Kremser Brown equation - Gas absorbers

[georgeverghese]

In a simplified version of this equation, we have :

Fraction of solute in exit gas as a ratio to that in the incoming gas = (A-1) / ((A^(N+1)) - 1)

Where the LHS = y2 / y1 in this simplifed form of the KSB equation ( which is valid for low values of y, and low values of the same solute in the feed lean solvent, and absorption is more or less isothermal)

Where y2 = solute mole fraction in exit gas ; y1 = solute mole fraction in incoming gas

A = absorption factor ; N= no of theoretical stages

There is an alternate presentation of this KSB equation which give N explicitly without going through a trial and error calc.

Does some one have the explicit alternate presentation for A? Thanks in advance for sharing.

 

[EmmanuelTop]

For diluted systems, Absorption factor is considered constant and the corresponding calculation of the required number of stages is straightforward (see the links below)

http://www.separationprocesses.com/Absorption/GA_Chp05b.htm

http://www.separationprocesses.com/Absorption/MainSet2.htm

Can you share what is the system in question?

Dejan IVANOVIC
Process Engineer, MSChE

 

[georgeverghese]

Yes, the absorption factor is constant in these cases.

These attachments provide the value of N explicitly, while I am looking for the expression that gives A explicitly.

In a lean oil absorption tower, or a TEG tower, once the value of A is known for a given set of operating conditions (say from a process simulation), it is possible to rate the tower for more trays or less trays and determine the change in exit gas solute concentration.

Getting the value of A for a known set of operating conditions is the reason for this search for an explicit expression for A - it avoids the tiresome trial and error method to get this value.