Stripper off gas handling
Foul condensates are reprocessed in the evaporation stripper system, whereby volatile compounds are driven by so called stripper off gas while the condensate is purified in the stripper column. Generated stripper off gas contains relatively high levels of methanol and TRS and can in most cases be destroyed as it is in the lime kiln or in the CNCG incinerator. The handling of stripper gas means that relatively large amounts of gas and steam need to be handled, where the main disadvantages are primarily that the stripper gas cannot be accumulated, but also that the stripper off gas destruction usually requires the supply of fossil support fuel. Installing a Methanol system, the methanol is concentrated into a concentrated liquid fuel while most of the stripper gas water content is removed, resulting in a higher fuel value so that fossil support fuel is avoided. Unlike stripper off gas, can liquid methanol be temporarily stored, which gives the pulp mill increased flexibility and reduced risk of venting.
MISTAB provides complete systems for the extraction of liquid methanol from stripper off gas and can in most cases also offer efficient process solutions for the replacement of individual equipment in existing stripper and methanol systems.