Four-bed vacuum temperature swing adsorption process and device for separating CO2 in flue gas of power plant

Abstract

The invention discloses a four-bed vacuum temperature swing adsorption process and device for separating CO2 in flue gas of a power plant, and relates to the technical field of carbon dioxide adsorption.The four-bed vacuum temperature swing adsorption process comprises the following steps that S1, four adsorption beds are arranged on a four-bed adsorption ring, the four-bed adsorption ring is rotated, and the four-bed adsorption ring is rotated; enabling the four adsorption beds to circulate in a vacuum low-temperature adsorption station, a waiting station, a heating separation station and a cooling station on the vacuum temperature swing adsorption mechanism in sequence; s2, power plant flue gas is introduced into a vacuum low-temperature adsorption station, the vacuum low-temperature adsorption station enables an adsorption bed in the vacuum low-temperature adsorption station to generate a vacuum low-temperature environment, and meanwhile, when a four-bed adsorption ring rotates, an adsorption bed in a cooling station is pre-cooled; the four adsorption beds on the four-bed adsorption ring can circularly perform adsorption, desorption and regeneration operations, the high-temperature state and the low-temperature state of the flue gas of the power plant are repeatedly utilized in the whole adsorption process, and the treatment energy consumption of separation of CO2 in the flue gas of the power plant is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide adsorption, and in particular to a four-bed vacuum temperature swing adsorption process and device for separating CO2 from flue gas in power plants. Background Art

[0002] The vacuum temperature swing adsorption process refers to the process of adsorption at low or normal temperature and desorption at elevated temperature. In addition to adsorption and desorption, the entire temperature swing adsorption operation also includes auxiliary steps such as drying and cooling the adsorbent after desorption. Temperature swing adsorption is used for dehumidification of atmospheric pressure gas and air, recovery of solvent vapor in the air, etc. Since the flue gas of power plants contains a large amount of carbon dioxide, which does not meet the standard for direct emission, the vacuum temperature swing adsorption process can be used to adsorb carbon dioxide in the flue gas of power plants;

[0003] Existing carbon dioxide vacuum temperature swing adsorption processes, such as the carbon dioxide adsorption system disclosed in patent publication number CN118526923A and a low-pressure and low-energy flue gas carbon dioxide recovery system and recovery process disclosed in patent publication number CN117101335A, have long carbon dioxide vacuum temperature swing adsorption process flows and require a lot of equipment, resulting in high carbon dioxide adsorption costs and being unfavorable for use. Summary of the invention

[0004] In order to overcome the above-mentioned technical problems, the purpose of the present invention is to provide a four-bed vacuum temperature swing adsorption process and device for separating CO2 from power plant flue gas, so as to solve the problem in the prior art that the carbon dioxide vacuum temperature swing adsorption process has a long process flow, requires a lot of equipment, and the manufacturer has to invest a lot before deployment, resulting in high carbon dioxide treatment costs.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The first aspect of the present invention is to provide a four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant, comprising the following steps:

[0007] S1: four adsorption beds are arranged on a four-bed adsorption ring, and the four-bed adsorption ring is rotated so that the four adsorption beds are sequentially cycled in a vacuum low-temperature adsorption station, a waiting station, a heating separation station and a cooling station on the vacuum temperature swing adsorption mechanism;

[0008] S2: The vacuum low-temperature adsorption station creates a vacuum low-temperature environment for the adsorption bed therein, and at the same time, when the four-bed adsorption ring rotates, the adsorption bed in the cooling station is pre-cooled;

[0009] S3: The adsorption bed in the vacuum low-temperature adsorption station is transferred to the waiting station, where the adsorption bed is preheated;

[0010] S4: the adsorption bed in the waiting station is transferred to the heating separation station, and the heating separation station performs heating and decompression operation on the adsorption bed therein;

[0011] S5: the adsorption bed in the heating and separation station is transferred to the cooling station, and the cooling station performs a cooling operation on the adsorption bed therein;

[0012] S5: Repeat S1 to S6 until the flue gas from the power plant is completely adsorbed.

[0013] As a further solution of the present invention: Step S1 comprises the following steps:

[0014] S1.1: The flue gas from the power plant is pressurized by a compressor, and the high-pressure flue gas from the power plant is transported to the high-pressure pipeline. The high-pressure pipeline passes through the waiting station and performs heat exchange operation with the adsorption bed therein. The flue gas from the high-pressure power plant is automatically cooled to room temperature in the high-pressure pipeline;

[0015] S2.2: The flue gas from the high-voltage power plant passes through the high-voltage pipeline and passes through the waiting station to perform heat exchange operation with the adsorption bed therein;

[0016] S2.3: The high-voltage power plant flue gas after the waiting station is automatically cooled to room temperature in the high-voltage pipeline;

[0017] S2.4: Use a vacuum pump to extract the low-temperature gas in the vacuum low-temperature adsorption station to form a negative pressure in the environment of the vacuum low-temperature adsorption station;

[0018] S2.5: The vacuum pump transports the low-temperature gas sucked from the vacuum low-temperature adsorption station to the cooling station;

[0019] S2.6: Use a throttle valve to transport the high-voltage power plant flue gas in the high-voltage pipeline to the vacuum low-temperature adsorption station. The high-voltage power plant flue gas is rapidly depressurized and absorbs heat in the vacuum low-temperature adsorption station, so that the environment in the vacuum low-temperature adsorption station forms a low-temperature negative pressure;

[0020] S2.7: The pressure value of the environment in the vacuum low-temperature adsorption station is controlled by a throttle valve. When the pressure value of the environment in the vacuum low-temperature adsorption station reaches a preset pressure threshold, the introduction of high-voltage power plant flue gas into the vacuum low-temperature adsorption station is stopped.

[0021] As a further solution of the present invention: when the adsorption bed in the four-bed adsorption ring enters the vacuum low-temperature adsorption station from the cooling station, the vacuum low-temperature adsorption station reduces the pressure of the adsorption bed in the cooling station, and further cools the adsorption bed in the cooling station.

[0022] As a further solution of the present invention: the step S4 comprises the following steps:

[0023] S4.1: transfer the adsorption beds in the four-bed adsorption ring corresponding to the waiting station to the heating separation station;

[0024] S4.2: heating the adsorption beds in the four-bed adsorption ring to 60 degrees Celsius to 100 degrees Celsius by means of a heating device in the heating separation station, so as to desorb carbon dioxide in the adsorption beds;

[0025] S4.3: Use a vacuum pump to extract the desorbed carbon dioxide in the heating separation station and pump the carbon dioxide into a gas cylinder for storage.

[0026] As a further solution of the present invention: the step S5 comprises the following steps:

[0027] S5.1: transferring the adsorption beds in the corresponding four-bed adsorption ring after heating and decompression in the heating and separation station to the cooling station;

[0028] S5.2: The adsorption bed in the cooling station and the vacuum pump exchange heat between the low-temperature gas sucked from the vacuum low-temperature adsorption station and the adsorption bed to reduce the temperature of the adsorption bed;

[0029] S5.3: The cooling station directly discharges the low-temperature gas after heat exchange.

[0030] The second aspect of the present invention is to provide a four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in power plants, the four-bed vacuum temperature swing adsorption device uses the four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants as described in any one of claims 1 to 5, and is characterized in that it includes a vacuum temperature swing adsorption mechanism and four-bed adsorption rings;

[0031] Four adsorption beds are arranged on the four-bed adsorption ring, and the four-bed adsorption ring replaces the adsorption beds inside the vacuum temperature-swing adsorption mechanism by rotating.

[0032] As a further solution of the present invention: the vacuum temperature-variable adsorption mechanism is provided with a vacuum low-temperature adsorption station, a waiting station, a heating and separation station and a cooling station, the vacuum low-temperature adsorption station, the waiting station, the heating and separation station and the cooling station are distributed in a ring shape, and the four-bed adsorption rings are matched with the vacuum low-temperature adsorption station, the waiting station, the heating and separation station and the cooling station.

[0033] As a further solution of the present invention: a driving mechanism is installed in the middle of the top surface of the vacuum temperature-variable adsorption mechanism, and the driving mechanism is used to transmit power to the four-bed adsorption rings, so that the four-bed adsorption rings rotate in the vacuum low-temperature adsorption station, waiting station, heating and separation station and cooling station.

[0034] As a further solution of the present invention: the four-bed adsorption ring includes an adsorption shell, and four isolation plates are evenly arranged inside the adsorption shell. The four isolation plates divide the inner cavity of the adsorption shell into four adsorption beds of equal volume, and a plurality of parallel adsorption inner plates are evenly arranged inside the adsorption bed.

[0035] As a further solution of the present invention: the adsorption inner plate is activated carbon, molecular sieve or metal organic framework.

[0036] Beneficial effects of the present invention:

[0037] 1. In the present invention, the four adsorption beds on the four-bed adsorption ring can be cyclically adsorbed, desorbed and regenerated. The entire adsorption process repeatedly utilizes the high temperature and low temperature states of the flue gas in the power plant, greatly reducing the processing energy consumption of CO2 separation in the flue gas of the power plant, that is, reducing the processing cost of CO2 separation in the flue gas of the power plant. It is suitable for large-scale use in the treatment of flue gas in power plants to ensure that the flue gas of the power plant meets the emission standards after treatment. The heating separation station can collect high-concentration carbon dioxide gas through a negative pressure pump, which reduces carbon emissions and obtains high-concentration carbon dioxide products, achieving the results of reducing costs and increasing efficiency.

[0038] 2. In the present invention, the a adsorption bed entering the heating and separation station will perform a heating and separation operation in the heating and separation station. Since the flue gas from the power plant is compressed and heated under the operation of the compressor, the high-temperature and high-pressure flue gas from the power plant can be used at this time. The high-temperature and high-pressure flue gas from the power plant and the a adsorption bed are exchanged with each other in the heating and separation station. On the one hand, the a adsorption bed can be heated to promote the desorption of carbon dioxide on the a adsorption bed. At the same time, the temperature of the high-temperature and high-pressure flue gas from the power plant can also be reduced, so that the high-temperature and high-pressure flue gas from the power plant enters the vacuum low-temperature adsorption station at a lower temperature, thereby ensuring the adsorption effect of the adsorption bed in the vacuum low-temperature adsorption station on carbon dioxide.

[0039] 3. In the present invention, when adsorption bed a enters the cooling station, the stability inside adsorption bed a is at a relatively high state, and there is residual carbon dioxide gas in adsorption bed a. At this time, the low-temperature gas sucked from the vacuum low-temperature adsorption station can, on the one hand, take away the residual carbon dioxide gas, and on the other hand, can also reduce the temperature of adsorption bed a, ensuring that adsorption bed a is in a relatively low temperature state when it enters the vacuum low-temperature adsorption station again, which is conducive to the re-adsorption of carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described below in conjunction with the accompanying drawings.

[0041] Figure 1 It is a flow chart of a four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant according to the present invention;

[0042] Figure 2 It is a flowchart of step 3 in the four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant according to the present invention;

[0043] Figure 3 It is a flowchart of step 5 in the four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant according to the present invention;

[0044] Figure 4 It is a flowchart of step 6 in the four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant according to the present invention;

[0045] Figure 5 It is a schematic structural diagram of a four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in a power plant according to the present invention;

[0046] Figure 6 It is a top view of a four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in a power plant according to the present invention;

[0047] Figure 7 It is a structural schematic diagram of the vacuum temperature swing adsorption mechanism of the present invention;

[0048] Figure 8 It is a schematic structural diagram of the four-bed adsorption ring in the present invention.

[0049] In the figure: 1. vacuum variable temperature adsorption mechanism; 11. vacuum low temperature adsorption station; 111. air inlet pipe; 12. waiting station; 13. heating and separation station; 131. carbon dioxide collection pipe; 14. cooling station; 15. driving mechanism; 16. rectangular trough; 2. four-bed adsorption ring; 21. adsorption shell; 22. isolation plate; 23. adsorption inner plate. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] Example 1

[0052] like Figure 1-Figure 8 As shown, the present invention discloses a four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant, comprising the following steps:

[0053] S1: Four adsorption beds are arranged on the four-bed adsorption ring 2, and the four adsorption beds can be marked as a, b, c and d in sequence. The specific adaptive adjustment is made by those skilled in the art according to the four-bed adsorption ring 2. The volumes of the four adsorption beds a, b, c and d are the same, and the four adsorption beds a, b, c and d correspond to the vacuum low-temperature adsorption station 11, the waiting station 12, the heating separation station 13 and the cooling station 14 on the vacuum temperature swing adsorption mechanism 1, respectively. It should be noted that the shape of the four-bed adsorption ring 2 is a circular ring, and the four adsorption beds a, b, c and d are equidistantly distributed on the four-bed adsorption ring 2 and occupy the same volume. The volumes of the vacuum low-temperature adsorption station 11, the waiting station 12, the heating separation station 13 and the cooling station 14 should also be the same. When the four adsorption beds a, b, c and d enter the vacuum low-temperature adsorption station 11, the waiting station 12, the heating separation station 13 and the cooling station 14 in sequence, When the adsorption beds in the vacuum temperature swing adsorption mechanism 1 are in the vacuum low-temperature adsorption station 13 and the cooling station 14, the four adsorption beds a, b, c and d will isolate the vacuum low-temperature adsorption station 11, the waiting station 12, the heating separation station 13 and the cooling station 14, so that the vacuum low-temperature adsorption station 11, the waiting station 12, the heating separation station 13 and the cooling station 14 are not connected to each other. In this way, when the adsorption beds inside the vacuum temperature swing adsorption mechanism 1 need to be replaced, it is only necessary to rotate the four-bed adsorption ring 2. For example, when the adsorption bed a completes the adsorption operation of carbon dioxide in the vacuum temperature swing adsorption mechanism 1, the four-bed adsorption ring 2 can be rotated to make the adsorption bed a leave the vacuum low-temperature adsorption station 11, and the adsorption bed d enters the vacuum low-temperature adsorption station 11 at the same time, ensuring that the vacuum low-temperature adsorption station 11 can continuously adsorb carbon dioxide in the flue gas of the power plant, thereby improving the efficiency of the vacuum temperature swing adsorption mechanism 1 in separating carbon dioxide.

[0054] The adsorption bed a on the four-bed adsorption ring 2 first enters the vacuum low-temperature adsorption station 11, and the adsorption beds b, c and d enter the waiting station 12, the heating and separation station 13 and the cooling station 14 in turn. It should be noted that since the four adsorption beds a, b, c and d on the four-bed adsorption ring 2 are integrated together, and the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14 on the vacuum temperature swing adsorption mechanism 1 correspond to the four adsorption beds on the four-bed adsorption ring 2, when the vacuum temperature swing adsorption mechanism 1 cooperates with the four-bed adsorption ring 2 to perform four-bed vacuum temperature swing adsorption on carbon dioxide in the flue gas of the power plant, it is only necessary to rotate the four-bed adsorption ring 2 to simultaneously complete the rotation of the adsorption beds in the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14 on the vacuum temperature swing adsorption mechanism 1, which greatly reduces the adsorption operation process of carbon dioxide in the flue gas of the power plant, simplifies the workload of on-site technicians, and indirectly reduces the labor cost of carbon dioxide adsorption in the flue gas of the power plant.

[0055] S2: adding power plant flue gas into the vacuum low-temperature adsorption station 11, the adsorption bed a adsorbs carbon dioxide in the power plant flue gas under vacuum low-temperature environment, when the carbon dioxide in the vacuum low-temperature adsorption station 11 reaches the saturated vapor pressure, the adsorption bed a stops adsorption. It should be noted that step S3 also includes the following steps:

[0056] S2.1: Use a compressor to pressurize the flue gas from the power plant, and transport the high-pressure flue gas from the power plant to a high-pressure pipeline. It should be noted that the working principle of the compressor is to compress the gas by mechanical means to increase the pressure of the gas. When the flue gas from the power plant is transported to the compressor through a pipeline, the compressor can compress the flue gas from the power plant into a high-pressure state. The magnitude of the pressure is adaptively selected by technical personnel in this field according to the specific flue gas from the power plant. A large amount of heat will be generated during the compression process of the flue gas from the power plant. At this time, the high-pressure pipeline can be transported to the heating and separation station 13 to transport the heat to the heating and separation station 13 to maximize the use of heat and save energy. The distribution and position of the high-pressure pipeline in the heating and separation station 13 are adaptively selected by technical personnel in this field according to the space in the heating and separation station 13 to ensure that it does not affect the rotation of the four-bed adsorption ring 2 in the heating and separation station 3;

[0057] S2.2: The flue gas from the high-voltage power plant passes through the waiting station through the high-pressure pipeline and performs heat exchange operation with the adsorption bed therein. It should be noted that after the flue gas from the high-voltage power plant is pressurized by the compressor, high-temperature flue gas will be formed in the high-pressure pipeline. The high-pressure pipeline adopts a metal pipeline that is easy to exchange heat. The high-pressure pipeline is arranged in the waiting station 12. It should be noted that it is necessary to ensure that the high-pressure pipeline in the waiting station 12 cannot affect the rotation operation of the adsorption bed in the waiting station 12. In this way, when the adsorption bed enters the waiting station 12, the high-pressure pipeline can heat the adsorption bed in the waiting station 12, and the waiting station 12 can be rotated. The adsorption bed in the station 12 is heated to above 50 degrees Celsius, which is specifically determined by technicians in this field based on the residence time of the adsorption bed in the waiting station 12, so as to reduce the energy consumption required for heating and separating the station 13. In addition, it should be noted that when the high-pressure pipeline heats the adsorption bed in the waiting station 12, the temperature of the adsorption bed increases, which will cause the carbon dioxide in the adsorption bed to desorb, thereby increasing the gas pressure in the waiting station 12, and at the same time, carbon dioxide will also be filled in the waiting station 12, which will further promote the heat exchange between the high-pressure pipeline and the waiting station 12, and improve the heat exchange effect of the high-pressure pipeline;

[0058] S2.3: The flue gas from the high-voltage power plant is automatically cooled to room temperature in the high-voltage pipeline. The high-voltage pipeline can be cooled by air or water. It should be noted that since the cooling station 14 will discharge low-temperature gas, the high-voltage pipeline can be heat exchanged with the low-temperature gas discharged from the cooling station 14 to improve the cooling efficiency of the power plant flue gas in the high-voltage pipeline.

[0059] S2.4: Use a vacuum pump to suck the low-temperature gas in the vacuum low-temperature adsorption station 11, so that the environment in the vacuum low-temperature adsorption station 11 forms a negative pressure. It should be noted that the specifications of the vacuum pump are adaptively selected by technical personnel in this field according to the vacuum degree required by the vacuum low-temperature adsorption station 11, and it is ensured that the vacuum pump can maintain or reduce the pressure in the vacuum low-temperature adsorption station 11 under rated power. The installation position of the vacuum pump is adaptively selected by technical personnel in this field according to the vacuum low-temperature adsorption station 11. It should be noted that the input pipeline of the vacuum pump is connected to the inner cavity of the vacuum low-temperature adsorption station 11. After turning on the vacuum pump, the vacuum pump can suck the low-temperature gas in the vacuum low-temperature adsorption station 11 through the input pipeline, and at the same time reduce the environmental pressure in the vacuum low-temperature adsorption station 11, so that the environmental pressure in the vacuum low-temperature adsorption station 11 is within a preset pressure range;

[0060] S2.5: The vacuum pump delivers the low-temperature gas sucked from the vacuum low-temperature adsorption station 11 to the cooling station 14, and the adsorption bed in the cooling station is pre-cooled to initially reduce the temperature of the adsorption bed. It should be noted that the output pipe of the vacuum pump is connected to the inner cavity environment of the cooling station 14, and the placement position of the output pipe in the inner cavity of the cooling station 14 is adaptively selected by technical personnel in this field according to the inner cavity environment of the cooling station 14, ensuring that it does not affect the rotation of the four-bed adsorption ring 2 in the cooling station 14;

[0061] S2.6: Use a throttle valve to transport the high-voltage power plant flue gas in the high-voltage pipeline to the vacuum low-temperature adsorption station 11. The high-voltage power plant flue gas is rapidly depressurized and absorbs heat in the vacuum low-temperature adsorption station 11, so that the environment in the vacuum low-temperature adsorption station 11 forms a low-temperature negative pressure. It should be noted that when the high-voltage flue gas flows through the throttle valve, the opening of the valve will affect the flow rate and pressure of the gas. During the throttling process, the pressure of the gas drops rapidly, causing its temperature to drop accordingly. According to the principles of thermodynamics, the gas absorbs heat during throttling, causing the temperature of the surrounding environment to drop. This process is the key to achieving pressure reduction and temperature reduction of the high-voltage power plant flue gas. Therefore, after the high-voltage power plant flue gas passes through the throttle valve and enters the vacuum low-temperature adsorption station 11, it will form a low-pressure and low-temperature power plant flue gas, that is, the environment in the vacuum low-temperature adsorption station 11 forms a low-temperature negative pressure;

[0062] S2.7: The pressure value of the environment in the vacuum low-temperature adsorption station 11 is controlled by a throttle valve. When the pressure value of the environment in the vacuum low-temperature adsorption station 11 reaches a preset pressure threshold, the introduction of high-voltage power plant flue gas into the vacuum low-temperature adsorption station 11 is stopped. It should be noted that technical personnel in this field set the pressure threshold and the low temperature range according to the vacuum low-temperature adsorption station 11. For example, the environment of the vacuum low-temperature adsorption station 11 can be -20 degrees Celsius to -10 degrees Celsius, and the pressure can be 0.05 to 0.1 atmospheres. This is just a corresponding embodiment of the vacuum low-temperature adsorption station 11. The specific environmental pressure and stable setting of the vacuum low-temperature adsorption station 11 are adaptively selected by technical personnel in this field according to the adsorption of carbon dioxide to ensure that the flue gas from the power plant meets the emission standards.

[0063] The adsorption of carbon dioxide is determined by the separation efficiency of carbon dioxide. The calculation formula for the separation efficiency of carbon dioxide in the vacuum low-temperature adsorption station 11 is:

[0064]

[0065] Where η is the separation efficiency, q m is the maximum adsorption capacity, K is the equilibrium constant, C e is the equilibrium concentration, n is the adsorption heterogeneity index, E a is the activation energy, R is the gas constant, T is the temperature in Fahrenheit, mCO2 is the mass of CO2 adsorbed, m in is the mass of the power plant flue gas entering the vacuum low-temperature adsorption station, m out is the mass of the flue gas discharged from the vacuum low-temperature adsorption station, Q is the heat, m is the mass of the adsorption zone of the four-bed adsorption ring, C p is the specific heat capacity of the adsorption zone of the four-bed adsorption ring, △T is the change in flue gas temperature of the power plant, P in is the pressure of the flue gas from the power plant before it enters the vacuum low-temperature adsorption station, P ref is the original pressure in the vacuum low-temperature adsorption station, α is the pressure coefficient, T max is the maximum adsorption temperature of the vacuum low-temperature adsorption station, β is the temperature coefficient, it should be noted that η is the separation efficiency, which indicates the total efficiency of carbon dioxide separation and reflects the performance of the system, q m is the maximum adsorption capacity, the maximum amount of carbon dioxide that the four-bed adsorption ring 2 can adsorb, indicating the effectiveness of the four-bed adsorption ring 2. K is the equilibrium constant, which describes the interaction strength between the four-bed adsorption ring 2 and carbon dioxide and affects the driving force of the adsorption process. The equilibrium constant K can be determined by the static adsorption test method, specifically:

[0066] Prepare several CO2 solutions (or gas mixtures) of known concentrations and introduce them into the four-bed adsorption ring 2; keep the system still at a preset temperature until equilibrium is reached, and then analyze the CO2 concentration on the adsorbent and the CO2 concentration in the liquid or gas phase at equilibrium. According to the Langmuir adsorption model, the equilibrium constant can be calculated using the following formula:

[0067]

[0068] where q e is the CO2 concentration on the adsorbent, C e is the equilibrium concentration, i.e., the concentration of carbon dioxide in the adsorption zone on the four-bed adsorption ring 2;

[0069] n is the adsorption heterogeneity index. It should be noted that n can be determined using a static adsorption test method, specifically:

[0070] Prepare several CO2 solutions (or gas mixtures) of known concentration and introduce them into the four-bed adsorption ring 2; keep the system at rest at a preset temperature until equilibrium is reached; record q at equilibrium e and C e ;

[0071] Fit the data to a Freundlich model:

[0072]

[0073] After linearizing the above formula, take the logarithm:

[0074]

[0075] The slope and intercept were obtained from linear regression analysis to calculate n.

[0076] The pressure coefficient α is determined by a technician in this field according to a static adsorption experiment or a dynamic adsorption experiment. The temperature coefficient β is determined by a technician in this field according to an isothermal adsorption experiment or a thermogravimetric analysis method. The pressure and temperature inside the vacuum low-temperature adsorption station 11 and the temperature of the heating separation station 13 are controlled by the separation efficiency of carbon dioxide to ensure that the separation efficiency of carbon dioxide is within a set range.

[0077] S3: Rotate the four-bed adsorption ring 2 to make the adsorption bed a enter the waiting station 12, the adsorption beds b, c and d enter the heating separation station 13, the cooling station 14 and the vacuum low-temperature adsorption station 11 in turn, and the adsorption bed d repeats step S3. It should be noted that when the adsorption bed a adsorbs carbon dioxide to saturation in the vacuum low-temperature adsorption station 11, it means that the adsorption bed a has completed the adsorption, and the four-bed adsorption ring 2 can be rotated at this time. Figure 1 and Figure 2For example, the four-bed adsorption ring 2 rotates counterclockwise, so that the adsorption bed a on the four-bed adsorption ring 2 enters the waiting station 12, and the adsorption beds b, c and d on the four-bed adsorption ring 2 enter the heating separation station 13, the cooling station 14 and the vacuum low-temperature adsorption station 11 in turn. Since the adsorption bed d was previously in the cooling station 14, the adsorption bed d must be ready to adsorb carbon dioxide. Therefore, after the adsorption bed d enters the vacuum low-temperature adsorption station 11, it can adsorb and separate carbon dioxide from the power plant flue gas in the vacuum low-temperature adsorption station 11, so that the vacuum low-temperature adsorption station 11 can continue to process the power plant flue gas, ensuring the processing efficiency of the vacuum low-temperature adsorption station 11;

[0078] S4: Rotate the four-bed adsorption ring 2 again, so that the adsorption bed a enters the heating separation station 13, and the adsorption beds b, c and d enter the cooling station 14, the vacuum low-temperature adsorption station 11 and the waiting station 12 in sequence. The adsorption bed a is heated and decompressed in the heating separation station 13 to separate the carbon dioxide from the four-bed adsorption ring 2. The adsorption bed c repeats step S3, and also includes the following steps:

[0079] S4.1: transfer the adsorption beds in the four-bed adsorption ring 2 corresponding to the waiting station 12 to the heating separation station 13;

[0080] S4.2: heating the adsorption bed in the four-bed adsorption ring 2 to 60 degrees Celsius to 100 degrees Celsius by the heating device in the heating separation station 13, so as to desorb the carbon dioxide in the adsorption bed;

[0081] S4.3: Use a vacuum pump to suck the desorbed carbon dioxide in the heating separation station 13, and pump the carbon dioxide into a gas cylinder for storage.

[0082] It should be noted that the condition for rotating the four-bed adsorption ring 2 again is that the d adsorption bed will saturate the carbon dioxide adsorption in the vacuum low-temperature adsorption station 11, so that the d adsorption bed will enter the waiting station 12, and the c adsorption bed in the cooling station 14 will enter the vacuum low-temperature adsorption station 11 to repeat the adsorption and separation operation of carbon dioxide. The a adsorption bed entering the heating separation station 13 will perform the heating and separation operation in the heating separation station 13. Since the flue gas from the power plant was compressed and heated under the operation of the compressor, the high-temperature and high-pressure power plant flue gas can be used at this time to exchange heat with the a adsorption bed in the heating separation station 13. On the one hand, the a adsorption bed can be heated to promote the desorption of carbon dioxide on the a adsorption bed, and at the same time, the temperature of the high-temperature and high-pressure power plant flue gas can be reduced, so that the high-temperature and high-pressure power plant flue gas enters the vacuum low-temperature adsorption station 11 at a lower temperature, ensuring the adsorption effect of the adsorption bed in the vacuum low-temperature adsorption station 11 on carbon dioxide;

[0083] S5: Continue to rotate the four-bed adsorption ring 2, so that the adsorption bed a enters the cooling station 14, and the adsorption beds b, c and d are successively in the vacuum low-temperature adsorption station 11, the waiting station 12 and the heating separation station 13. The adsorption bed a absorbs the remaining power plant flue gas in the cooling station 14 and exchanges heat with the vacuum low-temperature adsorption station 11, the adsorption bed b repeats step S3, and the adsorption bed d is heated and separated in the heating separation station 13, and the following steps are also included:

[0084] S5.1: transferring the adsorption beds in the corresponding four-bed adsorption ring 2 after heating and decompression in the heating and separation station 13 to the cooling station 14;

[0085] S5.2: The adsorption bed in the cooling station 14 and the vacuum pump exchange heat between the low-temperature gas sucked from the vacuum low-temperature adsorption station 11 and the adsorption bed to reduce the temperature of the adsorption bed;

[0086] S5.3: The cooling station 14 directly discharges the low-temperature gas after heat exchange;

[0087] It should be noted that when adsorption bed a enters the cooling station 14, the temperature inside adsorption bed a is at a relatively high state, and there is still residual carbon dioxide gas in adsorption bed a. At this time, the low-temperature gas sucked from the vacuum low-temperature adsorption station 11 can, on the one hand, take away the residual carbon dioxide gas, and on the other hand, can also reduce the temperature of adsorption bed a, ensuring that adsorption bed a is at a lower temperature when it enters the vacuum low-temperature adsorption station 11 again, which is conducive to the re-adsorption of carbon dioxide.

[0088] S6: Finally, rotate the four-bed adsorption ring 2, so that the adsorption bed a on the four-bed adsorption ring 2 enters the vacuum low-temperature adsorption station 11 again, and the adsorption beds b, c and d enter the waiting station 12, the heating separation station 13 and the cooling station 14 in turn. It should be noted that when the adsorption bed a on the four-bed adsorption ring 2 enters the vacuum low-temperature adsorption station 11 again, due to the low air pressure inside the vacuum low-temperature adsorption station 11, when the adsorption bed a on the four-bed adsorption ring 2 is connected to the vacuum low-temperature adsorption station 11, the pressure of the environment around the adsorption bed a will suddenly decrease, which will cause the temperature of the adsorption bed a on the four-bed adsorption ring 2 to decrease again, that is, the re-cooling operation of the adsorption bed a, so that the adsorption bed a can go through the two processes of pre-cooling and re-cooling, so the cooling of the adsorption bed a is two stages, and the temperature drops gently, which helps to protect the physical properties of the activated carbon in the adsorption bed a and ensure the re-adsorption performance of the adsorption bed a;

[0089] Repeat steps S1 to S6 until the flue gas from the power plant is completely adsorbed. Since the four adsorption beds a, b, c and d on the four-bed adsorption ring 2 correspond to the vacuum low-temperature adsorption station 11, waiting station 12, heating separation station 13 and cooling station 14 on the vacuum temperature-swing adsorption mechanism 1, the four adsorption beds a, b, c and d on the four-bed adsorption ring 2 can be cyclically adsorbed, desorbed and regenerated. The entire adsorption process reuses the high temperature and low temperature states of the flue gas from the power plant, greatly reducing the processing energy consumption of CO2 separation in the flue gas from the power plant, that is, reducing the processing cost of CO2 separation in the flue gas from the power plant, and is suitable for large-scale use in the treatment of flue gas from power plants to ensure that the flue gas from the power plant meets the emission standards after treatment. The heating separation station 13 can collect high-concentration carbon dioxide gas through a negative pressure pump, which reduces carbon emissions and obtains high-concentration carbon dioxide products, achieving the results of reducing costs and increasing efficiency.

[0090] Example 2

[0091] like Figure 1-Figure 8 As shown, the present invention discloses a four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in a power plant. The four-bed vacuum temperature swing adsorption device uses the above-mentioned four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in a power plant, and includes a vacuum temperature swing adsorption mechanism 1 and a four-bed adsorption ring 2. It should be noted that the vacuum temperature swing adsorption mechanism 1 and the four-bed adsorption ring 2 are both annular. In order to reduce the friction force of the four-bed adsorption ring 2 when rotating on the vacuum temperature swing adsorption mechanism 1, a pulley can also be installed on the bottom surface of the four-bed adsorption ring 2 to reduce the friction force of the four-bed adsorption ring 2 when rotating;

[0092] Four adsorption beds a, b, c and d are arranged on the four-bed adsorption ring 2. The four-bed adsorption ring 2 replaces the adsorption beds inside the vacuum temperature swing adsorption mechanism 1 by rotating. Since the vacuum temperature swing adsorption mechanism 1 and the four-bed adsorption ring 2 are both ring-shaped and the four adsorption beds a, b, c and d are compatible with the vacuum temperature swing adsorption mechanism 1, the four-bed adsorption ring 2 can be freely rotated on the vacuum temperature swing adsorption mechanism 1.

[0093] The vacuum temperature swing adsorption mechanism 1 is provided with a vacuum low-temperature adsorption station 11, a waiting station 12, a heating and separation station 13 and a cooling station 14. The vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14 are distributed in a ring shape, and the four-bed adsorption ring 2 matches the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14. It should be noted that the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14 occupy the same space on the vacuum temperature swing adsorption mechanism 1, so that when the adsorption bed a cooperates with the vacuum low-temperature adsorption station 11, the three adsorption beds b, c and d can just cooperate with the waiting station 12, the heating and separation station 13 and the cooling station 14.

[0094] A driving mechanism 15 is installed at the middle position of the top surface of the vacuum temperature-swing adsorption mechanism 1. The driving mechanism 15 is used to transmit power to the four-bed adsorption ring 2, so that the four-bed adsorption ring 2 rotates in the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14. It should be noted that the driving mechanism 15 includes a driving motor and a planetary reducer. The delivery shaft of the driving motor is connected to the input end of the planetary reducer, and the output end of the planetary reducer is meshed with the inner side of the four-bed adsorption ring 2 through a gear. When the driving motor is turned on, the output shaft of the driving motor can transmit power to the line through the planetary reducer. The output end of the star reducer and the output end of the planetary reducer then transmit the power to the four-bed adsorption ring 2 through gears, so as to realize the rotation of the four-bed adsorption ring 2 between the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14. The models and specifications of the drive motor and the planetary reducer are adaptively selected by technical personnel in this field according to the specifications of the vacuum variable temperature adsorption mechanism 1 and the four-bed adsorption ring 2 to ensure that the drive motor and the planetary reducer can drive the four-bed adsorption ring 2. In addition, it should be noted that the transmission between the drive motor and the planetary reducer and the four-bed adsorption ring 2 needs to be sealed.

[0095] The vacuum low temperature adsorption station 11 is connected to the cooling station 14 by a pipeline. A set of vacuum pumps can be set in the middle of the pipeline. The output end of the vacuum pump corresponds to the cooling station 14, and the input end of the vacuum pump corresponds to the vacuum low temperature adsorption station 11. Figure 1 The top surfaces of the medium vacuum low temperature adsorption station 1, the waiting station 12 and the cooling station 14 are all provided with sealing plates. Figure 1 For the sake of clarity, Figure 1 As shown in the figure, rectangular grooves 16 are provided at the joints between the vacuum low-temperature adsorption station 11, the waiting station 12, the heating and separation station 13 and the cooling station 14, and the rectangular grooves 16 are mutually matched with the four-bed adsorption ring 2. An air inlet pipe 111 is connected to one side of the vacuum low-temperature adsorption station 11, and a throttle valve is installed inside the air inlet pipe 111. The flue gas from the power plant enters the inner cavity of the vacuum low-temperature adsorption station 11 through the air inlet pipe 111. A carbon dioxide collection pipe 131 is fixedly connected to the center of the top surface of the heating and separation station 13. The carbon dioxide collection pipe 131 is connected to the gas cylinder through a negative pressure pump to ensure that the carbon dioxide gas in the carbon dioxide collection pipe 131 can be sucked into the gas cylinder by the negative pressure pump and collected. The gas cylinder can also be replaced accordingly by technical personnel in this field according to the specific conditions on site to ensure that the carbon dioxide can be collected normally.

[0096] like Figure 8As shown, the four-bed adsorption ring 2 includes an adsorption shell 21, and four isolation plates 22 are evenly arranged inside the adsorption shell 21. The four isolation plates 22 divide the inner cavity of the adsorption shell 21 into four adsorption beds of equal volume. A number of parallel adsorption inner plates 23 are evenly arranged inside the adsorption bed. It should be noted that a number of U-shaped heat exchange pipes can be distributed inside the adsorption inner plate 23, and the heat exchange pipes are used to connect the high-temperature and high-pressure power plant flue gas. The adsorption inner plate 23 can also use electric auxiliary heating to ensure that the adsorbed carbon dioxide on the adsorption inner plate 23 can be heated to 60 degrees Celsius to 100 degrees Celsius.

[0097] The adsorption inner plate 23 is activated carbon, molecular sieve or metal organic framework. It should be noted that the adsorption inner plate 23 made of activated carbon can provide good adsorption capacity for adsorbing carbon dioxide. The adsorption inner plate 23 can not only be set in a vertical state, but also can be set in a horizontal state or in a strip shape. The main purpose is to increase the contact area with the flue gas of the power plant in the vacuum low-temperature adsorption station 11 and improve the adsorption efficiency of carbon dioxide. The specifications and types of activated carbon, molecular sieve or metal organic framework are adaptively selected by technical personnel in this field according to the specific carbon dioxide adsorption situation and the composition of the flue gas of the power plant.

[0098] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants, characterized in that: The following steps are involved: S1: four adsorption beds are arranged on a four-bed adsorption ring, and the four-bed adsorption ring is rotated so that the four adsorption beds are sequentially cycled in a vacuum low-temperature adsorption station, a waiting station, a heating separation station and a cooling station on the vacuum temperature swing adsorption mechanism; S2: introducing the flue gas from the power plant into the vacuum low-temperature adsorption station, so that the adsorption bed therein generates a vacuum low-temperature environment. At the same time, when the four-bed adsorption ring rotates, the adsorption bed in the cooling station is pre-cooled; S3: The adsorption bed in the vacuum low-temperature adsorption station is transferred to the waiting station, where the adsorption bed is preheated; S4: the adsorption bed in the waiting station is transferred to the heating separation station, and the heating separation station performs heating and decompression operation on the adsorption bed therein; S5: the adsorption bed in the heating and separation station is transferred to the cooling station, and the cooling station performs a cooling operation on the adsorption bed therein; S6: Repeat S1 to S6 until the flue gas from the power plant is completely adsorbed.

2. The four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants according to claim 1 is characterized in that: The S2 comprises the following steps: S2.1: The flue gas from the power plant is pressurized by a compressor, and the high-pressure flue gas from the power plant is transported to the high-pressure pipeline. The high-pressure pipeline passes through the waiting station and performs heat exchange operation with the adsorption bed therein. The flue gas from the high-pressure power plant is automatically cooled to room temperature in the high-pressure pipeline; S2.2: The flue gas from the high-voltage power plant passes through the high-voltage pipeline and passes through the waiting station to perform heat exchange operation with the adsorption bed therein; S2.3: The high-voltage power plant flue gas after the waiting station is automatically cooled to room temperature in the high-voltage pipeline; S2.4: Use a vacuum pump to extract the low-temperature gas in the vacuum low-temperature adsorption station to form a negative pressure in the environment of the vacuum low-temperature adsorption station; S2.5: The vacuum pump transports the low-temperature gas sucked from the vacuum low-temperature adsorption station to the cooling station to pre-cool the adsorption bed in the cooling station; S2.6: Use a throttle valve to transport the high-voltage power plant flue gas in the high-voltage pipeline to the vacuum low-temperature adsorption station. The high-voltage power plant flue gas is rapidly depressurized and absorbs heat in the vacuum low-temperature adsorption station, so that the environment in the vacuum low-temperature adsorption station forms a low-temperature negative pressure; S2.7: The pressure value of the environment in the vacuum low-temperature adsorption station is controlled by a throttle valve. When the pressure value of the environment in the vacuum low-temperature adsorption station reaches a preset pressure threshold, the introduction of high-voltage power plant flue gas into the vacuum low-temperature adsorption station is stopped.

3. The four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants according to claim 2 is characterized in that: When the adsorption beds in the four-bed adsorption ring enter the vacuum low-temperature adsorption station from the cooling station, the vacuum low-temperature adsorption station reduces the pressure of the adsorption beds in the cooling station and further cools down the adsorption beds in the cooling station.

4. The four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants according to claim 1 is characterized in that: The S4 comprises the following steps: S4.1: transfer the adsorption beds in the four-bed adsorption ring corresponding to the waiting station to the heating separation station; S4.2: heating the adsorption beds in the four-bed adsorption ring to 60 degrees Celsius to 100 degrees Celsius by means of a heating device in the heating separation station, so as to desorb carbon dioxide in the adsorption beds; S4.3: Use a vacuum pump to extract the desorbed carbon dioxide in the heating separation station and pump the carbon dioxide into a gas cylinder for storage.

5. The four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants according to claim 2 is characterized in that: The S5 comprises the following steps: S5.1: transferring the adsorption beds in the corresponding four-bed adsorption ring after heating and decompression in the heating and separation station to the cooling station; S5.2: The adsorption bed in the cooling station and the vacuum pump exchange heat between the low-temperature gas sucked from the vacuum low-temperature adsorption station and the adsorption bed to reduce the temperature of the adsorption bed; S5.3: The cooling station directly discharges the low-temperature gas after heat exchange.

6. A four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in power plants, using the four-bed vacuum temperature swing adsorption process for separating CO2 from flue gas in power plants as described in any one of claims 1 to 5, characterized in that: It includes a vacuum temperature swing adsorption mechanism and a four-bed adsorption ring; The four-bed adsorption ring is provided with four adsorption beds a, b, c and d, and the four-bed adsorption ring replaces the adsorption beds inside the vacuum temperature-swing adsorption mechanism by rotating.

7. The four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in power plants according to claim 6 is characterized in that: The vacuum temperature-swing adsorption mechanism is provided with a vacuum low-temperature adsorption station, a waiting station, a heating and separation station and a cooling station. The vacuum low-temperature adsorption station, the waiting station, the heating and separation station and the cooling station are distributed in a ring shape. The four-bed adsorption ring is matched with the vacuum low-temperature adsorption station, the waiting station, the heating and separation station and the cooling station.

8. The four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in power plants according to claim 7 is characterized in that: A driving mechanism is installed at the middle position of the top surface of the vacuum temperature-swing adsorption mechanism, and the driving mechanism is used to transmit power to the four-bed adsorption rings to make the four-bed adsorption rings rotate in the vacuum low-temperature adsorption station, the waiting station, the heating and separation station and the cooling station.

9. The four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in power plants according to claim 6, characterized in that: The four-bed adsorption ring comprises an adsorption shell, four isolation plates are evenly arranged inside the adsorption shell, the four isolation plates divide the inner cavity of the adsorption shell into four adsorption beds of the same volume, and a plurality of parallel adsorption inner plates are evenly arranged inside the adsorption bed.

10. The four-bed vacuum temperature swing adsorption device for separating CO2 from flue gas in power plants according to claim 9, characterized in that: The adsorption inner plate is activated carbon, molecular sieve or metal organic framework.

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