It takes a lot
of water to run a refinery and even more to start up a cold
one. Charles McCloskey
A major US East Coast refinery recently started up after a
lengthy shutdown and overhaul. The refinery needed assistance
in restoring the purified water flow to the facility. Engineers
were called on to inspect and recommend repairs and upgrades to
critical components such as the raw water clarifiers, filters
and demineralization systems. The refinery was provided with a mobile
reverse osmosis (RO) treatment system to furnish up to 1,500
gallons per minute of boiler feedwater required to restart
Water is a critical component of the refining process, with an estimated
80 gallons of water required per barrel of oil converted. Steam
is used extensively for process heating and fractionation.
Copious amounts of cooling water are used in heat exchangers to
condense the valuable end products of the refining process. Additional water
is required for onsite electricity generation to power the
facility. A cold startup of process units is very
water-intensive, as returned condensate can be significantly
lower, intermittent and of unreliable quality, compared to
normal steady-state operations.
From idle to online.
When new owners decided to bring the idle East Coast
refinery back online to meet rising market demand, water was
one of the first concerns addressed by the management team. To
meet the aggressive schedule for returning the plant to
profitable production levels, the refinerys engineering
team needed assistance. To illustrate what the refinery was
looking at, as far as infrastructure goes, Fig. 1 shows the
basic design of the plants water treatment system.
Fig. 1. Basic design of
plants water treatment system.
Water for this refinery is available from multiple sources
including wells, surface water and municipal supply (Table 1).
Pretreatment is generally required for most waters to remove
suspended solids and turbidity before further purification for
process water and steam production. The first step to restoring
full water flow, therefore, was a detailed engineering review
of the pretreatment system.
The pretreatment system was originally designed to deliver
3,160 gpm and consisted of one cascade aerator, one flash mixer
(7 ft square and 7.5 ft deep), two precipitators (each 38 ft
square and 16 ft deep) and four gravity filters (each 18.51 ft
wide, 21.33 ft long and 13 ft deep).
As might be expected, the equipment had undergone
significant modifications over the past 55 years of operation.
An evaluation team detailed the condition of the equipment and
alterations in the engineering report, and provided
recommendations to replace critical components. The team also
reviewed operations with onsite personnel and provided
suggestions to improve the efficiency, consistency and reliability of the pretreatment
system. A crucial component of the evaluation was that a
complete set of original equipment drawings were recovered and
presented to the new operators and engineering staff. The major
conclusion of the study was that, while the system had aged, it
was in serviceable condition to produce the design flow rate of
3,160 gpm. By following the recommendations, the useful life of
the equipment could be even further extended.
While plant personnel worked on the pretreatment system to
implement the necessary changes, the timetable for the refinery restart required that at
least 50% of the estimated 3,000 gpm of purified water be
supplied in short order. The refinery contracted with an
outside company to provide up to 1,500 gpm of treated water for
boiler makeup to begin steam production.
The temporary water system consisted of the following key
Three bag filtration skids. Each
skid was rated for 1,000 gpm. Bag filtration using 10-micron
bags provided an added layer of protection against turbidity
Four anti-scalant feed systems.
Each RO trailer had its own dedicated anti-scalant feed
Cartridge filtration. Cartridge
filters were provided as a final filtration step prior to the
RO units. Each RO unit had a housing that contained 12 30-in.
16 RO units. Each unit had a
3:2:1-4M array and 24 8-in. x 40-in. RO membranes. The unit was
capable of delivering up to 100 gpm of RO permeate at 16.4 GFD
flux and 75% recovery at a temperature of 40°F. Each unit
had online feed and permeate conductivity monitoring, as well
as permeate and concentrate flow indicators.
Four membrane separation trailers
(MSTs). Each MST housed four RO units, and provided
interconnecting piping, electrical distribution, lighting and
Four mobile deionization (DI)
trailers. Each trailer consisted of two cation and
three anion exchange vessels, each containing 90 ft3
of resin, and one mixed bed vessel containing 60 ft3
Within days of the go-ahead, the temporary system was up and
delivering the desired water quality to the refinerys
power island. The system has operated without interruption for
the past six months, consistently meeting the water quality
specifications (Table 2). These are critical parameters for
safe operation of the onsite 1,300-psig boilers.
The next step was to restore the onsite demineralizer
systems to full production capacity. Two systems are onsite: an
older conventional design and a newer packed-bed system. Resin
analyses indicated that significant fouling of the anion resin
had occurred over time. An onsite resin cleaning service was
employed to restore the capacity. Vessels were inspected, and
linings and laterals were replaced as needed. Most of the
cation resin was purchased and replaced. The contractor
provided the engineering resources, parts and contract labor to
support this effort. The contractor also provided tankering
service to remove, separate and reload the resin while these
tasks were completed. Work continues in this area to bring the
water system up to full capacity.
Working with water treatment suppliers has enabled this refinery to go from cold to hot with
nearly full water and steam production while ramping up its refining capacity. HP
flow for maximum recovery.
| RO trailers
are fully instrumented for efficient
operating contracts include all
labor, chemicals and consumables.
Charles (Chuck) McCloskey is the
director of business development for mobile and onsite
services for Siemens Industry, Inc. Mr. McCloskey is a
graduate of Slippery Rock University of Pennsylvania,
and has been actively involved with industrial water
treatment applications for the past 34 years. He is
located in Hoffman Estates, Illinois.