Page 8 - Treating Oilfield Emulsions

Segment I ChapterS

The Application of Heat in Treating
Petroleum Extension-The University of Texas at Austin
H eat alone does not cause an emulsion to with a bath of water, corrosion inhibitors, and, in

break down, except in rare instances. Usu­ cold climates, diethylene glycol, or antifreeze.
aUy, theapplication of heat is anauxiliary process The water bath transfersheat from the fire tube to
to speed up separation. Indeed, if at all possible, the flow-tube bundle. As cold emulsion passes
heatiseliminated entirely from thetreating proc­ through the bundle, it is in tum heated to a se­
ess. Further, in those cases where heat is neces­ lected outlet temperature. The heated water bath
sary, the heater is usually an integral part of a circulatesintheshell bymeansofa therrnosiphon
single treating vessel in which heating and treat­ effect, in which the warm water rises and thecool
ingarebothaccomplished. Because separate heat­ water falls to be reheated by the fire tube. The fire
ers are sometimes employed in treating systems tube and flow-tube bundle are removable for
on certain leases, and because the operation of easy cleaning, inspection, and replacement.
separate heaters is applicable to the operation of Since the flow tube is subject to corrosion both
heaters combined with treating vessels, itisworth from the emulsion flowing inside itand from the
studying them. water bath surroundingit, the returnbendsin the

INLET

Figure 20. An indirect heater

Indirect Heaters flow tube are safety drilled, that is, a small hole on
the outside of each bend is drilled about halfway
While a few direct heaters are still in use where
separate heaters are employed, far and away the through the metal of the tube where corrosion
forces are most concentrated (fig. 21). When cor­
mostcommonlypeofheater is the indirect heater.
Unlike direct heaters, in which emulsion is put rosion erodes through a safety drilling-about
into direct contact with fire tubes, indirect heaters half of the flow tube's thickn~mulsion will
are constructed so that a hot water bath transfers leak through the corroded safety drilling and into
its heat to the emulsion. the water bath. An alert operator will be able to
An indirect heater consists of three main parts: see the leaking emulsion in the water bath and
(1) the shell; (2) the flow-tube bundle; and (3) the know that repair is required before continuingto
fire tube (fig. 20). In operation, the shell is filled operate the heater.

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