Author: workhouse123
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Material Balances in Reacting Systems
Reacting systems are characterized by the disappearance of reactants and appearance of the products. Clearly, molecular species are not conserved in the reaction, and at steady state, the rate of input of a compound participating in the reaction is not equal to the rate of its output. However, as long as no nuclear reactions are occurring…
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Material Balances in Nonreacting Systems
Material balances in nonreacting systems are illustrated through a simple example involving dilution of a concentrated solution, an operation frequently encountered in a chemical process plant. Example 6.2.1 Dilution of a Concentrated Aqueous Solution The production process for sodium hydroxide (NaOH) yields a 28% (by mass) solution of sodium hydroxide in a membrane cell. A…
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Quantitative Principles of Material Balance
A chemical process typically consists of several units that may involve chemical reactions and/or simple physical separation and mixing operations, as described in previous chapters. The process streams may be constituted of a single phase (gas/liquid/solid) or may be multiphase in nature. A unit may or may not be operating at steady state. Regardless of the…
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Computational Tools—Machines and Software
The two components enabling the computations are the hardware—machines that perform the calculations—and the software—the instructions to run solution algorithms by the machines. Both these components are described in the sections that follow. Computational Machines A counting frame, or an abacus, is one of the earliest devices and has been used for more than three millennia…
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Basic Computational Problems
Chemical engineers encounter problems ranging in complexity from simple arithmetic calculations to highly involved ones requiring programming. The following examples present of a few of these problems along with solution techniques using Excel and Mathcad. Example 5.1 Friction Factor for Pipe Flow Calculate the Fanning friction factor using the Nikuradse equation for the flow of…
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Quantitative Analysis of Fluid Flow
As mentioned previously, one of the major responsibilities of a chemical engineer involves determination of power and energy requirements for the flow of fluids. This requires understanding the energy balance for the fluid flow, presented in section 5.2.1. 5.2.1 Energy Balance for Fluid Flow The energy balance for systems involving a simple flow of a fluid…
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Qualitative Description of Flow in Conduits
Consider a pipe closed at both ends and filled with a liquid. The liquid is composed of a very large number of molecules, each one of which occupies a certain position in the stagnant body of the liquid. The position of the molecule is not completely fixed, as it would be in the case of…
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Computational Tools—Machines and Software
The two components enabling the computations are the hardware—machines that perform the calculations—and the software—the instructions to run solution algorithms by the machines. Both these components are described in the sections that follow. 4.3.1 Computational Machines A counting frame, or an abacus, is one of the earliest devices and has been used for more than three…
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Solution Algorithms
The theoretical basis and approach to developing the solutions of various types of computational problems is briefly described in this section. This discussion is not meant to be exhaustive or comprehensive, but rather introductory, in nature. Several alternative techniques are available for solving the various types of problems; the following discussion is in most cases…
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Nature of Chemical Engineering Computational Problems
Chemical engineers deal with a multitude of equations ranging in complexity from simple linear equations to highly involved partial differential equations. The solution techniques accordingly range from simple calculations to very large computer programs. The classification of the problems based on the mathematical nature is presented in the following sections. 4.1.1 Algebraic Equations Algebraic equations…