If you are seriously into using monte calo type simulations for this type of thing consider @Risk which is a Monte Carlo add in for Excel. I have used it for other types of simulation but it can be used for the type of problem you describe.
My company is currently looking to upgrade / replace our existing (1970)Girdler design H2S production plant (Require approx 8 tpd capacity). We are looking for potential technology providers and would also like to do some benchmarking of more recently installed plants to establish best practice...