The overhead reflux drum for a vacuum column in an oil refinery operates at 25 mmHg. The

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The overhead reflux drum for a vacuum column in an oil refinery operates at 25 mmHg. The overhead temperature is 120°F, and the composition and flowrate of the vapor in the vent gas (not including any air leaks) isH = 1.2 lb/h CH4 = 20 lb/h CH6 = 45 lb/h C3H8 = 25 lb/h

The vacuum tower and associated equipment and pipes have an approximate volume of 21,000 ft3.

Answer the following:

1. Estimate the air leak into this (“tight”) system.

2. Determine how many stages would be required for a steam ejector to remove the vent gas plus the air leak into the system and deliver it to a vent gas handling system operating at 1.2 bar.

3. Estimate the amount of low-pressure steam (70 psig saturated) required by each stage of ejector assuming there is no intermediate condensation.

4. If cooling water is available at 86°F and must be returned to the cooling tower at 104°F, determine if a partial condenser could be employed and where it should be placed. Also determine if more than one condenser could be employed.

5. Determine the amount of steam required if a single partial condenser is used. You should assume that the condenser is placed between the last two stages of the ejector and a temperature approach of 10°F is used.

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Analysis Synthesis And Design Of Chemical Processes

ISBN: 9780134177403

5th Edition

Authors: Richard Turton, Joseph Shaeiwitz, Debangsu Bhattacharyya, Wallace Whiting

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