Air Handaling UnitsRecently the old chillers in the Edwin L. Jones building were replaced with new more energy efficient chillers. Along with this energy savings, the MS IC shop was looking for other ways to save energy and money. The idea to reclaim the Jones building's five air handling units cooling coil condensate water became a Technical Systems Division goal. This water normally just goes down the drain. The cooling towers need the water because they loose a certain amount of water to evaporation, especially during the summer months, to evaporation. The water is currently being replaced with city water at Duke's expense. Also, when the water leaves the chillers, it's about 90 degrees. Fans are used to cool the water. The reclaimed water is about 50 degrees so it takes less energy to cool.
The Technical Systems division designed a condenser water reclaim system to recycle this water to the cooling towers. The system works by using small condensate pumps that are installed at each air-handling unit. The pumps were interlocked with the chiller condenser pumps, so if either chiller condenser pump is running, power would be sent to the small condensate reclaim pumps. The condensate water is pumped from each air handling unit to a holding tank. As the holding tank fills with condensate water a series of float switches control the holding tanks and injection pump which pumps the water to the cooling tower. There are two points that are monitored by the BAS room. One is a tank overflow alarm and the other counts and totals the gallons per minute reclaimed.
The system started August 9, 2000 and as of November 1 we have reclaimed 471,533 gallons of condensate water. The estimated savings is $2,030.70 for three months. Over the course of a year, 2 million gallons of reclaim water savings are estimated to achieve a one and one half year payback on the reclaim systems installation costs.
The Technical Systems division was not in this project alone. WMS helped install the system.
Hats off to the MS 1 C shop, Technical Division, WMS shops, and all who helped make this money saving idea a great success! 2 of a Manager and Supervisor in the Traffic and Parking Division.
J. William (Bill) Baker will assume responsibilities as Manager, Transportation, Parking and Facilities effective January 1, 2001. Bill has been the Parking Superintendent for the City of Columbia in Columbia, South Carolina since May, 1997. Prior to that he was the Director of Parking Operations at the University, of South Carolina for 12 years. Bill brings to us a successful background in business management with an emphasis on customer service. We look forward to his arrival in January.
Also recently announced was the appointment of Bruce Temple as Supervisor for 2nd shift. Bruce has been an employee of Traffic and Parking since August, 1999 and at Duke since April, 1997. He has previous supervisory experience and over 23 years of experience in law enforcement. He assumed the supervisory duties effective December 18, 2000.
Ultrasonics Find Steam Loss At Duke Medical Center
by Jeff Shambley
In May of 1998 Duke University Medical Center (DUMC) Technical System’s Manager, Mike Herran and I initiated a steam trap survey program using state-of-the-art ultrasonics technology.
In the first year alone we saved DUMC almost $400,000 in steam cost and more than 62 million pounds of steam compared to the year before without the program.
Duke University Medical Center (a separate entity from Duke University) is one of the largest medical centers in the world. It covers nearly 5 million sq. ft. and is in a constant state of growth. The Research facilities account for 2.3 million square ft; Duke Hospital covers nearly 1.3 million sq. ft. and Duke Clinic, the original 70-year-old outpatient facility formerly called Duke South is over 1.3 million sq. ft.
In 1998 Mike Herran contacted the North Carolina Department of Energy (NCDE)about utilizing a rebate program for steam trap testing. This program is designed for privately held companies and non-profit organizations. The funds for this program are a result of federal government fines’ against Exxon due to shipp9ng lane violations. NCDE has supported develop8ing program’s that save energy by subsidizing steam survey cost. Thanks to Rita Joyner this program has worked well for us.
DUMC’s Engineering & Operations (E&O) selected Bruce Gorelick from Enercheck System’s as a consultant to visit DUMC and to conduct a steam trap survey. Using the Ultraprobe 2000 (manufactured by U.E. System’s Inc. Elmsford, NY) we surveyed our facility for faulty steam traps. I watched, listened and learned so I could continue with the preventive maintenance program on my own.
How Steam Leaks and Ultrasonics work.
Steam leaks are everywhere. Steam can escape through external or internal leaks in fittings, valves, traps or particular control devices. The trap leaks may be due to over sizing, some may be blowing. Some are leaking through the disc and seat but not at it’s full potential. Some traps are plugged with dirt causing to fail in a closed position. Steam BTU’s can also be lost through un-insulated PRV’s, valves and piping etc. We try to pay close attention to this aspect of steam loss as well. Blowing or leaking traps may also cause a high backpressure in the condensate piping. The backpressure may be even greater when condensate piping is undersized which leaves no provisions for flash steam. Excessive condensate load may be caused by failed control valve’s too. When control valve’s are grossly oversized, they are forced to work in close tolerance to the disc and seat.
High Velocity steam acts almost like sandpaper cutting the disc or seat as the steam is forced through the tiny crevice. This results in premature wear called wire draw..
Fluids moving from the high-pressure side of a valve through the seat to the lower pressure side produce turbulence. This generates ultrasound, which an ultrasonic detector translates via a process called heterodyning into the audible range of human hearing. The ultrasounds are heard through headphones and viewed as intensity increments on the handheld instrument’s meter. High frequency tuning allows the user to adjust for differences in fluid viscosity. E.g. water vs. steam, and reduces any interference from stray pipe noises.
Longer wavelengths of low-pitched frequency sounds easily penetrate solid materials making them difficult to localize and can be heard without special equipment. But higher-frequency sounds that do not penetrate most solids will slip through the tiniest of openings. As a result, ultrasonic detectors are ideal for isolation sound sources such leaks.
We began our survey with a comprehensive inspection of every aspect of the steam system throughout our Research facility, building by building. At each site, we located where the steam line entered the building and then traced every inch of the system, including control valves, electric solenoids and steam traps. We checked to see if pressure was controlled correctly and whether or not relief valves were blowing steam through the roof. The length of time spent on these exploratory jobs varied based on the size of the building. The smaller ones could be completed in a day. We managed to locate 2,100 steam traps in the facility.
We have basically four styles of traps at DUMC. Thermodynamic traps are by far the easiest trap to test. Float and thermostatic traps’ (F&T) take more time to listen for the particular operation of each trap, i.e. when the ball is seating off causing a tapping sound. The thermostatic trap which is usually turned up to full load for better and more understandable listening and last the bucket trap while being the most durable, generally I found it to have the highest failure rate here at Duke.
Over time, we have decided to replace all bucket traps. If they are into the main “drip-legs” where we have constant pressure, we replace them with thermodynamic traps. Where there is a modulating control valve on a coil or heating ramp that has variable demands, we replace it with an F&T trap.
Steam trap survey ultrasonic techniques.
It is important to study the different function of different types of traps. Basically I touch the ultrasonic instruments contact probe to the trap and listen for tell tale signs of proper operation through the headphones. Frequency adjustments may need to be made especially when there is a lot of piping noise due to high velocity through PRV’s and valves.
When we began replacing steam traps, which we call the “end-of-the-mains” or “drip-leg” traps, we installed a test T (?) so we could observe how a trap operates as we were listening to it. This made it easy to learn what a correctly operating trap sounds like. Quite simply a good trap is fairly quiet until just before it is about to discharge. We then started to hear it nudging off the seat a bit against the inside, and suddenly we heard a full blow that stops almost immediately.
When we test for a failure condition in thermodynamic trap, we listen for there different things: silence signifies a flat-out failed closed trap; a soft, even high-pitched rushing sound signifies a wide open blow through so we can tell there is nothing much left in there holding steam back.
In a situation where a steam trap may have a small amount of wire drawn on the disk or seat and, if the condensate load is more than what the bleed though is, the trap will still operate but bleed through at the same them. It produces a subtle, high-pitched sound in the background blowing through, and we hear the trap operation correctly.
Focus on Air Leak Surveys
At DUMC we also employ our ultrasonic instrument to inspect for air leaks. With many noises in mechanical rooms competing for attention, it is crucial to focus exclusively on air leaks and have a general idea about the sounds we are looking for rather than worrying about clicks, pressure, and the rings slinging up and down inside the motor. It is like being in the woods. You see million of leaves, but more than likely you are going to focus on one particular tree. Of course, if we are using the Ultraprobe to look for air leaks and happen to walk past an electrical disconnects or motor starter and pick up electrical disturbances through the headphones, we note it and turn over the proper shop.
In the course of our control air survey’s we found hundreds of air leaks from pneumatic control devices that resulted in excessive air compressor run time. We are now in the process of going digital or replacing and repairing the leaking devices.
Our ultrasonic based steam and air maintenance program has been a resounding success. At Duke’s research facilities the steam savings in the first year was $250,799, which translates to 37 million pounds of steam saved when compared to the previous year. At Duke North Hospital we saved $141,670, a savings of 25 million pounds of steam.
Currently we are focusing our energy on duke Clinic, a very old building that has been patched together. Steam lines and traps were plastered in walls and we have no blueprints so it is very difficult to conduct a survey, which will probably take us two years to complete. It is a painstaking job, but well worth the effort.
The goal is to establish an ongoing predictive maintenance program. We are also very appreciative of our support from the North Carolina Department of Energy.
PUBLIC RELATIONS & MARKETING - Joe Coencas
507 Sixth Avenue, Brooklyn, NY 11215 (718) 965-1058
PUBLIC RELATIONS & MARKETING - Joe Coencas
507 Sixth Avenue, Brooklyn, NY 11215 (718) 965-1058
Lighting retrofits at the Seeley G. Mudd Medical Center Library reduce electric load
submitted by: Mike Herran, Manager Technical Systems
Light levels are customarily measured in foot candles ( = fc ). One Foot Candle equals the total intensity of light that falls upon a one square foot surface that is placed 1 foot away from a point source of light that equals 1 candle power.
Note: The term candela also refers to candle power, 1 candela = 1 candle power.
- Lower Lobby: Before 4-6 foot candles at reading chair; After 11-16fc
- Mezzanine: Before 18 fc; After 25 fc
- Suggestion box Lobby: Before 12 fc; After 15 fc
- Directory bench: Before 11 fc; After 17 fc
- IRB Drop Box: Before 13 fc; After 19 fc
- Reserve reading room rail: Before 3 fc; After 7 fc
- Center stairs: Before 19 fc; After 7 fc
- Table stairs: Before 19 fc; After 16 fc
- Elevator hall: Before 3 fc; After 13 fc Pat and Rick were also very pleased with their warm white 2700-Kelvin color selection.
Approximate projected annual total kWh saved is 251,986; Approximate total kW saved was 29.7. Approximate pay back period is 2.1 months. AC savings will be impressive although not part of the payback.
The incandescent lamps were in constant need of replacement; so much so that the lamp holders showed signs of wear due to frequent use.
- Stop buying incandescent lamps. They only last 700 hours maximum life & fail at much shorter intervals at higher temperatures.
- Start or continue using compact fluorescent lamps that last 10,000 hrs which use 20 to 30% of the energy & do the same job.
- Seek out other incandescent rich environments. Maybe a short training lecture for zone mechanics on compact fluorescent lamps?
- Encourage all DUMC employees, E&O, and others to take advantage of the slam-dunk savings these items will offer them.