Page 173 - Petroleum and Gas Field Processing

Figure 16 Chemical injection: upstream of the level control valve of the gas–oil
separator.
would lead to what is known as ‘‘burning of the emulsion’’ (i.e.,
unbreakable or tight emulsion).

5.6 ELECTRICAL AID

This is the third aid of emulsion treating in crude oil dehydration.
However, it should be realized that both heating and chemical treating
work in order to ‘‘break the emulsion’’, whereas electrical emulsion
treating is aimed at speeding up ‘‘coalescence,’’ hence settling. In other
words, electric dehydration does not break the emulsion electrically.
Looking at the three consecutive steps involved in the dehydration of
emulsified crude oils (breaking the emulsion, coalescence of water droplets,
and settling and separation) and assuming that the first and third steps are
fast compared to the second step, it can be concluded that coalescence is
the controlling step. In other words, coalescence, which is a function of
time, influences settling. Consequently, in the design of dehydrators, some
means should be implemented to reduce the coalescence time, hence the
settling time. Some of these means are (1) installing a coalescing medium

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.