paraffin wax deposition and fouling

-.9—
whica is well novc conditions existing in tubes and pipes carr’fint
Para’fin waxco dissolved in hy:ccarbon solvents.
t has been found that in laminar flow small particles carL
migrate across
th
planes of shear.
In turbulent pipe flow a particle
placed in the laminar boundary layer will therefore move away from
the wall to settle at the limit of the boundary(2S
It has in fact
been shon by a laser—doppler anemometer that there is a ccncerLtra—
tion gradient set up within a laminar susrension boundary
ayer(29).
d particle iiich has sufficient momentum to enter the boundary layer
may therefore exacrience difficulty in let alone adhering to the wall.
2.3 Factors ffectin,g Paraffin Deposition
The
first
attempts to evaluate the raraffin derosition rrobem
1nvovea the exam:naton of cruc.es sy use of vascosaty—temnerature
curves and chromatography.
More recently important factors
effect
ing paraffin decosition have been identified, such as surface pro-Der—
ties ann ancitaves.
2.3.
F.owrate
essen ann
3
owen
stuacen tne ef:ect of
ioxate
on
ra:in
derosition in stee:. and rlas;ic coated steel pipes; their arparatus
consisted of 0.75 inch :Dipe 5
ft.
long submerged in a cold water bath.
From a 30 gallon reservoir, in a hot water bath, microcrystalline wax
in keroser.e solutions and several crude OilS were circulaten far acout
3 hours.
:
all the runs tac solution bulk temperature was kant below
its
cloud roint.
The wax derosited was removed mechanically from the
pire which was then washed wita normal penoane. The amount of wax
aeposat was tner. cetermarn cy separatIon :rom tne pencame in a
centrifuge.
The main conclusion of the ‘‘ork was that in laminar flow.
dprosition increasea with flowrate, reacn:n; a maximum rrnor to tranaa—
tion to turbuenn Z.ow ama ;nen decreasin: with increasin turbulence.
The
increase in arosi:ion, in laminar flow, with increased
florate,