Mole balances adiabatic

In Fig. 13-25, ifPg and the feed-stream conditions (i.e., F, Zi, T, Pi) are known, then the calculation of T9, V, L, yi, and Xi is referred to as an adiabatic flash. In addition to Eqs. (13-12) to (13-14) and the total mole balance, the following energy balance around both the valve and the flash drum combined must be included ... 

This equation relates temperature and conversion through the mole balance, 6. The energy balance for this adiabatic reaction in which there is negligible energy input provided by the stirrer is... 

From these three case.s. (I) adiabatic PFR and CSTR, (2) PFR and PBR with heat effects, and (3) CSTR with heat effects, one can see how one couples the energy balances and mole balances. In principle, one could simply use Table 8-1 to apply to different reactors and reaction systems w ithout further discussion, However, understanding the derivation of the.se equations w ill greatly facilitate their proper application and evaluation to various reactors and reaction systems. Ctmsequenily, the following Sections 8.2. 8.3, 8,4. 8.6, and 8,8 will derive the equations given in Table 8-1. 

Let s calculate the adiabatic CSTR volume necessary to achieve 40% conversion. Do you think the CSTR will be larger or smaller than the PFR The mole balance is... 

The mole balance, rate law. and stoichiometry are the same as in the adiabatic case previously discussed in Example 8-3 that is. 

Consider the case of adiabatic operation with one chemical reaction. A mole balance fra the limiting reactant, A, can be written as ... 

A step-limited Newton-Raphson iteration, applied to the Rachford-Rice objective function, is used to solve for A, the vapor to feed mole ratio, for an isothermal flash. For an adiabatic flash, an enthalpy balance is included in a two-dimensional Newton-Raphson iteration to yield both A and T. Details are given in Chapter 7. 

Calculate the ignition delays of a dilute H2/02 mixture in Ar as a function of initial mixture temperature at a pressure of 5 atm for a constant pressure adiabatic system. The initial mixture consists of H2 with a mole fraction of 0.01 and 02 with a mole fraction of 0.005. The balance of the mixture is argon. Make a plot of temperature versus time for a mixture initially at 1100K and... 

Since the maximum attainable temperature is sought, we assume complete adiabatic (Q = 0) combustion. With the additional assumptions that the kinetic- and potential-energy changes are negligible and that there is no shaft work, the overall energy balance for the process reduces to AH = 0. For purposes of calculation of the final temperature, any convenient path between the initial and final states may be used. The path chosen is indicated in the diagram. With one mole of methane burned as the basis for all calculations,... 

A series of trials with different assumed values of pco2/Poo and pH2o were made until a balance was obtained, the final trial showing the equilibrium composition at 3250°K. is recorded in Table IV. In this case, the 4 moles of reactants yielded 5.51 moles of products, and Qr = AH = 117.6 kcal. Therefore, the adiabatic flame temperature of the C2H4 4- 3 O2 reaction is 3250°K. (2977 10°C.). 

Use the heat of solution data in Table B.IO and solution heat capacity data to (a) calculate the enthalpy of a hydrochloric acid, sulfuric acid, or sodium hydroxide solution of a known composition (solute mole fraction) relative to the pure solute and water at 25 C (b) calculate the required rate of heat transfer to or from a process in which an aqueous solution of HCl, H2SO4, or NaOH is formed, diluted, or combined with another solution of the same species and (c) calculate the final temperature if an aqueous solution of HCl, H2SO4, or NaOH is formed, diluted, or combined with another solution of the same species adiabatically. Perform material and energy balance calculations for a process that involves solutions for which enthalpy-concentration charts are available. 

An adiabatic membrane separation unit is used to dry (remove water vapor from) a gas mixture containing 10.0 mole% H20(v), 10.0 mole% CO, and the balance CO2. The gas enters the unit at 30 C and flows past a semipermeable membrane. Water vapor permeates through the membrane into an air stream. The dried gas leaves the separator at 30°C containing 2.0 mole% H20(v) and the balance CO and CO2. Air enters the separator at 50 C with an absolute humidity of 0.002 kg H20/kg dry air and leaves at 48 C. Negligible quantities of CO, CO2, O2, and N2 permeate through the membrane. All gas streams are at approximately 1 atm. 

In this section we apply the general energy balance [Equation (8-22)] to the CSTR and to the tubular reactor operated at steady state. We then present example problems showing how the mole and energy balances are combined to size reactors operating adiabatically. 

Provided that there is a change in the number of moles upon reaction, an obvious measure of the extent of a reaction is given by the change in pressure. The latter has to be related to the stoichiometry of the reaction by quantitative analysis of the products and reactant or reactants and by material balance. Abnormal pressure effects sometimes occur due to adiabatic reactions, unimolecular reactions which are in their pressure-dependent regions (particularly in flow systems)... 

Prepare a Fortran program that will use the input number of atoms of C, H, and O in the fuel, the reactant moles and temperatures, and product composition and temperature, to make both material and energy balances for a combustion process. Assume that the process is adiabatic. Take the heat capacity equations and AH/ data from Appendix K and Table D.l. 

Consider an adiabatic tubular reactor (Davis, 1984)[15] with the following data length L = 2 m, radius Rp = 0.1 m, inlet reactant concentration cO = 30 moles/m3, inlet temperature TO = 700K, enthalpy AH = -10000 J/mole, specific heat capacity Cp = 1000 J/kg/K, activation energy Ea = 100 J/mole, p = 1200 kg/m3, velocity uO = 3 m/s, and rate constant kO = 5 s-1. Dimensionless concentration (y) and dimensionless temperature (9) are governed by material and energy balances as ... 

If desired, (12-79) through (12-90) can be applied with mass units rather than mole units. No enthalpy balance equations are required because ordinarily temperature changes in an adiabatic extractor are not great unless the feed and solvent enter at appreciably different temperatures or the heat of mixing is large. Unfortunately, the group method is not always reliable for liquid-liquid extrac-... 

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