Page 195 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

= ($23,000,000)(1.359)(1.397) = $43,644,000

In most situations, cost information will not be available for the same process configuration; therefore,
other estimating techniques must be used.

7.3.1 Lang Factor Technique

A simple technique to estimate the capital cost of a chemical plant is the Lang Factor method, due to Lang
[6, 7, 8]. The cost determined from the Lang Factor represents the cost to build a major expansion to an
existing chemical plant. The total cost is determined by multiplying the total purchased cost for all the
major items of equipment by a constant. The major items of equipment are those shown in the process
flow diagram. The constant multiplier is called the Lang Factor. Values for Lang Factors, F , are given
Lang
in Table 7.7.

Talbe 7.7 Lang Factors for the Estimation of Capital Cost for Chemical Plant (from References [6,
7, 8])

The capital cost calculation is determined using Equation 7.5.

(7.5)

where C TM is the capital cost (total module) of the plant

C p,i is the purchased cost for the major equipment units

n is the total number of individual units

F Lang is the Lang Factor (from Table 7.7)

Plants processing only fluids have the largest Lang Factor, 4.74, and plants processing only solids have a
factor of 3.10. Combination fluid-solid systems fall between these two values. The greater the Lang
Factor, the less the purchased costs contribute to the plant costs. For all cases, the purchased cost of the
equipment is less than one-third of the capital cost of the plant. The use of the Lang Factor is illustrated in