Treatment device for solvent recovered by phosgenation reaction

Abstract

The utility model relates to a phosgenation reaction recovered solvent treatment device which is characterized in that two ends of a porous pipeline are connected with flange pup joints, an organic phase filter is embedded in the porous pipeline, a water molecule reverse osmosis membrane is covered on the lower half circumference of the surface of the porous pipeline, and a Buchner funnel is correspondingly arranged below the porous pipeline. A bottom discharge pipe of the Buchner funnel is connected into a water molecule storage tank below the Buchner funnel, a bottom outlet of the Buchner funnel is correspondingly provided with the water molecule storage tank, the lower part of one side of the Buchner funnel is connected with a vacuum suction filtration device through a pipeline, and water separated by the organic phase filter is sucked and filtered into the water molecule storage tank from a water molecule reverse osmosis membrane through a porous pipeline under the vacuum action; the water enrichment in the treatment process is avoided. And the recovered solvent can be directly used without pre-distillation treatment, so that the production cost and the energy consumption are reduced. The device is small in size, flexible and convenient to install, capable of being applied to other reaction systems needing water removal and impurity removal, and high in applicability.

Description

Technical Field

[0001] The utility model belongs to the field of chemical technology equipment, and specifically relates to a phosgenation reaction solvent recovery processing device. Background Art

[0002] Phosgenation is the process of introducing carbonyl chloride (-COCl) or carbonyl groups into organic molecules using phosgene as a raw material. Phosgene is a colorless, non-flammable, highly toxic gas at room temperature and pressure. It is heavier than air and slightly soluble in water, but readily soluble in organic solvents such as toluene, xylene, chlorobenzene, and o-dichlorobenzene. It easily liquefies at low temperatures or under pressure. However, the phosgenation process typically operates under high temperature and pressure, causing phosgene to exist in a gaseous state. To ensure production safety and a more thorough phosgenation reaction, a solvent is typically used to absorb it before the reaction proceeds.

[0003] Taking the production process of salicylonitrile as an example, toluene, which can dissolve phosgene, is usually used as a dispersant and absorbent. After the reaction is completed, the unreacted excess phosgene is absorbed by the tail gas absorption device, and then the phosgene is removed from the solvent and recycled. This process has the following problems: First, the water content in the recovered solvent is too high. During the photochemical reaction, the introduced phosgene will first react with the water in the solvent to produce carbon dioxide and hydrogen chloride. At the same time, hydrogen chloride is very soluble in water to form hydrochloric acid, resulting in the waste of phosgene, the generation of by-products and the corrosion of the reaction equipment; (2) The method of recovering the solvent to treat the water in the solvent is distillation separation, which requires high heat, resulting in energy waste, increased production costs and incomplete treatment of the water in the solvent; (3) The recovered solvent usually contains impurities, which will affect the purity of the product and the reaction process. Therefore, it is necessary to dehydrate and remove impurities from the solvent before the phosgenation reaction to ensure the progress of the phosgenation reaction and the safety of production. Summary of the Invention

[0004] The purpose of the utility model is to overcome the problems existing in the prior art and to provide a phosgenation reaction solvent recovery processing device with universal applicability.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a phosgenation reaction solvent recovery processing device, characterized in that: both ends of the porous pipe are connected to the flange short-circuit, the organic phase filter is embedded in the porous pipe, the lower half of the surface of the porous pipe is covered with a water molecule reverse osmosis membrane, and a Büchner funnel is installed correspondingly below the porous pipe. The discharge pipe at the bottom of the Büchner funnel is connected to the water molecule storage tank below it, and a water molecule storage tank is set corresponding to the bottom outlet of the Büchner funnel. The lower part of one side of the Büchner funnel is connected to a vacuum filtration device through a pipe, and the water separated by the organic phase filter is filtered from the water molecule reverse osmosis membrane into the water molecule storage tank through the porous pipe through the vacuum action, avoiding the enrichment of water during the treatment process; the front end flange short-circuit is connected to the recovery solvent inlet, and the rear end flange short-circuit is connected to the recovery solvent outlet.

[0006] The diameter of the pore structure on the surface of the porous pipe is 0.1-10 cm; the material thereof is enameled pipe, 304 stainless steel or 316 stainless steel.

[0007] The organic phase filter is a baffle filter, which is composed of a plurality of baffles; the baffles are connected to the porous pipe through buckles; the organic phase filter for screening water molecules and recovered solvents is composed of an organic phase filter membrane.

[0008] The organic phase filter membrane is composed of one or more of ethersulfone membrane (PES) folded filter membrane, polytetrafluoroethylene (PTFE) folded filter membrane, nylon membrane (N6 / N66) folded filter membrane, polyvinylidene fluoride membrane (PVDF) folded filter membrane, mixed cellulose membrane (MCE) folded filter membrane, polypropylene (PP) folded filter membrane, and glass fiber (GF) folded filter membrane.

[0009] The Buchner funnel is connected to the bottom surface of the porous pipe through a buckle, and a sealing gasket is provided at the bottom connection; a valve is installed on the discharge pipe at the bottom of the Buchner funnel.

[0010] The water molecule reverse osmosis membrane is an RO membrane with a pore size of 0.0001 μm.

[0011] The flange short-circuit is lined with a polytetrafluoroethylene (PTFE) lining to facilitate sealing and prevent volatilization of the recovery solvent.

[0012] The flange short-circuit is made of 304 stainless steel, fiberglass, or 316 stainless steel.

[0013] The vacuum filtration device is a vacuum pump.

[0014] Compared with the prior art, the advantages of this utility model are:

[0015] (1) A multi-stage atmospheric filtration device was designed to reduce the water content in the recovered solvent in stages; the recovered solvent can be used directly without prior distillation treatment, reducing production costs and energy consumption.

[0016] (2) The filter device with segmented baffle structure can not only remove water but also isolate impurities in the recovered solvent. The segmented structure is connected to the pipeline by a buckle. If the filter membrane is blocked, one section can be directly removed and replaced, which is convenient for disassembly.

[0017] (3) A water recovery device was designed to extract water from the filtration system in a timely manner while the organic filter membrane filters the water phase, ensuring that water is not enriched.

[0018] (4) The setting of the filter membrane allows only water molecules to pass through and be discharged through the porous pipe, which can effectively remove impurities in the recovered solvent and ensure the safe and smooth operation of the phosgenation reaction.

[0019] (5) The utility model has a small size and is flexible and convenient to install. It can also be used in other reaction systems that require water removal and impurity removal, and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the utility model;

[0021] In the figure: 1-porous pipe, 2-flange short-circuit, 3-organic phase filter, 4-water molecule reverse osmosis membrane, 5-Buchner funnel, 6-water molecule storage tank, 7-vacuum filtration device. DETAILED DESCRIPTION

[0022] The present invention is explained below with reference to the accompanying drawings.

[0023] See Figure 1 A phosgenation reaction solvent recovery processing device features: a porous pipe 1 with flange shorting 2 connected at both ends. An organic phase filter 3 is embedded in the porous pipe 1. A water molecule reverse osmosis membrane 4 is coated around the lower half of the porous pipe 1. The water molecule reverse osmosis membrane 4 is an RO membrane with a pore size of 0.0001 μm. A Büchner funnel 5 is mounted below the porous pipe 1. The bottom outlet pipe of the Büchner funnel 5 connects to a water molecule storage tank 6 below it. The lower portion of the Büchner funnel 5 is connected to a vacuum filtration device 7, i.e., a vacuum pump, via a pipe. The water separated by the organic phase filter 3 is filtered through the porous pipe 1 through the water molecule reverse osmosis membrane 4 and into the water molecule storage tank 6, preventing water accumulation during the treatment process. The front flange shorting 2 connects to the recovered solvent inlet, and the rear flange shorting 2 connects to the recovered solvent outlet. The flange shorting 2 is lined with polytetrafluoroethylene (PTFE) for sealing and to prevent volatilization of the recovered solvent. The flange shorting 2 is made of 304 stainless steel, fiberglass reinforced plastic, or 316 stainless steel.

[0024] The Buchner funnel 5 is connected to the bottom surface of the porous pipe 1 through a buckle, and a sealing gasket is provided at the bottom connection; a valve is installed on the discharge pipe at the bottom of the Buchner funnel 5.

[0025] The diameter of the pore structure on the surface of the porous pipe 1 is 0.1-10 cm; its material is enameled pipe, 304 stainless steel or 316 stainless steel.

[0026] The organic phase filter 3 is a baffle filter, which is composed of a plurality of baffles; the baffles are connected to the porous pipe 1 through buckles; the organic phase filter 3 is composed of an organic phase filter membrane for screening water molecules and recovered solvent.

[0027] The organic phase filter membrane is composed of one or more of ethersulfone membrane (PES) folded filter membrane, polytetrafluoroethylene (PTFE) folded filter membrane, nylon membrane (N6 / N66) folded filter membrane, polyvinylidene fluoride membrane (PVDF) folded filter membrane, mixed cellulose membrane (MCE) folded filter membrane, polypropylene (PP) folded filter membrane, and glass fiber (GF) folded filter membrane.

[0028] The recovered solvent is a commonly used solvent for phosgenation reaction, including toluene, chlorobenzene, and o-dichlorobenzene.

[0029] The following is an example of producing salicylonitrile by phosgenation to explain the operation process of the present invention.

[0030] (1) After the pre-phosgenation process for producing salicylonitrile is completed, alkali is added to break the phosgenation reaction and the pH of the solution is adjusted to 8-9. Dilute hydrochloric acid is then added to adjust the pH of the solution to 2-3, causing salicylonitrile to precipitate in the form of crystals. The solution is allowed to stand to allow the toluene and water in the solution to separate. Testing shows that the water content of the undistilled toluene is >1000 ppm.

[0031] (2) The utility model is connected between the toluene pump outlet and the toluene pipeline through the flange short-circuit 2 at both ends, and the pump pressure of the toluene outlet pump is controlled at 0.05 MPa, so that the recovered toluene enters from the recovery solvent inlet.

[0032] (3) After the porous pipe 1 is filled with toluene, close the valve on the discharge pipe at the bottom of the Buchner funnel 5, open the vacuum filtration device 7, set the vacuum value of the vacuum pump to -0.1 MPa, and promptly extract the isolated water molecules from the porous pipe 1 and store them in the water molecule storage tank 6.

[0033] (4) Take a filtered toluene sample at the solvent outlet to ensure that the moisture content in the recovered toluene is less than 50 ppm.

Claims

1. A phosgenation reaction solvent recovery processing device, characterized in that: Both ends of the porous pipe (1) are connected to flange short-circuits (2), an organic phase filter (3) is embedded in the porous pipe (1), a water molecule reverse osmosis membrane (4) is covered on the lower half of the surface of the porous pipe (1), a Buchner funnel (5) is correspondingly installed below the porous pipe (1), a discharge pipe at the bottom of the Buchner funnel (5) is connected to a water molecule storage tank (6) below it, and a lower part of one side of the Buchner funnel (5) is connected to a vacuum filtration device (7) through a pipe; the front end flange short-circuit (2) is connected to the recovery solvent inlet, and the rear end flange short-circuit (2) is connected to the recovery solvent outlet.

2. The phosgenation reaction solvent recovery processing device according to claim 1, characterized in that: The porous pipe (1) has a surface pore structure with a diameter of 0.1-10 cm; and is made of enameled pipe, 304 stainless steel or 316 stainless steel.

3. The phosgenation reaction solvent recovery processing device according to claim 1, characterized in that: The organic phase filter (3) is a baffle-type filter, consisting of a plurality of baffles; the baffles are connected to the porous pipe (1) via buckles; the organic phase filter (3) is composed of an organic phase filter membrane for screening water molecules and recovered solvents.

4. A phosgenation reaction solvent recovery processing device according to claim 3, characterized in that: The organic phase filter membrane is composed of one or more of ethersulfone membrane (PES) folded filter membrane, polytetrafluoroethylene (PTFE) folded filter membrane, nylon membrane (N6 / N66) folded filter membrane, polyvinylidene fluoride membrane (PVDF) folded filter membrane, mixed cellulose membrane (MCE) folded filter membrane, polypropylene (PP) folded filter membrane, and glass fiber (GF) folded filter membrane.

5. The phosgenation reaction solvent recovery processing device according to claim 1, characterized in that: The Buchner funnel (5) is connected to the bottom surface of the porous pipe (1) via a buckle, and a sealing gasket is provided at the bottom connection; a valve is installed on the discharge pipe at the bottom of the Buchner funnel (5).

6. The phosgenation reaction solvent recovery processing device according to claim 1, characterized in that: The water molecule reverse osmosis membrane (4) is an RO membrane with a pore size of 0.0001 μm.

7. The phosgenation reaction solvent recovery processing device according to claim 1, characterized in that: The flange short-circuit (2) is lined with a polytetrafluoroethylene (PTFE) lining to facilitate sealing and prevent volatilization of the recovered solvent.

8. A phosgenation reaction solvent recovery processing device according to claim 1 or 7, characterized in that: The flange short-circuit (2) is made of 304 stainless steel, glass fiber reinforced plastic, or 316 stainless steel.

9. The phosgenation reaction solvent recovery processing device according to claim 1, characterized in that: The vacuum filtration device (5) is a vacuum pump.

Images