3 replies to this topic

[mwkuppe]

Hello all,

I'm a ChE senior working on my design project and we have been given CAPCOST to aid in the economic analysis of the project. I am wondering if anyone knows a resource that explains (even briefly) what parameters CAPCOST uses in calculating the equipment cost.

For example, the project involves the use of long tube evaporators to remove water from ethylene glycol (I can provide operating conditions if necessary). The CAPCOST inputs for evaporators consist only of MOC, Operating Pressure, and Heat Transfer Area. Does capcost assume a general size for a given heat transfer area? Does it take fluid residence time in the evaporator into consideration? I'm capable of calculating these additional pieces of information with methods from Douglas and Perry's. But because we were told to use CAPCOST, I feel it would be beneficial to have a base understanding of where the costs come from rather than just assume the numbers that it gives are accurate.

I've searched various websites regarding these questions and only get instructions on how to use the program. Any guidance provided would be very much appreciated. Thank you.

[Fr3dd]

Hello mwkuppe,

CAPCOST is a software that was originally included in a cd with the book "Analysis, synthesis, and design of chemical processes" of Richard Turton, Richard C. Bailie, Wallace B. Whiting. I can remember that the considerations and equations used for the equipment cost calculation performed by this software were fully describes in a specific chapter of the book.

If you have access to the software I'm almost sure you can also have access to the book. If you don't, you can find it here . It's also nice If you have access to older projects in your company or to more than one cost estimation method so you can compare your results and apply your engineering judgement to reach an accurate estimation. Also, remember to apply a correction factor (inflation) to the results, I'm not sure if the factors considered by the softwares are up to date.

Regards,

[markymaark]

The majority costs for a heat exchanger are the physical materials themselves. There's little to no engineering done anymore as these are fairly standard unitops.

Therefore, CAPCOST is basically asking HOW MUCH metal will be needed. So it asks area, and then pressure (for design thickness). Lastly, MOC is a big cost. You should check http://www.coleparmer.com/ for pipe compatibility (if your liquid corrodes your MOC).

This type of estimate would get you anywhere to 20-50% of the actual cost. And hey, that's engineering. The only way to get a closer estimate would be to contact a vendor with a specification, which as a student they would not do.

[mwkuppe]

Thank you both for your responses. Both resources proved to be very helpful.