paraffin wax deposition and fouling

— -ii
—
deposit.
Tronov statej thal scudies on paraffin deposition ineicate that
the ouilc—up 0±
cposits alternates wtn their partial or total
removaa,
lndepenoenL of tne nature
o
the suriace.
ior e:a:nple,
it
has been observed that deposits are removed from a glass surface in
large lumps ieaving the surface very clean.
fronov considers that removal of deposits from pipe walls
governed by a lifting force acting at right angles to the direction
of flow, and a shearing force acting in the direction of flow.
The
transport of removed particles or lumps, away from the surface, is
then effected by the increase in fluid shearing in the radial direc
tion, •mnich is also responsible for keeping the paraffin ‘ax Partc_es
an susuension.
:t
should be noted that Tronov ony consaderec. c.erosi—
ton
in the lamInar flow region.
The idea of a
lfting
force
effectang removal of deposats mas not arearem an tne avaaao_e
literature before and therefore Tronov’ s arguments wiil now ‘cc
considered.
Paraffin deposits being porous, means that the oil not only flows
in the pice centre, but also in the mass of the deposits. The Thow
velocity above the deposits will be
considerably higher than inside
it,
leadins to a lifting force proportional to velocity scuare, as
in aerodynamics and river oem aeveLopment. The
fting
aiim snearang
forces wi
of the lump
act samu._taneous_y ifl ratios cerenciang on ;ne oraentataon
ceing removec..
Jthough no
information was found in the literature on the roro—
sity of raxaffin derosit,
it
was considered unlikely that ror.ov s
conce;:on o: a a:tzrg torce cou._m cc true.
accon nan Oasaci
staten mat :or a gaven tame reraom tnc
altount of paraffin derosited in a cold srot tester decreased as the
stirring rate increased.
:,
considering the cold spot tester as a