A CO2 pressure swing and temperature swing adsorption and capture integrated device

Abstract

This invention relates to the field of adsorption technology, and in particular to an integrated CO2 pressure swing adsorption and capture device. The device includes a housing, with an air inlet unit at the bottom. The air inlet unit is connected to several pressure swing adsorption (PSA) units. The end of each PSA unit furthest from the air inlet unit is connected to several temperature swing adsorption (TSA) units via a second distribution zone. Each PSA unit is connected to one TSA unit via a heat exchange unit, and each PSA unit is connected to a desorption unit. Both the PSA and TSA units are housed within the housing, with the TSA units positioned above the PSA units. This invention first performs preliminary adsorption and capture using the PSA units, followed by secondary adsorption and capture using the TSA units, effectively improving the CO2 capture rate in flue gas and enabling the production of CO2 products of different purities suitable for different pathways, achieving integrated and efficient CO2 capture from flue gas.

Description

Technical Field

[0001] This invention relates to the field of adsorption technology, and in particular to an integrated CO2 pressure swing and temperature swing adsorption and capture device. Background Technology

[0002] CO2 is a major greenhouse gas. The concentration of CO2 in the atmosphere increased from 278 ppm in 1750 to 412 ppm in 2020, an increase of nearly 50%. It is estimated that the concentration of CO2 in the atmosphere will reach nearly 700 ppm by the end of the 21st century. my country emits nearly 10 billion tons of CO2 every year, of which industrial flue gas CO2 emissions account for 45% of the total national emissions. The need for CO2 capture is enormous.

[0003] For reducing CO2 emissions from industrial sources, adsorption capture is a promising carbon reduction technology. Depending on the process requirements, this technology utilizes the differences in adsorption performance of adsorbents for different gases to selectively adsorb them. Currently, the main applications of adsorption methods include Pressure Swing Adsorption (PSA) and Temperature Swing Adsorption (TSA). PSA is suitable for the rapid and efficient capture of high-concentration CO2 gases, while TSA is suitable for the capture of low-concentration CO2 gases. PSA achieves gas separation or purification by alternating adsorption and desorption processes through periodic pressure changes, while TSA utilizes adsorbents to perform adsorption at low temperatures and desorption at high temperatures after adsorption is complete.

[0004] While pressure swing adsorption (PSA) and temperature swing adsorption (TSA) offer numerous advantages, they also have limitations that restrict their large-scale application. PSA, due to its rapid adsorption process, suffers from a low capture rate of the adsorbate gas, with a significant amount remaining unadsorbed and lost in the exhaust gas. TSA, on the other hand, exhibits a slow adsorption rate and requires substantial energy consumption during thermal desorption, resulting in high energy costs. Therefore, combining PSA and TSA is crucial for efficient CO2 capture in industrial flue gas. This involves using PSA to capture most of the CO2 in industrial flue gas, while using TSA to capture the unadsorbed CO2 in the PSA exhaust gas, thereby improving the overall CO2 capture rate and yielding CO2 products of varying purities. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated CO2 pressure swing and temperature swing adsorption and capture device to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: an integrated CO2 pressure swing adsorption and capture device, comprising a housing, an air inlet unit disposed at the bottom of the housing, the air inlet unit being connected to a plurality of pressure swing adsorption (PSA) units, and a plurality of temperature swing adsorption (TSA) units being connected at the end of each PSA unit away from the air inlet unit via a second distribution zone; each PSA unit being connected to one TSA unit via a heat exchange unit, and each PSA unit being connected to a desorption unit; both the PSA units and the TSA units are disposed within the housing, with the TSA units positioned above the PSA units.

[0007] Preferably, the intake unit includes a first distribution area disposed within the bottom of the housing, the first distribution area being connected to the pressure swing adsorption (PSA) unit, and a compressor being connected to the first distribution area, the compressor being disposed outside the housing.

[0008] Preferably, the pressure swing adsorption (PSA) unit includes a PSA region disposed within the housing. The bottom of the PSA region is connected to the first distribution area via a plurality of first valves. The sidewall of the PSA region is connected to the desorption unit via a second valve. The heat exchange unit is connected to the PSA region via a third valve, which is disposed above the second valve. The top of the PSA region is connected to the second distribution area via a plurality of fourth valves.

[0009] Preferably, the desorption unit includes a first vacuum pump disposed outside the housing, the inlet of the first vacuum pump being connected to the second valve, and the outlet of the first vacuum pump being connected to a product gas tank.

[0010] Preferably, the heat exchange unit includes a second vacuum pump disposed outside the housing, the inlet of the second vacuum pump being connected to the third valve, the outlet of the second vacuum pump being connected to the lower part of a buffer tank, the upper part of the buffer tank being connected to a heat exchanger, and the heat exchanger being connected to the temperature-switching adsorption (TSA) unit.

[0011] Preferably, the temperature-switching adsorption (TSA) unit includes a TSA region disposed within the housing. The TSA region is connected to the second distribution area via a plurality of sixth valves. The TSA region is connected to the heat exchanger via a fifth valve, which is disposed above the third valve. A seventh valve is disposed at the top of the TSA region.

[0012] Preferably, several of the sixth valves are respectively disposed at the bottom of the TSA region and on the side wall of the TSA region away from the fifth valve.

[0013] Preferably, the cross-section of the second distribution area is inverted T-shaped.

[0014] Preferably, the PSA region and the TSA region are each filled with an adsorbent.

[0015] The present invention discloses the following technical effects:

[0016] 1. This invention combines a pressure swing adsorption (PSA) unit and a temperature swing adsorption (TSA) unit and installs them into a housing, which can effectively improve the CO2 capture rate and effectively reduce the volume and floor space of the entire device.

[0017] 2. The present invention can effectively improve the uniformity of gas distribution and the adsorption efficiency through the air intake component and the second distribution zone.

[0018] 3. This invention first uses a pressure swing adsorption (PSA) unit for initial adsorption and capture, and then uses a temperature swing adsorption (TSA) unit for secondary adsorption and capture, which effectively improves the capture rate of CO2 in industrial flue gas and can obtain CO2 product gas with different purity under different pathways, thus realizing integrated and efficient capture of CO2 in industrial flue gas. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0021] The components are as follows: 1. Housing; 2. PSA area; 3. TSA area; 4. First vacuum pump; 5. Second vacuum pump; 6. Compressor; 11. First distribution area; 12. Second distribution area; 21. First valve; 22. Second valve; 23. Third valve; 24. Fourth valve; 31. Fifth valve; 32. Sixth valve; 33. Seventh valve; 41. Product gas tank; 51. Buffer tank; 52. Heat exchanger. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1

[0025] Reference Figure 1 This invention provides an integrated CO2 pressure swing adsorption and capture device, comprising a housing 1, an air inlet unit at the bottom of the housing 1, the air inlet unit being connected to a plurality of pressure swing adsorption (PSA) units, and a plurality of temperature swing adsorption (TSA) units at the end of the PSA units away from the air inlet unit being connected to a plurality of temperature swing adsorption (TSA) units through a second distribution zone 12, each PSA unit being connected to a TSA unit through a heat exchange unit, and each PSA unit being connected to a desorption unit; both the PSA units and the TSA units are disposed within the housing 1, with the TSA units positioned above the PSA units.

[0026] This invention combines a pressure swing adsorption (PSA) unit and a temperature swing adsorption (TSA) unit and installs them into the housing 1, which can effectively improve the CO2 capture rate and effectively reduce the volume and floor space of the entire device.

[0027] The present invention, through the air intake component and the second distribution zone 12, can effectively improve the uniformity of gas distribution and effectively improve the adsorption efficiency.

[0028] This invention first uses a pressure swing adsorption (PSA) unit for initial adsorption and capture, and then uses a temperature swing adsorption (TSA) unit for secondary adsorption and capture, which effectively improves the capture rate of CO2 in industrial flue gas and can obtain CO2 product gas with different purity and applicable to different pathways, thus realizing integrated and efficient capture of CO2 in industrial flue gas.

[0029] This invention first performs partial desorption using a pressure swing adsorption (PSA) unit, and the low-concentration desorbed gas is used for purging during desorption in a temperature swing adsorption (TSA) unit to obtain CO2 product gas. Furthermore, by combining the PSA unit and the TSA unit, the process of existing CO2 adsorption and capture technology can be simplified.

[0030] Further optimization of the scheme: the air intake unit includes a first distribution area 11 disposed inside the bottom of the housing 1. The first distribution area 11 is connected to the pressure swing adsorption (PSA) unit. The first distribution area 11 is connected to a compressor 6, which is disposed outside the housing 1.

[0031] Further optimization of the scheme: The pressure swing adsorption (PSA) unit includes a PSA region 2 disposed within the housing 1. The bottom of the PSA region 2 is connected to the first distribution area 11 through several first valves 21. The sidewall of the PSA region 2 is connected to the desorption unit through a second valve 22. The heat exchange unit is connected to the PSA region 2 through a third valve 23, which is disposed above the second valve 22. The top of the PSA region 2 is connected to the second distribution area 12 through several fourth valves 24.

[0032] Further optimization of the scheme: the desorption unit includes a first vacuum pump 4 installed outside the housing 1. The inlet end of the first vacuum pump 4 is connected to the second valve 22, and the outlet end of the first vacuum pump 4 is connected to the product gas tank 41.

[0033] Further optimization of the scheme: the heat exchange unit includes a second vacuum pump 5 installed outside the housing 1. The inlet end of the second vacuum pump 5 is connected to the third valve 23. The outlet end of the second vacuum pump 5 is connected to the lower part of the buffer tank 51. The upper part of the buffer tank 51 is connected to the heat exchanger 52. The heat exchanger 52 is connected to the temperature-switching adsorption TSA unit.

[0034] Further optimization of the scheme: the temperature-switching adsorption TSA unit includes a TSA region 3 set in the housing 1. The TSA region 3 is connected to the second distribution area 12 through several sixth valves 32. The TSA region 3 is connected to the heat exchanger 52 through a fifth valve 31. The fifth valve 31 is set above the third valve 23. A seventh valve 33 is set on the top of the TSA region 3.

[0035] To further optimize the scheme, several sixth valves 32 are respectively set at the bottom of TSA area 3 and on the side wall of TSA area 3 away from the fifth valve 31.

[0036] Further optimization of the scheme resulted in the cross-section of the second distribution area 12 being inverted T-shaped.

[0037] The scheme was further optimized by filling PSA region 2 and TSA region 3 with adsorbent.

[0038] The adsorbent in PSA region 2 includes any one or a combination of at least two of activated carbon, molecular sieves, silica gel, or alumina.

[0039] The adsorbents in TSA region 3 include solid amine adsorbents, ion exchange modified adsorbents, and other CO2 capture-specific adsorbents.

[0040] Work process:

[0041] After pretreatment processes such as impurity removal and cooling, the industrial flue gas is compressed and pressurized by compressor 6 and then introduced into the first distribution zone 11 of the shell 1. Opening the first valve 21 allows the gas to distribute into the PSA region 2 for CO2 pressure swing adsorption. Simultaneously, the fourth valve 24 is opened, allowing unadsorbed adsorption tail gas to enter the second distribution zone 12. After adsorption is complete, the first valve 21 and the fourth valve 24 are closed, and vacuum desorption is performed. First, the third valve 23 is opened, and the second vacuum pump 5 is activated. The second vacuum pump 5 performs desorption, obtaining the first desorbed gas, which is stored in the buffer tank 51. After this desorption process takes a certain period, the third valve 23 is closed, and the second valve 22 is opened for vacuum desorption, obtaining the second desorbed gas, i.e., the... A product gas is stored in product gas tank 41. By opening the sixth valve 32, the adsorption tail gas in the second distribution zone 12 enters the TSA zone 3 to facilitate adsorption exchange. Temperature-switched adsorption occurs in the TSA zone 3, capturing unadsorbed CO2 from the adsorption tail gas in the second distribution zone 12. The fifth valve 31 is opened to release the second desorption gas from the buffer tank 51. The second desorption gas flows through the heat exchanger 52, which is connected to the factory's waste heat network, allowing heat exchange between the second desorption gas and the factory's waste heat. The heated second desorption gas is then passed into the adsorbent in the TSA zone 3 for thermal purging desorption. The seventh valve 33 is opened to desorb the third desorption gas, which is the second product gas containing CO2. Both PSA zone 2 and TSA zone 3 contain several independent adsorption units, ensuring the continuous operation of the PSA and TSA adsorption processes.

[0042] The parameters for pressure adsorption are: pressure 150-500 kPa (absolute pressure), time 1-10 min; the parameters for vacuum desorption are: pressure 10-50 kPa, time 1-10 min. In this process, pressure swing adsorption desorption first occurs in the lower part of the airflow direction. After a certain period of desorption in the lower part of the airflow direction, vacuum desorption occurs in the upper part of the airflow direction. The lower part of the airflow direction is preferentially desorbed for 0.1-3 min. After this time, the upper and lower parts of the adsorption region desorb together and the desorption process ends simultaneously.

[0043] Temperature-switched adsorption processes all include three stages: adsorption, heat exchange, and desorption. The adsorption temperature in the adsorption stage is 10-40℃, and the desorption temperature in the desorption stage is 50-200℃.

[0044] The purge gas for temperature swing adsorption-desorption comes from the pressure swing adsorption (PSA) unit. The desorption gas from the PSA unit is first stored in the buffer tank 51 and then released from the buffer tank 51 for the desorption of the adsorbent in different TSA zones 3. The heat required for desorption comes from the low-grade waste heat of the plant.

[0045] This invention involves capturing CO2 from industrial flue gas through pressure swing adsorption (PSA) and temperature swing adsorption (TSA). By capturing CO2 in the industrial flue gas twice and desorbing the adsorbent after PSA in stages and at different times, two desorbed gases of different concentrations are obtained by utilizing the desorption characteristics of PSA. The low-concentration desorbed gas from PSA and the waste heat from the factory are used to desorb the adsorbent in the TSA phase, resulting in the product gas. The entire capture process can achieve highly efficient CO2 capture.

[0046] Example 2

[0047] Similar to Example 1, this example uses blast furnace gas from iron and steel as the raw material gas for CO2 capture. The composition of the raw material gas is shown in Table 1. The adsorbent used in pressure swing adsorption is a molecular sieve, and the adsorbent used in temperature swing adsorption is a solid amine.

[0048] Table 1

[0049]

[0050] The blast furnace gas feedstock gas volume is 1000 Nm³. 3 / h, after pretreatment processes such as impurity removal and cooling, industrial flue gas is introduced into the shell 1. The first valve 21 is opened, and the gas is distributed into the PSA region 2 for CO2 pressure swing adsorption. Each PSA region 2 is filled with molecular sieves, with a molecular sieve loading of 1500 kg. The adsorption pressure is 500 kPa, the adsorption temperature is 10℃, and the adsorption time is 10 min. At the same time, the fourth valve 24 is opened, and the unadsorbed adsorption tail gas enters the second distribution zone 12. After adsorption is completed, the first valve 21 and the fourth valve 24 are closed for vacuum desorption. The vacuum desorption pressure is 10 kPa. First, the third valve 23 is opened, and the second vacuum pump 5 is turned on for desorption to obtain the first desorbed gas, which is stored in the buffer tank 51. This part of the desorption time is 0.5 min. Then, the third valve 23 is closed, and the second valve 22 is opened for vacuum desorption. This part of the desorption time is 9.5 min, to obtain the second desorbed gas, which is the first product gas, and is stored in the product gas tank 41.

[0051] After the adsorption tail gas of the pressure swing adsorption (PSA) unit enters the second distribution zone 12, the sixth valve 32 is opened for temperature swing adsorption. Each TSA zone 3 is filled with solid amine adsorbent, with a loading amount of 5000 kg and an adsorption temperature of 30°C.

[0052] After the TSA region 3, which has completed temperature-switching adsorption, is heated for desorption, the sixth valve 32 is closed and the fifth valve 31 is opened. The first desorption gas in the buffer tank 51 is heated by the heat exchanger and then introduced into the TSA region 3 for hot purge desorption. The desorption temperature is 90℃. The third desorption gas is obtained, which is the second product gas of CO2.

[0053] The composition of the product gas obtained in this embodiment is shown in Table 2:

[0054] Table 2

[0055]

[0056] Using the CO2 pressure swing and temperature swing adsorption-capture integrated device of this embodiment, the purity of the first product gas of CO2 was 95.1%, the purity of the second product gas was 75.2%, and the overall CO2 capture rate was 96.1%.

[0057] Example 3

[0058] Similar to Example 2, except that CO2 is only captured by pressure swing adsorption and not by temperature swing adsorption of the tail gas. The specific steps include:

[0059] The blast furnace gas feedstock gas volume is 1000 Nm³. 3 After impurity removal and cooling, the gas enters the pressure swing adsorption zone (each PSA zone 2 is filled with molecular sieves, with a molecular sieve loading of 1500 kg). The adsorption pressure is 500 kPa (absolute pressure), the adsorption temperature is 10℃, the adsorption time is 10 min, the vacuum desorption pressure is 10 kPa (absolute pressure), and the total vacuum desorption time is 10 min, resulting in the product gas.

[0060] The composition of the product gas obtained in this embodiment is shown in Table 3:

[0061] Table 3

[0062]

[0063] In this embodiment, the purity of the CO2 product gas was 65.1%, and the overall CO2 capture rate was 70.2%, which was 25.9% lower than that of Example 2.

[0064] Example 4

[0065] Similar to Example 2, the difference is that in the vacuum desorption stage after pressure swing adsorption is completed, only the second valve 22 is opened for desorption, and the third valve 23 is not opened for the initial vacuum desorption. In the temperature swing adsorption desorption stage, pressure swing adsorption desorption gas is not used for purging, and electric heating is used to heat the adsorption tower. Specifically, the following steps are included:

[0066] The blast furnace gas feedstock gas volume is 1000 Nm³. 3 / h, after pretreatment processes such as impurity removal and cooling, the industrial flue gas is introduced into the shell 1. The first valve 21 is opened, and the gas is distributed into the PSA region 2 for CO2 pressure swing adsorption. Each PSA region 2 is filled with molecular sieves, with a molecular sieve loading of 1500 kg. The adsorption pressure is 500 kPa (absolute pressure), the adsorption temperature is 10℃, and the adsorption time is 10 min. At the same time, the fourth valve 24 is opened, and the unadsorbed adsorption tail gas enters the second distribution zone 12. After adsorption is completed, the first valve 21 and the fourth valve 24 are closed for vacuum desorption. The vacuum desorption pressure is 10 kPa (absolute pressure), and the second valve 22 is opened for vacuum desorption. This part of the desorption takes 10 min to obtain the second desorbed gas, which is the first product gas, and is stored in the product gas tank.

[0067] After the adsorption tail gas of the pressure swing adsorption (PSA) unit enters the second distribution zone 12, the sixth valve 32 is opened for temperature swing adsorption. Each TSA zone 3 is filled with solid amine adsorbent, with a loading amount of 5000 kg and an adsorption temperature of 30°C.

[0068] After completing the temperature-switching adsorption, the TSA region 3 is heated for desorption. The sixth valve 32 is closed and the seventh valve 33 is opened. The desorption temperature is 90℃, and the third desorbed gas is obtained, which is the second product gas of CO2.

[0069] The product gas composition obtained in this embodiment is shown in Table 4.

[0070] Table 4

[0071]

[0072] In this comparative example, the purity of the first product gas of CO2 was 65.1%, the purity of the second product gas was 57.2%, and the overall CO2 capture rate was 80.3%, which was 15.8% lower than that of Example 2.

[0073] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0074] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A CO2 pressure swing and temperature swing adsorption-capture integrated device, characterized in that: The device includes a housing (1), with an air intake unit at the bottom of the housing (1). The air intake unit is connected to several pressure swing adsorption (PSA) units. The end of each PSA unit away from the air intake unit is connected to several temperature swing adsorption (TSA) units through a second distribution area (12). Each PSA unit is connected to a TSA unit through a heat exchange unit. Each PSA unit is connected to a desorption unit. Both the PSA units and the TSA units are located inside the housing (1), and the TSA units are located above the PSA units. The air intake unit includes a first distribution area (11) disposed in the bottom of the housing (1); The pressure swing adsorption (PSA) unit includes a PSA region (2) disposed within the housing (1). The bottom of the PSA region (2) is connected to the first distribution area (11) via a plurality of first valves (21). The sidewall of the PSA region (2) is connected to the desorption unit via a second valve (22). The heat exchange unit is connected to the PSA region (2) via a third valve (23). The third valve (23) is disposed above the second valve (22). The top of the PSA region (2) is connected to the second distribution area (12) via a plurality of fourth valves (24). The heat exchange unit includes a second vacuum pump (5) disposed outside the housing (1). The inlet of the second vacuum pump (5) is connected to the third valve (23). The outlet of the second vacuum pump (5) is connected to the lower part of the buffer tank (51). The upper part of the buffer tank (51) is connected to the heat exchanger (52). The heat exchanger (52) is connected to the temperature-switching adsorption TSA unit. The temperature-switching adsorption (TSA) unit includes a TSA region (3) disposed within the housing (1). The TSA region (3) is connected to the second distribution area (12) through a plurality of sixth valves (32). The TSA region (3) is connected to the heat exchanger (52) through a fifth valve (31). The fifth valve (31) is disposed above the third valve (23). A seventh valve (33) is disposed on the top of the TSA region (3). The cross-section of the second distribution area (12) is inverted T-shaped.

2. The integrated CO2 pressure swing and temperature swing adsorption and capture device according to claim 1, characterized in that: The first distribution area (11) is connected to the pressure swing adsorption (PSA) unit, and the first distribution area (11) is connected to a compressor (6), which is located outside the housing (1).

3. The integrated CO2 pressure swing and temperature swing adsorption and capture device according to claim 1, characterized in that: The desorption unit includes a first vacuum pump (4) disposed outside the housing (1). The inlet end of the first vacuum pump (4) is connected to the second valve (22), and the outlet end of the first vacuum pump (4) is connected to the product gas tank (41).

4. The integrated CO2 pressure swing and temperature swing adsorption and capture device according to claim 1, characterized in that: Several of the sixth valves (32) are respectively disposed at the bottom of the TSA region (3) and on the side wall of the TSA region (3) away from the fifth valve (31).

5. The integrated CO2 pressure swing and temperature swing adsorption and capture device according to claim 1, characterized in that: The PSA region (2) and TSA region (3) are respectively filled with adsorbent.

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