A control method for a spray system of a degassing and defoaming tower in carbon fiber production

Abstract

The present invention relates to a control method for a spray system of a de-singling and de-bubbling tower in carbon fiber production, which solves the technical problem that the existing de-singling and de-bubbling tower spray system lacks an automatic control system, and is provided with a spray device and a spray control system, the spray device is electrically connected to the spray control system, and the spray device is provided with an inner ring spray device and an outer ring spray device; the spray device is provided with a spray head and a control valve, and the control valve is electrically connected to the spray control system; the spray control system is provided with a pressure transmitter, a temperature transmitter, a distributed control module, a batch controller, a safety instrument system and an online analyzer, the distributed control module is connected to the batch controller through a redundant Ethernet, the safety instrument system is connected to the distributed control module through a redundant Ethernet; the online analyzer is connected to the safety instrument system; the pressure transmitter, the temperature transmitter are connected to the safety instrument system, and the distributed control module is connected. The present invention can be widely used in the carbon fiber production process.

Description

Technical Field

[0001] The invention relates to the field of carbon fiber production, in particular to a control method for a spray system of a de-singling and de-bubbling tower in carbon fiber production. Background Art

[0002] Excellent carbon fiber requires excellent PAN stock solution. The stripping tower is an important link in the production of excellent raw yarn; it is a very important link in the production of polyacrylonitrile. The stripping effect of the stripping tower directly affects the key performance of polyacrylonitrile.

[0003] The energy consumption of the stripping tower is also an important goal for factories to save energy and reduce product costs. The existing spray system control does not achieve a good control effect on a stripping tower system with slow change, large lag and constantly changing delay time constant. It has defects in control margin and energy saving, which increases the production cost of polyacrylonitrile. Summary of the invention

[0004] In order to solve the technical problem that the existing degassing and degassing tower spray system lacks an automatic control system, the present invention provides a control method for the degassing and degassing tower spray system in carbon fiber production that is not directly participated in and can be automatically operated.

[0005] The invention provides a spray system for a de-singling and de-bubbling tower in carbon fiber production, which is provided with a spray device and a spray control system, wherein the spray device is electrically connected to the spray control system, and the spray device is provided with an inner ring spray device and an outer ring spray device; the spray device is provided with a spray head and a control valve, and the control valve is electrically connected to the spray control system; the spray control system is provided with a pressure transmitter, a temperature transmitter, a distributed control module, a batch controller, a safety instrument system and an online analyzer, wherein the distributed control module is connected to the batch controller through a redundant Ethernet, and the safety instrument system is connected to the distributed control module through a redundant Ethernet; the online analyzer is connected to the safety instrument system; the pressure transmitter and the temperature transmitter are respectively connected to the safety instrument system and the distributed control module through an instrument intrinsically safe cable.

[0006] Preferably, the control valve is provided with an automatic control valve which is independently controlled by a double solenoid valve in series control. The nominal diameter of the spray control valve is DN8mm, and the flow rate is not more than 0.01m 3 / h, the full stroke time is less than 1s, the control valve trigger opening time is: 5 to 30s; the distance between the control valve and the nozzle is not more than 1m.

[0007] Preferably, the inner ring spray device is provided with 8 nozzles forming a circle, and the outer ring spray device is provided with 16 nozzles forming a circle.

[0008] The present invention also provides a control method for a spray system of a degassing tower in carbon fiber production, which adopts the spray system of a degassing tower in carbon fiber production, and the steps include:

[0009] Step 1, start the sprinkler system and initialize the system;

[0010] Step 2, detecting a reset signal of a safety instrument system interlock solenoid valve;

[0011] Step 3, reset all instruments and close the valve solenoid valve;

[0012] Step 4: Check whether the temperature and pressure signals in the tower meet the operating conditions. If they do not meet the requirements, the system will pop up an alarm and stop the sequential control operation. When the problem is solved and the conditions are met, the system will be reset and restarted.

[0013] Step 5: Logically determine whether all signals are in the correct position. If the requirements are not met, the system will pop up an alarm and stop the sequential control operation. When the problem is solved and the conditions are met, the system will reset and restart the operation.

[0014] Step 6, open the automatic control valve of the first nozzle, check whether the valve position feedback is normal, and repeat step 5;

[0015] Step 7, timing according to the batch processing sequential control logic setting value;

[0016] Step 8, open the next automatic control valve to detect whether the valve position feedback is normal, and at the same time delay closing the previous automatic control valve to detect whether its valve position feedback is normal;

[0017] Step 9, gradually opening and closing the required number of automatic control valves using the same process logic as step 8;

[0018] Step 10, after completing one cycle, return to the first valve to continue the cycle;

[0019] Step 11: After the spraying index reaches the standard, stop the spraying system through the DCS operation button.

[0020] Preferably, when the batch controller of step 7 is started, the actual measured value of the tower top pressure transmitter must be greater than 0.5 KPa.

[0021] Preferably, in step 8, the previous automatic control valve is closed with a delay of 1 to 3 seconds.

[0022] Preferably, the spray index reaches the standard when the online analyzer detects that the process index of the polymerization liquid reaches the numerical requirement, the batch controller of the control system issues a stop command, and the spray system stops running.

[0023] The beneficial effects of the present invention are:

[0024] The present invention uses the batch controller (BATCH controller) in the DELTAV system of the Emerson DCS series to call, and sets and calls through pre-programmed logical setting values ​​to control the interval time, so as to achieve slow change in the spraying process; through the actuator matched with the device, its continuity is achieved; at the same time, the control system is used to achieve its stability. The slow change, continuity and stability of the polymer solution are ensured, the automation of the entire control system is realized, and a fully automatic control process with simple operation and no one on site is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a control flow diagram of the present invention;

[0026] Figure 2 Schematic diagram of valve distribution of the spray device of the present invention;

[0027] Figure 3 It is a structural schematic diagram of the valve control device of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can easily implement the present invention.

[0029] Example:

[0030] like Figure 1-2 As shown, the spray control system of the present invention is realized by calling batch sequential control logic (BATCH (1)) or batch sequential control logic (BATCH (2)), according to the production requirements. Figure 2 When spraying the inner ring, BATCH⑴ can be used to achieve it, the steps are as follows:

[0031] ①Start the spray system batch processing BATCH⑴, the system is initialized and meets the conditions;

[0032] ② Detect the reset signal of the interlock solenoid valve of the safety instrument system (SIS system);

[0033] ③ Reset all instruments and close 24 valve solenoid valves;

[0034] ④ Check whether the temperature and pressure signals in the tower meet the operating conditions. If they do not meet the requirements, the system will pop up an alarm prompt and stop the sequential control operation; when the problem is solved and the conditions are met, the system will be reset and restarted;

[0035] ⑤Logically determine whether all signals are in the correct position; if the requirements are not met, the system will pop up an alarm prompt and stop the sequential control operation; when the problem is solved and the conditions are met, the system will reset and restart the operation;

[0036] ⑥Open the automatic control valve SV1 and check whether the valve position feedback is normal; same as step ⑤;

[0037] ⑦ Count down according to the setting value of BATCH⑴;

[0038] ⑧Open the automatic control valve SV2 to check whether the valve position feedback is normal, and at the same time delay the closing of the automatic control valve SV1 to check whether its valve position feedback is normal;

[0039] ⑨Open and close the automatic control valve step by step using the same process logic: SV3~SV4~SV5~SV6~SV7~SV8....SV1;

[0040] ⑩After completing a cycle, return to the first valve to continue the cycle; when the spraying index requirements are met, stop the spraying system through the DCS operation button.

[0041] 2. According to the needs of production operation, use Figure 2 When the inner and outer rings are sprayed at the same time, BATCH⑵ can be used to achieve this.

[0042] ①Start the spray system BATCH ⑵, the system is initialized and meets the conditions;

[0043] ② Detect the reset signal of SIS interlock solenoid valve;

[0044] ③ Reset all instruments and close 24 valve solenoid valves;

[0045] ④ Check whether the temperature and pressure signals in the tower meet the operating conditions. If they do not meet the requirements, the system will pop up an alarm prompt and stop the sequential control operation; when the problem is solved and the conditions are met, the system will be reset and restarted;

[0046] ⑤Logically determine whether all signals are in the correct position; if the requirements are not met, the system will pop up an alarm prompt and stop the sequential control operation; when the problem is solved and the conditions are met, the system will reset and restart the operation;

[0047] ⑥Open the automatic control valve SV1 and check whether the valve position feedback is normal; same as step ⑤;

[0048] ⑦ Count down according to the BATCH ⑵ setting value;

[0049] ⑧Open the automatic control valve SV2 to check whether the valve position feedback is normal, and at the same time delay the closing of the automatic control valve SV1 to check whether its valve position feedback is normal; the same as step ⑤;

[0050] ⑨ Use the same process logic to gradually open and close the automatic control valve: SV3~SV4~SV5~SV6~SV7~SV8~SV9~SV10~SV11~SV12~SV13~SV14~SV15~SV16~SV17~SV18~SV19~SV20~SV21~SV22~SV23~SV24....SV1;

[0051] ⑩After completing a cycle, return to the first valve to continue the cycle; when the spraying index requirements are met, stop the spraying system through the DCS operation button.

[0052] Attached Figure 2 This is the distribution diagram of the spray device, which is evenly distributed in inner and outer rings:

[0053] ① Inner ring spray corresponds to batch processing BATCH⑴ control strategy;

[0054] ②Inner and outer ring spraying corresponds to batch processing BATCH ⑵ control strategy;

[0055] ③ The outer ring spray corresponds to the batch processing BATCH⑶ control strategy, which belongs to the third option.

[0056] 4. If a fault occurs in the sprinkler system, the sprinkler control system will issue a fault alarm, and a fault step event will pop up and the batch processing BATCH step sequence will be suspended. After the fault is handled, click the fault reset button on the operation console and the batch processing BATCH step sequence will continue to run.

[0057] Among them, the main types of faults are:

[0058] ① Distributed DCS control system failure;

[0059] a. Hardware failure;

[0060] b. Software failure;

[0061] ② Failure of on-site automatic control equipment;

[0062] a. Automatic control valve failure;

[0063] b. Temperature and pressure transmitter failure;

[0064] ③ False fault signal.

[0065] 5. When a sudden power outage occurs in the production unit, the safety instrument SIS system will send an interlock signal, and the distributed DCS control system will interrupt and stop the batch spray program.

[0066] 6. The on-site automatic control valve of the stripping tower is controlled by double solenoid valves, one of which is controlled by the safety instrument SIS and the other is controlled by the distributed DCS control system.

[0067] 7. If Figure 3 As shown, the high-precision pressure and temperature transmitter installed on the stripping tower enters the distributed DCS control module through 4-20 mA, and is collected and digitally processed by the distributed DCS controller to output the corresponding pressure and temperature values.

[0068] 8. The control system and the on-site automatic control equipment are connected by hard-wire intrinsically safe flame-retardant shielded cables; the control system includes: DCS system and SIS system, and the on-site automatic control equipment includes: solenoid valves, transmitters, online analyzers, etc. Some pressure transmitters, some temperature transmitters and online analyzers are connected to the safety instrument system through instrument intrinsically safe cables; another part of the pressure transmitter and another part of the temperature transmitter are connected to the distributed control module through instrument intrinsically safe cables; the safety instrument system is connected to the distributed control module through redundant Ethernet.

[0069] 9. Signal types:

[0070] a. Using the DInamur signal of the NAMUR (German Measurement and Control Standards Committee) standard: current range: 1.2mA ~ 2.1mA; the calibration value is 1.55mA, when the current changes from low to high or equals 1.75mA, an output signal change (from 0 to 1 or from ON to OFF) will be generated; when the current changes from high to low or is lower than 1.55mA, an output signal change (from 1 to 0, or from ON to OFF) will be generated;

[0071] b.DO switch signal: output DC voltage: 24V.

[0072] c.Analog signal: 4-20mA.

[0073] The spray control valve body and valve core are all made of 316SS, and the packing material is polytetrafluoroethylene PTFE to avoid corrosion from the medium dimethyl sulfoxide (DMSO).

[0074] The valve leakage level requirement is not lower than Level VI.

[0075] The control system power supply adopts a dedicated industrial UPS, which provides no less than 1 hour to ensure the stability of the control system.

[0076] like Figure 3 As shown, the automatic control valve is controlled by dual solenoid valves, and the solenoid valves controlled by the SIS system and the DCS system are independent of each other; the two-way solenoid valve gas circuit is connected in series to ensure that the valve will be closed if any one of the circuits fails or a command is issued, thus ensuring the safety of on-site equipment and personnel.

[0077] When the batch controller is started, the measured value of the tower top pressure transmitter PT-001 must be greater than 0.5KPa. Nominal diameter of the spray control valve: DN8mm, flow rate not greater than 0.01m 3 / h, the full stroke time is less than 1S. The trigger opening time of each control valve is: 5~30s. When the control valve SVn is closed, the batch controller opens the valve SVn-1 1~3s in advance, and opens the previous valve 1~3s in advance to meet the requirement of continuous flow of the medium. When the online analyzer installed at the bottom of the stripping tower sends a signal that the process index value of the polymerization liquid meets the requirement, the control system batch controller detects the value and issues a stop command, and the spray system stops running. The distance between the control valve and the nozzle is not more than 1m.

[0078] The above description is only for the preferred embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the scope of the claims of the present invention shall be within the scope of protection of the present invention.

Claims

1. A control method for a spray system of a degassing tower in carbon fiber production, which adopts a spray device and a spray control system, wherein the spray device is electrically connected to the spray control system, and the spray device is provided with an inner ring spray device and an outer ring spray device; the spray device is provided with a nozzle and a control valve, and the control valve is electrically connected to the spray control system; the spray control system is provided with a pressure transmitter, a temperature transmitter, a distributed control module, a batch controller, a safety instrument system and an online analyzer, wherein the distributed control module is connected to the batch controller through a redundant Ethernet, and the safety instrument system is connected to the distributed control module through a redundant Ethernet; the online analyzer is connected to the safety instrument system; the pressure transmitter and the temperature transmitter are respectively connected to the safety instrument system and the distributed control module through an instrument intrinsically safe cable, and the characteristic is that: The steps include: Step 1, start the sprinkler system and initialize the system; Step 2, detecting a reset signal of a safety instrument system interlock solenoid valve; Step 3, reset all instruments and close the valve solenoid valve; Step 4: Check whether the temperature and pressure signals in the tower meet the operating conditions. If they do not meet the requirements, the system will pop up an alarm and stop the sequential control operation. When the problem is solved and the conditions are met, the system will be reset and restarted. Step 5: Logically determine whether all signals are in the correct position. If the requirements are not met, the system will pop up an alarm and stop the sequential control operation. When the problem is solved and the conditions are met, the system will reset and restart the operation. Step 6, open the automatic control valve of the first nozzle, check whether the valve position feedback is normal, and repeat step 5; Step 7, timing according to the batch processing sequential control logic setting value; Step 8, open the next automatic control valve to detect whether the valve position feedback is normal, and at the same time delay closing the previous automatic control valve to detect whether its valve position feedback is normal; Step 9, gradually opening and closing the required number of automatic control valves using the same process logic as step 8; Step 10, after completing one cycle, return to the first valve to continue the cycle; Step 11: After the spraying index reaches the standard, stop the spraying system through the DCS operation button.

2. The control method of the spray system of the degassing and degassing tower in the production of carbon fiber according to claim 1, characterized in that: When the batch controller of step 7 is started, the actual measured value of the tower top pressure transmitter must be greater than 0.5 KPa.

3. The control method of the spray system of the degassing and degassing tower in the production of carbon fiber according to claim 1, characterized in that: In step 8, the previous automatic control valve is closed with a delay of 1 to 3 seconds.

4. The control method of the spray system of the degassing and degassing tower in the production of carbon fiber according to claim 1, characterized in that: The spray index reaches the standard when the online analyzer detects that the process index of the polymerization liquid reaches the numerical requirement, the batch controller of the control system issues a stop command, and the spray system stops running.

Images