Reverse Osmosis Pumps and ERDs The Right Choice for Offshore Platforms and Marine Service - White Paper - FEDCO
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White Paper
Reverse Osmosis Pumps and ERDs
The Right Choice for Offshore
Platforms and Marine Service
MK-WP-02
Fluid Equipment Development Company, LLC www.fedco-usa.com
Offices in USA, Singapore and Dubai sales@fedco-usa.com
Reverse Osmosis Pumps and ERDs The Right Choice for Off-shore Platforms and Marine Service
Executive Summary tems to produce low TDS (total dissolved solids) water
for potable needs, process equipment requirements and
Reverse Osmosis (RO) systems are widely accepted on
high volumes for enhanced oil recovery.
offshore platform and vessels. These marine applica-
tions require compact size, good efficiency and low
The high-pressure pump is literally the heart of the
weight and the utmost in reliability as a failure can
RO system. Pump reliability is best obtained through
result in large economic losses.
simplicity of design, minimal number of moving parts,
The high-pressure feed pump (HP pump) in the RO tolerance to upset conditions and misoperation and
system pressurizes feed flow to the membrane array to minimal maintenance requirements.
drive the separation process. This pump is mission-crit-
ical yet has the challenging task of pressurizing a corro- Likewise, the ERD must display the same beneficial
sive fluid to high pressures using close-clearance parts characteristics to justify its presence in a marine ap-
rotating at high speed. plication. The following factors figure prominently in
selection of the HP pump and ERD.
The hydraulic energy in high pressure brine can be
recovered with an Energy Recovery Device (ERD) to Size – The most expensive real estate in the world is
reduce the net energy consumed by the RO system. not in Dubai, London, Tokyo, or New York City – it is on
Energy savings is certainly a positive factor yet the ERD marine vessels and offshore platforms.
must bring other benefits to the marine environment
that offsets the added complexity and cost. Weight – Each pound of machinery requires three to
five pounds of platform weight1.
FEDCO also developed and manufactures several lines of
centrifugal multistage pumps specifically for RO service Reliability – Seafaring RO systems require the ut-
with hundreds of marine installations to date. Key fea- most in reliable components and most notably in the
tures include Super Duplex SS (PREN>40) construction, high-pressure pump and energy recovery device. Down-
compact size, low noise and vibration and advanced time can have a devastating economic impact.
bearing technology for maintenance-free operation.
Efficiency – Good efficiency reduces the size, weight
FEDCO also developed and manufactures the Hydraulic and capital cost of the power supply in marine applica-
Pressure Booster or HPB Series ERD turbocharger. This tions.
product line compliments FEDCO pumps with the same
material of construction, compact size, advanced bear- Experience – An offshore platform is no place to test
ing technology and maintenance-free operation. untried equipment.
Together, FEDCO HP pumps and the FEDCO HPB tur- Pump and ERD Options
bocharger represent the preferred package as proven Let’s take a look at positive displacement (PD) HP
in hundreds marine installations in platforms, fishing feed pumps. These pumps fall into two major types;
vessels, factory ships, cruise liners and military vessels. power pumps (crank/crosshead drive) or axial piston
With a feed capacity range from 6 to 1,100 m3/h for (AP) pumps (swash plate drive). PD pumps have good
HP pumps and turbos up to 3,200 m3/h, provides the efficiency, however, fail to achieve the requisite reliabil-
optimal solution for marine RO systems. ity due to high number of parts (multiple valves, and
drive-end components) and extremely tight operating
Introduction clearances creating a high susceptibility to damage
Increasing numbers of offshore platforms and marine from even minor amounts of debris. Some AP pumps re-
vessels rely on seawater reverse osmosis (SWRO) sys- quire a filtration level of 5 microns absolute achievable
Fluid Equipment Development Company, LLC www.fedco-usa.com
Offices in USA, Singapore and Dubai sales@fedco-usa.com
Reverse Osmosis Pumps and ERDs The Right Choice for Off-shore Platforms and Marine Service
only with multiple specialized filters placed in series. nals with flows from 15 to 260 m3/h and pressures to
Moreover, annual overhauls are required that are best 70 bar.
performed at factory-authorized facilities.
SSD Series Centrifugal Pump – Single stage with ∆P
PD pumps have been known for limited capacity, gener- to 35 bar used with the turbo. Construction in Super
ate potentially damaging flow and pressure pulsations Duplex SS with flows to 1,100 m3/h.
and often require gear boxes or belt drives to match
driver and pump shaft speed requirements. SLP Series Centrifugal Pump – low pressure feed pump
in Super Duplex SS used for pretreatment and backwash
In contrast, centrifugal pumps generate smooth flow, with flows to 180 m3/h up to 12 bar differential pressure.
have low vibration and can operate directly coupled to
the driver. Please refer to Figure 2 for approximate hydraulic coverage.
The FEDCO HP pump line was designed for one market,
seawater desalination. This pump line is offered in Su-
per Duplex SS, Duplex and 316 SS. Pressure differential
range is from 10 bar to 100 bar with flow rates from 20
to 1,100 m3/h. Other features critical to reliable RO ser-
vice includes elimination of oil/grease lubrication (and
associated failure modes), low shaft sealing pressure,
isolation of the motor from pump axial thrust loads and
good efficiency and, most importantly, the patented
Water Bearing™ technology.
Figure 2 Approximate hydraulic coverage of FEDCO pumps and
turbos
A Little About the Water Bearing™
HPPs generate many thousands of pounds of axial
thrust. Absorbing that thrust challenges conventional
oil/grease lubricated bearings – lubrication failure, loss
of lubricant, excessive heat, contamination by dirt or
water and sustained off-design operation often result in
Figure 1 Land based real estate is not as expensive as an off-
shore platform per ft2
accelerated wear if not catastrophic failure. The pat-
ented FEDCO Water Bearing™ absorbs the thrust load
MSD Series Centrifugal Pump – The premium pump using force balance using only feed water pressure – no
line for severe service uses precision cast electropol- oil, no grease, no lubrication failure. Several thousand
ished components with a highly optimized flow path for pumps use the FEDCO Water Bearing™.
industry-leading efficiency of up to 86%. Hydraulic cov-
erage is from 20 to 850 m3/h and pressures to 80 bar. Please refer to Figure 3 for more information.
MSS Series Centrifugal Pump – Construction in Duplex
SS and 316 SS (electropolished and passivated) inter-
Fluid Equipment Development Company, LLC www.fedco-usa.com
Offices in USA, Singapore and Dubai sales@fedco-usa.com
Reverse Osmosis Pumps and ERDs The Right Choice for Off-shore Platforms and Marine Service
Water BearingTM Technology Analogous to a turbocharged diesel engine, a turbo-
FEDCO - Shaft in Tension maintains straightness charger in a RO system uses high pressure brine (“ex-
haust”) to pressurize the incoming feed water. The tur-
• Straighter shaft reduces rubbing agains shaft journal bearings
bo is placed between the discharge of the HPP and the
• Location of the Water BearingTM places the shaft in tension
membrane array. A turbo can provide up to 50% of the
Motor Journal feed pressure with the HP pump providing the balance.
bearing Please refer to Figure 5.
The turbo automatically reacts to the feed and brine
flows to produce a pressure boost. System control is
accomplished by adjusting a brine control valve integral
FEDCO Water BearingTM with the turbo.
Note that turbos reduce the size of the feed pump and
Conventional Shaft in Compression - bends the shaft motor by reducing discharge pressure and motor input
• Increases potential for shaft bending or bowing power. The motor starter or VFD, cabling and generator
• Increases potential for friction with shaft bearing and impel- capacity are similarly reduced. The weight savings pro-
ler wear rings vided by the HPB turbo exceeds its own weight by many
times over. A corresponding reduction in equipment
footprint is likewise achieved.
Potential An HPB-10 (Figure 6), suitable for flow rates up to 11
Conventional thrust bearing rubbing m3/h, weighs only 10 pounds. An HPB-2800 suitable for
(in motor or external housing) 3,000 m3/h of feed flow weighs about 67,545 pounds.
Note that the HPB requires no additional equipment,
Figure 3 Water BearingTM
instrumentation or valves. And the HPB can be located
anywhere in the RO system to reduce piping costs and
improve accessibility.
A Little About Turbochargers
Recovery of the hydraulic energy in the RO brine stream
to reduce net energy consumption is widespread on
land-based systems using several types of ERDs. How-
ever, ERDs on critical applications such as marine and
military RO systems have been largely limited to just
turbochargers.
Figure 5 HPB in RO system
HPB-10 - Feed flows
as low as 6 m3/h
Figure 4 FEDCO ship based system Figure 6 HPB-10
Fluid Equipment Development Company, LLC www.fedco-usa.com
Offices in USA, Singapore and Dubai sales@fedco-usa.com
Reverse Osmosis Pumps and ERDs The Right Choice for Off-shore Platforms and Marine Service
Packaged Systems
The FEDCO marine package includes low pressure pumps,
three types of high-pressure feed pumps (MSD, MSS or
SSD depending on the specific user requirements) with
FEDCO turbos. The turbo provides up to 45% of the feed
pressure and is entirely driven by the high pressure
concentrate stream. Noteworthy features of the marine
package include:
• Zero-maintenance;
• No oil or grease lubrications, water-lubricated bear-
ings (excluding motors);
• No ambient temperature limits; Figure 8 HPB-2800 Turbo in a 330,000 m3/day SWRO facility on
• Quiet and smooth operation; the Arabian Gulf
• Highest energy efficiency; Figure 8 shows a FEDCO SSD-500 single stage HP pump
• Longest warranty in the RO market. and an HPB-500 turbocharger with an exceptionally
small footprint in a 5,000 m3/day seawater RO system
permeate output system (shore based). This system has
operated near continuously for 5 years with 100% avail-
ability and zero-downtime. Specific energy consumption
is typically 2.4 kWh/m3 of permeate.
Pump
Turbo
Figure 7 Offshore platform installation
The FEDCO HP Pump + HPB, used in hundreds of marine
and military SWRO systems, has achieved unmatched
acceptance. Figure 10 show one of several hundred mili-
tary RO systems using an MSS pump and HPB turbo.
Mega Scale RO Systems Figure 9 FEDCO HPP and Turbo for a 5,000 m3/day RO train
Enhanced oil recovery technologies require high vol-
umes of water with a low level of Total Dissolved Solids High Recovery RO
(TDS). RO can provide the requisite TDS level, but High recovery represents perhaps the last significant
limited platform space and weight constraints are a process improvement in seawater RO desalination.
challenge. FEDCO offers a high recovery seawater RO configuration
that permits permeate recoveries of 60%. Two (2) mem-
Fluid Equipment Development Company, LLC www.fedco-usa.com
Offices in USA, Singapore and Dubai sales@fedco-usa.com
Reverse Osmosis Pumps and ERDs The Right Choice for Off-shore Platforms and Marine Service
brane stages in a brine stage configuration use inter-
stage boost provided by a turbo. Membrane flux balance
is improved, and fouling potential is reduced compared
with single stage systems. Higher recovery also reduces
the size of the pretreatment system as well as chemical
consumption.
Figure 10 Military SWRO system
About FEDCO
Founded in 1997 as a pump and ERD development partnership with a large RO system builder, Fluid Equipment Devel-
opment Company, LLC, evolved to a vertically integrated design, manufacturing and global sales/marketing company.
FEDCO holds numerous patents in pump and turbine design and reverse osmosis system design. FEDCO is a privately held
company with a proven commitment to its customers, suppliers, end users, its community and the environment.
Manufacturing and Head Office - Monroe Michigan U.S.A.
Fluid Equipment Development Company, LLC www.fedco-usa.com
Offices in USA, Singapore and Dubai sales@fedco-usa.com
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