Plants are designed for some maximum nameplate capacity but commonly produce less. The operating cost per kilogram of feed can be found by dividing Eq. (11-2) by the feed rate.
The kg steam/h, kg water/h, and kW elec/h are all directly proportional to F. Thus, except for labor costs, the operating cost per kilogram will be constant regardless of the feed rate. Since labor costs are often a small fraction of total costs in automated continuous chemical plants, we can treat the operating cost per kilogram as constant.
Capital cost per kilogram depends on the total amount of feed processed per year. ...