A temperature stabilizing system for caprolactam preheating and reaction

Abstract

The utility model discloses a kind of temperature stabilizing systems of caprolactam preheating and reaction in the technical field of polymerization heat exchange, including preheater, prepolymerization reactor, final polymerization reactor, flow control valve, circulating pump and heater, the flow direction of heat exchange medium is controlled by flow control valve, the temperature in preheater and final polymerization reactor is controlled by flow control valve, the temperature influence of the flow direction and flow of medium to preheater can be detected by temperature sensor and flow sensor, the heat exchange recovery system, according to the variability of polymerization, no longer with temperature as only reference factor, but with temperature as main standard, simultaneously with the flowing heat of heat exchange medium in pipeline system as secondary reference element, simultaneously by two different factors to determine the flow direction and flow of heating and heat exchange medium, reach the more accurate temperature control of caprolactam's prepolymerization and final polymerization, to more effectively guarantee the quality of caprolactam's polymerization product.

Description

Technical Field

[0001] This utility model relates to the field of heat exchange technology for polymerization reactions, and in particular to a temperature stabilization system for preheating and reacting caprolactam. Background Technology

[0002] In the continuous polymerization process of nylon 6, the caprolactam raw material needs to be preheated to a set temperature before being mixed with other additives and then fed into the prepolymerization tower. This allows the caprolactam raw material to be further heated to 240-260℃ in the prepolymerization tower, thereby causing the reaction.

[0003] The existing caprolactam preheating process is generally completed in a heat exchanger, and then it enters the prepolymerization reactor to start a further heating reaction. Subsequently, it enters the final polymerization reactor to complete the exothermic reaction, and finally the polymerization is completed and the product is discharged to supply subsequent production processes.

[0004] The reaction process of caprolactam requires preheating, resulting in heat consumption; the final stage of the reaction releases heat, resulting in heat loss and wasted energy. Therefore, a pipeline is generally used to circulate heat between the initial and final stages of caprolactam reaction for heat recovery. However, since both the initial preheating stage and the subsequent final polymerization reaction need to be maintained at a specific temperature, temperature control is required. Conventional heat recovery systems cannot calculate heat loss and recovery, making it difficult to control the temperature of the entire caprolactam reaction process. As a result, each reaction step in the subsequent process requires a separate sensor and heater to achieve temperature control. This makes the heat recovery system, although capable of recovering heat, very complex and cumbersome, and difficult to control the temperature.

[0005] Based on this, the present invention designs a temperature stabilization system for caprolactam preheating and reaction to solve the above problems. Utility Model Content

[0006] The purpose of this invention is to provide a temperature stabilization system for the preheating and reaction of caprolactam. This heat exchange and recovery system, based on the temperature variability of the polymerization reaction, no longer uses temperature as the sole reference factor, but rather uses temperature as the primary standard, while simultaneously using the flow heat of the heat exchange medium within the pipeline system as a secondary reference factor. By using these two different factors to determine the flow direction and flow rate of the heating and heat exchange medium, more precise temperature control is achieved for both the prepolymerization and final polymerization reactions of caprolactam, thereby more effectively ensuring the quality of the caprolactam polymerization product.

[0007] This invention is achieved as follows: a temperature stabilization system for caprolactam preheating and reaction, comprising: Preheater, prepolymer reactor, final polymerization reactor, flow control valve, circulating pump and heater; The preheater is a heat exchanger, and a temperature sensor is installed on the material outlet pipe of the preheater; The front end of the prepolymer reactor is connected to the material outlet pipe of the preheater, the rear end of the prepolymer reactor is connected to the final polymerization reactor, and the rear end of the final polymerization reactor is connected to the subsequent process pipeline. A temperature controller is installed inside the final polymerization reactor; The inlet of the temperature controller is connected to the outlet of the heater, and the outlet of the temperature controller is connected to the inlet of the flow control valve. The first outlet of the flow control valve is also connected to the heat exchange medium inlet pipeline of the preheater, and a flow sensor is also installed on the first outlet of the flow control valve. The heat exchange medium outlet of the preheater is connected to the inlet of the circulating pump, and the second outlet of the flow control valve is also connected to the inlet of the circulating pump. The outlet of the circulating pump is connected to the inlet of the heater; The flow control valve, temperature sensor, and flow sensor are all connected to the controller.

[0008] Furthermore, both the preheater and the thermostat are shell-and-tube heat exchangers.

[0009] Furthermore, the controller is a PCL controller.

[0010] Furthermore, the flow control valve is a three-way solenoid valve with one inlet and two outlets.

[0011] Furthermore, the heater is an electric heater.

[0012] The beneficial effects of this utility model are as follows: By adding a three-way flow control valve, combined with a temperature sensor at the back end of the preheater and a flow sensor for heat recovery, this utility model can detect the back end temperature of the preheater and the internal raw material temperature of the preheating reactor from multiple dimensions. At the same time, it can calculate the actual polymerization reaction temperature in the final polymerization reactor and calculate the heat of the entire pipeline to ensure that the reaction temperature is kept within a reasonable range. The flow control valve can also control the outlet temperature of the preheater, thereby adjusting the internal temperature of the prepolymerization reactor. The operation is simple and convenient. It also makes the heat recovery system of caprolactam polymerization no longer a separate temperature control, but a whole heat recovery system. It forms complete data of the entire pipeline system and controls the direction of heat conversion by the flow rate and direction of the heat exchange medium. It can also supplement and regulate the heat, making the overall heat exchange medium have a more flexible adjustment method. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1This is a schematic diagram of the overall pipeline system structure of this utility model.

[0015] The attached diagram lists the components represented by each number as follows: 1-Preheater, 11-Temperature sensor, 2-Prepolymer reactor, 21-Final polymerization reactor, 3-Flow control valve, 31-Flow sensor, 4-Circulation pump, 5-Heater, 51-Temperature controller. Detailed Implementation

[0016] Please see Figure 1 As shown, this utility model provides a temperature stabilization system for preheating and reacting caprolactam. To better understand the above technical solution, the following will describe the above technical solution in detail with reference to the accompanying drawings and specific embodiments.

[0017] In a specific embodiment of the technical solution of this utility model: It includes a preheater 1, a prepolymerization reactor 2, a final polymerization reactor 21, a flow control valve 3, a circulating pump 4, and a heater 5; the preheater 1 and the temperature controller 51 can be shell-and-tube heat exchangers, which can completely isolate the medium and the material, and facilitate heat exchange. This makes it easy to control the heat exchange medium in the isolated pipe, and also facilitates the control of temperature and flow rate, so as to achieve the purpose of controlling the heat flow of the whole system.

[0018] Preheater 1 is a heat exchanger, and a temperature sensor 11 is installed on the material outlet pipe of preheater 1; The front end of the prepolymer reactor 2 is connected to the material outlet pipe of the preheater 1, the rear end of the prepolymer reactor 2 is connected to the final polymerization reactor 21, and the rear end of the final polymerization reactor 21 is connected to the subsequent process pipeline of caprolactam. A temperature controller is installed inside the final polymerization reactor 21; The inlet of the temperature controller is connected to the outlet of the heater 5, and the outlet of the temperature controller is connected to the inlet of the flow control valve 3. The flow control valve 3 is a three-way solenoid valve with one inlet and two outlets, which can control the flow direction of the medium in three different directions. The first outlet of the flow control valve 3 is also connected to the heat exchange medium inlet pipeline of the preheater 1, and a flow sensor 31 is also installed on the first outlet of the flow control valve 3, which can monitor the total amount of medium flowing into the preheater 1 in the thermostat in real time. The heat exchange medium outlet of preheater 1 is connected to the inlet of circulating pump 4, and the second outlet of flow control valve 3 is also connected to the inlet of circulating pump 4, forming that the feed port of circulating pump 4 is connected to the heat exchange medium outlet pipeline of preheater 1 and the second outlet of flow control valve 3 respectively through a tee. The outlet of the circulating pump 4 is connected to the inlet of the heater 5, which is an electric heater; The flow control valve 3, temperature sensor 11 and flow sensor 31 are all connected to the controller of the overall thermal circulation pipeline system. The controller is a PCL controller.

[0019] It should be noted that: Because temperature changes in the polymerization reaction exhibit a significant lag, existing control processes adjust valve openings solely based on the difference between the measured and set values ​​of caprolactam temperature at the preheater outlet. This results in substantial fluctuations during actual production, frequently leading to overshoot or oscillations. Consequently, the preheating and final polymerization temperatures of caprolactam fluctuate significantly, severely impacting the polymerization state and causing product quality abnormalities. This system monitors the heat recovered from the temperature controller 51 using a flow sensor 31 and controls the flow through a flow control valve 3, thereby regulating the flow of the recovered heat energy.

[0020] When in use, the preheater 1 preheats the caprolactam raw material to bring it to the initial temperature of the reaction and tries to keep the temperature stable.

[0021] The preheating temperature inside the preheater 1 is detected by the temperature sensor 11, thereby controlling the required temperature inside the preheater 1. When the temperature sensor 11 detects that the temperature is rising, the preheater 1 can be controlled to reduce the heat acquisition appropriately. When the temperature sensor 11 detects that the temperature inside the preheater 1 is too low or that a cooling trend is forming, the heat exchange and transfer inside the preheater 1 is increased by adjusting the flow control valve 3.

[0022] The amount of heat obtained in the preheater 1 is adjusted and controlled by the flow control valve 3.

[0023] The flow control valve 3 controls the direction and flow rate of the heat medium in the front-end temperature controller 51. When the temperature sensor 11 detects that the temperature in the preheater 1 has dropped, heating is required. At this time, the flow control valve 3 controls more heat exchange medium to flow to the preheater 1. At the same time, the flow sensor 31 detects the flow rate of the medium to determine the specific amount of heat obtained in the preheater 1. The final amount of heat obtained is also controlled by the temperature sensor 11.

[0024] If the temperature sensor 11 detects that the temperature remains stable, the flow direction can be controlled by the flow control valve 3 to keep it stable. That is, the flow control valve 3 controls the flow of the heat exchange medium in the system to keep the flow rate in both directions of the preheater 1 and the circulating pump 4 fixed.

[0025] When the temperature sensor 11 detects a temperature drop and the preheater 1 needs to be heated, the flow control valve 3 controls more heat medium to flow to the preheater 1, and the flow sensor 31 controls the flow rate to form a specific value, which facilitates the adjustment of the direction and opening width of the flow control valve 3.

[0026] Similarly, when the temperature sensor 11 detects that the temperature of the preheated caprolactam raw material is too high, the flow control valve 3 controls the flow rate of the superheater 1 to decrease, and the value detected by the flow sensor 31 will also decrease accordingly, with a relative cooling flow range.

[0027] Through experiments, the changes in temperature sensor 11 under different flow rates detected by different flow sensors 31 can be obtained, as well as the corresponding subsequent effects, forming a reasonable adjustment range. Thus, the temperature of temperature sensor 11 can be controlled by flow control valve 3, thereby stabilizing the temperature in prepolymer reactor 2 and final polymerization reactor 21.

[0028] If the flow control valve 3 is closed, the heat exchange between the prepolymer reactor 2 and the final polymerization reactor 21 can be kept still, making the adjustment more flexible.

[0029] When the temperature inside the final polymerization reactor 21 is insufficient, the medium can be heated by the heating coil 5, and the internal reaction of the final polymerization reactor 21 can be heated by the temperature controller 51. Therefore, through the cooperation of the temperature controller 51 and the heating coil 5, the internal reaction of the final polymerization reactor 21 can be stably adjusted by raising and lowering.

[0030] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A temperature stabilization system for preheating and reacting caprolactam, characterized in that, include: Preheater (1), prepolymer reactor (2), final polymerization reactor (21), flow control valve (3), circulation pump (4) and heater (5); The preheater (1) is a heat exchanger, and a temperature sensor (11) is installed on the material outlet pipe of the preheater (1). The front end of the prepolymer reactor (2) is connected to the material outlet pipe of the preheater (1), the rear end of the prepolymer reactor (2) is connected to the final polymerization reactor (21), and the rear end of the final polymerization reactor (21) is connected to the subsequent process pipeline. A temperature controller is installed inside the final polymerization reactor (21); The inlet of the heat exchange medium of the temperature controller is connected to the outlet of the heater (5), and the outlet of the heat exchange medium of the temperature controller is connected to the inlet of the flow control valve (3). The first outlet of the flow control valve (3) is also connected to the heat exchange medium inlet pipeline of the preheater (1), and a flow sensor (31) is also provided on the first outlet of the flow control valve (3). The heat exchange medium outlet of the preheater (1) is connected to the inlet of the circulating pump (4), and the second outlet of the flow control valve (3) is also connected to the inlet of the circulating pump (4). The outlet of the circulating pump (4) is connected to the inlet of the heater (5); The flow control valve (3), temperature sensor (11) and flow sensor (31) are all connected to the controller.

2. The temperature stabilization system for caprolactam preheating and reaction according to claim 1, characterized in that: Both the preheater (1) and the thermostat (51) are shell-and-tube heat exchangers.

3. The temperature stabilization system for caprolactam preheating and reaction according to claim 1, characterized in that: The controller is a PCL controller.

4. The temperature stabilization system for caprolactam preheating and reaction according to claim 1, characterized in that: The flow control valve (3) is a three-way solenoid valve with one inlet and two outlets.

5. The temperature stabilization system for caprolactam preheating and reaction according to claim 1, characterized in that: The heater (5) is an electric heater.

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