A dilute aqueous stream at 10 Kg.s-1 needs heating using steam condensate at 95°C available at 10 Kg.s-1 via a 1-1 shell and tube exchanger. The optimal setup is_______________?
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Answer: A. Counter flow with process stream on shell side
Explanation
Counter flow arrangements maximize the log mean temperature difference between hot and cold streams. Placing the process stream on the shell side provides larger flow area and accommodates higher flow rates. This configuration ensures optimal heat recovery and thermal effectiveness in single pass exchangers. Shell and tube exchangers offer greater flexibility in surface area arrangement and fluid placement. Counter flow ensures the lowest possible approach temperature between entering and exiting fluids. Fluid placement decisions balance pressure drop limitations against convective heat transfer coefficients.
Chemical plants prioritize counter flow heat exchangers to maximize energy recovery and minimize steam usage. Placing corrosive or fouling process fluids on the shell side facilitates mechanical cleaning access. Optimizing exchanger configurations reduces operating costs and improves overall thermodynamic efficiency. Parallel flow configurations limit the outlet temperature of the cold fluid to the hot fluid outlet. Placing the process stream inside the tubes increases pressure drop without improving shell advantages. Ignoring flow direction optimization leads to oversized exchangers and poor thermal performance.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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