Dear Colleagues, I am designing

[lcms]

Dear Colleagues,

I am designing a vaccuum destilation system for removing one volatile monomer from a latex through a steam stripping vertical column with trays.

Above the column I have included a foam trap vessel with a demister in order to avoid the foam (developed by monomer evaporation in the latex) to reach the condenser above the column. I have also included a defoamer device to spray a defoamer agent activated by a Level Switch high (LSH) on the top tray in order to prevent the foam to reach the foam trap, but I will be probably not allowed to use it to avoid latex properties impairing. My present observation is that the foam reach the condenser very frequently, even when the system shut down the vacuum pump when the foam level in the foam trap vessel reaches LSHH. Therefore I am thinking about installing a ESD valve betweem the foam trap and the condenser to guarantee that the foam never enters the condenser (when the foam enter the condenser tubes, the condenser is clogged very fast and we have to inteerup the operation to clean all the sysstem).

My only problem is that the ESD diameter will have to be very large (14") and it must be very, very expensive since we are used to specify ball valves for this kind of application (ESD) in column vapor pipes in order to be sure it will be tight (avoiding leakages).

Do you have any ideas to prevent the foam to reach the condenser with not so expensive approaches?

Thanks in advance.

 

[horacio Torres]

Have you thought about parallel plates, to promote foam breaking. Like is it done in the gas oil separation process????

 

[don1980]

I would design an emergency shutdown that is activated at the onset of foaming, on the trays prior to it reaching the overheads line and the condenser. Be aware too that detecting excessive tray foaming is needed in order to achieve the necessary separation of the volatile monomer. If the foam on one tray reaches the tray above, then you're not going to be getting separation of the constituents. Design the ESD to take actions such as shutting off the heat source and/or raising the column pressure when excessive tray foaming is detected.