Zevnik-Buchanan method

Figure 9-2 Temperature factor curve used in the Zevnik-Buchanan method.

For these three plants cost calculations are performed based on the functional unit method. This method was developed by DSM research, and it is an updated version of the Zevnik-Buchanan method as developed by DuPont. 

Typical methods are those of F. C. Zevnik and R. L. Buchanan [Chem. Eng. Progi , 59, 70-77 (Feb. 1963)] and J. H. Taylor Eng. 6-Proc. Econ., 2, 259-267, 1977). The former is mainly a graphical method of estimating the cost per functional unit (Cp) based on the capacity, the maximum pressure, the maximum temperature, and the materials of construction. The Taylor method requires the determination of the costliness index, which is dependent on the complexity of the process. A simpler method was suggested by S. R. Timms (M.Phil. thesis, Aston University, England, 1980) to give the battery hmits cost for gas phase processes only in U.S. dollars with a Marshall and Swift index of 1000. The simple equation is... 

Estimate the cost of a 30,000 metric ton/yr isopropanol plant, based on the process given in Figure 9-5 in 1971. Use the method of Zevnik and Buchanan. The highest pressure is 4,260 psia and the maximum temperature is 554°F. It will be assumed that carbon steel can be used. 

Step-counting methods are based upon a number of processing steps or functional units. The concept was first introduced by H. E. Wessel, Chem. Eng., 1952, p. 209. Subsequently, R. D. Hill, Petrol. Refln., 35(8) 106-110, August 1956 P C. Zevnik and R. L. Buchanan, Chem. Eng. Progress, 59 2) 70-77, Pebruary 1963 and J. H. Taylor, Eng. Process Econ., 2 259-267, 1977, further developed the stepcounting method. 

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