Recovery system of dichloroethane in thiophanate-methyl production

Abstract

The application provides a recovery system of dichloroethane in thiophthalimide production, comprising a distillation kettle, a heat exchanger, a storage tank and a negative pressure pump; the top of the distillation kettle is provided with a feeding port and a gas phase outlet, the gas phase outlet is communicated with the storage tank through the heat exchanger, and the top of the storage tank is connected with the negative pressure pump; and the bottom of the distillation kettle is provided with a liquid discharge port. The application realizes efficient recovery of dichloroethane and reduces energy consumption.

Description

Technical Field

[0001] This application relates to the field of pesticide chemical equipment technology, and in particular to a dichloroethane recovery system in the production of thiophanate-methyl. Background Technology

[0002] Thiophanate-methyl, marketed as methyl thiophanate, is a broad-spectrum, systemic, low-toxicity fungicide with systemic, preventative, and curative effects. Currently, dichloroethane is used as a solvent in the production of thiophanate-methyl. After use, the dichloroethane is recovered through distillation and then reused in the next batch of production, reducing waste.

[0003] In existing technologies, dichloroethane is recovered by atmospheric distillation. However, dichloroethane and water can form a binary azeotrope under atmospheric pressure. Therefore, when distilling to recover the solvent dichloroethane, a large amount of water will be distilled out along with it, which not only increases energy consumption, but also increases the temperature and is prone to side reactions. In addition, the large amount of water azeotrope distilled out wastes steam. Utility Model Content

[0004] This application provides a dichloroethane recovery system for the production of methyl thiophanate, in order to solve the problems mentioned in the background art.

[0005] This application provides a system for recovering dichloroethane in the production of methyl thiophanate, comprising: a distillation kettle, a heat exchanger, a storage tank, and a negative pressure pump; The top of the distillation vessel is equipped with a feed inlet and a gas phase outlet. The gas phase outlet is connected to the storage tank via a heat exchanger. The top of the storage tank is connected to a negative pressure pump. The bottom of the distillation vessel is equipped with a drain port.

[0006] Optionally, the storage tank is also connected to a separation tank, with the light phase outlet of the separation tank connected to a water storage tank and the heavy phase outlet of the separation tank connected to a dichloroethane collection tank.

[0007] Optionally, the separation box is equipped with a stirring unit, including a motor, connecting rod, stirring tube, first bevel gear, and second bevel gear; The motor is located on the top of the outside of the separation box. The first bevel gear is connected to the output end of the motor through a connecting rod. The first bevel gear and the second bevel gear are vertically meshed. The second bevel gear is sleeved on the outside of the stirring tube. The stirring tube extends vertically into the inside of the separation box. A stirring paddle is provided on the outside of the stirring tube. The stirring tube is a hollow tube, and the top of the stirring tube is connected to the demulsifier storage tank through a pipeline.

[0008] Optionally, the stirring tube includes an upper straight tube, a middle telescopic tube, and a lower straight tube connected in sequence; The stirring tube is located inside the separation chamber and is symmetrically equipped with telescopic cylinders on both sides. The fixed end of the telescopic cylinder is connected to the upper straight pipe through the first fixing plate, and the telescopic end of the telescopic cylinder is connected to the lower straight pipe through the second fixing plate.

[0009] Optionally, a conduit is horizontally connected to the bottom of the lower straight pipe, and multiple nozzles are connected to the conduit.

[0010] Optionally, the side wall of the separation box is provided with a transparent viewing window.

[0011] Optionally, the water storage tank is connected to the heat exchange medium inlet of the heat exchanger via a water supply pipeline, and the heat exchange medium outlet of the heat exchanger is connected to the water storage tank via a return water pipeline.

[0012] The dichloroethane recovery system provided in this application for the production of methyl thiophanate achieves highly efficient recovery of dichloroethane and has the following advantages compared to existing technologies: (1) This application provides a vacuum environment for the distillation vessel by using a negative pressure pump, thereby reducing the pressure inside the distillation vessel and widening the boiling point difference between dichloroethane and water. This greatly reduces the formation of dichloroethane-water azeotrope, thereby reducing the water content in dichloroethane and improving the quality of dichloroethane. At the same time, it helps to lower the distillation temperature of dichloroethane, greatly reducing energy consumption, and avoiding the decomposition of methyl thiophanate caused by excessively high temperature.

[0013] (2) In the stirring unit of this application, the stirring tube includes an upper straight tube, a middle telescopic tube, and a lower straight tube connected in sequence. The fixed end of the telescopic cylinder is connected to the upper straight tube through a first fixed plate, and the telescopic end of the telescopic cylinder is connected to the lower straight tube through a second fixed plate. When demulsification is required, the telescopic cylinder is opened, the telescopic end of the telescopic cylinder extends, and drives the lower straight tube to move downward, while simultaneously driving the middle telescopic tube to extend. Then the motor is turned on, causing the stirring tube to rotate. At the same time, the demulsifier in the demulsifier storage tank is transported to the separation box through the stirring tube. After the demulsifier is input, the telescopic cylinder is operated to retract. This setting is conducive to the stratification of dichloroethane and water, avoids the influence of the stirring tube on the interface between dichloroethane and water, helps to maintain the clear stratification of the interface, and thus improves the separation efficiency of dichloroethane and water.

[0014] (3) By setting a limiting unit on the stirring tube, including a fixing block, a positioning rod and a limiting block, the fixing block is fixedly set on the upper straight tube and the lower straight tube respectively. The bottom of the positioning rod is fixedly connected to the fixing block located on the lower straight tube. The positioning rod passes through the upper fixing block and the limiting block is fixedly set on the top of the positioning rod. The upper fixing block and the lower fixing block are vertically aligned. This ensures that the stirring tube will not swing in the left and right directions when it moves up and down, which is conducive to the stable operation of the device. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a dichloroethane recovery system in the production of methyl thiophanate provided in an embodiment of this application; Figure 2 A schematic diagram of the structure of a dichloroethane recovery system in the production of methyl thiophanate provided in another embodiment of this application; Figure 3 This is a schematic diagram of the structure of a stirring unit provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a stirring unit provided in another embodiment of this application; Figure 5 This is a connection diagram of a telescopic cylinder provided in one embodiment of this application; Figure 6 This is a schematic diagram of the structure of a limiting unit provided in an embodiment of this application; Figure 7 This is a schematic diagram of the structure of a dichloroethane recovery system in the production of methyl thiophanate, provided in another embodiment of this application.

[0017] Explanation of reference numerals in the attached figures: 1: Distillation kettle, 2: Heat exchanger, 3: Storage tank, 4: Negative pressure pump, 5: Separation box, 6: Demulsifier storage tank, 110: Feed inlet, 120: Gas phase outlet, 130: Drain outlet, 501: Water storage tank, 502: Dichloroethane collection tank, 503: Fixing block, 504: Positioning rod, 505: Limiting block, 510: Motor, 520: Connecting rod, 530: Stirring tube, 531: Upper straight pipe, 532: Middle telescopic pipe, 533: Lower straight pipe, 540: First bevel gear, 550: Second bevel gear, 560: Telescopic cylinder, 561: First fixing plate, 562: Second fixing plate, 570: Conduit, 571: Nozzle, 580: Transparent window, 710: Water supply pipeline, 720: Return water pipeline, 5301: Stirring paddle. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0019] like Figure 1 As shown, this application provides a dichloroethane recovery system in the production of methyl thiophanate, comprising: a distillation kettle 1, a heat exchanger 2, a storage tank 3, and a negative pressure pump 4; The top of the distillation vessel 1 is provided with a feed inlet 110 and a gas phase outlet 120. The gas phase outlet 120 is connected to the storage tank 3 through a heat exchanger 2. The top of the storage tank 3 is connected to a negative pressure pump 4. The bottom of the distillation vessel 1 is provided with a drain port 130.

[0020] Specifically, in the production of methyl thiophanate, dichloroethane is used as a solvent. After the reaction is completed, a mother liquor containing dichloroethane, water and methyl thiophanate is produced. The dichloroethane in the mother liquor is recovered and used for the production of the next batch of methyl thiophanate.

[0021] In the dichloroethane recovery process, the mother liquor is transported to distillation vessel 1 for distillation. Distillation vessel 1 is equipped with a jacket, through which steam is introduced to heat the inside of distillation vessel 1. At the same time, a vacuum environment is provided for distillation vessel 1 by a negative pressure pump 4, which reduces the pressure inside distillation vessel 1. By reducing the pressure, the relative volatility of dichloroethane and water is changed, increasing the difference in their boiling points and reducing the formation of dichloroethane-water azeotropes. This reduces the water content in dichloroethane and improves its quality. At the same time, reducing the pressure of distillation vessel 1 by the negative pressure pump 4 helps to lower the distillation temperature of dichloroethane, greatly reducing the energy consumption of steam and avoiding the decomposition of methyl thiophanate caused by excessively high temperatures. During distillation, the resulting gaseous dichloroethane and a small amount of water vapor are transported from the gas phase outlet 120 to heat exchanger 2 for condensation, yielding liquid dichloroethane and a small amount of water, which are then stored in storage tank 3 for use in the synthesis of the next batch of methyl thiophanate. After distillation, the heavy phase in distillation vessel 1 is discharged through drain port 130 for the purification of methyl thiophanate. The condensate in heat exchanger 2 uses circulating water.

[0022] This application achieves efficient recovery of dichloroethane through the aforementioned device. By providing a vacuum environment to the distillation vessel through a negative pressure pump, the pressure inside the distillation vessel is reduced, thereby widening the boiling point difference between dichloroethane and water. This significantly reduces the formation of dichloroethane-water azeotropes, thereby reducing the water content in dichloroethane and improving its quality. At the same time, it helps to lower the distillation temperature of dichloroethane, greatly reducing energy consumption, and avoiding the decomposition of methyl thiophanate caused by excessively high temperatures.

[0023] like Figure 2 As shown, optionally, the storage tank 3 is also connected to a separation tank 5. The light phase outlet of the separation tank 5 is connected to the water storage tank 501, and the heavy phase outlet of the separation tank 5 is connected to the dichloroethane collection tank 502.

[0024] Specifically, the separation tank 5 is used to allow dichloroethane and a small amount of water from the storage tank 3 to settle and separate into upper water and lower dichloroethane. A light phase outlet valve is installed at the light phase outlet, and a heavy phase outlet valve is installed at the heavy phase outlet. After the separation is completed, the heavy phase outlet valve is opened first to transport the heavy phase dichloroethane to the dichloroethane collection tank 502. Then, the water phase is transported to the water storage tank 501 by opening the light phase outlet valve, thereby achieving the separation of dichloroethane and water, further reducing the water content in dichloroethane and improving the purity of dichloroethane.

[0025] like Figure 3 As shown, optionally, the separation box 5 is equipped with a stirring unit, including a motor 510, a connecting rod 520, a stirring tube 530, a first bevel gear 540, and a second bevel gear 550; The motor 510 is located on the top of the outside of the separation box 5. The first bevel gear 540 is connected to the output end of the motor 510 through the connecting rod 520. The first bevel gear 540 is vertically meshed with the second bevel gear 550. The second bevel gear 550 is sleeved on the outside of the stirring tube 530. The stirring tube 530 extends vertically into the inside of the separation box 5. A stirring paddle 5301 is provided on the outside of the stirring tube 530. The stirring tube 530 is a hollow tube, and the top of the stirring tube 530 is connected to the demulsifier storage tank 6 through a pipeline.

[0026] Specifically, the separation tank 5 is equipped with a stirring unit. The demulsifier in the demulsifier storage tank 6 is transported to the separation tank 5 through the stirring pipe 530. After the demulsifier and the mixture of dichloroethane and a small amount of water in the separation tank 5 are stirred by the stirring unit, they are allowed to stand and separate into layers. This facilitates the thorough mixing of the mixture of dichloroethane and a small amount of water and the demulsifier, changes the charge balance of the azeotropic system of dichloroethane and a small amount of water, makes it easier to separate the components in the emulsion layer, and thus helps dichloroethane and a small amount of water to quickly separate into layers, achieving rapid separation of dichloroethane and water.

[0027] The stirring unit includes a motor 510, a connecting rod 520, a stirring tube 530, a first bevel gear 540, and a second bevel gear 550. When demulsification is required, the demulsifier in the demulsifier storage tank 6 is transported to the separation tank 5 through the stirring tube 530. At the same time, the motor 510 is started, which drives the connecting rod 520 to rotate. The connecting rod 520 drives the first bevel gear 540 to rotate. The first bevel gear 540 drives the second bevel gear 550, which is perpendicularly meshed with it, thereby driving the stirring tube 530 to rotate. The stirring tube 530 drives the stirring paddle 5301 to rotate, mixing the demulsifier, dichloroethane, and a small amount of water, thereby improving the dispersion rate of the demulsifier and thus improving the stratification efficiency of dichloroethane and water.

[0028] Furthermore, the demulsifier is selected from sodium chloride aqueous solution, and the concentration of sodium chloride aqueous solution depends on the actual working conditions and is not limited here.

[0029] like Figure 4 , Figure 5 As shown, optionally, the stirring tube 530 includes an upper straight tube 531, a middle telescopic tube 532 and a lower straight tube 533 connected in sequence. The stirring tube 530 is located inside the separation box 5, and telescopic cylinders 560 are symmetrically arranged on both sides. The fixed end of the telescopic cylinder 560 is connected to the upper straight tube 531 through the first fixing plate 561, and the telescopic end of the telescopic cylinder 560 is connected to the lower straight tube 533 through the second fixing plate 562.

[0030] Specifically, the stirring tube 530 includes an upper straight tube 531, a middle telescopic tube 532, and a lower straight tube 533 connected in sequence. The fixed end of the telescopic cylinder 560 is connected to the upper straight tube 531 through a first fixing plate 561, and the telescopic end of the telescopic cylinder 560 is connected to the lower straight tube 533 through a second fixing plate 562. When demulsification is required, the telescopic cylinder 560 is activated, the telescopic end of the telescopic cylinder 560 extends, and drives the lower straight tube 533 to move downward, while simultaneously driving the middle telescopic tube 532 to extend. Then, the motor 510 is turned on, causing the stirring tube 530 to rotate. At the same time, the demulsifier in the demulsifier storage tank 6 is transported to the separation tank 5 through the stirring tube 530. After the demulsifier is input, the telescopic cylinder 560 is operated to retract, so that the lower straight tube 533 is above the interface between dichloroethane and water. Furthermore, the telescopic cylinder 560 is retracted, so that the lower straight tube 533 is above the liquid level in the separation tank 5. This setup facilitates the separation of dichloroethane and water, avoids the influence of the stirring tube 530 on the interface between dichloroethane and water, helps maintain a clear separation interface, and thus improves the separation efficiency of dichloroethane and water.

[0031] like Figure 6As shown, the stirring tube 530 is further provided with a limiting unit, including a fixing block 503, a positioning rod 504, and a limiting block 505. The fixing blocks 503 are respectively fixedly installed on the upper straight tube 531 and the lower straight tube 533. The bottom of the positioning rod 504 is fixedly connected to the fixing block 503 located on the lower straight tube 533. The top of the positioning rod 504 passes through the upper fixing block 503 and is slidably connected to it. The limiting block 505 is fixedly installed on the top of the positioning rod 504. The upper fixing block 503 and the lower fixing block 503 are vertically aligned. This ensures that the stirring tube 530 will not swing in the left or right direction when it moves up and down, which is beneficial to the stable operation of the device.

[0032] The limiting unit and the telescopic cylinder 560 are staggered on the outer periphery of the stirring tube 530, and there is no contact between them.

[0033] like Figure 4 As shown, optionally, a conduit 570 is horizontally connected to the bottom of the lower straight pipe 533, and multiple nozzles 571 are connected to the conduit 570.

[0034] Specifically, the demulsifier from the stirring tube 530 is sprayed through the conduit 570 and multiple nozzles 571, which improves the mixing efficiency of the demulsifier and dichloroethane. At the same time, it works in conjunction with the stirring device to rapidly demulsify the dichloroethane-water emulsion layer in the separation tank 5, further improving the separation efficiency of dichloroethane and water, thereby reducing the water content in dichloroethane.

[0035] like Figure 7 As shown, optionally, the side wall of the separation box 5 is provided with a transparent viewing window 580.

[0036] Specifically, the transparent window 580 allows operators to easily observe the location of the separation interface between dichloroethane and water in the separation chamber 5, which is beneficial for the separation of dichloroethane and water.

[0037] like Figure 7 As shown, optionally, the water storage tank 501 is connected to the heat exchange medium inlet of the heat exchanger 2 through the water supply pipeline 710, and the heat exchange medium outlet of the heat exchanger 2 is connected to the water storage tank 501 through the return water pipeline 720.

[0038] Specifically, the water obtained from the water storage tank 501 is used as condensate for condensing gaseous dichloroethane, reducing the use of circulating water as condensate. At the same time, the water in the water storage tank 501 is recycled, reducing resource consumption and lowering production costs.

[0039] Furthermore, a temperature sensor is installed in the water storage tank 501. When the temperature sensor reaches the first preset temperature value, the water in the water storage tank 501 is used as condensate. When the temperature sensor reaches the second preset temperature value, the water supply pipe 710 is closed, and circulating water is switched to be used as condensate. In this way, the circulating water and the water in the water storage tank 501 are used alternately, reducing the amount of circulating water used. The first preset temperature value is lower than the second preset temperature value.

[0040] The technical solution of this application will be illustrated in detail below with specific embodiments.

[0041] In this embodiment, the operation flow of the dichloroethane recovery system in the production of methyl thiophanate is as follows: In the dichloroethane recovery process, the mother liquor is fed into distillation vessel 1 for distillation. Distillation vessel 1 is equipped with a jacket, through which steam is circulated to heat the interior. Simultaneously, a vacuum environment is provided to distillation vessel 1 via a negative pressure pump 4, reducing the pressure inside and altering the relative volatility of dichloroethane and water. This widens the boiling point difference between the two, reducing the formation of dichloroethane-water azeotropes and thus lowering the water content in dichloroethane, thereby improving its quality. During distillation, the resulting gaseous dichloroethane and a small amount of steam are transported from the gas outlet 120 to heat exchanger 2 for condensation, yielding liquid dichloroethane and a small amount of water, which are then stored in storage tank 3.

[0042] Initially, circulating water is used as the condensate during distillation. As distillation progresses, when the temperature sensor reaches the first preset temperature value, the water in the storage tank 501 is used as the condensate. When the temperature sensor reaches the second preset temperature value, the water supply line 710 is shut off, and circulating water is switched to be used as the condensate. This alternating use of circulating water and water in the storage tank 501 reduces the amount of circulating water used. The first preset temperature value is lower than the second preset temperature value.

[0043] Dichloroethane and a small amount of water from storage tank 3 are transferred to separation tank 5 for stratification. A small emulsion layer will form between the dichloroethane and water. When demulsification is required, telescopic cylinder 560 is activated. The telescopic end of cylinder 560 extends, driving the lower straight pipe 533 downwards and simultaneously extending the middle telescopic pipe 532. This allows the demulsifier from demulsifier storage tank 6 to be sprayed through stirring pipe 530, conduit 570, and multiple nozzles 571 into separation tank 5. Simultaneously, motor 510 is activated, causing stirring pipe 530 to rotate, ensuring thorough mixing of the demulsifier with dichloroethane and water. After the demulsifier input is complete, telescopic cylinder 560 is retracted, positioning the lower straight pipe 533 above the liquid level in separation tank 5.

[0044] Dichloroethane and a small amount of water and sodium chloride aqueous solution demulsifier are allowed to stand and separate in separation tank 5 to obtain upper water (sodium chloride aqueous solution) and lower dichloroethane. At the same time, a light phase outlet valve is set at the light phase outlet and a heavy phase outlet valve is set at the heavy phase outlet. After the separation is completed, the heavy phase outlet valve is opened first to transport the heavy phase dichloroethane to the dichloroethane collection tank 502 for the synthesis of the next batch of methyl thiophanate. Then, the aqueous phase is transported to the water storage tank 501 by opening the light phase outlet valve.

[0045] The operational plan proposed in this application can reduce steam consumption by 0.8t / t of thiophanate-methyl product, saving 800t of steam consumption and 160,000 yuan in costs annually.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A system for recovering dichloroethane in the production of methyl thiophanate, characterized in that, include: Distillation vessel (1), heat exchanger (2), storage tank (3) and negative pressure pump (4); The top of the distillation vessel (1) is provided with a feed inlet (110) and a gas phase outlet (120). The gas phase outlet (120) is connected to the storage tank (3) through the heat exchanger (2). The top of the storage tank (3) is connected to the negative pressure pump (4). The bottom of the distillation vessel (1) is provided with a drain port (130).

2. The dichloroethane recovery system in the production of methyl thiophanate according to claim 1, characterized in that, The storage tank (3) is also connected to a separation tank (5), the light phase outlet of the separation tank (5) is connected to the water storage tank (501), and the heavy phase outlet of the separation tank (5) is connected to the dichloroethane collection tank (502).

3. The dichloroethane recovery system in the production of methyl thiophanate according to claim 2, characterized in that, The separation box (5) is equipped with a stirring unit, including a motor (510), a connecting rod (520), a stirring tube (530), a first bevel gear (540), and a second bevel gear (550); The motor (510) is located on the top of the outside of the separation box (5). The first bevel gear (540) is connected to the output end of the motor (510) through the connecting rod (520). The first bevel gear (540) and the second bevel gear (550) are vertically meshed. The second bevel gear (550) is sleeved on the outside of the stirring tube (530). The stirring tube (530) extends vertically into the inside of the separation box (5). A stirring paddle (5301) is provided on the outside of the stirring tube (530). The stirring tube (530) is a hollow tube, and the top of the stirring tube (530) is connected to the demulsifier storage tank (6) through a pipeline.

4. The dichloroethane recovery system in the production of methyl thiophanate according to claim 3, characterized in that, The stirring tube (530) includes an upper straight tube (531), a middle telescopic tube (532) and a lower straight tube (533) connected in sequence. The stirring tube (530) is located inside the separation box (5) and symmetrically arranged on both sides are telescopic cylinders (560). The fixed end of the telescopic cylinder (560) is connected to the upper straight tube (531) through the first fixing plate (561), and the telescopic end of the telescopic cylinder (560) is connected to the lower straight tube (533) through the second fixing plate (562).

5. The dichloroethane recovery system in the production of methyl thiophanate according to claim 4, characterized in that, The bottom of the lower straight pipe (533) is horizontally connected to a conduit (570), and multiple nozzles (571) are connected to the conduit (570).

6. The dichloroethane recovery system in the production of methyl thiophanate according to claim 3, characterized in that, The side wall of the separation box (5) is provided with a transparent viewing window (580).

7. The dichloroethane recovery system in the production of methyl thiophanate according to claim 6, characterized in that, The water storage tank (501) is connected to the heat exchange medium inlet of the heat exchanger (2) through the water supply pipeline (710), and the heat exchange medium outlet of the heat exchanger (2) is connected to the water storage tank (501) through the return water pipeline (720).

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