Page 51 - Chemical process engineering design and economics

Production and Capital Cost Estimation 37

Table 2.2 Sources of Chemical Raw-Material Prices____________

Aldrich Chemical Catalog, Aldrich Chemical Co., Milwaukee, Wl.
Alfa Inorganic Ltd., Beverly, MA.
The Chemical Marketing Reporter, New York, NY.
Fisher Chemical Index, Fisher Scientific Co., New York, NY.

Water, which is an increasingly important utility, is used both as a coolant
and a process fluid. Its cost, as shown in Table 2.3, depends on the source or
grade. Cooling water is obtained from reservoirs, rivers, and lakes and in many
cases a cooling tower will recool the water. Process water quality depends on the
needs of the process and may be city water, filtered, softened, demineralized cool-
ing-tower water, condensate, distilled, and boiler feed water. The lowest grade of
water is obtained from a well or river, which is filtered to remove suspended sol-
ids. The electronics industry needs an even purer grade called ultrapure water.
Processing raw water to improve its grade increases its cost. A local water supplier
or the Water Works Association can give the cost of city water.
Compressed air is mainly used to operate pneumatic instruments and control
valves. Air is also used in aerobic fermentations for the production of chemicals
and drugs and in biological waste treatment.
Refrigeration is needed when the required temperature is below the cooling-
water temperature, such as in the production of liquid nitrogen and oxygen. Re-
frigeration is also used when the material being processed is sensitive to high tem-
peratures, such as in food and pharmaceutical processes.
Fuel costs have a major impact on utility costs and will have an even greater
impact in the future. When the price of oil rose in the 1970s, the chemical industry
responded by increasing their efforts to improve the energy efficiency of their
processes. Presently, the price of oil is low, but in the future the price of oil will
rise again. Also, the consumption of oil and other fuels have an adverse effect on
the environment so that efforts to conserve energy will continue.
Labor

Chemical plants require several types of labor. There is direct labor, consisting of
operating labor to produce a chemical, and maintenance labor to maintain the
process. There is also indirect labor, needed to operate and maintain facilities and
services. Happel and Jordan [6] have pointed out that the contribution of labor
costs to the product cost is small. But labor cost contributes to the cost of several
other items, as shown in Table 2.1. When developing a new process, we can esti-
mate the number of operators by visualizing the operations for the various

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