Distillation: processes – separatory – Plural distillations performed on same material – One a distillation under positive pressure or vacuum
Patent
1996-03-19
1998-02-17
Bhat, Nina
Distillation: processes, separatory
Plural distillations performed on same material
One a distillation under positive pressure or vacuum
203 83, 203 85, 203 96, 203DIG23, B01D 300, B01D 310
Patent
active
057188106
ABSTRACT:
A method for recovering methanol from sulfur-based wood pulping process vapors, which contain at least methanol and dimethyl disulfide. The method involves three steps. The first step consists of introducing the vapors into a first distillation tower at a vapor introduction point. The second step consists of introducing water into the first tower at a point above the vapor introduction point. The third step consists of heating liquid which is in the first tower below the vapor introduction point so that a liquid stream flows from the bottom of the first tower and a gas stream flows from the top of the first tower. The liquid stream contains most of the methanol originally in the vapors. The gas stream contains most of the dimethyl disulfide originally in the vapors. The liquid stream can then be distilled in a second distillation tower by conventional distillation to produce dry methanol. The first and third steps can be combined by introducing sufficiently heated vapors. When the vapors contain more than sixty percent water, then there need be only two steps. The first step consists of introducing the vapors into a first distillation tower at a vapor introduction point. The second step consists of heating liquid which is in the first tower below the vapor introduction point so that a liquid stream flows from the bottom of the first tower and a gas stream flows from the top of the first tower.
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Landon Von G.
Robbins Lanny A.
Bhat Nina
The Dow Chemical Company
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