Supercritical water gasification combined biomimetic seawater co2 / h2 separation method

Abstract

This invention discloses a biomimetic seawater separation method combining supercritical water gasification, relating to the field of biomimetic seawater separation and capture technology. It aims to address the current CO2 separation technology's lack of clear prediction of the relationship between the captured concentration and capture rate after syngas separation, its failure to clearly define the upper limit of the separation system, and the lack of clear calculation of the changes in capture flow rate and concentration with respect to capture parameters for the captured gas. The key technical solution comprises the following steps: S1: Biomimetic seawater generation; S2: Biomimetic seawater purification; A1: Calculating dissolved amounts: determining the dissolved amounts of each gas component in the biomimetic seawater and the undissolved amounts in the gas phase; A2: Calculating the separation upper limit: calculating the limit of the separation system based on the values ​​of the dissolved amounts of each gas component in the biomimetic seawater and the undissolved amounts in the gas phase; S3: Separation at atmospheric pressure; S4: Gas phase separation. This achieves lower separation energy consumption and less separation energy loss.

Description

Technical Field

[0001] This invention relates to biomimetic seawater In the field of separation and capture technology, particularly relating to a biomimetic seawater system combining supercritical water vaporization. Separation methods. Background Technology

[0002] To advance the "carbon peaking" and "carbon neutrality" policies, the carbon dioxide produced by the combustion or gasification of fossil fuels (… (This requires) capture and recycling. For clean fuel utilization, coal or biomass can be gasified in supercritical water. The process involves passing a coal-water slurry or biomass slurry into supercritical water to achieve high-temperature, high-pressure clean gasification. The final product is... , CO And the excess water generated during gasification, without the production of ash or other environmental pollutants (such as... , To achieve carbon capture, mature technologies currently include amine absorption, pressure swing adsorption, and membrane separation.

[0003] In the principles of thermodynamics Separation from a gas mixture inevitably requires additional energy consumption, and current methods for amine absorption and pressure swing adsorption... The separation energy consumption is too high (0.6~0.8 kW·h / kg-). The loss was also relatively large (0.3~0.6 kW·h / kg-). The efficiency according to the second law of thermodynamics is only ~10%; furthermore, the pressure of the syngas produced after supercritical water vaporization (≥22.1 MPa) is severely mismatched with the pressure of the amine absorption method or the pressure swing adsorption method (~2 MPa), while membrane separation methods... The pressure difference is in the kilopascal range, which is even more mismatched with the pressure of the supercritical water gasification products. Using these methods to directly separate the syngas produced by supercritical water gasification will inevitably cause pressure loss, thereby increasing the energy consumption required for separation.

[0004] The existing technical solutions mentioned above have the following drawbacks: In addition to excessive separation energy consumption, current CO2 separation technologies do not clearly predict the amount of CO2 captured after syngas separation. Concentration and The relationship between capture rate and separation rate is not clearly defined, nor is an upper limit specified for the separation system, and the capture rate is not explicitly defined. The changes in the capture flow rate and concentration of the gas with respect to the capture parameters were not clearly calculated. Summary of the Invention

[0005] The purpose of this invention is to provide a method for supercritical water gasification and high-pressure syngas separation. Low-energy capture and involving Biomimetic seawater combining supercritical water gasification with analysis of purity, capture rate, and energy consumption of separation and capture techniques. Separation methods.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A biomimetic seawater system combining supercritical water vaporization The separation method comprises the following steps:

[0008] S1: Biomimetic seawater generation involves feeding coal-water slurry into preheated supercritical water and using a fixed-bed reactor to complete rapid catalytic gasification. The generated syngas retains high pressure after cooling, and the pressure is the same as that of supercritical water gasification (~25MPa). Furthermore, the syngas contains a large amount of excess gasification water, which is the biomimetic seawater.

[0009] S2: Biomimetic seawater purification, where syngas and biomimetic seawater are introduced together into a high-pressure separator. Under high pressure, it will dissolve in large quantities in the biomimetic seawater, and and It is sparingly soluble in water and contains... The biomimetic seawater enters the atmospheric pressure separator along with the liquid level regulating valve;

[0010] A1: Calculate the amount of dissolved gas: When the syngas produced by supercritical water-coal gasification and the biomimetic seawater enter the high-pressure separator, it is first necessary to calculate the relationship between the partial pressure and solubility of each gas component in the syngas, and determine the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas in the gas phase.

[0011] A2: Calculate the upper limit of separation by calculating the limit of the separation system based on the values ​​of the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas components in the gas phase.

[0012] S3: Atmospheric pressure separation, in an atmospheric pressure separation tank, occurs due to a sudden pressure drop. Its solubility in water decreases sharply, and it dissolves in biomimetic seawater. It will completely precipitate, therefore a high concentration can be captured at the gas phase outlet of the low-pressure separator. gas;

[0013] S4: Gas phase separation: In a high-pressure separator, substances that are sparingly soluble in water... and Discharged through the gas phase outlet, low concentration can be obtained. Concentration of rich The fuel gas, at this point, has completed the supercritical water-coal gasification process for syngas. The capture and purification of fuel gas.

[0014] Furthermore, the specific steps for calculating the amount dissolved in A1 are as follows:

[0015] B1: In the high-pressure separator, the dissolved amounts of each component in the gasified syngas can be calculated through dissolution equilibrium. Furthermore, according to the ideal gas law, the molar ratio of each component is equal to its partial pressure ratio. Therefore, we can obtain:

[0016] (1)

[0017] (2)

[0018] (3)

[0019] In the formula, This represents the equilibrium constant of component i; This indicates the solubility of component i in water (unit: mol / L). The table shows the solubility of component i in water (in mol / kg) and its relationship with the partial pressure of the component. related; The percentage of component i in the gas phase. For the quality of water, The density of the solution; Let p be the partial pressure of component i in separator 1, and p be the total pressure.

[0020] Furthermore, since the high-pressure separator in B1 always operates at room temperature and does not require additional heating, it is assumed that the temperature in the high-pressure separator is always room temperature (25°C). At this time, the solubility-pressure function of each gas component under different pressures is obtained by fitting the electrolyte model and the CPA equation of state.

[0021] B2: In the data from supercritical water-coal gasification, the main components of the syngas are: and , It accounts for about 10%, while the remaining gaseous components (such as...) , , The proportion of solubility-pressure functions is less than 1% of the total, therefore the main fitting function is... and and Three gases:

[0022] (4)

[0023] (5)

[0024] (6)

[0025] In equations (4) to (6), the unit of gas partial pressure is bar, and the unit of solubility is mol / kg. The condition for equation (5) to hold is... ,when At room temperature It is in a liquid state, which does not match the gaseous model.

[0026] Furthermore, in B2, when the total pressure p in the high-pressure separator, the molar amount of each component in the syngas, and the mass of the biomimetic seawater are determined, the combined equations (1) to (6) can be used to solve for the gas phase partial pressure of each gas component in the high-pressure separator. Simultaneously, the amount of each gas component dissolved in the biomimetic seawater and the amount undissolved in the gas phase can be determined. The amount dissolved in the biomimetic seawater... When the pressure drops to normal atmospheric pressure, it can be considered that...

[0027] The relatively pure ones captured In the gas, the molar percentage of each component is: , The capture rate :

[0028] (7)

[0029] (8)

[0030] When the calculations show that each gas component is in a rich environment after high-pressure separation Fuel and capture After determining the specific molar amount, the upper limit of separation can be further predicted.

[0031] Furthermore, the specific steps for calculating the upper limit of separation in A2 are as follows:

[0032] C1: Add an extra pump to the high-pressure separation device to change the biomimetic seawater content in the high-pressure separation tank, and the pressure of the extra biomimetic seawater is equal to the separation pressure. Since the energy consumption of liquid compression is small, the electrical energy consumed by the pump is negligible.

[0033] C2: The lower limit of the biomimetic seawater mass in the high-pressure separator is the excess water from the gasification reaction. At this point, no additional biomimetic seawater is added to the separator, and the pump cannot add biomimetic seawater to the tank indefinitely. Therefore, the upper limit of the water volume is the sum of the maximum amount of biomimetic seawater added by the pump and the original amount of biomimetic seawater. The condition for the biomimetic seawater volume to reach its maximum is:

[0034] (9)

[0035] This means that when the input biomimetic seawater volume reaches its maximum value m*, the molar amount of each gas component in the gas phase is simultaneously 0. When the biomimetic seawater volume is slightly less than m*, there are component gases in the gas phase; while when the water volume is slightly greater than m*, the gas components dissolve in an unsaturated state. Therefore, the numerical solution of m* can be calculated through iteration.

[0036] To facilitate comparison of calculation results, the water-air ratio (rWG) is introduced:

[0037] (10)

[0038] The unit of water-to-gas ratio is kg / mol-Syngas, which represents the mass of biomimetic seawater in the high-pressure separator when a unit mole of syngas is input. The significance lies in unitizing the input gas and establishing the relationship between biomimetic seawater and syngas.

[0039] Furthermore, in C2, there is inevitably an upper limit to separation when the separation pressure and water-to-gas ratio change. Since the solubility of each gas component differs and is mutually restrictive, changes in separation pressure and water-to-gas ratio have the same effect on gas solubility. To simplify the analysis, the two variables of separation pressure and water-to-gas ratio are reduced to one variable, and a characteristic quantity ξ is introduced:

[0040] (11)

[0041] The characteristic quantity ξ is dimensionless and has energy characteristics. It represents the theoretical minimum power consumption required to separate a mixture of known components into two specific streams. The characteristic quantity ξ is independent of the amount of components and is called virtual work.

[0042] Furthermore, the virtual work ξ replaces the water-to-gas ratio and separation pressure, thereby reducing the dimensionality of the variables and representing the virtual work ξ corresponding to the same monotonic changing region. By combining the relationship between the capture rate and the CO2 capture concentration, the upper limit of separation can be determined. capture rate and The capture concentrations are mutually constrained on a single curve, and neither can reach its maximum value simultaneously. The advantage of using the virtual work characteristic is that it can eliminate specific constraints during analysis. When the separation effect is clear, appropriate separation conditions can be selected based on the known value of the virtual work ξ.

[0043] Furthermore, based on the virtual work ξ, the water-to-air ratio after the pressure reduction is deduced, thereby achieving the same separation effect by increasing the mass of the biomimetic seawater. And for the biomimetic seawater... The separation method consumes almost no energy during the syngas separation process. The energy cost of gas separation is only the depressurization of the high-pressure syngas to atmospheric pressure. This energy consumption due to pressure loss is the separation energy consumption, which is also the system's energy loss. The calculation formula is as follows:

[0044] (12)

[0045] Since the virtual work, after conversion at room temperature, becomes the theoretical minimum separation energy consumption, the efficiency of the system according to the second law of thermodynamics is:

[0046] (13)

[0047] By using an ultra-high pressure swing separation method, the rich gas content after gasification syngas separation was simulated. Fuel molar quantity and capture The molar quantity, defined as the virtual work characteristic quantity, reduces the number of variables in the system and predicts the system's performance in separation. The upper limit of separation at time and Capture concentration - The capture rate limit curve provides guidance for improving separation performance.

[0048] In summary, the beneficial technical effects of the present invention are as follows:

[0049] 1. Biomimetic seawater combining supercritical water vaporization The separation method utilizes ultra-high pressure swing separation to simulate the rich gas content after syngas separation. Fuel molar quantity and capture The molar quantity, defined as the virtual work characteristic quantity, reduces the number of variables in the system and predicts the system's performance in separation. The upper limit of separation at time and Capture concentration - The capture rate limitation curve provides guidance for improving separation performance. Additionally, the biomimetic seawater combined with supercritical water gasification... Compared with traditional amine absorption methods, the separation method consumes less energy, has less energy loss, and exhibits higher efficiency according to the second law of thermodynamics.

[0050] 2. Biomimetic seawater combining supercritical water vaporization The separation method can cleanly convert coal into hydrogen-rich syngas, and then separate the syngas into hydrogen-rich syngas using a room-temperature ultra-high pressure pressure swing separation process. Fuel gas and capture Gas, to achieve The captured "dual carbon" targets can also improve fuel purity and grade. By analyzing virtual work characteristics, the upper limit of separation is predicted, indicating that in a single separation... Capture concentration and There is a limiting relationship between the capture rate and the maximum value cannot be reached at the same time, which provides a theoretical basis for improving the separation performance and capture purity;

[0051] 3. Capture concentration and The limit curve for capture rate indicates that, at an appropriate capture rate... At the same time, it can significantly reduce separation energy consumption and work capacity loss (Δ ... What can be obtained when the capture rate is 80%? The purity of the captured gas is ≥80%, and the separation effect can be maintained at the same level (virtual work remains unchanged) by adjusting the separation pressure and the amount of biomimetic seawater added, making the separation method flexible. Under this separation effect, the separation energy consumption (equal to energy loss) is only 0.052 kW·h / kg. This is far lower than the separation energy consumption (0.6~0.8 kW·h / kg) of mature amine absorption methods. ) and loss (0.328 kW·h / kg- The efficiency of the second law of thermodynamics is as high as 34.1%, which is also much higher than that of the alcohol amine absorption method (~10%). Attached Figure Description

[0052] Figure 1 This is a diagram showing the separation results when no additional water is added according to the present invention;

[0053] Figure 2 This is a schematic diagram illustrating the maximum water-to-air ratio as a function of pressure according to the present invention.

[0054] Figure 3 The separation results are shown in the figure when additional biomimetic seawater is added to this invention.

[0055] Figure 4 This is a graph showing the relationship between the virtual work ξ of the present invention and the pressure and water-to-air ratio;

[0056] Figure 5 This is a schematic diagram illustrating the change in the virtual work ξ of the present invention;

[0057] Figure 6 The present invention provides virtual work ξ and capture. Concentration and Graph showing the relationship between capture rate and other parameters;

[0058] Figure 7 For the present invention Separation method for work capacity loss Cluster rate relationship diagram;

[0059] Figure 8 This is a schematic diagram of the biomimetic CO2 separation method of the present invention;

[0060] Figure 9 This is a flowchart of the overall separation method of the present invention;

[0061] Figure 10 A flowchart of the water pump separation method is added to this invention. Detailed Implementation

[0062] The present invention will be further described in detail below with reference to the accompanying drawings.

[0063] Reference Figure 9 and Figure 10 A biomimetic seawater system combining supercritical water vaporization The separation method comprises the following steps:

[0064] S1: Biomimetic seawater generation involves feeding coal-water slurry into preheated supercritical water and using a fixed-bed reactor to complete rapid catalytic gasification. The generated syngas retains high pressure after cooling, and the pressure is the same as that of supercritical water gasification (~25MPa). Furthermore, the syngas contains a large amount of excess gasification water, which is the biomimetic seawater.

[0065] S2: Biomimetic seawater purification, where syngas and biomimetic seawater are introduced together into a high-pressure separator. Under high pressure, it will dissolve in large quantities in the biomimetic seawater, and and It is sparingly soluble in water and contains... The biomimetic seawater enters the atmospheric pressure separator along with the liquid level regulating valve;

[0066] A1: Calculate the amount of dissolved gas: When the syngas produced by supercritical water-coal gasification and the biomimetic seawater enter the high-pressure separator, it is first necessary to calculate the relationship between the partial pressure and solubility of each gas component in the syngas, and determine the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas in the gas phase.

[0067] A2: Calculate the upper limit of separation by calculating the limit of the separation system based on the values ​​of the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas components in the gas phase.

[0068] S3: Atmospheric pressure separation, in an atmospheric pressure separation tank, occurs due to a sudden pressure drop. Its solubility in water decreases sharply, and it dissolves in biomimetic seawater. It will completely precipitate, therefore a high concentration can be captured at the gas phase outlet of the low-pressure separator. gas;

[0069] S4: Gas phase separation: In a high-pressure separator, substances that are sparingly soluble in water... and Discharged through the gas phase outlet, low concentration can be obtained. Concentration of rich The fuel gas, at this point, has completed the supercritical water-coal gasification process for syngas. The capture and purification of fuel gas.

[0070] A coal-water slurry is fed into preheated supercritical water, and rapid catalytic gasification is performed using a fixed-bed reactor. The resulting syngas, after cooling, retains its high-pressure characteristics, with a pressure similar to that of supercritical water gasification (~25 MPa). The syngas also contains a large amount of excess gasified water, referred to as biomimetic seawater. This syngas and biomimetic seawater enter a high-pressure separator. Because different gases have different solubilities in water, such as… It dissolves readily in water under high pressure, and and These substances are poorly soluble in water, therefore A large amount of it will dissolve in the biomimetic seawater and enter the atmospheric pressure separator through the level control valve. In the atmospheric pressure separator, due to the sudden pressure drop... Its solubility in water decreases sharply, and it dissolves in biomimetic seawater. It will completely precipitate, therefore a high concentration can be captured at the gas phase outlet of the low-pressure separator. Gases, while in high-pressure separators, those that are sparingly soluble in water... and Discharged through the gas phase outlet, low concentration can be obtained. Concentration of rich The fuel gas, at this point, has completed the supercritical water-coal gasification process for syngas. The capture and purification of fuel gas.

[0071] Predictive capture Concentration and The specific method for achieving capture rate is as follows:

[0072] Since the technology of supercritical water-coal gasification is mature and the gasification results are authoritative, and the results can be queried and have good repeatability when the type of water-coal slurry, the temperature and pressure of the gasification reaction are determined, no new model is established for supercritical water-coal gasification, and existing authoritative experimental results are used directly.

[0073] When the syngas produced by supercritical water-coal gasification and the biomimetic seawater enter the high-pressure separator, it is first necessary to calculate the relationship between the partial pressure and solubility of each gas component in the syngas, determine the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas in the gas phase, and then predict the upper limit of separation.

[0074] In a high-pressure separator, the dissolved amounts of each component in the gasified syngas can be calculated through dissolution equilibrium. Furthermore, based on the ideal gas law, the molar ratio of each component equals its partial pressure percentage. Therefore, we can obtain:

[0075] (1)

[0076] (2)

[0077] (3)

[0078] In the formula, This represents the equilibrium constant of component i; This indicates the solubility of component i in water (unit: mol / L). The table shows the solubility of component i in water (in mol / kg) and its relationship with the partial pressure of the component. related; The percentage of component i in the gas phase. For the quality of water, The density of the solution; Let p be the partial pressure of component i in separator 1, and p be the total pressure.

[0079] Since the high-pressure separator operates at ambient temperature without additional heating, it is assumed that the temperature inside the separator remains constant at room temperature (25°C). At this point, the solubility-pressure functions of each gas component under different pressures are fitted using an electrolyte model and the CPA equation of state, facilitating subsequent calculations. In authoritative data on supercritical water-coal gasification, the main components of the syngas are... and , It accounts for about 10%, while the remaining gaseous components (such as...) , , The proportion of (etc.) is less than 1%, therefore the main fitting solubility-pressure function is , and Three gases:

[0080] (4)

[0081] (5)

[0082] (6)

[0083] In equations (4) to (6), the unit of gas partial pressure is bar, and the unit of solubility is mol / kg. The condition for equation (5) to hold is... ,when At room temperature It is in a liquid state, which does not match the gaseous model.

[0084] When the total pressure p in the high-pressure separator, the molar amount of each component in the syngas, and the mass of the biomimetic seawater are determined, the combined equations (1) to (6) can be used to solve for the partial pressure of each gas component in the gas phase in the high-pressure separator. Simultaneously, the dissolved amount of each gas component in the biomimetic seawater and the undissolved amount in the gas phase can be determined. When the CO2 dissolved in the biomimetic seawater is reduced to atmospheric pressure, it can be considered that...

[0085] The relatively pure ones captured In the gas, the molar percentage of each component is: , The capture rate :

[0086] (7)

[0087] (8)

[0088] When the calculations show that each gas component is in a rich environment after high-pressure separation Fuel and capture After determining the specific molar amount, the upper limit of separation can be further predicted.

[0089] The quality of the biomimetic seawater affects the separation effect. For example, under the same pressure, the more biomimetic seawater there is, the more it dissolves. The larger the quantity, the corresponding The capture rate will also increase, in order to analyze the biomimetic seawater in The specific impact of the separation process involves adding an extra pump to the high-pressure separation device to change the biomimetic seawater content in the high-pressure separation tank. The pressure of the additional biomimetic seawater is equal to the separation pressure. Since the energy consumption of liquid compression is small, the electrical energy consumed by the pump is negligible.

[0090] The mass of biomimetic seawater in the high-pressure separator is limited, with a lower limit of excess water from the gasification reaction, at which point no additional biomimetic seawater is added. Simultaneously, the pump cannot add biomimetic seawater to the tank indefinitely, because an excess of biomimetic seawater would cause all syngas components to completely dissolve, rendering the separator meaningless. Therefore, the upper limit of the water volume is the sum of the maximum amount of biomimetic seawater added by the pump and the original amount of biomimetic seawater. The condition for reaching the maximum amount of biomimetic seawater is:

[0091] (9)

[0092] This means that when the input biomimetic seawater volume reaches its maximum value m*, the molar amount of each gas component in the gas phase is simultaneously 0. When the biomimetic seawater volume is slightly less than m*, there are component gases in the gas phase; while when the water volume is slightly greater than m*, the gas components dissolve in an unsaturated state. Therefore, the numerical solution of m* can be calculated through iteration.

[0093] To facilitate comparison of calculation results, the water-air ratio (rWG) is introduced:

[0094] (10)

[0095] The unit of water-to-gas ratio is kg / mol-Syngas, which represents the mass of biomimetic seawater in the high-pressure separator when a unit mole of syngas is input. The significance lies in unitizing the input gas and establishing the relationship between biomimetic seawater and syngas.

[0096] Intuitively, when the pressure in the high-pressure separator increases or additional biomimetic seawater is added, the biomimetic seawater absorbs... The amount will increase, which will lead to The capture rate increases, but at this time the biomimetic seawater absorbs... and The amount of other component gases will also increase, leading to capture. The concentration of syngas decreases, and in extreme cases, when the amount of biomimetic seawater added reaches its maximum, all syngas will dissolve in the biomimetic seawater, resulting in no gas at the H2-rich fuel outlet, while the captured syngas... The syngas is identical to the gas before separation, and the separation device becomes ineffective. Therefore, there is an upper limit to the separation when the separation pressure and water-to-gas ratio change. Since the solubility of each gas component differs and is mutually restrictive, changes in separation pressure and water-to-gas ratio will have the same effect on gas solubility. To simplify the analysis, the two variables of separation pressure and water-to-gas ratio are reduced to one variable, and a characteristic quantity ξ is introduced:

[0097] (11)

[0098] The characteristic quantity ξ is dimensionless and possesses energy properties. It represents the theoretical minimum energy consumption required to separate a known mixture of gases into two specific streams. Furthermore, the characteristic quantity ξ is independent of the amount of components. However, in biomimetic seawater... In the separation method, this part of the power consumption does not actually exist; it is just a hypothetical characteristic power consumption. Therefore, the characteristic quantity ξ can be called virtual work, which is convenient for subsequent analysis.

[0099] Since the solubility of each component of the syngas differs and there are mutual constraints between their solubilities, within the same region (ensuring that the virtual work ξ changes monotonically with the separation pressure or water-gas ratio), when the virtual work ξ is the same, the separated gas components are exactly the same. Therefore, the virtual work ξ can be used as a characteristic quantity of the system, freeing the system from the relationship between the water-gas ratio and the separation pressure, and simplifying the two factors into one factor in the analysis.

[0100] To calculate the limits of the separation system, virtual work ξ can be used to replace the water-to-gas ratio and separation pressure, thereby reducing the dimensionality of the variables. Furthermore, the virtual work ξ corresponding to the same monotonically changing region... capture rate and By combining the trapping concentration relationship, the upper limit of separation can be determined. capture rate and The capture concentrations are mutually constrained on a single curve, and neither can reach its maximum value simultaneously. Furthermore, the advantage of using the virtual work characteristic is that it eliminates specific constraints during analysis. When the separation effect is clear, the value of the virtual work ξ can be known, allowing for the selection of appropriate separation conditions. For example, if there is a pressure loss in the system, the separation pressure will decrease. In this case, the water-air ratio after the pressure decrease can be deduced from the virtual work, thereby achieving the same separation effect by increasing the mass of biomimetic seawater.

[0101] For biomimetic seawater and The separation method consumes almost no energy during the syngas separation process. The energy cost of gas separation is only the depressurization of the high-pressure syngas to atmospheric pressure. This energy consumption due to pressure loss is the separation energy consumption, which is also the system's energy loss. The calculation formula is as follows:

[0102] (12)

[0103] Since the virtual work, after conversion at room temperature, becomes the theoretical minimum separation energy consumption, the efficiency of the system according to the second law of thermodynamics is:

[0104] (13)

[0105] Pressure swing separation can simulate the rich gas content after syngas separation in gasification. Fuel molar quantity and capture The molar quantity, defined as the virtual work characteristic quantity, reduces the number of variables in the system and predicts the system's performance in separation. The upper limit of separation at time and Capture concentration - The capture rate limitation curve provides guidance for improving separation performance. Additionally, biomimetic seawater combined with supercritical water gasification... Compared to traditional amine absorption methods, this separation method consumes less energy, suffers less energy loss, and exhibits higher efficiency in accordance with the second law of thermodynamics.

[0106] Based on existing experimental data as a reference for the gasification reaction, in supercritical water gasification, the concentration of the pre-prepared coal-water slurry is taken as 10 wt%, and the mass ratio of coal-water slurry to water is taken as 1:2.57. The main gasification products are... , and ,and Other products, accounting for less than 1%, are considered negligible. Based on data obtained from the gasification of 1 kg of Hongliulin coal, the stream entering the separator contains 43.68 mol of... (32.68%), 77.48 mol (57.97%) and 12.50 mol (9.35%), while containing an additional 32.4232g of biomimetic seawater, which is consistent with typical supercritical water gasification results—carbon gasification efficiency is approximately 100%, and : : The ratio of the two samples was approximately 3:6:1, and the temperature was kept constant at 25 ℃ during the separation process.

[0107] When the pressure of supercritical water gasification is 250 bar, the separation pressure in the high-pressure separator can be 1~250 bar. Without adding additional biomimetic seawater, the separation results are as follows: Figure 1 As shown, without adding additional water: (a) after high-pressure separation, rich in... (a) Fuel component molar concentration and capture amount; (b) Capture (c) Molar concentration and capture amount of each component at the outlet; The maximum capture rate was 68.15%, at which point the separation pressure was 250 bar. The concentration was 84.78%;

[0108] Without adding additional biomimetic seawater, the water-to-gas ratio is 0.24 kg / mol-Syngas. When adding additional biomimetic seawater, the upper limit of the water-to-gas ratio needs to be determined first. According to equation (9), the water-to-gas ratio under different separation pressures is calculated iteratively. Figure 2 As shown, the water-to-gas ratio is extremely high at low pressure, and decreases sharply as the pressure increases. This is because the solubility of all gases increases significantly with increasing pressure, especially in the low-pressure region. When the separation pressure reaches 250 bar, the upper limit of the water-to-gas ratio is 3.73 kg / mol-Syngas.

[0109] When the pressure in the high-pressure separator changes along with the water-to-gas ratio, the H2-rich fuel outlet... concentration, Capture export Concentration and Capture rate such as Figure 3 As shown, with the addition of additional biomimetic seawater, the pressure and water-to-air ratio change as follows: (a) in the separated H2-rich fuel (a) concentration; (b) trapping (c) concentration; The capture rate increases with increasing separation pressure and water-to-gas ratio, resulting in a decrease in CO2 concentration in H2-rich fuel, thus achieving fuel purification. The increased capture rate meets the requirements of the "dual carbon" carbon capture strategy, and is beneficial to... Figure 3 (b) and Figure 3 (c) When the captured When the concentration increases, regardless of whether the separation pressure decreases or the water-to-air ratio decreases, the corresponding operating conditions will remain the same. The capture rates of all species decreased, which directly illustrates the decrease in capture rates. concentration and There are limitations on the capture rate;

[0110] The virtual work ξ of the separation system changes under different separation pressures and water-to-gas ratios as follows: Figure 4 As shown, it can be observed that within a certain region, the virtual work ξ changes monotonically with the separation pressure or water-to-gas ratio, and the virtual work graph has only one "ridge" line. That is, under the same pressure, the virtual work ξ has only one maximum value when the water-to-gas ratio changes. In the initial region (low pressure and low water-to-gas ratio), when the pressure increases or the water-to-gas ratio increases, the amount of dissolved gas increases, the separation effect improves, and the virtual work ξ also increases. This region is called the water-deficient region, corresponding to one side of the "mountain" in the virtual work graph. When too much biomimetic seawater is added, more component gases dissolve under high pressure, and the total gas phase decreases. In extreme cases, all gases dissolve completely, the separation device loses its function, and the virtual work ξ is 0. This region corresponds to the other side of the "mountain" in the virtual work graph, called the excess water region. In the excess water region, the separation effect weakens with the increase of pressure and water-to-gas ratio, so the virtual work ξ will decrease.

[0111] For example, Figure 5 (a) Relationship between separation pressure pH and water-to-gas ratio rWG when ξ=0.2; (b) Relationship between CO2 capture concentration and ξ; (c) Results at the ξ ridgeline. Figure 5 In (a), the dashed line represents the peak value of the virtual work, indicating that when the separation pressure and water-to-air ratio are determined, the maximum value of the virtual work is fixed. Furthermore, the "ridge" line representing the maximum virtual work divides the plane into two regions: the area below the dashed line is the water-deficient region, and the area above it is the water-excess region. Figure 5 In (a), the virtual work ξ = 0.2. Within the same region, when the pressure is constant, the water-to-air ratio is also constant. This transforms the two-dimensional problem into a one-dimensional one. Figure 5 As can be seen in (b), within the same region, when ξ is around 0.2, the trapping... The concentration is the same, and The capture rate is also the same. The fluctuation in the figure represents the calculation error caused when calculating the virtual work ξ;

[0112] When the separation pressure is low, the water vapor content is low, and ξ=0.2 corresponds to the water-deficient region, where capture... The concentration is 89%. The capture rate is 60%; however, as the separation pressure increases, the water-to-air ratio increases, and ξ=0.2 corresponds to the excess water zone, where the capture rate is lower. The concentration is 58%. The capture rate was 96%. Figure 5 (c) represents the value of the virtual work ξ at the "ridge," with a maximum value of 0.2655; the corresponding capture value at this point is... The concentration was 77.3%. The capture rate was 84.5%, and it was also found that when ξ was approximately equal, the separated components were approximately the same, which verified the previous analysis.

[0113] The virtual work ξ changes upon separation. capture rate and The relationship between capture concentration and virtual work is as follows: Figure 6 (a) and Figure 6 As shown in (b), Figure 6 (a) Virtual work ξ and (a) Relationship between capture rate; (b) Virtual work ξ and capture rate (c) Concentration relationship; (c) Trapping Concentration and The limiting curve between capture rates; (d) Capture rate and capture In regions where the concentration simultaneously satisfies 80%, the virtual work ξ corresponding to the same region... capture rate and The capture concentration relationship is plotted on a graph, such as... Figure 6 As shown in (c), the pentagram in the figure represents the separation result when the virtual work ξ reaches its maximum value. It can be observed that... capture rate and The capture concentrations are mutually constrained on a single curve, and neither can reach its maximum value simultaneously.

[0114] Furthermore, the advantage of using the virtual work characteristic quantity is that it frees us from specific constraints during analysis. When the separation effect is clear, the value of the virtual work ξ is known, allowing us to choose appropriate separation conditions. For example, to make... capture rate and When the capture concentration reaches 80%, it can be concluded that the excess water area cannot meet the requirements. Figure 6 (c) The curve below the pentagram), and the virtual work ξ value in the water-deficient area is between 0.261 and 0.263, so the specific separation conditions can be set for the region as follows. Figure 6As shown in (d), the desired conditions can be achieved within both the upper and lower limits. For example, when the pressure is 135 bar, the conditions can be met when the water-to-gas ratio is 0.7 kg / mol-Syngas; if the pressure drops to 90 bar, the water-to-gas ratio can be increased to 1 kg / mol-Syngas, which can also meet the separation effect. This has better adaptability in actual system design.

[0115] Figure 7 for Work capacity loss / efficiency loss in separation methods, biomimetic seawater The loss of work capacity (ΔΔ) in the separation method is much smaller than the ΔΔ loss in the amine absorption method. When the capture rate is 80%, biomimetic seawater The heat loss of the separation method is only 0.052 kW·h / kg- The absorption rate of alcohol amines is 0.328 kW·h / kg. ; and when When the capture rate reaches 90%, biomimetic seawater The efflux loss of the separation method increased to 0.067 kW·h / kg⁻¹. At this point, the energy loss from the amine absorption method reaches 0.372 kW·h / kg. ;

[0116] Figure 8 To mimic seawater The second law of thermodynamics for separation methods states that efficiency increases with... The graph showing the change in capture rate, in Figure 8 In the context of biomimetic CO2 separation devices, the efficiency of the system follows the second law of thermodynamics. The capture rate decreases monotonically, and... When the capture rate is moderate, the efficiency of the second law of thermodynamics changes relatively smoothly; while when... Once the capture rate exceeds 80%, the efficiency of the second law of thermodynamics drops sharply, especially for biomimetic applications. Separation device, when When the capture rate reaches 80%, the system's efficiency according to the second law of thermodynamics is 41.7%; while when the biomimetic CO2 separator captures 90% of the CO2... At that time, the efficiency of the system according to the second law of thermodynamics was 34.1%, which is much higher than the efficiency of the second law of thermodynamics of the amine absorption method (~10%).

[0117] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A biomimetic seawater system combining supercritical water vaporization The separation method is characterized by: The steps are as follows: S1: Biomimetic seawater generation involves feeding coal-water slurry into preheated supercritical water and using a fixed-bed reactor to complete rapid catalytic gasification. The generated syngas retains high pressure after cooling, and the pressure is the same as that of supercritical water gasification (~25MPa). Furthermore, the syngas contains a large amount of excess gasification water, which is the biomimetic seawater. S2: Biomimetic seawater purification, where syngas and biomimetic seawater are introduced together into a high-pressure separator. Under high pressure, it will dissolve in large quantities in the biomimetic seawater, and and It is sparingly soluble in water and contains... The biomimetic seawater enters the atmospheric pressure separator along with the liquid level regulating valve; A1: Calculate the amount of dissolved gas: When the syngas produced by supercritical water-coal gasification and the biomimetic seawater enter the high-pressure separator, it is first necessary to calculate the relationship between the partial pressure and solubility of each gas component in the syngas, and determine the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas in the gas phase. A2: Calculate the upper limit of separation by calculating the limit of the separation system based on the values ​​of the amount of each gas component dissolved in the biomimetic seawater and the amount of undissolved gas components in the gas phase. S3: Atmospheric pressure separation, in an atmospheric pressure separation tank, occurs due to a sudden pressure drop. Its solubility in water decreases sharply, and it dissolves in biomimetic seawater. It will completely precipitate, therefore a high concentration can be captured at the gas phase outlet of the low-pressure separator. gas; S4: Gas phase separation: In a high-pressure separator, substances that are sparingly soluble in water... and Discharged through the gas phase outlet, low concentration can be obtained. Concentration of rich The fuel gas, at this point, has completed the supercritical water-coal gasification process for syngas. The capture and purification of fuel gas.

2. A biomimetic seawater system combining supercritical water gasification as described in claim 1 The separation method is characterized by: The specific steps for calculating the amount of solubility in A1 are as follows: B1: In the high-pressure separator, the dissolved amounts of each component in the gasified syngas can be calculated through dissolution equilibrium. Furthermore, according to the ideal gas law, the molar ratio of each component is equal to its partial pressure ratio. Therefore, we can obtain: （1） （2） （3） In the formula, This represents the equilibrium constant of component i; This indicates the solubility of component i in water (unit: mol / L). The table shows the solubility of component i in water (in mol / kg) and its relationship with the partial pressure of the component. related; The percentage of component i in the gas phase. For the quality of water, The density of the solution; Let p be the partial pressure of component i in separator 1, and p be the total pressure.

3. A biomimetic seawater system combining supercritical water gasification as described in claim 2. The separation method is characterized by: Since the high-pressure separator in B1 always operates at room temperature and does not require additional heating, it is assumed that the temperature in the high-pressure separator is always room temperature (25°C). At this time, the solubility-pressure function of each gas component under different pressures is obtained by fitting the electrolyte model and the CPA equation of state. B2: In the data from supercritical water-coal gasification, the main components of the syngas are: and , It accounts for about 10%, while the remaining gaseous components (such as...) , , The proportion of solubility-pressure functions is less than 1% of the total, therefore the main fitting function is... and and Three gases: （4） （5） （6） In equations (4) to (6), the unit of gas partial pressure is bar, and the unit of solubility is mol / kg. The condition for equation (5) to hold is... ,when At room temperature It is in a liquid state, which does not match the gaseous model.

4. A biomimetic seawater system combining supercritical water gasification as described in claim 3. The separation method is characterized by: In B2, when the total pressure p in the high-pressure separator, the molar amount of each component in the syngas, and the mass of the biomimetic seawater are determined, the combined equations (1) to (6) can be used to solve for the gas phase partial pressure of each gas component in the high-pressure separator. Simultaneously, the dissolved amount of each gas component in the biomimetic seawater and the undissolved amount in the gas phase can be determined. When the pressure drops to normal atmospheric pressure, it can be considered that... The relatively pure ones captured In the gas, the molar percentage of each component is: , The capture rate : （7） （8） When the calculations show that each gas component is in a rich environment after high-pressure separation Fuel and capture After determining the specific molar amount, the upper limit of separation can be further predicted.

5. A biomimetic seawater system combining supercritical water gasification as described in claim 4. The separation method is characterized by: The specific steps for calculating the upper limit of separation in A2 are as follows: C1: Add an extra pump to the high-pressure separation device to change the biomimetic seawater content in the high-pressure separation tank, and the pressure of the extra biomimetic seawater is equal to the separation pressure. Since the energy consumption of liquid compression is small, the electrical energy consumed by the pump is negligible. C2: The lower limit of the biomimetic seawater mass in the high-pressure separator is the excess water from the gasification reaction. At this point, no additional biomimetic seawater is added to the separator, and the pump cannot add biomimetic seawater to the tank indefinitely. Therefore, the upper limit of the water volume is the sum of the maximum amount of biomimetic seawater added by the pump and the original amount of biomimetic seawater. The condition for the biomimetic seawater volume to reach its maximum is: （9） This means that when the input biomimetic seawater volume reaches the maximum value m*, the molar amount of each gas component in the gas phase is simultaneously 0. When the biomimetic seawater volume is slightly less than m*, there are component gases in the gas phase; while when the water volume is slightly greater than m*, the gas components dissolve in an unsaturated state. Therefore, the numerical solution of m* can be calculated through iteration. To facilitate comparison of calculation results, the water-air ratio (rWG) is introduced: （10） The unit of water-to-gas ratio is kg / mol-Syngas, which represents the mass of biomimetic seawater in the high-pressure separator when a unit mole of syngas is input. The significance lies in unitizing the input gas and establishing the relationship between biomimetic seawater and syngas.

6. A biomimetic seawater system combining supercritical water gasification as described in claim 5. The separation method is characterized by: In C2, there is inevitably an upper limit to separation when the separation pressure and water-to-gas ratio change. Since the solubility of each gas component differs and is mutually restrictive, changes in separation pressure and water-to-gas ratio have the same effect on gas solubility. To simplify the analysis, the two variables of separation pressure and water-to-gas ratio are reduced to one variable, and a characteristic quantity ξ is introduced: （11） The characteristic quantity ξ is dimensionless and has energy characteristics. It represents the theoretical minimum power consumption required to separate a mixture of known components into two specific streams. The characteristic quantity ξ is independent of the amount of components and is called virtual work.

7. A biomimetic seawater system combining supercritical water gasification as described in claim 6 The separation method is characterized by: The virtual work ξ replaces the water-gas ratio and separation pressure, thereby reducing the dimensionality of the variables and representing the virtual work ξ corresponding to the same monotonic changing region. By combining the relationship between the capture rate and the CO2 capture concentration, the upper limit of separation can be determined. capture rate and The capture concentrations are mutually constrained on a single curve, and neither can reach its maximum value simultaneously. The advantage of using the virtual work characteristic is that it can eliminate specific constraints during analysis. When the separation effect is clear, appropriate separation conditions can be selected based on the known value of the virtual work ξ.

8. A biomimetic seawater system combining supercritical water gasification as described in claim 7. The separation method is characterized by: Based on the virtual work ξ, the water-to-air ratio after pressure reduction is deduced, thereby achieving the same separation effect by increasing the mass of the biomimetic seawater. The separation method consumes almost no energy during the syngas separation process. The energy cost of gas separation is only the depressurization of the high-pressure syngas to atmospheric pressure. This energy consumption due to pressure loss is the separation energy consumption, which is also the system's energy loss. The calculation formula is as follows: （12） Since the virtual work, after conversion at room temperature, becomes the theoretical minimum separation energy consumption, the efficiency of the system according to the second law of thermodynamics is: （13） By using an ultra-high pressure swing separation method, the rich gas content after gasification syngas separation was simulated. Fuel molar quantity and capture The molar quantity, defined as the virtual work characteristic quantity, reduces the number of variables in the system and predicts the system's performance in separation. The upper limit of separation at time and Capture concentration - The capture rate limit curve provides guidance for improving separation performance.

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