Toluene/xylene Condenser

[TBP]

I have to select a heat exchanger for a vent condenser using cooling tower water. Of course, the people who need this done have almost no information. They just know that they need a vent condenser. Depending upon what they're doing with the process, either toluene or xylene could be used.

The tank will be under 1.5 PSIG from a nitrogen source during the cleaning procedure. The vent is a 2" line. They've provided 158*F as the temp of the vapor, and they have water from a cooling tower for the other side of the heat exchanger. I'm assuming 85*F inlet water to the HX. This will be a small, intermittent cooling load, and the outlet water will mix with a far greater flow of cooling water heading back to the towers from other equipment, so the outlet water temp from this HX isn't critical.

I do mostly steam & compressed air work, so if anyone has any guidence they can offer for condensing these process fluids, I'd really appreciate it.

 

[butelja]

If you can get your hands on a copy of Standards of Tubular Exchanger Manufacturers Association, it has tables and charts in the "Physical Properties of Fluids" section that cover nearly all common hydrocarbons, including toluene and xylene.

You will need to calculated the condensing curve (mixture composition and heat removed vs. temperature) for the stream, which is normally done using 10 points between the entrance and exit conditions. The condensing curve determines the temperature profile across the exchanger. Thermal design software such as BJAC or ChemCAD will allow you to input the condensing curve.

Hopefully you can find a copy of this reference at a library. Alternatively, you can purchase a copy for $250 from

http://www.tema.org/Order.htm

 

[Shmulik]

Sir,
Prior to calculating the condensing curve you have to complete / define the following essential parameters:
1.Total fluid quantity at the inlet of the condenser.
2.Quantity of process fluids.
3.Noncondensable quantity – nitrogen, air leaks, etc.
Please note that due to presence of noncondensables you will not be able to condense the entire amount of the process material (toluene / xylene).

 

[KernOily]

TBP, there are two ways to do this: (1) by hand, using a typical 1st law, phase equlibriium, and heat-and-mass balance analysis (2) use a process simulator like HYSYS or PRO-II. The simulator will be FAR faster because it generates its own physical and thermo/transport properties for use in the heat and mass balance calcs. If you do it by hand you'll need those properties. They are available from several sources (like butleja suggested). Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com