Page 223 - Petroleum and Gas Field Processing

Figure 3 Main functions of vapor recovery system.

not only cause a loss of income due to loss of hydrocarbon volume and
change in the API of the oil but will also lead to pollution and fire
hazards.
The three main functions for the vapor recovery system are (as
illustrated in Fig. 3) as follows:
1. To collect vapor from storage/loading facilities
2. To reliquefy vapors
3. To return liquid hydrocarbons to storage
Basically, when we talk about a VRU, what we are looking for is to
hook our storage tanks to a ‘‘breather’’ system such as the following:
During the day, when the temperature rises and vaporization of
the hydrocarbons occur, excess vapors can be released and
collected by the VRU.
At night, when the vapors cool and condensation takes place
leading to partial vacuum, vapors from the VRU will be admitted
into the tanks.
While pumping in and pumping out liquids to and from the
storage tanks, vapors could be vented, [i.e., collected and drawn
in, respectively, by such a breather system (VRU)].

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