34075786 Classes Hysys 5 Reactions and Reactors

DESIGN PROCESS HYSYS PRACTICES 1 ADRIANA ARISTIZÁBAL 7. HYSYS IN CHEMICAL REACTORS 7.1 Types of Reaction in HYSYS In Hysys there are two types of reaction models Models that do not use reaction kinetic parameters: conversion and balance. Reaction models using kinetic parame ters: Heterogeneous catalytic kinetic rat and simple. 7.1.1 Models used NO reaction kinetic parameters: With these models is not possible to design a reactor because the reaction kinet ics, reactor volume and flow pattern have no influence on the calculations. Conversion Reactions This type of reaction does not require any package for prediction. You must spec ify the stoichiometry of the reaction and the conversion can be a function of te mperature. - The conversion does not may exceed 100%. - The reaction proceeds until it reaches the specified conversi on or limit the reagent is consumed. Reactions require knowing the relationship between the equilibrium constant balance and temperature. There are different ways of relating T Keq in HYSYS for  this type of reaction: Foreign Keq vs. T: Ln (Keq) Equation: Keq is a function of temperature as follows: Gibbs Free Energy -Reactions of equilibrium (Equilibrium): Fixed Keq: if Keq or Ln (Keq) is a cons tant Keq vs. T table: If you have Keq vs. temperature data in tabular form. Balancing Reactions are applicable to reversible reactions only. This model assu mes that following a given stoichiometry, the reaction proceeds until equilibriu m is reached between the substances involved. Required to specify the reaction s toichiometry and equilibrium constant as a function of temperature. In HYSYS is a database Balancing reactions which have the relationship of Keq vs . T. NOTE The temperature of all Keq equations should ALWAYS be Kelvin, therefore the coef ficients A, B, etc should be adjusted according to this condition. If this is to o complicated to be generated Keq vs. T tables and provide the data this way. 7.1.2 Models of reaction kinetic parameters used: When taking into account the kinetics, these models allow to involve the flow pa ttern of the reactor and its geometric characteristics within the simulation, wh ich, coupled with a criterion such as the desired conversion and / or selectivit y required, enables the measurement equipment. Heterogeneous Catalytic You must specify the expression of the reaction rate as follows: The terms of heterogeneous catalytic reactions relate to the direct and reverse reactions (indicated by '), where K: reaction constant. E: activation energy A: pre-exponential factor f (Basis): the ownership of which depends on the reaction

 rate (concentration, partial pressures ...) Specify the units of the expression  of the reaction rate. Kinetics • It applies to cases where the kinetic reaction rate limited. • Can be used to characterize elementary reactions, reversible and irreversible, where the stoich iometric coefficients agree or disagree with the reaction kinetic orders. • To s pecify the required stoichiometry of reaction, reaction orders and reverse of ea ch of the substances in the reaction, and the frequency factor and activation en ergy of the constants of forward and reverse reactions. If the reaction is irrev ersible orders may be omitted • In this tab you specify the stoichiometric coefficients which are negative for  reactants and positive for products which if well specified must have a zero ba lance failure. • You must also specify the order of the reverse reaction and dir ectly to each component. • On the Basis tab you must specify the property which is based on the reaction rate, the component to which it refers is, the temperature range which is valid for the reaction rate, the • The Kinetic reactions are as follows: Simple Rat • It applies to cases where the kinetic reaction rate limited. • Can be used to characterize elementary reactions or elementary reactions, reversible or irrever sible, where the stoichiometric coefficients coincide with the reaction kinetic orders. • is required to specify the stoichiometry of reaction the frequency fac tor and activation energy of the direct reaction constant. In the case of revers ible reactions, also requires Reactions in HYSYS: Conversion Reaction Type Kinetic Equilibrium Gibbs DESCRIPTION Conversion% (x% =  C0 C1T C2T2) Keq = f (T), equilibrium is based on the stoichiometry of the reac tion. Keq = estimated or specified Minimization of Gibbs free energy of all comp onents where the parameters of the reverse reaction must be thermodynamically co nsistent. Heterogeneou Yang and Hougen Form: This form includes Langmuirs Catalytic Hinshe lwood, Eley-Rideal and Mars-van Krevelen etc. Simple Rate In Keq which is estima ted from equilibrium data. The HYSYS reaction rates are given in units of volume of gas or liquid phase dep ending on the stage at which the reaction takes place. For example if you have t he expression of the reaction locity per kg of catalyst, to convert units of vol ume of gas kgcat: IMPORTANT TIPS • The reactions are defined in the Simulation Basis Environment may be associate d with several reactors. • When making changes to a reaction from a reactor, the  change is local and only assumes that unit. • If changes are made to a reaction  from the Simulation Basis Environment or package of reactions these changes are  reflected in all the reactors that use this IMPORTANT TIPS • You must specify the phase in which the reaction is carried. OVERALL option is  for reactions in liquid-gas phase simultaneously. • It must involve a package o f fluids to the set of reactions, if this is not done by default is associated w ith the main package. • You must attach to substances in September

In HYSYS, there are two kinds of reactors: - Ideal - General. 7.2 TYPES OF REACTORS IN HYSYS This type of reactor can be associated only with any of the models using reactio n kinetic parameters. 7.2.1 IDEAL REACTORS PFR The PFR (Plug Flow Reactor, or Tubular Reactor) usually consists of a tube bank.  Plug flow is assumed, which accomplice that the flow in the radial direction is  isotropic (no gradient of mass or energy). Axial flow is neglected. When reacta nts traverse the length of the PFR reactor are continuously consumed and there i s an axial variation of concentration. • For the solution of the PFR and profiles through the length of the reactor, th is is divided into several subvolumens (default 20 subvolumens in HYSYS). • The EDO's RPF are a recent addition to the simulation packages and are resolved by d ividing the volume in small segments and find a solution sequence for each volum e. • Comprised of a series of tubes packed with catalyst and surrounded by a she ll with thermal fluid, the main application is presented in the simulation of re active systems in catalytic bed. Must be specified in a PFR: • Geometric parameters (number of tubes, diameter an d length of the tubes, diameters and sphericity of the catalyst, etc. ..) • Char acteristics of the thermal fluid (flow, temperature input and output, etc. .. ) or exit temperature of their products or the amount of heat transfer and pressur e output • products or the pressure drop inside. • reaction and rate law SIZE • To size a PFR must specify two of the following parameters: total volume, leng th and diameter. The third value is calculated from the two specified. • Specify  the total number of tubes in the PFR. - Wall Thickness in the field to specify the thickness of the tube. • Specify the fraction of empty space (Void fraction)  in the PFR. If this fraction is less than one is required to specify the data o f the catalyst. The empty space of the reactor is calculated from the volume and  the fraction of empty space. Notes: If not specified a current of energy is considered adiabatic operation. - If you select the button Ergun Equation for a PFR with no solid catalyst, fixe d Hysys pressure drop to zero. - Single Phase Active checkbox when the reaction is carried out in one step. If this option is inactive Hysys considers that the reaction is carried out Simulation of an Adiabatic PFR Styrene is a monomer used in the production of di fferent plastics. Styrene is produced from the dehydrogenation of ethylbenzene: C6 H5 - ⇔ C2 H5 C6 H5-CH = CH2 H2 In this reactor will not consider the fact tha t the above reaction is an equilibrium reaction and this system will be modeled using the expression Kinetics of Speed (Kinetic Rate): Note that the reaction rate has units and the term of the partial pressure conce ntration with units of kPa. C6 H5 - ⇔ C2 H5 C6 H5-CH = CH2 H2 1. Start HYSYS 2. Create the list of components

3. Creating a Fluid Package, use the Peng-Robinson thermodynamic package. 4. Reactions on the label of the Simulation Basis Manager, Press the Add button to insert rxn dehydrogenation reaction. The following window displays with viewer reactions in which you select Kinetic. 7. Open-label and matrix Stoichiometry Stoichiometry and Rate Info, select the C omponent column. Enter in this column the components involved in the reaction, t he column automatically appears Mole Wt. Then put the values of the stoichiometric coefficients in column Stoich coeff, c onsidering negative values for reactants and positive for products. 8. Go to the label and set Basis: The units of pressure (Basis Units) are as Partial Pressure kPa Basis The Base C omponent is the E-Benzene vapor phase reaction. The units for the rate law (Rate  Units) are gmole / Ls). All of the above is known from the law 9. Parameters on the label to add the pre-exponential factor A (no units) and th e activation energy E in units of cal / mol (which is transformed to kJ / mol af ter admission). Beta cell leave blank or enter zero. Note that negative sign is not entered in the pre-exponential factor. 10. Close the display properties 11.Create a set of reactions for this case (Add  Set). HYSYS provides the name September 1 and open the property view of the Reaction S et. 12. To assign the newly created Reaction to the Reaction Set, place the cursor i n the cell on Active List. Scroll down the list of reactions and select the name of the reaction (Reaction kinetic). The Set Type is the type of reactio n you have added to the Reaction Set. The message presented at the Ready state n ow. 14. To attach the Reaction Set to Fluid Package (thermodynamic model of Peng Rob inson), highlight to September 1 in Reaction Sets and click the Add to FP. React ion in September when a particular is attached to a Fluid Package, it becomes av ailable for the operating units within the flowsheet using the particular Fluid Package. 17. Now enter the simulation window by pressing the Enter Simulation Environment  ... 18. Place the PFR reactor. There are two ways: - flowsheet (F12) / Add Oper ation / Plug Flow Reactor "From the Objects palette 19. Specify Input current: pure reason Ethylbenzene 152.2 gmol / s and the condi tions of 880 K and 1378 bar. The bottom bar (red) indicates the following errors Reaction Requires Seth 20. Then add the September 1 reactions by clicking on the label Reactions. And the bottom bar shows Unknown Dimensions 21. Go to the rating label and specify the volume, in this case the volume is 0. 77 m3 and 3.00 m length

22. Returning to the label on page Design Parameters and specify that this react or has no pressure drop and is an adiabatic reactor. The bottom bar turns green with the word OK 23. Upon entering the simulation window will have the PDF of the PFR reactor wit h fully specified currents. RESULTS 23. Upon entering the composition of the current Workbook. we 24. For operation of the reactor, we click on the tag Ops Unit and then View Unitop Then click on Plot .. Select the variable you wish to graph and the component is In the Parameters tab, there are many options to plot the behavior of the variab les with the length of reactor CSTR The estimated CSTR conditions the output currents whereas reactor is perfectly m ixed and that the concentration at each point of the reactor is the same. It can  be used for reactions in liquid or gaseous phase, but should be specified. The CSTR model is a standard algebraic model has been in the simulation packages  for many years. To specify the reactor is necessary to associate one or more re actions and specify: Reactor volume level of liquid product outlet temperature o r pressure heat transferred out of the products or the pressure drop inside. The  stoichiometry of the reaction parameters of the reaction rate of each reaction. SIZE You must specify at least one of the following measures: volume, diameter or hei ght (height specified in horizontal tank). Notes • If you specify the cylindrical volume of the tank then by default the length /  diameter of reactor CSTR is 3:2. • The height of liquid in a vertical cylindric al tank varies linearly with the volume of liquid. • The relationship between he ight and volume of fluid is not linear in horizontal cylindrical and spherical t anks. Exercise: will be held the following vapor-phase reaction in an adiabatic CSTR reactor. C6 H5 - ⇔ C2 H5 C6 H5-CH = CH2 H2 The units for the rate law (Rate Units) are gmole / Ls). The reactor is a vertical cylindrical tank reactor volume is 5 m3. No heat loss.  There is no pressure drop. The liquid level in the tank is 50% Food delCorrient e. Temperature Pressure Flow molar mass fraction EBenzene atm 800 ° C 506.6 10 mol / h 1 Solution: "These reactors work with models that do not use reaction kinetic parameters. "T he general reactors are fundamentally a phase separator that is associated with a set of reactions. "This type of reactor can be associated with any of the reac

tion models presented. To specify, you must associate one or more reactions and indicate: Container volume level of liquid product outlet temperature or heat tr ansfer. Product outlet pressure or the pressure drop inside. 7.2.2 GENERAL REACTORS - Hysys has four types of reactors kinetic mate in the palette of objects and th at deploys General Reactors option: • • • • Gibbs Reactor Conversion Equilibrium  Reactor Reactor Reactor Yield Shift REACTOR FOR GIBBS Gibbs Reactor calculates the equilibrium composition of output current while min imizing the Gibbs free energy of the input current. It is only necessary to spec ify the stoichiometry. By minimizing the free energy of the reaction occur more likely. This is spontaneous in nature. • With the Gibbs Reactor obtained similar results with an Equilibrium Reactor if  given correct information but in the Gibbs reactor is not required Keq expressi on depending on the temperature. In this case only the reagents react and not th e products (in the reaction. Versa). • The Gibbs reactors do not require • Exercise: Carry out the above reaction in a Gibbs reactor under the same opera ting conditions. REACTOR OF BALANCE Equilibrium Reactor In determining the composition of output current specifying the stoichiometry of the reactions that occur and the values of the equilibrium constant and its dependence on temperature for each reaction. Equilibrium Reactor can be associated only with equilibrium reaction models. Hys ys has several equilibrium reactions in a list with all the necessary parameters . CONVERSION REACTOR This type of reactor can be associated only with conversion reaction models. You  must specify the stoichiometry of all reactions are carried out and the convers ion of base component, the estimated conversion reactor compositions of the curr ent • Exercise: Hold the vapor phase reaction of ethylbenzene dehydrogenation in a c onversion reactor, where conversion of ethylbenzene is 80%. Yield Shift Reactor The reactors are to model performance using data tables reactors to develop esti mates. This unit can be used for complex reactors that do not have available a m odel or those that exist are expensive. Chemical Reactions and Reactors in HYSYS HYSYS Reactor PFR CSTR Reactor Conversion Reaction Types Conversion% (x% = C0 C1 T C2T2) Simple Rate, Heterogeneous Catalytic, Kinetic Simple Rate, Heterogeneous  Catalytic, Kinetic Keq = f (T); The balance is based on the stoichiometry of th e Keq = Dear reaction from the Gibbs free energy Keq = Specified as a constant o r from a minimization of the Gibbs free energy values specified table. All compo nents there are two options: 1) It is required for the reaction stoichiometry 2)  The stoichiometry of the reaction is given Equilibrium Reactor

Gibbs NOTES: Note that the type of reactor the required specifications are different. The ide al reactors (CSTR and PFR) need to specify the parameters of the rate law and st oichiometry of reactions Tanks, Separators and operations of three-phase separat ion can also carry out reactions. REFERENCES • Copyright © 2004 Hyprotech, a Subsidiary of Aspen Technology Inc. All rights r eserved. • HYSYS 2004 HYSYS. User Guide. • MONCADA, Luis. Process Simulation wit h HYSYS. 2006. of