PURIFICATION OF HYDROCARBON

摘要

PURPOSE:To recover heat, condense a steam stream and return the condensed steam, by taking the steam stream as a side stream out of a plate near a raw material feed plate of an acetonitrile concentrating and recovering column in separating and purifying butadiene and isoprene using a mixed solvent of acetonitrile and water as an extracting solvent. CONSTITUTION:Butadiene and isoprene are separated and purified from a 4-5C hydrocarbon mixture in high purity using a mixed solvent of acetonitrile-water as an extracting solvent by an extractive distillation method. In the process, a stream stream is taken out of a plate near a raw material feed plate of an acetonitrile concentrating and recovering column as a side stream to recover heat. The stream stream is then condensed and returned to the plate from which the side stream is taken out. Thereby the heat recovery of high quality is carried out without impairing the water balance of the extracting solvent system. The heat recovery ratio can be further improved by dividing the acetonitrile concentrating column into the lower part 2 and the upper part 3 respectively connecting the steam stream and liquid stream and operating the upper part under a low pressure and the lower part under a high pressure.