paraffin wax deposition and fouling

the major unresolved problem in heat transfer
8. In spite of
increases capital and operating costs of transfer equipment.
transfer surfaces. It reduces heat transfer coefficients and
ouling is tne deositon of undesirable substances on heat
1.1 Foulinç in General
Though being well known, fouling is poorly understood and remains
1. ITP3DUCTlON
ing resistances and are caiie fouling factors anc are casea
are obtained from design correlations but R (tube wail) from the
specified. The resistances R. (inside tube) and (outside tube)
shut down and cleaning costs.
Operating costs result from increased pressure drops and excessive
Capital costs of transfer equipment increase due to fouling
in industry make most fouling situations unique, rendering
coefficients. The vast range of process streams and conditions
—1—
advances in heat transfer in the past decades, fouling continues
to negate any improved methods of evaluating heat transfer
comprehensive understanding difficult.
1.2 Effeccs of ‘ouling
be cause extra heat transfer area is required for the same duty.
The heat transfer area of an exchanger can be determined from
a relation of the form:
A = -4’ (R. + R + R + . + i ) ..... (.2)
1 0 w
The transfer rate and mean temerature difference T are usually
m
therma conauc;vzty o± tuce material and its thic.mess. The Iou—
on previous ererience. They are the designers safety factors
amc
•. (i)
account zor :oL.ing ama rougnness o transzer suraces .
The extra surface area required, due to fouling can be quite
tme aesn oz excman;ers’ This area mas ocen