Plug flow reactors visual encyclopedia of chemical. Reactor design andrew rosen may 11, 2014 contents 1 molebalances 3. The plug flow reactor p fr process is used to estimate the key unit operation. The equations that describe the behavior of a plug flow reactor are material and energy balances. General start up procedure was performed before conducting the experiments. Versatile test reactor update nuclear energy advisory committee. Essentially no back mixing is assumed with plugs of fluid passing through the reactor. Pdf che506 lab report on plug flow reactor l5 2018. Plug flow is obtained when the fluid velocity is constant across a plane normal to the flow direction. For all irreversible reactions of greater than zero order, the volume of the reactor approaches.
Solving odes in matlab the distance from the inlet z is the independent variable. The necessary and sufficient condition for plug flow is for the residence time in the reactor to be the same for all elements of fluid. It makes use of a laminarflow tubular reactor lftr through consecutive lab sessions. Many plants and company used pfr as the site for their reactants to react in producing valuable desired product. Plug flow can be approached in the following cases. The plug flow reactor model pfr, sometimes called continuous tubular reactor, ctr, or piston flow reactors is a model used to describe chemical reactions in continuous, flowing systems of cylindrical geometry. There are a few other disadvantages associated with the. Pictured below is a plug flow reactor in the form of a tube wrapped around an acrylic mold which is encased in a tank. Numerical integration strategies of pfr dynamic models. Feed flow rate of the naoh and the etac was set to be the manipulated. Size reactors either alone or in series once given the molar flow rate of a, and the rate of reaction, r a, as a function of conversion, x.
The result was used to determine the number of equal sized ideal continuous stirred tank reactor cstr arranged in series. These types of reactors are useful for fast reactions that could not be as easily observed in a batch environment. In this experiment naoh and et ac solution are used which result the saponification process. Sketch of the plug flow model of a plasma chemical reactor. Derivation of the generalised equation that describes the behaviour of a plug flow reactor pfr. Advantages of pfrs include high volumetric unit conversion and the capability of running for longer periods without any. The integral to calculate the pfr volume can be evaluated using a method such as simpsons onethird rule pg 925. Unsubscribe from visual encyclopedia of chemical engineering equipment.
The pfr model is used to predict the behavior of chemical reactors of such design, so that key reactor variables, such as the. A loop reactor is a hybrid type of catalytic reactor that physically resembles a tubular reactor, but operates like a cstr. Manual for che 496 information services new jersey institute. Experimental study of the influence of process conditions on. A radial flow pattern is used to minimize the pressure drop. The three main reactor types developed thus far batch, continuousstirredtank, and plugflow reactors are useful for modeling many complex chemical reactors. Plug flow reactor is characterized by the fact that the flow of fluid through the reactor is orderly with no element of fluid overtaking or mixing with any other element ahead or behind. The pfr model is used to predict the behavior of chemical reactors of such design, so that key reactor variables, such as the dimensions of the reactor, can be estimated. This radial flow design gives a large flow area and minimizes the pressure drop through the catalyst. 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. Make sure you have the preexperiment plan in the notebook before starting each new. Bilge alpaslan kocamemi if the series is composed of one reactor complete mix regime prevails if the series consists of an infinite number plug low regime prevails.
The unit comes complete with vessels for raw materials and product, feed pumps, and thermostat. Chemical reaction engineering part intro to plug flow. That means a plug of conservative dye introduced at one end will remain intact as it passes through the reactor fig. The number of ideal stirred tanks that will fit the rtd data of the nonideal plug flow reactor simply means the number of. Normal butane, c 4 h 10, is to be isomerized to isobutane in a plugflow reactor. The volume of a pfr can be represented as the shaded area in the levenspiel plot shown below. The plug flow reactor is an ideal model for a tubular flow reactor. An empty pipe is a poor continuous reactor because the material in the center of the pipe travels at twice the average velocity resulting in.
Data from the following table were obtained for the gas phase decomposition of reactant a in a constant volume batch reactor at 100c fed with pure a. Presented by professor alan hall, university of huddersfield. The system may be either contained as in a water main, oil pipeline, or blood. In a plug flow reactor, nutrients and sometimes organisms are introduced to the reactor continuously and move through the reactor as a plug. Normal butane, c 4 h 10, is to be isomerized to isobutane in a plug flow reactor. The second method used consists of a water bath of controlled temperature where the reactants are heated to the required temperature before they were fed to the reactor which was also heated to the same temperature using the water jacket. Thus the volume of solution that flow into the reactor equal to the volume of the solution out from the solution. Feb 27, 20 plug flow reactor design with matlab posted in student. The composition of the reactor mixture is constant through the cross section of the reactor radial and no mixing of the reactants occur in the flow direction axial plug flow. In the case of tube flow, the accepted ideal is the plug flow reactor, in which it is assumed that there is no mixing in the axial flow direction but perfect mixing in the directions transverse to this. View enhanced pdf access article on wiley online library html view. Reactors jordan university of science and technology. This file is case specific and is adjusted to the reaction network.
Experimental study of the influence of process conditions. The example details the use of the predefined plugflow reactor type in the. Plug flow is an ideal case and could only be exactly obtained in the lab with, e. Department of chemical engineering jeppiaar nagar, chennai 119. The plug flow reactor pfr is a tubular reactor operated at steady state and has axial gradients but no radial gradients.
Pdf the temperaturescanning plug flow reactor tspfr applied. This reactors primary purpose it to be used to demonstrate the use of the constantly stirred tank reactor cstr, the plug flow reactor pfr, and the batch reactor, common reactor tropes in chemical engineering. Uytengsu teaching center chemical reactor standard. The design of a chemical reactor deals with multiple aspects of chemical engineering. The unit consists of jacketed reaction fitted in the agitator and condenser. Plug flow reactor design with matlab posted in student.
In chemical reactors engineering, the introduction of axial dispersion is a recognized tool to implement real flow conditions in an ideal plug flow reactor pfr model, which assumes fluid molecules to have a flat velocity profile at any given position along the tubular reactor axis, i. Though the oral presentation can follow any format e. Apr 05, 2017 reactors plug flow reactor visual encyclopedia of chemical engineering equipment university of michigan. This demonstration calculates conversion as a function of reactor volume for a secondorder, gasphase reaction in an isothermal, isobaric, plug flow reactor pfr. A chemical reactor is an enclosed volume in which a chemical reaction takes place. Plug flow reactor design with matlab student cheresources. Versatile test reactor update nuclear energy advisory. The rates of reaction are also evaluated, and the function returns the numerical value of the right hand side. These reactors provide enough residence time for the reaction to take place with satisfactory conversion. Whith an infinite number of tanks the dependance of the concentration of the cascade of stirred tank reactors is equivalent to the plug flow reactor. In chemical engineering, it is generally understood to be a process vessel used to carry out a chemical reaction, which is one of the classic unit operations in chemical process analysis.
Given r a as a function of conversion, one can size any type of reactor. A chemical reaction engineering laboratory experiment. Principles of chemical reactor analysis and design. This happens when kinetics data for a single reaction are generated using either a batch reactor or a plug flow reactor. In such reactors, the reaction rate expression must be known determined. Reactors plug flow reactor visual encyclopedia of chemical engineering equipment university of michigan. Pdf lab report tubular flow reactor muhamad faizzudin. In addition to excellent radial mixing, continuous reactors require plug flow conditions. Bilge alpaslan kocamemi if the series is composed of one reactor complete mix regime prevails if the series consists of an infinite number pluglow regime prevails. The object of this experiment is to study the behaviour of a plugflow reactor by performing a series of experiments on the saponification of ethyl acetate. Numerical integration strategies of pfr dynamic models with. Pdf the temperaturescanning plug flow reactor tspfr enables the investigation of kinetics. Distributions of residence times for chemical reactors.
Batch reactor is an essential operation unit of scale laboratory pilotplants, since it is convenient for smallscale operation, for testing new processes that have not been fully developed, for the manufacture of expensive products and for processes that are difficult to convert to continuous operations. This reactor s primary purpose it to be used to demonstrate the use of the constantly stirred tank reactor cstr, the plug flow reactor pfr, and the batch reactor, common reactor tropes in chemical engineering. Two commonly used reactors are the cstr continuous stirred tank reactor and the pfr plug flow reactor. Chemical reactor is known as the heart of any chemical plant since the new chemicals are produced only in this vessel and the economics of the entire plant depends on the design of reactor. Batch reactor is an essential operation unit of scale laboratory pilotplants, since it is convenient for smallscale operation, for testing new processes that have not been fully developed, for the manufacture of expensive products and for processes that. In this reactor the catalyst is contained between 2 vertical cylindrical screens. The object of this experiment is to study the behaviour of a plugflow reactor by. Plug flow reactors usually operate in adiabatic or nonisothermal conditions mi nsker and et.
Cstr continuous stirred tank reactor and the pfr plug flow reactor. The model is applied here for conditions of the experiment described in. The plug flow model has many practical applications. Calculate the size of the plug flow reactor, operating at 100c and 1. Several typical deviations from the ideal behaviour of the stirred tank reactor and plug flow reactor are shown diagrammatically in the figures above. The gas flows from the inner vertical cylinder, through the catalyst, to the outer cylinder. The plug flow reactor is more complex than the continuousstirred tank alternative with regard to operating conditions. The reaction mixture is circulated in a loop of tube, surrounded by a jacket for cooling or heating, and there is a continuous flow of starting material in and product out. Up to this point we have neglected a careful treatment of the fluid flow pattern within the reactor. A cailed tubular reactor for nonnewtonian flow n 0. Water at a controlled temperature is circulated through the tank to maintain constant reactant temperature. Selection of technical reactor equipment for modular. Plug flow, or tubular, reactors consist of a hollow pipe or tube through which reactants flow. Laminar vs plug flow 3 laminar flow has a distribution of speeds and residence times plug flow is a simplification for analysis purposes turbulent flow is closer to plug, but more wall contact.
We expect to see a continuous change in the concentration of the effluent stream until, after a long time, it matches the. In plug flow reactors, reactants are fed from one end of reactor and flows continuously through the length of reactor as a series of plugs and the products are discharged from the other end of reactor. Ideal plug flow reactor assumptions theoretically, the solution of the governing equations is an initialvalue problem any single matching point of experiment and theory should be equivalent where is time 0 for the problem. Chemical reaction engineering cre deals with the design of chemical reactors to produce chemicals. In addition to excellent mixing, continuous reactors require plug flow conditions which means that all the material processed through the reactor has the same residence time. Feed flow rate of the naoh and the etac was set to be the manipulated variable where the flow rates were varied to 50 mlmin, 100 mlmin, 150 mlmin, 200 mlmin, 250 mlmin and 300 mlmin. Laminar vs plug flow 3 laminar flow has a distribution of speeds and residence times plug flow is a simplification for analysis purposes. Why density change cannot be ignored in a plug flow. Since the reactor is plug flow reactor, the process is 10 continuous, flowing system. The plug flow model assumes there is no boundary layer adjacent to the inner wall of the pipe. Plug flow conditions means that all the material processed through the reactor must have the same residence time so that the chemicals exiting the reactor have witnessed the same reaction conditions of reactive species contacttime agingtemperature history.
A reactor of this type is called a plugflow reactor pfr and. At time zero we start adding a small flow of a tracer to the feed stream and measure the tracer concentration in the effluent stream. The number of moles increases as conversion increases for the reaction, and this causes the mass density to decrease. I am designing a pfr reactor using matlab, need some advise. The plug flow reactor model pfr, sometimes called continuous tubular reactor, ctr is normally the name given to a model used in chemical engineering to describe chemical reactions in continuous, flowing systems of cylindrical geometry. In this lecture we explore some of the limits of this. Why density change cannot be ignored in a plug flow reactor. Ideal plug flow reactor characteristics of ideal plug flow perfect mixing in the radial dimension uniform cross section concentration no mixing in the axial direction, or no axial dispersion segregated flow tracer pulse input at t 0 translated to equal pulse output at t lv l pfr length, v average velocity.
For a small number n of tanks the residence time for a large part of the molecules differs from the mean residence time broad residence time distribution. In addition, two modes of reactor operations were considered. Write the mole balances in terms of conversion for a batch reactor, cstr, pfr, and pbr. Like unit 14, unit 15 considers the situation where the model for a set of kinetics experiments takes the form of a differential equation. A plug flow reactor plug flow is an extremely simple tool, but were going to put it to use anyway. The long tube and the lack of provision for stirring. Department of chemical engineering jeppiaar nagar, chennai. The plugflow reactor pfr is a tubular reactor operated at steady state and has axial gradients but no radial gradients. At steady state the concentration is all times constant at every point of the flow reactor.
The pfr model is used to predict the behaviour of chemical reactors of tubular design, so that key reactor. Water at a controlled temperature is circulated through the. Reactor model for laboratory reactor reactor model for plant reactor 10 m. Plug flow reactor model of the plasma chemical conversion of co2. The idealized plugflow and batch reactors are the only two classes of reactors in which all. The long tube and the lack of provision for stirring prevents complete mixing of. Uytengsu teaching center chemical reactor standard operating. Consider a simple rectangular reactor which has a gas inlet on one side, an exhaust on the other, and deposition on the top and bottom walls and the sample, resting on the bottom surface. A laminar flow reactor lfr is a type of chemical reactor that uses laminar flow to control. Measurement of the concentration changes of the tracer response function is usually performed using methods from colorimetry, photometry, electrical conductivity or isotopic marking. After the flow field is obtained, a tracer experiment is simulated by scalar. When the material is starting to reach the outlet, the concentration drastically increases, and it gradually. It can be shown2 that the absence of axial mixing allows the achievable reactant conversion to be maximized.
The reactor flux into the element is defined as jin uc 2. Conversion and reactor sizing define conversion and space time. Since the concentration varies continuously down the reactor tube, so does the reaction. In an ideal pfr, is the absolute residence time for mass flowing through the reactor, not the average residence time as in a cstr. Assessing the degree of plug flow in oxidation flow reactors ofrs. The reactor should not be used for any other purpose besides lab demostrations.
In the case of a plug flow, the dispersion model accounts for axial dispersion d, which is the physical parameter that quantifies axial backmixing and shortcircuiting of fluid. A packedbed plugflow reactor, denoted as the labscale. Reactor theory and practice plug flow reactor pfr the third general type of reactor is the plug flow reactor pfr. The example details the use of the predefined plug flow reactor type in the. The object of this experiment is to study the behaviour of a plug flow reactor by performing a series of experiments on the saponification of ethyl acetate. New tools for industrial chemical reactor operations, second edition. An empty pipe is a poor continuous reactor because the material in the center of the pipe travels at. An integrated chemical engineering lab experiment is described in this paper. The continuous stirred tank reactor model bp 143 unit is suitable for student experiments on continuous chemical reactions.
638 1002 1177 566 688 1385 1105 253 300 73 663 1154 638 1195 16 457 1228 1045 381 1198 1089 4 700 1043 198 1525 1489 97 559 622 39 987 511 61 1026 1087 289 394