| 摘要 |
The retrofitting of an existing methanol or methanol/ammonia plant to make acetic acid is disclosed. The plant is retrofitted to feed carbon dioxide into a reformer to which natural gas and steam (water) are fed. Syngas is formed in the reformer wherein both the natural gas and the carbon dioxide are reformed to produce syngas with a large proportion of carbon monoxide relative to reforming without added carbon dioxide. The syngas is split into a first part and a second part. The first syngas part is converted to methanol in a conventional methanol synthesis loop that is operated at about half of the design capacity of the original plant. The second syngas part is processed to separate out carbon dioxide and carbon monoxide, and the separated carbon dioxide is fed back into the feed to the reformer to enhance carbon monoxide formation. The separated carbon monoxide is then reacted with the methanol to produce acetic acid or an acetic acid precursor by a conventional process. Also disclosed is the separation of hydrogen which is reacted with nitrogen, in a conventional manner, to produce ammonia. Also disclosed is the reaction of a portion of the acetic acid in a conventional manner with oxygen and ethylene to form vinyl acetate monomer. The nitrogen for the added ammonia capacity in a retrofit of an original methanol plant comprising an ammonia synthesis loop, and the oxygen for the vinyl acetate monomer process, are obtained from a new air separation unit. |
