The construction and testing of a continuous equilibrium flash vaporization apparatus

46 Pages·01.674 MB·English

by  Goodman, Abraham Charles

THE CONSTRUCTION AND TESTING OP A CONTINUOUS EQUILIBRIUM
PLASH VAPORIZATION APPARATUS
A Thesis
Presented to
the Faculty of the Department of Chemical Engineering
The University of Southern California
In Partial Fulfillment
of the Requirements for the Degree
Master of Science in Chemical Engineering
by
Abraham Charles Goodman
June 1950
UMI Number: EP41726
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TABLE OF CONTENTS
CHAPTER PAGE
I. INTRODUCTION.................... . . . . . I
II. PREVIOUS APPARATUS ....................... 3
k
III. DESIGN AND CONSTRUCTION OF APPARATUS . . . .
Feed tanks • • • • • .................. if.
Feed pumps If
Heater......... 7
Equilibrium flash separator ....... 7
Control valves . . . . . ............... 12
Thermocouples ....... • • • • • • • • • 12
Vapor condenser and liquid cooler • • • • • 13
Receiver tanks • • • • . . ........... • 13
Miscellaneous .................. • • • • 13
IV. TEST OP APPARATUS ....................... l6
Physical tests.................... l6
Operational tests ............... . . . 17
Experimental data . . . . . . . . . . . . 21
V. RESULTS OP TEST R U N S ..................... 25
VI. OPERATING CHARACTERISTICS OP APPARATUS . . . 29
3k
VII. CONCLUSIONS..............................
LITERATURE CITED .............................. 35
APPENDIX..................................... 37
LIST OP TABLES
TABLE PAGE
I. Specific Gravity of Benzol-Toluol Mixtures . • 18
II. Experimental Data--Flash Vaporization of
Benzol-Toluol Mixtures • 23
III. Comparison of Vapor-Liquid Equilibria at
115 Pounds per Square Inch • • • • « • • • • 28
IV. Operating Log-Sheet, Run H ............. 39
V* Successive Observations at Steady State • * • • 1^.0
LIST OP FIGURES
FIGURE PAGE
1. Flow Diagram, Equilibrium Flash. Vaporization
Equipment * . .......................... 5
2. Component Parts, Equilibrium Flash Vaporization
Equipment • 6
Electrical Diagram, Equilibrium Flash
Vaporization Equipment ................ 8
Ij.* Equilibrium Flash Separator............ . . 10
5. Equilibrium Flash Separator.............. 11
6. Continuous Equilibrium Flash Vaporization
Apparatus........................... . . 1!{.
7. Specific Gravity of Benzol-Toluol Mixture
@ 25.5° c . . . . . 19
8. Temperature Curves for Run H ......... 2ij.
9* Deviation of Steady State Observations from
True Equilibrium Values................. 26
10. Thermal Efficiency of Heater ........... 32
11. Vapor-condensate Rate as a Function of
Manometer Reading ............ 33
CHAPTER I
INTRODUCTION
Vapor-liquid phase equilibrium data, at various con­
ditions of temperature and pressure, are fundamental require­
ments in the design of equipment for the separation of mater­
ials by distillation processes.
In the past, such methods as those used by Rosanoff
et al (li|) have produced satisfactory data, especially in
the case of binary mixtures. The method using the still de­
veloped by Othmer (13) was an improvement on previous methods
in that equilibrium data could be determined accurately and
did not involve any extrapolation of data; It did, however,
involve a recirculation of material. The method developed
by Stockhardt and Hull (15) eliminated the recirculation
feature of the Othmer type still, but, in doing so, intro­
duced a differential condenser hold-up leading to erroneous
equilibria where high relative volatilities were prevalent.
The recirculation feature of the Othmer type still
renders it unsuitable for mixtures which are only partially
miscible under operating conditions.
A suitable apparatus for the accurate determination
Numbers refer to bibliography, page 35♦
2
of vapor-liquid phase equilibria, for all types of mixtures,
is one in which the feed, vaporization, and take-off are con­
tinuous, namely, a continuous equilibrium flash vaporization
apparatus•
CHAPTER II
PREVIOUS APPARATUS
The continuous equilibrium flash vaporization appar­
atus introduced by Leslie and Good (10) has been used exten­
sively for vaporization at atmospheric pressure* Pancher
(4) and many others used equipment of this type*
Colburn et al (1) used a continuous apparatus in
which two pure components were separately vaporized and then
fed Into liquid in an equilibrium chamber* This apparatus
was designed for operation at low pressures only.
Nelson (12) describes apparatus, suitable for use in
vacuum and low pressure vaporizations, employing a heating
coil cast into an electrically heated aluminum block.
Penske (5) refers to continuous equilibrium vaporiza­
tion equipment utilizing Dowtherm as a heating medium*
The apparatus used by Edmister, Reidel, and Merwin
(2) employed a heating coil immersed in a lead bath which
was heated electrically. The equipment incorporated the
better features of previous equipment and, in addition, was
designed for operation at moderately high pressures. Simi­
lar apparatus was used by Edmister and Pollock (3), their
heating baths, however, being gas fired.
A critical study of the construction and operation of
these above apparatus lead to the design of the apparatus
described in Chapter III.
CHAPTER III
DESIGN AND CONSTRUCTION OP APPARATUS
The continuous equilibrium flash vaporization appar­
atus constructed contained many of the features of that used
by Edmister, Reidel, and Merwin (2)* The apparatus, a flow
diagram of which is shown in Figure 1, was designed for op­
eration at pressures between atmospheric and 375 pounds per
square inch, gauge. As constructed, the apparatus comprised
the equipment described below*
Feed Tanks:- Two seventeen gallon, vertical, cylin­
drical tanks fabricated of l6 gauge sheet steel* Each tank
was provided with a "milk-can1* type lid, a one-half inch
drain cock, a liquid-level gauge glass, a suction connection
that permitted one gallon of stagnant liquid at the tank
bottom, and four one inch angle-iron legs that raised the
tank six Inches off the ground. Details of the feed tanks
are shown on Figure 2.
Feed Pumps:- The pumps used were Hills-McCanna Pro­
portioning Pumps, Type UM-2F. The pumps each had a maximum
capacity of 7*80 gallons per hour and were equipped with
one-quarter Inch Verquad cone type check valves containing
Durimet seats and cones of Hastelloy ,fD,!* The pumps were
driven at a rate of 6JL|_ strokes per minute, through a speed