Production system for preparing formaldehyde, paraformaldehyde, methylal and hexamethylene tetramine from methanol

Abstract

The invention discloses a production system for preparing formaldehyde, paraformaldehyde, methylal and hexamethylene tetramine from methanol, and belongs to the technical field of compound preparation. A process includes the steps that S1 methanol is used as a raw material and is subjected to recovery to obtain a low-concentration formaldehyde solution through oxidation, and unrecovered formaldehyde mixed gas is absorbed by an absorption tower to obtain a light aldehyde solution; S2 methanol and the low-concentration formaldehyde solution are used as raw materials and sequentially processed bya resin reactor, a reaction tower, a rectification tower and a cooler to obtain methylal; S3 the low-concentration formaldehyde solution in the process S1 is concentrated by secondary evaporation toobtain a high-concentration formaldehyde solution, and the high-concentration formaldehyde solution is vacuum-dried to obtain paraformaldehyde; and S4 liquid ammonia is used as a raw material, after vaporization, the liquid ammonia reacts with the light aldehyde solution in the step S1, and evaporative crystallization, centrifugation and drying are performed to obtain hexamethylene tetramine. Theproduction system can improve the effective utilization of resources such as the raw materials, reduce the discharge of pollutants, reduce environmental pollution, effectively reduce the production cost of enterprises and improve economic benefits.

Description

technical field [0001] The invention relates to the preparation of formaldehyde, paraformaldehyde, methylal and hexamethylenetetramine, in particular to a production system for preparing the above substances with methanol as a raw material, belonging to the technical field of compound preparation. Background technique [0002] Formaldehyde, chemical formula HCHO or CHO, formula weight 30.03, also known as formaldehyde. Colorless gas, irritating odor, irritating to human eyes and nose. Formaldehyde is a popular chemical product with a wide range of uses, simple production process, and sufficient supply of raw materials. It is the backbone of the downstream product tree of methanol. The world's annual output is about 25 million tons, and about 30% of methanol is used to produce formaldehyde. However, formaldehyde is a low-concentration aqueous solution, which is not convenient for long-distance transportation from an economic point of view, so factories are generally set up n...

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Problems solved by technology

[0006] The production process of the above-mentioned substances will produce various waste gases, waste liquids, etc. For example, the formaldehyde obtained by the reaction of methanol and air in the formaldehyde production process cannot be completely absorbed, and there is still formaldehyde in the unrecovered components. If it is directly discharged to the outside, It will not only cause environmental pollution, but also reduce the utilization efficiency of raw materials, waste of resources, etc.; for example, in the process of methylal production, a large amount of cooling water will be generated when cooling the finished product of methylal. If water is discharged from the system, it will cause waste of heat

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