Reaction device of dimethyl phosphite

Abstract

The utility model discloses a dimethyl phosphite reaction device, which comprises an esterification kettle, a phosphorus trichloride feed pipe and a methanol feed pipe are inserted into the esterification kettle and are connected with a nozzle of a hedging reaction area, and a bottom discharge port of the hedging reaction area is connected with a mixed reaction area. The device has the beneficial effects that (1) two raw materials can be fully contacted through atomizing and spraying, so that the yield of dimethyl phosphite reaches more than 96%; (2) chloromethane gas and other gas phases can be separated from dimethyl phosphite through a gas-liquid separator, so that the generation of monomethyl phosphite and phosphorous acid is reduced; (3) a mixing element is arranged in the mixing reaction area, so that phosphorus trichloride which is not completely reacted can be rapidly mixed and reacted, and gas is discharged from an exhaust hole; (4) the method has the advantages that the materials can fully react, tail gas is quickly separated, and the esterification vacuum degree requirement can be reduced from-0.09 Mpa to-0.05 Mpa; and (5) the total retention time of the materials is short, backmixing is avoided, the total amount of reaction liquid held in unit time is small, and the safety is good.

Description

Technical Field

[0001] The utility model belongs to the technical field of dimethyl phosphite production equipment, and particularly relates to a device for dimethyl phosphite reaction. Background Art

[0002] Dimethyl phosphite is a very important chemical intermediate, and is a raw material for preparing pesticides such as glyphosate and trichlorfon. At the same time, it can also be used as a raw material for organic corrosion inhibitors, dye additives, plastic auxiliaries and flame retardants. Dimethyl phosphite is generally prepared by the reaction of phosphorus trichloride and methanol. The reaction is rapid and exothermic, and by-products such as methyl chloride and hydrogen chloride are generated at the same time. There are many side reactions in this reaction process, and the reaction process and conditions are complex. Therefore, improving the effective conversion rate of dimethyl phosphite and reducing the occurrence of side reactions are of great significance to China's agrochemical industry.

[0003] In the existing dimethyl phosphite production process, the raw materials of phosphorus trichloride and methanol enter the esterification kettle through the material counterflow of the feed pipe and continue to react, and then enter the deacidification kettle through the overflow pipe. Because there is no mixing element in the esterification kettle, the material mixing is not sufficient in this process. To ensure full reaction, methanol needs to be added in excess, and at the same time, it is necessary to extend the residence time of the material in the kettle and accumulate a certain amount of reaction liquid. The product dimethyl phosphite comes into contact with hydrogen chloride gas, resulting in an increase in side reactions. Summary of the Invention

[0004] In view of the problems existing in the above-mentioned prior art, the utility model provides a reaction device for dimethyl phosphite, which strengthens the mixing process of phosphorus trichloride and methanol, makes phosphorus trichloride and methanol fully contact, and at the same time removes hydrogen chloride gas during the reaction mixing process, reduces the side reactions of dimethyl phosphite products, reduces the consumption of methanol during the reaction process, reduces the reaction residence time compared with the original process, does not need to accumulate reaction liquid, and improves the reaction yield. The technical solution is: including an esterification kettle, a phosphorus trichloride feed pipe and a methanol feed pipe are inserted into the esterification kettle and connected to the nozzle of the counterflow reaction zone, and the bottom discharge port of the counterflow reaction zone is connected to the mixing reaction zone.

[0005] As a preferred solution, a tail gas pipeline is provided at the top of the esterification kettle.

[0006] As a preferred solution, the top gas outlet of the counterflow reaction zone is connected to the inlet of the gas-liquid separation zone. A gas-liquid separator is provided in the gas-liquid separation zone, and a pressure relief hole is provided on the outer wall of the gas-liquid separator.

[0007] As a preferred solution, the inside of the mixing reaction zone is filled with mixing fillers, and exhaust holes are provided on the outer wall of the mixing reaction zone.

[0008] As a preferred solution, the spray angle of the nozzle is α°, and the value range of α is 30° - 120°.

[0009] As a preferred embodiment, a jacket layer is provided on the outer wall of the esterification kettle, a coolant inlet is provided at the bottom of the jacket layer, and a coolant outlet is provided at the top thereof.

[0010] As a preferred embodiment, the nozzles in the countercurrent reaction zone are symmetrically arranged.

[0011] Advantages of the present utility model:

[0012] (1) By atomizing and injecting phosphorus trichloride and methanol in this device, the two raw materials can be fully contacted and react quickly, and the yield of dimethyl phosphite can reach over 96%;

[0013] (2) Chloromethane gas and the remaining gas phase pass through the gas-liquid separator, and can be quickly separated from dimethyl phosphite, reducing the generation of methyl phosphite and phosphorous acid;

[0014] (3) Mixing elements are arranged in the mixing reaction zone, which can enable the unreacted phosphorus trichloride to be quickly mixed and reacted. The gas is discharged from the exhaust hole, and the material stays in the mixing reaction zone for a short time and will not be backmixed with the subsequent material, further reducing side reactions;

[0015] (4) The advantage of this device is that the materials can fully react and the tail gas can be quickly separated, which can reduce the requirement for esterification vacuum degree. It can be reduced from -0.09 Mpa to -0.05 Mpa, avoiding excessive vaporization of methanol, increasing the tail gas condensation load, and reducing energy consumption;

[0016] (5) The overall residence time of the materials in this device is short, the materials do not undergo backmixing, continuous production can be carried out, and the total amount of reaction liquid held per unit time is small, with good safety. Description of the drawings

[0017] Figure 1 It is a schematic diagram of the overall structure of the present utility model.

[0018] In the figure: 1. Esterification kettle; 2. Phosphorus trichloride feed pipe; 3. Methanol feed pipe; 4. Countercurrent reaction zone; 401. Nozzle; 5. Mixing reaction zone; 501. Mixing filler; 502. Exhaust hole; 6. Gas-liquid separation zone; 601. Gas-liquid separator; 602. Pressure relief hole; 7. Tail gas pipeline; 8. Jacket layer; 801. Coolant inlet; 802. Coolant outlet. Detailed implementation manners

[0019] The following further describes the present utility model in detail according to the drawings and specific embodiments.

[0020] Embodiment

[0021] As Figure 1A reaction device for dimethyl phosphite as shown includes an esterification kettle 1. A phosphorus trichloride feed pipe 2 and a methanol feed pipe 3 are inserted into the esterification kettle 1 and connected to a nozzle 401 in a counter-jet reaction zone 4. The bottom discharge port of the counter-jet reaction zone 4 is connected to a mixing reaction zone 5. The nozzle 401 is used to atomize and counter-jet phosphorus trichloride and methanol, enabling the two raw materials to come into full contact and react rapidly.

[0022] Further, a tail gas pipe 7 is provided at the top of the esterification kettle 1 for discharging hydrogen chloride and chloromethane gases.

[0023] Further, the top gas outlet of the counter-jet reaction zone 4 is connected to the inlet of a gas-liquid separation zone 6. A gas-liquid separator 601 is provided in the gas-liquid separation zone 6, and a pressure relief hole 602 is provided on the outer wall of the gas-liquid separator 601. Due to the rapid reaction in the counter-jet reaction zone 4, a large amount of rapidly generated gas will entrain droplets. The gas-liquid separator 601 is used for gas-liquid separation, and the pressure relief hole 602 is opened to prevent the pressure in the gas-liquid separation zone 6 from being too high.

[0024] Further, the interior of the mixing reaction zone 5 is filled with mixing packing 501, and exhaust holes 502 are provided on the outer wall of the mixing reaction zone 5. The unreacted materials in the counter-jet reaction zone 4 continue to react in the mixing packing 501 in the mixing reaction zone 5, and the generated gas is discharged through the exhaust holes 502.

[0025] Further, the spray angle of the nozzle 401 is α°, and the value range of α is 30° - 120°, preferably 60° - 100°.

[0026] Further, a jacket layer 8 is provided on the outer wall of the esterification kettle 1. A coolant inlet 801 is provided at the bottom of the jacket layer 8, and a coolant outlet 802 is provided at the top of the jacket layer 8. Chilled brine coolant is added into the jacket layer 8 to control the reaction temperature at about -15°C.

[0027] Further, the nozzles 401 in the counter-jet reaction zone 4 are symmetrically arranged. The symmetrically arranged nozzles 401 enhance the contact of the raw materials and make the reaction more complete.

[0028] With the above device, its operation process is as follows: Phosphorus trichloride and methanol are continuously transported by pumps, metered by mass flow meters, and injected into the countercurrent reaction zone 4 through the nozzle 401. After being injected through the nozzle 401, the materials become a solid conical spray, and are atomized and countercurrent to carry out a mixing reaction. The injection pressure can be controlled at 0.2 - 1.5 bar, and the injection angle of the nozzle 401 is preferably 60° - 100°. A large amount of gas generated here enters the gas-liquid separation zone 6 through the gas outlet for gas-liquid separation and is discharged through the tail gas pipeline 7. The remaining reaction liquid enters the mixing reaction zone 5 through the discharge port for sufficient mixing. The mixed packing filled in the mixing reaction zone 5 ensures sufficient reaction of the materials. An exhaust hole 502 is provided on the outer wall of the mixing reaction zone 5. Hydrogen chloride and chloromethane generated by the reaction are discharged through the exhaust hole 502 and enter the tail gas pipeline 7.

Claims

1. A reaction device for dimethyl phosphite, comprising an esterification kettle (1), characterized in that: The phosphorus trichloride feed pipe (2) and the methanol feed pipe (3) are inserted into the esterification kettle (1) and connected to the nozzle (401) of the counter-reaction zone (4); the bottom discharge port of the counter-reaction zone (4) is connected to the mixing reaction zone (5).

2. A reaction device for dimethyl phosphite according to claim 1, characterized in that: A tail gas pipeline (7) is arranged on the top of the esterification kettle (1).

3. A reaction device for dimethyl phosphite according to claim 1, characterized in that: The top gas outlet of the counter-reaction zone (4) is connected to the gas inlet of the gas-liquid separation zone (6), a gas-liquid separator (601) is arranged in the gas-liquid separation zone (6), and a pressure relief hole (602) is arranged on the outer wall of the gas-liquid separator (601).

4. A reaction device for dimethyl phosphite according to claim 1, characterized in that: The interior of the mixing reaction zone (5) is filled with a mixed filler (501), and an exhaust hole (502) is provided on the outer wall of the mixing reaction zone (5).

5. A reaction device for dimethyl phosphite according to claim 1, characterized in that: The spray angle of the nozzle (401) is α°, and the value range of α is 30°-120°.

6. A reaction device for dimethyl phosphite according to claim 1, characterized in that: The outer wall of the esterification kettle (1) is provided with a jacket layer (8), the bottom of the jacket layer (8) is provided with a coolant inlet (801), and the top of the jacket layer (8) is provided with a coolant outlet (802).

7. A reaction device for dimethyl phosphite according to claim 1, characterized in that: The nozzles (401) of the counter-reaction zone (4) are symmetrically arranged.

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