Solvent recovery from a gellable stream 1

[pjharder]

I have a waste solvent/polymer stream that purges accumulated branched polymer from a process. Would like to recover solvent from waste polymer to reduce volume but doing so will invariably result in gelling of the stream. Could someone recommend equipment or technology that will enable stripping of Hydrocarbon solvent from a pumpable liquid through the gel stage? The gooey stage is what I anticipate is the most difficult to overcome.

Ideal endpoint would be to remove all solvent leaving a more handleable solid. Would a votator be applicable to this type of application? I am not familiar with the technology but ran across it in a description of gelatin manufacture.

Thanks for any cross functional ideas.

 

[bchoate]

bchoate
The info given does not indicate whether you have a suspension or a solution of polymer in waste solvent. If it is a solution, then something like a flash devolatilization system may be applicable. The solution is heated in a heat exchanger designed to quickly heat the solution. The solution is pumped through a head with several orifices in it (like a shower head). The result is solvent vapor overhead and a foam in the flash tank. A gear pump such as a Maag or Witte that can handle the foam is needed to consolidate the foam and pump it out of the vessel. The vessel is operated at reduced pressure. A single stage can get the solvent down to 2% if there isn't more than about 30% in the feed. This is very common operation in polystyrene plants.

 

[pjharder]

Thank you, BChoate.

Yes, it is a polymer solution in ~80% solvent. I have considered the flash option. I'm anticipating some difficulty though with the formation of gel in the residual stream. We know that if we allow the branching fraction to exceed a few % in the solution, either through accumulation in the polymer/solvent loop, or removal of the solvent, it forms a non-pumpable liquid gel. This has caused entire system plugging in the past when we haven't paid close enough attention to the concentration of branching in the process.

Flashing is an option, but I need a piece of equipment that can handle the formation of these solids without causing reliability problems.