A preparation method of a pyramidation system and dihaxyxyxyxyxic acid

Abstract

The application discloses a carbonylation feeding system and a method for preparing dimethyl oxalate, including a heat exchanger, the first cold air outlet of the heat exchanger communicates with the raw material inlet of the carbonylation reactor, and a preheater , the second cold air inlet of the preheater is used for feeding raw materials, the second cold air outlet of the preheater communicates with the first cold air inlet of the heat exchanger, and the first product inlet of the heat exchanger communicates with the carbonylation reactor The second product outlet of the preheater is connected to the hot fluid channel of the preheater for the high temperature medium to pass through, and the arrangement of the preheater is additionally added so that the low temperature raw material gas is passed into the preheater for preheating and then passed into the heat exchanger , the heated raw material gas exchanges heat with the high-temperature carbonylation product in the heat exchanger, so that the temperature of the high-temperature carbonylation product is kept above the melting point after heat exchange, and the crystallization of the carbonylation product is avoided and attached to the inner wall of the heat exchange tube.

Description

technical field [0001] The application relates to the field of carbonylation reaction equipment, specifically a carbonylation feeding system and a preparation method of dimethyl oxalate. Background technique [0002] In the preparation technology of dimethyl oxalate, the required reaction raw materials include methyl nitrite gas, which is also called esterification gas. CO and low-temperature esterification gas are mixed to form raw material gas, which is supplied to the reaction The temperature in front of the equipment is relatively low, generally around 10°C, and the raw material gas needs to be heated to about 115°C before passing into the carbonylation reactor. In the prior art, the raw material gas at about 10°C is mixed with the carbonylation product (about Dimethyl oxalate) directly conducts heat exchange in the heat exchanger, so that the temperature of the raw material gas rises from 10°C to about 115°C. During this process, since the melting point of dimethyl oxal...

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Problems solved by technology

[0002] In the preparation technology of dimethyl oxalate, the required reaction raw materials include methyl nitrite gas, which is also called esterification gas. CO and low-temperature esterification gas are mixed to form raw material gas, which is supplied to the reaction The temperature in front of the equipment is relatively low, generally around 10°C, and the raw material gas needs to be heated to about 115°C before passing into the carbonylation reactor. In the prior art, the raw material gas at about 10°C is mixed with the carbonylation product (about Dimethyl oxalate) directly conducts heat exchange in the heat exchanger, so that the temperature of the raw material gas rises from 10°C to about 115°C. During this process, since the melting point of dimethyl oxalate is 54°C, the local position The temperature of dimethyl oxalate at the place drops rapidly from 130°C to below the melting point, and dimethyl oxalate will crystallize in the heat exchange tube of the heat exchanger. As the crystallization amount of dimethyl oxalate in the heat exchange tube increases, resulting in The flow resistance of dimethyl oxalate in the heat exchange tube increases, and the crystallization of dimethyl oxalate adheres to the inner wall of the heat exchange tube, which directly leads to a significant decrease in the heat exchange efficiency of the heat exchanger, which in turn prevents the temperature of the raw gas from rising to the design temperature , which seriously affects the normal progress of the reaction in the carbonylation reactor, which requires maintenance of the heat exchanger after shutdown, disassembly of the heat exchange tube, cleaning or replacement of the heat exchange tube, not only the carbonylation reaction cannot be carried out, but also seriously affects the production rhythm , and it is very troublesome to clean or replace the heat exchange tubes, which increases the maintenance cost of production equipment

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