Reducing amine circulation rate

[Sina]

Hello
In our plant we use DEA to treat sour gas. our sour feed gas has 3000 PPM H2S and 1.7 mol% CO2.
gas flow rate is about 7000 m3/hr. Amine rate is almost 330 m3/hr (calculated from known formula and simulation software).outlet gas has 0.18 mol% CO2 and 1 ppm H2s. As you know the outlet gas is far from specification (CO2 2mol% and H2S 4 ppm), so we want to reduce amine circulation rate. I think due to amine rate reducing we encounter to an increase in amine loading and maybe flooding. how much we can reduce amine rate?
I appreciate it if anyone help me to solve this solution.

 

[georgeverghese]

Decreasing solvent circulation rate does not result in column flooding; increasing the solvent rate does (root cause of which is downcomer backup in a plate column).

In the case of a packed bed type column, the decreased flow should be above the min flow required for adequate packing wetting.

 

[Sina]

Dear georgeverghese
thank you for your time and reply. Do you think we should decrease amine rate by experience? because the existing formula cant satisfy our aim

Thank you in advance

 

[georgeverghese]

The formula you may be using now probably is too conservative ( from GPSA ?) to represent reality - you could try Pro / II or PROSIM to simulate this operation to get a better approach to reality. Pro/II also has a an amines package which includes DEA.

To decide if you should decrease amine circulation rate, the following may help to give you some direction

a)Do you have any up surge in flow beyond 7000m3/h?
b)Is there some reduction in utility heating demand ( fuel gas or other) or is it neutral when you decrease amine recirc rate?