Hatfield Marine Science Center
Seawater System Recommendations Report
David Applegate, OSU ESE
September 2013
Introduction
The following includes brief overview of the Hatfield Marine Science Center’s
development and use of seawater. The users and their requirements are described, as well
as a walk-through of the operations of the system that delivers the seawater. There are
numerous recommendations for taking advantage of energy and/or cost saving
opportunities, most can be done independently at any time.
History –
The Hatfield Marine Science Center was opened in 1965. The facilities have
grown over the past 47 years to accommodate six different organizations and all their
research and administrative needs. OSU, NOAA, EPA, ODFW, USGS and USFW, share
the campus and work together to fund the continuing development of the site. While the
original seawater system consisted of two intake pumps and lines, which fed storage
systems that evolved from smaller tanks to open ponds, the existing system uses an
additional two pumps and lines to feed an 800,000 gal reservoir. This upgrade was made
in 1992 in order to increase maximum flow capacity, while solving multiple bio-fouling
issues. In 1997 the visitor’s center was remodeled and their seawater infrastructure and
demand increased considerably. 2005 brought new environmental regulations that lead to
the implementation of a settling pond to minimize organic debris discharging to the bay.
Sand filters were installed in 2006 that provide seawater filtered to 50 microns to the
majority of the users, with EPA being the only raw water user.
Users –
Currently the system supplies a total of approximately 500 gpm on average to
researchers, educators, and public access displays. The visitor’s center is comprised of
local and exotic spices of aquatic life, including a life octopus, and an open live touch
take modeling a tidal pool. There are also numerous interactive tsunami exhibits. All
together this consumes a fairly consistent 120 gpm. The Educational Wing is home to
four classroom laboratories used for both college level courses and youth programs. The
flow rates are more seasonal but currently average about 10% of the total demand.
Research is the main focus at HMSC and seawater is the lifeblood of their
operations. Current research projects include an ocean acidification study through
Alaskan Fisheries/NOAA housed in the Research Support Facilities building. Their
consumption is relatively low right now at about 120 gpm, but during a ramped up phase
in the spring, they are generally closer to 350 gpm. The water used in these studies must
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replicate the natural habitat of the Alaskan seas, therefore, a glycol cooling system with
15 heat exchangers is used to chill the water to anywhere from -1 to 10 degrees C.
Another extensive study being conducted right now is targeted at researching
mollusks. The local oyster industry is a staple of the Oregon coast and the knowledge
gained at HMSC proves to be invaluable. The 70 gpm consumed for this study is more
or less unchanged once it passes through the overall filtration system. The Fish Disease
Laboratory is another major long-term user, and with a revolving door of smaller, short
term studies, along with the permanent fish clinic, the seawater demand fluctuates usually
between 300 to 800 gpm.
System Overview –
In order to facilitate all of these projects and the sea life that accompanies them,
HMSC has an elaborate system of intake pumps and lines, stored reserves, filters, and a
distribution network weaving through the 49-acre campus. The trip for the seawater from
the bay to the take begins exactly an hour and a half before each high tide. At that time, a
vacuum priming system pump is set to start. The priming pump sucks seawater up about
15 feet to fill the intake pump impeller housing and prevent cavitations. Once the levels
are high enough to flip the float switch, one of the four main pump is activated and
begins pumping seawater to the reservoir. Five minutes later the same series of events
happens for a second intake pump. Only two of the four intake lines (Red, Green, Blue,
Yellow) are in service at any given time, and the two are switched every six weeks to
minimize marine growth and clogging.
The two 50 horsepower pumps run for a set 3 hour pumping cycle through two
ten inch lines. This allows more than enough time to fill the reservoir about 600 feet
away. This also insures the highest quality of seawater possible as the pumping cycle
surrounds the high tide apex where the bay is mostly ocean water. Depending on the rate
of use, the reservoir tanks generally do not get much below half full, but the extra
capacity is necessary should the demand increase, or if there are any issues with the
intake system that may prevent filling of the reservoir.
The reservoir is composed of four conjoined tanks plumbed together by an intake
manifold on the rear exterior wall designed with full redundancy to allow any of the four
lines to fill any tank or combination of tanks. The interior wall also has a manifold
connecting the four tank outlets, with an additional upper manifold for redundancy. The
main manifold leads directly to the main distribution pumps for the Red and Blue lines,
along with pumps for the EPA’s supply. There is also a reservoir bypass line coming
form the rear manifold that allows seawater to be pumped from the intake pumps to the
distribution network without entering the reservoir.
The distribution line is pumped first into one of four separate sand filters to
remove the majority of biological and foreign mater while still preserving the authenticity
of the seawater. After the filters remove anything over 50 microns, the seawater travels
down a series of lines ranging from eight inch down to two inch which sprawl out to feed
39 different supply valves. After the seawater has fulfilled its purpose for whatever user
it serves, it is passed to a drainage canal in what is known as a flow through system,
meaning the water is used and returned to the bay as opposed to cycled through filters or
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other users. Some of the spent water is left unprocessed and channeled right back to the
bay, depending on what it was exposed to. However, if the seawater was used in a way
that may have introduced anything that was not already present, it is sent to the chlorine
treatment system before returning to the bay.
To treat the seawater to an expectable standard that is actually cleaner than it was
when it came out of the bay, the seawater is mixed with chlorine to a concentration
capable of killing off anything in the seawater. Flow monitors track the volume of water
entering the treatment pond and a control system adjusts the chlorine introduction drip to
ensure an adequate solution of .01%. There are two separate chlorine treatment systems,
each treating about 140 gpm.
The Red and Blue distribution lines are alternated into and out of service just as
the intake lines. Over a six-week period the seawater in the unused line is kept stagnant
and allowed to go anaerobic, meaning all of the oxygen in the water is depleted and any
marine growth is neutralized. The line change is a process creating loops in the
distribution network to force the fouled water back through the system and into the
settling pond. This allows organic debris to settle out before the water returns to the bay,
while protecting the seawater users from contamination.
Pros/Cons –
Analysis of the seawater system has revealed great potential for minimizing
energy use and maximizing overall efficiency by simply replacing outdated and/or
pieced-together equipment with what is the current industry standard. While the facilities
were appropriately designed at the time of their development, there have been many
technological advances in pumping systems. Additionally, the talents of the facilities
staff have allowed them to successfully make do with the resources available to keep the
system operational with no major interruptions in service. However, this has led to a few
weak links that undermine the reliability of the entire system while inhibiting optimal
operation. Some equipment has reached the end of its designed service time and will
unavoidably need to be replaced, whether scheduled or unexpected, regardless of the fact
that they have become wastefully inefficient.
As undesirable as that sounds, this actually puts us in an advantageous position.
Making relatively simple and already necessary upgrades to revamp the antiquated and
expired seawater system will bring multifaceted benefits. As OSU is renowned as energy
intelligent, “green”, doing a system upgrade with energy efficiency as the paramount
driver will help to prove our commitment to being an environmentally and energy
conscious organization. By not only reducing what we use, but also optimizing what is
used to accomplish more, we can showcase our capabilities to work toward building a
sustainable future and being part of the solution. In addition to positive public relations,
a system overhaul will also leave us with a more dependable, and predictable delivery
system. The upgrades simplify the system and leave it with less to go wrong while
providing more information about the seawater and it’s use. Finally, the cost savings are
an undeniable factor that, even with out the other benefits, warrant the proposed
recommendations be pursued.
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Recommendations –
These recommendations are made with the intent to increase the overall efficiency
of the seawater system. Electrical power, man power, financial resources, and down time
are all minimized to create a system with optimal output versus cost without sacrificing
reliability or quality. Some suggestions require only changes in operating procedures;
others are physical changes to the system itself.
Install a Variable Frequency Drive on the intake and distribution pump systems
As shown in appendix H, there are various options available to increase the
efficiency of the intake system. By installing a VFD (variable frequency drive) we gain
much more control of the pumping system, including the ability to change the speed of
the pump motor to a rate that will fill the reservoir exactly to the rim over the same threehour cycle, without wasting any energy by overflowing the tanks and without altering the
quality of the seawater. Since the relationship between pump speed and power required
is not linear, but actually cubic, any reduction in speed translates to eight fold reduction
in power use. When pumping time remains constant, reducing the volume pumped to
60% drops the power demand to 22%. Therefore, maintaining the duration of pumping
cycle at three hours, which would normally pump over 527,000 gallons, but slowing the
pumps to move only the needed volume of about 309,000 gallons of seawater to refill the
tanks can potentially save upwards of $8,200 a year, with a return on investment of about
seven months.
This also greatly increases the reliability of the control system. The current brain
for the pumps is a series of relays and timers, that has served its purpose well, but is an
Achilles’ heel that is not user friendly, nor familiar for anyone who may be servicing it.
The power demand required to run the pumps is also greatly reduced which contributes to
the total savings. Reducing the power demand from 73.5 kw down to 14 kw accounts for
about $4,800 of the savings.
This is not the fist time a VFD has been recommended. The march 16, 2009
“Save Energy Now Assessment Report”, number 2002 sponsored by Bonneville Power
Administration for HMSC (link provided in references) included five suggestions for
energy savings that, if implemented, would have saved $113,500 by now. This analysis
also reported a possible 84% reduction in pump operating costs.
Similarly, appendix I shows the potential savings for a distribution pump outfitted
with a VFD. Because the pump is ran at full power and rated to deliver twice the average
demand, over three times the energy is used than needed. By slowing the pump to a point
that matches demand we can save $7,200 a year. To illustrate this better, picture yourself
driving a car with your gas peddle floored, and you only use the breaks to slow the car
down. Your fuel efficiency would be horrible and it would make no sense to drive like
that. Yet, this is how the distribution pumps are set up right now.
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Run additional pumps in parallel
By running three of the four intake pumps can drop the speed of the pumps again
and exploit the power savings even further. Also, splitting the flow between three
pipelines reduces the velocity of the fluid flow inside the pipes, which results in less
friction losses. Reduced friction lowers pump power needed and also lowers the increase
in temperature of the seawater. This would require more line changes and cycling each
line through a dead phase every fourth time in order to keep the pipes free from bio
fouling. Adding the third line with the VFD control would bring the total savings for the
intake system up to $8,900 a year, however the savings will be reduced by labor costs for
the additional line changes. Fitting the valves with automated electronic actuators would
ease the process.
Automate all line changes with electronic valve actuators
In conjunction with a VFD, automated valves are able to monitor the friction
losses caused by growth in the lines and based on adjustable parameters the system can
automatically backwash the fouled seawater at the optimal time, bring the pipe back
online and seal off the next pipe to go anaerobic. Having computerized controls for these
sequences will insure consistent valve manipulations and prevent cross-contamination.
Manpower required for line changes will be nearly eliminated and the system can be
monitored or changed from an office or remote device. Unfortunately, with a sizable
initial investment, the payback period is close to 25 years, therefore the real value in this
upgrade is in reliability and functionality.
Upgrade existing intake pumps with high efficiency submersible pumps
The pumps used today are well past their life expectancy and have deteriorated to
60% efficiency. They require two separate cumbersome vacuum priming systems with a
complicated series of events that must take place before any seawater can reach the
reservoir. Also, they are not designed to be seawater pumps, which has led to their
internal parts being eaten down to a point that drops the initial maximum flow capacity of
720,000 gallons per pumping cycle down to only 527,000 gallons. This puts the designed
delivery of 1000 gpm from the reservoir out of reach.
By replacing the outdated pumps with high efficiency submersible pumps we no
longer have to maintain a vacuum priming system, we improve our maximum flow
capacity, and we bump our efficiency back up to 90%. The system is simplified and
renewed to a much more dependable state. Despite an investment of $22,000 per pump,
the higher efficiency combined with a VFD allows a payback period of just over eight
years. When the lifespan of the pumps are considered, the total savings is still at least
5,000 dollars a year. Another benefit of submersible pumps is they don’t need a pump
house building. If need be, the controls can be moved to the auxiliary generator building
and the twenty thousand dollars needed to replace the pump house can be put toward the
pumps themselves.
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Upgrade the distribution pumps to high efficiency pumps
The distribution pumps are also deteriorated and at the end of life. The annual
savings even after paying for the pumps is still about $9,000 if installed with a VFD.
Reconfigure EPA pumps
The pumps used to supply water to the EPA building are vastly oversized at the
moment. Right now there is a pump designed to move almost 1500 gallons per minute
pushing seawater to a valve two fee away that restricts the flow down to about 10 gpm.
This is a gross waste of energy. Granted, the EPA’s demand is subject to change, but the
average seawater delivered over the last year compared to the power used to supply it has
incurred about $4,400 more than it should. Appendix J has many options to correct this,
but the easiest and most economical would be to divert water form the main line to
supply the EPA. At 10 to 20 gpm, the EPA would not have much of an effect on the
main line flow, and if the demand ever increases too much, the original EPA pump can be
re-introduced to supplement the demand.
Install overflow ports between the smaller and larger reservoir tanks
A valve to restrict the flow throttles down the intake pipes for the 100,000 gallon
tanks on the exterior of the reservoir. This allows the smaller tanks to fill at closer to the
same rate as the larger 300,000 gallon tanks. Limiting the flow with a half open valve
causes added head loss and increases the pump power required. By opening a passage
between the tanks that would allow the overflow from the smaller tank to help fill the
larger thank, and changing all valves to full open, the reduction in power needed would
save nearly $400 a year.
Re-automate sand filter backwash and bring fourth filter back online
The sand filters are already set up with automatic backwash controls which sense
the difference in pressure form the intake and the outlet to determine when the sand is
dirty enough to need cleaning. Usually a couple of times a day the flow is reversed
through each of the filters and the debris is channeled to the settling pond. Currently the
system is not operational and manpower is used to manipulate the valves. There are
savings in reduced labor costs and also in lower pump power required since the
automated system will perform the backwash as needed where as right now it is done
when there is time, and the more debris the flow must pass through, to more power is
required to push it.
There are four sand filters installed, however only three of them are in service.
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Bringing the fourth back online would reduce the rate at which the filters need to be
backwashed, and also allows for less restricted flow. Presently, the overall maximum
flow capacity bottlenecks at the filters, and having only 75% of the flow available
severely hinders the system.
Reconfigure lines to eliminate backtracking and document any changes
The distribution lines are often changed to accommodate research projects and
alterations to the facilities. Up until now there has been no documentation or reference
for the lines, so the system became somewhat unrecognizable. Some lines were no
longer in service, while others had no clear destination. A few lines make unnecessary
backtracks that add friction losses and clutter to the layout. A more streamlined pipe is
always more efficient, and it also reduces guesswork for the facilities staff. The lines
supplying the touch tank and octopus tank in the visitor’s center can be reconfigured to
avoid about 150 feet of loops, bends and a run under a building. Connecting them near
the #1 valves would give them a straight shot into the visitor’s center.
A full one-line drawing of the current system has been produced as a visual tool
to track every line and valve in the system. Any future changes should be reflected in
this drawing to keep it up to date and useful.
Install a monitoring system
The flow of seawater through pipes at various velocities affects it’s temperature.
As the velocity of the fluid increases, the temperature will follow due to the friction of
the fluid against the pipe wall creating heat. Additionally, the time spent between when
the seawater is pulled form the bay to when it reaches the lab allows it to approach
ambient temperature. The labs further away from the reservoir will experience different
temperature fluctuations than those that are closer.
Since the seawater is used for research and/or replicating the natural environment
for the marine life, it is important to find the balance between heating the water by
moving it through the pipes too fast and letting it naturally warm up by taking too long
for delivery in order to keep the seawater as close to the original temperature as possible.
Also, for the labs that chill their seawater, the more heat that is add upon delivery, the
more energy it will take to chill it back down.
A complete monitoring system is essential to monitor the flow, temperature,
salinity and quality of the seawater as it is supplied. This will provide important data for
considerations in appropriate research placement, for determining the appropriate flow
rates, for providing historical data of the system performance, and for researchers to
reference, as research conditions are highly delicate and unknowns are unacceptable in
determining reliable results.
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Introduce a utility model and adhere to a replacement schedule
Having access to flow demand also allows for instituting a utility model that will
allow for a charge per use of seawater. This income will serve to supply the energy for
seawater pumping, along with covering the labor and materials costs associated with
providing seawater to the labs. The facilities costs in appendix A are broken down to
show what should be spent every year to insure the system stays up to date. On average,
nearly seventy thousand dollars worth of equipment expires annually, yet it is still in
service. Currently there is no funding to support the cost of replacements, but the rate
structure shown in appendix D could be used to charge users based on their demand, and
with that income, cover operations costs and re-invest in upgraded replacements as the
equipment reaches its end of life. Making users aware of their seawater usage will also
help to minimize wasteful practices in their research. The use of seawater is expected to
become exceedingly efficient when the users are more conscious of their consumption,
and that is has a monetary rate attached.
Use flow calculation tool
A dynamic electronic version spreadsheet in appendix K has been provided to
help optimize research project placement based on flow availability and demand
requirements. These flow calculators can be referenced to determine the best
configuration for wet lab space devoted to given research. By matching individual
research projects to wet labs based on the optimum flow available and minimum flow
needed, the entire system can be optimized.
Implement a salt chlorine generator
The seawater treatment system presently demands over $60,000 a year of very
hazardous chemicals to be transported and stored on site. The exposed chlorine is
dripped into the water by an elaborate system of sensors and pumps. The highly
corrosive and dangerous chemicals require constant observation and handling by
personnel.
A salt chlorine generator uses the natural salt in the seawater to produce the
treatment chemicals by electrolysis. A portion of the seawater flow is diverted into the
self-contained equipment, where in it passes through two electrically charged surfaces
and the sodium is temporarily broken down into hypochlorous acid and sodium
hypochlorite. These sanitizing agents propagate through the seawater to kill any foreign
organisms, and eventually the chemicals naturally reconstitute to become the same
original salt in the seawater.
This is a simpler, user friendly, safer, and much cheaper process that doesn’t put anything
in, or take anything out of the water. The initial investment for the equipment is between
$20,000 and $30,000, with annual expenses for cleaning components routine
maintenance. However, the salt is already present and the overall savings would be 80%
of the current costs. If a complete system replacement is not approved, at the very least, a
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salt chlorine generator could be used as a supplemental system to minimize the cost of
chlorine purchased.
Conclusion
There is a plethora of opportunities for energy optimization and cost savings that
will begin to pay for themselves immediately, and go on to save huge sums of money for
the lifetime of the facility. With the system already in serious need of replacement
equipment, now it the most opportune time to take advantage of the technology available
to increase efficiency, reliability, and environmental responsibility.
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References
Adjustable Speed Drives As Applied To Centrifugal Pumps.
March 2000. Reliance Electric
http://www.reliance.com/prodserv/standriv/appnotes/d7737.pdf
Save Energy Now Assessment Report, number 2002. March 16, 2009
Bonneville Power Administration.
http://ir.library.oregonstate.edu/xmlui/handle/1957/39689
Affinity Laws. Fluide Design
http://www.pumpfundamentals.com/yahoo/affinity_laws.pdf
Pump System Curves. Engineering ToolBox.
http://www.engineeringtoolbox.com/pump-system-curves-d_635.html
Electric Service Rate Schedules. Central Lincoln PUD.
http://www.clpud.org/pdf/CLPUD_rate_schedule.pdf
Onsite Hypochlorite Generation from Seawater. Seaclor/Sanilec.
http://www.vicel.com.br/sites/default/files/files/STDN_seaclor_sanilec_onsite.pdf
How To Size A Pump. November 11, 2009. Blackmonk Engineering
http://blackmonk.co.uk/2009/11/11/how-to-size-a-pump/
Brochure B-1275. 2003. Peerless Pump Company
http://peerlessxnet.com/Documents/B-1275.pdf
Life Cycle Costs: A Guide To LCC Analysis For Pumping Systems. January 2001
https://www1.eere.energy.gov/manufacturing/tech_assistance/pdfs/pumplcc_1001.pdf
Fluid Mechanics Sith Edition. Frank M. White
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