Example Calculations for Developing Operating Window

Sieve trays have wide applications due to lower capital cost and less maintenance required. However, valve trays can promote froth regime and thus achieve distillation efficiency up to 20% higher than sieve trays (Anderdson et ah, 1976). Furthermore, valve trays can achieve 3 1 turndown compared to sieve trays in 2 1. However, the disadvantages of valve trays are higher pressure drop and cost. 

The following example is designed with the purpose of enhancing the understanding of column tray design, operation window and the capacity limits. 

The overall tray design procedural guideline is to get the tray diameter and spacing right first with consideration of spray and tray flooding, and then size the 

Slopy or easy fractionation if outside of this range. If unexpected L/V is obtained, review the t apor and liquid loading Valve tray is better in supressing ray than sieve tray 

75-77% for vacuum towers 80-85% for Dornial towers 65-77% fOT small tower It is the height of froth 80% instead of clear liquid bei t 

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EXAMPLE CALCULATIONS FOR DEVELOPING OPERATING WINDOW Thus, for a given Whc = 21.5 ft/s, 4i becomes... 

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