Evaluation of preliminary industrial design work . Purchase cost of miscellaneous equipment. Total purchase cost of major equipment items .

1. Summary of
Production Costs
Dr. K. Shahzad Baig
Memorial University of Newfoundland (MUN) Canada

5. Preliminary design work has been done on a process to recover a valuable product from an
effluent gas stream. The gas will be scrubbed with a solvent in a packed column; the
recovered product and solvent separated by distillation; and the solvent cooled and recycled.
The major items of equipment that will be required are detailed below.
1. Absorption column: diameter 1 m, vessel overall height 15 m, packed height 12 m, packing
25 mm ceramic intalox saddles, vessel carbon steel, operating pressure 5 bar.
2. Recovery column: diameter 1 m, vessel overall height 20 m, 35 sieve plates, vessel and
plates stainless steel, operating pressure 1 bar.
3. Reboiler: forced convection type, fixed tube sheets, area 18.6 m2, carbon steel shell,
stainless-steel tubes, operating pressure 1 bar.
Problem statement

6. 4. Condenser: fixed tube sheets, area 25.3 m2, carbon steel shell and tubes, operating
pressure 1 bar.
5. Recycle solvent cooler: U-tubes, area 10.1 m2, carbon steel shell and tubes, operating
pressure 5 bar.
6. Solvent and product storage tanks: cone roof, capacity 35 m3, carbon steel. Estimated
service requirements:
Steam 200 kg/h, Cooling water 5000 kg/h, Electrical power 100 kWh/d (360 MJ/d)
Estimated solvent loss 10 kg/d; price £400/t. Plant attainment 95 per cent.
Estimate the capital investment required for this project, and the annual operating
cost; date mid-2004

7. Solution
Absorption column:
diameter 1 m, vessel overall height 15 m, packed height 12 m, packing 25 mm ceramic
intalox saddles, vessel carbon steel, operating pressure 5 bar. Bare vessel cost (Figure 6.5a)
£ 21,000; material factor 1.0, pressure factor 1.1
Packing cost (Table 6.3) £840/m3

8. Recovery column:
Diameter 1 m, vessel overall height 20 m, 35 sieve plates, vessel and plates stainless steel,
operating pressure 1 bar.
Bare vessel cost (Figure 6.5a): £26,000; material factor 2.0, pressure factor 1.0
Cost of a plate from figure 6.7a : 200

9. Reboiler
Forced convection type, fixed tube sheets, area 18.6 m2, carbon steel shell, stainless-
steel tubes, operating pressure 1 bar.
Bare cost (Figure 6.3a) £11,000; type factor 0.8, pressure factor 1.0
Condenser
Fixed tube sheets, area 25.3 m2, carbon steel shell and tubes, operating pressure 1 bar.
Bare cost (Figure 6.3a) £8500; type factor 0.8, pressure factor 1.0

10. Recycle solvent cooler
U-tubes, area 10.1 m2, carbon steel shell and tubes, operating pressure 5 bar.
Bare cost (Figure 6.3a) £4300; type factor 0.85, pressure factor 1.0
Solvent storage tank
Cone roof, capacity 35 m3, carbon steel. Purchase cost (Table 6.2)
Product storage tank
Cone roof, capacity 35 m3, carbon steel.

11. Purchase cost of miscellaneous equipment

12. Total purchase cost of major equipment items (PCE)

13. Following books were used in preparation of notes
 Blank, L., Tarquin. A. 2005. Engineering Economy. 6th Edition, McGraw-Hill.
 Eschenbach, T. G. 2003. Engineering Economy”, 2nd Edition, Oxford University Press
 Riggs, J. L., Bedworth, D. D., Randhawa, S. U. 1996. Engineering Economics”, 4th Edition, Tata McGraw-Hill.
 Riggs, J. L., West. T. M. 1986. Essentials of Engineering Economics”, 2nd Edition, McGraw-Hill.
 Peter, M. S., Timmerhaus, K. D. 1991. Plant Design and Economics for Chemical Engineers. 4th Edition, McGraw-Hill.