Descaling control method and device for EVA (Ethylene Vinyl Acetate) tubular system, equipment and medium

Abstract

The invention relates to a descaling control method, device, equipment and medium for an EVA tubular system.The descaling control method comprises the steps that S1, the quality index of an EVA product is detected during production, if the quality index of the EVA product is smaller than a preset quality index, the water temperature of a hot water system is controlled to rise to the preset temperature, and if the quality index of the EVA product is smaller than the preset quality index, the water temperature of the hot water system rises to the preset temperature; only the polymerization reaction is stopped and the extrusion system is closed; s2, the reaction pressure is controlled to be first preset pressure, and meanwhile, the VA content in the system is controlled to be a preset value; and S3, the outlet pressure of the primary machine is controlled to be second preset pressure, and circulating cleaning is conducted for preset time. According to the descaling control method provided by the invention, under the condition that the EVA tubular system is locally shut down, the materials in the system are utilized to efficiently remove the wall-adhered materials on the inner wall of the reactor and the inner wall of the product cooler, so that a good descaling effect can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of EVA synthesis, and particularly to a scale removal control method, device, equipment, and medium for an EVA tubular system, and more particularly to a scale removal control method, device, equipment, and medium for a BASF EVA tubular process system. Background Art

[0002] Currently, ethylene vinyl acetate copolymer (EVA) is obtained by introducing vinyl acetate (VA) on the basis of polyethylene, and its VA content is generally 5-40%. Compared with polyethylene, since vinyl acetate monomer is introduced into its molecular chain, the crystallinity is reduced, and the flexibility, impact resistance, filler compatibility, and heat sealing performance are improved. It is widely used in fields such as foamed shoe materials, functional greenhouse films, packaging films, hot melt adhesives, wire and cable, photovoltaic encapsulation, and toys.

[0003] A typical BASF EVA process flow can be divided into four processes: compression, polymerization, extrusion, and pneumatic conveying. After the raw material ethylene and the low-pressure recycle gas compressed by the booster are combined, they enter the first compressor together with the regulator and are compressed to 24 MPa. The gas compressed by the first compressor is combined with the gas from the high recycle, mixed with the comonomer VA, and then enters the second compressor. After being compressed to 200-250 MPa, it enters the tubular reactor after being heated by a preheater. The high-pressure process gas undergoes a highly exothermic high-pressure bulk polymerization reaction under the action of an initiator in the tubular reactor; the polymer at the outlet of the tubular reactor and the mixture of unreacted ethylene, VA, regulator, etc. are cooled by a product cooler and then sent to a high-pressure separator for the first separation. The separated polymer is discharged from its bottom to a low-pressure separator, and the gas enters the high recycle heat exchange system through the top of the high-pressure separator to be cooled and then re-enters the inlet of the second compressor for recycling; after the polymer in the low-pressure separator is separated again, the melt enters the extruder for pelletizing, and after drying, blending, and degassing, it is sent to packaging, while the gas enters the low-pressure recycle system, is recovered and pressurized by the booster, and then sent to the first compressor for recycling.

[0004] However, during the production process of EVA, it is easy to adhere to the walls in the tubular reactor and the aftercooler, resulting in unqualified product quality. The device is forced to stop for maintenance, which will directly shorten the operation time of the device and reduce the production output. Therefore, the wall adhesion of the reactor and the aftercooler has become the main factor restricting the long-term stable operation of the EVA device and is an urgent problem to be solved in the current EVA production. This is because the tubular reactor and the product cooler system are jacketed pipes. Since the polymerization reaction is a strong exothermic reaction and the reaction temperature is 200-240°C, hot water needs to be used for heat exchange, and the hot water temperature is about 130-140°C. Since EVA is a high molecular weight polymer, it is extremely easy to form wall-adhering materials in the tubular reactor and the product cooler during the heat exchange process. Larger molecular weight polymers are generated under high temperature and high pressure. After falling off, it is easy to cause an increase in the product crystal points (fish eyes), resulting in unqualified product quality.

[0005] In order to ensure the qualified product quality of the current high-pressure EVA device, especially when producing photovoltaic products, the device needs to be shut down and maintained every three months, resulting in increased operating costs, reduced operating time, and reduced output of the device, which is not conducive to the efficient production of EVA. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a scale removal control method, device, equipment, and medium for an EVA tubular system to solve the defects of low scale removal efficiency, long downtime, and serious raw material loss in the current EVA synthesis device.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a scale removal control method for an EVA tubular system, and the scale removal control method includes:

[0009] S1. During production, detect the quality index of the EVA product. If the quality index of the EVA product < the preset quality index, control the water temperature of the hot water system to rise to the preset temperature, and only stop the polymerization reaction and close the extrusion system;

[0010] S2. Control the reaction pressure to the first preset pressure, and at the same time control the VA content in the system to the preset value;

[0011] S3. Control the outlet pressure of the primary machine to the second preset pressure and circulate for cleaning for the preset time.

[0012] The scale removal control method provided by the present invention can efficiently remove the wall-adhering materials on the inner walls of the reactor and the product cooler by using the materials in the system under the condition of partial shutdown of the EVA tubular system, and can achieve good scale removal effect.

[0013] As a preferred technical solution of the present invention, raising the water temperature of the hot water system to a preset temperature includes: shutting down all the air-cooling equipment of the hot water system and turning on the heating steam for heating;

[0014] The preset temperature is 150 - 160 °C.

[0015] As a preferred technical solution of the present invention, stopping the polymerization reaction includes: stopping the EVA polymerization reaction, stopping the injection of the initiator, stopping the injection of VA, and maintaining the operation of the primary machine and the secondary machine;

[0016] Closing the extrusion system includes: closing the extruder system and disconnecting the pelletizer head.

[0017] As a preferred technical solution of the present invention, controlling the reaction pressure to a first preset pressure includes: controlling the reaction pressure controller to control the reaction pressure to the first preset pressure;

[0018] The first preset pressure is 165 - 175 MPa.

[0019] As a preferred technical solution of the present invention, controlling the VA content in the system to a preset value includes: starting the VA injection device to inject VA into the system to the preset content, and at the same time adjusting the product valve to the preset circulation flow rate;

[0020] The preset content is 30 - 35% by volume percentage;

[0021] The preset circulation flow rate is 62 - 75% of the production flow rate.

[0022] As a preferred technical solution of the present invention, the second preset pressure is 20 - 26 MPa;

[0023] The preset time is ≥2 h.

[0024] As a preferred technical solution of the present invention, after reaching the preset time, determine the volume concentration of VA in the system according to the grade of the product required for re-production, then re-inject the initiator to initiate the polymerization reaction, and at the same time the extrusion system restarts the extrusion pelletizing system for re-production.

[0025] In a second aspect, the present invention provides a scale removal control device for an EVA tubular system, and the scale removal control device includes:

[0026] A temperature control - shutdown module, used to detect the quality index of the EVA product during production. If the quality index of the EVA product < the preset quality index, then control the water temperature of the hot water system to rise to the preset temperature, and only stop the polymerization reaction and close the extrusion system;

[0027] The pressure control-VA input module is used to control the reaction pressure to a first preset pressure and control the VA content in the system to a preset value at the same time;

[0028] The pressure control-cleaning module is used to control the outlet pressure of the primary machine to a second preset pressure and perform cyclic cleaning for a preset time.

[0029] In a third aspect, the present invention provides an electronic device, and the electronic device includes:

[0030] At least one processor; and a memory communicatively connected to the at least one processor;

[0031] Wherein, the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the descaling control method described in the first aspect.

[0032] In a fourth aspect, the present invention provides a computer storage medium, and the computer storage medium stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the descaling control method described in the first aspect is implemented.

[0033] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0034] (1) Each maintenance takes 3-5 days; for the descaling control method provided by the present invention, each time only the polymerization reaction needs to be stopped for 6-10 hours, and it is expected to be 6-8 times a year, and finally the high-pressure EVA device can be maintained once a year; while in the original technology, when the product quality qualification rate decreases, the high-pressure EVA device needs to be shut down for overall maintenance, each maintenance takes 3-5 days, and the cycle is frequent, and it is expected to be maintained once every 3 months. At the same time, the original technology is expected to be maintained 4 times a year, and each maintenance requires the system to be replaced and emptied, and it is expected to lose about 35t of raw materials each time, with a total loss of about 140t. Through the application of the descaling control method of the present invention, the high-pressure EVA device is expected to be maintained once a year, with a loss of about 35t of raw materials. It can be seen that the descaling control method of the present invention significantly reduces the loss rate of raw materials in the descaling operation, and at the same time avoids the impact of overall shutdown on the production of EVA products and the increase in the operating cost of the device.

[0035] (2) When performing thermal cycle descaling in the present invention, only the polymerization reaction needs to be stopped, and the primary machine and the secondary machine still run, reducing the start and stop of large units, increasing the operating time of the device, increasing the product output. For every 1h reduction in maintenance time, 20t of EVA products can be increased. Calculated based on the maximum maintenance time limit of the present invention (descaling for 10h, 8 times a year, 5 days for one maintenance, a total of 200h), compared with the minimum maintenance time limit of the original descaling maintenance (4 times a year, 3 days for one time, a total of 288h), it is reduced by 88h, that is, 1760t of EVA products can be increased, significantly improving the production efficiency. Brief Description of the Drawings

[0036] Figure 1 is a flowchart of a scale removal control method provided by an embodiment of the present invention for a Basel EVA tubular process system;

[0037] Figure 2 is a schematic diagram of a scale removal control device provided by an embodiment of the present invention for a Basel EVA tubular process system;

[0038] Figure 3 is a schematic diagram of an electronic device provided by an embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of the synthesis device used in Embodiment 1 of the present invention.

[0040] In the figure: 10 - electronic device, 11 - processor, 12 - ROM, 13 - RAM, 14 - bus, 15 - I / O interface, 16 - input unit, 17 - output unit, 18 - storage unit, 19 - communication unit;

[0041] 20 - VA buffer tank, 21 - VA injection pump, 22 - primary machine, 23 - secondary machine, 24 - preheater, 25 - tubular reactor, 26 - initiator injection pump, 27 - hot water system, 28 - high - pressure separator, 29 - product valve, 30 - low - pressure separator, 31 - high - circulation heat exchanger, 32 - cooler, 33 - wax collection device, 34 - first separation tank, 35 - low - circulation heat exchanger, 36 - second separation tank, 37 - third separation tank, 38 - waste oil separation tank, 39 - high - pressure leakage gas tank;

[0042] I - vinyl acetate, II - ethylene.

[0043] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the claimed protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed Embodiments

[0044] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non - limiting embodiments of the present invention are as follows:

[0045] This embodiment provides a scale removal control method for an EVA tubular system. As Figure 1 shown, the scale removal control method includes:

[0046] S1. During production, detect the quality index of the EVA product. If the quality index of the EVA product < the preset quality index, then control the water temperature of the hot water system to rise to the preset temperature, and only stop the polymerization reaction and close the extrusion system;

[0047] S2. Control the reaction pressure to a first preset pressure while controlling the VA content in the system to a preset value;

[0048] S3. Control the outlet pressure of the primary machine to a second preset pressure and circulate and clean for a preset time.

[0049] Exemplarily, the EVA tubular system targeted in the present invention includes the following: vinyl acetate feed end, ethylene feed end, primary machine, secondary machine, tubular reactor, hot water system, low-pressure separator, high-pressure separator, etc.

[0050] Among them, the primary machine, secondary machine, and tubular reactor are connected in sequence. The ethylene feed end is connected to the primary machine, the vinyl acetate feed end is connected to the secondary machine, and the hot water system is matched with the tubular reactor for heat removal during the reaction of the tubular reactor. The material obtained after the reaction of the tubular reactor is fed into the high-pressure separator and then fed into the low-pressure separator through the product valve to separate and obtain the EVA product.

[0051] In the present invention, the quality indicators of the EVA product are specifically and reasonably designed according to the product requirements and customer requirements. When the product produced by the EVA synthesis system device does not meet the quality indicators, scale removal is carried out, and the control method of the present invention can be carried out. Exemplarily, the quality indicators of the EVA product can be selected as melt mass flow rate, VA content, color particles, trailing particles, crystal points, etc. Among them, the crystal points can be graded according to the crystal point size to divide the quality indicators, such as the content of crystal points with a particle size of 100 - 300 μm, such as the content of crystal points with a particle size of 300 - 500 μm, such as the content of crystal points with a particle size of 500 - 1000 μm.

[0052] Among them, raising the water temperature of the hot water system to a preset temperature includes: stopping all the air-cooling equipment of the hot water system and opening the heating steam for heating.

[0053] Among them, the preset temperature is 150 - 160 °C. For example, it can be 150 °C, 152 °C, 154 °C, 156 °C, 158 °C or 160 °C, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0054] Among them, stopping the polymerization reaction includes: stopping the EVA polymerization reaction, stopping the injection of the initiator, stopping the injection of VA, and maintaining the operation of the primary machine and the secondary machine.

[0055] Among them, closing the extrusion system includes: closing the extrusion machine system and disconnecting the pelletizer head.

[0056] Among them, controlling the reaction pressure to a first preset pressure includes: controlling the reaction pressure controller to control the reaction pressure to a first preset pressure.

[0057] Among them, the first preset pressure is 165 - 175 MPa. For example, it can be 165 MPa, 166 MPa, 167 MPa, 168 MPa, 169 MPa, 170 MPa, 171 MPa, 172 MPa, 173 MPa, 174 MPa or 175 MPa, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0058] Among them, the VA content in the control system reaching the preset value includes: starting the VA injection device to inject VA into the system until the preset content, and at the same time adjusting the product valve to the preset circulation flow rate.

[0059] Among them, the preset content is 30 - 35% by volume percentage. For example, it can be 30%, 31%, 32%, 33%, 34% or 35%, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0060] Among them, the preset circulation flow rate is 62 - 75% of the production flow rate. For example, it can be 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74% or 75%, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0061] Among them, the second preset pressure is 20 - 26 MPa. For example, it can be 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa or 26 MPa, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0062] Among them, the preset time is ≥2 h. For example, it can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0063] It should be noted that similar to the Basel EVA tubular process that can meet the control process of the present invention can also adopt the control method of the present invention.

[0064] In the present invention, after the thermal cycle descaling is completed, VA is no longer injected, while the VA recovery speed is increased and the VA content in the system is reduced; then, according to the production grade required subsequently, the VA recovery amount is determined, a certain VA concentration in the system is maintained, and VA injection is carried out again to prepare for re - establishing the polymerization reaction. At this time, according to the index and VA content of the required production grade, the initiator is re - injected to initiate the polymerization reaction, the reaction temperature is controlled, and at the same time, the extrusion system restarts the extrusion granulation system and adjusts relevant parameters according to the production grade for re - production.

[0065] Further, the present invention provides a scale removal control device for a Basel EVA tubular process system, as Figure 2 shown. The scale removal control device includes:

[0066] A temperature control - shutdown module, which is used to detect the quality index of the EVA product during production. If the quality index of the EVA product < the preset quality index, it controls the water temperature of the hot water system to rise to the preset temperature, and only stops the polymerization reaction and closes the extrusion system;

[0067] A pressure control - VA input module, which is used to control the reaction pressure to the first preset pressure and at the same time control the VA content in the system to the preset value;

[0068] A pressure control - cleaning module, which is used to control the outlet pressure of the primary machine to the second preset pressure and circulate the cleaning for the preset time.

[0069] In the device provided in this embodiment, a resumption of production module can also be added, which is used to determine the volume concentration of VA in the system according to the grade of the product required for the next production after reaching the preset time, and then re - inject the initiator to initiate the polymerization reaction. At the same time, the extrusion system restarts the extrusion granulation system for the next production.

[0070] Regarding the device in the above - mentioned embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment related to the method, and will not be elaborated here.

[0071] Further, the present invention provides an electronic device. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are only examples and are not intended to limit the implementation of the present invention described herein and / or claimed.

[0072] As Figure 3As shown, the electronic device 10 includes at least one processor 11 and a memory communicatively connected to the at least one processor 11, such as read-only memory (ROM) 12, random access memory (RAM) 13, etc. The memory stores a computer program executable by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, ROM 12, and RAM 13 are connected to each other via a bus 14. The I / O interface 15 is also connected to the bus 14.

[0073] Multiple components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disc, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0074] The processor 11 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the descaling control method for the Basel EVA tubular process system.

[0075] In some embodiments, the descaling control method for the Basel EVA tubular process system can be implemented as a computer program tangibly embodied in a computer-readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the descaling control method for the Basel EVA tubular process system described above can be executed. Alternatively, in other embodiments, the processor 11 can be configured to execute the descaling control method for the Basel EVA tubular process system in any other appropriate manner (e.g., by means of firmware).

[0076] The various embodiments of the systems and techniques described above in this specification can be implemented in digital electronic circuitry, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on a chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which may be a special-purpose or general-purpose programmable processor that receives data and instructions from, and transmits data and instructions to, a storage system, at least one input device, and at least one output device.

[0077] The computer programs for implementing the methods of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the computer programs, when executed by the processor, cause the functions / operations specified in the flowchart and / or block diagram to be implemented. The computer programs can be executed entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0078] In the context of the present invention, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, the computer-readable storage medium can be a machine-readable signal medium. More specific examples of the machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0079] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the electronic device. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, speech input, or tactile input).

[0080] The systems and techniques described herein can be implemented in a computing system including backend components (e.g., as a data server), or a computing system including middleware components (e.g., an application server), or a computing system including frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system including any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected to each other by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), blockchain network, and the Internet.

[0081] A computing system can include a client and a server. The client and the server are generally remote from each other and typically interact through a communication network. The relationship between the client and the server is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or a cloud host, which is a host product in the cloud computing service system and solves the defects of difficult management and weak business scalability existing in traditional physical hosts and VPS services.

[0082] The server provided in this embodiment includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the above-mentioned descaling control method for the Basel EVA tubular process system.

[0083] Unless otherwise specifically stated, terms such as processing, computing, calculating, determining, displaying, etc. can refer to the actions and / or processes of one or more processing or computing systems, or similar devices, which operate on and transform data represented as a physical (such as electronic) quantity in a register or memory of a processing system into other data similarly represented as a physical quantity in a memory, register, or other such information storage, transmission, or display device of the processing system. Information and signals can be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0084] Those skilled in the art should also understand that the various illustrative logical blocks, modules, circuits, and algorithmic steps described in connection with the embodiments of the present invention can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the above description of the various illustrative components, blocks, modules, circuits, and steps has been generally described in terms of their functions. Whether such a function is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Skilled artisans can implement the described functions in a flexible manner for each specific application, but such implementation decisions should not be construed as departing from the scope of the present disclosure.

[0085] The steps of the methods or algorithms described in connection with the embodiments herein can be directly embodied as hardware, software modules executed by a processor, or a combination thereof. The software modules can be located in a RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, register, hard disk, removable disk, CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from and write information to the storage medium. Of course, the storage medium can also be a part of the processor. The processor and the storage medium can be located in an ASIC. The ASIC can be located in a user terminal. Of course, the processor and the storage medium can also exist as discrete components in the user terminal.

[0086] For a software implementation, the techniques described in the present invention can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented inside the processor or outside the processor. In the latter case, it is communicatively coupled to the processor by various means, which are well known in the art.

[0087] Further, in order to clarify the good scale removal effect achieved by the scale removal control method provided by the present invention, the following actual examples are used for illustration, specifically as follows:

[0088] Example 1

[0089] This example specifically targets the device for synthesizing EVA-V2825 products using the Basel EVA synthesis process device for scale removal. The synthesis device used is as Figure 4 shown. After the raw material ethylene II and the low-pressure recycle gas compressed by the booster are combined, they enter the primary machine 22 for compression together with the regulator. The gas compressed by the primary machine is combined with the high-circulation gas and mixed with the comonomer VA transported by the VA injection pump 21 from the VA buffer tank 20, and then enters the secondary machine 23 for compression together. The compressed gas is heated by the preheater 24 and then enters the tubular reactor 25. Under the action of the initiator injected by the initiator injection pump 26, the high-pressure process gas undergoes a strongly exothermic high-pressure bulk polymerization reaction in the tubular reactor 25. During the reaction process, heat is removed from the reaction by the hot water system 27; the polymer at the outlet of the tubular reactor 25 and the mixture of unreacted ethylene, VA, regulator, etc. are sent to the high-pressure separator 28 for the first separation after being cooled by the product cooler. The separated polymer is discharged from its bottom and transported to the low-pressure separator 30 through the product valve 29. The gas enters the high-circulation heat exchanger 31 after being cooled by the cooler 32, and then enters the inlet of the secondary machine 23 for recycling. The wax product obtained after heat exchange is fed into the wax collection device 33; after the polymer in the low-pressure separator 30 is separated again, the melt enters the extruder for pelletizing, and after drying, blending, and degassing, it is sent to packaging. The gas enters the booster for recovery and pressurization through the first separation tank 34, the low-circulation heat exchanger 35, the second separation tank 36, and the third separation tank 37, and then is sent to the primary machine 22 for recycling. During the process, the high-pressure leakage gas generated by the secondary machine 23 is fed into the waste oil separation tank 38 through the high-pressure leakage gas tank 39, and then is fed into the booster through the third separation tank 37. At the same time, the leakage gas generated by the booster is fed into the waste oil separation tank 38, and then is fed into the booster through the third separation tank 37.

[0090] The specific scale removal process is as follows:

[0091] 1. Detect the quality index of the EVA-V2825 product, such as the content of crystal points within the particle size range of 100 - 300 μm. When the content of crystal points within the particle size range of 100 - 300 μm > 80 pieces / 1200 cm 2 , all the air coolers of the hot water system are shut down, and the heating steam is turned on to slowly raise the water temperature of the hot water system to 155 °C; at the same time, the polymerization reaction is stopped. At this time, the initiator injection pump is shut down, the VA injection pump is shut down, and the primary machine and the secondary machine operate normally; the extruder system is shut down, and the head of the pelletizer is disconnected on site to prevent the low-pressure system from being emptied;

[0092] 2. By means of the reaction pressure controller, the reaction pressure is reduced from 200 MPa to 170 MPa to prevent system fluctuations caused by untimely system pressure supplementation and ensure that the scale removal condition is met. At the same time, restart the VA injection pump, inject a large amount of VA into the system, and close the product valve slightly to reduce the recycle flow rate of the low-pressure separator, thereby reducing the precipitation of VA in the system and quickly increasing the VA content in the system to 32% by volume. A total of 20 t of VA is injected. Under the above-mentioned conditions and the high VA content in the system, the large-molecular-weight polymers adhering to the reactor and the product cooler can be softened.

[0093] 3. Control the outlet pressure of the primary machine to 26 MPa to increase the air injection volume of the secondary machine, thereby increasing the process gas flow rate through the reactor and the product cooler, and cooperating with the above-mentioned conditions to cycle for 2 hours to remove the large-molecular-weight polymers adhering to the reactor wall, so as to achieve the purpose of removing the wall sticking material.

[0094] Further, after the thermal cycle scale removal is completed, stop the VA injection pump and stop injecting VA. At the same time, open the product valve to increase the VA recovery speed and reduce the VA content in the system. Then, determine the VA recovery amount according to the subsequent production grade required, maintain a certain VA concentration in the system, restart the VA injection pump again, and make preparations for re-establishing the polymerization reaction. At this time, according to the index and VA content of the required production grade, re-inject the initiator to initiate the polymerization reaction, control the reaction temperature, and at the same time restart the extrusion granulation system of the extrusion system and adjust the relevant parameters according to the production grade to carry out re-production. When re-producing the same product, the obtained product can still reach the equivalent level.

[0095] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0096] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0097] In addition, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A descaling control method for an EVA tubular system, characterized in that: The descaling control method comprises: S1. During production, the quality index of EVA products is tested. If the quality index of EVA products is less than the preset quality index, the water temperature of the hot water system is controlled to rise to the preset temperature, and only the polymerization reaction is stopped and the extrusion system is closed; S2, controlling the reaction pressure to a first preset pressure, and at the same time controlling the VA content in the system to a preset value; S3. Control the outlet pressure of the primary machine to a second preset pressure, and perform cyclic cleaning to a preset time.

2. The descaling control method according to claim 1, characterized in that: The controlling the water temperature of the hot water system to rise to a preset temperature comprises: shutting down all air cooling equipment of the hot water system and turning on heating steam for heating; The preset temperature is 150-160°C.

3. The descaling control method according to claim 1, characterized in that: The stopping of the polymerization reaction includes: stopping the EVA polymerization reaction, stopping the injection of the initiator, stopping the injection of the VA, and maintaining the operation of the primary machine and the secondary machine; The shutting down of the extrusion system comprises: shutting down the extruder system and disengaging the pelletizer head.

4. The descaling control method according to claim 1, characterized in that: Controlling the reaction pressure to the first preset pressure includes: controlling the reaction pressure controller to control the reaction pressure to the first preset pressure; The first preset pressure is 165-175 MPa.

5. The descaling control method according to claim 1, characterized in that: The controlling the VA content in the system to a preset value comprises: starting a VA injection device to inject VA into the system to a preset content, and adjusting a product valve to a preset circulation flow rate; The preset content is 30-35% by volume; The preset circulation flow rate is 62-75% of the production flow rate.

6. The descaling control method according to claim 1, characterized in that: The second preset pressure is 20-26 MPa; The preset time is ≥2h.

7. The descaling control method according to claim 1, characterized in that: After reaching the preset time, the volume concentration of VA in the system is determined according to the brand of the product to be produced again, and then the initiator is re-injected to initiate the polymerization reaction. At the same time, the extrusion system restarts the extrusion granulation system to carry out production again.

8. A descaling control device for an EVA tubular system, characterized in that: The descaling control device comprises: The temperature control-shutdown module is used to detect the quality index of EVA products during production. If the quality index of EVA products is less than the preset quality index, the water temperature of the hot water system is controlled to rise to the preset temperature, and only the polymerization reaction is stopped and the extrusion system is shut down; A pressure control-VA input module, used to control the reaction pressure to a first preset pressure and simultaneously control the VA content in the system to a preset value; The pressure control-cleaning module is used to control the outlet pressure of the primary machine to a second preset pressure and circulate the cleaning to a preset time.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively coupled to the at least one processor; The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the descaling control method according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that: The computer storage medium stores computer executable instructions, and when the computer executable instructions are executed by a processor, the descaling control method according to any one of claims 1 to 7 is implemented.

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