优化C4原料生产低硫MTBE并回收二硫化物的方法探讨

Discussion of producing MTBE with low sulfur content and recovering bisulfides by optimizing C4 feedstock

关键词:  MTBE  硫含量  C₄馏分  二硫化物  C₄馏分分割塔  二硫化物分馏塔 

Key words:  MTBE  sulfur content  mixed C₄ fraction  bisulfide  C₄ fractionator  RSSR fractionator

摘要:

探讨了一种生产低硫MTBE产品并回收二硫化物的方法。根据C₄馏分中各组分及硫杂质沸点的不同,将其送入1台C₄馏分分割塔中,塔顶分出的是作为MTBE装置原料的轻C₄馏分；侧线抽出重C₄馏分,主要含C₅、顺丁烯、乙硫醇、异丙硫醇等较重组分,抽出量占C₄馏分总量的8%～15%；在侧线抽出板的下层塔板上设二硫化物循环进料线,主要用于解决C₄馏分中二硫化物含量小、塔底液位控制困难的问题；分割塔塔底出料为二硫化物,被送至经过特别设计的间歇操作二硫化物分馏塔,分离出二甲基二硫和二乙基二硫混合物,用作化工原料或产品。经处理后的轻C₄馏分已不含C₅及乙硫醇等重硫化合物,故可保证以其为原料生产的MTBE中总硫质量分数降至10 mg/kg以下。该方法具有工艺简单、不需要外部吸附剂或吸收剂、无新增三废污染等优点。 

Abstract:

A method of producing MTBE product with low sulfur content and recovering bisulfides(RSSR) was discussed. Based on the boiling point differences of the components and sulfides in the mixed C₄ fraction, mixed C₄ fraction were sent to a fractionator to separate the light C₄ fraction and heavy C₄ fraction. The top products were routed to MTBE unit as light C₄ fraction, while the heavy C₄ fraction were drawn as side product, which mainly contained C₅, cis butylene, ethanethiol, iso-propanethiol, etc. The heavy C₄ fraction account for about 8%-15% of the total mixed C₄ fraction ration. A RSSR recycling feedback line was set on just beneath the lowest side-draw tray of the fractionator mainly to solve the problem of bottom level control due to the small amount of RSSR. The bottom products(mainly RSSR) were sent to a RSSR fractionator, which was specially designed and operated batchwise. Dimethyl-bisulfides and diethyl-bisulfides were separated in the fractionator and used as chemical raw materials or chemical products. The treated light C₄ fraction contains no heavy sulfides such as C₅ or ethanethiol, so that the total sulfur content of the MTBE produced by the treated light C₄ fraction was decreased to below 10 mg/kg. The method has advantages of simple process, no need of outside adsorbents or absorbents, and no additional waste emissions.