An Electronic Analog Computer for Solving the Flash Vaporization Equilibrium Equation
- F.W. Bubb (Washington University) | R.G. Nisle (Phillips Petroleum Co.) | P.G. Carpenter (Phillips Petroleum Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- May 1950
- Document Type
- Journal Paper
- 143 - 148
- 1950. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 4.9 Facilities Operations, 5.7 Reserves Evaluation, 4.1.2 Separation and Treating, 5.2 Reservoir Fluid Dynamics, 4.1.4 Gas Processing, 7.2.2 Risk Management Systems, 4.1.5 Processing Equipment, 4.6 Natural Gas, 4.3.4 Scale
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It is the purpose of this paper to describe an electrical computer which hasbeen constructed to solve the equations for vapor-liquid equilibrium inmulti-component systems. The instrument consists of seven component-computingunits each with proper indicating means and power supplies. Each unit is aresistance network with a voltage matching servomechanism, and each provides anoutput voltage proportional to the mol-fractions for vapor and liquid phases.These voltages are summed and matched with a reference voltage to provide thesolutions. Any reasonable number of such units may be put together to make acomputer. The theory and operation of the computer is discussed. A number ofapplications and examples of computer results are given. The computer yieldsthe over-all vapor or liquid fraction to a probable error of 0.002. Aninterpolation method is described which reduces the probable error to0.0002.
The process known as Flash Vaporization may be described as follows: A mixtureof known composition of relatively volatile components is allowed to come tothermodynamic equilibrium at some given temperature and pressure by any pathwhatsoever. In general, a vapor and a liquid phase will be present atequilibrium. The problem is to determine the fractions of the mixture in thevapor and liquid phases, and to determine the mol fractions of the variouscomponents in each phase. The relations that exist between these variousquantities at equilibrium are well known and will be given later. Theseequations are difficult to solve, yielding only to trial-and-errormethods.
The virtues of the analog computer are its speed and the automatic character ofits calculations. The device is operated by turning a crank which varies thevalue of v, the total vapor fraction. This actuates a number of servomechanismswhich perform automatically all computations.
This computer facilitates the solution of such problems as (to mention a few):Analysis of separator operation, studies of changes in composition of reservoirfluids with pressure decline, and analysis of natural gasoline plant operation.Examples of some of these problems are given in detail later.
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