Cay Bay Plant - Seven Seas Water

A Green Future:
Developing
p g Caribbean Water and Waste Resources
Caribbean Water and Wastewater Association
2009 Conference
C f
and
d Exhibition
E hb
October 4-10, 2008
St. Thomas, USVI
18th Annual CWWA Conference and Exhibition
Reducing power consumption, conserving resources, and
reducing water price while upgrading and augmenting an existing
SWRO facility to meet increased water demand and plant
reliability in St. Maarten.
Shawn Meyer-Steele - William Sheehan
PROPRIETARY & CONFIDENTIAL
Introduction
-In 2007several factors were contributing to water shortages including
tourism and population growth as well as operational deficiencies at the
existing desalination plant.
-An immediate increase in supply was required in order to meet the
present demand and mitigate the potential for future shortages.
-The Cay Bay desalination plant was contracted to produce 13,500
M3/D but the outdated and inefficient plant was averaging 10,600 M3/D.
-The
Th power consumption
ti off the
th old
ld plant
l t was significantly
i ifi
tl hi
higher
h th
than
what is possible by state of the art plants, and was wasting precious
and expensive electricity.
-In
In the midst of this prolonged water shortage
shortage, Air
Air-Fin
Fin Holding St
St.
Maarten N.V. (AFH), (a wholly owned subsidiary of SSW) won a tender
to provide a new 3,000 M3/D potable water plant and take over
p
of the existing
g Cay
y Bay
y SWRO Plant for the St. Maarten
operation
Government.
PROPRIETARY & CONFIDENTIAL
2
Cay Bay Project Overview
• Under the Build Own, Operate and Transfer agreement signed
between the St. Maarten Government and Air Fin Holding St.
Maarten/Seven Seas Water Corporation, AFH/SSW would
upgrade, expand, maintain and operate the existing 3,600,000 US
gallons
ll
per d
day (USGPD) S
Seawater
t R
Reverse O
Osmosis
i (SWRO)
Plant at Cay Bay as well as design and build a new plant at
Cupecoy 1,000,000 USGPD SWRO Plant at Cupecoy.
• The water produced is supplied to the St. Maarten Power and
Water Authority GEBE, who distributes it to their residential and
commercial clients throughout
g
St. Maarten.
• This paper will address the practical and technical issues faced in
the design and operation of an outdated plant being redesigned
and
d upgraded
d d tto b
be as efficient
ffi i t as possible
ibl without
ith t interruption
i t
ti iin
the water supply.
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant History
• The Cay Bay Plant; St. Maarten has been in existence and
operating by numerous entities since 1986.
• The original (contract) was constructed and operated by Aqua
Design in 1986 under a ten (10) year BOOT agreement.
• In 1996 Enerserve N.V. (part of the Culligan group), was awarded
a sixty (120) month (BOOT) agreement from the St. Maarten
g
government
• At that time a new plant was built, (using some of the existing
infrastructure) with the production capacity increased to 2,150,000
US GPD (8,100
(8 100 M3/d) with
ith fifive (5) new SWRO ttrains
i and
d ttwo (2)
BWRO trains.
• In 1997 the BOOT agreement was expanded to include a sixth
(6th) SWRO train and a third (3rd) BWRO train for an increased
total production capacity of 2,587,000 USGPD (9,800 M3/D).
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant History
• In 1999 after US Filter purchased Enerserve/(Culligan), state of
the art technology at the time was implemented with the addition
of Dupont B10 permeators.
• In 2001 Enerserve/US Filter were one of the first to install ERI PX
ERD’s on a large scale plant at Cay Bay Plant in both a 2,520
M3/D and a 3,900 M3/D train, in cascade arrays.
• C
Cascade
d arrays are an iinexpensive
i d
design
i tto achieve
hi
more
potable water production from an existing plant but does not take
advantage of the full energy savings that could be gained by
utilizing isobaric energy recovery devices in a standard array
design.
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant History
• When AFH/SSW took over operation of the Plant in February
2008 it was in extremely poor shape, very unreliable, inefficient,
unsafe to operate and unable to supply contractual minimum /
island water demand.
• Seven Seas immediately started work on the planned upgrades
and improvements needed to ensure St. Maarten with a reliable
source of potable water with a greatly improved efficiency and
reliability.
PROPRIETARY & CONFIDENTIAL
Typical SWRO Plant
Chemical
Storage
Feedwater Supply
Pretreatment
Ultrafiltration
RO Building
(UF)
Concentrate Discharge
SRWO Unit
PROPRIETARY & CONFIDENTIAL
Product
Reservoir
SWRO Plant: Feed Water Supply
• Feed water is collected from a seawater intake or beach wells
• From the intake, a feed pump will convey feed water to the
pretreatment system
PROPRIETARY & CONFIDENTIAL
SWRO Plant: Pretreatment
• Multimedia filters, Bag Filters, etc
straining, interception
interception, impaction
impaction,
• 1st filtration step: straining
sedimentation, flocculation, and absorption
• (UF may be used in highly turbid waters as alternative to
filters to reduce lifecycle costs)
PROPRIETARY & CONFIDENTIAL
SWRO Plant: Sea Water Reverse Osmosis Unit
• Seawater Feed (wells or intake)
• Cartridge filtration
• Reverse osmosis (membranes, high pressure pump, piping)
• Energy recovery
• Concentrate Discharge
Clean-in-place
in place system
• Clean
PROPRIETARY & CONFIDENTIAL
SWRO Plant: Post Treatment
• Finish potable water
• pH
H balance,
b l
add
dd h
hardness
d
• Disinfection ((Chlorine,, UV,, Ozone))
• Chemical addition systems
PROPRIETARY & CONFIDENTIAL
Partial List of Upgrades Undertaken
• Among the long list of plant upgrades and system redesigns to
achieve the plant efficiency, dependability, reliability, safe
operation, and water demand that is the SSW hallmark are the
following:
• Intake/ Pretreatment / Post treatment
g
• SWRO Unit Redesigns
• BWRO, Partial 2nd Pass Units
• Safety / Electrical Upgrades
PROPRIETARY & CONFIDENTIAL
Partial List of Upgrades Undertaken
Intake/ Pretreatment / Post treatment
• M
Major
j portion
ti off intake
i t k and
d pretreatment
t t
t system
t
needed
d d to
t be
b re-designed
d i
d and
d
replaced.
• As the plant had over its long history been increased in increments there were
areas of hydraulic inefficiency where piping diameter had to be increased
increased,
bottlenecks eliminated and materials upgraded.
• There was a 38 PSI pressure drop across the pretreatment stages when
AFH/SSW took over the plant operation
operation.
• Additional media filters & cartridge filter needed to be added to ensure proper
design flows and proper velocities for adequate pretreatment, increased net
positive suction head ((NPSH),
p
) and g
greater flow.
• At one point in the system pretreatment there were two (2) 16” lines that fed to a
single 16” tee, which returned to dual 16” lines. This was redesigned to two (2)
separate 16” feeds.
• Four unused carbon post-treatment filters were converted to calcium carbonate
filters and put in service for improved product water quality.
PROPRIETARY & CONFIDENTIAL
Partial List of Upgrades Undertaken
RO Unit Redesigns
• A host of changes and improvements were implemented throughout the
Plant. The Plant can accommodate Seven SWRO units, of which Units
2,3,4,5, 6, and 7 were operating when AFH/SSW took possession of the
plant. The bay for unit number 1 was empty.
• A completely new Unit was designed and installed to replace SWRO
pg
with new controls and
Unit Six. Units Three and Seven were upgraded
more efficient energy recovery devices (ERI PX’s).
• SWRO Unit Five is scheduled for decommissioning after the redesigned
Unit Seven comes on line later this year after all redesign and upgrades
are complete.
• Two new, three-stage, high recovery (95%) second pass units were
installed to replace the older single stage (80%) recovery units
units.
PROPRIETARY & CONFIDENTIAL
Partial List of Upgrades Undertaken
SAFETY / ELECTRICAL UPGRADES
• Numerous safety enhancements ran the gamut from as simple as
improved grounding and lighting to more complicated projects
like the isolation of the electrical control system
system.
• SSW built 2 electrical rooms around main switch gear where
Motor Control Centers, control systems, and Variable Frequency
Drive motor controls were built to safeguard delicate electrical
equipment, prevent corrosion, improve efficiency through cooler
operating temperatures. There is also the added safety benefit of
a physical
h i l separation
ti b
between
t
th
the SWRO plant
l t ((with
ith pressurized
i d
seawater) and the electrical controls.
PROPRIETARY & CONFIDENTIAL
SWRO TRAIN DETAILS
Array
Membranes
Production
HP Pump
ERD
SWRO 1
Old*1
New*1
-
-
(M3/Day)
-
-
-
SWRO 2
Old
New
Old
3M/3M
3M/3M
Pelton/PX
Cascade
3M/3M
Toray-400
-
1,690
-
PD
PD
Centrifugal
Pelton
Pelton
Pelton/PX
New
Old
New
Old
3M/3M
3M/3M
3M/3M
Pelton/PX
Cascade
3M/3M
Toray-400
Toray-400
-
3,970
1,690
,
1,690
-
Centrifugal
P/D
P/D
P/D
PX
Pelton
Pelton
Pelton/PX
New*2
3M/3M
Toray-400
1,440
P/D
Pelton
Old
New
Old
New*3
3M/3M
6M
7M
7M
Dupont
Toray-400
Toray 400
Toray-400
3,970
3 970
3,970
PD
PD
Centrifugal
Centrifugal
Turbo
PX
Pelton
PX
SWRO 3
SWRO 4
SWRO 5
SWRO 6
SWRO 7
PROPRIETARY & CONFIDENTIAL
SWRO TRAIN DETAILS
*(1) SWRO Unit 1 was an empty bay on takeover, and plans are for it to remain so
into the foreseeable future
future.
*(2) SWRO Unit 5 will be decommissioned this year after the completion of
renovations for SWRO Unit 7.
(3) Later this year the SWRO Unit 7 retrofit will be complete
complete, including replacement
*(3)
of the High Pressure pump with smaller pump and ERI PX’s,
*(4) VFD motor control, new electrical gear, membranes, controls, and manifolds
provide a calculated reduction in the Unit # 7 electrical load from 850 to 400 Amps
* (5) All redesigned units with centrifugal high pressure pumps employ VFD control
and positive displacement pumps with soft starters.
PROPRIETARY & CONFIDENTIAL
BWRO TRAIN DETAILS
Array
Membranes
Production
Recovery
M3/Day
BWRO 3
BWRO 1
BWRO 2
BWRO 4
Old
1 Stage
Hollow fiber
-
80%
New*1
1 Stage
Hollow fiber
1,745
80%
Old
1 stage
Hollow Fiber
-
81%
New
3 stage
Spiral wound
2,100
95%
Old
1 Stage
Hollow Fiber
-
N/A
New
3 stage
Spiral wound
2,100
95%
Old
1 stage
Spiral wound
-
81
New*2
3stage
Spiral wound
1,963
95%
*1 - BWRO Three is an existing hollow fiber unit operating at 80% recovery in a single stage which will be
decommissioned for standby after completion of renovations.
2 – BWRO Four is a single stage spiral wound unit that will be converted to a three stage design with an
*2
increase in recovery from 81 to 90%.
PROPRIETARY & CONFIDENTIAL
Average Production and Energy
Consumption at Cay Bay
LEGEND
------ Daily production m3/day
----- Electrical consumption kWh/Day
PROPRIETARY & CONFIDENTIAL
CAY BAY PLANT DETAILS
Cay Bay Plant Capacity:
•Contractual: 3,564,000 US Gallons per Day (13,500 M3/D) in Six Units
•Partial second pass in 4 units.
y
Product Quality:
•Actual: <280 uS/cm
•Contract: <300 uS/cm
Power Consumption:
•On takeover: ~22 kWh / KIG (18.2 kWh/KUSG)
•Actual at Present: ~16 kWh / KIG (13.3 kWh/KUSG)
Act al at Present ~16 kWh / KIG (13 3 kWh/KUSG)
•Completion of upgrades: Estimated ~14.0 kWh / KIG (11.7 kWh/KUSG)
PROPRIETARY & CONFIDENTIAL
CAY BAY ENERGY IMPROVEMENT
- Seven Seas Water is presently 80% complete with a multi-million dollar upgrade and efficiency improvement project.
-Specific energy consumption has been reduced from over 18.3 kWh/KUSGal to an average 13.3 kWh/KUSGal at
present.
p
-When all upgrades are have been completed, final electricity consumption is expected to be 11.7 kWh/KUSGal,
approaching the energy consumption of the newly constructed Seven Seas Cupecoy Plant.
PROPRIETARY & CONFIDENTIAL
Table
bl One: Cay Bay Plant
l
monthly
hl electrical
l
i l consumption
i
2009 Cay
y Bay
y Monthly
y Electrical Consumption
p
- kWh / KIG
t)
O
ct
(
es
t.)
(e
s
Se
p
ctu
(A
n
ay
M
Ju
(A
ctu
ua
ct
(A
Ap
r
al)
al)
l)
l)
ua
ct
M
ar
(A
Fe
b
(A
n
Ja
(A
ct
ctu
ua
al)
l)
22
21
20
19
18
17
16
15
14
13
12
The savings are calculated to be over 29,700 kWhr per day (or USD $1,300,000 per year in electricity costs
assuming electrical costs of US$0.13/kWhr).
This is a reduction of over 120,000 tons of CO2 emissions per year (based on 2 pounds of carbon emissions per
kilowatt hour generated by a average commercial diesel generator).
The reduced power consumption frees up previously dedicated energy generating equipment for other needed
projects without requiring new installed capacity, and significantly reduces the carbon footprint of St. Maarten.
PROPRIETARY & CONFIDENTIAL
Table
bl Two: Cupecoy Plant
l
monthly
hl electrical
l
i l consumption
i
2009 Cupecoy Monthly Electrical Consumption - kWh / KIG
al)
al)
(A
n
Ju
(A
ay
M
ctu
ctu
al)
r(
Ap
ar
M
Ac
ct
(A
ct
(A
b
Fe
tu
ua
l)
ua
al)
ctu
(A
n
Ja
l)
22
21
20
19
18
17
16
15
14
13
12
The recently commissioned Seven Seas Water SWRO Plant located at Cupecoy Yacht Club, Sint Maarten.
Present electricity consumption is less than 14 kWh per 1000 imperial gallons produced = 11.7 kWh per 1000 US
gallons.
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant: The Old and the New HP Manifold
OLD High Pressure Manifold Design NEW High Pressure Manifold Design
Seven Seas completed numerous improved manifold designs with lower pressure drops, improved performance and
utilization
tili ti off materials
t i l meantt tto llastt 20 years.
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant: HDPE Installation #1
This first set of piping redesign resulted in decrease in the pressure prop across the system and an increase in the
feed pressure to the feed pumps of 5-7
5 7 psi
psi.
This resulted in an increase in the existing plant production capacity by ~800-1000 m3/day
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant: HDPE Installation #2
The Second HDPE re
re-design
design increased the feed pressure to SWRO units by another 2 psi
psi.
PROPRIETARY & CONFIDENTIAL
Cay Bay Plant: New Cartridge Filters
Two new cartridge filters housings helped reduce the pressure drop across the Cartridge filter area.
The changes reduce the pressure drop by ~ 10 psi through the pretreatment and assists in achieving the design
capacity of 13,500 m3/day.
It also assists with the high pressure pump performance by providing additional net positive suction head (NPSH)
(NPSH).
Additional changes to the outlet (converting from 14’ to 16”) piping also resulted substantial reductions in pressure
drop.
PROPRIETARY & CONFIDENTIAL
SWRO Train Number Three Redesign
SWRO Train #3 was completely redesigned, eliminating the less efficient hybrid Calder Pelton Wheel/ ERI PX
Cascade Design for a 100% isobaric ERD design with improved manifolds, and low pressure membranes.
PROPRIETARY & CONFIDENTIAL
SWRO Train Number Three Redesign
E
F
Membranes
C
ERT
HP Feed D
Pump
B
PX
PE
G
H
M b
Membranes
J
A
K
Previous Design
g with ERI PX Cascade Design
g Utilizing
g Pelton Wheel
PROPRIETARY & CONFIDENTIAL
SWRO Train Number Three Redesign
E
F
MEMBRANES
D
C
Feed
Pump
Booster
Pump
G
PX
A
B
Re-Design
g with ERI PX Cascade
PROPRIETARY & CONFIDENTIAL
H
SWRO Train Number Six Replacement
When Seven Seas took over the plant, Unit Number Six was still operating with the discontinued Dupont B10
permeators which deliver exceptional permeate quality but at very high feed pressures (1000 PSI +) with very high
energy consumption. .
PROPRIETARY & CONFIDENTIAL
SWRO Train Number Six Replacement
New SWRO Train Six operating.
This unit was replaced with a 100% isobaric ERD design with improved manifolds, and low pressure membranes
PROPRIETARY & CONFIDENTIAL
Cay Bay: New 2nd Pass BWRO Units
The two existing
g second p
pass brackish water reverse osmosis ((BWRO)) units ((hollow fiber)) have been replaced
p
with
new high recovery units.
Old BWRO units operated at 81% recovery and the new units operate at 95% recovery.
PROPRIETARY & CONFIDENTIAL
CUPECOY PLANT DETAILS
Cupecoy Plant Capacity:
•Actual: 1,003,200 US Gallons per Day (3,800 M3/D)
•Contract: 792,000 US Gallons per Day (3,000 M3/D)
•Partial second pass.
Product Quality:
•Actual: <280 uS/cm
•Contract: <300 uS/cm
Power Consumption:
•Actual: ~11 kWh / KIG
Design: ~11
11 kWh / KIG
kWh / KIG
•Design:
Schedule
•Contract Award 7/30/07.
•Plant Operational 1/8/08.
•Less than five (5) Months to Complete from contract award to water production
PROPRIETARY & CONFIDENTIAL
1 MGD SWRO Cupecoy Plant
PROPRIETARY & CONFIDENTIAL
Public / Private Partnership
The Cay Bay and Cupecoy Plants provides a total of 17,300 M3/D
((4,567,300 US Gallons per
p Day)
y) of desalted, p
potable water in a Public /
Private Partnership.
The PPP utilizes the best of both the St. Maarten Power & Water
Authority (GEBE) and AFH/SSW to provide the lowest cost water
solution with the highest possible reliability to St. Maarten.
AFH/SSW guarantees quality and quantity of potable water production
as well as responsibility for all costs to maintain the plant.
GEBE and AFH/SSW share operation, engineering, mechanical and
technician responsibilities with almost all staffing of the plants by GEBE
personnel.
The net result of the various improvements made to the plant under the
BOOT demonstrate that a real public/private partnership between a
municipal entity and an experienced, financially solid service provider
can yield
i ld exceptional
ti
l results
lt achieving
hi i allll th
the stated
t t d goals.
l
PROPRIETARY & CONFIDENTIAL
36
Conclusions and Results
In less than 5 months from the time the water contract was
signed a state-of-the-art
signed,
state of the art 3
3,800
800 M3 /D SWRO desalination
system was constructed at Cupecoy under a BOOT
arrangement.
SSW restored
t d the
th existing
i ti plant
l t att C
Cay B
Bay tto itits 13
13,500
500 M3 /D
capacity and greatly improving the efficiency with a system
redesign.
With the reduced power consumption, the price of water to the
St. Maarten government was able to be reduced.
The new Cupecoy plant and a significantly improved Cay Bay
plant ensure the long-term water needs of St. Maarten.
Additionally, the power demand of the Cay Bay Plant has been
significantl red
significantly
reduced,
ced ccutting
tting carbon and other emissions and
freeing up valuable resources in the process.
PROPRIETARY & CONFIDENTIAL
37
CONCLUSIONS and RESULTS
- In examining the overall lifecycle costs of upgrading and expanding the
capacity of an older SWRO plant, taking into account energy consumption,
operating costs, equipment replacement and reliability the best re-design
may not be inherently apparent.
-After factoring in dependability of design, various savings through efficiency
improvement, environmental concerns, and sticking within very strict
workplace safety guidelines AFH /SSW decided upon a number of different
approaches for the six (6) operational SWRO and two (2) BWRO trains
depending on their condition and other factors.
-Two seawater RO and two brackish water RO units were completely
replaced while others had varying degrees of redesign and rehabilitation.
-Combined with improvements in pretreat, posttreat, the combination of
upgrades helped AFH/SSW more than meet their electrical consumption
g ,p
production capacity,
p
y, and on-line time.
targets,
PROPRIETARY & CONFIDENTIAL
PLANT CONCLUSIONS and RESULTS
-The consumption of electricity at Cay Bay from approx 28,470 mWh per
year down to 19,162 mWh per year for a net reduction of 9,308 mWh per
year or approx 9,300 metric tons of carbon per annum going forward.
- The people of St. Maarten now have a guaranteed supply of water that is
produced with reduced energy consumption, greater reliability, a lower cost
supply of potable water, and a sufficient quality to meet the needs of the
people off St.
S Maarten now and well into the future.
f
PROPRIETARY & CONFIDENTIAL
Questions?
.
PROPRIETARY & CONFIDENTIAL