An experimental method and device for directly evaluating the effect of gas separation by hydrate

Abstract

The application provides an experimental method and device for directly evaluating the gas separation effect of a gas hydrate method, and the device comprises a high-pressure container with a piston, a pressure sensor, a plunger pump, a valve, a gas flow meter, a gas storage tank, a visible tank, a water tank, a gas cylinder, a water tank, a safety valve and a fan; the high-pressure container with the piston is connected with pipeline I at the top, the pipeline I has two outlets, one of which is connected with one end of valve e, and the other outlet is connected with the safety valve; the other end of the valve e is connected with one end of pipeline II, and the other end of the pipeline II is divided into two branch pipes, one of which has two outlets, one of which is connected with valve f, and the other outlet is connected with one end of gas storage tank I; the other end of the gas storage tank I is connected with one end of pipeline III, and the other end of the pipeline III is connected with the gas cylinder. Through the experimental method and experimental device, the gas components and the total amount of gas in the hydrate phase can be directly determined.

Description

Technical Field

[0001] This invention belongs to the field of mechanics, and in particular relates to an experimental method and apparatus for directly evaluating the gas separation effect of the gas hydrate method. Background Technology

[0002] Research on various CO2 capture technologies is ongoing, among which the separation of carbon dioxide using gas hydrates has emerged as a highly advantageous method. In particular, the addition of promoters such as tetrabutylammonium bromide (TBAB), tetrahydrofuran (THP), and cyclopentane has significantly improved the formation pressure and temperature of gas hydrates. For example, Kamata et al. applied TBAB hydrates to study the separation of various binary and ternary gas mixtures, finding that TBAB is highly suitable for the purification and recovery of small molecule gases. Li Xiaosen et al.'s research showed that using tetrabutylammonium bromide (TBAB) as a promoter for the hydrate method to separate flue gas (N2 / CO2) can enrich the CO2 molar fraction in the mixed gas from 17.4% to 95%.

[0003] However, the current evaluation methods for the separation effect of gas hydrates are indirect evaluations, and the evaluation results have large errors. At present, the commonly used method is to measure the gas phase pressure before and after the formation of hydrates and calculate the number of moles of gas using the phase equilibrium equation. By analyzing the gas phase composition by chromatography, the number of moles of each component in the gas phase can be calculated. By comparing the number of moles of each component in the gas phase before and after the reaction, the gas composition in the hydrate phase can be obtained, and thus the separation effect of the gas can be known. Although the above methods can calculate the separation effect of hydrates, the calculation process will have a large error. The main sources of the error are: (1) The equation of state used to calculate the gas components in the gas phase will produce a certain error, and different equations of state have different error sizes. Choosing a reasonable equation of state will produce a certain error, and requires a very professional knowledge and ability in high-pressure fluid phase equilibrium. (2) Fluid phase equilibrium equations are usually very complex equations or equation sets, and their calculation process also requires a very complex process. It often requires the use of computer programming. The programming process is not only complex, but the calculation results will also produce a certain calculation error. In summary, the current evaluation method for the gas separation effect of hydrates is an indirect evaluation method. Although feasible, it has a certain degree of error and requires highly specialized technical skills to implement, which is not convenient for ordinary engineering technicians to operate.

[0004] Another commonly used evaluation method involves: after hydrate synthesis, analyzing the composition of the remaining gas phase using chromatography, then freezing the hydrate to -1°C to ensure it does not decompose during the evacuation of the remaining gas from the reactor. After evacuating the reactor and creating a vacuum, the reactor temperature is raised to 25°C to allow complete decomposition of the hydrate, followed by analysis of the gas composition to obtain the separation effect. However, it is worth noting that freezing the hydrate to -1°C does not guarantee complete non-decomposition, thus the accuracy of this method is somewhat questionable. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the existing technology. This invention proposes a method and apparatus that can directly measure the separation effect of gas hydrates. Through the experimental method and apparatus of this invention, the gas components and total amount of gas in the hydrate phase can be directly measured, so as to obtain the gas separation effect of hydrates very intuitively and accurately. Moreover, it does not require high technical skills from the operators and has great value for promotion and application.

[0006] The present invention adopts the following technical solution:

[0007] An experimental apparatus for directly evaluating the gas separation effect of hydrate method includes a high-pressure container with piston, a pressure sensor, a plunger pump, valves, a gas flow meter, a gas storage tank, a visual tank, a water tank, a gas cylinder, a water tank, a safety valve, and a blower.

[0008] The top of the high-pressure vessel with a piston is connected to pipeline I. Pipeline I has two outlets, one of which is connected to one end of valve e and the other outlet is connected to a safety valve. The other end of valve e is connected to one end of pipeline II. The other end of pipeline II splits into two branches. The first branch has two outlets, one of which is connected to valve f and the other outlet is connected to one end of gas storage tank I. The other end of gas storage tank I is connected to one end of pipeline III, and the other end of pipeline III is connected to a gas cylinder.

[0009] The outlet of the second branch pipe is connected to one end of valve h. The other end of valve h is connected to one end of the back pressure valve through pipe IV. The other end of the back pressure valve is connected to one end of gas flow meter II through pipe V. The other end of gas flow meter II is connected to one end of pipe VI. The other end of pipe VI is placed in the water tank.

[0010] The top of the high-pressure vessel with a piston is connected to valve d via pipe VII;

[0011] The bottom of the high-pressure vessel with a piston is connected to one end of pipe VIII, the other end of pipe VIII is connected to one end of valve a, the other end of valve a is connected to one end of pipe IX, and the other end of pipe IX is placed inside water tank I.

[0012] The bottom of the high-pressure vessel with a piston is connected to one end of pipe X. The other end of pipe X is connected to one end of valve c. The other end of valve c is connected to one end of pipe XI. The other end of pipe XI is connected to plunger pump I. The other end of plunger pump I is connected to one end of pipe XII. The other end of pipe XII is connected to one end of valve b. The other end of valve b is connected to one end of pipe i. The other end of pipe i is placed inside water tank I.

[0013] The top of the high-pressure vessel with a piston is connected to one end of pipe ii. Pipe ii has two branches. The first branch is connected to pressure sensor I, and the second branch is connected to one end of valve j. The other end of valve j is connected to one end of pipe iii. The other end of pipe iii has two outlets. One outlet is connected to one end of valve k. The other end of valve k is connected to gas flow meter I through pipe iv. The other outlet is connected to one end of a visual tank. The other end of the visual tank is connected to the top of gas storage tank II through pipe v.

[0014] The top of gas storage tank II is also connected to valve O via pipe ⅵ;

[0015] The top of gas storage tank II is connected to pressure sensor II via pipe ⅶ;

[0016] The top of gas storage tank II is connected to one end of valve l via pipe ⅷ. Valve l is connected to a blower via pipe ⅸ. The blower is connected to valve m via pipe ⅹ. Valve m is connected to the bottom of gas storage tank II via pipe a.

[0017] The bottom of gas storage tank II is connected to valve p via pipe b. Valve p is connected to one end of plunger pump II via pipe c. The other end of plunger pump II is connected to pipe d. Pipe d is placed inside water tank II. The bottom of gas storage tank II is connected to one end of valve n via pipe e. The other end of valve n is connected to one end of pipe f. The other end of pipe f is placed inside water tank II.

[0018] A high-pressure vessel with a piston consists of a chamber and a piston that moves up and down within the chamber. The piston divides the chamber into two parts, preventing fluid exchange between the two chambers. The upper chamber is used for experiments involving the separation of gas from hydrates, while the lower chamber is used to inject high-pressure liquid, forcing the piston to move upwards. The piston's function is to discharge the gas from the high-pressure vessel 1 at a constant pressure, thus maintaining the state of the hydrate (neither decomposing nor reforming).

[0019] Furthermore, the cavity wall forming the chamber has a circulating water jacket layer. The circulating water jacket layer on the lower side of the cavity wall is connected to the cooling water inlet, and the circulating water jacket layer on the upper side of the cavity wall is connected to the cooling water outlet. The top of the cavity is sealed by a flange cover.

[0020] Furthermore, gas storage tank II stores the gas produced by the decomposition of hydrates, and uses a fan to force gas mixing to achieve uniform distribution of gas components.

[0021] Furthermore, the function of gas flow meter I and gas flow meter II is to measure the amount of gas discharged from the high-pressure container 1 with piston.

[0022] Furthermore, the volume of gas storage tank II is much larger than that of the high-pressure vessel with a piston.

[0023] Furthermore, the back pressure valve maintains stable pressure inside the high-pressure container with the piston, enabling constant pressure discharge of gas from the high-pressure container with the piston, thereby preventing the hydrate from decomposing or reforming.

[0024] An experimental method for directly evaluating the gas separation effect of hydrate method includes:

[0025] Step 1. Hydrate Synthesis

[0026] Open valve a between the high-pressure container with piston and water tank I, close valve f, open the gas cylinder switch, and inject 0.5 MPa of gas into the upper chamber of the high-pressure container with piston through valve g, gas storage tank I, and valve e. This forces the piston to move to the bottom of the high-pressure container with piston. Close valve a, and discharge the gas from the high-pressure container with piston through valve d. Add the liquid used for hydrate synthesis into the high-pressure container with piston. Inject the gas to be separated (0.5 MPa) from the gas cylinder into the high-pressure container with piston through valves g and e, and then discharge it through valve f. Repeat this process three times to completely remove the air from the high-pressure container with piston. Finally, introduce the gas to be separated into the high-pressure container with piston until the specified pressure is reached, then stop. Close valve e, and control the temperature of the high-pressure container with piston by introducing cooling water into the circulating water jacket layer. Conduct the hydrate synthesis experiment according to the conventional hydrate synthesis method. Open valve f to discharge the gas from the first branch pipe of pipeline II and gas storage tank I, and then close valve f.

[0027] Step 2. Adjusting the back pressure valve opening

[0028] Completely close the back pressure valve, open valves g and h, and open the gas cylinder switch to make the pressure inside gas storage tank I higher than the pressure inside the high-pressure container with piston after hydrate synthesis. Close the gas cylinder switch and close valve g. Slowly open the back pressure valve. After gas flow meter II shows gas flowing out, continue to slowly increase the opening of the back pressure valve. The pressure in gas storage tank I will slowly decrease. Once the pressure in gas storage tank I is exactly equal to the gas phase pressure of the high-pressure container with piston, the back pressure valve opening adjustment is complete.

[0029] Step 3. Gas phase gas discharge

[0030] Open valves b and c at the bottom of the high-pressure container with piston, and open valves e and h. Start plunger pump I to inject high-pressure liquid into the lower chamber of the high-pressure container with piston, forcing the piston inside the container to move upward. At this time, liquid in the upper chamber of the high-pressure container with piston will continuously flow out through valves e and h, the back pressure valve, and gas flow meter II into the water tank. Once liquid appears at the outlet, it indicates that the gas inside the high-pressure container with piston has been completely expelled. Close valves e and h.

[0031] Step 4. Decomposition process of hydrates

[0032] Open valve j and close valve k to raise the water bath temperature in the circulating water jacket to a sufficiently high temperature to ensure that the hydrate can be completely decomposed. At this time, the gas produced by the decomposition of hydrate will flow through valve j into gas storage tank II. The volume of gas storage tank II is much larger than that of the high-pressure container with piston. After the hydrate has been completely decomposed, close valve j.

[0033] Step 5. Gas Composition and Gas Testing

[0034] Open valves l and m, and turn on the blower to promote thorough mixing of the gas in gas storage tank II, ensuring uniform gas distribution throughout the tank. After the blower has circulated for a period of time, open valve o to take a sample from the top gas sampling port and analyze its composition using chromatography. This composition corresponds to the gas composition of the hydrate phase. Open valve p at the bottom of gas storage tank II and valve k at the top of gas storage tank II, and turn on plunger pump II to inject liquid into gas storage tank II. The gas in gas storage tank II enters flow meter I through valve k to measure the gas volume. Once liquid is visible in the tank, turn off plunger pump II, close valves p and k, and open valves o and n to drain the liquid from gas storage tank II into water tank II.

[0035] Furthermore, in step 3, because the exhaust process is very slow and the pressure inside the high-pressure container with the piston is kept stable by the back pressure valve, the hydrate will not decompose or be further generated during this process, thus ensuring that the gas phase composition of the hydrate remains unchanged.

[0036] The beneficial effects of this invention are:

[0037] This invention overcomes the shortcomings of commonly used methods for evaluating the separation effect of gas hydrates, such as inaccuracy, poor reliability, and high technical requirements. This invention adopts a direct measurement method, which can greatly improve the accuracy and ease of operation in evaluating the gas separation of hydrates, and has important application value. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the device of the present invention;

[0039] Figure 2 The compressibility factor of a CH4 and CO2 mixture under different pressures at 25℃;

[0040] Figure 3 The compressibility factor of a N2 and CO2 mixture under different pressures at 25℃;

[0041] Figure 4 A comparison graph showing the molar amounts of CH4 and CO2 mixed gas in the hydrate phase calculated by different equations of state at 25℃ with experimental values;

[0042] Figure 5 This is a comparison graph showing the molar amounts of N2 and CO2 mixed gas in the hydrate phase calculated by different equations of state at 25℃ with experimental values.

[0043] In the diagram: 1-High-pressure container with piston, 2-Pressure sensor I, 3-Pressure sensor II, 4-Plunger pump I, 5-Plunger pump II, 6-Back pressure valve, 7-Gas flow meter I, 8-Gas flow meter II, 9-Gas storage tank I, 10-Gas storage tank II, 11-Visual tank, 12-Water tank, 13-Gas cylinder, 14-Water tank I, 15-Water tank II, 16-Safety valve, 17-Blower;

[0044] 18-Valve a, 19-Valve b, 20-Valve c, 21-Valve d, 22-Valve e, 23-Valve f, 24-Valve g, 25-Valve h, 26-Valve j, 27-Valve k, 28-Valve l, 29-Valve m, 30-Valve n, 31-Valve o, 32-Valve p. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] To address the shortcomings of commonly used methods for evaluating the gas separation effect of gas hydrates, such as inaccuracy, low reliability, and high technical requirements, this invention proposes an experimental method and apparatus for directly evaluating the gas separation effect of hydrates. This direct measurement method can greatly improve the accuracy and ease of operation in evaluating the gas separation effect of hydrates, and has significant application value.

[0047] Example

[0048] like Figure 1 As shown, an experimental apparatus for directly evaluating the gas separation effect of hydrate method includes a high-pressure container 1 with piston, a pressure sensor, a plunger pump, a valve, a gas flow meter, a gas storage tank, a visual tank 11, a water tank 12, a gas cylinder 13, a water tank, a safety valve 16, and a blower 17.

[0049] The top of the high-pressure vessel 1 with a piston is connected to pipeline I. Pipeline I has two outlets, one of which is connected to one end of valve e22 and the other outlet is connected to safety valve 16. The other end of valve e22 is connected to one end of pipeline II. The other end of pipeline II splits into two branches. The first branch has two outlets, one of which is connected to valve f23 and the other outlet is connected to one end of gas storage tank I9. The other end of gas storage tank I9 is ​​connected to one end of pipeline III. The other end of pipeline III is connected to gas cylinder 13.

[0050] The outlet of the second branch pipe is connected to one end of valve h25. The other end of valve h25 is connected to one end of back pressure valve 6 through pipe IV. The other end of back pressure valve 6 is connected to one end of gas flow meter II8 through pipe V. The other end of gas flow meter II8 is connected to one end of pipe VI. The other end of pipe VI is placed in water tank 12.

[0051] The top of the high-pressure vessel 1 with a piston is connected to valve d21 via pipe VII;

[0052] The bottom of the high-pressure container 1 with a piston is connected to one end of pipe VIII, the other end of pipe VIII is connected to one end of valve a18, the other end of valve a18 is connected to one end of pipe IX, and the other end of pipe IX is placed in water tank I14.

[0053] The bottom of the high-pressure vessel 1 with a piston is connected to one end of pipe X, the other end of pipe X is connected to one end of valve c20, the other end of valve c20 is connected to one end of pipe XI, the other end of pipe XI is connected to plunger pump I4, the other end of plunger pump I4 is connected to one end of pipe XII, the other end of pipe XII is connected to one end of valve b19, the other end of valve b19 is connected to one end of pipe i, and the other end of pipe i is placed inside water tank I14;

[0054] The top of the high-pressure container 1 with a piston is connected to one end of pipe ii. Pipe ii has two branches. The first branch is connected to the pressure sensor I2, and the second branch is connected to one end of valve j26. The other end of valve j26 is connected to one end of pipe iii. The other end of pipe iii has two outlets. One outlet is connected to one end of valve k27. The other end of valve k27 is connected to gas flow meter I7 through pipe iv. The other outlet is connected to one end of visual tank 11. The other end of visual tank 11 is connected to the top of gas storage tank II10 through pipe v.

[0055] The top of the gas storage tank II10 is also connected to valve O31 via pipe U;

[0056] The top of the gas storage tank II10 is connected to the pressure sensor II3 via pipe ⅶ;

[0057] The top of the gas storage tank II10 is connected to one end of valve l28 via pipe ⅷ. Valve l28 is connected to blower 17 via pipe ⅸ. Blower 17 is connected to valve m29 via pipe ⅹ. Valve m29 is connected to the bottom of gas storage tank II10 via pipe a.

[0058] The bottom of gas storage tank II10 is connected to valve p32 via pipe b19. Valve p32 is connected to one end of plunger pump II5 via pipe c20. The other end of plunger pump II5 is connected to pipe d21. Pipe d21 is placed inside water tank II15. The bottom of gas storage tank II10 is connected to one end of valve n30 via pipe e. The other end of valve n30 is connected to one end of pipe f23. The other end of pipe f23 is placed inside water tank II15.

[0059] The high-pressure container 1 with a piston consists of a chamber and a piston that moves up and down within the chamber. The piston divides the chamber into two parts, preventing fluid exchange between the two chambers. The upper chamber is used for experiments involving the separation of gas from gas hydrates, while the lower chamber is used to inject high-pressure liquid, forcing the piston to move upwards. The piston's function is to discharge the gas from the high-pressure container 1 at a constant pressure, thus maintaining the state of the hydrate (neither decomposing nor reforming).

[0060] Furthermore, the cavity wall forming the chamber has a circulating water jacket layer. The circulating water jacket layer on the lower side of the cavity wall is connected to the cooling water inlet, and the circulating water jacket layer on the upper side of the cavity wall is connected to the cooling water outlet. The top of the cavity is sealed by a flange cover.

[0061] Furthermore, gas storage tank II10 stores the gas produced by the decomposition of hydrates, and a fan is used to force gas mixing to achieve a uniform distribution of gas components. Furthermore, gas flow meters I7 and II8 measure the amount of gas discharged from the high-pressure container 1 with a piston.

[0062] Furthermore, the volume of the gas storage tank II10 is much larger than that of the high-pressure container 1 with a piston.

[0063] Furthermore, the back pressure valve 6 is used to maintain the pressure stability inside the high-pressure container 1 with piston, so as to achieve constant pressure discharge of gas from the high-pressure container 1 with piston, thereby preventing the hydrate from decomposing or regenerating.

[0064] An experimental method for directly evaluating the gas separation effect of hydrate method includes:

[0065] Step 1. Hydrate Synthesis

[0066] Open valve a18 between the high-pressure container 1 with piston and water tank I14, close valve f23, open the gas cylinder 13 switch, and inject 0.5 MPa of gas into the upper chamber of the high-pressure container 1 with piston through valve g24, gas storage tank I9, and valve e22. This forces the piston to move to the bottom of the high-pressure container 1 with piston. Close valve a18, discharge the gas in the high-pressure container 1 with piston through valve d21, and add liquid for hydrate synthesis into the high-pressure container 1 with piston. Inject the gas to be separated (0.5 MPa) into the high-pressure container 1 with piston from gas cylinder 13 through valves g24 and e22, and then discharge it through valve f23. Repeat this process three times to completely remove the air from the high-pressure container 1 with piston. Finally, introduce the gas to be separated into the high-pressure container 1 with piston until the specified pressure is reached, then stop. Close valve e22, control the temperature of high pressure vessel 1 with piston by introducing cooling water into the circulating water jacket of high pressure vessel 1 with piston, conduct hydrate synthesis experiment according to conventional hydrate synthesis method, open valve f23 to purge the gas in the first branch pipe of pipeline II and gas storage tank I 9, and close valve f23.

[0067] Step 2. Adjusting the back pressure valve opening

[0068] Completely close back pressure valve 6, open valves g24 and h25, and open the switch for gas cylinder 13 to make the pressure inside gas storage tank I9 higher than the pressure inside the high-pressure container 1 with piston after hydrate synthesis. Close the switch for gas cylinder 13 and close valve g24. Slowly open back pressure valve 6. After gas flow meter II8 shows gas flowing out, continue to slowly increase the opening of back pressure valve 6. The pressure in gas storage tank I9 will slowly decrease. Once the pressure in gas storage tank I9 is ​​exactly equal to the gas phase pressure of high-pressure container 1 with piston, the opening of back pressure valve 6 is adjusted.

[0069] Step 3. Gas phase gas discharge

[0070] Open valves b19 and c20 at the bottom of the high-pressure container 1 with piston, and open valves e22 and h25. Start the plunger pump I4 to inject high-pressure liquid into the lower chamber of the high-pressure container 1 with piston, forcing the piston inside the container 1 to move upward. At this time, liquid in the upper chamber of the high-pressure container 1 with piston will continuously flow out through valves e22, h25, back pressure valve 6, and gas flow meter II8 into the water tank 12. Once liquid appears at the outlet, it indicates that the gas inside the high-pressure container 1 with piston has been completely discharged. Close valves e22 and h25.

[0071] Step 4. Decomposition process of hydrates

[0072] Open valve J26 and close valve K27 to raise the water bath temperature in the circulating water jacket to a sufficiently high temperature to ensure that the hydrate can be completely decomposed. At this time, the gas produced by the decomposition of hydrate will flow through valve J26 into gas storage tank II10. The volume of gas storage tank II10 is much larger than that of high-pressure container 1 with piston. After the hydrate has been completely decomposed, close valve J26.

[0073] Step 5. Gas Composition and Gas Testing

[0074] Open valves l28 and m29, and turn on fan 17 to promote thorough mixing of the gas in gas storage tank II 10, ensuring uniform gas distribution throughout the tank. After fan 17 circulates for a period of time, open valve o31 to take a sample from the top gas sampling port and analyze its composition using chromatography. This composition corresponds to the gas composition of the hydrate phase. Open valve p32 at the bottom of gas storage tank II 10 and valve k27 at the top, and turn on plunger pump II 5 to inject liquid into gas storage tank II 10. The gas in gas storage tank II 10 enters gas flow meter I 7 through valve k27 to measure the gas volume. Once liquid is present in the visible tank 11, turn off plunger pump II 4, close valves p32 and k27, and open valve o31 and n30 to drain the liquid from gas storage tank II 10 into water tank II 15.

[0075] Furthermore, in step 3, because the exhaust process is very slow and the pressure inside the high-pressure container 1 with the piston is kept stable by the back pressure valve 6, the hydrate will not decompose or be further generated during this process, thus ensuring that the gas phase composition of the hydrate remains unchanged.

[0076] The apparatus and method of this invention can accurately measure the effect of gas separation by the gas hydrate method and the gas composition in the hydrate phase, which improves the accuracy of measurement and reduces the professional technical requirements of operators, thus having significant application value.

[0077] For the CH4 and CO2 binary system, the compressibility factor under different pressures was calculated using the PR equation of state, BWRS equation of state, RK-SOAVE equation of state, PRMHV2 equation of state, and WER-LS equation of state, respectively. Figure 2As shown in the figure, when the pressure is low, the compressibility factors calculated by various equations of state are not significantly different. However, as the pressure increases, the difference in calculated compressibility factors gradually increases. For example, at 25℃ and 100 Bar, the compressibility factor calculated using the RK-SOAVE equation of state is 0.698, while the compressibility factor calculated using the PRMHV2 equation of state is 0.628, with a calculation error reaching 10%. Similarly, for a mixture of N2 and CO2 gases, the calculated compressibility factors differ considerably when using different equations of state. Figure 3 As shown, determining which equation of state to use requires a high level of expertise in chemical engineering. However, the apparatus of this invention eliminates these complex calculations and yields more accurate test results.

[0078] The convenience and accuracy of the method and apparatus of the present invention will be briefly demonstrated below with two examples.

[0079] CH4-CO2 system: In a 300mL blind reactor, 100mL of water was added, and the pressure of the CH4 and CO2 mixture inside the reactor was reduced from 80Bar to 30Bar. The molar amount of hydrate indirectly calculated using five equations of state and the experimentally measured molar amount are as follows: Figure 4 As shown in the figure, the molar quantity directly measured in the experiment is similar to the calculation results of the RK-SOAVE and BWRS equations of state, but differs significantly from the results of the other three equations of state.

[0080] CO2-N2 system: In a 300 mL blind reactor, 100 mL of water was added, and the pressure of the N2 and CO2 mixture inside the reactor was reduced from 80 Bar to 30 Bar. The molar amount of hydrate indirectly calculated using five equations of state and the experimentally measured molar amount are as follows: Figure 5 As shown in the figure, the molar quantity directly measured in the experiment is similar to the calculation result of the RK-SOAVE equation of state, but differs significantly from the results of the other four equations of state.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications 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.

Claims

1. An experimental apparatus for directly evaluating the gas separation effect of hydrate method, characterized in that, This includes high-pressure containers with pistons, pressure sensors, plunger pumps, valves, gas flow meters, gas storage tanks, visual tanks, water tanks, gas cylinders, water containers, safety valves, and fans; The top of the high-pressure vessel with a piston is connected to pipeline I. Pipeline I has two outlets, one of which is connected to one end of valve e, and the other outlet is connected to a safety valve. The other end of valve e is connected to one end of pipeline II. The other end of pipeline II splits into two branches, the first of which has two outlets. One outlet is connected to valve f, and the other outlet is connected to one end of gas storage tank I. The other end of gas storage tank I is connected to one end of pipeline III, and the other end of pipeline III is connected to a gas cylinder. The outlet of the second branch pipe is connected to one end of valve h. The other end of valve h is connected to one end of the back pressure valve through pipe IV. The other end of the back pressure valve is connected to one end of gas flow meter II through pipe V. The other end of gas flow meter II is connected to one end of pipe VI. The other end of pipe VI is placed in the water tank. The top of the high-pressure vessel with a piston is connected to valve d via pipe VII; The bottom of the high-pressure vessel with a piston is connected to one end of pipe VIII, the other end of pipe VIII is connected to one end of valve a, the other end of valve a is connected to one end of pipe IX, and the other end of pipe IX is placed in water tank I. The bottom of the high-pressure vessel with a piston is connected to one end of pipe X. The other end of pipe X is connected to one end of valve c. The other end of valve c is connected to one end of pipe XI. The other end of pipe XI is connected to plunger pump I. The other end of plunger pump I is connected to one end of pipe XII. The other end of pipe XII is connected to one end of valve b. The other end of valve b is connected to one end of pipe i. The other end of pipe i is placed inside water tank I. The top of the high-pressure vessel with a piston is connected to one end of pipe ii. Pipe ii has two branches. The first branch is connected to pressure sensor I, and the second branch is connected to one end of valve j. The other end of valve j is connected to one end of pipe iii. The other end of pipe iii has two outlets. One outlet is connected to one end of valve k. The other end of valve k is connected to gas flow meter I through pipe iv. The other outlet is connected to one end of a visual tank. The other end of the visual tank is connected to the top of gas storage tank II through pipe v. The top of gas storage tank II is also connected to valve O via pipeline ⅵ; The top of gas storage tank II is connected to pressure sensor II via pipe ⅶ; The top of gas storage tank II is connected to one end of valve l via pipe ⅷ. Valve l is connected to a blower via pipe ⅸ. The blower is connected to valve m via pipe ⅹ. Valve m is connected to the bottom of gas storage tank II via pipe a. The bottom of gas storage tank II is connected to valve p via pipe b. Valve p is connected to one end of plunger pump II via pipe c. The other end of plunger pump II is connected to pipe d. Pipe d is placed inside water tank II. The bottom of gas storage tank II is connected to one end of valve n via pipe e. The other end of valve n is connected to one end of pipe f. The other end of pipe f is placed inside water tank II. A high-pressure vessel with a piston consists of a chamber and a piston that moves up and down within the chamber. The piston divides the chamber into two, preventing the exchange of fluids between the two chambers. The chamber above the piston is used for experiments involving the separation of gas hydrates from gases, while the chamber below the piston is used to inject high-pressure liquid, thereby forcing the piston to move upward.

2. The experimental apparatus for directly evaluating the gas separation effect of the hydrate method according to claim 1, characterized in that, The cavity wall has a circulating water jacket layer. The circulating water jacket layer on the lower side of the cavity wall is connected to the cooling water inlet, and the circulating water jacket layer on the upper side of the cavity wall is connected to the cooling water outlet. The top of the cavity is sealed by a flange cover.

3. The experimental apparatus for directly evaluating the gas separation effect of the hydrate method according to claim 1, characterized in that, Gas storage tank II stores the gas produced by the decomposition of hydrates and uses a fan to force the gas to mix.

4. The experimental apparatus for directly evaluating the gas separation effect of the hydrate method according to claim 1, characterized in that, Gas storage tank II has a volume much larger than a high-pressure vessel with a piston.

5. An experimental method using the experimental apparatus for directly evaluating the gas separation effect of the hydrate method according to any one of claims 1-4, characterized in that, include: Step 1. Hydrate Synthesis A. Open valve a between the high-pressure container with piston and water tank I, close valve f, open the gas cylinder switch, and inject 0.5MPa of gas into the upper chamber of the high-pressure container with piston through valve g, gas storage tank I and valve e, forcing the piston to move to the bottom of the high-pressure container with piston; B. Close valve a, discharge the gas from the high-pressure container with piston through valve d, and add the liquid for hydrate synthesis to the high-pressure container with piston. Inject the gas to be separated into the high-pressure container with piston at 0.5 MPa from the gas cylinder through valves g and e, and then discharge it through valve f. Repeat this process 3 times to completely remove the air from the high-pressure container with piston. C. Finally, introduce the gas to be separated into the high-pressure container with piston, and stop when the specified pressure is reached. Close valve e. Control the temperature of the high-pressure container with piston by introducing cooling water into the circulating water jacket layer of the high-pressure container with piston. Carry out the hydrate synthesis experiment according to the conventional hydrate synthesis method. Open valve f to purge the gas in the first branch pipe of pipeline II and gas storage tank I, and close valve f. Step 2. Adjusting the back pressure valve opening Completely close the back pressure valve, open valves g and h, open the gas cylinder switch, so that the pressure in gas storage tank I is higher than the pressure in the high-pressure container with piston after hydrate synthesis. Close the gas cylinder switch, close valve g, and slowly open the back pressure valve. After the gas flow meter II shows that gas is flowing out, continue to slowly increase the opening of the back pressure valve. The pressure in gas storage tank I will slowly decrease. When the pressure value in gas storage tank I is exactly equal to the gas phase pressure of the high-pressure container with piston, the back pressure valve opening adjustment is complete. Step 3. Gas phase gas discharge Open valves b and c at the bottom of the high-pressure container with piston, open valves e and h, start plunger pump I, inject high-pressure liquid into the lower chamber of the high-pressure container with piston, forcing the piston in the high-pressure container to move upward. At this time, the liquid in the upper chamber of the high-pressure container with piston will continuously flow out into the water tank through valves e, h, back pressure valve and gas flow meter II. After liquid appears at the outlet, it indicates that the gas in the high-pressure container with piston has been completely discharged. Close valves e and h. Step 4. Decomposition process of hydrates Open valve j and close valve k to raise the water bath temperature in the circulating water jacket to a sufficiently high temperature to ensure complete decomposition of the hydrate. At this time, the gas produced by the decomposition of the hydrate will flow through valve j into gas storage tank II. The volume of gas storage tank II is much larger than that of the high-pressure container with piston. After the hydrate has completely decomposed, close valve j. Step 5. Gas Composition and Gas Testing Open valves l and m, and turn on the blower to promote thorough mixing of the gas in gas storage tank II, ensuring uniform gas distribution throughout the tank. After the blower circulates for a period of time, open valve o to take a sample from the top gas sampling port and analyze the gas composition using chromatography. This composition is the gas composition of the hydrate phase. Open valve p at the bottom of gas storage tank II and valve k at the top of gas storage tank II, and turn on plunger pump II to inject liquid into gas storage tank II. The gas in gas storage tank II enters flow meter I through valve k to measure the gas volume. Once liquid is visible in the tank, turn off plunger pump II, close valves p and k, and open valve o and valve n to drain the liquid from gas storage tank II into water tank II.

6. The method according to claim 5, characterized in that, Step 3: Because the exhaust process is very slow and the pressure inside the high-pressure container with the piston is kept stable by the back pressure valve, the hydrate will not decompose or be further generated during this process, thus ensuring that the gas phase composition of the hydrate remains unchanged.

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