Pressure swing adsorption method

Abstract

The invention provides a pressure swing adsorption method which is used for a pressure swing adsorption system comprising at least 12 adsorption towers, and each adsorption tower circularly executes a complete work cycle. The working cycle comprises an adsorption step, an N-time pressure-equalizing and pressure-reducing step, a clockwise releasing step, a reverse releasing step, a washing step, an isolation step, an N-time pressure-equalizing and pressure-increasing step and a final charging step which are circularly operated; wherein N is an integer greater than or equal to 4; wherein at any moment, two of the at least 12 adsorption towers are in the adsorption step at the same time; when one adsorption tower is in the ith pressure-equalizing and pressure-reducing step, the other adsorption tower is in the ith pressure-equalizing and pressure-increasing step, the adsorption tower and the other adsorption tower are communicated for gas conveying, and i is an integer between 1 and N. On the premise of ensuring the product purity, the product yield is obviously improved, the contradiction that the two are difficult to synergistically improve is effectively solved, and the economical efficiency and long-term operation stability of the pressure swing adsorption technology are comprehensively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure swing adsorption, in particular to a pressure swing adsorption method. BACKGROUND

[0002] In gas separation technology, pressure swing adsorption technology has become one of the core technologies of gas separation and purification due to its low energy consumption, simple operation, high automation and other significant advantages. Pressure swing adsorption technology is based on the difference in adsorption capacity of adsorbents for each component in mixed gas under different pressures, and realizes effective separation of gas through periodic pressure change. At present, pressure swing adsorption technology has been maturely applied to the separation and purification of hydrogen, carbon dioxide, carbon monoxide, nitrogen, oxygen, methane and other gases, and the purification of other industrial gases.

[0003] Although pressure swing adsorption technology has become the mainstream method of gas separation, it still faces some bottlenecks in the process of pursuing higher efficiency and economy. First, the existing technology generally has inherent contradiction between product purity and yield. In order to ensure high purity, the yield is often sacrificed, resulting in low utilization rate of raw materials and limiting its economic benefits. Second, most system control schemes rely on fixed time sequence programs, lack adaptive adjustment ability to working condition fluctuations, and are difficult to realize true intelligentization and optimal operation, resulting in low efficiency of the system under non-ideal conditions. In addition, the adsorbent is prone to performance degradation due to pollution or physical wear and tear in long-term operation, and has a short service life, which not only leads to a decrease in product purity. These problems jointly restrict the development of pressure swing adsorption technology towards higher efficiency, lower cost and longer period of stable operation. SUMMARY

[0004] The technical problem to be solved by the present application is how to overcome the limitation that product purity and yield are difficult to be improved simultaneously in the existing pressure swing adsorption technology, and effectively slow down the performance degradation of the adsorbent to prolong its service life, so as to improve the economy and long-term operation stability of the pressure swing adsorption technology.

[0005] In order to solve the above problems, the present application provides a pressure swing adsorption method, which is used in a pressure swing adsorption system comprising at least 12 adsorption towers, each of which cyclically performs a complete working cycle; The working cycle comprises: an adsorption step, N times of equalizing pressure and depressurizing steps, a forward blowdown step, a reverse blowdown step, a flushing step, an isolation step, N times of equalizing pressure and pressurizing steps, and a final charging step, which are cyclically operated; wherein N is an integer greater than or equal to 4; Among them, at any time, at least two of the 12 adsorption towers are simultaneously in the adsorption step; When one adsorption tower is in the i-th equalizing pressure and depressurizing step, another adsorption tower is in the i-th equalizing pressure and pressurizing step, and the two are connected for gas transportation, i is an integer between 1 and N.

[0006] The technical effects achieved by adopting the technical scheme are as follows: the pressure swing adsorption technology sets at least 12 adsorption towers, and designs the cycle time sequence of the 12 adsorption towers, including at least four equalization pressure reduction steps and at least four equalization pressure increase steps, wherein at least two adsorption towers are ensured to be in the adsorption step at any time, and the i th equalization pressure reduction step corresponds to the i th equalization pressure increase step, forming a stepped pressure equalization system, which can maximize the recovery of the potential energy of the high-pressure gas in the adsorption tower during the pressure reduction of the adsorption tower, and is used for the pressure increase of other adsorption towers. Compared with the prior art, the amount of final product gas is greatly reduced, and the loss of gas in the equalization step is also reduced. Under the premise of ensuring the purity of the product, the yield of the product is significantly improved, and the contradiction between the two is effectively solved. Moreover, the multi-stage and gentle equalization pressure and pressure reduction process significantly slows down the change rate of the pressure in the tower, avoids the high-speed impact of the gas flow caused by the sharp pressure drop, effectively inhibits the "fluidization" phenomenon of the adsorption bed, minimizes the disturbance of the adsorption bed and the mutual friction between particles, thereby greatly slowing down the physical wear and powdering rate of the adsorption agent, significantly prolonging the service life of the adsorption agent, and comprehensively improving the economy and long-term operation stability of the pressure swing adsorption technology.

[0007] Optionally, when one adsorption tower is in the equalization step, another adsorption tower is in the flushing step, and the two are connected for gas transmission.

[0008] The technical effects achieved by adopting the technical scheme are as follows: through the correspondence between the equalization step and the flushing step, the gas output by the equalization tower is directly and efficiently used for the regeneration of the adsorbent of the flushing tower, and a self-balancing internal gas source circulation is constructed. This not only recycles the energy of the equalization gas that would otherwise be wasted, significantly reducing the external energy consumption of the flushing process, but also provides a stable and continuous flushing gas source, ensuring that the adsorbent bed is deeply and uniformly desorbed, thereby further improving the purity of the final product and reducing the overall operation energy consumption of the pressure swing adsorption technology system.

[0009] Optionally, the starting pressure in the i th step is greater than the starting pressure in the i+1 th equalization pressure reduction step, and the ending pressure in the i th equalization pressure reduction step is greater than the ending pressure in the i+1 th equalization pressure reduction step.

[0010] The technical effects achieved by the technical scheme are as follows: the starting pressure in the i-th equalization and pressure reduction step is greater than the starting pressure in the (i+1)-th equalization and pressure reduction step, the ending pressure in the i-th equalization and pressure reduction step is greater than the ending pressure in the (i+1)-th equalization and pressure reduction step, a multi-stage ladder type pressure equalization system is realized by establishing a step-by-step decreasing equalization and pressure reduction step, the pressure potential energy contained in the high-pressure gas in the pressure reduction tower is maximally recovered, and the pressure potential energy is efficiently used for step-by-step pressure increase of other adsorption towers, and therefore the economy and long-term operation stability of the pressure swing adsorption technology are further improved.

[0011] Optionally, the starting pressure in the i-th equalization and pressure increase step is less than the starting pressure in the (i+1)-th equalization and pressure increase step, and the ending pressure in the i-th equalization and pressure increase step is less than the ending pressure in the (i+1)-th equalization and pressure increase step.

[0012] The technical effects achieved by the technical scheme are as follows: the starting pressure in the i-th equalization and pressure increase step is less than the starting pressure in the (i+1)-th equalization and pressure increase step, and the ending pressure in the i-th equalization and pressure increase step is less than the ending pressure in the (i+1)-th equalization and pressure increase step, a more efficient ladder type pressure equalization system is constructed by establishing a step-by-step increasing equalization and pressure increase step, and a higher level is achieved in energy recovery and product yield, and the long-term operation reliability and economy of the system are improved by protecting the core adsorption material.

[0013] Optionally, the time of the forward blowdown step is equal to the time of the reverse blowdown step.

[0014] The technical effects achieved by the technical scheme are as follows: by making the time of the forward blowdown step equal to the time of the reverse blowdown step, product gas waste is avoided under the premise of ensuring that the adsorbent bed is fully and efficiently regenerated, and finally the product purity and recovery rate are simultaneously optimized, and the operation stability and controllability of the process are enhanced.

[0015] Optionally, the time of the adsorption step> the time of the flushing step> the time of the forward blowdown step> the time of the final charging step.

[0016] The technical effects achieved by the technical scheme are as follows: by the time of the adsorption step> the time of the flushing step> the time of the forward blowdown step> the time of the final charging step, a stable and efficient pressure swing adsorption method is formed.

[0017] Optionally, N is 5, that is, there are five equalization and pressure reduction steps and five equalization and pressure increase steps in the pressure swing adsorption method, a more efficient five-stage ladder type pressure equalization system is constructed, and product yield maximization, product purity optimization, operation energy consumption minimization, and system service life maximization are realized.

[0018] Optionally, the pressure swing adsorption system includes 12 adsorption towers, and the specific steps of the pressure swing adsorption method are shown in the following table: Among them, the 12 adsorption towers are: T201A, T201B, T201C, T201D, T201E, T201F, T201G, T201H, T201I, T201J, T201K, T201L. A: adsorption step; ED1: first equalization pressure reduction step; E2D: second equalization pressure reduction step; E3D: third equalization pressure reduction step; E4D: fourth equalization pressure reduction step; E5D: fifth equalization pressure reduction step; PP: forward blowdown step; D: reverse blowdown step; P: purge step; E5R: fifth equalization pressure increase step; E4R: fourth equalization pressure increase step; E3R: third equalization pressure increase step; E2R: second equalization pressure increase step; E1R: first equalization pressure increase step; IS: isolation step; FR: final charging step.

[0019] The technical effects achieved after adopting the technical scheme are: through specific design of the cycle timing of the 12 adsorption towers, the 12 adsorption towers execute the same step sequence, and there is a time difference, which ensures that at any given time point, each step has a specific number of adsorption towers executing in the system, thereby ensuring continuous raw gas entry and product gas output, and realizing steady-state operation of the pressure swing adsorption system.

[0020] Optionally, in the adsorption step, the first equalization pressure reduction step, the second equalization pressure reduction step, the third equalization pressure reduction step, the fourth equalization pressure reduction step, the fifth equalization pressure reduction step, the forward blowdown step, the reverse blowdown step, the purge step, the isolation step, the fifth equalization pressure increase step, the fourth equalization pressure increase step, the third equalization pressure increase step, the second equalization pressure increase step, the first equalization pressure increase step, and the final charging step, the starting pressure, the ending pressure, and the required working time of the corresponding step are: The technical effects achieved after adopting the technical scheme are: by setting the starting pressure, the ending pressure, and the required working time of the corresponding step, each operation is ensured to be accurate, greatly improving the stability and repeatability of the operation of the pressure swing adsorption system.

[0021] Optionally, the forward blowdown gas discharged in the forward blowdown step enters a forward blowdown gas buffer tank, and the desorption gas discharged in the reverse blowdown step enters a tail gas buffer tank.

[0022] The pulse gas released in the instant release step is effectively converted into a continuous regenerative gas source with stable pressure and controllable flow rate by adding a forward release buffer tank. The desorption gas released in the instant release step is effectively converted into a tail gas stream with stable pressure and continuous flow rate by setting a tail gas buffer tank. Not only does this avoid the risk of fluidization and pulverization of the adsorbent bed caused by the direct impact of high-pressure gas flow, but it also protects the physical structure and long-term performance of the adsorbent, and ensures that the regenerative gas can penetrate the entire adsorbent bed at the optimal flow rate and pressure, achieving deep and thorough desorption regeneration. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A process flow chart of the pressure swing adsorption method provided by the embodiments of the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] The embodiments of the present application provide a pressure swing adsorption method, which is used in a pressure swing adsorption system comprising at least 12 adsorption towers, each of which cyclically performs a complete working cycle. The working cycle comprises: an adsorption step, N times of equalizing pressure and depressurizing steps, a forward release step, a reverse release step, a flushing step, an isolation step, N times of equalizing pressure and pressurizing steps, and a final charging step, which are cyclically operated. Wherein N is an integer greater than or equal to 4. At any time, at least two of the 12 adsorption towers are simultaneously in the adsorption step. When one of the adsorption towers is in the i-th equalizing pressure and depressurizing step, another of the adsorption towers is in the i-th equalizing pressure and pressurizing step, and the two are connected for gas transmission, i is an integer between 1 and N.

[0026] The pressure swing adsorption technology sets at least 12 adsorption towers, and designs the cycle timing of the 12 adsorption towers, including at least 4 equalization pressure reduction and at least 4 equalization pressure increase steps, wherein at least two adsorption towers are ensured to be in the adsorption step at any time, and the i-th equalization pressure reduction step corresponds to the i-th equalization pressure increase step, which constitutes a stepped pressure equalization system, can maximize the recovery of the potential energy of the high-pressure gas in the tower during the pressure reduction of the tower, and is used for the pressure increase of other adsorption towers, compared with the prior art, the amount of final product gas is greatly reduced, and the loss of gas in the step is also reduced, under the premise of ensuring the product purity, the product yield is significantly improved, and the contradiction between the two is effectively solved. And this multi-stage, gentle equalization and pressure reduction process significantly slows down the change rate of the pressure in the tower, avoids the high-speed impact of the gas flow caused by the sharp pressure drop, effectively suppresses the "fluidization" phenomenon of the adsorption bed, minimizes the disturbance of the adsorption bed and the mutual friction between the particles, thereby greatly slowing down the physical wear and tear rate of the adsorbent and the powderization rate, prolonging the service life of the adsorbent, and improving the economy and long-term operation stability of the pressure swing adsorption technology.

[0027] In some embodiments of the present application, when one adsorption tower is in the step, another adsorption tower is in the flushing step, and the two are connected for gas transmission. By corresponding the step and the flushing step, the gas output from the step is directly and efficiently used for the regeneration of the adsorbent of the flushing tower, and a self-balancing internal gas source circulation is constructed; this not only recycles the energy of the step gas which would otherwise be wasted, significantly reducing the external energy consumption of the flushing process, but also provides a stable and continuous flushing gas source, ensuring that the adsorbent bed is deeply and uniformly desorbed, thereby further improving the purity of the final product and reducing the overall operation energy consumption of the pressure swing adsorption technology system.

[0028] In some embodiments of the present application, the starting pressure of the i-th step is greater than the starting pressure of the i+1-th equalization pressure reduction step, and the ending pressure of the i-th equalization pressure reduction step is greater than the ending pressure of the i+1-th equalization pressure reduction step. The starting pressure of the i-th equalization pressure reduction step is greater than the starting pressure of the i+1-th equalization pressure reduction step, and the ending pressure of the i-th equalization pressure reduction step is greater than the ending pressure of the i+1-th equalization pressure reduction step, establishing a step-by-step decreasing equalization pressure reduction step, realizing a multi-stage stepped pressure equalization system. This stepped equalization maximizes the recovery of the pressure potential energy contained in the high-pressure gas in the tower during the pressure reduction, and efficiently uses it for the step-by-step pressure increase of other adsorption towers, thereby further improving the economy and long-term operation stability of the pressure swing adsorption technology.

[0029] In some embodiments of the present application, the middle starting pressure of the i-th equalization pressure rising step is less than the middle starting pressure of the (i+1)-th equalization pressure rising step, and the middle ending pressure of the i-th equalization pressure rising step is less than the middle ending pressure of the (i+1)-th equalization pressure rising step. By the middle starting pressure of the i-th equalization pressure rising step being less than the middle starting pressure of the (i+1)-th equalization pressure rising step, and the middle ending pressure of the i-th equalization pressure rising step being less than the middle ending pressure of the (i+1)-th equalization pressure rising step, a more efficient stepwise pressure equalization system is established by establishing an equalization pressure rising step that gradually increases, which not only achieves a higher level in energy recovery and product yield, but also improves the long-term operation reliability and economy of the system by protecting the core adsorbent material.

[0030] In some embodiments of the present application, the time of the forward desorption step is equal to the time of the reverse desorption step. By making the time of the forward desorption step equal to the time of the reverse desorption step, the waste of product gas is avoided while ensuring that the adsorbent bed is fully and efficiently regenerated, ultimately achieving simultaneous optimization of product purity and recovery rate, while enhancing the operation stability and controllability of the process.

[0031] In some embodiments of the present application, the time of the adsorption step > the time of the flushing step > the time of the forward desorption step > the time of the final charging step. By the time of the adsorption step > the time of the flushing step > the time of the forward desorption step > the time of the final charging step, a stable and efficient pressure swing adsorption method is formed.

[0032] In some embodiments of the present application, N is 5, that is, there are five equalization pressure reduction steps and five equalization pressure rising steps in the pressure swing adsorption method, which establishes a more efficient five-stage stepwise pressure equalization system, achieving maximum product yield, optimal product purity, minimum energy consumption, and maximum system life.

[0033] When the pressure swing adsorption system includes 12 adsorption towers and N is 5, the specific steps of the pressure swing adsorption method are shown in the following table: Among them, the 12 adsorption towers are: T201A, T201B, T201C, T201D, T201E, T201F, T201G, T201H, T201I, T201J, T201K, and T201L. A: adsorption step; ED1: first equalization decompression step; E2D: second equalization decompression step; E3D: third equalization decompression step; E4D: fourth equalization decompression step; E5D: fifth equalization decompression step; PP: forward blowdown step; D: reverse blowdown step; P: purge step; E5R: fifth equalization pressurization step; E4R: fourth equalization pressurization step; E3R: third equalization pressurization step; E2R: second equalization pressurization step; E1R: first equalization pressurization step; IS: isolation step; FR: final filling step.

[0034] wherein each of the adsorption towers cyclically performs a complete work cycle, and the work cycle includes an adsorption step, a first equalization decompression step, a second equalization decompression step, a third equalization decompression step, a fourth equalization decompression step, a fifth equalization decompression step, a forward blowdown step, a reverse blowdown step, a purge step, an isolation step, a fifth equalization pressurization step, a fourth equalization pressurization step, a third equalization pressurization step, a second equalization pressurization step, a first equalization pressurization step, and a final filling step, and the pressure at the beginning of each step, the pressure at the end of each step, and the required work time of the corresponding step are as follows: By setting the pressure at the beginning of each step, the pressure at the end of each step, and the required work time of the corresponding step, it is ensured that each operation is accurate, and the stability and repeatability of the operation of the pressure swing adsorption system are greatly improved.

[0035] In some embodiments of the present application, the forward blowdown gas discharged in the forward blowdown step enters a forward blowdown gas buffer tank. By adding the forward blowdown gas buffer tank, the pulse gas released instantaneously in the forward blowdown step, which has a sharp fluctuation in pressure and flow rate, is effectively converted into a continuous regeneration gas source with stable pressure and controllable flow rate. By setting a tail gas buffer tank, the desorption gas released instantaneously in the reverse blowdown step, which has a sharp fluctuation in pressure and flow rate, is effectively converted into a tail gas stream with stable pressure and continuous flow rate. Not only is the risk of fluidization and pulverization of the adsorbent bed caused by the direct impact of the high-pressure gas flow avoided, the physical structure and long-term performance of the adsorbent are protected, but also it is ensured that the regeneration gas can continuously and uniformly penetrate the entire adsorbent bed at the optimal flow rate and pressure, achieving deep and thorough desorption and regeneration.

[0036] The entire process of the cyclic operation of the adsorption equipment for implementing the pressure swing adsorption method of the embodiments of the present application is completed by program control, wherein most of the valves used are program control valves, and the control of the product purity and its flow rate realizes online full-automatic adjustment.

[0037] See the attached Figure 1As shown, the pressure swing adsorption system includes 12 adsorption towers, including adsorption tower T201A, adsorption tower T201B, adsorption tower T201C, adsorption tower T201D, adsorption tower T201E, adsorption tower T201F, adsorption tower T201G, adsorption tower T201H, adsorption tower T201I, adsorption tower T201J, adsorption tower T201K, and adsorption tower T201L, wherein adsorption tower T201B, adsorption tower T201C, adsorption tower T201D, adsorption tower T201E, adsorption tower T201F, adsorption tower T201G, adsorption tower T201H, adsorption tower T201I, adsorption tower T201J, and adsorption tower T201K are in the adsorption step, and adsorption tower T201A and adsorption tower T201L are in the desorption step. Figure 1 One adsorption tower is shown.

[0038] Each step is described in detail as follows, with adsorption tower T201A as an example.

[0039] When the adsorption tower T201A is in the adsorption step, the valve KV201a, the valve KV202a, and the valve KV209 are in the open state, and the remaining valves directly connected to the adsorption tower T201A are in the closed state. The adsorption tower T201A performs adsorption work and pressurizes the adsorption tower T201B and the adsorption tower T201C through the valve KV209 and the valve HV201. The tower state of the adsorption tower T201B and the adsorption tower T201C is the final charging step.

[0040] When the adsorption tower T201A is in the first equalization and pressure reduction step, the valve KV204a is in the open state, and the remaining valves directly connected to the adsorption tower T201A are in the closed state. At the same time, the valve KV204d is in the open state, and the first equalization gas of the adsorption tower T201A enters the adsorption tower T201D. The tower state of the adsorption tower T201D is the first equalization and pressure increase step.

[0041] When the adsorption tower T201A is in the second equalization and pressure reduction step, the valve KV205a is in the open state, and the remaining valves directly connected to the adsorption tower T201A are in the closed state. At the same time, the valve KV205e is in the open state, and the second equalization gas of the adsorption tower T201A enters the adsorption tower T201E. The tower state of the adsorption tower T201E is the second equalization and pressure increase step.

[0042] When the adsorption tower T201A is in the third equalization and pressure reduction step, the valve KV205a is in the open state, and the remaining valves directly connected to the adsorption tower T201A are in the closed state. At the same time, the valve KV205f is in the open state, and the second equalization gas of the adsorption tower T201A enters the adsorption tower T201F. The tower state of the adsorption tower T201F is the third equalization and pressure increase step.

[0043] When the adsorption tower T201A is in the fourth equalization pressure decreasing step, the valve KV206a is in the open state, while the rest of the valves directly connected to the adsorption tower T201A are in the closed state, and the valve KV206g is in the open state, at this time the second equalization pressure gas of the adsorption tower T201A will enter the adsorption tower T201G, and the tower state of the adsorption tower T201G is the fourth equalization pressure increasing step.

[0044] When the adsorption tower T201A is in the fifth equalization pressure decreasing step, the valve KV206a is in the open state, while the rest of the valves directly connected to the adsorption tower T201A are in the closed state, and the valve KV206h is in the open state, at this time the second equalization pressure gas of the adsorption tower T201A will enter the adsorption tower T201H, and the tower state of the adsorption tower T201H is the fifth equalization pressure increasing step.

[0045] When the adsorption tower T201A is in the forward blowdown step, the valve KV207a is in the open state, while the rest of the valves directly connected to the adsorption tower T201A are in the closed state, and the valve KV210 is in the open state, at this time the forward blowdown gas of the adsorption tower T201A will enter the forward blowdown gas buffer tank V201, and the forward blowdown gas in the forward blowdown gas buffer tank V201 enters the adsorption tower J through the valve HV202 and the valve KV208, and the tower state of the adsorption tower T201J is the flushing step.

[0046] When the adsorption tower T201A is in the reverse blowdown step, the valve KV203a is in the open state, while the rest of the valves directly connected to the adsorption tower T201A are in the closed state, and the adsorption tower T201A discharges desorption gas through the gas itself pressure, and the desorption gas enters the tail gas buffer tank V203.

[0047] When the adsorption tower T201A is in the flushing step, the valve KV208a is in the open state, while the rest of the valves directly connected to the adsorption tower T201A are in the closed state, and the forward blowdown gas of the forward blowdown gas buffer tank V201 enters the adsorption tower T201A through the valve HV202.

[0048] When the adsorption tower T201A is in the fifth equalization pressure increasing step, the valve KV206a is in the open state, while the rest of the valves directly connected to the adsorption tower T201A are in the closed state, and the valve KV206f is in the open state, at this time the fifth equalization pressure gas of the adsorption tower T201F will enter the adsorption tower T201A, and the tower state of the adsorption tower T201F is the fifth equalization pressure decreasing step.

[0049] When the adsorption column T201A is in the fourth equalization pressure boosting step, the valve KV206a is in the open state, while the rest of the valves directly connected to the adsorption column T201A are in the closed state, and the valve KV206g is in the open state, at this time the fourth equalization gas of the adsorption column T201G will enter the adsorption column T201A, and the column state of the adsorption column T201G is in the fourth equalization pressure boosting step.

[0050] When the adsorption column T201A is in the third equalization pressure boosting step, the valve KV205a is in the open state, while the rest of the valves directly connected to the adsorption column T201A are in the closed state, and the valve KV205h is in the open state, at this time the third equalization gas of the adsorption column T201H will enter the adsorption column T201A, and the column state of the adsorption column T201H is in the third equalization pressure boosting step.

[0051] When the adsorption column T201A is in the second equalization pressure boosting step, the valve KV205a is in the open state, while the rest of the valves directly connected to the adsorption column T201A are in the closed state, and the valve KV205i is in the open state, at this time the second equalization gas of the adsorption column T201I will enter the adsorption column T201A, and the column state of the adsorption column T201I is in the second equalization pressure boosting step.

[0052] When the adsorption column T201A is in the first equalization pressure boosting step, the valve KV204a is in the open state, while the rest of the valves directly connected to the adsorption column T201A are in the closed state, and the valves KV205j and KV209 are in the open state, at this time the first equalization gas of the adsorption column T201J will enter the adsorption column T201A through the HV201, and the column state of the adsorption column T201J is in the first equalization pressure boosting step.

[0053] When the adsorption column T201A is in the final boosting step, the valve KV204a and the valve KV207 are in the open state, while the rest of the valves directly connected to the adsorption column T201A are in the closed state, and the valves KV206l and KV209 are in the open state, at this time part of the gas of the adsorption column T201L will enter the adsorption column T201A, and the column state of the adsorption column T201L is in the adsorption step.

[0054] When all the above steps are completed, it indicates that a pressure swing adsorption cycle is completed, wherein the valve KV210 serves as a gas release buffer tank gas inlet special valve. The valve HV202 serves as a gas release outlet regulating valve.

[0055] It should be noted that the raw gas from the conversion section enters the adsorption tower through the raw gas main pipeline and the pipeline connected to the bottom of each adsorption tower. When the pressure of a certain adsorption tower reaches the set adsorption pressure, the adsorption tower begins to work. When the adsorption tower is working, the valve KV201 connected to the bottom of the adsorption tower is in an open state, and the product gas valve of the adsorption tower, i.e. the valve KV202, is in an open state. Part of the product gas enters the product gas buffer tank through the valve KV202 and the regulating valve PV201, and the outlet gas of the product gas buffer tank enters the setting device (such as a device using hydrogen) or the section through the regulating valve on the product gas outlet pipeline. Another part of the product gas enters the adsorption tower in the final charging step through the valve KV202, the final rising valve KV209, the regulating valve HV201, and the valve KV204.

[0056] When the actual adsorption working time of the adsorption tower reaches the set adsorption time, the adsorption tower ends the adsorption work and enters the equalization pressure working phase. Because the adsorption pressure of the adsorption tower is high, and in order to ensure the smooth flow of gas in the pipeline and the high adsorption efficiency of the adsorption tower, the number of equalization pressures of each adsorption tower is set to multiple times.

[0057] When the adsorption tower ends the adsorption work and completes the five equalization pressure drop steps, it enters the forward blowdown step. At this time, the forward blowdown valve KV207 is in an open state, and the forward blowdown gas of the adsorption tower enters the forward blowdown gas buffer tank through the forward blowdown valve KV207 and the forward blowdown special valve KV210. After the adsorption tower ends the forward blowdown time, the adsorption tower starts the reverse blowdown step. Reverse blowdown means that the direction of gas entering and leaving the adsorption tower is opposite to that during adsorption, i.e. the gas in the adsorption tower flows from the bottom to the top during adsorption, and the gas in the adsorption tower flows from the top to the bottom during reverse blowdown. During reverse blowdown, the valve KV203 connected to the bottom of the adsorption tower is in an open state, and the reverse blowdown gas in the adsorption tower enters the desorption gas buffer tank through the valve KV203. After the adsorption tower completes the reverse blowdown, it enters the flushing step. At this time, the valve KV208 and the valve KV203 are in an open state, and the flushing gas from the forward blowdown gas buffer tank enters the adsorption tower in the flushing state through the regulating valve HV202 and the valve KV208. After the flushing gas flushes the adsorption tower, it enters the desorption gas buffer tank through the valve KV203. When the flushing is completed, the adsorption tower enters the equalization pressure rising step. After completing the five equalization pressure rising steps, the adsorption tower enters the final charging step. During the final rising, the valve KV202, the valve KV204, and the valve KV209 are in an open state, and part of the product gas from the adsorption tower in the adsorption state enters the adsorption tower in the final rising state through KV202, the valve KV204, and the valve KV209. When the adsorption tower completes the final rising, the adsorption tower meets the requirements of the adsorption work and enters the adsorption step.

[0058] In the above process, the valve opening and closing state corresponds to the state of the adsorption tower, i.e. the corresponding valve is opened when the adsorption tower is in a certain state, and the remaining time is in a closed state.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A pressure swing adsorption method, characterized in that, The pressure swing adsorption method is used in a pressure swing adsorption system comprising at least 12 adsorption towers, each of which cyclically performs one complete working cycle; The working cycle includes: an adsorption step, N equalization and depressurization steps, forward release step, reverse release step, rinsing step, isolation step, N equalization and pressure increase steps, and a final charging step, which are performed cyclically; where N is an integer greater than or equal to 4. At any given time, at least two of the 12 adsorption towers must be simultaneously in the adsorption step. When one of the adsorption towers is in the i-th pressure equalization and depressurization step, there must be another adsorption tower in the i-th pressure equalization and pressurization step, and the two are connected to each other for gas transport, where i is an integer between 1 and N.

2. The pressure swing adsorption method according to claim 1, characterized in that, When one of the adsorption towers is in the cascading step, another adsorption tower must be in the flushing step, and the two are connected to each other for gas delivery.

3. The tower pressure swing adsorption method according to claim 1, characterized in that, The initial pressure in the i-th equalization and pressure reduction step is greater than the initial pressure in the (i+1)-th equalization and pressure reduction step, and the final pressure in the i-th equalization and pressure reduction step is greater than the final pressure in the (i+1)-th equalization and pressure reduction step.

4. The pressure swing adsorption method according to claim 1, characterized in that, The starting pressure in the i-th equalization and pressure rise step is less than the starting pressure in the (i+1)-th equalization and pressure rise step, and the ending pressure in the i-th equalization and pressure rise step is less than the ending pressure in the (i+1)-th equalization and pressure rise step.

5. The pressure swing adsorption method according to claim 1, characterized in that, The time for the forward placement step is equal to the time for the reverse placement step.

6. The pressure swing adsorption method according to claim 5, characterized in that, The time for the adsorption step is greater than the time for the rinsing step, which is greater than the time for the sequential placement step, which is greater than the time for the final charging step.

7. The pressure swing adsorption method according to claim 6, characterized in that, N is 5.

8. The pressure swing adsorption method according to claim 6, characterized in that, The pressure swing adsorption system includes 12 adsorption towers, and the specific steps of the pressure swing adsorption method are shown in the table below: The 12 adsorption towers are: T201A, T201B, T201C, T201D, T201E, T201F, T201G, T201H, T201I, T201J, T201K, and T201L. A: Adsorption step; ED1: First equalization and depressurization step; E2D: Second equalization and depressurization step; E3D: Third equalization and depressurization step; E4D: Fourth equalization and depressurization step; E5D: Fifth equalization and depressurization step; PP: Forward release step; D: Reverse release step; P: Rinsing step; E5R: Fifth equalization and pressurization step; E4R: Fourth equalization and pressurization step; E3R: Third equalization and pressurization step; E2R: Second equalization and pressurization step; E1R: First equalization and pressurization step; IS: Isolation step; FR: Final charging step.

9. The pressure swing adsorption method according to claim 8, characterized in that, In the adsorption step, the first pressure equalization and reduction step, the second pressure equalization and reduction step, the third pressure equalization and reduction step, the fourth pressure equalization and reduction step, the fifth pressure equalization and reduction step, the forward release step, the reverse release step, the rinsing step, the isolation step, the fifth pressure equalization and increase step, the fourth pressure equalization and increase step, the third pressure equalization and increase step, the second pressure equalization and increase step, the first pressure equalization and increase step, and the final charging step, the initial pressure, the final pressure, and the corresponding working time required for each step are as follows:

10. The pressure swing adsorption method according to claim 1, characterized in that, The gas discharged during the forward release step enters the forward release gas buffer tank; the desorbed gas discharged during the reverse release step enters the exhaust gas buffer tank.

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