10-08-2012, 04:47 PM
Distillation Column
[attachment=31026]
CHOICE BETWEEN PLATE AND PACKED COLUMN
The choice between use of tray column or a packed column for a given mass transfer operation should, theoretically, be based on a detail cost analysis for the two types of contactors. However, the decision can be made on the basis of a qualitative analysis of relative advantages and disadvantages, eliminating the need for a detailed cost comparison.
PLATE CONTACTORS:
Cross flow plate are the most commonly used plate contactor in distillation. In which liquid flows downward and vapours flow upward. The liquid move from plate to plate via down comer. A certain level of liquid is maintained on the plates by weir.
Liquid flow arrangement:
In order to find liquid flow arrangement first find maximum liquid volumetric flow rate
So liquid flow rate =
(Liquid mass rate)/ (3600) (Liquid density)
Max Liquid Rate Is At the bottom of column so using "Lm" values
So Maximum liquid flow rate = 0.005 m3/sec
So from fig11.28 Coulson & Richardson 6th volume 3rd edition cross flow single pass plate is selected
Check Residence Time:
Sufficient residence time should be allowed in the downcomer for the entrained vapors to disengage from liquid stream to prevent aerated liquid being carried under the downcomer.
[attachment=31026]
CHOICE BETWEEN PLATE AND PACKED COLUMN
The choice between use of tray column or a packed column for a given mass transfer operation should, theoretically, be based on a detail cost analysis for the two types of contactors. However, the decision can be made on the basis of a qualitative analysis of relative advantages and disadvantages, eliminating the need for a detailed cost comparison.
PLATE CONTACTORS:
Cross flow plate are the most commonly used plate contactor in distillation. In which liquid flows downward and vapours flow upward. The liquid move from plate to plate via down comer. A certain level of liquid is maintained on the plates by weir.
Liquid flow arrangement:
In order to find liquid flow arrangement first find maximum liquid volumetric flow rate
So liquid flow rate =
(Liquid mass rate)/ (3600) (Liquid density)
Max Liquid Rate Is At the bottom of column so using "Lm" values
So Maximum liquid flow rate = 0.005 m3/sec
So from fig11.28 Coulson & Richardson 6th volume 3rd edition cross flow single pass plate is selected
Check Residence Time:
Sufficient residence time should be allowed in the downcomer for the entrained vapors to disengage from liquid stream to prevent aerated liquid being carried under the downcomer.