Page 182 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

pumps, compressors and turbines, columns and vessels, fired heaters, and exchangers. Each piece of
equipment is roughly sized and the approximate cost determined. The total cost of equipment is then
factored to give the estimated capital cost.

Diagrams: Based on PFD as described in Chapter 1. Costs from generalized charts.

Note: Most individual student designs are in this category.

Preliminary Design (also known as Scope) Estimate

Data: This type of estimate requires more accurate sizing of equipment than used in the study estimate. In
addition, approximate layout of equipment is made along with estimates of piping, instrumentation, and
electrical requirements. Utilities are estimated.

Diagrams: Based on PFD as described in Chapter 1. Includes vessel sketches for major equipment,
preliminary plot plan, and elevation diagram.

Note: Most large student group designs are in this category.

Definitive (also known as Project Control) Estimate

Data: This type of estimate requires preliminary specifications for all the equipment, utilities,
instrumentation, electrical, and off-sites.

Diagrams: Final PFD, vessel sketches, plot plan, and elevation diagrams, utility balances, and a
preliminary P&ID.

Detailed (also known as Firm or Contractor’s) Estimate

Data: This type of estimate requires complete engineering of the process and all related off-sites and
utilities. Vendor quotes for all expensive items will have been obtained. At the end of a detailed estimate,
the plant is ready to go to the construction stage.

Diagrams: Final PFD and P&ID, vessel sketches, utility balances, plot plan and elevation diagrams, and
piping isometrics. All diagrams are required to complete the construction of the plant if it is built.

The five classifications given in Table 7.1 roughly correspond to the five classes of estimate defined in
the AACE Recommended Practice No. 17R-97 [4]. The accuracy range and the approximate cost for
performing each class of estimate are given in Table 7.2.

Table 7.2 Classification of Cost Estimates