Question
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Please suggest ways of reducing steam demand in our sour water stripper.
Jun-2021
Answers
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Marcello Ferrara, ITW Technologies, mferrara@itwtechnologies.com
Sour water stripping is considered a ‘fouled service’, in particular for phenolic sour water. Among the foulants, the ones that have the greatest impact on steam consumption are hydrocarbons and polymers.
The most common fouling is hydrocarbon based, which occurs when large volumes of hydrocarbons are carried over into SWS feed. Hydrocarbons tend to agglomerate inside the equipment and form a sludge that accumulates in the heat exchangers and in the bottom of the tower, thereby directly impacting steam consumption.
It is also common for phenolic water (for instance, from the FCC unit and DCU) to contain polymer precursors which create polymeric fouling inside the unit.
In general, polymer fouling may include: amine degradation and oxidation products; red oil fouling (which frequently occurs in olefin caustic treatment); peroxides formed by the oxidation of various components (which are initiators of polymerisation reactions); olefins, in particular conjugated diolefins (which form polymers or gums in the presence of oxygen traces); thiophenes and thiophenols (which may form gum-like substances in the presence of oxygen and diolefins) and phenols (which form insoluble crosslinked polyphenols in the presence of corrosion products).
Polymeric fouling will seriously contribute not only to increased steam consumption, but to unit performance by creating high delta P.
ITW can address both of the sludge and polymeric fouling issues by applying patented ITW Online Cleaning or ITW Onstream Cleaning technologies.
Jun-2021
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