SOLVENT REFINING METHOD FOR ISOCYANATE PREPARED BY PHOSGENE METHOD AND DEVICES USED IN SAME

Disclosed are a solvent refining method for isocyanate prepared by the phosgene method and multistage absorbing towers used in same. Solvent to be refined which contains water, iron, and/or phosgene , hydrogen chloride and other materials with color is dealt by the present method and multistage absorbing towers, which can effectively prevent a drying agent from absorbing water and hardening, partial overheating in the tower and generating channeling. Meanwhile, the pressure drop is effectively lowered. In addition, the content of water is ≤ 50 ppm, the content of iron is ≤ 5 ppm, the content of phosgene and hydrogen chloride is ≤ 20 ppm, Pt-Co chroma is ≤ 20 in the refined solvent. Therefore, the refined solvent can be used as the solvent for preparing isocyanate in the phosgene method and remarkably improve an L color of isocyanate. According to the method of the invention, by refining solvents and recycling use, solvent consumption is largely reduced, production cost is lowered, the technology operability i