On-line diagnosis control system and control method for pressure swing adsorption tower

Abstract

The invention relates to the technical field of hydrogen purification, in particular to an online diagnosis control system and method for a pressure swing adsorption tower. The control system comprises a product gas buffer tank used for storing the product gas of the pressure swing adsorption device; the main passage is connected with the product gas buffer tank and the analyzer and is used for conveying the product gas during normal detection; the multi-channel pipeline comprises a plurality of branch channels, and each branch channel is connected with one adsorption tower and is used for independently detecting the product gas of each adsorption tower; the automatic control unit is used for controlling opening and closing of valves of the main channel and the multi-channel pipeline to realize automatic switching of detection modes; and the analyzer is used for performing component analysis on the product gas. According to the invention, a multi-channel adsorption tower online diagnosis system is independently and additionally arranged on an original hydrogen detection pipeline. When a product quality problem occurs, the adsorption tower with the problem can be accurately positioned by virtue of the online diagnosis control system for the adsorption tower, so that the disposal cost is greatly reduced, and the problem solving efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen purification, and in particular to an online diagnosis control system and a control method for a pressure swing adsorption tower. Background Art

[0002] At present, most pressure swing adsorption devices use programmable valves to control hydrogen purification, but there are disadvantages such as valve body leakage and oil leakage. To solve these problems, the rPSA (rapid cycle pressure swing adsorption) process is used in the existing technology. This process uses a rotary valve control valve to avoid system internal leakage and oil leakage caused by frequent switching.

[0003] One set of adsorption device is equipped with one set of light valve and one set of heavy valve. When the specific area of ​​the rotary valve turns to each channel in turn, the corresponding adsorption tower immediately starts the adsorption process; once it turns away from the channel, the adsorption process stops and the adsorption tower enters the regeneration stage. By flexibly adjusting the speed of the rotary valve, the time spent on the adsorption, analysis and other processes of the entire pressure swing adsorption device can be accurately controlled.

[0004] There are many influencing factors inside the adsorption tower, such as uneven adsorbent filling effects, contamination of some adsorbents, and the presence of polar molecules in the adsorbent. These factors work together to cause significant differences in the purification efficiency of each adsorption tower.

[0005] At present, the time taken by each adsorption tower in the pressure swing adsorption device to purify hydrogen is between 60 seconds and 120 seconds. The existing multi-channel gas rapid online analysis system lacks the online diagnostic control capability of the pressure swing adsorption tower, and it is difficult to switch frequently to detect the purification effect of each adsorption tower in the pressure swing adsorption device. Therefore, it is urgent to detect the adsorbent filling status of the adsorption tower and implement targeted treatment of the adsorption tower according to different situations, so as to resolve the problem of poor overall purification effect of the pressure swing adsorption device. Summary of the invention

[0006] The present invention aims to overcome the shortcomings of the prior art and provides an online diagnostic control system and control method for a pressure swing adsorption tower, which can not only detect the mixed product gas of the pressure swing adsorption device, but also realize automatic control, detect the product gas of each adsorption tower, and automatically switch to the mode of checking each adsorption tower during operation.

[0007] The first aspect of the present invention provides an online diagnosis and control system for a pressure swing adsorption tower, comprising: Product gas buffer tank, used to store product gas from the pressure swing adsorption device; The main passage connects the product gas buffer tank and the analyzer and is used for product gas transportation during normal testing; A multi-channel pipeline includes a plurality of branch channels, each of which is connected to an adsorption tower and is used to individually detect the product gas of each adsorption tower; Automatic control unit, used to control the valve switches of the main channel and multi-channel pipelines to achieve automatic switching of detection modes; Analyzer, used to analyze the composition of product gas to evaluate the purification effect of the adsorption tower; The system also includes an outlet pressure transmitter, a multi-channel pressure transmitter, a pressure reducing valve, an injection system and an emptying system. The automatic control unit automatically identifies the purification or analysis process of the adsorption tower according to the change of the outlet pressure of the adsorption tower, and completes the channel pipeline replacement and sampling and injection actions.

[0008] Furthermore, the multi-channel pipeline comprises: Multi-channel sample cut-off valve, used to control the passage of product gas into the analyzer; Analytical injection valve, used to introduce product gas into the analyzer; Analytical injection pressure transmitter, used to detect injection pressure.

[0009] Furthermore, the emptying system comprises: Drain shut-off valve, used to control the discharge of gas in the pipeline; Flare valve, used to discharge gas to the flare system.

[0010] Furthermore, the automatic control unit comprises: A control logic module is used to automatically control the opening and closing of the valve according to pressure changes; The data processing module is used to process the detection data of the analyzer and evaluate the purification effect of the adsorption tower.

[0011] Further, the analyzer is connected to: Standard gas / sample three-way valve, used to switch the passages of standard gas and sample gas; Filter, used to filter impurities in product gas.

[0012] Furthermore, the system also includes a safety valve for preventing the system pressure from being too high.

[0013] The second aspect of the present invention provides a control method based on the pressure swing adsorption tower online diagnostic control system, comprising the following steps: S1. In normal detection mode, the automatic control unit opens the outlet shut-off valve of the main channel, closes all the shut-off valves of the multi-channel pipeline, and the product gas enters the analyzer through the main channel for detection; S2. In the diagnostic mode, the automatic control unit closes the outlet shut-off valve of the main channel, opens the shut-off valve of a branch channel of the multi-channel pipeline in turn, and uses the product gas of the adsorption tower to replace the gas in the branch channel; S3. When the pressure in the branch passage reaches the set value, the automatic control unit closes the shut-off valve of the branch passage, opens the exhaust shut-off valve, and exhausts the gas in the pipeline; S4. Repeat steps S2 and S3 to detect the product gas of each adsorption tower separately.

[0014] Furthermore, in step S1, the product gas passes through the outlet pressure transmitter and the multi-channel pressure transmitter and enters the analyzer for detection.

[0015] Furthermore, in step S2, the automatic control unit automatically identifies the purification or analysis process of the adsorption tower according to the change of the outlet pressure of the adsorption tower.

[0016] Furthermore, in step S3, the branch passage after being emptied reduces its pressure to a pressure range suitable for detection by the analyzer through a pressure reducing valve, and then enters the analyzer for detection.

[0017] The advantages and positive effects of the present invention are:

[0018] 1. The present invention independently adds a multi-channel adsorption tower online diagnostic system to the original hydrogen inspection pipeline. When there is a problem with product quality, the adsorption tower with the problem can be accurately located by means of the adsorption tower online diagnostic control system, and then targeted treatment can be carried out, which greatly reduces the treatment cost and improves the efficiency of problem solving.

[0019] 2. The present invention adopts an automatic control mode, which not only saves manpower and time costs, but also performs real-time detection of the entire life cycle of the adsorbent in the adsorption tower. Through advanced monitoring technology, it can issue early warnings for possible adsorbent contamination accidents, providing strong support for ensuring stable operation of the device and maintaining efficient purification effects.

[0020] 3. The present invention has an automatic setting operation function, which can realize an automated analysis and inspection process, effectively reduce the adverse effects caused by human operation errors, and significantly improve the accuracy and stability of analysis and inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of the online diagnosis control system of the pressure swing adsorption tower of the present invention.

[0022] Figure 2 This is a control logic diagram of the online diagnosis and control system of the pressure swing adsorption tower of the present invention.

[0023] Among them: 1- outlet pressure transmitter, 2- outlet cut-off valve, 3- multi-channel pressure transmitter, 4- multi-channel injection cut-off valve, 5- pressure reducing valve, 6- multi-channel injection valve, 7- analytical injection valve, 8- analytical injection pressure transmitter, 9- standard gas / sample three-way valve, 10- standard gas pipeline, 11- filter, 12- analyzer, 13- check valve, 14- analyzer flare valve, 15- safety valve, 16- drain cut-off valve, 17- drain valve, 18- flare valve, 19- safety valve flare valve. DETAILED DESCRIPTION

[0024] The present invention is described in detail below through specific embodiments. The adsorption tower online diagnosis system can be allocated with multiple pipelines, and two pipelines are listed this time. The embodiments are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited by them.

[0025] The online diagnosis and control system of the pressure swing adsorption tower of the present invention comprises a product gas buffer tank, a main passage, a multi-pass pipeline, an automatic control unit and an analyzer. In the normal detection mode, the main passage is opened, the multi-pass pipeline is closed, and the product gas enters the analyzer through the main passage for detection. In the diagnosis mode, the main passage is closed, the multi-pass pipeline is opened in sequence, and the product gas of each adsorption tower is detected separately.

[0026] like Figure 1 As shown, the adsorption tower product gas passes through the outlet pressure transmitter 1, the outlet cut-off valve 2, and the multi-channel pressure transmitter 3, and enters the multi-channel pipeline, and can be discharged to the flare system for replacement through the emptying cut-off valve 16 in the gas discharge pipeline. Since the adsorption tower and the analysis room and the analyzer 12 are far apart, it is possible to store gas in the multi-channel pipeline for subsequent gas analysis. Through the multi-channel injection cut-off valve 4, the gas is decompressed to below 0.2Mpa through the pressure reducing valve 5 before injection, and enters the analysis and inspection system through the multi-channel injection valve 6. In order to ensure that the pressure in this pipeline is below 0.2Mpa, a safety valve 15 is added to ensure that the system pressure does not exceed 0.2Mpa. If the pressure reducing valve fails and the analyzer 12 detection system exceeds 0.2Mpa, the safety valve 15 automatically opens to release the pressure to the flare system. After overpressure, the gas is discharged to the flare system through the safety valve 15 and the safety valve to the flare valve 19. After the sample passes through the analytical injection valve 7 and the analytical injection pressure transmitter 8, it is decompressed to 0.1Mpa through the standard gas / sample three-way valve 9, the filter 11, and the pressure reducing valve 5, and enters the analyzer 12 injection system, and is emptied into the flare system through the check valve 13 and the analyzer flare valve 14. The standard gas pipeline 10 is used for regular calibration of the analyzer 12. The drain valve 17 is a manual valve for the discharge outlet, which is generally open and only closed when stopping detection or maintenance. The flare valve 18 is a manual valve for draining the diagnostic system and is only closed during maintenance.

[0027] Control logic: The end of the product gas after purification by the adsorption tower can best reflect the adsorption tower's extraction capacity. Through the sampling and detection of the end gas of the product gas by the automatic control unit, the purification effect of each adsorption tower can be accurately diagnosed, and targeted treatment can be achieved. The adsorption tower purification or analysis process can be automatically identified through the change of the adsorption tower outlet pressure, and the channel pipeline replacement and sampling and injection actions can be completed.

[0028] step: The main channel can be used to test the samples after the product gas buffer tank of the pressure swing adsorption device. At this time, all the cut-off valves of the multi-channel A are closed. The gas passes through the outlet cut-off valve 2 of the product gas buffer tank and the multi-channel injection cut-off valve 4. Before injection, the gas is reduced to below 0.2Mpa through the pressure reducing valve 5, and enters the analysis and inspection system through the multi-channel injection valve 6. After passing through the analysis injection valve 7 and the analysis injection pressure transmitter 8, it is reduced to 0.1Mpa through the standard gas / sample three-way valve 9, the filter 11, and the pressure reducing valve 5, and enters the analyzer 12 injection system, and is emptied to the torch through the check valve 13 and the analyzer flare valve 14.

[0029] When the online diagnostic system is started, all shut-off valves are closed in the initial state, and all valves are open. Take channel A as an example. When the purified gas enters adsorption tower A, the outlet pressure transmitter 1 will rise from low pressure to the purification system pressure of 2.8Mpa. At this time, the outlet shut-off valve 2 of channel A is opened, and the product gas produced by adsorption tower A is used to replace sampling channel A. When the pressure of multi-channel pressure transmitter 3 rises to 2Mpa, the outlet shut-off valve 2 of adsorption tower A is closed, and the drain shut-off valve 16 of channel A is opened. After the gas in the pipeline of channel A is emptied, the drain shut-off valve 16 of channel A is closed, and the pipeline replacement of channel A is completed twice. It is experimentally measured that when the outlet pressure of the adsorption tower drops to 2.5MPa, the purification stage is ended. Based on this, the automatic recognition threshold is set to 2.5Mpa. When the pressure of pressure transmitter 1 of adsorption tower A drops to 2.5 Mpa, open the outlet shut-off valve 2 of adsorption tower A, and when the pressure of channel A pressure transmitter 3 rises to 2Mpa, close the outlet shut-off valve 2 of adsorption tower A, and open the multi-channel injection shut-off valve 4 at the same time, and close it after 2 seconds. Check that the pressure of the analytical injection pressure transmitter 8 drops to 0Mpa, and then open the multi-channel injection shut-off valve 4 again. After repeating 3 times, open the multi-channel injection shut-off valve 4 for injection. At this time, the diagnostic system prepares the injection instruction for the analyzer 12. After the analyzer 12 is stable, start to detect and diagnose the purification capacity of the adsorption tower A.

[0030] like Figure 2 As shown, the control module system detects the system pressure through the pressure transmitter and controls the opening and closing of the cut-off valve through the output signal.

[0031] This system can set the opening / closing time of the replacement analysis channel according to the cycle time of the purified gas.

[0032] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept, which all belong to the protection scope of the present invention.

Claims

1. A pressure swing adsorption tower online diagnosis and control system, characterized in that: include: Product gas buffer tank, used to store product gas from the pressure swing adsorption device; A main passage, connected to the product gas buffer tank and the analyzer (12), for conveying product gas during normal testing; A multi-channel pipeline includes a plurality of branch channels, each of which is connected to an adsorption tower and is used to individually detect the product gas of each adsorption tower; Automatic control unit, used to control the valve switches of the main channel and multi-channel pipelines to achieve automatic switching of detection modes; An analyzer (12) is used to analyze the composition of the product gas to evaluate the purification effect of the adsorption tower; It also includes an outlet pressure transmitter (1), a multi-channel pressure transmitter (3), a pressure reducing valve (5), an injection system and an exhaust system. The automatic control unit automatically identifies the purification or analysis process of the adsorption tower according to the change of the outlet pressure of the adsorption tower, and completes the channel pipeline replacement and sampling and injection actions.

2. The pressure swing adsorption tower online diagnosis and control system according to claim 1, characterized in that: The multi-channel pipeline comprises: A multi-channel sample injection cut-off valve (4) for controlling the passage of product gas into the analyzer (12); An analytical injection valve (7) for introducing product gas into an analyzer (12); The analytical sample injection pressure transmitter (8) is used to detect the sample injection pressure.

3. The pressure swing adsorption tower online diagnosis and control system according to claim 1, characterized in that: The emptying system comprises: A drain cut-off valve (16) for controlling the discharge of gas in the pipeline; Flare valve (18) is used to discharge gas to the flare system.

4. The pressure swing adsorption tower online diagnosis and control system according to claim 1, characterized in that: The automatic control unit comprises: A control logic module is used to automatically control the opening and closing of the valve according to pressure changes; The data processing module is used to process the detection data of the analyzer (12) and evaluate the purification effect of the adsorption tower.

5. The pressure swing adsorption tower online diagnosis and control system according to claim 1, characterized in that: The analyzer (12) is connected to: A standard gas / sample three-way valve (9) is used to switch the passages of the standard gas and the sample gas; The filter (11) is used to filter impurities in the product gas.

6. The pressure swing adsorption tower online diagnosis and control system according to claim 1, characterized in that: A safety valve (15) is also included to prevent the system from over-pressure.

7. A control method for an online diagnostic control system for a pressure swing adsorption tower according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. In normal detection mode, the automatic control unit opens the outlet shut-off valve (2) of the main channel, closes all the shut-off valves of the multi-channel pipeline, and the product gas enters the analyzer (12) through the main channel for detection; S2. In the diagnostic mode, the automatic control unit closes the outlet shut-off valve (2) of the main passage, opens the shut-off valve of a branch passage of the multi-pass pipeline in sequence, and uses the product gas of the adsorption tower to replace the gas in the branch passage; S3. When the pressure in the branch passage reaches the set value, the automatic control unit closes the shut-off valve of the branch passage and opens the exhaust shut-off valve (16) to exhaust the gas in the pipeline; S4. Repeat steps S2 and S3 to detect the product gas of each adsorption tower separately.

8. The control method according to claim 7, characterized in that: In step S1, the product gas passes through the outlet pressure transmitter (1) and the multi-channel pressure transmitter (3) and enters the analyzer (12) for detection.

9. The control method according to claim 7, characterized in that: In step S2, the automatic control unit automatically identifies the adsorption tower purification or analysis process according to the change of the adsorption tower outlet pressure.

10. The control method according to claim 7, characterized in that: In step S3, the branch passage after being emptied reduces its pressure through the pressure reducing valve (5) to a pressure range suitable for detection by the analyzer (12), and then enters the analyzer (12) for detection.

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