Soil carbon sequestration-reinforcement cooperative system based on CO2 mineralization

Abstract

The invention discloses a soil carbon sequestration-reinforcement cooperative system based on CO2 mineralization. The soil carbon sequestration-reinforcement cooperative system comprises a carbon alkali liquor preparation device, a mineralization liquid injection device and a sampling monitoring device. The carbon alkali liquor preparation device comprises a CO2 gas cylinder, the CO2 gas cylinder is connected with a reaction device, and the reaction device is connected with a mineralized liquid injection device through a multi-stage filtering assembly; the mineralization liquid injection device comprises an air compressor, the air compressor is connected with an air pressure control box, the air pressure control box is connected with a carbon alkali liquid storage tank and a calcium source liquid storage tank in parallel through a CO2 filter, the carbon alkali liquid storage tank is connected with a multi-stage filtering assembly, and the carbon alkali liquid storage tank and the calcium source liquid storage tank are jointly connected with the rotary spraying drilling machine; the sampling monitoring device comprises a monitoring well and a resistivity and CO2 monitoring instrument, and the monitoring well and a sampling area are arranged according to the jet grouting injection hole site. According to the method, mineralization or carbon sequestration of the soil body can be achieved through CO2 in the depth-controllable soil body according to the type and the requirement of the soil body, or in-situ reinforcement of the soil body is achieved, or the carbon sequestration-reinforcement synergistic effect of the soil body is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental engineering geology, and in particular relates to a soil carbon fixation-reinforcement synergistic system based on CO2 mineralization. Background Art

[0002] The fundamental path to reduce emissions and increase carbon sinks includes zero-carbon, low-carbon, decarbonization, carbon compensation and other technologies. Among them, the decarbonization CO2 mineralization technology has attracted much attention due to its advantages of low cost, large scale, low environmental risk and good long-term stability. This technology imitates the process of natural minerals weathering and absorbing CO2 in nature, and uses minerals or other substances containing calcium and magnesium ions to react with CO2 to generate stable solid carbonates (such as CaCO3 / MgCO3) to achieve CO2 storage.

[0003] On the other hand, some special soils such as soft soil, fill soil, and contaminated soil whose original strength and structure cannot meet the engineering requirements need to be reinforced, but traditional soil reinforcement methods often rely on a large amount of cement, lime and other materials. The production process of these materials not only consumes a lot of energy, but also produces a large amount of CO2 emissions, which is not in line with the development trend of green and low-carbon geotechnical engineering. In contrast, the use of CO2 mineralization technology for soil reinforcement can not only reduce the use of traditional building materials such as cement, but also achieve the effective utilization and fixation of CO2.

[0004] Therefore, based on the demand for special soil reinforcement, it is urgent to develop a system that can convert CO2 into mineralized liquid that can be injected into the soil to achieve soil carbon fixation, in-situ reinforcement of special soils, and synergistic effects of soil carbon fixation and reinforcement. Summary of the invention

[0005] The purpose of the present invention is to provide a soil carbon fixation-reinforcement synergistic system based on CO2 mineralization, which can mineralize or achieve soil carbon fixation through CO2 in soil with controllable depth, or achieve in-situ reinforcement of the soil, or achieve soil carbon fixation-reinforcement synergistic effect according to the soil type and needs.

[0006] To achieve the above-mentioned object, the present invention provides a soil carbon fixation-reinforcement synergistic system based on CO2 mineralization, comprising a carbon alkali solution preparation device, a mineralization solution injection device and a sampling and monitoring device;

[0007] The carbon alkali solution preparation device includes a CO2 gas cylinder, a multi-stage filtering component and a reaction device, the CO2 gas cylinder is connected to the reaction device through a gas valve, the reaction device is connected to an agitator and a pressure gauge, and the reaction device is connected to a mineralizing liquid injection device through a multi-stage filtering component;

[0008] The mineralized liquid injection device includes a carbon alkali liquid storage tank, a calcium source liquid storage tank, an air compressor, an air pressure control box, a CO2 filter and a rotary jet drilling rig, the air compressor is connected to the air pressure control box, the air pressure control box is connected in parallel to the carbon alkali liquid storage tank and the calcium source liquid storage tank through the CO2 filter, the carbon alkali liquid storage tank is connected to a multi-stage filtration component, and the carbon alkali liquid storage tank and the calcium source liquid storage tank are connected to the rotary jet drilling rig together;

[0009] The sampling and monitoring device includes monitoring wells, resistivity and CO2 monitoring instruments. The monitoring wells are arranged according to the rotary jet injection hole positions, and a sampling area is provided around each rotary jet injection hole position.

[0010] As a further solution of the present invention: the multi-stage filtration device comprises a primary vacuum filter and a secondary vacuum filter, the primary vacuum filter and the secondary vacuum filter are both divided into an upper part and a lower part, a replaceable filter membrane is placed between the upper part and the lower part, and the upper part and the lower part are fixed by a detachable fixing frame;

[0011] The first-stage vacuum filter and the second-stage vacuum filter are connected to vacuum pump one and vacuum pump two through valve one and valve two respectively;

[0012] The upper inlet end of the first-stage vacuum filter is connected to the liquid outlet of the reaction device, the liquid outlet of the reaction device is provided with a control valve 1, the lower outlet end of the first-stage vacuum filter is connected to the upper inlet end of the second-stage vacuum filter, the lower outlet end of the first-stage vacuum filter is provided with a control valve 2, the lower outlet end of the second-stage vacuum filter is connected to the carbon alkali liquid storage tank, and the lower outlet end of the second-stage vacuum filter is provided with a control valve 3.

[0013] As a further solution of the present invention: the pore size of the replaceable filter membrane of the first-stage vacuum filter is larger than the pore size of the replaceable filter membrane of the second-stage vacuum filter.

[0014] As a further solution of the present invention: the connecting ends of the carbon alkali liquid storage tank, the calcium source liquid storage tank and the CO2 filter are respectively provided with an air valve 1 and an air valve 2, and the connecting ends of the carbon alkali liquid storage tank, the calcium source liquid storage tank and the rotary jet drilling rig are respectively provided with a liquid outlet valve 1 and a liquid outlet valve 2.

[0015] As a further solution of the present invention: the rotary jet injection holes are distributed in a triangular hole arrangement, and the monitoring well is located at the center of the triangular distribution.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The present invention converts CO2 into a mineralized liquid that can be injected into and reinforce the soil. Compared with the traditional soil reinforcement method, the present invention highly integrates soil carbon fixation with in-situ soil reinforcement, implements the mineralization of exogenous CO2 in the soil with controllable depth, and then realizes the synergistic effect of soil carbon fixation and reinforcement. It can also realize soil carbon fixation or soil reinforcement tracking according to the soil type and demand. This system realizes the resource utilization of CO2 fixation in the soil or CO2 reinforcement of the soil through the chemical phase transformation of CO2, reduces the processing cost of CO2, and helps to realize the effective geological storage of CO2 to achieve the carbon storage goal.

[0018] 2) The multi-stage filtration component uses replaceable filter membranes with different pore sizes for graded filtration to effectively remove impurities produced by the reaction, ensuring the purity and stability of the carbon alkali solution. The replaceable filter membranes are convenient for replacement, cleaning and maintenance.

[0019] 3) The system is highly flexible and adaptable, and can adjust the ratio, injection speed and injection volume of carbon alkali solution and calcium source solution according to the actual situation and needs of the soil to ensure the best carbon fixation or reinforcement effect.

[0020] 4) The setting of sampling and monitoring devices enables the carbon fixation or reinforcement parameters before and after treatment to be monitored and evaluated. This not only helps to accurately evaluate the carbon fixation or reinforcement effect, but also optimizes the plan and provides a scientific basis for subsequent similar projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an overall schematic diagram of the soil carbon fixation-reinforcement synergistic system based on CO2 mineralization of the present invention.

[0022] Figure 2 For the present invention Figure 1 Schematic diagram of the replaceable filter membrane and removable fixing clip at A in the middle.

[0023] Figure 3 This is a schematic diagram of the locations of the rotary jet injection holes, monitoring wells and sampling areas proposed in the present invention.

[0024] In the figure: 1. CO2 gas cylinder, 2. gas valve, 3. agitator, 4. pressure gauge, 5. reaction device, 6. control valve one, 7. support frame, 8. primary vacuum filter, 9. control valve two, 10. control valve three, 11. secondary vacuum filter, 12. vacuum pump two, 13. valve two, 14. vacuum pump one, 15. valve one, 16. carbon alkali liquid storage tank, 17. gas valve one, 18. CO2 filter, 19. air pressure control box, 20. air compressor, 21. liquid outlet valve one, 22. gas valve two, 23. calcium source liquid storage tank, 24. liquid outlet valve two, 25. rotary jet drilling rig, 26. rotary jet injection hole, 27. resistivity and CO2 monitoring instrument, 28. monitoring well, 29. sampling area, 30. topsoil, 31. soil to be treated, 32. replaceable filter membrane, 33. detachable fixing frame. DETAILED DESCRIPTION

[0025] The present invention will be further described below by way of examples.

[0026] like Figure 1 and Figure 3 As shown, a soil carbon fixation-reinforcement synergistic system based on CO2 mineralization includes a carbon alkali solution preparation device, a mineralization solution injection device and a sampling monitoring device; according to the soil type and demand, CO2 is used to mineralize in the soil with controllable depth to either achieve soil carbon fixation, or to achieve in-situ reinforcement of the soil, or to achieve soil carbon fixation-reinforcement synergistic effect;

[0027] The mineralization solution is composed of a carbonate solution and a calcium source solution. The carbonate solution is obtained by filtering a metaaluminate solution having a concentration lower than 1 mol / L and reacting with CO2. The calcium source solution is a calcium salt that can react with the carbonate solution to generate a precipitate, including but not limited to calcium chloride, and its concentration is consistent with that of the carbonate solution.

[0028] The carbon alkali solution preparation device includes a CO2 gas cylinder 1, a multi-stage filtering component and a reaction device 5, the CO2 gas cylinder 1 is connected to the reaction device 5 through a gas valve 2, the reaction device 5 is connected with a stirrer 3 and a pressure gauge 4, and the reaction device 5 is connected to a mineralized liquid injection device through a multi-stage filtering component; the multi-stage filtering component and the reaction device 5 are fixed by a support frame 7, the gas valve 2 is used to control the air intake, cooperate with the stirrer 3 to make the aluminate solution and CO2 fully react in the reaction device 5, and then filter through the multi-stage filtering component to maintain the fluidity of the solution;

[0029] The mineralized liquid injection device includes a carbon alkali liquid storage tank 16, a calcium source liquid storage tank 23, an air compressor 20, an air pressure control box 19, a CO2 filter 18 and a rotary jet drilling machine 25, wherein the air compressor 20 is connected to the air pressure control box 19, the air pressure control box 19 is connected in parallel to the carbon alkali liquid storage tank 16 and the calcium source liquid storage tank 23 through the CO2 filter 18, the carbon alkali liquid storage tank 16 is connected to a multi-stage filtering component, and the carbon alkali liquid storage tank 16 and the calcium source liquid storage tank 23 are connected to the rotary jet drilling machine 25; wherein the CO2 filter 18 is filled with a solution capable of absorbing CO2, including but not limited to a sodium hydroxide solution;

[0030] The sampling monitoring device includes a monitoring well 28 and a resistivity and CO2 monitoring instrument 27 . The monitoring well 28 is arranged according to the rotary jet injection hole positions 26 . A sampling area 29 is provided around each rotary jet injection hole position 26 .

[0031] In order to ensure the filtering effect of the multi-stage filtering device, further, such as Figure 1 and Figure 2 As shown, the multi-stage filtering device includes a primary vacuum filter 8 and a secondary vacuum filter 11, the primary vacuum filter 8 and the secondary vacuum filter 11 are both divided into an upper part and a lower part, a replaceable filter membrane 32 is placed between the upper part and the lower part, and the upper part and the lower part are fixed by a detachable fixing frame 33;

[0032] The first-stage vacuum filter 8 and the second-stage vacuum filter 11 are connected to the vacuum pump 1 14 and the vacuum pump 2 12 through the valve 1 15 and the valve 2 13 respectively;

[0033] The upper inlet end of the first-stage vacuum filter 8 is connected to the liquid outlet of the reaction device 5, and the liquid outlet of the reaction device 5 is provided with a control valve 1 6. The lower outlet end of the first-stage vacuum filter 8 is connected to the upper inlet end of the second-stage vacuum filter 11, and the lower outlet end of the first-stage vacuum filter 8 is provided with a control valve 2 9. The lower outlet end of the second-stage vacuum filter 11 is connected to the carbon alkali liquid storage tank 16, and the lower outlet end of the second-stage vacuum filter 11 is provided with a control valve 3 10.

[0034] Further, the pore size of the replaceable filter membrane 32 of the primary vacuum filter 8 is larger than the pore size of the replaceable filter membrane 32 of the secondary vacuum filter 11. The pore size of the replaceable filter membrane 32 of the primary vacuum filter 8 may be 1 μm, and the pore size of the replaceable filter membrane 32 of the secondary vacuum filter 11 may be between 0.2 μm and 0.45 μm, ensuring effective removal of the oxyalumina particles produced by the reaction and maintaining the fluidity of the solution.

[0035] Furthermore, the connecting ends of the carbon alkali liquid storage tank 16, the calcium source liquid storage tank 23 and the CO2 filter 18 are respectively provided with an air valve 17 and an air valve 22, and the connecting ends of the carbon alkali liquid storage tank 16, the calcium source liquid storage tank 23 and the rotary jet drilling rig 25 are respectively provided with a liquid outlet valve 1 21 and a liquid outlet valve 2 24.

[0036] Further, such as Figure 3 As shown, the rotary jet injection holes 26 are distributed in a triangular pattern, the distance between adjacent rotary jet injection holes 26 is 2-2.5 m, the monitoring well 28 is located at the center of the triangular distribution, and the sampling area 29 is 1-1.5 m away from the rotary jet injection holes.

[0037] When the present invention is specifically used:

[0038] 1. Place the aluminate solution into the reaction device 5 and seal it, close the liquid outlet control valve 6 of the reaction device 5, open the gas valve 2 and introduce the CO2 in the CO2 cylinder 1 into the reaction device 5, so that the ratio of the aluminate to the CO2 substance is 2:1;

[0039] 2. When the predetermined amount of CO2 is reached in the reaction device 5, close the gas valve 2 and turn on the stirrer 3 to allow the aluminate solution to fully react with CO2. The reaction is terminated when the pressure gauge 4 shows a stable reading and no more precipitation is generated;

[0040] 3. Open the liquid outlet control valve 6 of the reaction device 5, close the liquid outlet control valve 9 of the primary vacuum filter 8, open the vacuum pump 14 and valve 15, and allow the suspension after the reaction to enter the primary vacuum filter 8 for primary filtration. The primary vacuum filter 8 can select a replaceable filter membrane 32 with a pore size of 1 μm;

[0041] 4. After the primary filtration is completed, close the vacuum pump 14, valve 15 and control valve 3 10, open the control valve 2 9, open the vacuum pump 2 12 and valve 2 13, and allow the primary filtered solution to enter the secondary vacuum filter 11 for secondary filtration. The secondary vacuum filter 11 can select a replaceable filter membrane 32 with a pore size between 0.2 μm and 0.45 μm;

[0042] 5. After the secondary filtration is completed, close the vacuum pump 2 12 and the valve 2 13, open the control valve 3 10, put the carbon alkali solution obtained after the two-stage filtration into the carbon alkali solution storage tank 16, and prepare the calcium source solution and put it into the calcium source solution storage tank 23;

[0043] 6. Level the site and arrange the jet injection holes 26 in a triangular pattern, with the spacing between adjacent jet injection holes 26 being 2-2.5 m. Arrange a monitoring well 28 at the center of the triangular distribution, and arrange a sampling area 29 at a distance of 1-1.5 m from the jet injection holes 26;

[0044] 7. Open the air inlet valve 17 of the carbon alkali liquid storage tank 16 and the liquid outlet valve 21 of the carbon alkali liquid storage tank 16, start the air compressor 20 and filter out the CO2 in the air through the CO2 filter 18, control the injection speed through the air pressure control box 19, drill with the rotary jet drilling rig 25, inject the carbon alkali liquid and stir, the drilling speed of the rotary jet drilling rig 25 is 0.5-1m / min, the rotation speed is 10-15r / min, and the injection speed of the carbon alkali liquid is 20-50L / min;

[0045] 8. After drilling to the set depth, close the air inlet valve 17 of the carbon alkali liquid storage tank 16 and the outlet valve 21 of the carbon alkali liquid storage tank 16, open the air inlet valve 22 of the calcium source liquid storage tank 23 and the outlet valve 24 of the calcium source liquid storage tank 23, inject the calcium source liquid, lift the drill pipe and stir in the reverse direction, the lifting speed of the rotary jet drilling rig 25 is 0.5-1m / min, the reverse rotation speed is 10-15r / min, the injection speed of the calcium source liquid is 20-50L / min, and the volume of the carbon alkali liquid and the calcium source liquid injected into the soil is 1-1.5 times the pore volume of the soil;

[0046] 9. After the drill pipe is lifted, close the air inlet valve 22 of the calcium source liquid storage tank 23 and the outlet valve 24 of the calcium source liquid storage tank 23;

[0047] 10. Move the drilling rig to the next rotary jet injection hole 26, and repeat steps 7-9 until the soil at all rotary jet injection holes 26 and their surroundings are effectively treated;

[0048] 11. Conduct conductivity testing of the treated area using resistivity and CO2 monitoring instruments 27 12h, 24h, 36h, 48h, and 72h after the injection is completed, and compare the test data with that before the treatment to analyze the diffusion and migration of the CO2 mineralized liquid;

[0049] 12. During and after the injection process, the CO2 leakage in the site is monitored by resistivity and CO2 monitoring instruments 27;

[0050] 13. If it is necessary to monitor the soil carbon fixation process separately, take samples from the sampling area 29 12h, 24h, 36h, 48h, and 72h after the injection is completed, take control samples from the non-injected area, and measure carbon fixation parameters such as the insoluble calcium carbonate content and CO2 release to verify the carbon fixation effect;

[0051] 14. If it is necessary to monitor the soil reinforcement process separately, take samples from the sampling area 29 12h, 24h, 36h, 48h, and 72h after the injection is completed, take control samples from the non-injected area, and measure the reinforcement parameters such as pH, unconfined compressive strength, cohesion, internal friction angle, and compression coefficient to verify the reinforcement effect;

[0052] 15. If it is necessary to monitor the soil carbon fixation-reinforcement synergistic process, samples are taken from the sampling area 29 12h, 24h, 36h, 48h, and 72h after the injection is completed, and control samples are taken from the non-injected area. The carbon fixation parameters and reinforcement parameters are then measured to verify the carbon fixation-reinforcement synergistic effect.

Claims

1. A soil carbon fixation-reinforcement synergistic system based on CO2 mineralization, characterized in that: It includes a carbon alkali solution preparation device, a mineralizing solution injection device and a sampling and monitoring device; The carbon alkali solution preparation device comprises a CO2 gas cylinder (1), a multi-stage filtering component and a reaction device (5), wherein the CO2 gas cylinder (1) is connected to the reaction device (5) via a gas valve (2), the reaction device (5) is connected to an agitator (3) and a pressure gauge (4), and the reaction device (5) is connected to a mineralizing solution injection device via the multi-stage filtering component; The mineralized liquid injection device comprises a carbon alkali liquid storage tank (16), a calcium source liquid storage tank (23), an air compressor (20), an air pressure control box (19), a CO2 filter (18) and a rotary jet drilling machine (25), wherein the air compressor (20) is connected to the air pressure control box (19), the air pressure control box (19) is connected in parallel to the carbon alkali liquid storage tank (16) and the calcium source liquid storage tank (23) through the CO2 filter (18), the carbon alkali liquid storage tank (16) is connected to a multi-stage filtering component, and the carbon alkali liquid storage tank (16) and the calcium source liquid storage tank (23) are connected to the rotary jet drilling machine (25); The sampling monitoring device comprises a monitoring well (28) and a resistivity and CO2 monitoring instrument (27). The monitoring well (28) is arranged according to the rotary jet injection hole positions (26), and a sampling area (29) is arranged around each rotary jet injection hole position (26).

2. The soil carbon fixation-reinforcement synergistic system based on CO2 mineralization according to claim 1 is characterized in that: The multi-stage filtering device comprises a primary vacuum filter (8) and a secondary vacuum filter (11), wherein the primary vacuum filter (8) and the secondary vacuum filter (11) are both divided into an upper part and a lower part, a replaceable filter membrane (32) is placed between the upper part and the lower part, and the upper part and the lower part are fixed by a detachable fixing frame (33); The first-stage vacuum filter (8) and the second-stage vacuum filter (11) are connected to vacuum pump one (14) and vacuum pump two (12) respectively through valve one (15) and valve two (13); The upper inlet end of the primary vacuum filter (8) is connected to the liquid outlet of the reaction device (5), the liquid outlet of the reaction device (5) is provided with a control valve 1 (6), the lower outlet end of the primary vacuum filter (8) is connected to the upper inlet end of the secondary vacuum filter (11), the lower outlet end of the primary vacuum filter (8) is provided with a control valve 2 (9), the lower outlet end of the secondary vacuum filter (11) is connected to the carbon alkali liquid storage tank (16), and the lower outlet end of the secondary vacuum filter (11) is provided with a control valve 3 (10).

3. The soil carbon fixation-reinforcement synergistic system based on CO2 mineralization according to claim 2 is characterized in that: The pore size of the replaceable filter membrane (32) of the primary vacuum filter (8) is larger than the pore size of the replaceable filter membrane (32) of the secondary vacuum filter (11).

4. The soil carbon fixation-reinforcement synergistic system based on CO2 mineralization according to claim 2 is characterized in that: The connecting ends of the carbon alkali liquid storage tank (16), the calcium source liquid storage tank (23) and the CO2 filter (18) are respectively provided with a first air valve (17) and a second air valve (22); the connecting ends of the carbon alkali liquid storage tank (16), the calcium source liquid storage tank (23) and the rotary jet drilling machine (25) are respectively provided with a first liquid outlet valve (21) and a second liquid outlet valve (24).

5. A soil carbon fixation-reinforcement synergistic system based on CO2 mineralization according to any one of claims 1 to 4, characterized in that: The rotary jet injection holes (26) are distributed in a triangular hole arrangement, and the monitoring well (28) is located at the center of the triangular distribution.

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