06-CHEM-43

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• 06-CHEM-43
• 06-CHEM-35
• 06-CHEM-15
• 06-CHEM-81

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Calculation of evaporator surface
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Problem statement

• 10,000 lb/hr of distilled water is required from
  untreated water.steam is available at 300oF , and
  the condenser will vent to the atmosphere. How
  much surface is required.?

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Assumptions

• Pressure drop through the condenser and lines of
  about 5psi.
• The saturation temperature in the evaporator
  shell will be 19.7psia or 226oF.

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Heat Balance
Q m? H

• Qevap10,0009619,610,000 Btu/hr
• Q300oF10,5509109,610,000 Btu/hr

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Temperature head

• ?t 300 226 74oF

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Overall coefficient

• From Fig.14.7 at a heat head of 74oF and a vapor
  temperature of 226 oF , the coefficient is 86.5
  of base .
• Using a base of 700 Btu/(hr)(ft2)
• UD 7000.865 605

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Surface area

• A Q/(UD)(?t)
• 9,610,000/(605)(74)
• 2150 ft2

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Reference

• Chapter 14 , D . Q. KERN