximum width of the pollution plume upstream of the PRB increased from 21.1 cm to 25.5 cm. This phenomenon can be explained by the solute diffusion theory: under the same medium conditions, the increase of hydraulic gradient means that the actual groundwater flow rate increases, and the lateral diffusion effect of the solute is also enhanced, which leads to an increase in the width of the pollution plume. When the hydraulic gradient is 0.020, the maximum width of the pollution plume upstream of the PRB is 22.4 cm, and there is no pollution plume bypass phenomenon. The pollution plume capture width of the PC-PRB is equal to the maximum pollution plume width upstream of the PRB. When the hydraulic gradient is 0.025, the pollution plume bypass phenomenon occurs because the PC-PRB cannot completely capture all the pollution plumes, and the pollution plume bypass width is 0.8 cm. This is because the increase in hydraulic gradient will increase the actual groundwater flow rate, and the convective diffusion and mechanical diffusion capacity of solutes in the medium will increase accordingly, thereby weakening the interception effect of the PC-PRB on the pollution plume. The drawdown of the decompression confluence well in the four groups of experiments was measured through the pressure measuring hole P6. The results show that the drawdown of the decompression confluence well increases with the increase of the hydraulic gradient. Combined with the influence of hydraulic gradient changes on the capture width of the PC-PRB pollution plume, it can be inferred that the pollution plume capture capacity of the PC-PRB not only depends on the drawdown of the decompression confluence well, but may be related to the ratio of the drawdown and hydraulic gradient.
[0032] In order to explore the effect of medium particle size on the capture capacity of PC-PRB pollution plume, three groups of PC-PRB sand trough experiments with different medium particle sizes (40-60 mesh, 20-40 mesh and 10-20 mesh) were set up. Other experimental conditions remained unchanged (hydraulic gradient was 0.010, and the length of the diversion tube was 20 cm). The experimental images of the sand trough experiments under three groups of different medium particle size conditions were dynamically captured. The results showed that under the premise of constant hydraulic gradient and diversion tube length, the maximum width of the pollution plume upstream of PRB increased from 21.1 cm to 27.4 cm with the increase of medium particle size. This phenomenon can be explained by the following two reasons: First, due to its poor sorting, quartz sand with larger particle size has greater differences in the size and shape of the accumulated pores, thus having a stronger mechanical dispersion ability, that is, a greater dispersion; second, due to its higher permeability, quartz sand with larger particle size has a faster water flow velocity under the same hydraulic gradient conditions, which also enhances the convective diffusion effect of the solute. When the medium particle size was 20-40 mesh and 10-20 mesh, the PC-PRB experienced pollutant circumferential migration, and the width of the pollutant plume circumferential flow increased with the increase of the medium particle size. In addition, with the increase of the medium particle size, the pollution plume capture width of the PC-PRB decreased, which may be related to the increase of the hydrodynamic diffusion coefficient caused by the increase of the medium particle size. The depth of the pressure reduction confluence well in the three groups of experiments was measured by the pressure measuring hole P6. The results showed that the depth of the pressure reduction confluence well did not change significantly in the three groups of experiments, which was only 0.01cm. This shows that the depth of the pressure reduction confluence well has no significant relationship with the medium particle size.
[0033] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0034] This article uses specific examples to illustrate the principle and implementation of the utility model. The above examples are only used to help understand the method and core idea of the utility model. At the same time, for those skilled in the art, according to the idea of the utility model, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be understood as limiting the utility model.
Claims
1. A permeable reaction wall simulation device, characterized in that: include: Planar two-dimensional sand trough, steel frame, constant head water supply and outlet system and image capture system; The planar two-dimensional sand trough is horizontally arranged on the steel frame; a decompression converging permeable reaction wall is arranged in the planar two-dimensional sand trough; a liquid inlet and a liquid outlet are respectively arranged on both sides of the planar two-dimensional sand trough; the constant head water supply and outlet system is respectively connected to the liquid inlet and the liquid outlet, and the image shooting system is arranged in the steel frame; the image shooting system dynamically observes and captures the migration process of the pollution plume in the porous medium from the bottom of the planar two-dimensional sand trough, so as to evaluate the pollution plume capture effect of the decompression converging permeable reaction barrier.
2. The permeable reactive wall simulation device according to claim 1, characterized in that: The two-dimensional plane sand trough is a rectangular trough made of highly light-transmitting organic glass, and the length, width and height of the two-dimensional plane sand trough are 800 mm, 400 mm and 30 mm respectively.
3. The permeable reactive wall simulation device according to claim 1, characterized in that: The height of the steel frame is 800 mm.
4. The permeable reactive wall simulation device according to claim 1, characterized in that: The shooting interval of the image shooting system is 1 minute.
5. The permeable reactive wall simulation device according to claim 1, characterized in that: A liquid inlet chamber and a liquid outlet chamber are respectively arranged on the two sides of the planar two-dimensional sand trough; a plurality of water distribution holes are evenly arranged on the partition between the liquid inlet chamber, the liquid outlet chamber and the main body of the planar two-dimensional sand trough in the width direction of the planar two-dimensional sand trough; the liquid inlet chamber is divided into two clean water injection areas and a tracer injection area between the two clean water injection areas, and each area is separated by a water-blocking plate; the tracer injection area is provided with two liquid inlets for evenly injecting brilliant blue solution to simulate a linear pollution source; each clean water injection area has one liquid inlet; and the liquid outlet chamber is provided with two liquid outlets.
6. The permeable reactive wall simulation device according to claim 5, characterized in that: The constant head water supply and outlet system comprises a water supply subsystem and a water outlet subsystem; The liquid inlet is connected to the water head constant device of the water supply subsystem; the liquid outlet is connected to the water head constant device of the water outlet subsystem.
7. The permeable reactive wall simulation device according to claim 6, characterized in that: The liquid inlets of the clean water injection area and the tracer injection area are respectively connected to two constant water head devices with the same water head.
8. The permeable reactive wall simulation device according to claim 1, characterized in that: The planar two-dimensional sand trough is provided with a plurality of pressure measuring holes in the longitudinal and transverse directions along the center of the pressure reducing confluence well of the pressure reducing confluence type permeable reaction wall, so as to observe the water head at each pressure measuring hole when the device is in stable operation.