Page 229 - Plant design and economics for chemical engineers

200 PLANT DESIGN AND ECONOMICS FOR CHEMlCAL ENGINEERS

TABLE 23
Cost tabulation for selected utilities and labofi$
1989 costs based on U.S. Gulf Coast location
cost

Steam costs
Exhaust, $/lOOO lb 1.10
Pressure of 100 psig, $/lOOO lb 2.40
Pressure of 500 psig, $/lOOO lb 3.60
Fuel costs
Gas at well head including gathering-system costs:
Existing contracts, $/mi\\ion Btu 2.40
New contracts, $/million Btu 3.00
Fuel oil in $/million Btu with 6.25 million Btu/bbl 3.00
Gas transmission costs in g/l00 miles 7.30
Plant fuel gas in $/million Btu 3.20
Purchased power for ntidcontinent USA in $/kWh 7.00
Water costs
Process water (treated) in e/l000 gal 80
Cooling water in r/l000 gal (tower or river) 10
Labor rates
Supervisor, $/h 28.00
Operators, S/h 21.00
Helpers, $/h 17.40
Chemists, $/h 20.00
Labor burden as % of direct labors 25
Plant general overhead as % of total labor + burden 40
t Based on information updated from C. C. Johnnie and D. K. Aggarwal,
Calculating Plant Utility Costs, Chem. Emg. Progr., 73(11):84 (1977) and
M. Kiley, “National Construction Estimator,” 37th ed., Craftsman Book
Company of America, Carlsbad, CA, 1989.
$ See Appendix B for a more detailed listing of utility and related costs.
B Labor burden refers to costs the company must pay associated with and
above the base labor rate, such as for Social Security, insurance, and other
benefits.

sheets.ll In this method, a process step is defined as any unit operation, unit
process, or combination thereof, which takes place in one or more units of
integrated equipment on a repetitive cycle or continuously, e.g., reaction,
distillation, evaporation, drying, filtration, etc. Once the plant capacity is fixed,
the number of employee-hours per ton of product per step is obtained from Fig.
6-8 and multiplied by the number of process steps to give the total employee-
hours per ton of production. Variations in labor requirements from highly
automated processing steps to batch operations are provided by selection of the
appropriate curve on Fig. 6-8.

llMethod originally proposed by H. E. Wessel, New Graph Correlates Operating Labor for
Chemical Processes, Chem. Eng., 59(7):209 (July, 1952).