Page 49 - Plant design and economics for chemical engineers

32 PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS

TABLE 2
Estimated purchased-equipment cost for alkylation unit?

Designation Item Purchased cost
T-l Storage tank $ 21,800
T-2 Storage tank 36,700
T-3 Holding tank 16,200
P-l Centrifugal pump (with motor) 1,500
P-2 Centrifugal pump (with motor) 1,700
P-3 Centrifugal pump (with motor) 1,600
P-4 Positive-displacement pump 6,200
R-l Jacketed (stirred) reactor 33,400
$144,100
tJanuary 1, 1990 costs. See Fig. 2-5.

TABLE 3
Summary of purchased-equipment
cost for complete process unit

Process unit Purchased cost
Alkylation $ 144,100
Fractionators 175,800
Sulfonation 245,100
Neutralization 163,700
Spray dryer 393,500
Auxiliary units 142,800
Total $1,165,000

Table 3 and is the basis for the estimated fixed-capital cost tabulation given in
Table 4. The probable error in this method of estimating the fixed-capital
investment is as much as +30 percent.
An evaluation of the operating labor and utilities requirements of the
process must be made before the total product cost can be estimated. Details
for evaluating these direct production costs are given in Chap. 6 and Appendix
B. The estimate of the total product cost for the manufacture of 15 million lb
per year detergent, based on methods outlined in Chap. 6, is presented in
Table 5.
Once the total product cost has been estimated, the design group is in a
position to evaluate for management the attractiveness of the proposed process
using such measures of profitability as rate of return, payout time, or present
worth. These methods are fully outlined in Chap. 10. The design report, as
mentioned previously, completes the preliminary design. ,