A chemical engineer is considering two sizes of pipes for moving distillate from a refinery to the tank farm. A small pipeline will cost less to pur­chase (including valves and other appurtenances), but will have a high head loss and, therefore, a higher pumping cost. The small pipeline will cost $1.7 million installed and have an operating cost of $12,000 per month. A larger-diameter pipeline will cost $2.1 million installed, but its operating cost will be only $8000 per month. Which pipe size is more economical at an interest rate of 1% per month on the basis of an annual worth analysis? Assume the salvage value is 10% of the first cost for each pipeline at the end of the 10-year project.

Question

What will be an ideal response?

Answer 1

AWsmall = -1,700,000(A/P,1%,120) – 12,000 + 170,000(A/F,1%,120)
= -1,700,000(0.01435) – 12,000 + 170,000(0.00435)
= $-35,656

AWlarge = -2,100,000(A/P,1%,120) – 8,000 + 210,000(A/F,1%,120)
= -2,100,000(0.01435) – 8,000 + 210,000(0.00435)
= $-37,222

Select small pipeline