Reuse of existing equipment for preconcentration
In many cases, existing refinery sour water strippers (SWS)
can be easily
converted to sour water concentrators. This can result in significant cost
savings by reducing the size of the two-stage WWT
plant. Not only is investment
reduced , but utility costs also are reduced because of lower steam and cooling
water consumption. The three-column approach to WWT
plant design using existing
SWS columns has been implemented successfully in three of Chevron’s own
refineries as well as in several licensee plants.
Phased construction
The WWT Process has the flexibility
to be implemented in two phases. In certain
situations this may be desired. It can be achieved by designing and installing
only the ammonia stripper column of the WWT and operating it initially as a
sour water stripper. Then, when the situation and economics dictate, it can
be integrated into a WWT plant.
The design of the plant is completed by the
addition of a hydrogen sulfide stripper, appropriate ammonia purification equipment
and other auxiliary equipment.
…for ammonia or hydrogen sulfide stripping
An existing SWS column
and its associated equipment may be used in the ammonia
or hydrogen sulfide stripping sections of the standard
WWT design. Careful
review of the SWS column
design pressure and internals together with the design
duties of reboilers, heat exchangers, condensers, etc., is essential to ensure
compatibility with WWT design requirements.