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The World’s
Highest-Pressure
Injection Pump
PAUL MEUTER
SULZER PUMPS
As oil exploration moves further offshore into deeper
water, the oil reservoir pressures increase far beyond
those experienced in the past. Therefore, injection
pumps used to support the oil reservoir pressure
need injection pressures far above the technology of
existing centrifugal pump designs. Sulzer Pumps has
trodden new paths – and developed the world’s
highest-pressure centrifugal injection pump.
The exploration of deep-
water oil fields requires injec-
tion pumps with extremely high
pumping heads (Fig. 1). Oil com-
panies have selected several pump
companies to develop designs to
meet their tough demands. This
gives them the opportunity to par-
ticipate and review the designs
and manufacturing processes
thoroughly, to address interfaces
to the other equipment and assess
risks in an early phase. Robust, re-
liable pump designs as well as
safety of the operating personnel
and production facility are of high
priority.
Based on Experienced Designs
The very high pumping head – up
to 5600 m or 580 bar – demon-
strates the biggest challenge. In
order to minimize risk, the pump
selection criteria such as hy-
draulics, speed, head per stage,
number of stages, and design pres-
10
SULZER TECHNICAL REVIEW 4/2002
4072
sure should not deviate too much
from the designer’s experience
wherever possible.
Typically, the existing hydraulics
for multistage pumps, consisting
of impellers and diffusers, need a
larger shaft to transmit the high
power. This is a relatively small
design change, but nevertheless,
the altered hydraulics have to be
model-tested for validation of
their performance.
Speeds of rotation not higher than
6000 rpm are common. The gener-
ated head per stage is to be limited
to about 600 m, ensuring accept-
able erosion rates for the super
duplex stainless steel and hence
achieving long operational life for
the pump parts.
The combination of number of
stages, type and size of the hy-
draulics, and speed determines the
rotordynamics of the pump, which
can only be analyzed after the
pump rotor has been designed. A
detailed rotordynamic analysis is
of great importance to demon-
strate that the eigenfrequencies
have enough separation from the
operating frequencies and that the
damping is high enough, even
with worn internal running clear-
ances, hence ensuring smooth run-
ning of the pumps at all operating
conditions in the field.
After the selection of the pump, a
plan has to be established address-
ing how the features that are be-
yond the manufacturers experi-
ence are handled to minimize risk.
One area of concern on all the ul-
tra-high-pressure pump designs
are the static seals to keep the
joints of the pressure-retaining
parts tight during operation and
during hydrostatic pressure test.
Detailed finite-element calcula-
tions have to be conducted to de-
1
The range chart of
type HPcp injection
pumps could be
expanded with the
development of ultra-
high-pressure injection
pumps covering a
pumping head up to
6000 m.
6000
5000
4000
3000
2000
1000
0
0
1000
2000
3000
4000
Flow (m
3
/h)
Back-to-back design with bolted delivery cover
In-line design with bolted delivery cover
In-line design with Twistlock delivery cover
(Twistlock allows for a quick cartridge exchange, see STR 2/2000, p. 18)
Installed pumps
Ultra-high-pressure
injection pumps
termine the maximum stresses and
deformations. Furthermore, the
static seals are to be tested in a
test rig.
The in-line design is the classical
concept used on most high-power
multistage pumps either for injec-
tion or boiler feed services. A bal-
ance drum installed after the last
stage reduces the axial hydraulic
thrust to the capacity of the dou-
ble acting thrust bearing. Normal-
ly, mechanical seals seal the suc-
tion pressure to atmosphere. Pres-
sure oil feed journal and thrust
bearings align the rotor to the
Two Different Designs
Sulzer Pumps offers two pump de-
signs (Fig. 2):
Impellers arranged in-line for
higher flows
Impellers arranged back-to-
back for lower flows
2
Two designs of
ultra-high-pressure
injection pumps are
available. With the
impellers arranged
in-line (top), the drive
power may reach up
to 34 MW. With the
impellers arranged
back-to-back (bottom),
a pumping head up to
6000 m is possible.
SULZER TECHNICAL REVIEW 4/2002
11
3D modeling techniques and ana-
lyzing tools. Figure 4 shows the
typical deformation at operating
condition presented in an exagger-
ated view. With this analysis it can
be proven that a positive surface
pressure at the inside of the bolt-
ing near the o-ring groove can be
maintained, thus eliminating any
possible o-ring extrusion at all op-
erating conditions.
For safety reasons the suction
casing has to be sealed to the at-
mosphere for the full discharge
pressure if there is no pressure re-
lief system installed in the suction
pipe. Only a radially arranged
sealing system is feasible by de-
sign. With rising pressure the radi-
al extrusion gap increases. A seal-
ing system for this purpose con-
sists of a tough, resilient, T-shaped
ring with a pressure-actuated anti-
extrusion ring used in the aero-
nautical industry. For the first
ultra-high-pressure pump a test
rig which reproduced this radial
gap under this high pressure was
built for testing the sealing system
prior to pump manufacture. The
tests were successful and con-
firmed that the suction end sealing
system was fit for purpose.
3
Barrel casing
with bolts.
When using high
pressures, special
attention has to
be paid to the
sealing of the
delivery cover.
Analysis of Critical Components
Components and features critical
to reliability and safety have been
identified for detailed investiga-
tion during the design process.
Here, only two parts of the many
analyzed are described.
The delivery (or discharge) cov-
er (Fig. 3) closing the barrel casing
to atmosphere is sealed with a face
o-ring. This seal is only tight if
full metal-to-metal contact can be
maintained. To prove this, a finite-
element calculation has been per-
formed, utilizing state-of-the-art
stationary casing. The pump
features a full pull-out cartridge,
allowing for a quick exchange of
the cartridge.
The back-to-back design balances
the thrust itself to a large extent.
Thus, a smaller thrust bearing can
be used. The center and the
throttle bushings are only subject-
ed to half the pump pressure and
act as Lomakin type bearings. This
design is especially suited for ultra
high pressure at low flow. All
other features are the same as for
the in-line design.
Protection Against Sand Wear
Injection pumps must be capable
of handling sand, especially if
produced water is pumped. The
components forming the close run-
ning clearances have to be protect-
ed by using newly developed
HVOF coatings or wear parts with
solid tungsten carbide inserts (see
STR 1/2001, p. 22).
4
The deflections of the bolted deliv-
ery cover connection at operating
condition has been analyzed utilizing
state-of-the-art 3D modeling and
finite-element analysis tools.
Barrel casing
Delivery cover
Nut
Bolt
Highest Pressure in the World
For the BP Thunder Horse project
in the Gulf of Mexico, Sulzer
Pumps has participated in a devel-
12
SULZER TECHNICAL REVIEW 4/2002
opment competition and, in 2001,
was awarded the manufacturing
and testing of the prototype injec-
tion pump with the highest pres-
sure in the world. The pump had
to generate a head of over 5600 m,
turned at 6000 rpm and was driv-
en through a gearbox with a
10-MW variable-frequency drive
motor. The selected pump was of
the back-to-back design and had
12 stages. The material of con-
struction was super duplex stain-
less steel with high strength and
corrosion resistance.
The pump was vital to the cus-
tomers’ project success. Since a
pump with such high pressure had
never been built before, a proto-
type pump was manufactured and
extensively tested. The hydrostatic
pressure test had to be conducted
under severe safety precautions.
The pump test assembly was set
up in a pit not accessible to the
test personnel. The pressure was
increased incrementally up to
957 bar (65% higher than the re-
quired operation pressure) and
successfully held at that pressure
for 30 min.
The predicted hydraulic perform-
ance was confirmed with the per-
formance test conducted at full
speed at the Sulzer Pumps test
facility in Leeds (UK). The cus-
tomer’s requirements including
the standards of API 610, 8th edi-
tion, could be met.
Rotordynamic tests were carried
out running the pump at full speed
and full load (Fig. 5) with two
times new running clearances sim-
ulating end-of-life condition. The
stiffness gained with close running
clearances is reduced with large
clearances, thus vibration is ex-
pected to be higher. Hardly any
change of the low vibration level
was detected between the tests
with new and worn running clear-
ances. Vibration levels were all
within the limits set out in API 610
across the full operating range. In
addition, unbalance was added to
the coupling to check the rotor sen-
sitivity. The measured vibration
amplitude was below the predict-
ed value.
All test results fulfilled the cus-
tomer’s requirements and demon-
strated that the pump is robust
even with end-of-life running
clearances. The customer then re-
leased an order for three addition-
al complete pump units.
This new and innovative develop-
ment of ultra-high-pressure injec-
tion pumps allowed Sulzer Pumps
to extend its range of pumps in or-
der to meet even more challenging
demands in the future.
CONTACT
Sulzer Pumps (UK) Ltd
Tony Waterfield
Manor Mill Lane
GB-Leeds LS11 8BR
Great Britain
Phone +44 (0)113-272 44 18
Fax +44 (0)113-272 44 84
E-mail tony.waterfield@sulzer.com
5
A Thunder Horse injection pump unit mounted on a massive skid – destined for BP’s deep-water
field development in the Gulf of Mexico – is ready for a full-speed, full-load string test with all its aux-
iliary equipment and instrumentation in the Sulzer Pumps manufacturing facility in Leeds (UK).
SULZER TECHNICAL REVIEW 4/2002
13
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