paraffin wax deposition and fouling

—5—
vary from less than 1 per cent to more than 30 per denonstrat—
ing clearly the range of problems encountered.
2.2.1 Petroleum
a:es
The
technology and Properties of petroleum waxes have been
reviewed extensively in several references
-
V
Petroleum waxes can in general be divided into paraffin and
microcrystalline waxes.
Paraffin waxes are obtained from
distills
:ion of petroleum at
300—460°c and microcrystalline waves at higher temperatures.
Paraffin
waxes are available in various stages of refinement like siack wax,
yellow crude scale, white crude scale or semi refined wax and then
fully refined wax.
Paraffin waxes consist mainly of normal :Darafns
015 to C with small proportions of branched paraffins and have
meting potnts from
0
-, o_,
to 70 L.
Microcrystalline waxes are seldom available with the same 10;
range of oil contents as refined paraffin waxes.
They are apt to
deposit from waxy crudes during production (rod waxes), transror;ation
(ripeline waxes) and storage (tank bottom waxes).
Microcrystalline
waxes contain higher proportions of branched paraffins than raraffin
waxes, together with long side chains which interfere with the growth
of large crystals.
Microcrystalline waxes have melting points from
60 to 90°C.
2.2.2 Crystallization
Rnones et
a
(20)
ootainea two
tyes o
paraf:zn wax crysta_s,
needles and plates, the relative amounts of which are determined by
the conditions under whi-ch
crystallization is effected.
:ere
was
no indication chat the two crystal tymes represented different
alle;rcric modifications of paraffin wax so they were consincrei as
b.:o cr:rct hallcs of the saae solid phase.
:t
.cur-. chat
neec_es are no; ;rce snag_c cr:s;a±s but are comorasea o_
OIca.
aggregates
ormea by the curling of the
rates.