Document Type

Thesis

Date of Award

5-31-1983

Degree Name

Master of Science in Management Engineering - (M.S.)

Department

Industrial and Management Engineering

First Advisor

Carl Wolf

Abstract

In order to minimize total costs (investment plus operating costs) when elevating process equipment to meet hydraulic requirements, it is essential to establish cost effective and energy efficient pump suction systems. During the early stages of design of such systems it is most critical that preliminary costs be determined in a timely manner to avoid job delays. One method of accomplishing this is through the use of a cost estimating relationship for defining the price behavior of alternative pump suction systems. This thesis describes the procedure used to develop a mathematical model to predict the cost of elevating vertical drums. This model may be used to perform overall economic evaluations as a function of the specified payout period before definitive designs have been firmly established.

Using a multiple regression correlation technique, several mathematical relationships were investigated to determine the economic consequences of elevating vertical drums. An empirical model describing the incremental costs as a function of skirt heights was represented by a family of parabolic curves displaced by a 3rd order polynomial function of the diameter. The procedure for developing the model and the statistical theory in relationship to the multiple regression programs are discussed. A hand calculation procedure simulating all of the program operations is included to demonstrate the tedious computations which are easily and quickly solved by computer. The model was applied to three typical examples requiring tradeoff studies to evaluate various combinations of vessel elevations, pump efficiencies and NPSH requirements.

Use of the mathematical model determined in this thesis, which is superior to selection methods presently available, will consistently allow an engineer to quickly and accurately pick an adequate pump suction system arrangement. Because of the magnitude of possible savings through the use of the model, the cost of development may be recovered very quickly. Past subjective decisions may be replaced by an objective procedure, allowing consistency in the decision making process regardless of the individual conducting the economic evaluation.

It is recommended that the mathematical model developed be tested further before being released as a general procedure to be followed by contractors in production work. In addition, other similar models should be developed to evaluate suction vessel arrangements for horizontal drums and towers.

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