Cocurrent flow process for the manufacture of sodium sulfite and bisulfite solutions

摘要

Sodium (bi)sulfites are produced by the steps of:P P(a) introducing a stream of aqueous sodium carbonate into the top end of a main packed column reactor;PP(b) introducing a stream of sulfur dioxide gas into the top end of the main packed column reactor concurrently with the stream of aqueous sodium carbonate;P P(c) allowing the aqueous sodium carbonate and sulfur dioxide to cocurrently flow downward from the top end of the main packed column reactor to the bottom of the column in a cocurrent flow, during which flow reaction occurs between the aqueous sodium carbonate and the sulfur dioxide to produce sodium (bi)sulfite; andPP(d) recovering the product sodium (bi)sulfite and a gas stream containing any excess sulfur dioxide from the bottom of the main packed column reactor. The product (bi)sulfite can be separated from the gas stream in a separate receiving vessel and then the gas is sent to a scrubber to remove residual SO.sub.2. The scrubber may be a second packed column reactor operating with cocurrent flow.