05-12-2012, 11:46 AM
Design of Spray column with Chemical Reaction
[attachment=42565]
Problem
To reduce the impurity (A) level in an organic liquid from 10000ppm to 500ppm using an aqueous solvent containing a solute (B) which reacts with A following the rate equation
Approach
Case 1- The rate of chemical reaction is very slow as compared to rate of mass transfer
Case 2- The rate of mass transfer is comparable to the rate of chemical reaction
Case 3- The rate of chemical reaction is very high as compared to rate of mass transfer
Case 1
As the rate of chemical reaction is very low as compared to rate of mass transfer the concentration profile will be as below
Assumption
The dispersed phase mass transfer co-efficient is very high as compared to continuous phase mass transfer co-efficient
Hence, resistance to mass transfer on the dispersed side is neglected
Calculations
Calculate minimum flow rate for aqueous liquid from given data
Assume flow rate of aqueous liquid higher than the minimum value calculated
Calculate u0
Calculate dp
Calculate Φf
When the phases are interchanged
When water is the continuous phase, due to Morongani effect we consider only regimes 3 and 4
Calculations similar to the previous case
Continuous phase mass transfer is the controlling mechanism
[attachment=42565]
Problem
To reduce the impurity (A) level in an organic liquid from 10000ppm to 500ppm using an aqueous solvent containing a solute (B) which reacts with A following the rate equation
Approach
Case 1- The rate of chemical reaction is very slow as compared to rate of mass transfer
Case 2- The rate of mass transfer is comparable to the rate of chemical reaction
Case 3- The rate of chemical reaction is very high as compared to rate of mass transfer
Case 1
As the rate of chemical reaction is very low as compared to rate of mass transfer the concentration profile will be as below
Assumption
The dispersed phase mass transfer co-efficient is very high as compared to continuous phase mass transfer co-efficient
Hence, resistance to mass transfer on the dispersed side is neglected
Calculations
Calculate minimum flow rate for aqueous liquid from given data
Assume flow rate of aqueous liquid higher than the minimum value calculated
Calculate u0
Calculate dp
Calculate Φf
When the phases are interchanged
When water is the continuous phase, due to Morongani effect we consider only regimes 3 and 4
Calculations similar to the previous case
Continuous phase mass transfer is the controlling mechanism