System and process for reducing mechanical cleaning of prone-to-plugging valves

Abstract

This invention discloses a system and process for reducing the frequency of mechanical cleaning of easily clogged valves. Line A connects to a reactor at its left and right ends, and includes valves HV1, LV1, a pressure relief valve, and HV2. A hot solvent flushing system is also connected to Line A. One end of Line B connects to the inlet of valve HV1, and the other end connects to the outlet of valve HV2. Line B includes valves HV5, a pressure relief valve, LV2, and HV6. A pipeline with valve HV4 is connected to Line A between valves HV1 and LV1. A pipeline with valve HV8 is connected to Line B between valves HV5 and LV2. Lines 1 and 2 converge and connect to a solvent recovery tank. A level control valve is installed inside the reactor. Both LV1 and LV2 control valves can be cascaded with the level control valve. This system features the ability to prevent valve clogging, reduce maintenance and repair work, and extend the long-term operation of the equipment.

Description

Technical Field

[0001] This invention relates to a system and its process, and more specifically, to a system and its process for reducing the number of times easily clogged valves need mechanical cleaning, belonging to the field of petrochemicals. Background Technology

[0002] Key breakthroughs in the development of the petroleum and chemical industry include: high-end polyolefins, high-carbon α-olefin comonomers (C6, C8), metallocene catalysts, and other key technologies. However, due to the special nature of high-carbon α-olefin reactions, polymers are inevitably generated in the reaction system. Therefore, how to reduce polymers in the system and efficiently clean polymers from easily clogged parts is a key area that needs to be addressed.

[0003] Currently, the main method involves installing a filter before the regulating valve. However, even with a filter, the reactants cannot be completely filtered due to their specific properties. Furthermore, the small diameter of the reactor outlet regulating valve causes throttling and pressure reduction as the material passes through, leading to frequent clogging. Cleaning the regulating valve after clogging is extremely time-consuming and labor-intensive. If the reaction is not ideal, the outlet regulating valve may not be able to be switched and cleaned in time, forcing the unit to shut down. The longer the shutdown time, the more the polymer cools, significantly increasing the difficulty of cleaning. Since the regulating valve cannot be cleaned in time during normal production, the backup line regulating valve is replaced with a ball valve for manual control. However, manual control is difficult, and personnel must remain near the manual valve, greatly increasing labor costs and the risk of misoperation. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a system and process method for reducing the number of times a valve prone to clogging needs to be mechanically cleaned. This system features the ability to prevent valve blockage, reduce maintenance and repair work, and extend the long-term operation of the equipment.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] The present invention provides a system for reducing the number of times mechanical cleaning of easily clogged valves, comprising A line and B line laid in a pipeline manner. The left and right ends of the A line are respectively connected to a reactor and a downstream system. The A line is sequentially connected to an HV1 valve, an LV1 control valve, a pressure relief valve equipped with a remote pressure gauge PZT1, and an HV2 valve. A hot solvent flushing system is connected between the pressure relief valve equipped with the remote pressure gauge PZT1 and the HV2 valve.

[0007] One end of line B is connected to the inlet of valve HV1, and the other end of line B is connected to the outlet of valve HV2. Line B is sequentially connected to valve HV5, pressure relief valve equipped with remote pressure gauge PZT2, control valve LV2, and valve HV6. Line A between valve HV1 and control valve LV1 is connected to pipeline No. 1 with valve HV4. Line B between valve HV5 and control valve LV2 is connected to pipeline No. 2 with valve HV8. Pipelines No. 1 and No. 2 converge and are connected to a solvent recovery tank.

[0008] The hot solvent flushing system includes a hot solvent recovery tank, which is connected to pipeline No. 3 equipped with a remote flow meter FI. The hot solvent flushing system is connected to line A via pipeline No. 3. An HV3 valve is also connected to pipeline No. 3. The inlet of the HV3 valve is connected to pipeline No. 4. Pipeline No. 4 is connected to line B between a pressure relief valve equipped with a remote pressure gauge PZT2 and valve No. 6. An HV7 valve is connected to pipeline No. 4. A liquid level control valve is provided in the reactor. Both LV1 and LV2 control valves can be cascaded with the liquid level control valve.

[0009] Preferably, the LV1 control valve, LV2 control valve, pressure relief valve, HV1 valve, HV2 valve, HV3 valve, HV4 valve, HV5 valve, HV6 valve, HV7 valve, and HV8 valve are all electrically controlled valves with communication connections. The system also includes a DCS system connected to remote pressure gauge PZT1, remote pressure gauge PZT2, remote flow meter FI, and each valve.

[0010] This invention discloses a process method for reducing the number of mechanical cleaning cycles required for easily clogged valves. The process method includes:

[0011] 1) Under normal operating conditions, open valves HV1 and HV2 in line A, and close valves HV3 and HV4. The level control valve is connected in series with the level control valve via LV1 to achieve automatic level control. Under normal operating conditions, the level in the reactor is controlled at 50±5%, the opening of the LV1 control valve is 55±3%, and the reactor pressure is pressure PI, which can be set according to actual needs. The reactor pressure is set by a remote pressure sensor inside the reactor. Close valves HV5, HV6, HV7, and HV8 in line B, and open valve LV2 as a backup switching line.

[0012] 2) When the opening of the LV1 control valve is increased to more than 58%, the reactor liquid level continues to rise above the preset value, and the value of the remote pressure gauge PZT1 drops, an alarm is triggered, a delay of 15 seconds is set, and the system switches to line B.

[0013] When putting Line B into operation, first close the LV2 control valve to 0%, open the HV5 and HV6 valves, confirm that the HV5 and HV6 valves are open, slowly open the LV2 control valve, and set the opening degree OP at 0.2% / time, and set the ramp abnormal alarm according to actual needs.

[0014] 3) Disconnect line A: Under normal overload conditions at line B, the liquid level in the reactor drops. Gradually close the LV1 control valve until the opening OP of the LV1 control valve and the LV2 control valve are consistent. Then, connect the LV2 control valve in series with the liquid level control valve in the reactor. After a 10-second delay, once the liquid level in the reactor stabilizes, disconnect the LV1 control valve from the liquid level control valve in series. Slowly close the LV1 control valve at an opening OP of 0.2% per cycle. Set an abnormal ramp alarm as needed until the LV1 control valve is closed to 0%.

[0015] 4) When the LV1 control valve is closed to 0%, the reaction liquid level in the reactor does not rise, and the opening degree OP of the LV2 control valve is the same as the opening degree OP of the LV1 control valve, confirm that line B is in normal operation.

[0016] 5) Isolate line A: Close valves HV1 and HV2;

[0017] 6) Confirm the pressure and temperature of the hot solvent in the hot solvent recovery tank. If the pressure and temperature of the hot solvent recovery tank reach the preset requirement value, perform the first stage of depressurization: open the HV4 valve to 25%, open the LV1 control valve, and depressurize the pipeline pressure of the pressure relief valve equipped with the remote pressure gauge PZT1 to 30% of the normal pipeline pressure; in the second stage of depressurization, depressurize the pipeline pressure of the pressure relief valve equipped with the remote pressure gauge PZT1 to the solvent recovery tank, close the HV4 valve, and the depressurization is complete.

[0018] 7) Intermittent hot flushing of line A: Open valve HV3 and observe whether the flow rate of the remote flow meter FI is normal. After the pressure rises to the preset hot flushing oil pressure, refer to step 6) for the pipeline depressurization process and repeat this flushing process 3 times.

[0019] 8) Continuous hot washing of line A: Open valves HV3 and HV4, confirm that the remote flow meter FI is normal, and continuously flush with hot solvent for 20 minutes. If the hot solvent flow rate remains normal, it is determined that the hot washing of each valve in line A is complete.

[0020] 9) Close valve HV4 and wait for the pressure on remote pressure gauge PZT1 to reach the system pressure during normal production. Then close valve HV3. At this time, line A will be ready for normal standby after hot washing.

[0021] Preferably, if line B malfunctions, steps 1) to 9) are used in the same way to switch from line B to line A.

[0022] Beneficial effects: By anticipating valve blockage problems in advance, this invention improves the automation level of the equipment, reduces the number of times valves need to be mechanically opened for maintenance and clearing blockages, and reduces the risk of valve damage. This optimization can effectively avoid system malfunctions and forced shutdowns due to blockage of regulating valves, thus ensuring long-term production of the equipment. Attached Figure Description

[0023] Figure 1 This is a block diagram illustrating the system principle of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0025] This invention adds a hot solvent backwashing line (hot solvent flushing system) before the regulating valve, and periodically switches the regulating valve to perform hot solvent backwashing according to the opening degree of the regulating valve, so as to prevent the regulating valve from being blocked, increasing the maintenance and repair work of the equipment, and affecting the long-term operation of the equipment.

[0026] The design incorporates a hot solvent backwashing program control for easily clogged regulating valves. Based on the valve opening during actual production, the existing DCS system enables automatic backwashing of all valves discharging from the reactor.

[0027] DCS system: Distributed control system is a new generation of instrument control system based on microprocessors, which adopts the design principles of decentralized control functions, centralized display and operation, and taking into account both decentralized autonomy and comprehensive coordination.

[0028] like Figure 1 The diagram shows a specific embodiment of a system and process for reducing the number of times a valve prone to clogging needs to be mechanically cleaned. The system includes two pipelines, A and B, which are laid in a pipeline manner. The left and right ends of the A pipeline are connected to the reactor and the downstream system, respectively. The A pipeline is sequentially connected to a valve HV1, a control valve LV1, a pressure relief valve equipped with a remote pressure gauge PZT1, and a valve HV2. A hot solvent flushing system is connected between the pressure relief valve equipped with the remote pressure gauge PZT1 and the HV2 valve.

[0029] One end of line B is connected to the inlet of valve HV1, and the other end of line B is connected to the outlet of valve HV2. Line B is sequentially connected to valve HV5, pressure relief valve equipped with remote pressure gauge PZT2, control valve LV2, and valve HV6. Line A between valve HV1 and control valve LV1 is connected to pipeline No. 1 with valve HV4. Line B between valve HV5 and control valve LV2 is connected to pipeline No. 2 with valve HV8. Pipelines No. 1 and No. 2 converge and are connected to a solvent recovery tank.

[0030] The hot solvent flushing system includes a hot solvent recovery tank connected to pipeline number 3, which is equipped with a remote flow meter FI. The hot solvent flushing system is connected to line A via pipeline number 3. Pipeline number 3 is also connected to valve number HV3. The inlet of valve number HV3 is connected to pipeline number 4, which is connected to line B between a pressure relief valve equipped with a remote pressure gauge PZT2 and valve number HV6. Pipeline number 4 is also connected to valve number HV7. The reactor contains level control valves, and control valves LV1 and LV2 can be cascaded with them. All valves—LV1, LV2, pressure relief valve, HV1, HV2, HV3, HV4, HV5, HV6, HV7, and HV8—are electrically controlled valves with communication connections. The system also includes a DCS system connected to remote pressure gauges PZT1 and PZT2, the remote flow meter FI, and all valves.

[0031] Using the system for reducing the number of mechanical cleaning cycles for easily clogged valves described in this application, a specific

[0032] The process methods include:

[0033] 1) Under normal operating conditions, open valves HV1 and HV2 in line A, and close valves HV3 and HV4. The level control valve is connected in series with the level control valve via LV1 to achieve automatic level control. Under normal operating conditions, the level in the reactor is controlled at 50±5%, the opening of the LV1 control valve is 55±3%, and the reactor pressure is pressure PI, which can be set according to actual needs. The reactor pressure is set by a remote pressure sensor inside the reactor. Close valves HV5, HV6, HV7, and HV8 in line B, and open valve LV2 as a backup switching line.

[0034] 2) When the LV1 control valve is opened to more than 65% (which can be set according to actual conditions, or triggered when the liquid level continues to drop below the minimum set value), the reactor liquid level continues to rise above the preset value of 60%, and the value of the remote pressure gauge PZT1 drops, an alarm is triggered, with a set delay of 15 seconds, and then the switch to line B.

[0035] When putting Line B into operation, first close the LV2 control valve to 0%, open the HV5 and HV6 valves, confirm that the HV5 and HV6 valves are open, slowly open the LV2 control valve, and set the opening degree OP at 0.2% / time. Set the ramp abnormal alarm according to actual needs (set the ramp speed, which can be adjusted according to the actual situation, slowly control the valve opening speed, and set the ramp abnormal alarm).

[0036] 3) Disconnect line A: Under normal overload conditions at line B, the liquid level in the reactor drops. Gradually close the LV1 control valve until the opening OP of the LV1 control valve and the LV2 control valve are consistent. Then, connect the LV2 control valve in series with the liquid level control valve in the reactor. After a 10-second delay, once the liquid level in the reactor stabilizes, disconnect the LV1 control valve from the liquid level control valve in series. Slowly close the LV1 control valve at an opening OP of 0.2% per cycle. Set an abnormal ramp alarm as needed (set the ramp speed, which is adjustable according to the actual situation; slowly control the valve closing speed and set an abnormal ramp alarm) until the LV1 control valve is closed to 0%.

[0037] 4) When the LV1 control valve is closed to 0%, the reaction liquid level in the reactor does not rise, and the opening degree OP of the LV2 control valve is the same as the opening degree OP of the LV1 control valve, confirm that line B is in normal operation.

[0038] 5) Isolate line A: Close valves HV1 and HV2;

[0039] 6) Confirm the pressure and temperature of the hot solvent in the hot solvent recovery tank. If the pressure and temperature of the hot solvent recovery tank reach the preset requirement value, perform the first stage of depressurization: open valve HV4 to 25%, open valve LV1, and depressurize the pipeline pressure of the pressure relief valve equipped with remote pressure gauge PZT1 to 30% of the normal pipeline pressure; in the second stage of depressurization, depressurize the pipeline pressure of the pressure relief valve equipped with remote pressure gauge PZT1 to the solvent recovery tank, close valve HV4, and the depressurization is complete.

[0040] 7) Intermittent hot flushing of line A: Open valve HV3 and observe whether the flow rate of the remote flow meter FI is normal. After the pressure rises to the preset hot flushing oil pressure, refer to step 6) for the pipeline depressurization process and repeat this flushing process 3 times (the number of times is adjustable).

[0041] 8) Continuous hot washing of line A: Open valves HV3 and HV4, confirm that the remote flow meter FI is normal, and continuously flush with hot solvent for 20 minutes (time is adjustable). If the hot solvent flow rate remains normal, it is determined that the hot washing of each valve in line A is complete.

[0042] 9) Close valve HV4 and wait for the pressure on remote pressure gauge PZT1 to reach the system pressure during normal production. Then close valve HV3. At this time, line A will be ready for normal standby after hot washing.

[0043] If line B is running abnormally, use the same method as steps 1)-9) to switch back to line A.

[0044] In this application, each valve is preferably configured as an electrically controlled valve, which is centrally regulated by a DCS system.

[0045] Finally, it should be noted that the present invention is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A system for reducing the number of mechanical cleaning cycles required for easily clogged valves, characterized in that: It includes A line and B line laid in the form of pipelines. The left and right ends of the A line are respectively connected to the reactor and the downstream system. The A line is connected in sequence to the HV1 valve, the LV1 control valve, the pressure relief valve equipped with the remote pressure gauge PZT1, and the HV2 valve. The A line between the pressure relief valve equipped with the remote pressure gauge PZT1 and the HV2 valve is connected to a hot solvent flushing system. One end of line B is connected to the inlet of valve HV1, and the other end of line B is connected to the outlet of valve HV2. Line B is sequentially connected to valve HV5, pressure relief valve equipped with remote pressure gauge PZT2, control valve LV2, and valve HV6. Line A between valve HV1 and control valve LV1 is connected to pipeline No. 1 with valve HV4. Line B between valve HV5 and control valve LV2 is connected to pipeline No. 2 with valve HV8. Pipelines No. 1 and No. 2 converge and are connected to a solvent recovery tank. The hot solvent flushing system includes a hot solvent recovery tank, which is connected to pipeline No. 3 equipped with a remote flow meter FI. The hot solvent flushing system is connected to line A via pipeline No.

3. An HV3 valve is also connected to pipeline No.

3. The inlet of the HV3 valve is connected to pipeline No.

4. Pipeline No. 4 is connected to line B between a pressure relief valve equipped with a remote pressure gauge PZT2 and valve No.

6. An HV7 valve is connected to pipeline No.

4. A liquid level control valve is provided in the reactor. Both LV1 and LV2 control valves can be cascaded with the liquid level control valve.

2. The system for reducing the number of mechanical cleaning operations for easily clogged valves according to claim 1, characterized in that: The LV1 control valve, LV2 control valve, pressure relief valve, HV1 valve, HV2 valve, HV3 valve, HV4 valve, HV5 valve, HV6 valve, HV7 valve, and HV8 valve are all electrically controlled valves with communication connections. It also includes a DCS system connected to remote pressure gauge PZT1, remote pressure gauge PZT2, remote flow meter FI, and each valve.

3. A process method for reducing the number of mechanical cleaning cycles required for easily clogged valves, characterized in that... The process includes: 1) Under normal operating conditions, open valves HV1 and HV2 in line A, and close valves HV3 and HV4. The level control valve is connected in series with the level control valve via LV1 to achieve automatic level control. Under normal operating conditions, the level in the reactor is controlled at 50±5%, and the opening of the LV1 control valve is 55±3%. Close valves HV5, HV6, HV7, and HV8 in line B, and open valve LV2 as a backup switching line. 2) When the opening of the LV1 control valve is increased to more than 58%, the reactor liquid level continues to rise above the preset value, and the value of the remote pressure gauge PZT1 drops, an alarm is triggered, a delay of 15 seconds is set, and the system switches to line B. When putting Line B into operation, first close the LV2 control valve to 0%, open the HV5 and HV6 valves, confirm that the HV5 and HV6 valves are open, slowly open the LV2 control valve, and set the opening degree OP at 0.2% / time, and set the ramp abnormal alarm according to actual needs. 3) Disconnect line A: Under normal overload conditions at line B, the liquid level in the reactor drops. Gradually close the LV1 control valve until the opening OP of the LV1 control valve and the LV2 control valve are consistent. Then, connect the LV2 control valve in series with the liquid level control valve in the reactor. After a 10-second delay, once the liquid level in the reactor stabilizes, disconnect the LV1 control valve from the liquid level control valve in series. Slowly close the LV1 control valve at an opening OP of 0.2% per cycle. Set an abnormal ramp alarm as needed until the LV1 control valve is closed to 0%. 4) When the LV1 control valve is closed to 0%, the reaction liquid level in the reactor does not rise, and the opening degree OP of the LV2 control valve is the same as the opening degree OP of the LV1 control valve, confirm that line B is in normal operation. 5) Isolate line A: Close valves HV1 and HV2; 6) Confirm the pressure and temperature of the hot solvent in the hot solvent recovery tank. If the pressure and temperature of the hot solvent recovery tank reach the preset requirement value, perform the first stage of depressurization: open the HV4 valve to 25%, open the LV1 control valve, and depressurize the pipeline pressure of the pressure relief valve equipped with the remote pressure gauge PZT1 to 30% of the normal pipeline pressure; in the second stage of depressurization, depressurize the pipeline pressure of the pressure relief valve equipped with the remote pressure gauge PZT1 to the solvent recovery tank, close the HV4 valve, and the depressurization is complete. 7) Intermittent hot flushing of line A: Open valve HV3 and observe whether the flow rate of the remote flow meter FI is normal. After the pressure rises to the preset hot flushing oil pressure, refer to step 6) for the pipeline depressurization process and repeat this flushing process 3 times. 8) Continuous hot washing of line A: Open valves HV3 and HV4, confirm that the remote flow meter FI is normal, and continuously flush with hot solvent for 20 minutes. If the hot solvent flow rate remains normal, it is determined that the hot washing of each valve in line A is complete. 9) Close valve HV4 and wait for the pressure on remote pressure gauge PZT1 to reach the system pressure during normal production. Then close valve HV3. At this time, line A will be ready for normal standby after hot washing.

4. The process method for reducing the number of mechanical cleaning cycles for easily clogged valves according to claim 3, characterized in that: If line B is running abnormally, use the same method as steps 1)-9) to switch back to line A.

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