Control system and method for switching condenser in phthalic anhydride production

Abstract

The invention provides a control system and method for switching condensers in phthalic anhydride production, and belongs to the technical field of control in the petrochemical industry. The control system for switching the condenser in phthalic anhydride production comprises a distributed control system, a timing piece, a plurality of sensors, a plurality of cold boxes, a plurality of pipelines and a plurality of valves. The multiple sensors collect the real-time process state, and the distributed control system controls the opening and closing time, the opening and closing sequence and the opening and closing degree of the multiple valves according to the real-time process state so as to control cold and hot oil inlet and outlet, raw material inlet and outlet and cold box switching of the switching condenser. Compared with semi-automatic control or pure manual control of a switching condenser control position in the prior art, full automation is achieved in the production process of switching the condenser, operators only need to click start and stop buttons, full-automatic production is achieved in the middle, operation risks and personnel loads are greatly reduced, and much manpower is saved.

Description

Technical Field

[0001] The present invention relates to the field of control technology in the petrochemical industry, and in particular to a control system and method for a phthalic anhydride production switching condenser. Background Art

[0002] There are two mainstream methods for producing phthalic anhydride in the chemical industry, one is the naphthalene process phthalic anhydride, and the other is the ortho-process phthalic anhydride. The production processes and raw materials of the two phthalic anhydride are different, but both methods require the use of a switching condenser to separate the phthalic anhydride and by-products in the raw gas during the production process, so the switching condenser is a very important equipment in the phthalic anhydride production process.

[0003] The existing control methods for switching condensers are: one is to let the operator closely monitor the temperature information and time information of the condenser, and manually open and close the cold and hot oil inlet and outlet valves and the raw material inlet and outlet valves to condense phthalic anhydride; the second is to build a control program through a logic gate circuit to control the solenoid valve, manually control the pneumatic regulating valve of the raw gas, and semi-automatically control the production of phthalic anhydride. The first method of the above methods requires high operator proficiency, large temperature control errors, heavy workload for operators, and there is a possibility of misoperation leading to product waste or even detonation of raw gas to damage the condenser itself. The second method has the disadvantages of being difficult to apply to large-scale production lines, extremely difficult to debug, inconvenient to modify process parameters later, high technical requirements for maintenance personnel, and no relevant control of hot gas raw material valves. Summary of the invention

[0004] In order to solve the above problems, the embodiments of the present application provide a control system and method for a switching condenser in phthalic anhydride production.

[0005] In the first aspect, the present application provides a control system for a phthalic anhydride production switching condenser, including a distributed control system, a timing component, multiple sensors, multiple cold boxes arranged in the switching condenser, multiple pipes connected to the multiple cold boxes, and multiple valves arranged on the multiple pipes, wherein the multiple sensors are used to collect real-time process status; the timing component is used to perform timing when a preset valve is opened to obtain a timing status, and the real-time process status includes a first real-time temperature of the oil in the cold box and a first feedback status of multiple valves; the distributed control system includes a control logic program; the distributed control system controls the multiple cold boxes to execute corresponding working modes in sequence according to the control logic program, and when the preset cold box executes the preset working mode, the distributed control system controls the valve corresponding to the cold box to execute the corresponding action according to the first real-time temperature or the first feedback status or the timing status of the timing component.

[0006] Preferably, the working modes of the cold box include three working modes: hot melting, precooling, and condensing. The distributed control system controls a cold box to perform the three working modes of hot melting, precooling, and condensing in sequence.

[0007] Preferably, the multiple valves include a hot gas raw material inlet valve corresponding to each cold box, a hot and cold oil inlet three-way valve corresponding to each cold box, a hot and cold oil outlet three-way valve corresponding to each cold box, an oil cooling bypass valve corresponding to each cold box, an exhaust valve corresponding to each cold box, and an emergency nitrogen fire extinguishing valve corresponding to each cold box.

[0008] Preferably, the distributed control system includes a control module, a processing module for performing logical processing on real-time process status, and a programming module that can input a control logic program. The control module is used to output high and low level signals and / or industrial current output signals to corresponding valves according to the control logic program. The control logic program includes a core program and auxiliary programs. The core program includes a hot and cold oil inlet and outlet valve control program, a raw material inlet and outlet valve control program, and a plurality of cold box switching programs. The auxiliary programs include an interlocking protection program and a timing program. The core program is written in ST language, and the auxiliary program is written in FBD language.

[0009] Preferably, the timing component includes a hot oil outlet timer. When a cold box is in hot melt working mode, the distributed control system controls the hot and cold oil inlet three-way valve corresponding to the cold box to open to input hot oil into the cold box and controls the hot oil outlet timer to start timing. The distributed control system controls the hot and cold oil outlet three-way valve corresponding to the cold box to open when the first real-time temperature corresponding to the cold box is not less than the first preset temperature or the timing state of the hot oil outlet timer is at the end.

[0010] Preferably, the timing component also includes a cold oil outlet timer. When a cold box is in pre-cooling working mode, the distributed control system controls the cold and hot oil inlet three-way valve corresponding to the cold box to close and controls the cold oil outlet timer to start timing. When the first real-time temperature corresponding to the cold box is not greater than the second preset value or the timing state of the cold oil outlet timer is end, the cold and hot oil outlet three-way valve corresponding to the cold box is controlled to close.

[0011] Preferably, when a cold box is performing a condensing working mode, the distributed control system controls the exhaust valve and the oil cooling bypass valve corresponding to the cold box to open, and when obtaining a first feedback state signal of the exhaust valve and a first real-time temperature of the cold box is not greater than a third preset value, the distributed control system controls the hot gas raw material regulating valve corresponding to the cold box to switch to a first preset state, and the distributed control system also controls the hot gas raw material regulating valve to adjust to a first preset opening at intervals of a first preset time to adjust the hot gas raw material regulating valve from an initial opening to a target opening.

[0012] In a second aspect, an embodiment of the present application provides a method for controlling a switching condenser for producing phthalic anhydride, comprising the following steps: S1: Distributed control system obtains control logic program; S2: The distributed control system controls multiple cold boxes to execute corresponding working modes in sequence according to the control logic program; Multiple sensors collect real-time process status, and the timing component performs timing when the corresponding valve is opened to obtain the timing status. When the preset cold box executes the preset working mode, the distributed control system controls the valve corresponding to the cold box to perform corresponding actions according to the first real-time temperature or the first feedback status or the timing status of the timing component.

[0013] In a third aspect, an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method provided in a possible implementation manner of the second aspect are implemented.

[0014] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method provided in a possible implementation manner of the second aspect.

[0015] The beneficial effects of the present invention are as follows: multiple sensors collect real-time process status, and the distributed control system controls the switching time, switching sequence, and switching degree of multiple valves according to the real-time process status, so as to control the switching of hot and cold oil in and out of the condenser, the raw material in and out, and the cold box switching. In the prior art, the switching condenser control position is semi-automatic control or purely manual control. The present application realizes full automation in the production process of switching condensers. The operator only needs to click the start and stop buttons, and the production is fully automated in the middle, which greatly reduces the operating risk and personnel burden, and saves a lot of manpower. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A principle block diagram of a control system for a phthalic anhydride production switching condenser provided in an embodiment of the present application; Figure 2 A schematic flow chart of a control method for a phthalic anhydride production switching condenser provided in an embodiment of the present application; Figure 3 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application; Figure 4 A schematic diagram of the process flow of four cold boxes in normal operation provided in the embodiment of the present application; Figure 5A principle block diagram of a sensor, a processing module, and a control module in a control system of a phthalic anhydride production switching condenser provided in an embodiment of the present application.

[0018] In the figure, 11-distributed control system, 111-control module, 112-processing module, 12-sensor, 13-valve. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0020] In the following introduction, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The following introduction provides multiple embodiments of the present application, and different embodiments can be replaced or combined, so the present application can also be considered to include all possible combinations of the same and / or different embodiments recorded. Therefore, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then the present application should also be considered to include embodiments containing one or more of all other possible combinations of A, B, C, and D, although the embodiment may not be clearly recorded in the following text.

[0021] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements described without departing from the scope of the present application. Various processes or components may be appropriately omitted, substituted or added to each example. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted or combined. In addition, features described in some examples may be combined in other examples.

[0022] See also Figure 1 , 5 . Figure 1 This is a principle block diagram of a control system for a phthalic anhydride production switching condenser provided in an embodiment of the present application. Figure 5The principle block diagram of the sensor, processing module and control module in the control system of a phthalic anhydride production switching condenser provided in the embodiment of the present application. In the embodiment of the present application, the system includes a distributed control system 11, a timing component, a plurality of sensors 12, a plurality of cold boxes arranged in the switching condenser, a plurality of pipes connected to the plurality of cold boxes, and a plurality of valves 13 arranged on the plurality of pipes, wherein the plurality of sensors 12 are used to collect real-time process status, and the timing component is used to perform timing when the preset valve is opened to obtain the timing status, and the real-time process status includes the first real-time temperature of the oil in the cold box and the first feedback status of the plurality of valves 13; the distributed control system 11 includes a control logic program; the distributed control system 11 controls the plurality of cold boxes to execute the corresponding working modes in sequence according to the control logic program, and when the preset cold box executes the preset working mode, the distributed control system 11 controls the valve corresponding to the cold box to execute the corresponding action according to the first real-time temperature or the first feedback status or the timing status of the timing component, so as to control the hot and cold oil in and out of the cold box of the switching condenser, the raw material in and out of the cold box, and the switching between different cold boxes.

[0023] In the embodiment of the present application, the distributed control system 11 is connected to multiple valves 13 and multiple sensors 12 respectively, and controls the hot and cold oil in and out of the entire switching condenser, the raw material in and out, and the cold box switching by switching the opening and closing time, opening and closing sequence, and opening and closing degree of multiple valves 13 of the cold box. Each stage is automatically processed and alarmed according to the set timing and conditions to achieve safe and reliable automatic control requirements. With the distributed control system 11 as a platform, multiple sensors 12 collect real-time process status. The platform obtains the operation control program after logical processing of the detected real-time process status signal, and automatically outputs the operation control program to the actuator, that is, outputs the operation control program to each valve 13. The operation control program can include a normal control program and an interlocking protection program in an emergency, so that the operation of the entire production device is more stable and reliable.

[0024] In one possible implementation, the working modes of the cold box include three working modes: hot melting, precooling, and condensing. The distributed control system 11 controls a cold box to perform the three working modes of hot melting, precooling, and condensing in sequence.

[0025] In one embodiment, the multiple valves include a hot gas raw material inlet valve corresponding to each cold box, a hot and cold oil inlet three-way valve corresponding to each cold box, a hot and cold oil outlet three-way valve corresponding to each cold box, an oil cooling bypass valve corresponding to each cold box, an exhaust valve corresponding to each cold box, and an emergency nitrogen fire extinguishing valve corresponding to each cold box.

[0026] In one possible implementation, the timing component includes a hot oil outlet timer. When a cold box is in hot melt working mode, the distributed control system 11 controls the hot and cold oil inlet three-way valve corresponding to the cold box to open to input hot oil into the cold box and controls the hot oil outlet timer to start timing. The distributed control system 11 controls the hot and cold oil outlet three-way valve corresponding to the cold box to open when the first real-time temperature corresponding to the cold box is not less than the first preset temperature or the timing state of the hot oil outlet timer is at the end.

[0027] In one embodiment, the timing component also includes a cold oil outlet timer. When a cold box is in pre-cooling working mode, the distributed control system 11 controls the cold and hot oil inlet three-way valve corresponding to the cold box to close and controls the cold oil outlet timer to start timing. When the first real-time temperature corresponding to the cold box is not greater than the second preset value or the timing state of the cold oil outlet timer is end, the cold and hot oil outlet three-way valve corresponding to the cold box is controlled to close.

[0028] In one feasible embodiment, when a cold box is performing a condensing working mode, the distributed control system 11 controls the exhaust valve and the oil cooling bypass valve respectively corresponding to the cold box to open, and when the distributed control system 11 obtains a first feedback state signal of the exhaust valve and the first real-time temperature of the cold box is not greater than a third preset value, controls the hot gas raw material regulating valve corresponding to the cold box to switch to a first preset state, and the distributed control system 11 controls the hot gas raw material regulating valve to adjust to a first preset opening at first preset time intervals to adjust the hot gas raw material regulating valve from an initial opening to a target opening.

[0029] In one embodiment, the distributed control system 11 includes a control module 111, a processing module 112 for logically processing real-time process status, and a programming module that can input a control logic program. The control module 111 is used to output high and low level signals and / or industrial current output signals to the corresponding valve 13 according to the control logic program. The control logic program includes a core program and an auxiliary program. The core program includes a hot and cold oil inlet and outlet valve control program, a raw material inlet and outlet valve control program, and a plurality of cold box switching programs. The auxiliary program includes an interlocking protection program and a timing program. The core program is written in ST language, and the auxiliary program is written in FBD language.

[0030] In the embodiment of the present application, the industrial current output signal can be a type II industrial current output signal, and the valve 13 can be an electric valve 13 or a regulating valve 13. The control module 111 sends high and low level signals and / or industrial current output signals corresponding to the control logic program, and sequentially controls the switching of multiple electric valves 13 and regulating valves 13 in the condenser. The programming code in the programming module adopts FBD (Function Block Diagram) programming language and ST language Structured Text, a structured text language, which makes the program highly readable, convenient to test and easy to maintain. The ST language encapsulates core programs such as hot and cold oil inlet and outlet valve control, raw material inlet and outlet valves, and multiple cold box switching. Auxiliary programs such as interlocking and timing are written in FBD language to realize program automatic control of switching condensers. The present application comprises a highly integrated and sufficiently secure core program written by ST program, an easily maintainable auxiliary program written by FBD program, a process data interface open to operators in real time through a host computer, and an automatic control program that automatically starts an interlock protection program under abnormal operating conditions. The program itself is also highly scalable and can add or reduce packaging modules according to the actual number of cold boxes to solve a series of problems in the prior art, such as heavy workload for personnel and difficult maintenance.

[0031] In the embodiment of the present application, the present application uses the DCS control system as a platform, uses the ST language to write and encapsulate the core programs such as the switching condenser's hot and cold oil inlet and outlet valves, raw material inlet and outlet valves, etc., and uses the FBD language to build auxiliary programs such as timing and interlocking protection programs. By combining the two, the fully automatic control of the switching condenser is realized, so as to achieve the purposes of improving the reliability of equipment operation, improving product quality, reducing raw material waste, reducing the operator's load and error rate, etc.

[0032] In one embodiment, it also includes an exhaust gas washing tower, a thermal oil heating element, and a thermal oil cooling element. The distributed control system 11 is used to determine whether the switching condenser operating condition is normal based on the working status of the valve 13, the liquid level switch status of the exhaust gas washing tower circulation section, the working status of the thermal oil heating element, and the working status of the thermal oil cooling element.

[0033] In one embodiment, there are four cold boxes, and the valves 13 include a hot gas raw material inlet valve, a hot and cold oil inlet three-way valve, a hot and cold oil outlet three-way valve, an oil cooling bypass valve, an exhaust valve, and an emergency nitrogen fire extinguishing valve.

[0034] In the embodiment of the present application, the present application may include four cold boxes E121A\B\C\D, multiple valves 13UV1212 / 1222 / 1232 / 1242 on the pipelines of the four cold boxes, hot gas raw material inlet valves UV1217 / 1227 / 1237 / 1247 hot and cold oil inlet three-way valves, hot and cold oil outlet three-way valves UV1219 / 1229 / 1239 / 1249, oil cooling bypass valves UV1255 / 1256 / 1257 / 1258, exhaust valves UV1214 / 1224 / 1234 / 1244, and UV1251 / 1252 / 1253. 253 / 1254 emergency nitrogen fire extinguishing valve, tail gas washing tower C-131, crude phthalic anhydride tank V-121, thermal oil cooler E-122 and thermal oil heater E-123 and valve 13 corresponding to the limit switch for detecting whether the switch is in place, multiple temperature measuring points TI1217 / 1227 / 1237 / 1247 on the four cold box pipelines switch condenser thermal oil inlet temperature, TI1214 / 1224 / 1234 / 1244 switch condenser thermal oil outlet temperature, TI1212 / 1222 / 1232 / 1242 switch condenser tail gas outlet temperature. Distributed control system 11 also includes a display module. On the operation screen of the display module, the interface of key process parameters such as the initial number of program steps, hot and cold oil switching time, hot melting time, precooling time, condensation time, initial opening of hot gas raw material valve, hot gas raw material valve interval time, hot gas raw material valve interval opening is open for operators to modify at any time. The operation timetable shows the remaining hot melting time, remaining precooling time, remaining condensation time and the current process stage of each cold box.

[0035] In the embodiment of the present application, the sensor 12 can detect the temperature of the key position of the detection system, the liquid level switch of the tail gas washing tower circulation section, the limit switch of the valve 13 and other signals. The processing module 112 performs logical processing on the real-time process status sent by the sensor 12, and outputs a current signal or a voltage signal to the on-site valve 13 through the control module 111, thereby achieving the control purpose.

[0036] In one possible implementation, it also includes a plurality of manual and automatic buttons and a plurality of interlock reset buttons provided on each cold box.

[0037] In the embodiment of the present application, each cold box has a manual automatic button, which allows the operator to adjust whether the cold box is put into automatic operation at will. Each cold box has an interlock reset button, and the general program has a one-touch start and stop button and a fault reset button. The entire control system can achieve fully automatic operation.

[0038] In the embodiment of the present application, the travel time of all valves 13 is 20 seconds, regardless of the switch. If the system does not receive the corresponding feedback signal within 20 seconds of the output command, it will alarm. The program will automatically switch the cold box to which the faulty valve 13 belongs back to the manual mode, and the remaining cold boxes will operate automatically as usual. For example, the E121A cold box to which the UV1219 valve belongs, during the operation, the UV1219 valve 13 opening command is issued, but no opening feedback signal is received within 20S or the switch feedback exists at the same time, the system will think that the UV1219 valve 13 is faulty, and the E121A cold box will be automatically switched to the manual mode, and the alarm will be issued to prompt the operator to check. At the same time, the three cold boxes E121B / C / D will operate automatically as usual. After the on-site personnel have eliminated the fault, the operator can click the interlock reset button under the E121A cold box on the operation panel to release the interlock, and then click the automatic button to put E121A back under the control of the main program. The present application incorporates the control of the hot gas raw material valve, i.e., the hot gas valve in the figure, into the program automatic control. The operator can set the initial opening, interval opening and interval time of the hot gas valve in advance. The hot gas valve will start from the initial opening according to the above parameters, with the set interval time as the time span and the set interval opening as the opening span, and gradually increase the opening degree of the hot gas valve until it is fully opened, thereby ensuring that the load of the switching condenser is gradually and steadily increased, which can effectively reduce the waste of raw materials in the existing control method.

[0039] In the embodiment of the present application, the process states such as the switching condenser, the temperature on the pipeline, and the feedback of the valve 13 are obtained; if the process state is selected within the normal parameters and reaches the first preset condition, the distributed control system 11 controls multiple valves 13 to enter the automatic control state. The present application can monitor the process parameter states such as the switching condenser temperature, the abnormal interlocking of the switching condenser valve 13, the control of multiple cold boxes of the switching condenser, the control of automatically cutting off the faulty cold box when the switching condenser cold box fails, and the control of one-button start and stop of the switching condenser. The distributed control system 11 can control the switching condenser to start from any cold box. The switching condenser supports setting the initial opening, interval opening, and interval time. The process parameters of the switching condenser are open in real time. Multiple cold boxes of the switching condenser can be set to manual and automatic control at will. The distributed control system 11 automatically cuts the faulty cold box out of the automatic state when a valve 13 is in a faulty working state, without affecting the operation of other cold boxes. The distributed control system 11 puts the hot gas raw material valve of the feed under automatic program control without manual adjustment. The distributed control system 11 can set the initial opening, opening interval and time interval of the hot gas raw material valve in advance to improve the equipment operation stability, increase product output, reduce raw material waste and reduce emission pollution. The distributed control system 11 automatically opens the combustion air cut-off valve according to the set program. The process parameters of the condenser are open in real time and can be modified online. Multiple cold boxes can be set to manual and automatic switching at will to support special situations without stopping. The distributed control system 11 automatically monitors and switches the operating conditions of the condenser, pipeline, and valve 13 according to the set program, and automatically executes the parking protection program according to abnormal conditions.

[0040] In the embodiments of the present application, 1. In the prior art, the switching condenser control is semi-automatic control or pure manual control, and the operator needs to intervene or manually control in the middle, which has high requirements for the operator and there is a risk of misoperation, and the workload is also large. However, the present invention realizes full automation in the production process of the switching condenser. The operator only needs to click the start and stop button, and the production is fully automated in the middle, which greatly reduces the operation risk and personnel load, and saves a lot of manpower; 2. In the prior art, the control of the hot gas raw material valve is manually controlled, which wastes a lot of manpower, and the opening is difficult to control accurately, which easily causes the waste of raw materials, pollutes the atmosphere, etc.; 3. In the prior art, many process parameters are not open in real time, and the adjustment of parameters requires the instrument personnel to change them in the program background, involving the program download when the device is in operation, which is risky; 4. In the prior art, multiple cold boxes of the switching condenser must be started and stopped at the same time. If there is a problem with a cold box in the middle, the production of the entire switching condenser needs to be stopped. The present invention supports automatic identification of valve 13 failures, and supports automatic switching back to manual mode of the cold box to which the faulty valve 13 belongs and alarms the operator to troubleshoot the fault, and the remaining fault-free cold boxes can still operate automatically without interference. This function greatly reduces the shutdown rate of the phthalic anhydride production unit and reduces the unnecessary life degradation of the upstream main reactor catalyst.

[0041] The following will be combined with the attached Figure 2 , 4 , a control method for a phthalic anhydride production switching condenser provided in an embodiment of the present application is introduced in detail.

[0042] See also Figure 2 , 4 , Figure 2 1 is a flow chart of a control method for a phthalic anhydride production switching condenser provided in an embodiment of the present application. Figure 4 This is a schematic diagram of the normal operation of four cold boxes provided in the embodiment of the present application. Figure 2 , 4 As shown, the method comprises the following steps: S1: Distributed control system obtains control logic program; S2: The distributed control system controls multiple cold boxes to execute corresponding working modes in sequence according to the control logic program; multiple sensors collect real-time process status, and the timing component performs timing when the corresponding valve is opened to obtain the timing status. When the preset cold box executes the preset working mode, the distributed control system controls the valve corresponding to the cold box to perform corresponding actions according to the first real-time temperature or the first feedback status or the timing status of the timing component.

[0043] In the embodiment of the present application, the present application may include four cold boxes (E121A\B\C\D), multiple valves on the pipelines of the four cold boxes (UV1212 / 1222 / 1232 / 1242 hot gas raw material inlet valve, UV1217 / 1227 / 1237 / 1247 hot and cold oil inlet three-way valve, UV1219 / 1229 / 1239 / 1249 hot and cold oil outlet three-way valve, UV1255 / 1256 / 1257 / 1258 oil cooling bypass valve, UV1214 / 1224 / 1234 / 1244 exhaust valve, UV1251 / 1252 / 1253 253 / 1254 emergency nitrogen fire extinguishing valve), tail gas washing tower C-131, crude phthalic anhydride tank V-121, thermal oil cooler E-122 and thermal oil heater E-123 and the corresponding limit switches of the valves for detecting whether the switches are in place, and multiple temperature measuring points on the pipelines of the four cold boxes (TI1217 / 1227 / 1237 / 1247 switching condenser thermal oil inlet temperature, TI1214 / 1224 / 1234 / 1244 switching condenser thermal oil outlet temperature, TI1212 / 1222 / 1232 / 1242 switching condenser tail gas outlet temperature).

[0044] In the embodiment of the present application, under normal circumstances, the operator presets various process parameters and starts the program with one button. The program sequence is as follows: S1: System initialization test: 1. Check that the thermal oil condenser E-122 is working properly, and the temperature adjustment system of the cold oil entering the condenser is automatically put into operation (TIC1203, split-range control of the two valves TV1203A and TV1203B); 2. Check that the steam network is normal, check that the thermal oil heater E-123 is working properly, and the temperature adjustment system of the hot oil entering the condenser is automatically put into operation (the valve TV1204 installed on the steam pipeline is controlled by FIC1202 that controls the steam flow and TIC1204 that controls the thermal oil temperature); 3. Confirm that all relevant valves in the system are fault-free; 4. Confirm on-site that there are no mechanical problems or leaks in the cold box ; 5. Check that the liquid level switches LSAL1302 and LSAL1303 in the middle and upper circulation sections of the tail gas washing tower C131 are normal; 6. The internal operator enters the switching condenser sequential control operation screen and inputs the hot melt, precooling and condensation time; 7. The internal operator puts the four cold boxes into automatic mode in the operation screen; 8. The internal operator sets the initial opening, interval time and interval opening parameters of the hot gas raw material valve according to the process conditions; 9. Set the initial number of steps according to the process requirements. The input numbers are: 1, 4, 7, 10, which correspond to the working order of the four cold boxes E121A / B / C / D respectively. For example, input 1 means that E121A will be put into operation first, and B / C / D will be put into operation in sequence 10. Confirm that the external process conditions are normal; S2: The system starts production, and the first cold box starts hot melting: 1. After everything is confirmed to be correct, the operator presses the main program start button, and the system enters the automatic production mode. According to the initial steps entered in step S1, the four cold boxes start to be put into production in sequence. The following example takes the E121A cold box as the first to be put into production. 2. The system enters step 1, the E121A cold box enters the hot melting mode, and the E121B / C / D cold boxes are in the condensing state; 3. STEP=1 The hot melting step timer is reset to zero, the UV1212 hot gas raw material regulating valve is closed, and the UV1255 oil cooling bypass valve is closed; 4. STEP=1 When the hot gas raw material valve is closed, the feedback signal arrives (GSL_1212=ON), open the hot and cold oil inlet three-way valve UV1217 (open for hot oil inlet, closed for cold oil inlet, UV1216 / 26 / 36 / 46 is the cold oil status mark, and UV1216 (17) is actually the same three-way valve) to input hot oil, close the UV1214 tail gas valve, and the hot oil outlet timer in the step starts timing; 5. Wait for the oil temperature TISA_1214 in the cold box to be greater than or equal to 125 degrees or the hot oil outlet timer in the step to complete the timing, open the hot and cold oil outlet three-way valve UV1219 (open for hot oil outlet, closed for cold oil outlet, UV1218 / 28 / 38 / 48 is the cold oil status mark, and UV1218 (19) is actually the same three-way valve), and start hot oil circulation to maintain the hot melt temperature of the cold box. 6. Wait for the external hot melt timer built by FBD to complete timing, and send the hot melt completion signal to the ST packaged step function block; S3: The first cold box is hot melted and precooling starts: 1. The external hot melt timer is completed and the system enters step 2; 2. STEP=2, first clear the hot oil outlet timer in the previous step, maintain the closed state of the UV1212 hot gas raw material regulating valve, maintain the closed state of the UV1214 tail gas valve, maintain the closed state of the UV1255 oil cooling bypass valve, close the UV1217 hot and cold oil inlet three-way valve (UV1216 logo turns green, the three-way valve starts to input cold oil), and the cold oil outlet timer in the step starts to count; 3. STEP=2 waits for the oil temperature TISA_1214 in the cold box to be less than or equal to 125 degrees or the cold oil outlet timer in the step to finish timing, close the UV1219 hot and cold oil outlet three-way valve (UV1218 logo turns green, the three-way valve starts to output cold oil), maintain the cold oil circulation to reduce the precooling temperature of the cold box. 4. Wait for the external precooling timer built by FBD to finish timing, and send the precooling completion signal to the ST packaged step function block; S4: The precooling of the first cold box is completed and condensation begins: 1. The external precooling timer is completed and the system enters step 3; 2. STEP=3, first clear the cold oil outlet timer in the previous step, temporarily maintain the closed state of the UV1212 hot gas raw material regulating valve, open the UV1214 tail gas valve, open the UV1255 oil cooling bypass valve, maintain the closed state of the UV1217 hot and cold oil inlet three-way valve (maintain the cold oil input state), and maintain the closed state of the UV1219 hot and cold oil outlet three-way valve (maintain the cold oil output state); 3. STEP=3 confirms that the UV1214 tail gas valve opening feedback signal has arrived (GSH_1214=ON) and the oil temperature TISA_1214 in the cold box is less than or equal to 70 degrees, the program switches the UV1212 hot gas raw material regulating valve to the automatic state, first opens to the initial opening input by S1, and then gradually increases the interval opening set by S1 according to the interval time set by S1 until it is fully open. 4. STEP=3. After the UV1212 hot gas raw material regulating valve is opened, the high-temperature raw gas from the upstream begins to be input into the first cold box and is cooled to below 131°C in the cold box. The raw gas condenses into needle-shaped solid phthalic anhydride between 131°C and 65°C. The ideal temperature of the non-condensable gas leaving the switching condenser is 65°C and goes to the C-131 tail gas washing tower through the opened tail gas valve. It is discharged into the atmosphere after being washed with chemical solutions and water. 5. The first cold box is completed, and the phthalic anhydride raw gas is in a condensed state afterwards until the first cycle of the program is completed and the first step of hot melt mode is re-entered. The condensed solid phthalic anhydride is melted and flows into the V-121 crude phthalic anhydride tank, and then it is pre-cooled and condensed again to start the second cycle. 6. Wait for the external condensation timer built by FBD to complete the timing, and transmit the condensation step signal to the step function block packaged in ST S5: The second cold box starts hot melting: 1. The external condensation timer is completed, and the system enters step 4; 2. STEP=4, cold box B enters hot melting mode, and cold boxes A / C / D maintain condensing mode; 3. STEP=4, the hot melting step timer in step is reset, the hot gas raw material regulating valve UV1222 is closed, and the oil cooling bypass valve UV1256 is closed; 4. STEP=4, the hot gas raw material valve is closed and the feedback signal arrives (GSL_1222=ON), the hot oil inlet three-way valve UV1227 is opened to input hot oil, the tail gas valve UV1224 is closed, and the hot oil outlet timer in the step starts timing; 5. Wait for the oil temperature TISA_1224 in the cold box to be greater than or equal to 125 degrees or the hot oil outlet timer in the step to complete, open the hot oil outlet three-way valve UV1229 to output hot oil, and start hot oil circulation to maintain the hot melting temperature of the cold box. 6. Wait for the external hot melting timer built by FBD to complete timing, and send the hot melting completion signal to the step function block encapsulated in ST; S6: The second cold box is hot melted and precooling begins: 1. The external hot melt timer is completed and the system enters step 5; 2. STEP=5, first clear the hot oil outlet timer in the previous step, maintain the closed state of the UV1222 hot gas raw material regulating valve, maintain the closed state of the UV1224 tail gas valve, maintain the closed state of the UV1256 oil cooling bypass valve, close the UV1227 hot and cold oil inlet three-way valve to start inputting cold oil, and the cold oil outlet timer in the step starts timing; 3. STEP=5, wait for the oil temperature TISA_1224 in the cold box to be less than or equal to 125 degrees or the cold oil outlet timer in the step to complete, close the UV1229 hot and cold oil outlet three-way valve to start outputting cold oil, and maintain the cold oil circulation to reduce the precooling temperature of the cold box. 4. Wait for the external precooling timer built by FBD to complete timing, and send the precooling completion signal to the ST packaged step function block S7: The second cold box precooling is completed and condensation begins: 1. The external precooling timer is completed and the system enters step 6; 2. STEP=6, first clear the cold oil outlet timer in the previous step, temporarily maintain the closed state of UV1222 hot gas raw material regulating valve, open UV1224 tail gas valve, open UV1256 oil cooling bypass valve, maintain the closed state of UV1227 hot and cold oil inlet three-way valve (maintain the cold oil input state), maintain the closed state of UV1229 hot and cold oil outlet three-way valve (maintain the cold oil output state); 3. STEP=6, confirm that the UV1224 tail gas valve opening feedback signal is received (GSH_1224=ON) and the oil temperature TISA_1224 in the cold box is less than or equal to 70 degrees, the program switches the UV1222 hot gas raw material regulating valve to the automatic state, first open to the initial opening input by S1, and then gradually increase the interval opening set by S1 according to the interval time set by S1 until it is fully open. 4. STEP=6. After the UV1222 hot gas raw material regulating valve is opened, the high-temperature raw gas from the upstream begins to be input into the second cold box and is cooled to below 131°C in the cold box. The raw gas condenses into needle-shaped solid phthalic anhydride between 131°C and 65°C. The ideal temperature of the non-condensable gas leaving the switching condenser is 65°C and goes to the C-131 tail gas washing tower through the opened tail gas valve. It is discharged into the atmosphere after being washed with chemical solutions and water. 5. The second cold box is completed, and the phthalic anhydride raw gas is in a condensed state afterwards until the program re-enters the hot melt mode after the first cycle is completed. The condensed solid phthalic anhydride is melted and flows into the V-121 crude phthalic anhydride tank, and then it is pre-cooled and condensed again to start the second cycle. 6. Wait for the external condensation timer built by FBD to complete the timing, and transmit the condensation step signal to the step function block encapsulated in ST; S8: The third cold box starts hot melting: 1. The external condensation timer is completed, and the system enters step 7; 2. STEP=7, the C cold box enters the hot melting mode, and the A / B / D cold boxes maintain the condensing mode; 3. STEP=7, the hot melting step timer in the step is reset, the UV1232 hot gas raw material regulating valve is closed, and the UV1257 oil cooling bypass valve is closed; 4. STEP=7, the hot gas raw material valve is closed. Feedback signal arrives (GSL_1232=ON), the UV1237 hot and cold oil inlet three-way valve is opened to input hot oil, the UV1234 tail gas valve is closed, and the hot oil outlet timer in the step starts timing; 5. Wait for the oil temperature TISA_1234 in the cold box to be greater than or equal to 125 degrees or the hot oil outlet timer in the step to complete the timing, open the UV1239 hot and cold oil outlet three-way valve to output hot oil, and start hot oil circulation to maintain the hot melting temperature of the cold box. 6. Wait for the external hot melting timer built by FBD to complete the timing, and send the hot melting completion signal to the ST packaged step function block; S9: The third cold box has completed hot melting and started precooling: 7. The external hot melting timer has completed timing, and the system enters step 8; 8. STEP=8, first clear the hot oil outlet timer in the previous step, maintain the closed state of the UV1232 hot gas raw material regulating valve, maintain the closed state of the UV1234 tail gas valve, maintain the closed state of the UV1257 oil cooling bypass valve, close the UV1237 hot and cold oil inlet three-way valve to start inputting cold oil, and the cold oil outlet timer in the step starts timing; 9. STEP=8, wait for the oil temperature TISA_1234 in the cold box to be less than or equal to 125 degrees or the cold oil outlet timer in the step to complete timing, close the UV1239 hot and cold oil outlet three-way valve to start outputting cold oil, and maintain the cold oil circulation to reduce the precooling temperature of the cold box. 10. Wait for the external precooling timer built by FBD to complete timing, and send the precooling completion signal to the ST packaged step function block S10: The third cold box precooling is completed and condensation begins: 1. The external precooling timer is completed and the system enters step 9; 2. STEP=9, first clear the cold oil outlet timer in the previous step, temporarily maintain the closed state of UV1232 hot gas raw material regulating valve, open UV1234 tail gas valve, open UV1257 oil cooling bypass valve, maintain the closed state of UV1237 hot and cold oil inlet three-way valve (maintain the cold oil input state), maintain the closed state of UV1239 hot and cold oil outlet three-way valve (maintain the cold oil output state); 3. STEP=9, confirm that the UV1234 tail gas valve opening feedback signal is received (GSH_1234=ON) and the oil temperature TISA_1234 in the cold box is less than or equal to 70 degrees, the program switches the UV1232 hot gas raw material regulating valve to the automatic state, first open to the initial opening input by S1, and then gradually increase the interval opening set by S1 according to the interval time set by S1 until it is fully open. 4. STEP=9. After the UV1232 hot gas raw material regulating valve is opened, the high-temperature raw gas from the upstream begins to be input into the third cold box and is cooled to below 131°C in the cold box. The raw gas condenses into needle-shaped solid phthalic anhydride between 131°C and 65°C. The ideal temperature of the non-condensable gas leaving the switching condenser is 65°C and goes to the C-131 tail gas washing tower through the opened tail gas valve. It is discharged into the atmosphere after being washed with chemical solutions and water. 5. The third cold box is completed, and the phthalic anhydride raw gas is in a condensed state afterwards until the program re-enters the hot melt mode after the first cycle is completed. The condensed solid phthalic anhydride is melted and flows into the V-121 crude phthalic anhydride tank, and then it is re-precooled and condensed to start the second cycle. 6. Wait for the external condensation timer built by FBD to complete the timing, and transmit the condensation step signal to the step function block packaged in ST; S11: The fourth cold box starts hot melting: 11. The external condensation timer is completed, and the system enters step 10; 12. STEP=10, the D cold box enters the hot melting mode, and the A / B / C cold boxes maintain the condensing mode; 13. STEP=10, the hot melting step timer in the step is reset, the UV1242 hot gas raw material regulating valve is closed, and the UV1258 oil cooling bypass valve is closed; 14. STEP=10, the hot gas raw material valve is closed. The feedback signal arrives (GSL_1242=ON), the UV1247 hot and cold oil inlet three-way valve is opened to input hot oil, the UV1244 tail gas valve is closed, and the hot oil outlet timer in the step starts timing; 15. Wait for the oil temperature TISA_1244 in the cold box to be greater than or equal to 125 degrees or the hot oil outlet timer in the step is completed, open the UV1249 hot and cold oil outlet three-way valve to output hot oil, and start hot oil circulation to maintain the hot melting temperature of the cold box. 16. Wait for the external hot melt timer built by FBD to complete timing and send the hot melt completion signal to the stepping function block of ST package; S12: The fourth cold box hot melt is completed and precooling begins: 17. The external hot melt timer is completed and the system enters step 11; 18. STEP=11, first clear the hot oil outlet timer in the previous step, maintain the closed state of the UV1242 hot gas raw material regulating valve, maintain the closed state of the UV1244 tail gas valve, maintain the closed state of the UV1258 oil cooling bypass valve, close the UV1247 hot and cold oil inlet three-way valve to start inputting cold oil, and the cold oil outlet timer in the step starts timing; 19. STEP=11, wait for the oil temperature TISA_1244 in the cold box to be less than or equal to 125 degrees or the cold oil outlet timer in the step to complete, close the UV1249 hot and cold oil outlet three-way valve to start outputting cold oil, and maintain the cold oil circulation to reduce the precooling temperature of the cold box. 20. Wait for the external precooling timer built by FBD to complete timing, and send the precooling completion signal to the ST packaged stepper function block; S13: The fourth cold box precooling is completed and condensation begins: 7. The external precooling timer is completed and the system enters step 12; 8. STEP=12, first clear the cold oil outlet timer in the previous step, temporarily maintain the closed state of UV1242 hot gas raw material regulating valve, open UV1244 tail gas valve, open UV1258 oil cooling bypass valve, maintain the closed state of UV1247 hot and cold oil inlet three-way valve (maintain the cold oil input state), maintain the closed state of UV1249 hot and cold oil outlet three-way valve (maintain the cold oil output state); 9. STEP=12, confirm that the UV1244 tail gas valve opening feedback signal arrives (GSH_1244=ON) and the oil temperature TISA_1244 in the cold box is less than or equal to 70 degrees, the program switches the UV1242 hot gas raw material regulating valve to the automatic state, first open to the initial opening input by S1, and then gradually increase the interval opening set by S1 according to the interval time set by S1 until it is fully open. 10. STEP=12. After the UV1242 hot gas raw material regulating valve is opened, the high-temperature raw gas from the upstream begins to be input into the fourth cold box and is cooled to below 131°C in the cold box. The raw gas condenses into needle-shaped solid phthalic anhydride between 131°C and 65°C. The ideal temperature of the non-condensable gas leaving the switching condenser is 65°C and goes to the C-131 tail gas washing tower through the opened tail gas valve. It is discharged into the atmosphere after being washed with chemical solutions and water. 11. The fourth cold box is completed, and the phthalic anhydride raw gas is in a condensed state afterwards until the program re-enters the hot melt mode after the first cycle is completed. The condensed solid phthalic anhydride is melted and flows into the V-121 crude phthalic anhydride tank, and then it is re-precooled and condensed to start the second cycle. 12. Wait for the external condensation timer built by FBD to complete the timing, and send the condensation step signal to the ST packaged step function block. S14: The first cold box restarts hot melting: 1. After the external condensation timer finishes timing, the system returns to step 1, and the first cold box starts hot melting again. The melted phthalic anhydride flows into the subsequent V-121 crude phthalic anhydride tank, and the entire system starts to recirculate and continuously produce phthalic anhydride.

[0045] Those skilled in the art can clearly understand that the technical solutions of the embodiments of the present application can be implemented with the help of software and / or hardware. The "unit", "module" and "part" in this specification refer to software and / or hardware that can independently complete or cooperate with other components to complete specific functions, where the hardware can be, for example, a field programmable gate array (FPGA), an integrated circuit (IC), etc.

[0046] Each processing unit and / or module of the embodiments of the present application may be implemented by an analog circuit that implements the functions described in the embodiments of the present application, or may be implemented by software that executes the functions described in the embodiments of the present application.

[0047] See also Figure 3 , which shows a schematic diagram of the structure of an electronic device involved in an embodiment of the present application, the electronic device can be used to implement Figure 1 The method in the embodiment shown. Figure 3 As shown, the electronic device 300 may include: at least one central processor 301 , at least one network interface 304 , a user interface 303 , a memory 305 , and at least one communication bus 302 .

[0048] The communication bus 302 is used to realize the connection and communication between these components.

[0049] The user interface 303 may include a display screen (Display) and a camera (Camera). Optionally, the user interface 303 may also include a standard wired interface and a wireless interface.

[0050] The network interface 304 may optionally include a standard wired interface or a wireless interface (such as a WI-FI interface).

[0051] Among them, the central processing unit 301 may include one or more processing cores. The central processing unit 301 uses various interfaces and lines to connect various parts of the entire electronic device 300, and executes various functions and processes data of the terminal 300 by running or executing instructions, programs, code sets or instruction sets stored in the memory 305, and calling data stored in the memory 305. Optionally, the central processing unit 301 can be implemented in at least one hardware form of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), and programmable logic array (Programmable Logic Array, PLA). The central processing unit 301 can integrate one or a combination of a central processing unit (Central Processing Unit, CPU), a graphics processing unit (Graphics Processing Unit, GPU) and a modem. Among them, the CPU mainly processes the operating system, user interface and application programs; the GPU is responsible for rendering and drawing the content to be displayed on the display screen; and the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the central processing unit 301, but implemented separately through a chip.

[0052] Among them, the memory 305 may include a random access memory (Random Access Memory, RAM) and may also include a read-only memory (Read-Only Memory). Optionally, the memory 305 includes a non-transitory computer-readable storage medium. The memory 305 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 305 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory 305 may optionally be at least one storage device located away from the aforementioned central processor 301. As Figure 3 As shown, the memory 305 as a computer storage medium may include an operating system, a network communication module, a user interface module, and program instructions.

[0053] exist Figure 3 In the electronic device 300 shown, the user interface 303 is mainly used to provide an input interface for the user and obtain the data input by the user; and the central processor 301 can be used to call an application program of a control method for a phthalic anhydride production switching condenser stored in the memory 305, and specifically perform the following operations: S1: Get real-time process status; S2: Controlling multiple cold boxes to perform corresponding cold box operation actions in sequence according to the real-time process status, wherein the cold box operation actions specifically include: hot melting of the cold box; precooling when the hot melting of the cold box is completed; and condensing when the precooling of the cold box is completed.

[0054] The present application also provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, the steps of the above method are implemented. The computer-readable storage medium may include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a micro drive, and a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic card or an optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0055] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0056] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0057] In the several embodiments provided in the present application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are only schematic, such as the division of the units, which is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some service interfaces, and the indirect coupling or communication connection of devices or units can be electrical or other forms.

[0058] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0059] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0060] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a memory, including a number of instructions to enable a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned memory includes: U disk, read-only memory (ROM), random access memory (RAM), mobile hard disk, disk or optical disk and other media that can store program codes.

[0061] A person skilled in the art may understand that all or part of the steps in the various methods of the above embodiments may be completed by entering a program to instruct related hardware. The program may be stored in a computer-readable memory, and the memory may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0062] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A control system for a phthalic anhydride production switch condenser, characterized in that: The invention comprises a distributed control system (11), a timing component, a plurality of sensors (12), a plurality of cold boxes arranged in a switching condenser, a plurality of pipes connected to the plurality of cold boxes, and a plurality of valves (13) arranged on the plurality of pipes, wherein the plurality of sensors (12) are used to collect real-time process status, the timing component is used to perform timing when a preset valve is opened to obtain a timing status, the real-time process status comprising a first real-time temperature of oil in the cold box and a first feedback status of the plurality of valves (13); the distributed control system (11) comprises a control logic program; the distributed control system (11) controls the plurality of cold boxes to execute corresponding working modes in sequence according to the control logic program, and when the preset cold box executes the preset working mode, the distributed control system (11) controls the valve corresponding to the cold box to execute a corresponding action according to the first real-time temperature or the first feedback status or the timing status of the timing component.

2. A control system for a phthalic anhydride production switch condenser as claimed in claim 1, characterized in that: The working modes of the cold box include three working modes: hot melting, precooling, and condensing. The distributed control system (11) controls a cold box to perform the three working modes of hot melting, precooling, and condensing in sequence.

3. A control system for a phthalic anhydride production switch condenser as claimed in claim 2, characterized in that: The multiple valves include a hot gas raw material inlet valve corresponding to each cold box, a hot and cold oil inlet three-way valve corresponding to each cold box, a hot and cold oil outlet three-way valve corresponding to each cold box, an oil cooling bypass valve corresponding to each cold box, an exhaust valve corresponding to each cold box, and an emergency nitrogen fire extinguishing valve corresponding to each cold box.

4. A control system for a phthalic anhydride production switch condenser as claimed in claim 2 or 3, characterized in that: The distributed control system (11) comprises a control module (111), a processing module (112) for performing logic processing on real-time process status, and a programming module capable of inputting a control logic program. The control module (111) is used to output high and low level signals and / or industrial current output signals to corresponding valves (13) according to the control logic program. The control logic program comprises a core program and an auxiliary program. The core program comprises a cold and hot oil inlet and outlet valve control program, a raw material inlet and outlet valve control program, and a multiple cold box switching program. The auxiliary program comprises an interlocking protection program and a timing program. The core program is written in ST language, and the auxiliary program is written in FBD language.

5. A control system for a phthalic anhydride production switch condenser as claimed in claim 3, characterized in that: The timing component comprises a hot oil outlet timer. When a cold box is in a hot melt working mode, the distributed control system (11) controls the hot and cold oil inlet three-way valve corresponding to the cold box to open so as to input hot oil into the cold box and controls the hot oil outlet timer to start timing. The distributed control system (11) controls the hot and cold oil outlet three-way valve corresponding to the cold box to open when the first real-time temperature corresponding to the cold box is not less than the first preset temperature or the timing state of the hot oil outlet timer is at the end.

6. A control system for a phthalic anhydride production switch condenser as claimed in claim 5, characterized in that: The timing component also includes a cold oil outlet timer. When a cold box is in a pre-cooling working mode, the distributed control system (11) controls the cold and hot oil inlet three-way valve corresponding to the cold box to close and controls the cold oil outlet timer to start timing. When the first real-time temperature corresponding to the cold box is not greater than the second preset value or the timing state of the cold oil outlet timer is at the end, the cold and hot oil outlet three-way valve corresponding to the cold box is controlled to close.

7. A control system for a phthalic anhydride production switch condenser as claimed in claim 6, characterized in that: When a cold box is in a condensing working mode, the distributed control system (11) controls the exhaust valve and the oil cooling bypass valve respectively corresponding to the cold box to open; when a first feedback state signal of the exhaust valve is obtained and the first real-time temperature of the cold box is not greater than a third preset value, the distributed control system (11) controls the hot gas raw material regulating valve corresponding to the cold box to switch to a first preset state; and the distributed control system (11) controls the hot gas raw material regulating valve to adjust to a first preset opening at a first preset time interval so as to adjust the hot gas raw material regulating valve from an initial opening to a target opening.

8. A control method for a switch condenser in phthalic anhydride production, characterized in that: The steps include: S1: Distributed control system obtains control logic program; S2: The distributed control system controls multiple cold boxes to execute corresponding working modes in sequence according to the control logic program; multiple sensors collect real-time process status, and the timing component performs timing when the corresponding valve is opened to obtain the timing status. When the preset cold box executes the preset working mode, the distributed control system controls the valve corresponding to the cold box to perform corresponding actions according to the first real-time temperature or the first feedback status or the timing status of the timing component.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to claim 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to claim 8 are implemented.

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