Automatic control method for pressure swing adsorption process

Abstract

The application provides a kind of automatic control method of pressure swing adsorption process, comprising: automatically adjusting adsorption time: calculate adsorption time according to device load, so as to control the duration of adsorption process;Automatic tower cutting: determine the control valve corresponding to the adsorption tower in the current process, when the actual pressure deviation in the adsorption tower does not meet the requirement of set pressure deviation and the control valve corresponding to the adsorption tower in the current process appears fault alarm, determine that the adsorption tower is fault tower, cut off the fault tower;Automatic adjustment of regulating valve: according to the change of device load, real-time adjust the lower limit of opening value of regulating valve corresponding to pressure increasing process, reverse discharge process, flushing process;Automatic adjustment of resolving gas: calculate the set pressure of resolving gas buffer tank according to device load, pressure value of reverse discharge gas buffer tank at the end of reverse discharge process and reverse discharge gas amount stored in reverse discharge gas buffer tank, make resolving gas output according to calculated set pressure. The degree of automation of pressure swing adsorption process is improved.

Description

Technical Field

[0001] This invention relates to the field of pressure swing adsorption (PSA) technology, and more specifically, to an automatic control method for PSA processes. Background Technology

[0002] With the development and large-scale application of gas pressure swing adsorption (PSA) technology, higher requirements are being placed on the automation level of PSA control. PSA itself is a highly automated sequential control process, with most controls implemented automatically by the control system. However, when abnormal malfunctions or significant fluctuations occur in the equipment, extensive operator intervention is still required to ensure normal and stable operation.

[0003] Therefore, in the current pressure swing adsorption (PSA) process, the automation level of the control system is insufficient for situations with large flow fluctuations and abnormal malfunctions. It is difficult to adjust automatically through the program, and operators need to make judgments based on experience, which is inefficient and has low accuracy. It is also difficult to switch the PSA process system to normal working state in a timely manner, resulting in poor stability. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems in the prior art: insufficient automation of the pressure swing adsorption process control system in the face of large flow fluctuations and abnormal failures; difficulty in automatic adjustment by the program; need for operators to make judgments based on experience; low efficiency and accuracy; difficulty in switching the pressure swing adsorption process system to normal working state in a timely manner; and poor stability.

[0005] Therefore, the present invention provides an automatic control method for pressure swing adsorption process.

[0006] This invention provides an automatic control method for a pressure swing adsorption (PSA) process. The PSA process includes an adsorption step, a depressurization step, a forward discharge step, a reverse discharge step, a rinsing step, and a pressurization step. The automatic control method includes:

[0007] Automatic adjustment of adsorption time: The adsorption time is calculated based on the device load, and the duration of the adsorption process is controlled by the calculated adsorption time.

[0008] Automatic tower cut-off: Identify the control valve corresponding to the adsorption tower in the current process. When the actual pressure deviation in the adsorption tower does not meet the set pressure deviation requirement and the control valve corresponding to the adsorption tower in the current process has a fault alarm, the adsorption tower is determined to be a faulty tower and the faulty tower is cut off.

[0009] Automatic adjustment of regulating valves: Based on changes in the unit load, the lower limit of the opening value of the regulating valves corresponding to the pressurization process, the reverse discharge process, and the flushing process is adjusted in real time;

[0010] Automatic adjustment of desorption gas: The set pressure of the desorption gas buffer tank is calculated based on the unit load, the pressure value of the desorption gas buffer tank at the end of the desorption process, and the amount of desorption gas stored in the desorption gas buffer tank, so that the desorption gas is delivered to the converter according to the calculated set pressure.

[0011] The automatic control method for pressure swing adsorption process according to the above-described technical solution of the present invention may also have the following additional technical features:

[0012] In the above technical solution, the method for calculating the adsorption time based on the device load is as follows:

[0013]

[0014] Among them, T 实际 T represents the current adsorption time. 设计 The adsorption time corresponding to the full load of the feed gas in the process design; F 设计 The full-load flow rate of the feed gas designed for the process; F 实际 K represents the average flow rate of the feed gas over one adsorption cycle. T This is the time coefficient.

[0015] In the above technical solution, the automatic adjustment of adsorption time also includes adjusting the time coefficient according to the quality of the product gas.

[0016] In the above technical solution, the method for calculating the actual pressure deviation is as follows: At the instant the adsorption tower transitions from one process to another, the pressure value P1 inside the adsorption tower is obtained. At regular intervals, the pressure value P2 inside the adsorption tower is taken, and the actual pressure deviation ΔP is calculated. 实际 =|P2-P1|;

[0017] The set pressure deviation is the alarm pressure deviation value set for each process based on the actual operating conditions;

[0018] When the actual pressure deviation is greater than or less than the set pressure deviation, the adsorption tower will trigger a pressure alarm.

[0019] In the above technical solution, the control valves corresponding to the adsorption tower in the adsorption process include: adsorption tower inlet valve, adsorption tower exhaust valve, and adsorption tower equalization / final rise valve.

[0020] The control valves corresponding to the adsorption tower in the pressure reduction and pressure boosting processes include: adsorption tower inlet valve, adsorption tower exhaust valve, adsorption tower first equalization / final boost valve, and adsorption tower second equalization / third equalization valve.

[0021] The control valves corresponding to the adsorption tower in the rinsing process include: adsorption tower rinsing inlet valve, adsorption tower rinsing exhaust valve, and adsorption tower backflow valve.

[0022] In the above technical solution, after automatic tower cutting, the fault is first dealt with, and then the pressure in the faulty tower is reduced to the pressure value of the adsorption tower in the reverse release process, and the reverse release process is executed to realize the recovery after tower cutting.

[0023] In the above technical solution, among the automatically adjusting regulating valves, the regulating valves related to the pressurization process include the adsorption tower equalization / final pressurization regulating valve. The calculation method for the lower limit of the opening value of the adsorption tower equalization / final pressurization regulating valve is as follows:

[0024] E1_L=(K1*F1) / (KT*K)+K2-K4;

[0025] The regulating valves related to the reverse discharge process include the reverse discharge regulating valve and the pressure regulating valve after the reverse discharge gas buffer tank. The calculation method for the lower limit of the opening value of the reverse discharge regulating valve is as follows:

[0026] D_L = (K5*F1) / (K2*K) + K6;

[0027] The calculation method for the lower limit of the opening value of the pressure regulating valve after the reverse venting buffer tank is as follows:

[0028] N_L = (K9*F1) / (K2*K) + K10;

[0029] The regulating valves corresponding to the rinsing process include rinsing regulating valves. The calculation method for the lower limit of the opening value of the rinsing regulating valve is as follows:

[0030] PP_L = (K7*F1) / (K2*K) + K8;

[0031] Where K is the flow rate corresponding to a 1.0% change in valve output; K1, K5, K7, and K9 are flow rate correction coefficients; K T K1 represents the time coefficient; K2, K4, K6, K8, and K10 are the valve output fine-tuning values; and F1 is the average flow rate of the raw gas within one cycle.

[0032] In the above technical solution, the calculation method for the set pressure of the desorption gas buffer tank is as follows:

[0033]

[0034] Wherein, N1 is the amount of reverse venting stored in the reverse venting buffer tank; N2 is the actual pressure value of the reverse venting buffer tank at the end of the reverse venting process; N3 is the ideal pressure value of the reverse venting buffer tank at the end of the reverse venting process; N4 is the adjustment coefficient; T A SP1 represents the adsorption cycle time; SP1 is the SP value of the previous cycle.

[0035] The above technical solution also includes:

[0036] Automatic pressure adjustment of the reverse venting buffer tank: Within T seconds of the start of the reverse venting process, the desorption gas pressure regulating valve opens to the lower limit of its opening value. After T seconds of the start of the reverse venting process, the opening of the desorption gas pressure regulating valve is automatically adjusted according to the desorption gas pressure setting value.

[0037] The above technical solution also includes:

[0038] Automatic switching of regulating valves: Backup valves are added to the equalization / final rise regulating valve, reverse discharge regulating valve and flushing regulating valve of the adsorption tower. When the output value of the regulating valve does not meet the set value requirement, the valve is judged to be faulty based on the valve opening signal and whether the actual pressure deviation in the adsorption tower meets the set pressure deviation requirement. When the regulating valve is faulty, it is switched to the corresponding backup valve.

[0039] In summary, due to the adoption of the above-mentioned technical features, the beneficial effects of the present invention are:

[0040] It can basically realize the fully automated control of the pressure swing adsorption process. Throughout the entire pressure swing adsorption process, the smooth transition of pressure swing adsorption under different operating conditions can be completed without human intervention, reducing the degree of operator involvement, improving work efficiency and reducing error rate, and ensuring the stable operation of the pressure swing adsorption process.

[0041] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0043] Figure 1 This is a schematic diagram of the valve arrangement in a pressure swing adsorption process according to one embodiment of the present invention;

[0044] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0045] Figure 3 yes Figure 1 A magnified view of a section at point B in the middle;

[0046] Figure 4 yes Figure 1 A magnified view of a section at point C.

[0047] in, Figures 1 to 4 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0048] 1. Raw material gas buffer tank; 2. Adsorption tower; 3. Forward venting tank; 4. Backward venting buffer tank; 5. Desorbed gas mixing tank; 6. Raw material gas overpressure venting regulating valve; 7. Adsorption tower inlet valve; 8. Adsorption tower flushing exhaust valve; 9. Adsorption tower backflow valve; 10. Adsorption tower exhaust valve; 11. Adsorption tower primary equalization / final rise valve; 12. Adsorption tower secondary equalization / tertiary equalization valve; 13. Adsorption tower flushing inlet valve; 14. Adsorption tower tertiary equalization / forward venting valve; 15. Adsorption tower primary equalization / final rise regulating valve; 16. Flushing regulating valve; 17. Forward venting tank forward venting valve; 18. Adsorption tower working pressure regulating valve; 19. Product gas overpressure venting regulating valve; 20. Backward venting regulating valve; 21. Desorbed gas pressure regulating valve; 22. Desorbed gas overpressure venting regulating valve; 23. Desorbed gas outlet pressure regulating valve. Detailed Implementation

[0049] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0050] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0051] The following reference Figures 1 to 4 This describes an automatic control method for a pressure swing adsorption process provided according to some embodiments of the present invention.

[0052] Some embodiments of this application provide an automatic control method for a pressure swing adsorption process.

[0053] The pressure swing adsorption (PSA) process mainly includes an adsorption step, a depressurization step, a forward release step, a reverse release step, a rinsing step, and a pressurization step. The adsorption step involves the feed gas entering the adsorption bed of adsorption tower 2 at room temperature and high pressure, where the adsorbent adsorbs impurities to obtain product hydrogen. The depressurization step involves one or more pressure equalization and depressurization processes to recover hydrogen from the dead space in the bed. The reverse release step involves depressurizing against the adsorption direction to partially regenerate the adsorbent. The rinsing step involves rinsing with product hydrogen to reduce the partial pressure of impurities, allowing the adsorbent to complete its final regeneration. The pressurization step involves one or more pressure equalization and pressurization processes and product gas pressurization processes to raise the pressure in adsorption tower 2 to the adsorption pressure, preparing for the next adsorption cycle.

[0054] In one embodiment, the pressure swing adsorption (PSA) process includes thirteen process steps: adsorption, primary equalization depressurization, secondary equalization depressurization, tertiary equalization depressurization, quaternary equalization depressurization, forward release, reverse release, rinsing, quaternary equalization boost, tertiary equalization boost, secondary equalization boost, primary equalization boost, and final boost of product hydrogen. Primary equalization depressurization, secondary equalization depressurization, tertiary equalization depressurization, and quaternary equalization depressurization are four sequentially arranged depressurization steps; quaternary equalization boost, tertiary equalization boost, tertiary equalization boost, and primary equalization boost are four sequentially arranged pressurization steps; the final boost is the last pressurization process, i.e., the quaternary equalization boost. A schematic diagram of the valve arrangement in this process is shown below. Figures 1 to 4 As shown, it includes:

[0055] Raw material gas buffer tank 1: Used to stabilize the pressure of raw material gas;

[0056] Adsorption tower 2: Used to adsorb impurity gases in the raw material gas;

[0057] Flow gas tank 3: Used to collect part of the product gas and use it to flush the impurity gas in adsorption tower 2;

[0058] Reverse venting buffer tank 4: Used to collect high-pressure impurity gas and depressurize it before transporting it out.

[0059] Desorption gas mixing tank 5: Used to collect impurity gas after flushing adsorption tower 2 with gas tank 3;

[0060] Raw material gas overpressure venting regulating valve 6: used for overpressure venting of raw material gas, protecting raw material gas buffer tank 1 and preventing excessively high raw material gas pressure;

[0061] Adsorption tower inlet valve 7: a shut-off valve for raw material gas entering adsorption tower 2;

[0062] Adsorption tower flushing exhaust valve 8: An exhaust shut-off valve used for flushing and regenerating adsorption tower 2;

[0063] Adsorption tower backflow valve 9: A shut-off valve used for backflow of adsorption tower 2;

[0064] Adsorption tower exhaust valve 10: a shut-off valve for product gas exiting adsorption tower 2;

[0065] Adsorption tower 1 equalization / final pressure rise valve 11: a shut-off valve used for the first equalization and final pressure rise of adsorption tower 2;

[0066] Adsorption tower second / third equalization valve 12: a shut-off valve used for the second and third pressure equalization of adsorption tower 2;

[0067] Adsorption tower flushing inlet valve 13: an inlet shut-off valve used for flushing and regenerating adsorption tower 2;

[0068] Adsorption tower fourth equalization / forward discharge valve 14: a shut-off valve used for the fourth equalization of pressure in adsorption tower 2 and for equalizing the pressure of gas into the forward discharge gas tank 3;

[0069] Adsorption tower pressure equalization / final pressure increase regulating valve 15: a control regulating valve used for pressure regulation during the pressure equalization and final pressure increase processes of adsorption tower 2;

[0070] Flushing regulating valve 16: Adjusts the flushing pressure during the flushing process of adsorption tower 2 to stabilize it within a certain pressure range;

[0071] 17: When the adsorption tower 2 is discharged in the forward direction, the gas is released into the required forward discharge gas tank 3;

[0072] Adsorption tower working pressure regulating valve 18: Regulates the pressure of adsorption tower 2 during the adsorption process;

[0073] Product gas overpressure relief regulating valve 19: During the operation of adsorption tower 2, when the product gas pressure exceeds the pressure set value, the pressure is regulated and air is prevented.

[0074] Reverse discharge regulating valve 20: This is the process by which the pressure inside the adsorption tower 2 is reduced to a certain pressure in the opposite direction of adsorption after the forward discharge process is completed. At this time, the adsorbed impurities begin to desorb from the adsorbent.

[0075] Desorption gas pressure regulating valve 21: Regulate the reverse venting pressure and place it into the desorption gas mixing tank;

[0076] Desorption gas overpressure relief regulating valve 22: When the pressure of the desorption gas buffer tank exceeds the set value, the pressure is regulated and the gas is released;

[0077] Desorption gas outlet pressure regulating valve 23: Regulates the stable delivery of desorption gas to the outlet device.

[0078] The following section uses the pressure swing adsorption (PSA) process as an example to introduce the automatic control method of the PSA process in some embodiments.

[0079] The first embodiment of the present invention proposes an automatic control method for a pressure swing adsorption process, including automatic adjustment of adsorption time, automatic tower cutting, automatic adjustment of regulating valves, and automatic adjustment of desorption gas.

[0080] The automatic adjustment of adsorption time involves calculating the adsorption time based on the unit load and using this calculated time to control the duration of the adsorption process. Specifically, the method for calculating the adsorption time based on the unit load is as follows:

[0081]

[0082] Among them, T 实际 T represents the current adsorption time. 设计 The adsorption time corresponding to the full load of the feed gas in the process design; F 设计 The full-load flow rate of the feed gas designed for the process; F 实际 K represents the average flow rate of the feed gas over one adsorption cycle. TThis is the time coefficient.

[0083] In some embodiments, automatic adjustment of the adsorption time also includes automatically adjusting the time coefficient based on the quality of the product gas. That is, when the impurity content in the product gas is greater than a set value, the time coefficient K can be appropriately reduced. T This shortens the adsorption time and increases the purity of the product gas; conversely, if the product purity is too high, the time coefficient K can be appropriately increased. T This extends the adsorption time and improves the recovery rate of the device. After each adjustment of the adsorption time, a certain amount of time needs to be waited for the changes to be reflected in the product gas; therefore, the time coefficient K is automatically adjusted. T After that, a certain amount of time must be waited before the next adjustment can be made. Additionally, the time coefficient K... T Upper and lower limits must be set to prevent the adsorbent from penetrating when errors occur in the analyzer.

[0084] The automatic tower switching method is to determine the control valve corresponding to adsorption tower 2 in the current process. When the actual pressure deviation in adsorption tower 2 does not meet the set pressure deviation requirement and the control valve corresponding to adsorption tower 2 in the current process has a fault alarm, adsorption tower 2 is determined to be a faulty tower and the faulty tower is switched off.

[0085] The actual pressure deviation is calculated as follows: When adsorption tower 2 transitions from one process to another, the pressure value P1 inside adsorption tower 2 is obtained. At regular intervals, i.e., when the operating time exceeds the set deviation alarm judgment time, the pressure value P2 inside adsorption tower 2 is taken. The deviation alarm judgment time is set by the operator; in some embodiments, it is set to 10-20 seconds. Therefore, the actual pressure deviation ΔP is calculated. 实际 =|P2-P1|; The value of P2 is continuously updated as the running time increases, and the actual pressure deviation also changes accordingly.

[0086] Set pressure deviation ΔP 设定 The alarm pressure deviation values ​​for each process are set based on actual operating conditions; in some processes, when ΔP 实际 >ΔP 设定 At that time, adsorption tower 2 triggered a pressure alarm; in other processes, when ΔP 实际 <ΔP 设定 At that time, the adsorption tower 2 triggered a pressure alarm.

[0087] The automatic tower-switching function is the most important part of the automatic adsorption process. Its purpose is to cut off the adsorption tower 2 corresponding to the faulty valve when the control valve of a certain adsorption tower 2 fails, so as not to affect the quality of the product gas and the stability of the unit.

[0088] The main types of valve malfunctions are as follows:

[0089] (1) Opening failure, that is, the valve does not open when it should open.

[0090] (2) Closure failure, that is, the valve fails to close when it should close.

[0091] (3) Feedback failure, that is, the valve is open and closed normally, but the valve feedback signal does not change due to the valve's operation, or the feedback signal does not correspond to the valve's open and closed state.

[0092] Of the three types of faults mentioned above, only the "feedback fault" will not have any impact on the device. The other two types of faults will have a certain impact on the pressure of the device. Therefore, relying solely on valve feedback detection is not enough to truly determine whether there is a fault. Pressure alarms are also needed to confirm which type of fault the valve is experiencing.

[0093] The following analysis examines the state of adsorption tower 2 in different processes:

[0094] (1) Adsorption process

[0095] The main opening and closing actions of the control valves corresponding to adsorption tower 2 in the adsorption process are: opening the adsorption tower inlet valve 7, opening the adsorption tower exhaust valve 10, and closing the adsorption tower equalization / final rise valve 11.

[0096] Fault Analysis:

[0097] a) When the inlet valve 7 of the adsorption tower malfunctions, the raw material gas pressure will increase, the pressure of adsorption tower 2 will decrease, the product gas pressure will decrease, and the pressure difference across the unit will increase.

[0098] b) When the exhaust valve 10 of the adsorption tower malfunctions, the pressure of the raw material gas increases, the pressure of adsorption tower 2 increases, the pressure of the product gas decreases, and the pressure difference across the unit increases.

[0099] c) When the equalization / final riser valve 11 of the adsorption tower 1 malfunctions, the raw material gas pressure will decrease, the pressure of adsorption tower 2 will decrease, the product gas pressure will also decrease, and the pressure difference before and after the unit will not change much.

[0100] Automatic tower switching judgment method:

[0101] a) When ΔP 实际 >ΔP 设定 If a pressure alarm is triggered, and at the same time, if any valve in the tower malfunctions and triggers an alarm, the program will automatically shut down the tower.

[0102] b) When the adsorption tower inlet valve 7 or adsorption tower exhaust valve 10 malfunctions, and the pressure difference across the pressure swing adsorption unit exceeds the set alarm value (the set value varies depending on the unit load), the program will automatically shut down the tower.

[0103] (2) Pressure reduction process / Pressure boosting process (first step)

[0104] The main opening and closing actions of the control valves corresponding to adsorption tower 2 in the pressure reduction / pressure increase process are: closing the adsorption tower inlet valve 7, closing the adsorption tower exhaust valve 10, closing the adsorption tower secondary / tertiary equalization valve 12, and opening the adsorption tower primary equalization / final rise valve 11.

[0105] Fault Analysis:

[0106] a) When the equalization / final rise valve 11 of the adsorption tower 1 malfunctions, the pressure of the corresponding adsorption tower 2 will not change, that is, the equalization rise valve will not increase the pressure, and the equalization fall valve will not decrease the pressure.

[0107] b) When the inlet valve 7 or outlet valve 10 of the adsorption tower malfunctions, the pressure of the product gas will drop rapidly due to the low pressure of the adsorption tower 2. The pressure of the adsorption tower 2 will also rise rapidly, and the pressure of the adsorption tower 2 will rise again after a short period of time.

[0108] c) When the equalization valve 12 of the adsorption tower malfunctions, the pressure of adsorption tower 2 will not increase, or will increase very slowly, while the pressure of the equalization adsorption tower 2 will decrease rapidly.

[0109] Automatic tower switching judgment method:

[0110] When ΔP 实际 >ΔP 设定 If the pressure value that should be increased or decreased in adsorption tower 2 is not reached, a pressure alarm will be triggered. At the same time, if any valve in this tower malfunctions and alarms, the program will automatically shut down this tower.

[0111] (3) Other equalization processes (second equalization, third equalization, fourth equalization), forward release, reverse release, and final lifting processes

[0112] The other pressure equalization, forward discharge, reverse discharge, and final rise processes are basically the same as the tower cutting method in the first equalization process. When a valve malfunctions, it will have a certain impact on the pressure of adsorption tower 2. The difference lies in the fact that when ΔP 实际 <ΔP 设定 If a valve alarm is triggered, the program will automatically disconnect the faulty tower.

[0113] (4) Rinsing process

[0114] The main opening and closing actions of the control valves corresponding to adsorption tower 2 in the rinsing process are: opening the adsorption tower rinsing inlet valve 13, opening the adsorption tower rinsing exhaust valve 8, and closing the adsorption tower backflow valve 9.

[0115] Fault Analysis:

[0116] a) When the inlet valve 13 of the adsorption tower is faulty, the pressure of adsorption tower 2 will decrease. However, since the pressure of adsorption tower 2 itself is already very close to the desorption gas pressure (the pressure at the end of reverse discharge is about 0.05 MPa), the pressure of adsorption tower 2 will not decrease significantly. If one forward discharge gas tank is used to flush one adsorption tower 2, the pressure will rise rapidly after flushing the regulating valve 16, and the pressure of the forward discharge gas tank will not decrease.

[0117] b) When the adsorption tower flushing exhaust valve 8 malfunctions, the pressure in adsorption tower 2 will increase, which is equivalent to equalizing the pressure in the Heshun exhaust tank;

[0118] c) When the backflow valve 9 of the adsorption tower malfunctions, initially, since adsorption tower 2 has already completed its backflow, the pressure is around 0.05 MPa, while the pressure of other adsorption towers 2 undergoing backflow is around 0.2 MPa. At this time, both the backflow regulating valve 20 and the flushing regulating valve 16 are at a small opening. Therefore, the backflow gas from adsorption tower 2 in the backflow state will enter adsorption tower 2 through the backflow main pipe, causing the pressure of adsorption tower 2 to rise. As the operating time increases, the opening of the backflow regulating valve 20 and the flushing regulating valve 16 gradually increases, and eventually the pressure of adsorption tower 2 will also decrease. However, the desorption effect will be affected to some extent, and the desorption gas flow rate will also fluctuate greatly, thus affecting the temperature of the converter.

[0119] Automatic tower switching judgment method:

[0120] a) When ΔP 实际 >ΔP 设定 If a pressure alarm occurs, and at the same time any valve in this tower malfunctions (mainly check the adsorption tower flushing exhaust valve 8), the program will automatically shut down this tower.

[0121] b) When the flushing regulating valve 16, ΔP 实际 >ΔP 设定 If the flushing inlet valve 13 of the adsorption tower malfunctions, the program will automatically shut down the tower.

[0122] In some embodiments, after the tower is cut off, in order to restore the adsorption tower 2 to operation after the fault is resolved, the program will automatically select an appropriate step sequence to restore the adsorption tower 2 according to the pressure value of the cut-off adsorption tower 2. Since sometimes it may be difficult to find a suitable step sequence when the pressure is high, after the automatic tower is cut off, the fault is dealt with first, and then the pressure in the faulty tower is reduced to near the pressure value of the adsorption tower 2 in the reverse release process to realize the restoration after the tower is cut off. In this way, the pressure fluctuation of the entire system is minimized when the adsorption tower 2 is restored and the reverse release process is performed.

[0123] The automatic adjustment of the regulating valves is achieved by adjusting the lower limit of the valve opening value corresponding to the pressurization process, the reverse discharge process, and the flushing process in real time according to the changes in the load of the device.

[0124] Specifically, as the load on the device changes, the speeds of final lifting, reverse discharge, and flushing also change accordingly. Therefore, a slight adjustment to the lower limit of the opening value is required for more stable operation.

[0125] Among them, the regulating valves related to the pressurization process include the adsorption tower equalization / final pressurization regulating valve 15. The calculation method for the lower limit of the opening value of the adsorption tower equalization / final pressurization regulating valve 15 is as follows:

[0126] E1_L=(K1*F1) / (K T *K)+K2-K4;

[0127] The regulating valves related to the reverse discharge process include the reverse discharge regulating valve 20 and the pressure regulating valve after the reverse discharge gas buffer tank 4. The calculation method for the lower limit of the opening value of the reverse discharge regulating valve 20 is as follows:

[0128] D_L = (K5*F1) / (K2*K) + K6;

[0129] The calculation method for the lower limit of the opening value of the pressure regulating valve after the reverse venting buffer tank 4 is as follows:

[0130] N_L = (K9*F1) / (K2*K) + K10;

[0131] The regulating valve corresponding to the rinsing process includes a rinsing regulating valve 16. The calculation method for the lower limit of the opening value of the rinsing regulating valve 16 is as follows:

[0132] PP_L = (K7*F1) / (K2*K) + K8;

[0133] Where K is the flow rate (unit: Nm3 / H) corresponding to a 1.0% change in valve output, i.e., assuming K1 = 1 and K T When the value is 1, for every X times increase in the raw material gas, the valve flow rate increases by X%.

[0134] K1, K5, K7, and K9 are flow correction coefficients; KT is the time coefficient; K2, K4, K6, K8, and K10 are valve output fine-tuning values; and F1 is the average flow rate of the raw gas over one cycle.

[0135] The automatic adjustment of the desorption gas is achieved by calculating the set pressure of the desorption gas buffer tank based on the unit load, the pressure value of the reverse gas buffer tank 4 at the end of the reverse gas release process, and the amount of reverse gas stored in the reverse gas buffer tank 4, so that the desorption gas is delivered to the converter according to the calculated set pressure.

[0136] In some embodiments, to enable rapid adjustment of the stripper gas pressure regulation in response to load changes, stripper gas pressure control is divided into local and remote modes. In local mode, a single-loop regulation is used, where the operator sets a pressure value to maintain the stripper gas pressure to the converter around this value. The setpoint is not adjusted according to the unit's load and can only be manually entered by the operator. In remote mode, the set pressure is automatically adjusted according to the unit's load, using the following adjustment method:

[0137]

[0138] Wherein, N1 is the amount of reverse venting stored in the reverse venting buffer tank 4; N2 is the actual pressure value of the reverse venting buffer tank 4 at the end of the reverse venting process; N3 is the ideal pressure value of the reverse venting buffer tank 4 at the end of the reverse venting process; N4 is the adjustment coefficient; T A SP1 represents the adsorption cycle time; SP1 is the SP value of the previous cycle.

[0139] In other embodiments, the automatic control method also includes automatic pressure adjustment of the backflow buffer tank 4. Since backflow and flushing start simultaneously, there will be a large amount of desorption gas in the initial stage, which has a significant impact on the desorption gas pressure regulating valve 21. Therefore, this regulating loop is changed to the following control scheme: within T seconds after the start of the backflow process, the desorption gas pressure regulating valve 21 is in manual mode and opened to the lower limit of its opening value; after T seconds after the start of the backflow process, the desorption gas pressure regulating valve 21 is in automatic control mode and automatically adjusts its opening according to the desorption gas pressure set value, so that the desorption gas pressure is in a stable state (the deviation between the maximum and minimum values ​​can be controlled within 0.002 MPa).

[0140] In other embodiments, the automatic control method also includes automatic switching of regulating valves. Specifically, during normal production, if a regular regulating valve malfunctions, it can be controlled by opening a certain degree through a bypass. However, the equalization / final rise regulating valve 15, the reverse discharge regulating valve 20, and the flushing regulating valve 16 of the adsorption tower are automatically controlled by a program and are constantly changing. If a valve malfunctions and is manually fixed at a certain opening, it will greatly affect the stability of the device and the desorption effect of the adsorbent. Therefore, a backup valve is added to each of these three types of valves, and a valve opening feedback detection signal is added. If a running regulating valve malfunctions, the program automatically determines and switches to the backup valve, and an alarm appears on the operation screen to prompt the operator to perform timely maintenance.

[0141] For the equalization / final rise regulating valve 15 of the adsorption tower, during the final rise process, when the output value OP of the equalization / final rise regulating valve 15 of the adsorption tower is greater than OP... 设定When the operator inputs the signal, if the valve opening signal is not displayed and the pressure of adsorption tower 2 in the final lifting state does not change (i.e., ΔP), 实际 <ΔP 设定 If the valve opening signal is present and the pressure of adsorption tower 2 reaches or exceeds the end pressure of the first homogenization process (operator setting) within a short time, the valve closing signal is determined to be faulty, and the program should automatically switch to the standby valve.

[0142] For the reverse discharge control valve 20, during the reverse discharge process, when the output value OP of the control valve > OP 设定 If the valve opening signal of the regulating valve is not displayed, and the pressure of adsorption tower 2 does not change (i.e., ΔP), then... 实际 <ΔP 设定 If the valve output value is OP, it is determined that the valve is faulty, and the program automatically switches to the standby valve; when the output value of the regulating valve is OP... <OP 设定 If the valve opening signal is present and the pressure in adsorption tower 2 decreases rapidly (i.e., ΔP), then... 实际 >ΔP 设定 If the valve fails to close, the program will automatically switch to the backup valve.

[0143] For flushing control valve 16, during the flushing process, when the output value of the control valve OP > OP 设定 If the valve opening signal is not displayed and the pressure in the release tank does not change (i.e., ΔP), then... 实际 <ΔP 设定 If the flushing control valve 16 is faulty, the program will automatically switch to the standby valve; when the output value of the control valve is OP... <OP 设定 If the valve opening signal of the regulating valve is present, and the pressure in the venting tank decreases rapidly (i.e., ΔP), then... 实际 >ΔP 设定 If the valve fails to open, the program will automatically switch to the backup valve.

[0144] In this specification, the illustrative expressions of the terms used do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0145] Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention shall be included within the scope of protection of this invention.

Claims

1. An automatic control method for a pressure swing adsorption (PSA) process, the PSA process comprising an adsorption step, a depressurization step, a forward discharge step, a reverse discharge step, a rinsing step, and a pressurization step, characterized in that, include: Automatic adjustment of adsorption time: The adsorption time is calculated based on the device load, and the duration of the adsorption process is controlled by the calculated adsorption time. Automatic tower cut-off: Identify the control valve corresponding to the adsorption tower in the current process. When the actual pressure deviation in the adsorption tower does not meet the set pressure deviation requirement and the control valve corresponding to the adsorption tower in the current process has a fault alarm, the adsorption tower is determined to be a faulty tower and the faulty tower is cut off. Automatic adjustment of regulating valves: Based on changes in the unit load, the lower limit of the opening value of the regulating valves corresponding to the pressurization process, the reverse discharge process, and the flushing process is adjusted in real time; Automatic adjustment of desorption gas: The set pressure of the desorption gas buffer tank is calculated based on the unit load, the pressure value of the desorption gas buffer tank at the end of the desorption process, and the amount of desorption gas stored in the desorption gas buffer tank, so that the desorption gas is delivered to the converter according to the calculated set pressure. In the automatic adjustment and control valves, the control valves related to the pressurization process include the adsorption tower equalization / final pressurization control valve. The calculation method for the lower limit of the opening value of the adsorption tower equalization / final pressurization control valve is as follows: E1_L = (K1*F1) / (KT*K)+K2-K4; The regulating valves related to the reverse discharge process include the reverse discharge regulating valve and the pressure regulating valve after the reverse discharge gas buffer tank. The calculation method for the lower limit of the opening value of the reverse discharge regulating valve is as follows: D_L=(K5*F1) / (K2*K)+K6; The calculation method for the lower limit of the opening value of the pressure regulating valve after the reverse venting buffer tank is as follows: N_L=(K9*F1) / (K2*K)+K10; The regulating valves corresponding to the rinsing process include rinsing regulating valves. The calculation method for the lower limit of the opening value of the rinsing regulating valve is as follows: PP_L=(K7*F1) / (K2*K)+K8; Where K is the flow rate corresponding to a 1.0% change in valve output; K1, K5, K7, and K9 are flow rate correction coefficients; KT is the time coefficient; and K2, K4, K6, K8, and K10 are valve output fine-tuning values. F1 is the average flow rate of the raw gas over one cycle.

2. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, The method for calculating the adsorption time based on the device load is as follows: Among them, T 实际 T represents the current adsorption time. 设计 The adsorption time corresponding to the full load of the feed gas in the process design; F 设计 The full-load flow rate of the feed gas designed for the process; F 实际 K represents the average flow rate of the feed gas over one adsorption cycle. T This is the time coefficient.

3. The automatic control method for pressure swing adsorption process according to claim 2, characterized in that, Automatic adsorption time adjustment also includes adjusting the time coefficient based on the quality of the product gas.

4. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, The method for calculating the actual pressure deviation is as follows: when the adsorption tower enters another process from one process, the pressure value P1 inside the adsorption tower is obtained. Every time interval, the pressure value inside the adsorption tower is taken as P2. The actual pressure deviation ΔP_actual = |P2 - P1|. The set pressure deviation is the alarm pressure deviation value set for each process based on the actual operating conditions; When the actual pressure deviation is greater than or less than the set pressure deviation, the adsorption tower will trigger a pressure alarm.

5. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, The control valves corresponding to the adsorption tower in the adsorption process include: adsorption tower inlet valve, adsorption tower exhaust valve, and adsorption tower equalization / final rise valve. The control valves corresponding to the adsorption tower in the pressure reduction and pressure boosting processes include: adsorption tower inlet valve, adsorption tower exhaust valve, adsorption tower first equalization / final boost valve, and adsorption tower second equalization / third equalization valve. The control valves corresponding to the adsorption tower in the rinsing process include: adsorption tower rinsing inlet valve, adsorption tower rinsing exhaust valve, and adsorption tower backflow valve.

6. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, After automatic tower switching, the fault is first dealt with, and then the pressure in the faulty tower is reduced to the pressure value of the adsorption tower in the reverse release process. The reverse release process is then executed to achieve recovery after tower switching.

7. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, The calculation method for the set pressure of the desorption gas buffer tank is as follows: ； Wherein, N1 is the amount of reverse venting stored in the reverse venting buffer tank; N2 is the actual pressure value of the reverse venting buffer tank at the end of the reverse venting process; N3 is the ideal pressure value of the reverse venting buffer tank at the end of the reverse venting process; N4 is the adjustment coefficient; TA is the adsorption cycle time; and SP1 is the SP value of the previous cycle.

8. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, Also includes: Automatic pressure adjustment of the reverse venting buffer tank: Within T seconds of the start of the reverse venting process, the desorption gas pressure regulating valve opens to the lower limit of its opening value. After T seconds of the start of the reverse venting process, the opening of the desorption gas pressure regulating valve is automatically adjusted according to the desorption gas pressure setting value.

9. The automatic control method for pressure swing adsorption process according to claim 1, characterized in that, Also includes: Automatic switching of regulating valves: Backup valves are added to the equalization / final rise regulating valve, reverse discharge regulating valve and flushing regulating valve of the adsorption tower. When the output value of the regulating valve does not meet the set value requirement, the valve is judged to be faulty based on the valve opening signal and whether the actual pressure deviation in the adsorption tower meets the set pressure deviation requirement. When the regulating valve is faulty, it is switched to the corresponding backup valve.

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