Integrated control system and control method for compressed air and nitrogen

Abstract

The present application relates to nitrogen, compressed air switching, especially to a compressed air and nitrogen integrated control system and control method. It can realize remote switching and confirmation between nitrogen and compressed air, and completely avoid the possibility of mutual collusion of the two gases, significantly improve the safety and efficiency of steel production. Including: nitrogen branch, the branch is used for connection between nitrogen source and user. Nitrogen bypass pipeline, the pipeline is connected with the nitrogen branch in parallel, and the nitrogen bypass manual valve is installed on the nitrogen bypass pipeline. Nitrogen emergency shutdown pipeline, the pipeline is connected with the nitrogen branch in parallel, and the nitrogen emergency electric valve and the nitrogen emergency check valve are installed in series on the nitrogen emergency shutdown pipeline. Compressed air branch, the branch is used for connection between compressed air source and user. Compressed air bypass pipeline, the pipeline is connected with the compressed air branch in parallel, and the compressed air bypass manual valve is installed on the compressed air branch.

Description

Technical Field

[0001] This invention relates to nitrogen and compressed air switching, and more particularly to an integrated control system and method for compressed air and nitrogen. Background Technology

[0002] In steel plants, switching between nitrogen and compressed air is a common process operation. To meet production requirements, the energy medium supply must be rapid, stable, and safe. Depending on the process conditions, nitrogen is sometimes needed, while compressed air is required at other times. Traditionally, this process typically requires operators to manually adjust field valves or remotely control electric valves from a central control room, followed by on-site verification of valve status. This approach not only suffers from delays, impacting efficiency, but also hinders the continuity and stability of the production process.

[0003] Furthermore, traditional switching methods cannot effectively isolate different media, posing a risk of gas cross-contamination, which may interfere with or even damage related steel manufacturing processes. Currently, the two main methods—manual on-site operation and remote control followed by on-site verification—cannot guarantee that nitrogen and compressed air will not mix, thus increasing operational uncertainty and risk. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing an integrated control system and method for compressed air and nitrogen. It offers a solution that enables remote switching and confirmation between nitrogen and compressed air, completely eliminating the possibility of cross-contamination between the two gases, significantly improving the safety and efficiency of steel production. This solution has been specifically adapted to the specific needs of steel plants to better serve the industry's unique environment and technical requirements.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an integrated compressed air and nitrogen control system, comprising:

[0006] Nitrogen branch (P1) is used for the connection between the nitrogen system and the user. Nitrogen manual valve a, nitrogen check valve, nitrogen electric valve a, nitrogen pressure relief valve, nitrogen electric valve b and nitrogen manual valve b are installed in sequence on this branch.

[0007] A nitrogen bypass line (P2) is connected in parallel with the nitrogen branch line (P1). A nitrogen bypass manual valve is installed on the nitrogen bypass line (P2) to provide a direct path for the gas.

[0008] Nitrogen emergency pipeline (P3) is connected in parallel with nitrogen branch (P1). Nitrogen emergency electric valve and nitrogen emergency check valve are installed in series on nitrogen emergency pipeline (P3), and the nitrogen emergency electric valve is controlled by a remote control system.

[0009] Compressed air branch (P4), which is used for the connection between the compressed air system and the user, is equipped with compressed air manual valve a, compressed air check valve, compressed air electric valve a, compressed air pressure relief valve, compressed air electric valve b, and compressed air manual valve b in sequence.

[0010] Compressed air bypass line (P5), which is connected in parallel with compressed air branch line (P4), and compressed air bypass manual valve installed on compressed air bypass line (P5) to provide a direct path for delivering compressed air.

[0011] Furthermore, the integrated compressed air and nitrogen control system also includes:

[0012] The nitrogen branch pressure measuring point is set on the nitrogen branch (P1) to monitor the pressure of the nitrogen branch (P1).

[0013] The pressure measuring point of the compressed air branch is set on the compressed air branch (P4) to monitor the pressure of the compressed air branch.

[0014] The user-end pipeline (P6) is used to connect to the nitrogen branch (P1) or the compressed air branch (P4) to deliver gas to the user end.

[0015] The user pressure measurement point is installed on the user-end pipeline (P6) to monitor the pressure at the user end.

[0016] The user flow measurement point is set on the user-end pipeline (P6) to monitor the gas flow rate to the user.

[0017] The nitrogen system pressure measuring point is installed in the nitrogen system to monitor the pressure status of the entire nitrogen system.

[0018] Pressure measuring points in compressed air systems are installed within the compressed air system to monitor the pressure status of the entire compressed air system.

[0019] Remote control systems are used to integrate all data and manage the automated operation of the entire system.

[0020] On-site indicator lights are used to display the current status for reference by on-site staff.

[0021] Furthermore, a first parallel branch is provided outside the nitrogen electric valve a, and the first parallel branch is provided with a nitrogen pressurization valve; a second parallel branch is provided outside the compressed air electric valve a, and the second parallel branch is provided with a compressed air pressurization valve.

[0022] The integrated control method for compressed air and nitrogen includes: the control method is based on a control system, and the control method includes three operating conditions:

[0023] Operating Condition 1: Compressed air is switched to nitrogen.

[0024] Operating condition 2: Nitrogen is switched to compressed air.

[0025] Operating condition 3: Switch to emergency gas source.

[0026] Furthermore, in operating condition one, the steps include:

[0027] S11. Compressed air is used as the primary air source in dust removal or desulfurization processes.

[0028] S12. When the remote control system detects that the real-time pressure P of the compressed air system is decreasing at a rate v, calculate the time t = (P - Px) / v for the pressure to drop to the minimum safe pressure limit Px.

[0029] S13. Considering the device switching action time t1, determine the actual monitored safety pressure Ps=t1*v+Px.

[0030] S14. Based on the operating times of nitrogen electric valve a, nitrogen electric valve b, nitrogen pressure relief valve, and nitrogen charging valve, and the pipe section volume V between nitrogen electric valve a and nitrogen electric valve b, calculate the equalization time tc = V / Vn, where Vn is the charging flow rate identified based on the nitrogen system pressure Pn.

[0031] S15. Calculate the switching time t1 = tnb + tna + tnx + tc, and update the monitoring safety pressure Ps accordingly; where tnb represents the action time of nitrogen electric valve b, tna represents the action time of nitrogen electric valve a, and tnx represents the action time of nitrogen pressure relief valve.

[0032] S16. The control system monitors the nitrogen system pressure Pn and compressed air pressure drop rate v in real time with a 1-second scan cycle.

[0033] S17. When the real-time pressure P of the compressed air system is less than the monitored safety pressure Ps plus the redundant pressure Pr, output the control result and switch the compressed air to nitrogen.

[0034] S18. The remote control system sends a signal to the gas consumption point to indicate that the current gas source has been switched to nitrogen.

[0035] Furthermore, when the device is put into operation, nitrogen manual valve a, nitrogen manual valve b, compressed air manual valve a, and compressed air manual valve b are in the open state and are only used for maintenance of the nitrogen branch and compressed air branch; while nitrogen bypass manual valve, compressed air bypass manual valve, and nitrogen emergency electric valve are closed when the device is put into operation and are only used for emergency purposes.

[0036] The compressed air system pressure fluctuation range is 0.55Mpa-0.78Mpa, and the user-end pressure fluctuation range is 0.45Mpa-0.68Mpa.

[0037] When a downward trend in the compressed air system pressure is detected and the pressure drop exceeds 0.01 MPa within 5 seconds, this rate of decrease is defined as 0.01 MPa / 5 seconds.

[0038] The minimum safe pressure limit Px is a constant designed according to the needs of each process. For the desulfurization process, this limit shall not be lower than 0.5 MPa.

[0039] Furthermore, in operating condition two, the steps include:

[0040] S21. The remote control system compares the real-time pressure P of the compressed air system with the monitored safety pressure Ps plus the redundant pressure Pr.

[0041] S22. When the remote control system recognizes that P>Ps+Pr and detects that the pressure trend of the compressed air system is rising, it outputs a control command to close the compressed air pressure relief valve, and continues to the next operation after confirming that the valve is in place.

[0042] S23. Open the compressed air pressurization valve to pressurize the pipe section located between compressed air electric valve a and compressed air electric valve b.

[0043] S24. Monitor and identify whether the value of the pressure measuring point of the compressed air branch located between the compressed air electric valve a and the compressed air electric valve is consistent with the value of the pressure measuring point of the compressed air system through the remote control system.

[0044] S25. When the pressure values ​​of the two measuring points match, close the compressed air pressurization valve, and then open the compressed air electric valve a and the compressed air electric valve b.

[0045] S26. Further monitor whether the pressure values ​​of the user's pressure measuring points are consistent with the values ​​of the compressed air system pressure measuring points through the remote control system.

[0046] S27. When the pressure value at the user's pressure measuring point matches the value at the compressed air system pressure measuring point, the remote control system will indicate that the compressed air branch has been opened.

[0047] S28. Close nitrogen electric valve a and nitrogen electric valve b. After confirming that both electric valves are in position, open the nitrogen pressure relief valve to relieve pressure in the nitrogen branch.

[0048] S29. Monitor the value of the nitrogen branch pressure measuring point located between nitrogen electric valve a and nitrogen electric valve b through the remote control system until the value is identified as zero, at which point it indicates that the nitrogen branch has been closed.

[0049] S210, the remote control system sends a signal to the field indicator light, indicating that nitrogen has been successfully switched to compressed air.

[0050] Furthermore, before closing the compressed air pressure relief valve, the remote control system first confirms that the pressure trend of the compressed air system is rising.

[0051] Before opening the compressed air pressurization valve, first confirm that the compressed air relief valve is completely closed.

[0052] Before opening the compressed air electric valve a and compressed air electric valve b, it is necessary to ensure that the pressure values ​​of the compressed air branch pressure measuring point are consistent with the pressure measuring point of the compressed air system.

[0053] Before closing, nitrogen electric valves a and b must wait for the pressure values ​​at the user's pressure measuring point to match the pressure values ​​at the compressed air system's pressure measuring point.

[0054] Before opening the nitrogen pressure relief valve, it must be confirmed that both nitrogen electric valve a and nitrogen electric valve b are completely closed.

[0055] Before sending a signal that nitrogen has been successfully switched to compressed air, the remote control system needs to confirm that the pressure value at the nitrogen branch pressure measuring point is zero.

[0056] The redundant pressure Pr is a manually set safety margin used to ensure the safety of energy consumption in the process.

[0057] Furthermore, in operating condition three, the steps include:

[0058] S31. The remote control system monitors the value of the user's pressure measuring point and identifies that the value is less than the user's minimum safe pressure limit Px, where Px is a constant of the process's own properties.

[0059] S32. The remote control system simultaneously monitors the values ​​of user traffic measurement points and identifies that the values ​​are decreasing.

[0060] S33. When the above conditions are met, the remote control system outputs control commands to keep all electric valves in the nitrogen branch and compressed air branch in their current positions.

[0061] S34. Simultaneously open the nitrogen emergency electric valve and issue a fault warning through the remote control system.

[0062] S35. If the remote control system continues to detect that the value of the user's pressure measurement point is less than the user's minimum safe pressure limit Px and the value of the user's flow measurement point is still decreasing, then upgrade the fault warning.

[0063] S36. After the fault warning is upgraded, the remote control system identifies the values ​​of the pressure measuring points of the nitrogen system and the compressed air system.

[0064] S37. Based on the values ​​of the pressure measuring points of the nitrogen system and the compressed air system, select the branch with a value greater than Px and provide operation prompts for opening the nitrogen bypass manual valve or the compressed air bypass manual valve. The priority is: if the values ​​of the pressure measuring points of the nitrogen system and the compressed air system are both greater than Px, then the nitrogen bypass manual valve should be opened first.

[0065] Furthermore, when the value at the user's pressure measurement point is less than the user's minimum safe pressure limit Px, the remote control system immediately takes measures to prevent further pressure drop.

[0066] After the fault warning is upgraded, the remote control system will provide clear operation instructions to guide the operator to open the corresponding bypass manual valve to restore the gas supply.

[0067] If either the pressure measurement point of the nitrogen system or the pressure measurement point of the compressed air system has a value greater than Px, the remote control system will instruct the bypass manual valve of the corresponding branch with the higher pressure to be opened.

[0068] The minimum safe pressure limit Px for users is a constant designed according to the specific needs of each process, used to ensure the safe operation of the process.

[0069] Compared with the prior art, the present invention has the following advantages.

[0070] This invention enables controlled switching between nitrogen and compressed air. The system can automatically issue commands to coordinate the operation of multiple valve groups, thereby achieving integrated switching between the two gas sources. Furthermore, the system has remote feedback and early warning functions to ensure that the risk of cross-contamination between nitrogen and compressed air is eliminated during the switching process.

[0071] 1. This invention enables automatic switching between two gas sources: nitrogen and compressed air.

[0072] 2. Pressure measuring points and pressure relief valves are installed in the pipe sections between the electric valves, which can perform status self-checks after switching and feed the results back to the control system.

[0073] 3. The presence of the pressure relief valve prevents cross-contamination between the two media—nitrogen and compressed air.

[0074] 4. The system makes predictions based on the pressure trend of the compressed air system, thereby completing the timely switching of the device. Attached Figure Description

[0075] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following description.

[0076] Figure 1 This is a block diagram of an integrated compressed air and nitrogen control system.

[0077] Figure 2 This is a schematic diagram of the comparison table of the embodiments.

[0078] In the diagram, 1. Nitrogen manual valve a, 2. Nitrogen check valve, 3. Nitrogen pressurization valve, 4. Nitrogen electric valve a, 5. Nitrogen pressure relief valve, 6. Nitrogen electric valve b, 7. Nitrogen manual valve b, 8. Nitrogen bypass manual valve.

[0079] 9. Compressed air manual valve a; 10. Compressed air check valve; 11. Compressed air pressurization valve; 12. Compressed air electric valve a; 13. Compressed air pressure relief valve; 14. Compressed air electric valve b; 15. Compressed air manual valve b; 16. Compressed air bypass manual valve; 17. Nitrogen emergency electric valve; 18. Nitrogen emergency check valve.

[0080] 19. Nitrogen branch pressure measurement point; 20. Compressed air branch pressure measurement point; 21. Compressed air system pressure measurement point; 22. Nitrogen system pressure measurement point; 23. User pressure measurement point; 24. User flow measurement point; 25. Remote control system; 26. On-site indication. Detailed Implementation

[0081] To make the objectives, technical solutions, and beneficial effects of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0082] like Figure 1-2 As shown, the integrated compressed air and nitrogen control system allows either nitrogen or compressed air (usually compressed air) to serve as the user's primary gas source, while the other gas source serves as a backup, depending on the process requirements.

[0083] Working principle explanation: Taking compressed air as the primary air source, during the use of compressed air, the remote control system monitors the compressed air system pressure in real time and calculates the rate of pressurization or depressurization.

[0084] When the pressure drop rate and real-time pressure meet the switching conditions, the nitrogen switching valve group begins to open: the pressure relief valve is closed, and after the valve is detected to be in position, the pressure charging valve is opened. After the pressure measuring point of the nitrogen branch is detected to match the pressure measuring point of the nitrogen system, the two electric valves of the nitrogen branch are opened, and the pressure charging valve is closed simultaneously. The opening of the nitrogen branch is complete.

[0085] At the same time, the pressure at the user pressure measuring point matches the pressure at the nitrogen branch pressure measuring point and the nitrogen system pressure, indicating that the nitrogen branch has ended its operation.

[0086] The compressed air valve assembly begins to close, simultaneously closing the two electric valves in the compressed air branch. After detecting that the two electric valves are fully closed, the pressure relief valve is opened, and the pressure measuring point of the compressed air branch is monitored to be zero, indicating that the closure of the compressed air branch is complete.

[0087] Meanwhile, the remote monitoring system indicates that the gas source has been switched to nitrogen. This achieves remote switching, remote confirmation, and prevention of cross-contamination between nitrogen and compressed air. Each branch includes manual valves at both ends. When the branch is in normal operation, both valves are open. If any component in the branch malfunctions, both manual valves can be closed for maintenance without affecting the normal function of other branches or the user's energy consumption. Each branch's main pipeline has a check valve to further ensure the isolation effect of the manual valves on the process side when the branch is not in use. Two electric valves are installed on each branch's main pipeline for remote control of the branch's operation and shutdown. A pressure relief valve branch is added to the main pipeline between the two electric valves in each branch to release residual gas between the two electric valves when the branch is not in operation.

[0088] Simultaneously, a pressure measuring point is added to the main pipeline between the two electric valves to detect the pressure between them and serve as a criterion for determining the effective isolation of this branch. Utilizing the stability of the nitrogen system, a nitrogen source is provided as an emergency gas source. If a system switching failure is detected and the user's pressure falls below the safety limit, the emergency gas source will immediately open, and the remote control system will issue an alarm. The original switching valve is retained for manual opening in case of sudden system power failures or other abnormal situations to ensure power supply to the user.

[0089] Specifically, the integrated compressed air and nitrogen control system includes a nitrogen branch consisting of a nitrogen manual valve a1, a nitrogen check valve 2, a nitrogen pressurization valve 3, a nitrogen electric valve a4, a nitrogen pressure relief valve 5, a nitrogen electric valve b6, a nitrogen manual valve b7, a nitrogen bypass manual valve 8, and a nitrogen branch pressure measuring point 19.

[0090] The compressed air branch consists of a compressed air manual valve a9, a compressed air check valve 10, a compressed air pressurizing valve 11, a compressed air electric valve a12, a compressed air pressure relief valve 13, a compressed air electric valve b14, a compressed air manual valve b15, a compressed air bypass manual valve 16, and a compressed air branch pressure measuring point 20.

[0091] The emergency branch consists of a nitrogen emergency electric valve 17 and a nitrogen emergency check valve 18.

[0092] It consists of an auxiliary unit including compressed air system pressure measuring point 21, nitrogen system pressure measuring point 22, user pressure measuring point 23, user flow measuring point 24, remote control system 25, and field indication 26.

[0093] Example 1: Switching compressed air to nitrogen:

[0094] In dust removal or desulfurization processes, compressed air is used as the primary air source. Due to significant pressure fluctuations in the compressed air system, the source pressure typically fluctuates between 0.55 MPa and 0.78 MPa, while the user pressure fluctuates between 0.45 and 0.68 MPa (most users experience pressure fluctuations due to shocks). The remote control system 25 monitors the real-time pressure fluctuations (P) and pressure drop rate (v) of the compressed air system (if the system pressure shows a downward trend, and the pressure drops by more than 0.01 MPa per unit time, e.g., 5 seconds, the pressure drop rate is 0.01 MPa / 5s). This is combined with the user's minimum safe pressure limit (Px), which is a constant and a characteristic of the process itself. (For example, in the desulfurization process, the power gas pressure must not be lower than 0.5 MPa; this value is the minimum pressure designed by each process according to its own needs, i.e., the safe pressure). Therefore, the estimated time for the pressure to drop to the safe pressure is t = (P - Px) / v. Since there is an action time t1 (a constant characteristic of the device itself) for device switching, the actual monitored safe pressure Ps = t1 * v + Px can be calculated.

[0095] The switching action time t1 of the devices is as follows: tnb for nitrogen electric valve b6, tna for nitrogen electric valve a4, tnx for nitrogen pressure relief valve 5, and tnj for nitrogen equalizing valve 3. Where tnb, tna, tnj, and tnx are inherent properties of the valves and are constants.

[0096] Equalization time tc: The pipe diameter d is used for pressing, and the real-time nitrogen monitoring pressure Pn is used. A flow rate comparison table can be established based on the pipe diameter and pressure. The flow rate comparison table is embedded in the remote control system 25. The pressurization flow rate Vn is identified based on the pressure of the nitrogen system 22. The pipe section volume V between nitrogen electric valve a 4 and nitrogen electric valve b 6 (the device's own attribute, a constant) is used. Then, the equalization time tc = V / Vn, and the switching time t1 = tnb + tna + tnx + tc.

[0097] Monitoring the safe pressure of compressed air: Ps = (tnb + tna + tnx + V / Vn) * v + Px. Because the nitrogen pressure Pn and the compressed air pressure drop rate v change in real time, the control system needs to identify (scanning cycle 1s) the nitrogen system 22 pressure and the compressed air pressure drop rate in real time and output the results. Based on the comparison between the real-time pressure of the compressed air system 21 and the monitored safe pressure, if P < Ps + Pr (redundant pressure, ensuring energy safety in the process, manually set, can be combined with emergency time), the control result is output: compressed air is switched to nitrogen. Simultaneously, the remote control system user 25 sends a signal to the on-site indicator 26 at the gas consumption point, indicating that the current gas source is nitrogen.

[0098] When put into operation, nitrogen manual valve a1, nitrogen manual valve b7, compressed air manual valve a9, and compressed air manual valve b15 are in the open state and are only used for maintenance of the nitrogen branch and compressed air branch, and are not involved in switching or adjustment; nitrogen bypass manual valve 8, compressed air bypass manual valve 16, and nitrogen emergency electric valve 17 are in the closed state when the device is put into operation and are only used for emergency purposes.

[0099] The specific switching action is as follows:

[0100] The remote control system 25 compares the real-time pressure of the compressed air system 21 with the monitored safety pressure and identifies that P < P<P<0.05. s +P r .

[0101] The remote control system outputs control valve actions:

[0102] After closing the nitrogen pressure relief valve 5 and verifying that the valve is in position, open the nitrogen charging valve 3 to charge the pipe section between nitrogen electric valves a 4 and b 6. Once the remote control system 25 identifies that the pressure value at nitrogen branch pressure measuring point 19 matches the pressure value at nitrogen system pressure measuring point 22, close the nitrogen charging valve 3 and open nitrogen electric valves a 4 and b 6. After the remote control system 25 identifies that the pressure value at user pressure measuring point 24 matches the pressure value at nitrogen system pressure measuring point 22 (theoretically, the values ​​should be equal, but considering the distance and order of the two measuring points, pressure drop caused by pipeline obstruction and instrument measurement errors need to be fully considered, and a range should be given), for example, P... 22 =P 24 (±0.005 MPa, which matches the default value), indicating that the nitrogen branch is open. Close compressed air electric valves a 12 and b 14. After both valves are in position, open compressed air pressure relief valve 13 to release pressure. Once the remote control system 25 detects that the pressure measurement point of compressed air branch 20 is zero, it indicates that compressed air branch 20 is closed. Simultaneously, the remote control system 25 sends a signal to the field indicator 26: compressed air has been switched to nitrogen.

[0103] Example 2: Nitrogen gas was switched to compressed air.

[0104] The remote control system 25 identifies that P > P by comparing the real-time pressure of the compressed air system 21 with the monitored safety pressure. s +P r The remote control system 25 detects that the pressure trend at the pressure measuring point 21 of the compressed air system is rising, and outputs control valve actions: after closing the compressed air pressure relief valve 13 and detecting that the valve is in position, it opens the compressed air charging valve 11 to charge the pipe section between the compressed air electric valves a 12 and b 14. After the remote control system 25 detects that the value of the compressed air branch pressure measuring point 20 matches the value of the compressed air system pressure measuring point 21, it closes the compressed air charging valve 11 and opens the compressed air electric valves a 12 and b 14. After the remote control system 25 detects that the pressure value at the user pressure measuring point 24 matches the value of the compressed air system pressure measuring point 21, it prompts that the compressed air branch has been opened; it closes the nitrogen electric valves a 4 and b 6. After the two electric valves are in position, it opens the nitrogen pressure relief valve 5 to release pressure. After the remote control system 25 detects that the value of the nitrogen branch pressure measuring point 19 is zero, it prompts that the compressed air branch has been closed. At the same time, the remote control system 25 sends a signal to the field indicator 26: nitrogen has been switched to nitrogen.

[0105] Example 3: Switch to emergency gas source.

[0106] The remote control system 25 detects that the value at user pressure measuring point 24 is less than the user's minimum safe pressure limit Px (a process-specific attribute, a constant), and that the value at user flow measuring point 23 is decreasing. The remote control system 25 then outputs a control valve action:

[0107] All electric valves in the nitrogen branch and compressed air branch are in the holding position, while the nitrogen emergency electric valve 17 is opened, and the remote control system 25 issues a fault warning.

[0108] If the remote control system 25 still detects that the user's pressure measurement point 24 value is less than the user's minimum safe pressure limit Px, and the user's flow measurement point 23 value shows a downward trend, then the remote control system 25 will escalate the warning and identify the values ​​of the nitrogen system pressure measurement point 22 and the compressed air system pressure measurement point 21. It will then select the branch with the value greater than Px and provide an operation prompt to open either the nitrogen bypass manual valve 8 or the compressed air bypass manual valve 16. Priority: If both the nitrogen system pressure measurement point 22 and the compressed air system pressure measurement point 21 values ​​are greater than Px, the nitrogen bypass manual valve 8 will be selected.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Therefore, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. An integrated control system for compressed air and nitrogen, characterized in that, include: Nitrogen branch (P1), which is used for the connection between the nitrogen system and the user, is equipped with nitrogen manual valve a (1), nitrogen check valve (2), nitrogen electric valve a (4), nitrogen pressure relief valve (5), nitrogen electric valve b (6) and nitrogen manual valve b (7) in sequence. A nitrogen bypass line (P2) is connected in parallel with a nitrogen branch line (P1). A nitrogen bypass manual valve (8) is installed on the nitrogen bypass line (P2) to provide a direct path for gas delivery. Nitrogen emergency pipeline (P3), which is connected in parallel with nitrogen branch (P1), nitrogen emergency electric valve (17) and nitrogen emergency check valve (18) are installed in series on nitrogen emergency pipeline (P3), and nitrogen emergency electric valve (17) is controlled by remote control system; Compressed air branch (P4), which is used for the connection between the compressed air system and the user, is equipped with compressed air manual valve a (9), compressed air check valve (10), compressed air electric valve a (12), compressed air pressure relief valve (13), compressed air electric valve b (14), and compressed air manual valve b (15) in sequence. A compressed air bypass line (P5) is connected in parallel with a compressed air branch line (P4). A compressed air bypass manual valve (16) is installed on the compressed air bypass line (P5) to provide a direct path for delivering compressed air. A first parallel branch is provided outside the nitrogen electric valve a (4), and a nitrogen pressurization valve (3) is provided in the first parallel branch; a second parallel branch is provided outside the compressed air electric valve a (12), and a compressed air pressurization valve (11) is provided in the second parallel branch. The process of switching from compressed air to nitrogen includes the following steps: S11. Compressed air is used as the primary air source in dust removal or desulfurization processes. S12. When the remote control system (25) detects that the real-time pressure P of the compressed air system (21) is decreasing at a rate v, calculate the time t = (P-Px) / v when the pressure is expected to drop to the minimum safe pressure limit Px. S13. Considering the switching action time t1, determine the actual monitored safety pressure Ps=t1*v+Px; S14. Based on the action time of nitrogen electric valve a (4), nitrogen electric valve b (6), nitrogen pressure relief valve and nitrogen charging valve, and the pipe section volume V between nitrogen electric valve a (4) and nitrogen electric valve b (6), calculate the equalization time tc=V / Vn, where Vn is the charging flow rate identified based on the nitrogen system pressure Pn. S15. Calculate the switching time t1=tnb+tna+tnx+tc, and update the monitoring safety pressure Ps accordingly; where tnb represents the action time of nitrogen electric valve b (6), tna represents the action time of nitrogen electric valve a (4), and tnx represents the action time of nitrogen pressure relief valve (5). S16. The control system monitors the nitrogen system pressure Pn and compressed air pressure drop rate v in real time with a 1-second scan cycle. S17. When the real-time pressure P of the compressed air system is less than the monitored safety pressure Ps plus the redundant pressure Pr, output the control result and switch the compressed air to nitrogen. S18. The remote control system sends a signal to the gas consumption point to indicate that the current gas source has been switched to nitrogen.

2. The integrated compressed air and nitrogen control system according to claim 1, characterized in that: Also includes: The nitrogen branch pressure measuring point (19) is set on the nitrogen branch (P1) to monitor the pressure of the nitrogen branch (P1); The compressed air branch pressure measuring point (20) is set on the compressed air branch (P4) to monitor the pressure of the compressed air branch; The user-end pipeline (P6) is used to connect to the nitrogen branch (P1) or the compressed air branch (P4) to deliver the gas to the user end. The user pressure measurement point (23) is set on the user end pipeline (P6) to monitor the pressure at the user end; The user flow measurement point (24) is set on the user end pipeline (P6) to monitor the gas flow to the user; Nitrogen system pressure measuring point (22) is set in the nitrogen system to monitor the pressure status of the entire nitrogen system; The compressed air system pressure measuring point (21) is set in the compressed air system to monitor the pressure status of the entire compressed air system; A remote control system (25) is used to integrate all data and manage the automated operation of the entire system; The on-site indicator light (26) is used to display the current status for on-site staff to refer to.

3. An integrated control method for compressed air and nitrogen, characterized in that, include: The control method is based on a control system, and the control system is the control system described in any one of claims 1-2; the control method includes three operating conditions: Operating condition 1: Compressed air is switched to nitrogen; Operating condition 2: Switch from nitrogen to compressed air; Operating condition 3: Switch to emergency gas source.

4. The method according to claim 3, characterized in that: When put into operation, nitrogen manual valve a, nitrogen manual valve b, compressed air manual valve a, and compressed air manual valve b are in the open position and are only used for maintenance of the nitrogen branch and compressed air branch; while nitrogen bypass manual valve, compressed air bypass manual valve, and nitrogen emergency electric valve are closed when put into operation and are only used for emergency purposes. The compressed air system pressure fluctuation range is 0.55 MPa-0.78 MPa, and the user-end pressure fluctuation range is 0.45 MPa-0.68 MPa. When a downward trend in the compressed air system pressure is detected and the pressure drop exceeds 0.01 MPa within 5 seconds, this rate of decrease is defined as 0.01 MPa / 5 seconds. The minimum safe pressure limit Px is a constant designed according to the needs of each process. For the desulfurization process, this limit shall not be lower than 0.5 MPa.

5. The method according to claim 3, characterized in that: Condition 2 includes the following steps: S21, The remote control system (25) compares the real-time pressure P of the compressed air system (21) with the monitored safety pressure Ps plus the redundant pressure Pr. S22. When the remote control system (25) recognizes that P>Ps+Pr and detects that the pressure trend of the compressed air system (21) is rising, it outputs a control command to close the compressed air pressure relief valve (13) and continues the next operation after confirming that the valve is in place. S23. Open the compressed air pressurization valve (11) to pressurize the pipe section located between the compressed air electric valve a (12) and the compressed air electric valve b (14); S24. Monitor and identify, through remote control system (25), whether the value of the compressed air branch pressure measuring point (20) located between compressed air electric valve a (12) and compressed air electric valve b (14) is consistent with the value of the compressed air system pressure measuring point (21); S25. When the pressure values ​​of the two measuring points match, close the compressed air pressurization valve (11), and then open the compressed air electric valve a (12) and the compressed air electric valve b (14). S26. Further monitor whether the pressure value of the user pressure measuring point (24) is consistent with the value of the compressed air system pressure measuring point (21) through the remote control system (25); S27. When the pressure value of the user pressure measuring point (24) matches the value of the compressed air system pressure measuring point (21), the remote control system (25) prompts that the compressed air branch has been opened. S28. Close nitrogen electric valve a (4) and nitrogen electric valve b (6). After confirming that both electric valves are in place, open nitrogen pressure relief valve (5) to relieve pressure in the nitrogen branch. S29. Monitor the value of the nitrogen branch pressure measuring point (19) located between nitrogen electric valve a (4) and nitrogen electric valve b (6) through the remote control system (25) until the value is identified as zero. At this time, it indicates that the nitrogen branch has been closed. S210, the remote control system (25) sends a signal to the field indicator (26) to indicate that nitrogen has been successfully switched to compressed air.

6. The method according to claim 5, characterized in that: Before closing the compressed air pressure relief valve (13), the remote control system (25) first confirms that the pressure trend of the compressed air system (21) is rising; Before opening the compressed air pressurization valve (11), first confirm that the compressed air pressure relief valve (13) is completely closed; Before the compressed air electric valve a (12) and compressed air electric valve b (14) are opened, it is necessary to ensure that the pressure values ​​of the compressed air branch pressure measuring point (20) and the compressed air system pressure measuring point (21) are consistent. Before the nitrogen electric valve a (4) and nitrogen electric valve b (6) are closed, they need to wait for the pressure value of the user pressure measuring point (24) to be consistent with the pressure value of the compressed air system pressure measuring point (21); Before opening the nitrogen pressure relief valve (5), it is necessary to confirm that both the nitrogen electric valve a (4) and the nitrogen electric valve b (6) are completely closed. Before sending a signal that nitrogen has been successfully switched to compressed air, the remote control system (25) needs to confirm that the pressure value of the nitrogen branch pressure measuring point (19) is zero. The redundant pressure Pr is a manually set safety margin used to ensure the safety of energy consumption in the process.

7. The method according to claim 3, characterized in that: Operating condition three includes the following steps: S31. The remote control system (25) monitors the value of the user pressure measuring point (24) and identifies that the value is less than the user's minimum safe pressure limit Px, where Px is a constant of the process's own properties. S32, The remote control system (25) simultaneously monitors the value of the user flow measurement point (23) and identifies that the value is decreasing; S33. When the above conditions are met, the remote control system (25) outputs control commands to keep all electric valves in the nitrogen branch and compressed air branch in their current positions. S34. Simultaneously open the nitrogen emergency electric valve (17) and issue a fault warning through the remote control system (25); S35. If the remote control system (25) continues to identify that the value of the user pressure measurement point (24) is less than the user's minimum safe pressure limit Px and the value of the user flow measurement point (23) is still decreasing, then upgrade the fault warning. S36. After the fault warning is upgraded, the remote control system (25) identifies the values ​​of the nitrogen system pressure measuring point (22) and the compressed air system pressure measuring point (21); S37. Based on the values ​​of the nitrogen system pressure measuring point (22) and the compressed air system pressure measuring point (21), select the branch that is greater than Px and give the operation prompt to open the nitrogen bypass manual valve (8) or the compressed air bypass manual valve (16). The priority is: if the values ​​of the nitrogen system pressure measuring point (22) and the compressed air system pressure measuring point (21) are both greater than Px, then the nitrogen bypass manual valve (8) should be opened first.

8. The method according to claim 7, characterized in that: When the value of the user pressure measuring point (24) is less than the user's minimum safe pressure limit Px, the remote control system (25) immediately takes measures to prevent further pressure drop; After the fault warning is upgraded, the remote control system (25) will provide clear operation instructions to guide the operator to open the corresponding bypass manual valve to restore the gas supply; If only one of the values ​​of the nitrogen system pressure measuring point (22) and the compressed air system pressure measuring point (21) is greater than Px, the remote control system (25) will instruct the bypass manual valve of the corresponding branch with higher pressure to be opened. The minimum safe pressure limit Px for users is a constant designed according to the specific needs of each process, used to ensure the safe operation of the process.

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