CHEMICAL ENGINEERING '«r f I»' CD'RQM Elements of Chemical INCLlfflEO Reaction Engineering 5 H. Scott Fogler H. Scott Fogler Third Edition Applied. (Original U.S. Edition-Rs. ). ELEMENTS OF CHEMICAL REACTION ENGINEERING, 3rd Ed. (with CD-ROM) by H. Scott Fogler. C by Prentice- Hall. Elements of chemical reaction engineering / H. Scott Fogler.—Fifth edition. pages cm. Includes index. ISBN (hardcover: alk. paper). 1.
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DENSITIES OF AQUEOUS INORGANIC SOLUTIONS AT 1 ATM. Units and Units Enthalpy–Log-Pressure pdf. H. Scott Fogler Essentials of Chemical Reaction Engineering - Ebook download as PDF File .pdf), Text File .txt) or read book online. Essentials of Chemical. Today's Definitive, Undergraduate-Level Introduction to Chemical Reaction Engineering Problem-Solving For 30 years, H. Scott Fogler's Elements of Chemical.
It will give students a flavor of the top selling chemicals and top chemical companies. This problem will be useful when the table is completed and the students can refer back to it in later chapters. See Pl Many students like this straight forward problem becausethey see how CRE principles can be applied to an everyday example. It is often assigned as an in classproblem and part g is usually omitted. Problems Pl-ll and PI show a bit of things to come in terms of reactor sizing.
Can be rotated from year to year with PI-3 and PI Asks for details of operation of an industrial reactor. Encouragesand requires the student to go outside the text for information related to CRE.
It is straight forward and gives the student an idea of things to come in terms of sizing reactors in chapter 4. SeePl-3 above. This problem can be assigned to just be read and not necessarily to be worked. It will give students a flavor of the top selling chemicals and top chemical companies. This problem will be useful when the table is completed and the students can refer back to it in later chapters. See Pl Many students like this straight forward problem becausethey see how CRE principles can be applied to an everyday example.
It is often assigned as an in classproblem and part g is usually omitted.
Problems Pl-ll and PI show a bit of things to come in terms of reactor sizing. Some of the examples that illustrate the wide application of CRE principles in this book are shown in Fig- ure Also shown are the manufacture of ethylene glycol anti- freeze. Other examples shown are the solid-liquid kinetics of acid-rock interactions to improve oil recovery Chapter 7. In this chapter. After defining the rate of reaction. The structure shown illustrates the kind. Even though two chemical compounds have exactly the same number of atoms of each element.
The term chemical species refers to any chemical component or element with a given identity. This chapter develops the first building block of chemical reaction engineering.
The CH 3 identity of a chemical species is determined by the kind. This accounting process is achieved through overall mole balances on indi- vidual species in the reacting system. Section 1. As a consequence of the different configurations, these two isomers display different chemical and physical properties.
Therefore, we consider them as two different species, even though each has the same number of atoms of each element. When has a We say that a chemical reaction has taken place when a detectable num- chemical reaction ber of molecules of one or more species have lost their identity and assumed a taken place?
In this classical approach to chemical change, it is assumed that the total mass is neither cre- ated nor destroyed when a chemical reaction occurs. The mass referred to is the total collective mass of all the different species in the system. However, when considering the individual species involved in a particular reaction, we do speak of the rate of disappearance of mass of a particular species.
The rate of disappearance of a species, say species A, is the number of A molecules that lose their chemical identity per unit time per unit volume through the breaking and subsequent re-forming of chemical bonds during the course of the reac- tion.
Prof. Fogler's Lecture Notes
In order for a particular species to "appear" in the system, some pre- scribed fraction of another species must lose its chemical identity. There are three basic ways a species may lose its chemical identity: In decomposition, the mole- cule loses its identity by being broken down into smaller molecules, atoms, or atom fragments. For example, if benzene and propylene are formed from a cumene molecule,.
A second way that a molecule may lose its spe- cies identity is through combination with another molecule or atom.
In the above reaction, the propylene molecule would lose its species identity if the reaction were carried out in the reverse direction, so that it combined with ben- zene to form cumene. Here, although the molecule neither adds other molecules to itself nor breaks into smaller molecules, it still loses its identity through a change in configuration. To summarize this point, we say that a given number of molecules i. The rate at which a given chemical reaction proceeds can be expressed in several ways.
To illustrate, consider the reaction of chlorobenzene and chloral to produce the banned insecticide DDT dichlorodiphenyl-trichloroethane in the presence of fuming sulfuric acid. The numerical value of the rate of disappearance of reactant A, -rA, is a posi- tive number. What is -rA? The rate of reaction, -rA, is the number of moles of A e. Chloral is being consumed at a rate of 10 moles per second per m3 when reacting with Chlorobenzene to form DDT and water in the reaction described above.
Solution a Chloral[A]: For every mole of chloral that disappears two moles of chlorobenzene [B] also disappear.
For every mole of chloral that disappears one mole of DDT[C] appears. Same relationship to chloral as the relationship to DDT. The purpose of this example is to better understand the convention for the rate of reaction.
The symbol rj is the rate of formation generation of species. If species The convention j is a product, then rj will be a positive number. The rate of reaction, - r A, is the rate of disappearance of reactant A and must be a positive number.
Heterogeneous reactions involve more than one phase. In heterogeneous reaction systems, the rate of reaction is usually expressed in measures other than volume, such as reaction surface area or catalyst weight. For a gas-solid catalytic reaction, the gas molecules must interact with the solid catalyst sur- face for the reaction to take place, as described in Chapter Most of the introductory discussions on chemical reaction engineering in this book focus on homogeneous systems, in which case we simply say that rj Definition of rj is the rate of formation of species j per unit volume.
It is the number of moles of species j generated per unit volume per unit time. We can say four things about the reaction rate r j. The chemical reaction rate law is essentially an algebraic equation involving concentration, not a differential equation. Crynes and H. Fogler, eds. Kinetics, I, I New York: AIChE, ; and R. Kabel, "Rates," Chern. For a given reaction, the particular concentration dependence that the rate law follows i. Equation states that the rate of disappearance of A is equal to a rate constant k which is a function of temperature times the square The convention of the concentration of A.
As noted earlier, by convention, rA is the rate of for- mation of A; consequently, -rA is the rate of disappearance of A. Throughout this book, the phrase rate of generation means exactly the same as the phrase rate of formation, and these phrases are used interchangeably. The volume enclosed by these boundaries is referred to as the system volume.
We shall perform a mole balance on species j in a system volume, where species j represents the particular chemical species of interest, such as water or NaOH Figure System Volume, V. A mole balance on species j at any instant in time, t, yields the following equation:. If all the system variables e. Now suppose that the rate of formation of species j for the reaction varies with position in the system volume.
That is, it has a value r j 1 at location 1, which is surrounded by a small volume, 1: Similar expressions can be written for l:! Gj2 and the other system subvolumes, 1: The total rate of generation within the system volume is the sum of all the rates of generation in each of the subvolumes.
By taking the appropriate limits i. From this equation we see that r j will be an indirect function of position, since the properties of the reacting materials and reaction conditions e. We now replace Gj in Equation From this general mole balance equation, we can develop the design equations for the various types of industrial reactors: Upon evaluation of these equations, we can determine the time batch or reactor volume continuous-flow necessary to convert a specified amount of the reactants into products.
The reactor can be charged i. The batch reactor has the advantage of high conversions that can be obtained by leaving the reactant in the reactor for long periods of time, but it also has the disadvantages of high labor costs per batch, the variability of products from batch to batch, and the difficulty of large-scale production see Professional Reference Shelf [PRS] on the DVD-ROM and Web.
Hand holes for charging reactor. Connection for. A batch reactor has neither inflow nor outflow of reactants or products while the reaction is being carried out: The resulting general mole bal- ance on species j is. If the reaction mixture is perfectly mixed Figure 1-S b so that there is no variation in the rate of reaction throughout the reactor volume, we can take rj out of the integral, integrate, and write the mole balance in the form.
Batch Reactor. This equation is the integral form of the mole balance on a batch reactor. We will consider three types: A type of reactor used commonly in industrial processing is the stirred tank What is a CSTR operated continuously Figure It is referred to as the continuous-stirred used for?
It is normally operated at steady state and is assumed to be perfectly mixed ; consequently, there is no time dependence or position depen- dence of the temperature, concentration, or reaction rate inside the CSTR.
That is, every variable is the same at every point inside the reactor. Because the temperature and concentration are identical everywhere within the reaction vessel, they are the same at the exit point as they are elsewhere in the tank. Thus, the temperature and concentration in the exit stream are modeled as being the same as those inside the reactor. In systems where mixing is highly nonideal , the well-mixed model is inadequate, and we must resort to other modeling techniques, such as residence-time distributions, to obtain meaning- ful results.
When the general mole balance equation. The molar flow rate Fi is just the product of the concentration of species j and the volumetric flow rate v:. Conse- quently, we can substitute for FiO and Fi into Equation to write a balance on species A as. The ideal CSTR mole balance equation is an algebraic equation, not a differential equation. In addition to the CSTR and batch reactors, another type of reactor commonly used in industry is the tubular reactor.
It consists of a cylindrical pipe and is When is a tubular normally operated at steady state, as is the CSTR. Tubular reactors are used reactor most often used? A schematic and a photograph of industrial tubular reactors are shown in Figure In the tubular reactor, the reactants are continually consumed as they flow down the length of the reactor.
In modeling the tubular reactor, we assume that the concentration varies continuously in the axial direction through the reactor. Consequently, the reaction rate, which is a function of con- centration for all but zero-order reactions, will also vary axially.
For the pur- poses of the material presented here, we consider systems in which the flow. Figure 1-S a Tubular reactor schematic.
Figure 1-S b Tubular reactor photo. Longitudinal tubular reactor. Copyright by 1nstitut frant;: McGraw-Hill, lnc. That is, there is no radial variation in reaction rate, and the reactor is referred to as a plug-flow reactor PFR. Plug flow-no radial variations in velocity, concentration. The equation we will use to design PFRs at steady state can be developed in two ways: Let's choose the sec- ond way to arrive at the differential form of the PFR mole balance. Taking the limit as L1 V approaches zero, we obtain the differential form of steady state mole balance on a PFR.
However, we see that by applying Equation , the result would yield the same equation i. For species A, the mole balance is. Consequently, we see that Equation applies equally well to our model of tubular reactors of variable and constant cross-sectional area, although it is doubtful that one would find a reactor of the shape shown in Figure J -1 J unless it were designed by Pablo Picasso.
The conclusion drawn from the applicati, n of the design equation to Pic- asso's reactor is an important one: As the reac- tants proceed down the reactor, A is consumed by chemical reaction and B is produced.
Consequently, the molar flow rate FA decreases, while F 8 increases as the reactor volume V increases, as shown in Figure V1 is the volume necessary to reduce the entering molar flow rate FAa to some specified value FA, and also the volume necessary to produce a molar flow rate of B of F The principal difference between reactor design calculations involving homo- geneous reactions and those involving fluid-solid heterogeneous reactions is that for the latter, the reaction takes place on the surface of the catalyst see Chapter Consequently, the reaction rate is based on mass of solid catalyst, W, rather than on reactor volume, V.
For a fluid-solid heterogeneous system, the rate of reaction of a species A is defined as. The mass of solid catalyst is used because the amount of catalyst is what is important to the rate of product formation. The reactor volume that contains the catalyst is of secondary significance. Figure shows a schematic of an industrial catalytic reactor with vertical tubes packed with solid catalyst.
Figure Longitudinal catalytic packed-bed reactor. As with the PFR.. W is the catalyst weight necessary to reduce the entering molar flow rate of species A.. To accomplish this der- ivation. You can use the integral form only when there is no t!
After dividing by l1 W and taking the limit as l1 W 0. The derivation of the design equation PBR Mole Balance for a packed-bed catalytic reactor PBR will be carried out in a manner analo- gous to the development of the tubular design equation.. When pressure drop through the reactor see Section 5. Derive an equation relating the reactor volume to the entering and ex1ung concentrations of A. Because the volumetric flow rate is constant.
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Solution 1. Sketch CA as a function of V. Species A is consumed as we move down the reactor. Sketch the concentration profile. Example How Large Is It? Consider the liquid phase cis. E l Derive an equation relating V. OlCAo 0. Chapter II. The purpose of the example was to give a vision of the types of calculations we will be carrying out as we study chemical reaction engineering CRE. We see that a reactor volume of 0. We want to find the volume. There are also links to view reactors on different Web sites.
For this irreversible liquid-phase first order reaction i. Calculate V. The more species A consumed and converted to product B. Susan Montgomery and her students at the University of Michigan. We see that a larger reactor dm 3 is needed to reduce the exit con- centration to a smaller fraction of the entering concentration e. Many variations and modifications of these commercial reactors e. The goal of this text is to weave the fundamentals of chemical reaction engineering into a structure or algorithm that is easy to use and apply to a variety of problems.
In addition. The kinetic rate law for rj is: Sl-2 dt 2. A mole balance on species j.. We have just finished the first building block of this algorithm: Chapters 11 through 13 With this algorithm. Smog in L. Web module includes a Living Example Problem.: Summary Notes 2. Smog in L.. Getting Unstuck C. Web Material A. By convention. Problem-Solving Algorithm s. Mole baJances on species A in four common reactors are as follows.
Interactive Computer Games A. Quiz Show I Interactive l: June MAin Menu Continuous stirred tank mactors CSfR am the most basic of the continuous reactors used in chemical processes.
I wish I had an answer for that. Yogi Berra. New York Yankees Sports Illustrated. PA a Revisit Example Suggest two ways to work this problem incorrectly. The Elements of Style. Explain why. Calculate the volume of a CSTR for the conditions used to figure the plug-flow reactor volume in Example You may wish to refer toW. Write a paragraph describing both the content goals and the intellectual goals of the course and text. PA a Read through the Preface.
Strunk and E. Which volume is larger. New York: Chapter 1 Questions and Problems 27 In each of the questions and problems below. Spe- cies A signify? What does a positive number signify? What is the initial concentration of A? Rework this example using Equation on page Figure Pl-3A Batch reactor a Assuming that the ideal gas law is valid.
Write an unsteady mass balance on a the corn steep liquor. The nutrient corn steep liquor enters the cell of the microorganism Penicillium chrysogenum and is decom- posed to form such products as amino acids..
Pl-7 8 We are going to consider the cell as a reactor. Start from a differential mole balance. Look at the QuickTime vid- eos. Play this game and then record your performance number. Write a paragraph describing two or more of the reactors. Discuss any difficulties you encountered and three ways e. What sim- ilarities and differences do you observe between the reactors on the Web e.
Write a paragraph describing what you learned. Assume the cell is well mixed and that RNA remains inside the cell.
Type in "chernicalreactor" to nar- row your search. The basin floor covers approximately square miles 2 x 10 10 ft 2 and is almost completely surrounded by mountain ranges. Use the data in the mod- ule to work parts a through h given in the module. If one assumes an inversion height in the basin of ft. Make a list of the five most important things you learned from this chapter. We shall perform an unsteady-state mole balance on CO as it is depleted from the basin area by a Santa Ana wind.
What assumptions were made in the derivation of the design equation for: There is heavier traffic in the L. For part i. Wind c:: Load the Living Example Polymath code and explore the problem. We shall use this system volume to model the accumulation and depletion of air pollutants.
Elements of Chemical Reaction Engineering, Fifth Edition
Is the reaction rate -rA an extensive quantity? Santa Ana winds are high-velocity winds that originate in the Mojave Desert just to the northeast of Los Angeles.
As a very rough first approximation. Also plot the number of foxes versus the number of rabbits. The predator-prey relationships are given by the following set of coupled ordinary differential equations: See margin figure.
Prof. Fogler's Lecture Notes
These equation solvers will be used extensively in later chapters. Write a paragraph describing what you find. Vary the parameters k 1. Explain why the curves look the way they do.
Combine 6. How many piano tuners are there in the city of Chicago? Show the steps in your reasoning. He used a process to set bounds on the answer by saying it is probably larger than one number and smaller than another and arrived at an answer that was within a factor of These problems could be photocopied and used to help reinforce the fundamental principles discussed in this chapter.
How many square meters of pizza were eaten by an undergrad- uate student body population of Additional problems cf. See http: CA is 0. The volumetric flow rate.
What is the corresponding reactor volume? Solution I. The entering concentration of A. How many bath tubs of water will the average person drink in a lifetime? Novel and Musical Mole Balance 3 dm 3 2 mo! A 6 molA 4. Fermi was famous for his "Back of the Envelope Order of Magnitude Calcu- lation" to obtain an estimate of the answer through logic and making reason- able assumptions.
Enrico Fermi was an Italian physicist who received the Nobel Prize for his work on nuclear processes. Rate Law 2nd order 5. PA What is wrong with this solution?
Intrvduction to Chemical Processes: Upper Saddle River. New York. Shreve 's Chemical Process Industries. Basic Principles and Calculations in Chemical Engineering. Golden Bell Press.. The Anatomy of Skiing. Chapters 2 and 6. McGraw-Hill Higher Education.
Chapter 4. For further elaboration of the development of the general balance equation. A detailed explanation of a number of topics in this chapter can be found in the tutorials.
Elementary Principles of Chemical Prv- cesses. John Wooden. A balance equation was developed for each reactor type and these equations are summarized in Table S-1 in Chapter I. In the first chapter. In Chapter 2. Conversion 2 and Reactor Sizing Be more concerned with your character than with your reputation.. For irreversible reactions. We will take a closer look at equilibrium con- version in Chapter 4. Equation ] proceeds to the right?
For reversible reactions. The conversion XA is the number of moles of A that have reacted per mole of A fed to the system: If NAo is the number of moles of A initially present in the reactor i.
We shall choose species A as our limiting reactant and.. Now we ask such questions as "How can we quantify how far a reaction [e. In virtually all instances we must choose the limiting reactant as the basis of cal- culation. The limiting reactant is the reactant that will be consumed first after the reactants have been mixed.
In the general reaction. Equation Section 2. For batch reactors.
To determine this length of time. Equation ]: The laboratory bomb calorimeter reactor is widely used for obtaining reaction rate data. Carrying out the integration. The differential forms of the batch reactor mole balances.. Equations and Batch reactors are frequently used in industry for both gas-phase and liquid-phase reactions.
To determine the time to achieve a specified conversion X. Liquid-phase reactions are frequently carried out in batch reactors when small-scale production is desired or operating difficulties rule out the use of continuous flow systems. Equation is the differential form of the design equation. CAo is commonly given in terms of molarity. For continuous-flow systems. FAa molls. The preced- I ing sentence can be expressed mathematically as r l lI Molar flow rate.
CAo can be calculated from the entering mole fraction. For an ideal gas see Appendix B: If FAa is the molar flow rate of species A fed to a system operated at steady state. For the general reaction. RTQ Now that we have a relationship [Equation ] between the molar flow rate and conversion. In PBRs it is the weight of catalyst W that is important. This relationship between reac- tion rate and concentration is developed in Chapter 3.
That is. We then express the mole balance equation for species A in the reaction as. Equations and ]. The derivation of the differential and integral forms of the design equations for packed-bed reactors are analogous to those for a PFR [cf. To develop the PFR design equation.
When only one reaction is occurring. The rate of disappearance of A. Equation ] must be used when analyzing reactors that have a pressure drop along the length of the reactor. We note in Equations and that the reactor volume is a function of the reciprocal of -rA. We discuss pressure drop in packed-bed reactors in Chapter 5.
A particularly simple functional dependence. For this first-order dependence.
In the absence of pressure drop. For reversible reactions e. Examples To illustrate the design of continuous flow reactors i. For all irreversible reactions of greater than zero order see Chapter 3 for zero-order reactions..
By sizing we mean either determine the reactor volume for a spec- ified conversion or determine the conversion for a specified reactor volume. The laboratory measurements given in Table show the chemical reaction rate as a function of conversion. Before sizing flow reactors. If a reaction is carried out isothermally. At equilibrium.
More on Xe in Chapter 4. Near the end of the reaction.. A mol 2. We are now going to carry out a number of examples where we have specified the flow rate FAo at 0.
Thjs rectangle is shaded in the figure. Jx In Figure E2-l.
B mol Substitution into Equation for an entering molar flow rate. From either Table or Figure A. Tills volume corresponds to a reactor about 1. Given the conversion. Solution We start by repeating rows I and 4 of Table to produce the results shown in Table It is important to remember that the rate laws are determined by experimental obser- vation! From Figure The next day. Thoroughly classroom tested, this text reflects feedback from hundreds of students at the University of Michigan and other leading universities.
One of the most common general forms of this dependence is the power law model. Thjs rectangle is shaded in the figure. M web module..
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