The presence of suspended particles in solutions significantly affects the crystallization rate. This study investigates the effects of calcium sulphate (crystallizing) particles and alumina (noncrystallizing) particles on calcium sulphate crystallization fouling in a plate heat exchanger. Calcium sulphate particles are formed during the preparation of calcium sulphate solution due to breakage of calcium sulphate crystals growing on the heat transfer surface. These suspended particles settle on the heat transfer surface and act as nuclei. The availability of extra nucleation sites increases the crystallization rate significantly. These particles can be removed with a filter, and the removal of the particles prevents this extra assistance available for crystallization. Therefore, the crystallization rate is reduced markedly. Alumina particles were purposely added during the preparation of calcium sulphate solutions. These particles attach loosely to the heat transfer surface compared with crystalline deposits which adhere strongly. Therefore, calcium sulphate crystals growing on these particles are removed easily. Also, alumina particles settling on the growth faces of calcium sulphate crystals may act as a distorting agent. This slows down the growth of the crystals.

Issue Section:
Heat Exchangers
Keywords:
Fouling, Heat Exchangers, Heat Transfer
Topics:
Crystallization, Heat exchangers, Heat transfer, Particulate matter
1.
Amjad
Z.
,
1988
, “
Calcium Sulphate Dihydrate (Gypsum) Scale Formation on Heat Exchangers Surfaces: The Influence of Scale Inhibitors
,”
Journal of Colloid and Interface Science
, Vol.
123
, No.
2
, pp.
523
–
536
.
2.
Bansal, B., 1994, “Crystallisation Fouling in Plate Heat Exchangers,” Ph.D. thesis, Department of Chemical and Materials Engineering, The University of Auckland, New Zealand.
3.
Bansal
B.
, and
Mu¨ller-Steinhagen
H.
,
1993
, “
Crystallisation Fouling in Plate Heat Exchangers
,”
ASME JOURNAL OF HEAT TRANSFER
, Vol.
115
, pp.
584
–
591
.
4.
Bansal, B., and Mu¨ller-Steinhagen, H., 1996, “Pressure Drop in Plate Heat Exchangers during Crystallisation Fouling,” Proceedings of the Conference of the Institution of Professional Engineers, Vol. 2, Part 2, Dunedin, New Zealand, pp. 302–307.
5.
Bott, T. R., 1981, The Fouling of Heat Exchangers, Department of Scientific and Industrial Research (DSIR), Wellington, New Zealand.
6.
Branch
C. A.
,
Mu¨ller-Steinhagen
H.
, and
Seyfried
F.
,
1991
, “
Heat Transfer to Kraft Black Liquor in Plate Heat Exchangers
,”
APPITA Journal
, Vol.
44
, No.
4
, pp.
270
–
272
.
7.
Cooper
A.
,
Suitor
J. W.
, and
Usher
J. D.
,
1980
, “
Cooling Water Fouling in Plate Heat Exchangers
,”
Heat Transfer Engineering
, Vol.
1
, No.
3
, pp.
50
–
55
.
8.
Cross, P. H., 1979, “Preventing Fouling in Plate Heat Exchangers,” Chemical Engineering, pp. 87–90.
9.
Gilmour
C. H.
,
1965
, “
No Fooling—No Fouling
,”
Chemical Engineering Progress
, Vol.
61
, No.
7
, pp.
49
–
54
.
10.
Harris, A., and Marshall, A., 1981, “The Evaluation of Scale Control Additives,” Proceedings of the Conference on Progress in the Prevention of Fouling in Industrial Plant, University of Nottingham, UK.
11.
Hasson
D.
, and
Zahavi
J.
,
1970
, “
Mechanism of Calcium Sulfate Scale Deposition on Heat Transfer Surfaces
,”
I & EC Fundamentals
, Vol.
9
, No.
1
, pp.
1
–
10
.
12.
Klima
W. F.
, and
Nancollas
G. H.
,
1981
, “
The Growth of Gypsum
,”
AIChE Symposium Series: Crystallization and Precipitation Processes
, Vol.
83
, No.
253
, pp.
23
–
30
.
13.
Krisher, A. S., 1978, “Raw Water Treatment in the CPI,” Chemical Engineering, pp. 79–98.
14.
Liu
S.
, and
Nancollas
G. H.
,
1970
, “
The Kinetics of Crystal Growth of Calcium Sulphate Dihydrate
,”
Journal of Crystal Growth
, Vol.
6
, pp.
281
–
289
.
15.
Mu¨ller-Steinhagen, H. M., 1988, “Verschmutzung von Wa¨rmeu¨bertragerfla¨chen,” 5th ed., Section OC, VDI-Wa¨rmeatlas.
16.
Mu¨ller-Steinhagen, H., 1993, “Fouling: The Ultimate Challenge for Heat Exchanger Design,” Proceedings of the Sixth International Symposium on Transport Phenomena in Thermal Engineering, Seoul, Korea, pp. 811–823.
17.
Nancollas, G. H., and Reddy, M. M., 1974, “The Kinetics of Crystallization of Scale Forming Minerals,” Society of Petroleum Engineers Journal, pp. 117–126.
18.
Novak
L.
,
1982
, “
Comparison of the Rhine River and the O¨resund Sea Water Fouling and Its Removal by Chlorination
,”
ASME JOURNAL OF HEAT TRANSFER
, Vol.
104
, pp.
663
–
669
.
19.
Schlichting, H., 1968, Boundary Layer Theory, 6th ed., McGraw-Hill Book Co., Inc., New York, pp. 596–625.
This content is only available via PDF.
Copyright © 1997
 by The American Society of Mechanical Engineers
You do not currently have access to this content.