7/18/2019 ChE410_PFRhgfhgf

http://slidepdf.com/reader/full/che410pfrhgfhgf 1/2

 

METU Chem. Eng. Dept.

Ch.E. 410 Chem. Eng. Lab II

EXPERIMENT 3.2.

TUBULAR FLOW REACTOR

1/2

OBJECTIVES

1.  To determine the rate law using tubular flow reactor data.

2.  To demonstrate the temperature dependence of the reaction and the rate constant.

3.  To understand tubular flow reactor performance.

BACKGROUND INFORMATION

In the majority of industrial chemical processes, the reactor is the key item of equipment

in so far that the required chemical change of raw materials to form desired products

occur at this point in the whole process. The design and operation of chemical reactors are

thus crucial to the whole success of the industrial operations.

Tubular flow reactors are commonly used in the industry. If the flow field in a tubular

reactor is highly turbulent plug flow assumption is generally made in the design of such

reactors (Fogler, 1992; Smith, 1981; Levenspiel, 1972). Due to mixing in the longitudinal

direction and incomplete mixing in the radial direction, deviations from ideal tubular flow

(plug flow) behaviour are possible. The reaction chosen in this experiment is the

saponification of ethyl acetate (EtOAc) with dilute sodium hydroxide (NaOH):

NaOH + EtOAc→ NaOAc + EtOH

EXPERIMENTAL

Equipment: The equipment that will be used in the experiments is an Armfield CET-Tubular Flow Reactor. Description of the equipment and details of the operating

instructions are available in the Instruction Manual. A tubular reactor of length 22 m andvolume 0.4 lt is placed in a constant temperature water bath. Temperature of the reactor

was adjusted to the desired value by controlling the water bath temperature which isheated by heating elements. Two feed tanks contain the reactants which are pumped by

the two positive displacement type pumps through the flowmeters into the inlet feed

pipes. From here they enter the reactor coil. The mean residence time in the coil is a

function of the flowrate, set by the flowmeters. Control of the equipment which is situated

on the front panel, is governed by a mains on/off switch, pump switches, a temperature

scale and stirrer motor switch. (See the manual)Supply: The chemicals needed in the experiments are 0.1 M NaOH, 0.1 M HCl, 0.1 M

EtOAc and phenolphthalein indicator. Additional equipment needed in the analysis of thereactants and products are: flasks, pipette, burette, graduate cylinder.

7/18/2019 ChE410_PFRhgfhgf

http://slidepdf.com/reader/full/che410pfrhgfhgf 2/2

METU Chem. Eng. Dept.Ch.E. 410 Chem. Eng. Lab II

Experiment 3.2.Tubular Flow Reactor

2/2

Procedure:

1.  Carry out reaction experiments in the tubular reactor using equal molar flowrates of

the reactants. Repeat these experiments at 4 different space times. Analyze inlet and

outlet concentrations of NaOH. In each run obtain data at different times until steady

state is reached.2.  Repeat tubular flow experiments at 4 different temperatures.

TAKE HOME

1.  You are expected to determine the fractional conversion values in each experiment.

2.  You should determine the reaction order and rate constants.

3.  You should determine the activation energy and an expression for the temperaturedependence of the rate constant.

4.  You should calculate the Reynold’s and Peclet numbers in your reactor. Comment

and discuss whether deviations from ideal plug flow behaviour are significant or not.

Compare the ideal plug flow reactor volume with the real one. (Ref.3).

NOTE: Bring a graph paper to the experiment.

PRELIMINARY WORK (to be prepared on the notebook)

1.  How can you analyze reactants and products of a saponification reaction by titration?

2.  Derive the design equation of a plug flow reactor.

3.  Read the instruction manual.

4.  Make an experimental plan before performing the experiment. Discuss the type ofexperiment you would carry out to find the rate law (rate constant and rate order in

PFR).

5.  How can you find the activation energy of this reaction?

6.  Read Chapter 13 (p. 293-296, 309-317) in Levenspiel related to axial dispersion.

REFERENCES

1.  Smith, J.M., Chemical Engineering Kinetics, McGraw Hill Int., 1981.

2.  Fogler, H.S., Elements of Chemical Reaction Engineering, Prentice-Hall Inc., USA,

2nd Ed, 1992.

3.  Levenspiel, O., Chemical Reaction Engineering, Third ed.,John Wiley and Sons, New

York, 1999.4.  Armfield CET-Tubular Flow Reactor, Instruction Manual, 1993.