Revised Absorption Column Costing

The costing for this unit has been revised from that presented in 

Section 6.5 because of the detailed design information now available. The costing was done in accordance with the recommendations of Mu let, Corripio and Evans (Ref. Al 3). Their method utilizes correlations for the cost of a simple carbon-steel structure. Factors are then applied to account for the cost of other materials, the inclusion of trays, for operating pressure, and for incidentals such as ladders and railings. The cooling circuit was costed on the basis of heat-transfer area using similar correlations. Details of the cost estimation calculations are included in Appendix G.5. 

The final cost estimate for this absorption column and associated structures was determined to be As870 000. This is significantly more than the first estimate (As250 000), however, the new cost reflects the need for a larger column than originally considered. 

The absorption column design represents a compromise between mass transfer factors and economic considerations. The final design specification is for a column of 1.8 m diameter, approximately 32 m high, and containing 59 sieve trays. 

Weak-acid condensate is fed to tray number 13, and make-up water is directed to the top tray (number 59). 

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