| 摘要 |
A process for removing dimethyl ether (DME) and methanol impurities from C4 hydrocarbon stream without substantial loss of C4 hydrocarbons by fractionating a C4 hydrocarbon stream containing DME and methanol at low levels, e.g., less than 5 wt.% to produce an overhead of about 20 to 40 volume % of the C4 stream, condensing the overhead, contacting the condensed overhead with about 1 to 5 volumes of water, thereby removing a portion of the DME and methanol from the C4 stream, returning substantially all of the C4 stream, except the small amount solubilized in the water, to the fractionation and flashing the solubilized DME and hydrocarbons from the water. The fractionation and extraction are preferably carried out at elevated pressures, e.g., 200 to 300 psig to avoid refrigeration of the overhead condensation. The flashing of the DME and hydrocarbons is carried out by reducing the pressure on the water, e.g. atmospheric pressure at a temperature in the range of 20.degree.C to 50.degree.C, leaving methanol in the water. The methanol can be removed by distillation or by contacting the methanol containing water stream with a large volume of a C4 stream whereby a portion of the methanol is extracted in the C4 stream. The methanol depleted stream can recycle to contact the condensed overhead from the fractionation thereby establishing a closed circuit water wash/methanol recovery system. //CRL.PAT//986.APP
|
