Given the models, various reactor analyses can be performed. That corresponds to a residence time of to 3678 seconds, more than 6 times that of the RPLUG residence time. The study shows a reactor liquid volume of 20.6 m 3 is required to achieve 70% C4H10 conversion. C4H10 content drops from 90 mol % to 33.7 mol % (62.5% conversion) with this initial volume of 3 m 3.Ī DESIGN-SPEC block is set up to find the reactor volume required for 70% C4H10 conversion. To start the simulation, initial value of 3 m 3 is assumed for the CSTR reactor volume. Profiles for the molar compositions of C4H10 and IC4H10 and the PFR reactor temperature are given below.Īspen RCSTR reactor model is used with heat duty set to 0 (i.e., adiabatic) and reaction model ISOMER. 70% of C4H10 conversion is achieved with reactor length of 410 meter, or 603 second of residence time.
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It is found that the conversion of C4H10 reaches a maximum of about 72%. To start the simulation, initial values of 0.1 meter in diameter and 1000 meter in length are assumed. Aspen requires input of reactor dimensions in lieu of reactor volume. They are used to construct processes with proper feed streams and reactor conditions.Īspen RPLUG reactor model is used with reactor type Adiabatic Reactor and reaction model ISOMER. Therefore, the above equation can be rewritten as follows.įrom k' and K eq, we can derive at the rate constant for the reverse reaction, k".Īspen model library provides RPLUG (PFR) reactor model and RCSTR (CSTR) reactor model. The above equation gives K eq=2.51 at 360 K. It is also known that the heat of reaction is -6900 J/mol of n-butane and the chemical equilibrium constant is 3.03 at 60☌.
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The reactant concentration is given in terms of molarity (kmol/m 3). The forward reaction specific rate is 31.1 h -1 (0.008639 sec -1) at 360 K with activation energy of 65.7 kJ/mol (65.7x10 6 J/kmol). The reaction stoichiometry is shown below:īoth forward and reverse reactions are 1st order with respect to reactants. To describe the n-butane isomerization reaction, an Aspen reaction model of POWERLAW type is created: ISOMER. PENG-ROB predicts the heat of isomerization to vary from -7430 J/mol C4H10 at 330 K to -7080 J/mol C4H10 at 360 K. The isomerization heat of reaction is also a function of temperature. Pressure also affects liquid heat capacity. The higher the temperature, the higher the heat capacity will be. Within the temperature range of 330 K to 360 K, PENG-ROB predicts liquid heat capacity of 157-185 J/mol One of several equations-of-state well-known to be suitable for hydrocarbon systems, Peng-Robinson equation-of-state should provide reasonable calculations for heats of reaction and heat capacities. PENG-ROB, Aspen Peng-Robinson equation-of-state property model, is chosen to describe the thermophysical properties of this hydrocarbon liquid mixture. These three components are called directly from built-in Aspen pure component databanks.ĭifferent property models can yield different predictions for various thermophysical properties used in mass and energy balance calculations. The liquid catalyst is not included because its flowrate is not known and the specific reaction rate has been given for the reaction condition. Three components are considered in the Aspen model: C4H10 (n-butane), IC4H10 (isobutane) and IPENTANE (2-methyl-butane). Calculate the CSTR volume for the same conditions as the PFR.Plot and analyze X, X e, T and -r A down the length of the reactor.Calculate the PFR volume necessary to process 100,000 gal/day (160 kmol/h) at 70% conversion of a mixture 90 mol % n-butane and 10 mol % of i-pentane, which is considered an inert.
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This elementary reversible reaction is to be carried out adiabatically in the liquid phase under high pressure using a liquid catalyst which gives a specific reaction rate of 31.1 h -1 at 360 K. Normal butane, C 4H 10, is to be isomerized to isobutane in a plug-flow reactor. Example 11-3 Adiabatic Liquid-Phase Isomerization of Normal Butane
#Aspen plus v11.1 download download
You can download the ASPEN backup file here that completes this problem. This section is a tutorial to walk you through Problem 11-3 for the 1st edition of Essentials of Chemical Reaction Engineering. Aspen Plus - Examples ASPEN PLUS™ Example Problems