Slag removal method for continuous production of methyl isocyanate

Abstract

The invention discloses a deslagging method for continuous production of methyl isocyanate. The method comprises the following steps: installing a deslagging machine below an air and liquid separator; performing air and liquid separation on a methyl isocyanate solution obtained by reaction by using the air and liquid separator; condensing a gas phase component and then rectifying and purifying to obtain a methyl isocyanate product; putting a liquid phase component in the deslagging machine and automatically removing tripolymethyl isocyanate solid slags; and returning the rest unreacted methyl carbamyl chloride, a trichloromethane solvent and a small amount of the methyl isocyanate product to a liquid mixing tank from the outlet of the deslagging machine and further reacting. The method disclosed by the invention can be used for automatically removing solid slags generated in the continuous production of the methyl isocyanate, realizing integration of deslagging and dry-recycle by adopting the deslagging machine, completely preventing direct contact between toxic materials and a person, reducing the labor strength, reducing toxication accidents, effectively evaporating residual volatile components such as raw materials, products and solvents in the solid slags and increasing the total yield of the products and the recycle rate of the solvents.

Description

technical field [0001] The invention relates to a slag removal method for the continuous production of methyl isocyanate. Background technique [0002] Methyl isocyanate is an important pesticide intermediate, mainly used in the synthesis of carbamate pesticides, such as: carbofuran, methomyl, amethomyl, isoprocarb (Yechansan), secbucarb (Barba Sand), carbaryl, propoxur, Haoanwei, thiodicarb, carbosulfan, butylthiuron, etc. [0003] At present, most domestic production of methyl isocyanate uses phosgene and methylamine as raw materials to prepare methyl carbamoyl chloride (abbreviated as MCC), and then in the presence of an inert solvent such as chloroform, methyl carbamoyl chloride is decomposed and rectified to produce formazan base isocyanate (abbreviated as MIC). The existing production process of methyl isocyanate will produce polymer solid slag. Currently, a slag steaming kettle is generally used to remove the polymer solid slag generated in the production process, a...

AI Technical Summary

Problems solved by technology

[0004] 1) The solid slag produced in the production process of methyl isocyanate must be manually opened to remove the slag, and the slag contains more than 20% of volatile components such as methyl carbamoyl chloride, methyl isocyanate and solvents, not only It is highly irritating and toxic. Workers must be fully equipped with anti-virus weapons to operate under high temperature and toxic and stimulating conditions. The labor intensity is high and there is a risk of poisoning;

[0005] 2) In order to reduce the harm to the human body, the production site generally uses water washing to decompose part of the methylcarbamoyl chloride and methyl isocyanate contained in the slag, which causes waste of water resources, burden of wastewater treatment, and hydrochloric acid generated by hydrolysis corrodes the equipment and a series of problems, and the slag still contains some volatile components such as methyl carbamoyl chloride, methyl isocyanate and solvents to cause environmental pollution;

[0006] 3) The solid residue containing volatile components such as methyl carbamoyl chloride, methyl isocyanate and solvent enters into incineration, resulting in increased production costs

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