Chemical compatibility - heat exchanger

[noteye]

I'm working on a project that involves cooling concentrated sulfuric acid (~98%) on the tube side of a heat exchanger. The cooling media on the shell side can either be chilled water or refrigerated trichloroethylene (TCE). My question is, if I use the TCE so I can have cooler acid, what sort of problems can I expect if I have a leak that mixes TCE and sulfuric acid? Am I likely to have hydrolysis of the TCE? I have to decide if the benefit of cooler acid is worth the potential risks of a leak. The pressures are such that the TCE would leak into the acid.

Thanks in advance for the help.

 

[MJCronin]

noteye,

Leaks in S&T TEMA-type heat exchangers most commonly occur at the juncture between the tube and the tubesheet. This joint is usually rolled and/or seal welded,

You should consider a "double tubesheet" design for this heat exchanger application. A double tubesheet design uses two tubesheets with a gap between to insure no mixing between the two streams. Instrumented leak detection can be installed in the gap to notify of leakage of either stream.

The cost can be up to 80% more than a standard S&T design.

Since you are cooling hot acid, this design will not be cheap. A possible alternative would be a plate & frame unit with premium gasket materials...

What is your flowrate and temperature ?

MJC

 

[Montemayor]

noteye:

I'm going to assume you are working in a USA location; and if I'm correct, then you should be warned that you are putting the cart before the horse with you query.

For Process Safety Management and Management of Change, you must prepare for a HazOp - as a minimum requirement. In doing so, you have to confront and address the obvious safety concerns that will immediately jump right up at you:

1) What can happen to the equipment, process, piping and the chemicals themselves in the Sulfuric Acid stream should trichloroethylene get into this stream? Only you can answer this question. Your company (or you should have all the information about the chemicals you produce and work with in your process environment. OSHA holds you directly responsible for knowing this information and designing around it.

2) We on this Forum don't know what other weak or hazadous devices or possibilities exist in your process. Again, only you can answer this question.

3) You haven't stated if this is a retrofit project or a new application. But regardless, you must have done some preliminary design work and research before proposing this application. Is this the stage you presently find yourself in? If so, you should study your as-built P&ID in order to identify all potentially affected equipment and flow streams.

4) You can certainly profit by MJCronin's advice on using a TEMA double tubesheet design heat exchanger; this is always a viable option to consider.

5) Depending on the risk and hazards involved, you can also employ an intermediate coolant stream instead of the trichloroethylene - something like a chemical compatible with the Sulfuric.

Art Montemayor
Spring, TX