Page 122 - Plant design and economics for chemical engineers

98 PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS

FIGURE 3-4
Example of a graphic panel for a modern industrial plant with a computer-controlled system.
(Courtesy of C. F. Braun and Company.)

initial installation. For example, a close-coupled motor pump utilizing a high-
speed motor may require less space and lower initial cost than a standard motor
combined with a coupled pump. However, if replacement of the impeller and
shaft becomes necessary, the repair cost with a close-coupled motor pump is
much greater than with a regular coupled pump. The use of a high-speed motor
reduces the life of the impeller and shaft, particularly if corrosive liquids are
involved. If the engineer fails to consider the excessive maintenance costs that
may result, an error in recommending the cheaper and smaller unit can be
made. Similarly, a compact system of piping, valves, and equipment may have a
lower initial cost and be more convenient for the operators’ use, but mainte-
nance of the system may require costly and time-consuming dismantling opera-
tions.

UTILITIES
The primary sources of raw energy for the supply of power are found in the heat
of combustion of fuels and in elevated water supplies. Fuel-burning plants are
of greater industrial significance than hydroelectric installations because the
physical location of fuel-burning plants is not restricted. At the present time,
the most common sources of energy are oil, gas, coal, and nuclear energy. The
decreasing availability of the first two sources of energy will necessitate the use
of alternate forms of energy in the not-too-distant future.
In the chemical industries, power is supplied primarily in the form of
electrical energy. Agitators, pumps, hoists, blowers, compressors, and similar