A water washing system for methyl isocyanate production
By designing a water washing system to separate chloroform and HCl, the problem of material waste in existing technologies has been solved, achieving efficient recovery and purity improvement of chloroform and promoting the preparation of methyl isocyanate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-01
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies cannot effectively separate and recover chloroform and HCl, resulting in material waste and affecting the preparation of methyl isocyanate.
A water washing system for methyl isocyanate production was designed, including a water washing tank and a solvent recovery tank. By setting up multiple valves and pipelines, the system can separate and recover chloroform and HCl separately. After washing with deionized water, chloroform enters the mixing tank and HCl enters the tail gas acid tower.
This improved the purity of chloroform, reduced material waste, and facilitated the subsequent preparation of methyl isocyanate.
Smart Images
Figure CN224541719U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of methyl isocyanate preparation technology, and in particular to a water washing system for methyl isocyanate production. Background Technology
[0002] Methyl isocyanate is an organic synthesis intermediate used to synthesize polymers such as polyisocyanates, polyurethanes, and polyurea resins, as well as technical materials such as carbaryl and methomyl. The production process of methyl isocyanate is mainly divided into three sections: acyl chloride section, methyl isocyanate section, and tail gas section. (1) Acyl chloride (N-methylcarbamoyl chloride) section: Phosgene and monomethylamine are heated and metered by hot oil and then enter the synthesis tube, where they react fully to produce acyl chloride. The acyl chloride is cooled by a condenser and then mixed with the circulating liquid (from the methyl isocyanate section) before going to the methyl isocyanate section. The synthesis tail gas goes to the tail gas section. (2) Methyl isocyanate synthesis section: The mixture from the acyl chloride section is evaporated and decomposed by a decomposer. The decomposed gas is condensed by a condenser and then purified and separated in a purification tower. The gas at the top of the purification tower is condensed in a condenser to obtain the intermediate product methyl isocyanate, which is then used in the technical material synthesis workshop. The trichloromethane (containing a small amount of methyl isocyanate) separated from the refining tower overflows from the tower bottom and is recycled to the acyl chloride section. The tail gas (containing trichloromethane) from the refining tower is absorbed by the bubbling of the cold tail gas tank and then sent to the tail gas section. (3) In the tail gas section, the tail gas after the acyl chloride decomposition gas is condensed by the condenser and the tail gas from the refining tower mainly contain hydrogen chloride and trichloromethane. The discharged tail gas is sent to the falling film absorber to absorb the solvent trichloromethane and HCl gas in the tail gas. After separation by the separator, the aqueous phase mainly contains HCl and 30% hydrochloric acid is produced. It is pumped to the hydrochloric acid storage tank for sale. The organic phase is the solvent trichloromethane and is sent to the acyl chloride synthesis section for recycling. However, trichloromethane still contains the by-product HCl. The current process cannot separate trichloromethane and HCl for separate recovery, resulting in material waste and affecting the preparation of methyl isocyanate. Utility Model Content
[0003] The purpose of this application is to provide a water washing system for the production of methyl isocyanate, in order to solve the problem that current processes cannot separate and recover chloroform and HCl separately, resulting in material waste and affecting the preparation of methyl isocyanate.
[0004] To solve the above-mentioned technical problems, this application provides a water washing system for methyl isocyanate production, comprising: The system includes a washing tank and a solvent recovery tank. One side of the solvent recovery tank is connected to one side of the washing tank via a feed pipe. A solvent recovery pump is installed on the feed pipe. The bottom of the washing tank is connected to the solvent recovery tank via a bottom return pipe. The solvent recovery tank is connected to the bottom of a stratification tank. A mixing tank is connected to the feed pipe near the washing tank. An overflow pipe is connected to the upper side of the washing tank. One end of the overflow pipe is connected to the tail gas acid tower. A deionized water delivery pipe is connected to the lower side of the washing tank. A bottom valve is installed on the bottom reflux pipe, control valves are installed on both the feed pipe and the deionized water delivery pipe, an overflow valve is installed on the overflow pipe, a gas-liquid balance pipe is installed between the solvent recovery tank and the stratification tank, and a gas phase balance pipe is installed between the top of the water washing tank and the bottom reflux pipe.
[0005] As a preferred embodiment, a methyl isocyanate production water washing system is provided, wherein a check valve is also provided on the deionized water delivery pipe.
[0006] As a preferred embodiment, a water washing system for methyl isocyanate production is provided, wherein both the bottom return pipe and the overflow pipe are equipped with sight glasses.
[0007] The solution requires detailed explanation of a water washing system for methyl isocyanate production, wherein the gas phase balance pipe is also equipped with a regulating valve and a sight glass.
[0008] The solution requires detailed explanation of a water washing system for methyl isocyanate production, wherein the overflow port on the water washing tank connected to the overflow pipe is more than 1.5 meters higher than the inlet of the tail gas acid tower.
[0009] The solution requires further explanation as to the fact that in a methyl isocyanate production water washing system, the deionized water delivery pipe is positioned at least 0.5 meters above the overflow port near the check valve.
[0010] Compared with the prior art, the methyl isocyanate production water washing system provided by this utility model includes a water washing tank and a solvent recovery tank. One side of the solvent recovery tank is connected to one side of the water washing tank through a feed pipe. A solvent recovery pump is installed on the feed pipe. The bottom of the water washing tank is connected to the solvent recovery tank through a bottom return pipe. The solvent recovery tank is connected to the bottom of the stratification tank. A mixing tank is connected to the feed pipe near the water washing tank. An overflow pipe is connected to the upper side of the water washing tank. One end of the overflow pipe is connected to the tail gas acid tower. A deionized water delivery pipe is connected to the lower side of the water washing tank. A bottom valve is installed on the bottom return pipe. Control valves are installed on both the feed pipe and the deionized water delivery pipe. An overflow valve is installed on the overflow pipe. A gas-liquid balance pipe is installed between the solvent recovery tank and the stratification tank. A gas phase balance pipe is installed between the top and bottom return pipes of the water washing tank. In use, the chloroform discharged from the bottom of the stratification tank after stratification enters the solvent recovery tank. Then, the control valve and overflow valve on the deionized water delivery pipe are opened, and the control valve on the delivery pipe is closed. When the liquid level in the solvent recovery tank reaches 80%, the solvent recovery pump is started, the control valve and overflow valve on the deionized water delivery pipe are closed, and the control valve on the delivery pipe is opened to send the chloroform in the solvent recovery tank into the washing tank for washing. When the liquid level in the solvent recovery tank reaches 80% again, the control valve and overflow valve on the deionized water delivery pipe are opened, the control valve on the delivery pipe is closed, the bottom valve is opened, and the chloroform is placed into the solvent recovery tank. The solvent recovery pump is started again to send the chloroform into the washing tank. Repeating the above steps completes the washing of the chloroform. The washed chloroform ultimately goes to the mixing tank, and the HCl goes to the tail gas acid tower via the overflow pipe. This allows for the separation and separate recovery of chloroform and HCl, improving the purity of the chloroform and benefiting the subsequent preparation of methyl isocyanate. Attached Figure Description
[0011] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0012] Figure 1 This is a schematic diagram of a water washing system for methyl isocyanate production provided in an embodiment of this application; In the diagram: 1. Washing tank; 2. Solvent recovery tank; 3. Feed pipe; 4. Recovered solvent pump; 5. Bottom reflux pipe; 6. Separation tank; 7. Mixing tank; 8. Overflow pipe; 9. Deionized water delivery pipe; 10. Bottom valve; 11. Control valve; 12. Overflow valve; 13. Gas-liquid balance pipe; 14. Gas phase balance pipe; 15. Check valve; 16. Sight glass; 17. Regulating valve. Detailed Implementation
[0013] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.
[0014] The core of this application is to provide a water washing system for the production of methyl isocyanate, which solves the problem that current processes cannot separate and recover chloroform and HCl separately, resulting in material waste and affecting hydrochloric acid preparation.
[0015] Figure 1 This is a schematic diagram of a water washing system for methyl isocyanate production provided in an embodiment of this application. See also... Figure 1 As shown.
[0016] A water washing system for methyl isocyanate production includes a water washing tank 1 and a solvent recovery tank 2. One side of the solvent recovery tank 2 is connected to one side of the water washing tank 1 via a feed pipe 3. A solvent recovery pump 4 is installed on the feed pipe 3. The solvent recovery pump 4 can pump chloroform in the solvent recovery tank 2 into the water washing tank 1 via the feed pipe 3. The bottom of the water washing tank 1 is connected to the solvent recovery tank 2 via a bottom return pipe 5. The solvent recovery tank 2 is connected to the bottom of a layering tank 6. The organic phase solvent chloroform after being layered in the layering tank 6 can enter the solvent recovery tank 2 from its bottom. A gas-liquid balance pipe 13 is installed between the solvent recovery tank 2 and the layering tank 6 to balance the pressure in the layering tank 6. A mixing tank 7 is connected to the feed pipe 3 near the washing tank 1. After washing, the high-purity chloroform enters the mixing tank 7. An overflow pipe 8 is connected to the upper side of the washing tank 1. One end of the overflow pipe 8 is connected to the tail gas acid tower. During the washing process, since HCl and chloroform are incompatible and chloroform has a high density, the chloroform at the bottom of the washing tank 1 is discharged into the solvent recovery tank 2, while the HCl and water at the top are discharged into the tail gas acid tower through the overflow pipe 8. A deionized water delivery pipe 9 is connected to the lower side of the washing tank 1. Deionized water is supplied to the washing tank 1 through the deionized water delivery pipe 9 for washing. A bottom valve 10 is installed on the bottom return pipe 5, and control valves 11 are installed on both the feed pipe 3 and the deionized water conveying pipe 9. An overflow valve 12 is installed on the overflow pipe 8. A gas phase balance pipe 14 is installed between the top and bottom return pipes 5 of the water washing tank 1. The pressure of the water washing tank 1 is balanced by the gas phase balance pipe 14, which facilitates the discharge of chloroform at the bottom into the solvent recovery tank 2.
[0017] Example 2 Based on Example 1, a methyl isocyanate production water washing system, in order to prevent backflow of deionized water, preferably, also has a check valve 15 installed on the deionized water delivery pipe 9.
[0018] Based on Example 1, a water washing system for methyl isocyanate production is provided, preferably with sight glasses 16 on both the bottom return pipe 5 and the overflow pipe 8 to facilitate observation of the material flow in the pipeline.
[0019] Based on Example 1, a water washing system for methyl isocyanate production is preferably provided with a regulating valve 17 and a sight glass 16 on the gas phase balance tube 14 to facilitate the control and observation of the gas in the gas phase balance tube 14.
[0020] Based on Example 2, in a methyl isocyanate production water washing system, to improve the washing effect, preferably, the overflow port connected to the overflow pipe 8 on the water washing tank 1 is more than 1.5 meters higher than the inlet of the tail gas acid tower. In this example, in a methyl isocyanate production water washing system, the deionized water delivery pipe 9 is located more than 0.5 meters higher than the overflow port near the check valve 15.
[0021] The present invention provides a water washing system for the production of methyl isocyanate, comprising a water washing tank 1 and a solvent recovery tank 2. One side of the solvent recovery tank 2 is connected to one side of the water washing tank 1 via a feed pipe 3. A solvent recovery pump 4 is installed on the feed pipe 3. The bottom of the water washing tank 1 is connected to the solvent recovery tank 2 via a bottom return pipe 5. The solvent recovery tank 2 is connected to the bottom of a stratification tank 6. A mixing tank 7 is connected to the feed pipe 3 near the water washing tank 1. An overflow pipe 8 is connected to the upper side of the water washing tank 1. One end of the overflow pipe 8 is connected to the tail gas acid tower. A deionized water delivery pipe 9 is connected to the lower side of the water washing tank 1. A bottom valve 10 is installed on the bottom return pipe 5. Control valves 11 are installed on both the feed pipe 3 and the deionized water delivery pipe 9. An overflow valve 12 is installed on the overflow pipe 8. A gas-liquid balance pipe 13 is installed between the solvent recovery tank 2 and the stratification tank 6. A gas phase balance pipe 14 is installed between the top and bottom return pipes 5 of the water washing tank 1. During use, the chloroform discharged from the bottom of the stratification tank 6 enters the solvent recovery tank 2. Then, the control valve 11 and overflow valve 12 on the deionized water delivery pipe 9 are opened, and the control valve 11 on the delivery pipe 3 is closed. When the liquid level in the solvent recovery tank 2 reaches 80%, the solvent recovery pump 4 is started, the control valve 11 and overflow valve 12 on the deionized water delivery pipe 9 are closed, and the control valve 11 on the delivery pipe 3 is opened to send the chloroform in the solvent recovery tank 2 into the washing tank 1 for washing. When the liquid level in the solvent recovery tank 2 reaches 80% again, the deionized water pump 4 is opened. Control valve 11 and overflow valve 12 on conveying pipe 9 are used to close control valve 11 on conveying pipe 3 and open bottom valve 10 to put trichloromethane into solvent recovery tank 2. Restart solvent recovery pump 4 to send trichloromethane into water washing tank 1. Repeat the above steps to complete the water washing of trichloromethane. The washed trichloromethane is finally sent to mixing tank 7. Before being put into mixing tank 7, a sample must be taken to confirm that it is qualified. HCl goes to tail gas acid tower through overflow pipe 8. Trichloromethane and HCl can be separated and recovered separately, which can improve the purity of trichloromethane and is beneficial to the subsequent preparation of methyl isocyanate.
[0022] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and incorporate common knowledge or customary techniques in the art disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this application is indicated by the claims.
[0023] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The embodiments of this application described above do not constitute a limitation on the scope of protection of this application.
Claims
1. A water washing system for the production of methyl isocyanate, characterized in that, include: A washing tank (1) and a solvent recovery tank (2) are provided. One side of the solvent recovery tank (2) is connected to one side of the washing tank (1) through a feed pipe (3). A solvent recovery pump (4) is installed on the feed pipe (3). The bottom of the washing tank (1) is connected to the solvent recovery tank (2) through a bottom return pipe (5). The solvent recovery tank (2) is connected to the bottom of a stratification tank (6). A mixing tank (7) is connected to the feed pipe (3) near the washing tank (1). An overflow pipe (8) is connected to the upper side of the washing tank (1). One end of the overflow pipe (8) is connected to the tail gas acid tower. A deionized water delivery pipe (9) is connected to the lower side of the washing tank (1). A bottom valve (10) is provided on the bottom return pipe (5), a control valve (11) is provided on the material conveying pipe (3) and the deionized water conveying pipe (9), an overflow valve (12) is provided on the overflow pipe (8), a gas-liquid balance pipe (13) is provided between the solvent recovery tank (2) and the stratification tank (6), and a gas phase balance pipe (14) is provided between the top of the water washing tank (1) and the bottom return pipe (5).
2. The water washing system for methyl isocyanate production according to claim 1, characterized in that, The deionized water delivery pipe (9) is also equipped with a check valve (15).
3. The water washing system for methyl isocyanate production according to claim 1, characterized in that, Both the bottom return pipe (5) and the overflow pipe (8) are equipped with sight glasses (16).
4. The water washing system for methyl isocyanate production according to claim 1, characterized in that, The gas phase balance pipe (14) is also equipped with a regulating valve (17) and a sight glass (16).
5. The water washing system for methyl isocyanate production according to claim 2, characterized in that, The overflow port on the water washing tank (1) connected to the overflow pipe (8) is more than 1.5 meters higher than the inlet of the tail gas acid tower.
6. The water washing system for methyl isocyanate production according to claim 5, characterized in that, The position of the deionized water delivery pipe (9) near the check valve (15) is more than 0.5 meters higher than the overflow port.