A soil carbon sequestration-reinforcement synergistic system based on CO2 mineralization

Abstract

The application discloses a kind of based on CO2 mineralization's soil carbon fixation-reinforcement synergic system, including carbon alkali solution preparation device, mineralized liquid injection device and sampling monitoring device;Carbon alkali solution preparation device includes CO2 gas cylinder, CO2 gas cylinder is connected with reaction device, and reaction device is connected with mineralized liquid injection device by multistage filtration component;Mineralized liquid injection device includes air compressor, air compressor is connected with gas pressure control box, and gas pressure control box is connected with carbon alkali solution storage tank, calcium source liquid storage tank by CO2 filter in parallel, carbon alkali solution storage tank is connected with multistage filtration component, and carbon alkali solution storage tank and calcium source liquid storage tank are connected with rotary jet drilling machine jointly;Sampling monitoring device includes monitoring well, resistivity and CO2 monitoring instrument, and monitoring well and sampling area are arranged according to rotary jet injection hole site.The application can be mineralized in depth controllable soil body by CO2 according to soil body type and demand or realize soil body carbon fixation, or realize in-situ reinforcement of soil body, or realize soil body carbon fixation-reinforcement synergic effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental engineering geology, and particularly relates to a soil carbon fixation-reinforcement synergistic system based on CO2 mineralization. BACKGROUND

[0002] The fundamental path of emission reduction and carbon sink is zero carbon, low carbon, decarbonization, carbon compensation and other technologies. The CO2 mineralization technology of decarbonization is concerned due to its low cost, large scale, small environmental risk and long-term stability. The technology simulates the process of natural mineral weathering and CO2 absorption in nature, uses minerals containing calcium and magnesium ions or other substances to react with CO2 to generate stable solid carbonates (such as CaCO3 / MgCO3), and realizes the sequestration of CO2.

[0003] On the other hand, some special soils such as soft soil, fill soil and contaminated soil with original strength and structure that cannot meet engineering requirements need to be reinforced, but the traditional soil reinforcement method often relies on a large amount of cement, lime and other materials. The production process of these materials not only has high energy consumption, but also produces a large amount of CO2 emissions, which does not meet the development trend of green and low-carbon geotechnical engineering. In contrast, using CO2 mineralization technology for soil reinforcement can not only reduce the use of cement and other traditional building materials, but also achieve 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 a mineralized liquid that can be injected into soil to achieve soil carbon fixation, in-situ reinforcement of special soil and synergistic effect of soil carbon fixation and reinforcement. SUMMARY

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

[0006] To achieve the above purpose, the present application provides a soil carbon fixation-reinforcement synergistic system based on CO2 mineralization, which comprises a carbon alkali solution preparation device, a mineralized liquid injection device and a sampling and monitoring device.

[0007] The carbon alkali solution preparation device comprises a CO2 gas cylinder, a multi-stage filtration assembly and a reaction device. The CO2 gas cylinder is connected with the reaction device through a gas valve. The reaction device is connected with a stirrer and a pressure gauge. The reaction device is connected with the mineralized liquid injection device through the multi-stage filtration assembly.

[0008] The mineralizing liquid injection device comprises 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 machine, the air compressor is connected with the air pressure control box, the air pressure control box is connected in parallel with 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 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 jet drilling machine.

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

[0010] As a further scheme of the present application, the multi-stage filtering device comprises a first-stage vacuum filter and a second-stage vacuum filter, the first-stage vacuum filter and the second-stage vacuum filter are each divided into an upper part and a lower part, a replaceable filter membrane is arranged between the upper part and the lower part, and the upper part and the lower part are fixed through a detachable fixing frame.

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

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

[0013] As a further scheme of the present application, the pore size of the replaceable filter membrane of the first-stage vacuum filter is greater than the pore size of the replaceable filter membrane of the second-stage vacuum filter.

[0014] As a further scheme of the present application, the connection ends of the carbon alkali liquid storage tank and the calcium source liquid storage tank with the CO2 filter are respectively provided with an air valve one and an air valve two, and the connection ends of the carbon alkali liquid storage tank and the calcium source liquid storage tank with the rotary jet drilling machine are respectively provided with a liquid outlet valve one and a liquid outlet valve two.

[0015] As a further scheme of the present application, the rotary jet injection hole positions are distributed in a triangular hole distribution mode, and the monitoring wells are arranged at the center positions of the triangular distribution.

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

[0017] 1) The present application converts CO2 into mineralized liquid that can be injected and reinforce soil. Compared with traditional soil reinforcement methods, the present application highly integrates soil carbon sequestration and in-situ soil reinforcement. The application realizes the mineralization of exogenous CO2 in depth-controllable soil, thereby achieving the synergistic effect of soil carbon sequestration and reinforcement. According to the type and demand of soil, the present application can also realize soil carbon sequestration or soil reinforcement tracking. The present system realizes the fixation of CO2 in soil or the resource utilization of CO2 reinforced soil through the chemical phase transformation of CO2, which reduces the processing cost of CO2 and helps to achieve effective geological storage of CO2 to achieve carbon sequestration goals.

[0018] 2) The multi-stage filtration assembly uses replaceable filter membranes with different pore sizes for fractional filtration to effectively remove impurities generated during the reaction, ensuring the purity and stability of the carbon alkali solution. The replaceable filter membranes are easy to replace, clean and maintain.

[0019] 3) The system has high flexibility and adaptability. The ratio of carbon alkali solution and calcium source solution, injection speed and injection amount can be adjusted according to the actual situation and demand of soil to ensure the best carbon sequestration or reinforcement effect.

[0020] 4) The setting of the sampling and monitoring device enables the monitoring and evaluation of carbon sequestration or reinforcement parameters before and after treatment. This not only helps to accurately evaluate the carbon sequestration or reinforcement effect, but also optimizes the scheme and provides scientific basis for subsequent similar projects. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The present application is a whole schematic diagram of the soil carbon sequestration-reinforcement synergistic system based on CO2 mineralization.

[0022] Figure 2 The present application is a schematic diagram of the replaceable filter membrane and detachable fixing clamp at A. Figure 1

[0023] Figure 3 The present application is a position schematic diagram of the rotary jet injection hole, monitoring well and sampling area.

[0024] ​In the figure: 1, CO2 gas cylinder, 2, gas valve, 3, stirrer, 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 solution 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 solution storage tank, 24, liquid outlet valve two, 25, rotary jet drilling machine, 26, rotary jet injection hole, 27, resistivity and CO2 monitoring instrument, 28, monitoring well, 29, sampling area, 30, surface soil, 31, soil to be treated, 32, replaceable filter membrane, 33, detachable fixing frame. DETAILED DESCRIPTION

[0025] The application will be further described by examples.

[0026] As shown in Figure 1 and Figure 3 , a CO2 mineralization-based soil carbon sequestration-strengthening synergistic system includes a carbon alkali solution preparation device, a mineralization solution injection device, and a sampling and monitoring device; according to the type and requirements of the soil, CO2 is mineralized in the soil at a controllable depth to achieve soil carbon sequestration, or to achieve in-situ strengthening of the soil, or to achieve a synergistic effect of soil carbon sequestration and strengthening.

[0027] The mineralization solution is composed of carbon alkali solution and calcium source solution. The carbon alkali solution is obtained by filtering the reaction product of a metahydroxyaluminate solution with a concentration lower than 1 mol / L and CO2. The calcium source solution is a calcium salt that can react with the carbon alkali solution to form a precipitate, including but not limited to calcium chloride, and its concentration is consistent with that of the carbon alkali solution.

[0028] The carbon alkali solution preparation device includes a CO2 gas cylinder 1, a multi-stage filtration assembly, 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 to a stirrer 3 and a pressure gauge 4. The reaction device 5 is connected to the mineralization solution injection device through the multi-stage filtration assembly. The multi-stage filtration assembly and the reaction device 5 are fixed by a support frame 7. The gas valve 2 is used to control the gas inlet amount, and the stirrer 3 is used to make the metahydroxyaluminate solution and CO2 fully react in the reaction device 5. Then, the solution is filtered through the multi-stage filtration assembly to maintain the fluidity of the solution.

[0029] The mineralizing 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. The air compressor 20 is connected with the air pressure control box 19. The air pressure control box 19 is connected in parallel with 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 with a multi-stage filtering assembly. The carbon alkali liquid storage tank 16 and the calcium source liquid storage tank 23 are jointly connected with the rotary jet drilling machine 25. The CO2 filter 18 is filled with a solution capable of adsorbing CO2, including but not limited to sodium hydroxide solution.

[0030] The sampling monitoring device comprises monitoring wells 28 and resistivity and CO2 monitoring instruments 27. The monitoring wells 28 are arranged according to the rotary jet injection hole positions 26. Each rotary jet injection hole position 26 is provided with a sampling area 29.

[0031] In order to ensure the filtering effect of the multi-stage filtering device, further, as shown in Figure 1 and Figure 2 , the multi-stage filtering device comprises a first-stage vacuum filter 8 and a second-stage vacuum filter 11. Both the first-stage vacuum filter 8 and the second-stage vacuum filter 11 are divided into upper and lower parts. Replaceable filter membranes 32 are arranged between the upper and lower parts. The upper and lower parts are fixed through detachable fixing frames 33.

[0032] The first-stage vacuum filter 8 and the second-stage vacuum filter 11 are respectively connected with a vacuum pump one 14 and a vacuum pump two 12 through valves one 15 and two 13.

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

[0034] Further, the pore size of the replaceable filter membrane 32 of the first-stage vacuum filter 8 is larger than that of the replaceable filter membrane 32 of the second-stage vacuum filter 11. The pore size of the replaceable filter membrane 32 of the first-stage vacuum filter 8 can be 1 μm. The pore size of the replaceable filter membrane 32 of the second-stage vacuum filter 11 is between 0.2 μm and 0.45 μm, which ensures the effective removal of oxygen alumina particles generated in the reaction and maintains the fluidity of the solution.

[0035] Further, the connection ends of the carbon alkali liquid storage tank 16 and the calcium source liquid storage tank 23 with the CO2 filter 18 are respectively provided with air valves one 17 and two 22. The connection ends of the carbon alkali liquid storage tank 16 and the calcium source liquid storage tank 23 with the rotary jet drilling machine 25 are respectively provided with liquid outlet valves one 21 and two 24.

[0036] Further, as shown in Figure 3 The spin injection hole sites 26 are distributed in a triangular manner, the distance between adjacent spin injection hole sites 26 is 2-2.5 m, the monitoring well 28 is arranged at the center of the triangular distribution, and the sampling area 29 is 1-1.5 m away from the spin injection hole site 26.

[0037] The present application is used specifically:

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

[0039] 2. After the reaction device 5 reaches the predetermined amount of CO2, close the gas valve 2, open the stirrer 3, so that the metashilite solution and CO2 can fully react, and when the pressure gauge 4 shows a stable number and no more precipitate is generated, the reaction is completed;

[0040] 3. Open the liquid outlet control valve one 6 of the reaction device 5, close the liquid outlet control valve two 9 of the first-stage vacuum filter 8, open the vacuum pump one 14 and the valve one 15, so that the suspension after reaction enters the first-stage vacuum filter 8 for first-stage filtration, and the replaceable filter membrane 32 with a pore size of 1 μm can be selected for the first-stage vacuum filter 8;

[0041] 4. After the first-stage filtration is completed, close the vacuum pump one 14, the valve one 15 and the control valve three 10, open the control valve two 9, open the vacuum pump two 12 and the valve two 13, so that the solution after the first-stage filtration enters the second-stage vacuum filter 11 for second-stage filtration, and the replaceable filter membrane 32 with a pore size between 0.2 μm and 0.45 μm can be selected for the second-stage vacuum filter 11;

[0042] 5. After the second-stage filtration is completed, close the vacuum pump two 12 and the valve two 13, open the control valve three 10, put the carbon alkali liquid obtained after the two-stage filtration into the carbon alkali liquid storage tank 16, and configure the calcium source liquid into the calcium source liquid storage tank 23;

[0043] 6. Level the site and arrange the spin injection hole sites 26 in a triangular manner, the distance between adjacent spin injection hole sites 26 is 2-2.5 m, the monitoring well 28 is arranged at the center of the triangular distribution, and the sampling area 29 is 1-1.5 m away from the spin injection hole site 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, filter out 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 drill 25, inject and stir the carbon alkali liquid, the drilling speed of the rotary jet drill 25 is 0.5-1 m / min, the rotary speed is 10-15 r / min, and the injection speed of the carbon alkali liquid is 20-50 L / 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 liquid 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 liquid 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 drill 25 is 0.5-1 m / min, the reverse rotary speed is 10-15 r / min, the injection speed of the calcium source liquid is 20-50 L / 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 liquid outlet valve 24 of the calcium source liquid storage tank 23;

[0047] 10. Move the drill to the next rotary jet injection hole site 26, repeat steps 7-9 until all rotary jet injection hole sites 26 and the soil around them are effectively treated;

[0048] 11. 12h, 24h, 36h, 48h, 72h after the injection is completed, detect the conductivity of the treated area using the resistivity and CO2 monitoring instrument 27, and compare it with the detection data before the treatment to analyze the diffusion and migration of the CO2 mineralization liquid;

[0049] 12. Monitor the CO2 leakage in the field during and after the injection process through the resistivity and CO2 monitoring instrument 27;

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

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

[0052] 15、If the carbon sequestration-reinforcement synergistic process needs to be monitored, samples are taken from the sampling area 29 at 12h, 24h, 36h, 48h, 72h after injection, and control samples are taken from the non-injection area, and carbon sequestration parameters and reinforcement parameters are measured to verify the carbon sequestration-reinforcement synergistic effect.

Claims

1. A soil carbon sequestration and 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), an agitator (3) and a pressure gauge (4) are connected to the reaction device (5), and the reaction device (5) is connected to the mineralization liquid injection device via the multi-stage filtering component; The mineralizing 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 rig (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 the multi-stage filter assembly, and the carbon alkali liquid storage tank (16) and the calcium source liquid storage tank (23) are connected to the rotary jet drilling rig (25); The sampling and monitoring device includes a monitoring well (28), a resistivity and CO2 monitoring instrument (27), the monitoring well (28) is arranged according to the rotary jet injection hole position (26), and a sampling area (29) is provided around each rotary jet injection hole position (26); The multi-stage filtration assembly includes a primary vacuum filter (8) and a secondary vacuum filter (11), wherein the primary vacuum filter (8) and the secondary vacuum filter (11) are each divided into an upper portion and a lower portion, a replaceable filter membrane (32) is placed between the upper portion and the lower portion, and the upper portion and the lower portion are fixed by a detachable fixing frame (33); 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) respectively through the valve 1 (15) and the valve 2 (13); 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).

2. The soil carbon sequestration and reinforcement synergistic system based on CO2 mineralization according to claim 1 is characterized in that: The pore size of the replaceable filter membrane (32) of the first-stage vacuum filter (8) is larger than the pore size of the replaceable filter membrane (32) of the second-stage vacuum filter (11).

3. The soil carbon sequestration and reinforcement synergistic system based on CO2 mineralization according to claim 1 is characterized in that: The connection 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 1 (17) and an air valve 2 (22), and the connection 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).

4. A soil carbon sequestration and reinforcement synergistic system based on CO2 mineralization according to any one of claims 1 to 3, characterized in that: The rotary jet injection holes (26) are distributed in a triangular pattern, and the monitoring well (28) is located at the center of the triangular pattern.

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