Product Description

Structural features:

Patented graphite esterification reactor--ZHJK series is a cooperation between our company and Sichuan Fuhua Pesticide Technology Co., Ltd. It is specially designed and manufactured for the esterification reaction section of the glyphosate production process. The equipment is composed of rectangular graphite head and graphite reaction. The heat exchanger, graphite distributor, graphite heat exchange block and the sealing gasket between them are composed of stacks. Because the heat exchange block only bears pressure and has a monolithic structure, there is no cemented seam, so the structure strength is high and the impact resistance is good. The side plates of the water seal are cast iron plates, which are easy to maintain and disassemble, and can also be made into a two-way anti-corrosion structure. The material flow of the equipment can be 1-4 flow.

product description:

In recent years, with the continuous expansion of the domestic production scale of the alkyl ester method glyphosate collar, the demand for dimethyl phosphite (trimethyl phosphite) has increased sharply, the production scale has continued to increase, and the annual production volume of each production line has exceeded It has realized industrial production and achieved large-scale production and operation; domestic manufacturers are developing production lines with an annual production capacity of 12,000 tons for each production line. This requires a large-scale production of dimethyl phosphite esterifier.

1. Process principle of dimethyl phosphite reaction

1) The reaction mechanism of phosphorous trichloride and methanol to form dimethyl phosphite is as follows:

PCl3+ CH3OH --CH3OPCl2 + HCl

CH3OPCl2 + CH3OH--(CH3O)2PCl + HCl

(CH3O)2PCl +CH3OH--(CH3O)3P +HCl

(CH3O)3P + HCl--(CH3O)2POH + CH3Cl

The intermediate product, trimethyl phosphite, is extremely unstable. As long as there is hydrogen chloride, it can react to produce dimethyl phosphite. In the total reaction, 2 mol of hydrogen chloride is generated, and the presence of hot hydrogen chloride can easily cause the following side reactions with dimethyl phosphite:

(CH3O)2POH + HCl--CH3OP(OH)2+ CH3Cl

CH3OP(OH) 2+ HCl--H3PO3+ CH3Cl

The higher the reaction temperature, the longer the time and the more side reactions. The reaction of phosphorus trichloride and methanol is a moment of strong exothermic reaction. The key to the tail gas recovery process is to create conditions where the two reactants are fully contacted, shorten the reaction time, effectively remove the heat of reaction, and remove the reaction products as much as possible In order to suppress the occurrence of side reactions, the esterification reaction is generally carried out in a spray reactor. Under vacuum conditions, phosphorus trichloride and methanol are sprayed into the reactor at right angles. The material leaving the jet reactor enters the mixing tank to continue the reaction, while the generated hydrogen chloride and methyl chloride gas are removed by vacuum. The reaction product is further vacuum-removed from hydrogen chloride and methyl chloride through a deacidification kettle, and then is separated and refined.

2) The esterification reactors of general manufacturers are made of enamel reactors, which are usually carried out in jet reactors. Under vacuum conditions, phosphorus trichloride and methanol are sprayed into the reactor at right angles, and the materials in the jet reactor are discharged. Enter the mixing kettle to continue the reaction.

2. Problems existing in enamel kettle as esterification reactor:

1) According to the reaction mechanism of phosphorous trichloride and methanol, the strong exothermic reaction requires that the reaction heat be transferred away thermally and instantaneously, producing a large amount of hydrogen chloride and methyl chloride gas at the same time. The enamel kettle used as an esterification reactor cannot transfer the reaction heat away as quickly as possible. The crude ester is concentrated at the bottom of the kettle, which affects the transfer of reaction heat, and the capacity of a single production line is limited; the production cycle is one cycle per kettle and cannot be continuous Production cannot form a 10,000-ton production capacity on a single production line.

2) There are serious safety hazards in using an enamel kettle as an esterification reactor.

3) The recovery rate of dimethyl phosphite produced by using an enamel kettle as an esterification reactor is low.

4) There are many side reactions when using an enamel kettle as an esterification reactor.

5) Use an enamel kettle as an esterification reactor. The hydrogen chloride and methyl chloride gas produced by the reaction of phosphorus trichloride and methanol is pumped away with a certain amount of semi-finished dimethyl phosphite.

3. Dimethyl phosphite esterification reactor made of block-hole graphite

1) Impermeable graphite is a non-metallic material that is both corrosion-resistant and thermally conductive. It has good corrosion resistance to most organics, inorganics, salts and solvents. The thermal conductivity is more than twice that of ordinary carbon steel. The coefficient of thermal expansion is small, and the temperature resistance is good. The structure is sturdy, not easy to break, and the heat transfer coefficient is higher than that of the tubular esterifier.

2) According to the reaction mechanism of phosphorus trichloride and methanol, the strong exothermic reaction requires that the heat of the reaction be transferred instantaneously, producing a large amount of hydrogen chloride and methyl chloride gas at the same time. With its good thermal conductivity, graphite can instantly take away the reaction heat through the heat exchanger, which is to take away the heat. The production process is a continuous process, and the capacity of a single production line reaches more than 10,000 tons.

3) The equipment production is safe and reliable.

4) Block-hole graphite dimethyl phosphite esterification reactor for the reaction of phosphorus trichloride and methanol reduces side reactions.

5) The special design of the block-hole graphite dimethyl phosphite esterification reactor allows the crude dimethyl phosphite to separate quickly from hydrogen chloride and methyl chloride. Phosphorus trichloride reacts with methanol to form dimethyl phosphite. The product is reduced, thereby increasing the recovery rate of dimethyl phosphite by 5-8%.

4. Structural characteristics of graphite esterification reactor

1) A graphite reactor and a graphite distributor are installed at the material inlet, so that the material reacts quickly and is evenly distributed on the through-hole wall of the heat exchange block material, so that the reaction heat can be exchanged with the cooling water at the fastest speed to achieve rapid cooling , The purpose of inhibiting the occurrence of side reactions.

2) The main material is impregnated graphite, which has good corrosion resistance and good thermal conductivity, which can realize instant heat exchange between the material and the cooling water, reduce the temperature of the material, and inhibit the occurrence of side reactions.

3) The heat exchange block has a compact structure and a fast heat exchange speed, which realizes the simultaneous reaction and heat exchange, so that the continuity of the production process becomes a reality, which is beneficial to increase the output.

4) The top plate, bottom plate and side plates are made of cast iron, which can effectively protect the graphite material and make up for the shortcomings of impregnated graphite as a brittle material that is afraid of collisions.

4. Application manufacturer: Sichuan Fuhua Pesticide Technology Co., Ltd. 8 sets

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