Mole balances with heat effects

We call Equation (2-6) the dit ferential form of the design equation for batch reactor because we have written the mole balance in terms of converstor The difTereniial forms of the batch reactor mole balances. Equations (2-5) ani (2-6). are often used in the interpretation of reaction rate data (Chapter 5) atu for reactors with heat effects (Chapter 9), respectively. Batch reactors are fre qiiently used in industry for both gas-phase and liquid-phase reactions. Thi laboratory bomb calorimeter reactor is widely used for obtaining reaction raa data (see Section 9.3). Liquid-phase reactions are frequently carried out it batch reactors when small-scale production is desired or operating diflicultie rule out the use of continuous (low. systems. 

Examples on How to Ese Table 8-1. Wc now couple the energy balance equations in Table 8-1 with the appropriate reactor mole balance, rate law. stoichiometry algorithm to solve reaction engineering problems with heat effects. For example, recall rate law for a first-order reaction. Equation (E8-1.5) in Example 8-1. 

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. 

In contrast to the processes we encountered previously, which were largely or entirely isothermal in nature, distillation has substantial heat effects associated with it. Consequently, we expect heat balances to be involved in modeling the process, as well as the usual mass balances and equilibrium relations. These balances are formulated entirely in molar xmits because the underlying equilibrium relations, such as Raoult s law and its extension, or the separation factor a, are all described in terms of mole fractions. Thus, the flow rates L and G, which appear in Figure 7.16, are both in rmits of mol/s, enthalpies H in units of J/mol, and the liquid and vapor compositions are expressed as mole fractions x and y of a binary system. 

Note Use ratio units. If careful with units, the liquid units can be in mass and the gas units in moles, which is effectively the form of the equilibrium data. Derive the operating equation and external mass balances to determine where to include the molecular wei t of HCl (36.46). Because HCl has a very large heat of absorption in water, the column will have to be well-cooled to maintain the temperature at 10°C. Commercial units are not isothermal. 

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