[ecfe111]

Hi Forum

I am doing a design project, and one of the parts I am going to work on is a heatexchanger, which is heating a Hydrocarbon gas stream. Now i know that the forum has rules against doing other peoples homework, so I do not ask for a specific solution to the following question, Therefore you will notice no information is given with regards to stream composition and temperature. I would however like to know how to deduce the answer myself.



What i want to know is when to heat using Dowtherm as a utility, and when to heat using steam, assuming availability of both? The reason for me asking is that i am a bit concerned by the temperatures i need to reach in the heatexchanger, and thus I am not sure if they can be reached using steam. I guess this is partly connected to me not knowing the maximum temperature steam could be available in for practical purposes. 

Thank you for your help,
Regards

[pankajshah]

You can use the steam if the process temperature can be attained by say about 7 kg/cm2(g) pressure. For higher temperature, you will have to use Dowtherm.

Heat transfer coefficient is much better with steam than with Dowtherm.