优化C_4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 C_4 feedstock

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10mg/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。

A method of producing M TBE product with low sulfur content and recovering bisul-fides(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 .T he trea-ted light C4 fraction contains no heavy sulfides such as C 5 or ethanethiol ,so that the total sulfur content of the M TBE 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 .