The utilities consumed by all process units in the simulation are automatically computed and reported in the output. The consumption and production of the utilities is defined in the submodels of each process unit. Utilities are not listed in the input file but do require that the user provide the necessary prices. For calculation purposes, the capital investment required for a process is treated as a utility.
The units of measure used must be consistent for all submodels and user-entered price data. For example, if ‘million US dollar’ is the adopted unit of measure, all submodels must reflect correlations based on the same.
The unit of measure used in the simulations is GASLHV, which represents the total heat content of the utility (and is not mass specific). For submodels, the more convenient units or measure are FUEL for MMBtu of liquid fuels and GASLHV for MMBtu of gas fuels.
A list of the different types of utilities is presented. The short identification (ID) is the designated term used in submodels.
ID Component
FUEL Fuel
HPS High Pressure Steam
MPS Medium Pressure Steam
LPS Low Pressure Steam
BFW Boiler Feed Water
CW Cooling Water
POWER Power
CHEM Chemicals
CAPITAL Capital Cost
GASLHV Fuel Gas (BTU, kCal, GJ)
UT1 User-defined utility process unit submodels
UT2 User-defined utility