In a binary distillation column, if the entering feed consists of 40 mole % vapor, what will be the slope of the resulting q-line_________________?
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Answer: C. -1.5
Explanation
The feed q-line slope is defined mathematically as q divided by the quantity q minus one. With forty percent vapor, the liquid fraction q equals sixty percent or 0.6. Dividing 0.6 by negative 0.4 yields the correct q-line slope of negative 1.5. The q parameter represents the fraction of liquid in the incoming feed stream. Feed thermal condition dictates whether the q-line is vertical, horizontal, or sloped. Intersection of the q-line with equilibrium curves helps locate the optimal feed tray location.
Distillation column design calculations require precise feed quality inputs to model rectifying sections. Petroleum fractionators handle feeds with varying vapor fractions during multi-stream processing. Feed preheaters adjust thermal conditions to optimize the q-line slope for minimum energy use. Positive slope values violate standard feed line equations for partially vaporized liquid feeds. Incorrect fractions or arithmetic errors produce erroneous slopes like positive 1.5 or 0.6. Vertical lines represent saturated liquid feeds where q equals one and the slope approaches infinity.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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