Overall mass transfer coefficients for absorbing dilute SO2 from air into aqueous NaOH can be substantially enhanced by___________________?
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Answer: A. Increasing the gas film co-efficient
Explanation
Absorbing dilute sulfur dioxide into aqueous sodium hydroxide involves a very fast reaction. Fast chemical reactions eliminate liquid film mass transfer resistance almost entirely. Gas film resistance becomes rate controlling, making gas film coefficient enhancements necessary. Mass transfer in gas absorption involves resistances from both gas and liquid film layers. Chemical reactions inside liquid phases can consume solutes rapidly and reduce liquid resistance. Overall mass transfer coefficients combine individual film resistances using standard resistance models.
Flue gas desulfurization systems use alkaline solutions to scrub sulfur dioxide pollutants effectively. Optimizing industrial scrubber designs requires identifying whether gas or liquid film resistance dominates. Environmental regulations mandate efficient sulfur dioxide removal from industrial combustion exhaust gases. Increasing liquid film coefficients has little impact when liquid resistance is already negligible. Increasing total pressure alters gas density but does not specifically target gas film resistance. Decreasing total pressure would expand gas volumes and hinder efficient pollutant absorption operations.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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