兰州石化公司乙腈法抽提丁二烯工艺特点

中国石油兰州石化分公司采用自行开发的乙腈法建成了90kt/a抽提丁二烯装置,该方法的特点是:裂解C4在第一萃取精馏塔中深度抽提丁二烯,萃余C4中丁二烯的质量分数小于2×10-5;在第二萃取精馏塔的上部用精馏方法分离丁二烯中的乙腈,没有采用常规的水洗方法,简化了流程;脱重塔采用气相进料,减少了相变次数,节能效果明显。2008年,90kt/a乙腈法抽提丁二烯装置的丁二烯实际产量为101.4kt,丁二烯的质量分数为99.73%,其中总炔的质量分数为2.4×10-5,乙腈的质量分数为1.2×10-6,各项工艺指标都达到或超过设计要求。

Technological Features of Butadiene Extraction by Acetonitrile Method in Lanzhou Petrochemical Company

Extractive distillation process of 1,3-butadiene by acetonitrile method sucessfully applied in 90 kt/a extraction unit of Lanzhou Petrochemical Company was introduced.The characteristics of the process were mainly as follows:(1)after 1,3-butadiene was mostly extracted from C4 in first extractive distillation tower,the mass fraction of 1,3-butadiene left in C4 fraction was less than 2×10-5;(2)the process was simplified by using distillation to separate acetonitrile in 1,3-butadiene at the upper(solvent recycling) section of the second extractive distillation tower instead of extraction by water;(3) for the sake of reducing energy cost of the process,feedstock entering de-heavy tower was in vapor phase,which reduced the repeating of phase change and resulted in significant save of energy.