醋酸乙烯装置乙醛精馏塔中乙醛聚合原因分析及改造措施

研究了醋酸乙烯合成反应器换触媒后开车初期乙醛精馏塔D1运行恶化问题,发现生成的一种较强酸促使乙醛聚合生成三聚乙醛,三聚乙醛引起醋酸乙烯和水形成W/O型微乳而将水带至醋酸乙烯精馏塔,使醋酸乙烯水解生成乙醛,导致精醋酸乙烯产品中乙醛超标。进一步深入探讨了这种强酸的可能种类是盐酸或丙炔酸。采取在D1进料中加碱中和酸从而破坏乙醛发生聚合反应的条件,防止该塔堵塞,减少带到醋酸乙烯精馏塔中的水量,确保精醋酸乙烯产品中乙醛含量达标。

Causes and prevention of polymerization of acetaldehyde in rectifying tower in vinyl acetate plant

The problems existing in the acetaldehyde rectifying tower D1 during the startup of the vinyl acetate reactor after catalyst replaced were analyzed.It was found that a strong acid induced polymerization of acetaldehyde to form paraldehyde which caused water and vinyl acetate to form W/O type micro-emulsion.Consequently water was brought to vinyl acetate rectifying tower,which caused hydrolization of vinyl acetate into acetaldehyde.This was the reason for acetaldehyde content in the product over the standard of refined vinyl acetate.It was further found that the strong acid was hydrochloric acid or propiolic acid.To prevent the polymerization of acetaldehyde,a measure of adding alkali into the inlet feed of D1 to neutralize the strong acid was adopted.The results indicated that jam of the packed tower D1 was successfully avoided and the content of acetaldehyde in the refined vinyl ac-etate product was satisfactorily controlled within the standard code.