Carbon dioxide absorbent pregnant solution double-tower cascade catalytic desorption system and method

Abstract

The invention relates to the field of carbon dioxide capture, and provides a carbon dioxide absorbent pregnant solution double-tower cascade catalytic desorption system and method. The carbon dioxide absorbent rich liquor double-tower cascade catalytic desorption system comprises a low-temperature catalytic desorption tower, a solid acid catalyst packing layer is arranged in the low-temperature catalytic desorption tower, and an absorbent liquid outlet is formed in the tower bottom of the low-temperature catalytic desorption tower; the high-temperature thermal desorption tower is connected with the low-temperature catalytic desorption tower in series, a common filler layer without catalytic action is arranged in the high-temperature thermal desorption tower, and an absorbent liquid inlet is formed in the top of the high-temperature thermal desorption tower; an absorbent liquid outlet of the low-temperature catalytic desorption tower is communicated with an absorbent liquid inlet of the high-temperature thermal desorption tower through a pipeline, and the low-temperature catalytic desorption tower is used for conveying the absorbent subjected to low-temperature catalytic desorption to the high-temperature thermal desorption tower for high-temperature thermal desorption. According to the carbon dioxide absorbent pregnant solution double-tower cascade catalytic desorption system, the desorption temperature can be reduced, and the cyclic loading capacity of the absorbent can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon dioxide capture, and provides a carbon dioxide absorbent rich solution double-column cascade catalytic desorption system and method. BACKGROUND

[0002] In carbon capture, utilization and storage technology, chemical absorption is one of the most commonly used flue gas carbon capture methods, and liquid organic amine absorbents are favored due to their excellent performance.

[0003] In the prior art, a common absorbent regeneration method is to perform thermal desorption through a single desorption column. Although this method can improve the desorption efficiency, it requires a high desorption temperature, resulting in a significant increase in energy consumption, which seriously hinders the widespread application of carbon capture technology. The existing absorbent regeneration systems have the common feature that a single desorption column is used, and catalyst layers and packing layers are alternately arranged in the column to achieve catalytic desorption. However, these systems only reduce the desorption temperature through catalysts and do not change the equilibrium state of the desorption process. The equilibrium state is closely related to the desorption temperature, and reducing the desorption temperature reduces the circulation load of the absorbent. Therefore, the increase in the amount of absorbent used and the circulation amount actually does not effectively reduce the regeneration energy consumption, but rather increases the energy consumption. SUMMARY

[0004] The embodiment of the present application provides a carbon dioxide absorbent rich solution double-column cascade catalytic desorption system, which can reduce the desorption temperature and ensure the circulation load of the absorbent.

[0005] The embodiment of the present application also provides a carbon dioxide absorbent rich solution double-column cascade catalytic desorption method.

[0006] The first aspect of the embodiment of the present application provides a carbon dioxide absorbent rich solution double-column cascade catalytic desorption system, comprising: a low-temperature catalytic desorption column, a solid acid catalyst packing layer is arranged in the low-temperature catalytic desorption column, and an absorbent liquid outlet is arranged at the bottom of the low-temperature catalytic desorption column; a high-temperature thermal desorption column, which is arranged in series with the low-temperature catalytic desorption column, a common packing layer without catalytic action is arranged in the high-temperature thermal desorption column, and an absorbent liquid inlet is arranged at the top of the high-temperature thermal desorption column; The absorbent liquid outlet of the low-temperature catalytic desorption column is communicated with the absorbent liquid inlet of the high-temperature thermal desorption column through a pipeline, and is used to transport the absorbent after low-temperature catalytic desorption to the high-temperature thermal desorption column for high-temperature thermal desorption.

[0007] According to one embodiment of the present application, the low-temperature catalytic desorption tower and the high-temperature thermal desorption tower each sequentially comprise, from bottom to top, a tower bottom storage tank, a packed desorption section, and a water-cooled purification section; the solid acid catalyst packing layer is located in the packed desorption section of the low-temperature catalytic desorption tower, and the ordinary packing layer is located in the packed desorption section of the high-temperature thermal desorption tower.

[0008] According to one embodiment of the present application, the system further comprises a first reboiler and a second reboiler; The first reboiler is connected to the tower bottom storage tank of the low-temperature catalytic desorption tower and is used to heat the absorbent in the low-temperature catalytic desorption tower, maintaining the tower temperature of the low-temperature catalytic desorption tower at 80-95 degrees Celsius; The second reboiler is connected to the tower bottom storage tank of the high-temperature thermal desorption tower and is used to heat the absorbent in the high-temperature thermal desorption tower, maintaining the tower temperature of the high-temperature thermal desorption tower at 95-110 degrees Celsius.

[0009] According to one embodiment of the present application, the solid acid catalyst packing layer in the low-temperature catalytic desorption tower is composed of a solid acid desorption catalyst and an inert component mixed in a preset ratio.

[0010] According to one embodiment of the present application, the top of the low-temperature catalytic desorption tower and the top of the high-temperature thermal desorption tower are each provided with a liquid distribution device, which is connected to the absorbent liquid inlet of the respective tower top and is used to uniformly spray the absorbent to the solid acid catalyst packing layer or the ordinary packing layer.

[0011] According to one embodiment of the present application, the system further comprises a first delivery pump and a second delivery pump; The outlet of the first delivery pump is connected to the absorbent liquid inlet of the top of the low-temperature catalytic desorption tower and is used to pump the saturated absorbent; The second delivery pump is arranged on a pipeline connecting the absorbent liquid outlet of the low-temperature catalytic desorption tower and the absorbent liquid inlet of the high-temperature thermal desorption tower and is used to deliver the absorbent after low-temperature catalytic desorption.

[0012] According to one embodiment of the present application, the low-temperature catalytic desorption tower and the high-temperature thermal desorption tower are each provided with a gas outlet and a temperature measuring point and a pressure measuring point for monitoring the tower temperature and the tower pressure.

[0013] The second aspect embodiment of the present application provides a method for desorbing a carbon dioxide absorbent rich solution by using the above-mentioned carbon dioxide absorbent rich solution two-tower gradient catalytic desorption system, comprising: The saturated absorbent absorbing carbon dioxide is delivered to the low-temperature catalytic desorption tower, a first desorption temperature is controlled in the low-temperature catalytic desorption tower, the saturated absorbent flows through the solid acid catalyst packing layer for catalytic desorption, and a semi-lean liquid absorbent is obtained; The obtained semi-lean liquid absorbent is transported to the high-temperature thermal desorption tower, and a second desorption temperature is controlled in the high-temperature thermal desorption tower, so that the semi-lean liquid absorbent flows through the general packing layer to be thermally desorbed, and a lean liquid absorbent is obtained. The second desorption temperature is higher than the first desorption temperature.

[0014] According to an embodiment of the present application, the first preset temperature is 80-95 degrees Celsius.

[0015] According to an embodiment of the present application, the second preset temperature is 95-110 degrees Celsius.

[0016] The two-tower gradient catalytic desorption system for carbon dioxide absorbent rich liquid provided by the embodiment of the first aspect of the present application has a gradient desorption mode in which the two towers are connected in series, thereby avoiding the high energy consumption problem of the traditional single-tower full-temperature thermal desorption. The low-temperature catalytic desorption tower uses the catalytic effect of the solid acid catalyst to realize the rapid desorption of part of the carbon dioxide in the absorbent at a lower temperature without consuming a large amount of heat energy. The high-temperature thermal desorption tower only needs to perform deep treatment on the absorbent that has been preliminarily desorbed, and the load is significantly reduced, so that the overall energy consumption is greatly reduced compared with the traditional single-tower process, thereby solving the industry pain point that the energy consumption of single-tower thermal desorption is high. The solid acid catalyst packing layer can reduce the activation energy of the absorbent desorption reaction, accelerate the carbon dioxide desorption rate, shorten the preliminary desorption time, and improve the processing capacity per unit time. The general packing layer of the high-temperature thermal desorption tower enhances the mass transfer effect, so that the absorbent fully contacts heat at a high temperature, deeply releases the remaining carbon dioxide, and ensures that the desorption rate reaches the balance limit. The synergistic effect of the two ensures the desorption speed and the desorption depth, thereby avoiding the defects that the single catalytic desorption has a high speed but is not complete, or the single high-temperature thermal desorption is complete but has a high energy consumption. The low-temperature catalytic desorption stage releases a large amount of carbon dioxide in advance, reduces the carbon dioxide load of the absorbent in the high-temperature thermal desorption stage, so that the high-temperature stage can realize deep desorption without excessively increasing the temperature, thereby avoiding the problem that the absorbent is degraded or the circulation load is reduced due to high temperature. At the same time, the high-temperature thermal desorption of the general packing layer can break through the balance limit of the catalytic desorption, ensure that the residual amount of carbon dioxide in the lean liquid absorbent is very low, and ensure the adsorption capacity of the absorbent during circulation, thereby solving the technical bottleneck that the circulation load is reduced in the single catalytic desorption.

[0017] The second desorption temperature is higher than the first desorption temperature, which can break the desorption equilibrium state of carbon dioxide and the absorbent, deeply decarbonize the semi-lean liquid absorbent, greatly improve the overall desorption rate, and reduce the residual amount of carbon dioxide in the lean liquid absorbent to the minimum. The ordinary filler layer enhances the turbulent effect of the absorbent, expands the heat and mass transfer area, fully exchanges heat between the absorbent and the high-temperature environment, ensures efficient desorption of the remaining carbon dioxide, and avoids incomplete desorption due to insufficient heat transfer. High-temperature thermal desorption is only for semi-lean liquid absorbent that has removed a large amount of carbon dioxide. Compared with the traditional single tower high-temperature heating of saturated absorbent, the load is significantly reduced, further reducing energy waste. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0019] Figure 1 is a schematic structural diagram of the two-tower gradient catalytic desorption system of the carbon dioxide absorbent rich liquid provided by the present application.

[0020] Figure 2 is a schematic flow chart of the two-tower gradient catalytic desorption method of the carbon dioxide absorbent rich liquid provided by the present application.

[0021] Reference signs: 100, low-temperature catalytic desorption tower; 102, high-temperature thermal desorption tower; 104, absorbent liquid outlet; 106, absorbent liquid inlet; 108, first reboiler; 110, second reboiler; 112, liquid distribution device; 114, first delivery pump; 116, second delivery pump; 118, gas outlet. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be further described in detail below in combination with the drawings and examples. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0023] As Figure 1 shown in the first aspect of the present application, a two-tower gradient catalytic desorption system for carbon dioxide absorbent rich solution is provided, comprising: a low-temperature catalytic desorption tower 100, a solid acid catalyst packing layer is arranged in the low-temperature catalytic desorption tower 100, and an absorbent liquid outlet 104 is arranged at the bottom of the low-temperature catalytic desorption tower 100; a high-temperature thermal desorption tower 102, which is arranged in series with the low-temperature catalytic desorption tower 100, a common packing layer without catalytic effect is arranged in the high-temperature thermal desorption tower 102, and an absorbent liquid inlet 106 is arranged at the top of the high-temperature thermal desorption tower 102; Wherein, the absorbent liquid outlet 104 of the low-temperature catalytic desorption tower 100 is communicated with the absorbent liquid inlet 106 of the high-temperature thermal desorption tower 102 through a pipeline, for conveying the absorbent after low-temperature catalytic desorption to the high-temperature thermal desorption tower 102 for high-temperature thermal desorption.

[0024] According to the two-tower gradient catalytic desorption system for carbon dioxide absorbent rich solution provided by the first aspect of the present application, the gradient desorption mode of the two towers in series avoids the high energy consumption problem of the traditional single-tower high-temperature thermal desorption. The low-temperature catalytic desorption tower 100 utilizes the catalytic effect of the solid acid catalyst to realize the rapid desorption of part of the carbon dioxide in the absorbent at a lower temperature without consuming a large amount of heat energy; the high-temperature thermal desorption tower 102 only needs to perform deep treatment on the absorbent after preliminary desorption, the load is significantly reduced, the overall energy consumption is greatly reduced compared with the traditional single-tower process, and the industry pain point of high energy consumption of single-tower thermal desorption is solved. The solid acid catalyst packing layer can reduce the activation energy of the absorbent desorption reaction, accelerate the carbon dioxide desorption rate, shorten the preliminary desorption time, and improve the processing capacity per unit time; the common packing layer of the high-temperature thermal desorption tower 102 enhances the mass transfer effect, so that the absorbent fully contacts heat in a high-temperature environment, deeply releases the remaining carbon dioxide, and ensures that the desorption rate reaches the balance limit. The synergistic effect of the two ensures the desorption speed and the desorption depth, avoiding the defects of single catalytic desorption with fast speed but incomplete desorption or single high-temperature thermal desorption with completeness but high energy consumption. The low-temperature catalytic desorption stage releases a large amount of carbon dioxide in advance, reduces the carbon dioxide load of the absorbent in the high-temperature thermal desorption stage, so that the high-temperature stage can realize deep desorption without excessively increasing the temperature, avoiding the problem of absorbent degradation or reduced circulation load caused by high temperature. At the same time, the high-temperature thermal desorption of the common packing layer can break through the balance limit of catalytic desorption, ensure that the residual amount of carbon dioxide in the lean liquid absorbent is extremely low, and protect the adsorption capacity of the absorbent during circulation use, solving the technical bottleneck of reduced circulation load of single catalytic desorption.

[0025] Please continue to see Figure 1The low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102 are arranged in series through pipelines, the pipelines are designed to be heat-preserved, and temperature loss of the absorbent in the conveying process is reduced.

[0026] The low-temperature catalytic desorption tower 100 is a vertical closed tower body made of corrosion-resistant materials to ensure the chemical properties of the absorbent. A solid acid catalyst packing layer is fixedly arranged in the middle region of the tower body, the packing layer is uniformly filled to form a continuous catalytic reaction region, and sufficient contact area is provided for the absorbent. An absorbent liquid outlet 104 is arranged at the bottom of the tower body, and a sealing valve is arranged at the outlet to ensure stable pressure in the tower body and facilitate control of the discharge rate of the absorbent. The absorbent enters from the top of the tower body, flows through the solid acid catalyst packing layer from top to bottom, and is discharged from the liquid outlet at the bottom after preliminary desorption under the catalytic action.

[0027] The high-temperature thermal desorption tower 102 is also a vertical closed tower body, which is structurally matched with the low-temperature catalytic desorption tower 100 and made of materials with high-temperature resistance and corrosion resistance. A normal packing layer is arranged in the middle region of the tower body, the packing layer has no catalytic effect and is mainly used to enhance the mass transfer effect of the absorbent in the high-temperature environment, and the packing is regularly arranged to ensure smooth flow of the absorbent. An absorbent liquid inlet 106 is arranged at the top end of the tower body, and the inlet pipeline is in sealed communication with the absorbent liquid outlet 104 pipeline of the low-temperature catalytic desorption tower 100 to form a leak-free conveying channel. The absorbent enters from the top inlet of the tower body, flows through the normal packing layer to complete deep desorption, and is stored at the bottom or discharged from the bottom outlet.

[0028] The low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102 are arranged in series through pipelines, the pipelines are designed to be heat-preserved, and temperature loss of the absorbent in the conveying process is reduced. The flow path of the absorbent is as follows: the carbon dioxide absorbent rich liquid to be desorbed first enters the low-temperature catalytic desorption tower 100, flows through the solid acid catalyst packing layer for catalytic desorption; the absorbent after preliminary desorption enters the connecting pipeline through the liquid outlet at the bottom, and is conveyed to the liquid inlet at the top of the high-temperature thermal desorption tower 102; after entering the high-temperature thermal desorption tower 102, the absorbent flows through the normal packing layer for high-temperature thermal desorption, and finally completes the whole-process cascade desorption.

[0029] The catalytic characteristics of the solid acid catalyst packing layer and the mass transfer characteristics of the normal packing layer are complementary, the low-temperature catalytic desorption tower 100 focuses on rapid start of the desorption reaction at a lower temperature, and the high-temperature thermal desorption tower 102 focuses on deep decarburization at a higher temperature. The series connection of the two towers ensures that the absorbent is first pretreated by catalysis and then strengthened by high temperature, forming a cascade desorption logic of first catalytic acceleration and then high-temperature efficiency improvement, which ensures the desorption efficiency and controls the energy consumption.

[0030] According to one embodiment of the present application, the low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102 each sequentially include, from bottom to top, a tower bottom storage tank, a packed desorption section, and a water-cooled purification section; the solid acid catalyst packing layer is located in the packed desorption section of the low-temperature catalytic desorption tower 100, and the ordinary packing layer is located in the packed desorption section of the high-temperature thermal desorption tower 102.

[0031] In one embodiment of the present application, the internal structures of the low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102 are completely consistent, and each sequentially includes, from bottom to top, a tower bottom storage tank, a packed desorption section, and a water-cooled purification section. The tower bottom storage tank is located at the lowermost end of the tower body and has a closed cavity structure, and is used to store the absorbent in the tower to ensure that the absorbent has sufficient residence time to complete desorption. The packed desorption section is located above the tower bottom storage tank, the packed desorption section of the low-temperature catalytic desorption tower 100 is filled with a solid acid catalyst packing layer, and the packed desorption section of the high-temperature thermal desorption tower 102 is filled with an ordinary packing layer. The packing layers are arranged in a regular arrangement to ensure that the absorbent can uniformly flow through the surface of the packing. The water-cooled purification section is located at the uppermost end of the tower body, and is provided with a spraying device and a condensing pipeline inside. The spraying device sprays purification water, and the condensing pipeline is connected to cooling water, which is used to cool and purify the gas generated by desorption to remove the absorbent mist in the gas.

[0032] The provision of the tower bottom storage tank provides a stable residence space for the absorbent, ensures that the desorption reaction proceeds fully, and avoids the absorbent flowing too quickly through the tower body, which can result in incomplete desorption. The regular arrangement of the packing in the packed desorption section maximizes the contact area between the absorbent and the packing, improves the mass transfer efficiency, accelerates the desorption reaction rate, and the solid acid catalyst packing layer of the low-temperature catalytic desorption tower 100 and the ordinary packing layer of the high-temperature thermal desorption tower 102 are respectively adapted to the requirements of the corresponding desorption stage to ensure the optimal desorption efficiency of each stage. The water-cooled purification section can effectively cool the desorption gas, recover the absorbent mist entrained in the gas, reduce the loss of the absorbent, purify the carbon dioxide gas, and improve the gas purity, which makes subsequent processing more convenient. The three-section internal structure makes the tower body function clear, and the desorption, storage, and purification are integrated, which simplifies the system structure and reduces the equipment investment cost.

[0033] According to one embodiment of the present application, the system further includes a first reboiler 108 and a second reboiler 110; The first reboiler 108 is connected to the tower bottom storage tank of the low-temperature catalytic desorption tower 100, and is used to heat the absorbent in the low-temperature catalytic desorption tower 100 to maintain the tower temperature of the low-temperature catalytic desorption tower at 80-95 degrees Celsius; The second reboiler 110 is connected to the tower bottom storage tank of the high-temperature thermal desorption tower 102, and is used to heat the absorbent in the high-temperature thermal desorption tower 102 to maintain the tower temperature of the high-temperature thermal desorption tower at 95-110 degrees Celsius.

[0034] In an embodiment of the present application, the system further comprises a first reboiler 108 and a second reboiler 110, both of which are shell-and-tube heat exchangers. The inlet and outlet of the first reboiler 108 are connected to the bottom tank of the low-temperature catalytic desorption tower 100 through pipelines to form a circulation loop for heating the absorbent in the bottom tank of the low-temperature catalytic desorption tower 100 to maintain the preset first desorption temperature in the tower. The inlet and outlet of the second reboiler 110 are connected to the bottom tank of the high-temperature thermal desorption tower 102 through pipelines to also form a circulation loop for heating the absorbent in the bottom tank of the high-temperature thermal desorption tower 102 to maintain the preset second desorption temperature in the tower. The heating medium of the reboilers is steam or high-temperature heat-conducting oil, and the flow rate of the heating medium can be adjusted to accurately control the temperature in the tower.

[0035] The independent arrangement of the first reboiler 108 and the second reboiler 110 enables accurate control of the temperatures of the two desorption towers, respectively meets the temperature requirements of low-temperature catalytic desorption and high-temperature thermal desorption, and ensures stable implementation of the cascade desorption process. The circulation heating mode makes the temperature of the absorbent in the bottom tank uniform, avoids local overheating or insufficient temperature, ensures stable desorption reaction rate, and improves the consistency of desorption effect. The reboilers have high heat exchange efficiency, can quickly heat the absorbent to the target temperature, shorten the start-up time, and the flow rate of the heating medium can be flexibly adjusted to adjust the temperature in real time according to the desorption state of the absorbent, adapt to the operation requirements under different loads. The independent heating design avoids mutual interference of the temperatures of the two towers, further improves the stability and reliability of the system operation, and reduces energy waste.

[0036] According to an embodiment of the present application, the solid acid catalyst packing layer in the low-temperature catalytic desorption tower 100 is composed of a solid acid desorption catalyst and an inert component mixed according to a preset ratio.

[0037] In an embodiment of the present application, the solid acid catalyst packing layer in the low-temperature catalytic desorption tower 100 is composed of a solid acid desorption catalyst and an inert component mixed according to a preset ratio. The solid acid desorption catalyst is a solid acid material with high catalytic activity, which can reduce the activation energy of the absorbent desorption reaction and promote rapid desorption of carbon dioxide. The inert component is an inert material with stable chemical properties and strong heat resistance, and the particle shape of the inert component is adapted to that of the solid acid desorption catalyst. After mixing, a packing layer with loose structure is formed. During the mixing process, the two components are uniformly distributed without agglomeration, the porosity of the packing layer is moderate, which ensures smooth flow of the absorbent and prolongs the contact time of the absorbent and the catalyst.

[0038] The high catalytic activity of the solid acid desorption catalyst enables the desorption reaction of the absorbent at a lower temperature, significantly reduces the first desorption temperature, and reduces the heating energy consumption. The addition of the inert component can effectively prevent the agglomeration of the catalyst particles, maintain the loose structure of the packing layer, reduce the flow resistance of the absorbent, avoid excessive pressure drop in the tower, and improve the flow efficiency of the absorbent. The porosity of the mixed packing layer is reasonably designed, prolonging the contact time of the absorbent and the catalyst, ensuring that the desorption reaction is fully carried out, and improving the desorption rate at low temperature. The inert component has strong chemical stability and heat resistance, which can protect the catalyst from high temperature or impurities, prolong the service life of the catalyst, reduce the replacement frequency and maintenance cost of the catalyst, and at the same time, does not affect the catalytic reaction.

[0039] According to an embodiment of the present application, the top of the low-temperature catalytic desorption tower 100 and the top of the high-temperature thermal desorption tower 102 are provided with liquid distribution devices 112, which are connected with the absorbent liquid inlets 106 of the respective tower tops, for uniformly spraying the absorbent to the solid acid catalyst packing layer or the ordinary packing layer.

[0040] In an embodiment of the present application, the top of the low-temperature catalytic desorption tower 100 and the top of the high-temperature thermal desorption tower 102 are fixedly installed with liquid distribution devices 112. The liquid distribution device 112 is a multi-hole spraying structure, which is sealingly connected with the absorbent liquid inlet 106 of the respective tower top. After the absorbent enters the liquid distribution device 112 through the liquid inlet, it is uniformly sprayed to the lower packing layer through the multi-hole spray head. The number and aperture of the spray head of the liquid distribution device 112 are designed according to the tower body diameter and the packing layer area, to ensure that the spraying range covers the entire packing layer without dead angle. The spraying angle of the spray head is optimized to make the absorbent cover the packing surface in the form of uniform liquid film, avoiding local liquid concentration or omission.

[0041] The uniform spraying function of the liquid distribution device 112 enables the absorbent to fully contact with the packing layer, maximizes the mass transfer area, improves the desorption reaction rate, avoids incomplete local desorption caused by uneven distribution of the absorbent, and improves the overall desorption efficiency. The covering mode in the form of liquid film reduces the flow speed of the absorbent, prolongs the contact time with the packing, and further promotes the desorption reaction. The dead angle-free spraying design ensures that the entire packing layer participates in the mass transfer process, avoids waste of the packing, and improves the utilization rate of the packing. The liquid distribution device 112 has simple structure, is not easy to be blocked, is convenient to maintain, can be stably operated for a long time, ensures the consistency of the system desorption effect, and is suitable for continuous production requirements.

[0042] According to an embodiment of the present application, the system further comprises a first conveying pump 114 and a second conveying pump 116; The outlet of the first conveying pump 114 is connected with the absorbent liquid inlet 106 at the top of the low-temperature catalytic desorption tower 100, for pumping the saturated absorbent; The second delivery pump 116 is installed on the pipeline connecting the absorbent liquid outlet 104 of the low-temperature catalytic desorption tower 100 and the absorbent liquid inlet 106 of the high-temperature thermal desorption tower 102, and is used to deliver the absorbent after low-temperature catalytic desorption.

[0043] In one embodiment of the present invention, the system further includes a first transfer pump 114 and a second transfer pump 116, both of which are corrosion-resistant centrifugal pumps with stable delivery capabilities. The inlet of the first transfer pump 114 is connected to an external saturated absorbent storage device, and its outlet is sealed to the absorbent liquid inlet 106 at the top of the low-temperature catalytic desorption tower 100 via a pipeline, for continuously pumping the saturated absorbent that has absorbed carbon dioxide to the low-temperature catalytic desorption tower 100. The second transfer pump 116 is installed on the pipeline connecting the absorbent liquid outlet 104 of the low-temperature catalytic desorption tower 100 and the absorbent liquid inlet 106 of the high-temperature thermal desorption tower 102. Its inlet is connected to the absorbent liquid outlet 104 pipeline of the low-temperature catalytic desorption tower 100, and its outlet is connected to the absorbent liquid inlet 106 pipeline of the high-temperature thermal desorption tower 102, for stably delivering the semi-lean absorbent after low-temperature catalytic desorption to the high-temperature thermal desorption tower 102.

[0044] The first transfer pump 114 provides stable power for the saturated absorbent to enter the low-temperature catalytic desorption tower 100, ensuring continuous and controllable feed flow, adapting to different throughput requirements, and preventing feed interruptions from affecting the desorption process. The second transfer pump 116 effectively overcomes pipeline resistance, rapidly transporting the semi-lean absorbent to the high-temperature thermal desorption tower 102, ensuring material balance between the two towers, and preventing absorbent accumulation in the low-temperature catalytic desorption tower 100 or insufficient feed to the high-temperature thermal desorption tower 102. The selection of corrosion-resistant centrifugal pumps is adapted to the chemical properties of the absorbent, avoiding pump body corrosion, extending service life, and ensuring stable operation, low noise, and low maintenance costs. Independent control of the two transfer pumps allows the feed flow rate to be adjusted in real time according to the desorption effect, improving the operational flexibility and stability of the system.

[0045] According to one embodiment of the present invention, both the low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102 are provided with a gas outlet 118 and temperature measuring points and pressure measuring points for monitoring tower temperature and tower pressure.

[0046] In one embodiment of the present invention, both the low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102 are equipped with gas outlets 118 at their tops for discharging carbon dioxide gas generated during desorption. A sealing valve is installed at each gas outlet 118 to control the gas emission rate. Temperature and pressure measuring points are installed on the side walls of both towers. The temperature measuring points are located in the middle of the packed desorption section for real-time monitoring of the temperature in the desorption zone within the tower. The pressure measuring points are located in the middle and at the top of the towers for monitoring the pressure at different heights within the towers. Both the temperature and pressure measuring points are connected to external monitoring equipment to provide real-time feedback of temperature and pressure data, facilitating adjustments to operating parameters by operators.

[0047] The placement of gas outlet 118 at the top of the column ensures timely discharge of carbon dioxide generated during desorption, preventing excessive pressure within the column from affecting the desorption reaction. Simultaneously, the sealed valve controls the discharge rate, adapting to the capabilities of subsequent gas processing equipment. Real-time temperature monitoring at the temperature measurement points accurately reflects the desorption reaction status within the column, allowing operators to maintain the target desorption temperature by adjusting the reboiler's heating power, ensuring stable desorption efficiency. Pressure monitoring at the pressure measurement points promptly detects abnormal pressure drops within the column, preventing system failures due to packing blockage and ensuring safe equipment operation. Real-time temperature and pressure monitoring visualizes the system's operating status, facilitating precise operation and troubleshooting, and enhancing the system's safety and reliability.

[0048] like Figure 2 As shown, a second aspect of the present invention provides a method for carbon dioxide absorbent rich-liquid desorption using the above-described carbon dioxide absorbent rich-liquid dual-tower catalytic desorption system, comprising: Step 10: The saturated absorbent that has absorbed carbon dioxide is transported to the low-temperature catalytic desorption tower 100. The first desorption temperature is controlled in the low-temperature catalytic desorption tower 100 so that the saturated absorbent flows through the solid acid catalyst packing layer for catalytic desorption to obtain a semi-lean liquid absorbent. Step 20: The obtained semi-lean liquid absorbent is transported to the high-temperature thermal desorption tower 102. The second desorption temperature is controlled in the high-temperature thermal desorption tower 102 so that the semi-lean liquid absorbent flows through the ordinary packing layer for thermal desorption to obtain the lean liquid absorbent. The second desorption temperature is higher than the first desorption temperature.

[0049] According to the method for cascade catalytic desorption of rich liquid of carbon dioxide absorbent provided by the second aspect embodiment of the present invention, the first desorption temperature is lower than the traditional single-tower thermal desorption temperature, significantly reducing the heating energy consumption and solving the problem of high energy consumption in the traditional process. The catalytic effect of the solid acid catalyst reduces the activation energy of carbon dioxide desorption, enabling the absorbent to achieve rapid desorption at a lower temperature, improving the decarbonization efficiency per unit time, and shortening the residence time of the absorbent in the tower. The full contact between the catalyst and the absorbent ensures the uniformity of decarbonization, avoiding incomplete desorption of local absorbent and ensuring the quality stability of the semi-lean liquid absorbent, laying a good foundation for subsequent high-temperature thermal desorption. The second desorption temperature is higher than the first desorption temperature, performing deep decarbonization on the semi-lean liquid absorbent, significantly increasing the overall desorption rate, and reducing the carbon dioxide residual amount in the lean liquid absorbent to the lowest level. The ordinary packing layer enhances the turbulence effect of the absorbent, enlarging the heat and mass transfer area, allowing the absorbent to fully exchange heat with the high-temperature environment, ensuring the efficient desorption of the remaining carbon dioxide, and avoiding incomplete desorption caused by insufficient heat transfer. The high-temperature thermal desorption is only carried out on the semi-lean liquid absorbent that has removed a large amount of carbon dioxide. Compared with the traditional single-tower that heats the saturated absorbent at high temperature throughout the process, the load is significantly reduced, further reducing energy consumption waste.

[0050] Please continue to refer to Figure 2 , the method for cascade catalytic desorption of rich liquid of carbon dioxide absorbent provided by the second aspect embodiment of the present invention includes: Step 10: Obtain semi-lean liquid absorbent through low-temperature catalytic desorption Start the conveying equipment and continuously and stably convey the saturated absorbent that has absorbed carbon dioxide to the top of the low-temperature catalytic desorption tower 100. Control the first desorption temperature in the tower through the heating device (such as a reboiler) supporting the low-temperature catalytic desorption tower 100 to maintain the tower internal environment temperature within the range suitable for the activity of the solid acid catalyst. The saturated absorbent flows from the top to the bottom of the tower and evenly flows through the solid acid catalyst packing layer in the tower. The regular structure of the packing layer ensures full contact between the absorbent and the catalyst surface without flow dead ends. Under the catalytic effect of the solid acid catalyst, the binding bond between carbon dioxide and the absorbent in the saturated absorbent is broken, and a large amount of carbon dioxide is rapidly desorbed and released, completing the catalytic desorption process. After being processed by this step, the carbon dioxide content in the absorbent is significantly reduced, forming a semi-lean liquid absorbent, which is finally collected in the bottom storage tank of the low-temperature catalytic desorption tower 100.

[0051] Step 20: Obtain lean liquid absorbent through high-temperature thermal desorption Start the conveying equipment connecting the low-temperature catalytic desorption tower 100 and the high-temperature thermal desorption tower 102, and convey the semi-lean liquid absorbent in the bottom storage tank to the top of the high-temperature thermal desorption tower 102. Control the second desorption temperature in the tower through the heating device supporting the high-temperature thermal desorption tower 102. This temperature is higher than the first desorption temperature. The semi-lean liquid absorbent flows from top to bottom through the common packing layer in the tower. The common packing layer enhances the turbulence degree of the absorbent and expands the contact area between the absorbent and the high-temperature environment in the tower. Under the action of high temperature, the remaining carbon dioxide in the semi-lean liquid absorbent is further desorbed to achieve deep desorption. After being processed by this step, the residual amount of carbon dioxide in the absorbent is reduced to an extremely low level, forming a lean liquid absorbent, which is collected in the bottom storage tank of the high-temperature thermal desorption tower 102 and can be subsequently conveyed to the absorption unit for recycling.

[0052] The two steps form a continuous cascade desorption process. The saturated absorbent first undergoes a large amount of decarbonization through low-temperature catalytic desorption, and then undergoes deep decarbonization through high-temperature thermal desorption, without additional intermediate treatment links. The first desorption temperature and the second desorption temperature are independently regulated by their respective heating devices to ensure that the temperature is stable within the preset range, and the second desorption temperature is always higher than the first desorption temperature to meet the requirements of different desorption stages.

[0053] According to an embodiment of the present invention, the first preset temperature is 80 °C to 95 °C.

[0054] In an embodiment of the present invention, the first desorption temperature in the low-temperature catalytic desorption tower 100 is controlled within the range of 80 °C to 95 °C. Precise temperature control is achieved through the adjustment of the heating power of the first reboiler 108. The flow rate of the heating medium of the first reboiler 108 is adjusted in real time according to the temperature data fed back by the temperature measurement point. When the temperature is lower than 80 °C, the flow rate of the heating medium is increased to enhance the heating intensity; when the temperature is higher than 95 °C, the flow rate of the heating medium is reduced to lower the heating intensity, ensuring that the temperature in the tower is stable within the preset range. During the temperature control process, combined with the feed flow rate and composition of the absorbent, the heating parameters are dynamically optimized to make the temperature match the desorption reaction rate.

[0055] The first desorption temperature range of 80 °C to 95 °C matches the catalytic activity range of the solid acid catalyst, which can maximize the catalytic effect of the catalyst, achieve efficient desorption at a lower temperature, and significantly reduce the heating energy consumption. This temperature range avoids the slow desorption rate caused by too low temperature, and at the same time prevents the energy consumption waste and absorbent degradation caused by too high temperature, prolonging the service life of the absorbent. The stable temperature control makes the catalytic desorption reaction rate uniform, the desorption effect has good consistency, the quality of the semi-lean liquid absorbent is stable, laying a good foundation for the subsequent high-temperature thermal desorption. This temperature range does not require special high-temperature resistant equipment, reducing the equipment material requirements and investment costs, and further improving the economy of the process.

[0056] According to one embodiment of the present invention, the second preset temperature is 95 degrees Celsius to 110 degrees Celsius.

[0057] In one embodiment of the present invention, the second desorption temperature within the high-temperature thermal desorption tower 102 is controlled within the range of 95 degrees Celsius to 110 degrees Celsius. Precise temperature control is achieved by adjusting the heating power of the second reboiler 110. Based on temperature data fed back from the temperature measuring points of the high-temperature thermal desorption tower 102, the supply of the heating medium is adjusted to stabilize the temperature within the preset range. When the feed flow rate or composition of the semi-lean absorbent changes, the heating parameters are adjusted promptly to ensure that the temperature does not deviate from the target range, thus guaranteeing a deep desorption effect.

[0058] The second desorption temperature range of 95°C to 110°C effectively overcomes the desorption equilibrium limitation, enabling deep desorption of the semi-lean absorbent and significantly improving its desorption rate. This minimizes the residual carbon dioxide in the lean absorbent, ensuring that the absorbent's cyclic load remains constant. This temperature range is higher than the first desorption temperature but lower than the traditional single-tower full-process high-temperature desorption temperature, ensuring desorption efficiency while avoiding a surge in energy consumption caused by excessively high temperatures. The stable high-temperature environment allows for rapid desorption of residual carbon dioxide from the semi-lean absorbent, shortening the desorption time, improving treatment efficiency, and ensuring stable quality of the lean absorbent, meeting the requirements for cyclic use of the absorption unit and achieving efficient regeneration of the absorbent.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon dioxide absorbent rich-liquid dual-tower cascade catalytic desorption system, characterized in that, include: A low-temperature catalytic desorption tower (100) is provided with a solid acid catalyst packing layer inside the low-temperature catalytic desorption tower (100), and an absorbent liquid outlet (104) is provided at the bottom of the tower. A high-temperature thermal desorption tower (102) is connected in series with the low-temperature catalytic desorption tower (100). The high-temperature thermal desorption tower (102) is provided with a non-catalytic ordinary packing layer. The top of the high-temperature thermal desorption tower (102) is provided with an absorbent liquid inlet (106). The absorbent liquid outlet (104) of the low-temperature catalytic desorption tower (100) is connected to the absorbent liquid inlet (106) of the high-temperature thermal desorption tower (102) via a pipeline, and is used to transport the absorbent after low-temperature catalytic desorption to the high-temperature thermal desorption tower (102) for high-temperature thermal desorption.

2. The carbon dioxide absorbent rich liquid dual-tower cascade catalytic desorption system according to claim 1, characterized in that, Both the low-temperature catalytic desorption tower (100) and the high-temperature thermal desorption tower (102) include, from bottom to top, a bottom storage tank, a packing desorption section, and a water-cooled purification section; the solid acid catalyst packing layer is located in the packing desorption section of the low-temperature catalytic desorption tower (100), and the ordinary packing layer is located in the packing desorption section of the high-temperature thermal desorption tower (102).

3. The carbon dioxide absorbent rich liquid dual-tower cascade catalytic desorption system according to claim 2, characterized in that, The system also includes a first reboiler (108) and a second reboiler (110). The first reboiler (108) is connected to the bottom storage tank of the low-temperature catalytic desorption tower (100) and is used to heat the absorbent in the low-temperature catalytic desorption tower (100) to maintain the tower temperature of the low-temperature catalytic desorption tower at 80 degrees Celsius to 95 degrees Celsius. The second reboiler (110) is connected to the bottom storage tank of the high-temperature thermal desorption tower (102) and is used to heat the absorbent in the high-temperature thermal desorption tower (102) to maintain the tower temperature of the high-temperature thermal desorption tower at 95 degrees Celsius to 110 degrees Celsius.

4. The carbon dioxide absorbent rich liquid dual-tower cascade catalytic desorption system according to claim 1, characterized in that, The solid acid catalyst packing layer in the low-temperature catalytic desorption tower (100) is composed of a solid acid desorption catalyst and an inert component mixed in a preset ratio.

5. The carbon dioxide absorbent rich liquid dual-tower cascade catalytic desorption system according to claim 1, characterized in that, Both the top of the low-temperature catalytic desorption tower (100) and the top of the high-temperature thermal desorption tower (102) are equipped with liquid distribution devices (112). The liquid distribution devices (112) are connected to the absorbent liquid inlet (106) at the top of their respective towers, and are used to uniformly spray the absorbent onto the solid acid catalyst packing layer or the ordinary packing layer.

6. The carbon dioxide absorbent rich liquid dual-tower cascade catalytic desorption system according to claim 1, characterized in that, The system also includes a first delivery pump (114) and a second delivery pump (116). The outlet of the first delivery pump (114) is connected to the absorbent liquid inlet (106) at the top of the low-temperature catalytic desorption tower (100) for pumping saturated absorbent; The second delivery pump (116) is installed on the pipeline connecting the absorbent liquid outlet (104) of the low-temperature catalytic desorption tower (100) and the absorbent liquid inlet (106) of the high-temperature thermal desorption tower (102) for delivering the absorbent after low-temperature catalytic desorption.

7. The carbon dioxide absorbent rich liquid dual-tower cascade catalytic desorption system according to claim 1, characterized in that, Both the low-temperature catalytic desorption tower (100) and the high-temperature thermal desorption tower (102) are equipped with a gas outlet (118) and temperature and pressure measuring points for monitoring tower temperature and pressure.

8. A method for carbon dioxide absorbent rich-liquid desorption using the carbon dioxide absorbent rich-liquid dual-tower stepped catalytic desorption system according to any one of claims 1 to 7, characterized in that, include: The saturated absorbent that has absorbed carbon dioxide is transported to the low-temperature catalytic desorption tower (100). The first desorption temperature is controlled in the low-temperature catalytic desorption tower (100) so that the saturated absorbent flows through the solid acid catalyst packing layer for catalytic desorption to obtain a semi-lean absorbent. The obtained semi-lean liquid absorbent is transported to the high-temperature thermal desorption tower (102), and the second desorption temperature is controlled in the high-temperature thermal desorption tower (102) so that the semi-lean liquid absorbent flows through the ordinary packing layer for thermal desorption to obtain a lean liquid absorbent. The second desorption temperature is higher than the first desorption temperature.

9. The carbon dioxide absorbent rich liquid dual-tower stepped catalytic desorption method according to claim 8, characterized in that, The first preset temperature is 80 degrees Celsius to 95 degrees Celsius.

10. The carbon dioxide absorbent rich liquid dual-tower stepped catalytic desorption method according to claim 8, characterized in that, The second preset temperature is 95 degrees Celsius to 110 degrees Celsius.

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