Bhaskaran:
You haven't told us what you are planning as the cooling fluid for this condenser application. Therefore, the use of fins on the cooling side is of little or no help if you are using cooling water or another liquid coolant. Fins are used to overcome the inherently bad film heat transfer coefficient given by gases and vapors. Unless you are trying to cool down a significant amount of carrier gas (Nitrogen), I wouldn't consider the use of fins.
I don't know what you mean by the term “Cryogenic” as used in this query. I suspect you mean to say that you would use a “customized” spiral tube heat exchanger with a “cryogen” (like liquid Nitrogen) as the cooling fluid. Please furnish specific information on what it is that you intend to describe. If you are condensing the solvent at relative ambient temperatures, why mention the word “cryogenic”? The cryogenic zone is normally defined as temperatures < -100 oC. The application of these extremes of temperature(s) requires very specialized and expensive equipment. If that is what you mean, fine; but please be specific in defining what you intend to apply so that we can make reasonable and accurate comments or recommendations.
Condensing with chilled cooling water or brine and using a conventional shell & tube (S&T) or a plate heat exchanger (PHE) is a normal way of recovering solvents such as Acetone and THF. It all depends on what vapor pressure you want to condense your solvent at – which will determine the dewpoint or solvent content in the exit carrier gas that usually goes out to atmosphere. A S&T unit is very easy to adapt to serve as a successful vent condenser for recovering solvent. A PHE is more difficult (& expensive) to modify in order to achieve good vapor / liquid separation in the unit and eliminate liquid entrainment in the exit stream. A PHE has a difficult "footprint" to work with while locating it in elevated locations and in piping it up. Additionally, you will find that a PHE inherently depends for a large degree of its success in its multiple gaskets. And it is precisely these gaskets which sometimes form an "Achilles Heel" for the unit. Solvents inherently are difficult and troublesome to contain using some conventional gasket materials. Therefore, special gaskets might be required and some leakage may have to be tolerated. It depends on the solvent and the installation. I have never applied a PHE as a vent condenser. All my vent condensers have been S&T or special spiral coil units.
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Topic: solvent with inert (Read 5255 times)