Study On Acetic Acid Production By PVA By-product Methyl Acetate

Acetic acid is one of the most widely used organic monoacids.The industrial production technology of acetic acid mainly includes the following four routes:liquid light hydrocarbon oxidation method,acetaldehyde oxidation method,ethylene oxidation method,methanol carbonylation method(high pressure or low pressure).Sinopec Great Wall Energy and Chemical(Ningxia)Co.,Ltd.has a design capacity of 300,000 tons per year for acetic acid plant.Due to the shortage of carbon monoxide in the upstream unit,the current capacity can only reach 190,000 tons per year.The PVA by-product methyl acetate to acetic acid capacity expansion project is based on the existing plant,using the refined by-product methyl acetate of PVA process as raw material,new methyl acetate batching system,optimization of methanol,methyl acetate,water feeding route;the heat balance and water balance of the plant has changed,we need to optimize and adjust the process operation parameters;increasing the capacity of acetic acid plant by gradually increasing the feed quantity of methyl acetate,and then saving energy and reducing consumption;containing impurities of acetaldehyde,acetone and vinyl acetate in the raw material of methyl acetate,the influence of the quality change of methyl ester raw material on acetic acid plant is studied and the solution is proposed.The capacity expansion of acetic acid from methyl acetate was successful,but the density of heavy phase in the stratifier was lower than that before adding methyl acetate.At the same time,the corrosion of the distillation system was serious,and the catalyst system contained a lot of metal ions.The removal of trace alkanes in the reaction system and the heavy phase was removed by operating a dealkane column.Catalyst regeneration in the catalyst unit takes time to remove metal ions and the lithium loss rate as a catalyst promoter is high.The adsorption of metal ions by cation resin is proposed.