METHOD AND APPARATUS FOR PRODUCING ACETIC ACID WITH HIGH EFFICIENCY Russian patent published in 2012 - IPC C07C51/44 C07C53/08 C07C51/12 

FIELD: chemistry.

SUBSTANCE: invention relates to improved carbonylation methods for producing acetic acid, one of which involves: (a) carbonylation of methanol or reactive derivative thereof in the presence of water, a catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, a promoter from methyl iodide to form a reaction mixture with acetic acid in a reactor; (b) separating the stream of the reaction mixture with acetic acid into a liquid recirculation stream and a first stream of the crude product which contains acetic acid; (c) feeding the first stream of crude product into a column for distillation of light fractions; (d) distillation of the stream of crude product to remove low-boiling components as the overhead product and form a first stream of the purified product in form of a side stream and a liquid residual stream, the liquid residual stream primarily consisting of acetic acid, where the first stream of purified product is fed into a dehydration column, after which the dried product is fed into a column for distillation of heavy fractions, and acetic acid is collected in form of an overhead product from the column for distillation of heavy fractions; (e) evaporating at least a portion of the liquid residual stream to obtain a second product stream; and (f) feeding the second product stream after condensation or compression thereof for further processing after merging with the first stream of purified product into said dehydration column. The invention also relates to an apparatus for producing acetic acid, comprising: (a) a reactor for carbonylation of methanol or reactive derivatives thereof in the presence of water, a catalyst selected from rhodium catalysts, iridium catalysts and mixtures thereof, and a promoter from methyl iodide to form a reaction mixture with acetic acid in the reactor; (b) a flash evaporation apparatus connected to the reactor and configured for inlet of the stream of the reaction mixture and separation thereof into (i) a liquid recirculating stream and (ii) a crude first product stream containing acetic acid; (c) a column for distillation of light fractions, which is connected to the flash evaporation apparatus which is configured for separation of low-boiling components in form of an overhead product from the first product stream and formation of a first stream of purified product in form of a side stream, and a liquid residual stream; (d) a dehydration column connected to the column for distillation of light fractions; (e) a column for distillation of heavy fractions connected to the dehydration column; and (f) an evaporation reservoir, also connected to the column for distillation of light fractions, for evaporation of at least a portion of the liquid residual stream and configured to feed a second product stream into the dehydration column; or a column for distillation of the liquid residual stream to form a stream of the purified product and meant for feeding it into the dehydration column or into the column for distillation of heavy fractions, where the column for distillation of the liquid residual stream is a stripping column. The apparatus and methods of producing acetic acid thus involve extraction of the product from the residue of light fractions in a stripping column and feeding the extracted acid for further processing in order to increase efficiency of the system.

EFFECT: reduced load on the column for distillation of light fractions; the load on the dehydration column can also be reduced in the embodiment, wherein further removal of water from the extracted acid is not necessary.

15 cl, 4 dwg, 2 tbl