paraffin wax deposition and fouling

— 17
—
a deporsiion ce:Ll in a circulation loop as developed by Cole and
(7!)
;ecsen - The chilled dpcsition plate was made of polished
utainless L3teei
The solution used was a l.5 pcr cent weiht
melting point refined wax in commcrcial grase n—hetane.
0
The solution was maintained ac 2tt C
ann clrcujatea tarougi. te
deposition cell at the rate of 1.06 cm/S waich corresponcied to
a laminar flow velocity of 24 cm/s over the deposition surface.
The solution cloud point was 2200 and the deposition plate was
maintained at 19°C.
Ipon completion of a test run the deposition
plate was removed and turned on edge to drain.
Any Dart of the
deposit which slid off was caught in an evaorating disn along
wita any iquin that aratnec :rom tne aeposat.
The remaining
ne:Doslt was wasned off wica n—neutane anc. caugac ifl a separate
dish
These were recorded as the total deposit and the adhere
detosit respectively.
See fig. 2.3.3.2 where adhered and total
deposit are plotted as a function of time.
:t ‘ias determined definitely by Patton and Jessen that the
acnerec. c.eposat was atcacnem to tae suriace.
The ouer port:on
of tne cieposat wr ach immeaiatey sougaea was a resu_t of tne
orerational crocedure.
Then the flow of paraffin solution through
the cell was halted at the end of each test, the cell was full of
stagnant raraffin solution for a few seconds prior to draining the
cell.
During this brief period, the rortion of the fluid adjacent
to tae decosat was coclen seow its cloum POiflt ann tae precaci atea
wax rartices :ornea a seconnary c.erosa; on too o: tne org:na_ one.
This secondary denosit as not the result of a crystalline growth
process but rather a quickly chilled zoortion of the fluid which
formed a gei. structure of annavaciua wax partac_es. ure
threshold ceriod in fig. 2.5.3.2 was thought to indicate that a
curtain amount of tine was necessary for the denosit to develor a
recuired minimum cohesive strength.
De-cosits become increasintly