Follow-up control method for multi-tower feeding pressure swing adsorption system

Abstract

The invention discloses a follow-up control method for a multi-tower feeding pressure swing adsorption system, and belongs to the technical field of pressure swing adsorption. According to the follow-up control method for the multi-tower feeding pressure swing adsorption system, the number of adsorption towers in a feeding adsorption state is m at any operation moment; each sub-cycle comprises n process steps which are carried out in sequence; one specified step in the Pth step is a time-adjustable step, and the operation duration is tx seconds; and calculating the sub-cycle time when running to the last second of the (P-1) th step, and assigning a value to tx, thereby adjusting the running time of the sub-cycle. According to the method, the feeding quantity and the operation sub-periods of the adsorption tower are accurately calculated in all the feeding sub-periods, and the variable time length step is set at the tail of the sub-periods, so that when the time of the sub-periods is calculated, the flow of other sub-periods is comprehensively considered, and the full space-time information of the flow in the operation sub-periods is fully considered; and the timeliness and the accuracy of adjustment are obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of pressure swing adsorption technology, specifically relating to a follow-up control method for a multi-tower feed pressure swing adsorption system. Background Technology

[0002] Since its first industrial application in the 1960s, Pressure Swing Adsorption (PSA) technology has undergone years of development and improvement, becoming one of the important processes in the field of gas separation and purification. This technology is based on the differences in the selective adsorption of different components in a mixed gas by the adsorbent under varying pressure conditions, achieving efficient separation of the target gas. With technological advancements, PSA plants have been continuously expanded in scale and operating pressures have been gradually increased. Its role has evolved from an auxiliary link in the production process to a key process unit, and it is widely used in various fields such as hydrogen purification, air separation for oxygen production, carbon dioxide capture, and natural gas purification.

[0003] As PSA technology continues to be promoted and deepened, the optimization of process flow and control systems has received increasing attention, especially in terms of auxiliary process improvement and control stability, where some progress has been made. However, in actual operation, key parameters such as the flow rate, composition, pressure, and temperature of the feed gas often fluctuate, directly affecting the purity and yield of the product gas. To ensure stable product indicators and achieve optimal recovery rates, how to adjust the adsorption time in real time and automatically according to changes in feed conditions has become a core challenge in the automatic control of PSA units.

[0004] Current common control methods typically adjust the adsorption time based solely on the feed gas flow rate of the previous single cycle, resulting in a relatively simple control model. This method struggles to accurately reflect the combined impact of dynamic changes in the flow rate of each tower on the adsorption process under conditions of multiple towers operating in parallel or sequential feeding. Furthermore, it fails to effectively characterize the cumulative flow effect and hysteresis characteristics between cycles during operation. Therefore, existing control strategies often lead to insufficient accuracy in adjusting the adsorption time when dealing with fluctuations in actual operating conditions, hindering the stable operation and energy efficiency optimization of PSA units under varying load conditions.

[0005] Therefore, a method and system for adaptive control of adsorption time suitable for multi-tower pressure swing adsorption processes is needed. This method and system features dynamic response to changes in feed gas parameters and integrates multi-cycle flow characteristics with multi-tower collaborative control mechanisms. This addresses the problems of inaccurate adsorption time adjustment and weak adaptability to operating conditions caused by the simplification of control models in existing technologies, and has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a follow-up control method for a multi-tower feed pressure swing adsorption system. This method adjusts the operating cycle time by using flow rate data from multiple cycles and the flow rate data of each operating cycle, and corrects the cycle time based on the quality of the product gas and the adsorption phase content of the feed gas. This allows the cycle time to be dynamically adjusted according to changes in the feed gas flow rate, composition, and product gas quality, thereby achieving precise control of the pressure swing adsorption system.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention discloses a follow-up control method for a multi-tower feed pressure swing adsorption system. The timing characteristics of the method are defined by the following parameters: at any operating time, the number of adsorption towers in the feed adsorption state is m (m ≥ 1, an integer); each adsorption tower's cycle contains n sequentially performed process steps; wherein, a designated step at step P is a time-adjustable step with a running time of tx seconds; when running to the last 1 second of step P-1, the cycle time is calculated and tx is assigned a value, thereby adjusting the running time of this cycle.

[0008] tx is calculated according to formula (1): Formula (1) In formula (1), k1 is the flow rate adjustment coefficient, with a value ranging from 0.5 to 1.5. F0 represents the design flow rate, in Nm³. 3 / h T0 is the design cycle time, in seconds. F -1 The average flow rate of the previous cycle, in Nm³. 3 / h, T -1 The previous period's time, in seconds. F -2 The average flow rate for the first two cycles, in Nm³. 3 / h, T -2 The time for the first two periods is in seconds. F -m+1 The average flow rate for the first (m-1) cycles, in Nm³. 3 / h, T -m+1 The first (m-1) periodic times, in seconds. F1 is the average flow rate over the operating cycle, which is the average flow rate from step P of the previous cycle to the time of flow calculation at step P-1 of the operating cycle, in Nm³. 3 / h, t1 is the time for the first step of the cycle, in seconds. t2 is the time for the second step of the cycle, in seconds. t p-1 The time for the P-1th step of the cycle is expressed in seconds. t p+1 The time for the (P+1)th step of the cycle is expressed in seconds. t n The time taken to run the nth step of the cycle, in seconds.

[0009] When m=1, tx is calculated according to formula (2): Formula (2); In formula (2) k1, F0, F1, T0, t1, t2, t p-1 t p+1 t n The definition is the same as in formula (1).

[0010] In some embodiments of the present invention, based on the influence of product gas quality on cycle time, a feedback coefficient k2 is added for dynamic adjustment based on product gas quality, which is used to correct tx; The initial value of the feedback coefficient k2 is 0 seconds; tx is calculated according to formula (3): Formula (3) In formula (3), k1, F0, F1, F -1 F -2 F -m+1 T0, T -1 T -2 T -m+1 t1, t2, t p-1 t p+1 t n The definition of m is the same as that in formula (1); The feedback coefficient k2 is updated in each operating cycle, and its value is the sum of the k2 value of the previous cycle and the adjustment value calculated based on the current product gas quality deviation.

[0011] In some embodiments of the present invention, in formula (3), if the non-adsorbed phase is used as the product gas, the feedback coefficient k2 is dynamically adjusted according to the deviation between the product gas quality and the design value: When the product gas quality exceeds the upper limit threshold of the design value, the calculated value of k2 is 1 second, that is, k2 is increased by 1 second on the basis of the previous cycle as the k2 of the running cycle; When the product gas quality is lower than the lower limit threshold of the design value, the calculated value of k2 is -3 seconds, that is, k2 is reduced by 3 seconds from the previous cycle to get the k2 of the operating cycle.

[0012] If the non-adsorbed phase is used as the product gas, and the purity of the target product component is significantly affected by the content of a certain key impurity component, and the two have a coupled relationship in controlling product quality, then a feedback coefficient k corresponding to the purity of the target product should be set separately. p The feedback coefficient k corresponding to the impurity content i The smaller of the two values ​​is taken as the calculated value of the system's feedback coefficient, i.e., k2 = min{k p k i This ensures that product quality meets both purity and impurity limits.

[0013] In some embodiments of the present invention, the product is H2, and its quality is affected by the coupling effect of H2 purity and CO content. Therefore, the corresponding feedback coefficient k is calculated based on the online analysis results of H2 and CO in the product gas, respectively. H2 and k CO The smaller of the two values ​​is taken as the feedback coefficient for product gas quality, i.e.: k2=min{k H2 k CO}

[0014] Hydrogen feedback coefficient k H2 Determine as follows: (1) If the hydrogen purity of the product is found to be below the design requirement, the adsorption time needs to be shortened to enhance regeneration. Therefore, let k be the value of the hydrogen. H2 = 3 seconds; (2) The purity of the product hydrogen is at the lower limit of the design, but still acceptable. A conservative control is adopted, and k is set. H2 = 1 second.

[0015] (3) The purity of hydrogen in the product is better than the design requirements, and the trend of change needs to be considered. 偏-H2 Further analysis reveals that A... 偏-H2 = Previous period H2 sample value - Current period H2 sample value: (31) If A 偏-H2 < A purity increase of 0.02% (i.e., a significant increase in purity compared to the previous cycle) indicates improved adsorption performance, suggesting that the adsorption time can be appropriately extended, and k can be set. H2 =+1 second; (32) If A 偏-H2 >+0.02% (meaning a significant decrease in purity compared to the previous cycle), although currently still within the acceptable range, there is a deteriorating trend requiring early intervention. A k-value should be set. H2 = 1 second; (33) If A 偏-H2 ≤0.02%, set k H2 =0 seconds.

[0016] (34) If the purity of the hydrogen in the product is significantly better than the design value and the system has sufficient operating margin, the adsorption time can be appropriately extended to improve the hydrogen recovery rate. Set k H2 =+2 seconds.

[0017] CO feedback coefficient k CO Determine as follows: (1) The CO content is far below the design limit and the purification effect is good. The adsorption time can be extended to improve efficiency. Set k CO =+2 seconds; (2) The CO content is within the safe range and there is no obvious risk. Set k CO =0 seconds.

[0018] (3) The CO content is close to the threshold for exceeding the standard, and it needs to be considered in conjunction with the trend of change. 偏-CO Judgment: A 偏-CO = Previous period CO sample value - Current period CO sample value: (31) Only if A 偏-CO A concentration of less than -0.5 ppm indicates a significant increase in CO content compared to the previous cycle, showing a clear deterioration trend and triggering enhanced regeneration measures. A k-value is then set. CO = 2 seconds; (32) If the CO content is high, but shows a decreasing or stable trend (A) 偏-CO ≥-0.5ppm), set k CO =0 seconds.

[0019] (4) If the CO content has reached or exceeded the design limit, the product is unqualified. The adsorption time must be shortened immediately, desorption and regeneration must be strengthened, and k must be set. CO = 3 seconds.

[0020] In some embodiments of the present invention, in formula (3), if the adsorbed phase is used as the product gas, the parameter k2 is dynamically adjusted according to the deviation between the product gas quality and the design value: If the product gas quality is too high, exceeding the upper limit threshold of the design value, the calculated value of k2 is -1 second, that is, k2 is reduced by 1 second based on the previous cycle as the k2 of the operating cycle; If the product gas quality is too low, below the lower limit threshold of the design value, the calculated value of k2 is 3 seconds, that is, k2 is increased by 3 seconds on the basis of the previous cycle as the k2 of the operating cycle.

[0021] In some embodiments of the present invention, feedforward revision of the feed gas composition is introduced considering changes in the feed gas composition, and the revised tx is calculated according to formula (4): Formula (4) In formula (4), Y0 is the content of the designed adsorbent phase, in mol / mol. Y -1 The average content of the adsorbed phase in the previous cycle, in mol / mol; Y -2 The average flow rate for the first two cycles is expressed in mol / mol. Y -m+1 The average content of the adsorbed phase in the first (m-1) periodic phases is expressed in mol / mol. Y1 represents the average content of the adsorbed phase during the cycle calculation time (i.e., from step P of the previous cycle to the flow calculation time of step P-1 of the cycle), in mol / mol.

[0022] k1, F0, F1, F -1 F -2 F -m+1 T0, T -1 T -2 T -m+1 t1, t2, t p-1 t p+1 t n The definitions of m and k2 are the same as in formula (1), and the definition of k2 is the same as in formula (3).

[0023] Compared with the prior art, the present invention has the following beneficial effects: This invention is scientifically designed and ingeniously conceived. By precisely calculating the feed rate and operating cycle of the adsorption tower in all feeding cycles, and setting the variable-duration step at the end of each cycle, the calculation of cycle time not only comprehensively considers the flow rates of other cycles but also fully takes into account the spatiotemporal information of the flow rates within the operating cycle, significantly improving the timeliness and accuracy of regulation. Furthermore, this invention further refines the control model by introducing feedforward parameters of product gas quality feedback coefficient and feed gas adsorption phase content, enhancing the flexibility and adaptability of the control process. Attached Figure Description

[0024] Appendix Figure 1 This is a flowchart of Embodiment 1 of the present invention; Appendix Figure 2 This is a partial timing diagram of the hydrogen extraction process using 12 towers; Appendix Figure 3 This is a flowchart of Embodiment 2 of the present invention; Appendix Figure 4 This is a partial timing diagram of the carbon dioxide purification process using 10 towers. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] The present invention will be described in detail below through specific examples, but should not be construed as the subject matter of the present invention.

[0027] Example 1 This embodiment discloses a follow-up control method for a multi-tower feed pressure swing adsorption (PSA) system. The PSA process is a 12-tower hydrogen purification process, employing simultaneous feeding of 3 towers, 5-stage pressure equalization, and rinsing operations. Its overall process flow is as follows: Figure 1 As shown.

[0028] In this embodiment, the system is equipped with a raw gas flow meter and an online hydrogen analyzer at the raw gas inlet; and a hydrogen purity analyzer and a trace carbon monoxide (CO) analyzer are provided at the product gas outlet.

[0029] Raw material gas operating pressure: 2.9 MPaG; Design feed gas flow rate: 150,000 Nm 3 / h; Design cycle time: 60 seconds; Design composition of feed gas (volume ratio): H2:Ar:N2:CO:CH4 = 93:0.2:0.8:5.9:0.1; Designed product hydrogen purity: ≥99.9% (vol); The CO content in the product gas should be ≤10ppm (vol). Desorption operation pressure: 0.02 MPaG.

[0030] In this embodiment, the core of the follow-up control lies in dynamically adjusting the duration of the last step of each sub-cycle. tx This allows for real-time adaptation to fluctuations in raw material gas conditions and changes in product gas quality. Figure 2 Three cycle-based timing sequences for implementing multi-tower feed follow-up control are presented. Each cycle contains seven process steps, with durations t1, t2, t3, t4, t5, t6, and tx (in seconds). tx is the only variable parameter, dynamically updated based on real-time operating conditions. The follow-up control method is illustrated using the third cycle as an example: Update timing: One second before the end of step 6 in each sub-cycle, calculate and update the next cycle based on the current operating conditions. tx value.

[0031] 1. Basic calculation formula: The initial value of tx is determined by formula (5): Formula (5) Where k1 is the flow rate adjustment coefficient, and the initial value of k1 is 1.05; F0 is the design flow rate, 150,000 Nm. 3 / h; T0 is the design cycle time, 60 seconds; F2 is the average flow rate during the second cycle of the device's operation (average flow rate during the second cycle). T2 is the second cycle time during device operation; F1 is the average flow rate during the first cycle of the device's operation (average flow rate during the first cycle). T1 is the first cycle time during device operation; F3 represents the average flow rate over the operating cycle, specifically the average flow rate from step 7 of the second cycle to step 6 of the third cycle (1 second before the end). t1, t2, t3, t4, t5, and t6 are the times for the first to sixth steps of the cycle, which are 2 seconds, 10 seconds, 12 seconds, 2 seconds, 10 seconds, and 12 seconds, respectively.

[0032] 2. Product gas quality feedback mechanism To improve the stability of product gas quality, a product gas quality feedback coefficient k2 is introduced to correct the formula (1), that is: tx = formula (5) + k2, specifically: Formula (6) The feedback coefficient k2 is the sum of the calculated values ​​of k2 in the second and third periods. The calculated value of the feedback coefficient is dynamically adjusted based on the online analysis results of H2 purity and CO content in the product gas, taking into account the correlation between the two.

[0033] Specifically, the definition is: k H2 Feedback coefficients based on H2 purity analysis; k CO Feedback coefficient based on CO content analysis; Since H2 purity and CO content have a coupled effect, the smaller of the two values ​​is ultimately used as the calculated feedback coefficient: k2=min{k H2 k CO}

[0034] Sampling by all online analyzers is completed 1 second before the end of step 6 of each cycle.

[0035] (1) H2 purity feedback rule set up: A 0-H2 H2 purity sampled value (%) for this period A 1-H2 H2 purity sampled value (%) in the previous cycle A 偏-H2 =A 1-H2 A 0-H2 Change in H2 purity between adjacent periods According to A0 and A 偏 The combination of k is determined according to Table 1. H2 : Table 1

[0036] Note: When A 0-H2 When in interval 3 or 4, trend A needs to be considered. 偏-H2 Determine whether the quality is improving or deteriorating, and then decide whether to increase or decrease tx.

[0037] (2) CO content feedback rules set up: A 0-CO CO purity sample value (ppm) for this period. A 1-CO CO purity sample value (ppm) from the previous cycle. A 偏-CO =A 1-CO A 0-CO Changes in CO content between adjacent periods According to A0 and A 偏 The combination of k is determined according to Table 1. CO : Table 2

[0038] Note: The lower the CO content, the more likely it is to decrease (A) 偏-CO <0 indicates good adsorption effect, and tx can be appropriately extended (positive adjustment); otherwise, tx needs to be shortened to enhance regeneration.

[0039] 3. Feedforward compensation of feedstock gas components Considering the direct impact of feed gas composition fluctuations on adsorption performance, a feed gas composition feedforward correction term is further introduced based on the aforementioned feedback control. The revised tx calculation formula is as follows: Formula (7) Where H0 is the design value of hydrogen content in the feed gas (0.93), H2 is the average hydrogen content in the feed gas in the second cycle, H1 is the average hydrogen content in the feed gas in the first cycle, and H3 is the average hydrogen content in the feed gas during the cycle calculation time (i.e., from the 7th step of the second cycle to the 6th step of the third cycle when the flow rate is calculated).

[0040] This embodiment employs a three-layer control architecture of "basic timing + product quality feedback + feedstock composition feedforward," comprehensively considering the flow rate and feedstock composition changes across three cycles to achieve dynamic adjustment of the cycle time of the multi-tower PSA system. This method effectively improves the stability of product hydrogen purity and impurity control under fluctuating feedstock conditions, while also considering unit operating efficiency and energy consumption optimization. In contrast, traditional control methods only consider the flow rate data of the previous cycle, resulting in poor accuracy and timeliness of the control strategy.

[0041] Example 2 This embodiment discloses a follow-up control method for a multi-tower feed pressure swing adsorption (PSA) system. The PSA process employs a 10-tower flow for carbon dioxide purification, specifically a 4-tower simultaneous feed, 2-step pressure equalization, and vacuum desorption operation mode. Its process flow diagram is shown below. Figure 2 As shown.

[0042] A feed gas flow meter and an online carbon dioxide analyzer are installed at the feed gas inlet for real-time monitoring of feed conditions. The system design parameters are as follows: Raw material gas pressure: 0.4 MPaG The designed feed gas flow rate is 20000 Nm. 3 / h, Design cycle time: 60 seconds. The designed feed gas composition (volume ratio) is: H2:CO2:CO:CH4 = 2.4:77.9:0.7:19. Product CO2 purity requirement: ≥95%.

[0043] In this embodiment, the multi-tower feeding follow-up control strategy is implemented through four sub-cycles, and its timing arrangement is as follows: Figure 4 As shown. Each cycle consists of 7 steps, with durations of t1, t2, t3, tx, t5, t6, and t7 (in seconds). The key variable tx is dynamically adjusted based on the feed gas conditions.

[0044] Taking the fourth cycle as an example, the specific implementation method of servo control is explained: tx update timing: In the last second before the end of step 3, the system calculates and updates the value of tx in real time; 1. Basic calculation formula: tx is calculated according to formula (8); Formula (8) Where k1 is the flow adjustment coefficient with an initial value of 1.02, F0 is the design flow rate, T0 is the design cycle time, F1 is the average flow rate of the first cycle (average flow rate of the first cycle), T1 is the cycle time of the first cycle, F2 is the average flow rate of the second cycle (average flow rate of the second cycle), T2 is the cycle time of the second cycle, F3 is the average flow rate of the third cycle (average flow rate of the third cycle), T3 is the cycle time of the third cycle, F4 is the average flow rate of the running cycle, that is, the average flow rate from the fourth step of the third cycle to the third step of the fourth cycle (the last second), and t1, t2, t3, t5, t6, and t7 are the times of each step in the cycle, which are 2 seconds, 15 seconds, 15 seconds, 10 seconds, 10 seconds, and 2 seconds, respectively.

[0045] 2. Component feedforward correction: To address fluctuations in the composition of the feed gas, a component feedforward correction mechanism based on data from an online CO2 analyzer is introduced. The corrected tx is determined by formula (9).

[0046] Formula (9) Where C0 is the design value of carbon dioxide content in the feed gas (0.779), C1 is the average carbon dioxide content in the feed gas in the first cycle, C2 is the average carbon dioxide content in the feed gas in the second cycle, C3 is the average carbon dioxide content in the feed gas in the third cycle, and C4 is the average carbon dioxide content in the feed gas during the cycle calculation time (i.e., from the fourth step of the third cycle to the third step of the fourth cycle when the flow rate is calculated).

[0047] The follow-up control method in this embodiment can dynamically adjust the adsorption time in real time according to the changes in the flow rate and composition of the feed gas during the four cycles of adsorption tower operation, thereby stabilizing product purity and improving system operating efficiency. In contrast, traditional control methods only consider the flow rate data of the previous cycle, resulting in poor accuracy and timeliness of the control strategy.

[0048] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the scope of the patent. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but which still solve the same technical problem as the present invention, should be included within the scope of protection of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the scope of patent protection of the present invention.

Claims

1. A servo control method for a multi-tower feed pressure swing adsorption system, characterized in that, At any given time of operation, the number of adsorption towers in the feed adsorption state is m, where m is an integer ≥ 1; each cycle contains n sequential process steps; among them, a designated step at step P is a time-adjustable step with a runtime of tx seconds; when running to the last second of step P-1, the cycle time is calculated and tx is assigned a value, thereby adjusting the running time of this cycle. tx is calculated according to formula (1): Official (1) In formula (1), k1 is the flow rate adjustment coefficient, with a value ranging from 0.5 to 1.

5. F0 represents the design flow rate, in Nm³. 3 / h, T0 is the design cycle time, in seconds. F -1 The average flow rate of the previous cycle, in Nm³. 3 / h, T -1 The previous period's time, in seconds. F -2 The average flow rate for the first two cycles, in Nm³. 3 / h, T -2 The time for the first two periods is in seconds. F -m+1 The average flow rate for the first (m-1) cycles, in Nm³. 3 / h, T -m+1 The first (m-1) periodic times, in seconds. F1 is the average flow rate over the operating cycle, which is the average flow rate from step P of the previous cycle to the time of flow calculation at step P-1 of the operating cycle, in Nm³. 3 / h, t1 is the time for the first step of the cycle, in seconds. t2 is the time for the second step of the cycle, in seconds. t p-1 The time for the P-1th step of the cycle is expressed in seconds. t p+1 The time for the (P+1)th step of the cycle is expressed in seconds. t n The time taken to run the nth step of the cycle, in seconds.

2. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 1, characterized in that, When m=1, tx is calculated according to formula (2): Official (2); In formula (2) k1, F0, F1, T0, t1, t2, t p-1 t p+1 t n The definition is the same as in formula (1).

3. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 1 or 2, characterized in that, Based on the impact of product gas quality on cycle time, a feedback coefficient k2 is added for dynamic adjustment based on product gas quality to correct tx; The initial value of the feedback coefficient k2 is 0 seconds; tx is calculated according to formula (3): Official (3) In formula (3), k1, F0, F1, F -1 F -2 F -m+1 T0, T -1 T -2 T -m+1 t1, t2, t p-1 t p+1 t n The definitions of m and m are the same as in formula (1). The feedback coefficient k2 is updated in each operating cycle, and its value is the sum of the k2 value of the previous cycle and the adjustment value calculated based on the current product gas quality deviation.

4. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 3, characterized in that, In formula (3), if the non-adsorbed phase is used as the product gas, the feedback coefficient k2 is dynamically adjusted according to the deviation between the product gas quality and the design value: When the product gas quality exceeds the upper limit threshold of the design value, the calculated value of k2 is 1 second, that is, k2 is increased by 1 second on the basis of the previous cycle as the k2 of the running cycle; When the product gas quality is lower than the lower limit threshold of the design value, the calculated value of k2 is -3 seconds, that is, k2 is reduced by 3 seconds based on the previous cycle, and is used as the k2 of the operating cycle.

5. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 3, characterized in that, If the non-adsorbed phase is used as the product gas, and the purity of the target product component is significantly affected by the content of a certain key impurity component, and the two have a coupled relationship in controlling product quality, then a feedback coefficient k corresponding to the purity of the target product should be set separately. p The feedback coefficient k corresponding to the impurity content i The smaller of the two values ​​is taken as the calculated value of the system's feedback coefficient, i.e., k2 = min{k p k i } 6. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 5, characterized in that, The product is H2. The corresponding feedback coefficient k is calculated based on the online analysis results of H2 and CO in the product gas. H2 and k CO The smaller of the two values ​​is taken as the feedback coefficient for product gas quality, i.e.: k2=min{k H2 k CO } 7. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 6, characterized in that, Hydrogen feedback coefficient k H2 Determine as follows: (1) If the hydrogen purity of the product is found to be below the design requirement, set k H2 = 3 seconds; (2) The purity of the product hydrogen is at the lower limit of the design, and k is set. H2 = 1 second; (3) The purity of hydrogen in the product is better than the design requirements, and the trend of change needs to be considered. 偏-H2 Further judgment is needed; among them, A 偏-H2 = Previous period H2 sample value - Current period H2 sample value: (31) If A 偏-H2 < 0.02%, set k H2 =+1 second; (32) If A 偏-H2 >+0.02%, set k H2 = 1 second; (33) If A 偏-H2 ≤0.02%, set k H2 =0 seconds; (34) If the purity of hydrogen in the product is significantly better than the design value, set k H2 =+2 seconds.

8. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 6, characterized in that, CO feedback coefficient k CO Determine as follows: (1) The CO content is far below the design limit, so k is set. CO =+2 seconds; (2) The CO content is within the safe range, so k is set. CO =0 seconds; (3) The CO content is close to the threshold for exceeding the standard, and it needs to be considered in conjunction with the trend of change. 偏-CO Judgment: A 偏-CO = Previous period CO sample value - Current period CO sample value: (31) Only if A 偏-CO <-0.5ppm, set k CO = 2 seconds; (32) If the CO content is high but shows a decreasing or stable trend, set k CO =0 seconds; (4) If the CO content has reached or exceeded the design limit, set k CO = 3 seconds.

9. The follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 3, characterized in that, In formula (3), if the adsorbed phase is used as the product gas, the feedback coefficient k2 is dynamically adjusted according to the deviation between the product gas quality and the design value: If the product gas quality is too high, exceeding the upper limit threshold of the design value, the calculated value of k2 is -1 second, that is, k2 is reduced by 1 second based on the previous cycle as the k2 of the operating cycle; If the product gas quality is too low, below the lower limit of the design value, the calculated value of k2 is 3 seconds, that is, k2 is increased by 3 seconds on the basis of the previous cycle as the k2 of the operating cycle.

10. A follow-up control method for a multi-tower feed pressure swing adsorption system according to claim 3, characterized in that, Based on the changes in the composition of the feed gas, a feedforward revision of the feed gas composition is introduced, and the revised tx is calculated according to formula (4): Official (4) In formula (4), Y0 is the content of the designed adsorbent phase, in mol / mol. Y -1 The average content of the adsorbed phase in the previous cycle, in mol / mol; Y -2 The average flow rate for the first two cycles is expressed in mol / mol. Y -m+1 The average content of the adsorbed phase in the first (m-1) periodic phases is expressed in mol / mol. Y1 represents the average content of the adsorbed phase during the cycle calculation time (i.e., from step P of the previous cycle to the flow calculation time of step P-1 of the cycle), in mol / mol. k1, F0, F1, F -1 F -2 F -m+1 T0, T -1 T -2 T -m+1 t1, t2, t p-1 t p+1 t n The definitions of m and k2 are the same as in formula (1), and the definition of k2 is the same as in formula (3).

Images