Engineer Case Studies
TekWorx Optimization Control Makes the Most of Condensing Boiler Plant Design of NYC High-Rise
Innovative Automatic Breach Control Valve Protects
New World Trade Center Buildings
School District Boiler Retrofit
Boiler Plant Efficiency Improvement for Housing Complex
Award-Winning New Laboratory Project
Electric to Hydronic Boiler Conversion for Landmark Times Square Building
Unique “Immersion Burner” Boiler Design for Federal Agency
High-Efficiency Central Chiller Plant for Medical Center
Piping Freeze Protection for Cooling Tower
Water Detection System Protects Datacenter
Rugged Snow-Melting Solution for Truck Ramp
Buddhist Temple Maintains Comfort with Floorwarming System
Equipment Protection Tracetek in NYCTA Rail Control Center
TekWorx Optimization Control Makes the Most of Condensing Boiler Plant Design of NYC High-Rise
A TekWorx Control & Energy Optimization (CEO) System does the thinking for the unique heating and domestic hot water system designed for a building completed in 2005.
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Innovative Automatic Breach Control Valve Protects New World Trade Center Buildings
At the earliest stages of the rebuilding effort from 9/11, G.A. Fleet received a call from Mr. Bob Benazzi of Jaros Baum & Bolles. Mr. Benazzi was working on the fire protection systems for the new WTC buildings and had some progressive ideas.
Mr. Benazzi raised the following concern: a breach in any of the 6" fire protection risers would quickly deplete their water supply. Mr. Benazzi suggested installing a self-contained control valve in each riser that would close in the event of a breach. Mr. Kari Oksanen, General Manager at Singer Valve, was determined to come up with a solution. He was able to work up a design and sent Mr. Benazzi a conceptual drawing by the next day. Singer Valve built and tested the valve the following week, with favorable results.
The next step was to demonstrate the operation of the valve for Jaros Baum & Bolles. Rich Mullen, VP and Manager of Fleet Pump and Service, devised a thorough test setup, utilizing the 1000 gallon pump test pit at his facility. During the demonstration Mr. Mullen explained the operation of the valve and tested the valve in various scenarios. Next, Mr. Benazzi wanted to demonstrate the operation of the valve (which now incorporated his proposed design) for the approval of the New York City Fire Department (NYCFD) and The New York City Department of Buildings (NYCDOB). Satisfied with the results, Mr. Benazzi told us it was time to take the next step and set up a testing for Underwriters Laboratory (UL). The testing went well with the valve operating flawlessly within close tolerances.
Installation in the first of the new buildings, 7 World Trade Center, has been completed with the valves installed as planned. The building engineers have been testing the valves once a month and are very happy with the results. The outstanding participation and effort by the individuals at Singer Valve Company was the key to a successful resolution for this client.
School District Boiler Retrofit
For this performance contract retrofit project, GA Fleet helped a Long Island, NY school district update 11 schools with 41 AERCO boilers.
AERCO boilers provide heat during 95% of the heating season. Peak load is augmented with cast-iron dual-fuel boilers. An energy management system controls boiler firing rate for maximum system efficiency. Hot water temperatures are reset from 180 to 100 degrees for maximum efficiency; hot water pumps operate on VFDs to vary flow in response to changes in building load. AERCO boilers operate properly without primary pumps, isolation valves, or other flow.
Project Update: 2006
Since the original contract work was completed in 1997, the school district has built a 200,000 sq ft middle school and a 350,000 sq ft high school. In both of these schools the newer, larger AERCO BMK-2.0 boilers were specified by the school district, and are used year round for both heat and domestic hot water.
Beyond the high efficiency provided by the AERCO boilers, the school district takes advantage of an Interruptible Gas rate, further reducing their fuel costs. In this case the alternate fuel is Propane-Air, an all-gas alternate fuel solution that allows the use of high efficiency gas-fired equipment, rather than lower efficiency oil-fired equipment. The propane air system consists of a buried propane tank, with a vaporizer mixer (shown) and fully automatic controls and safety features.
The propane air system was supplied by GA Fleet and is fully integrated into the district's EMS system.
Boiler Plant Efficiency Improvement for Housing Complex
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Boiler room shown before and after. |
This 50-acre Queens, NY housing complex called for the retrofit of 11 circa 1950 #6 oil-fired firetube boiler rooms with 60 high-efficiency gas fired boilers. Each boiler plant provides heat and domestic hot water to several garden apartment buildings. An energy cost study completed by the consulting engineer indicated a 250% improvement in overall boiler plant efficiency.
Award-Winning New Laboratory Project
This project in a newly constructed laboratory building uses a 2,000,000 BTUH boiler plant to provide low temperature heating water. Boiler controls communicate with Johnson Controls BMS to vary HW reset temperatures from 130 to 80 degrees for maximum efficiency. This project won the Governors Award for design.
Electric to Hydronic Boiler Conversion for Landmark Times Square Building
This retrofit project was for a landmark building in the Times Square area. The 6,000,000 BTUH boiler plant provides heat for this electric to hydronic system conversion. Sidewall venting required due to lack of chimney in building. Boiler controls communicate with Johnson Controls BMS to vary HWS reset temperatures from 180 to 100 degrees to provide optimum heating system control and maximum efficiency.
Unique “Immersion Burner” Boiler Design for Federal Agency
G.A. Fleet designed a heating plant for a federal agency regional headquarters. Low NOx emissions (under 50 PPM, standard), minimum footprint, high thermal efficiency (85%), simplicity of operation (no modulation or linkages) and virtually no maintenance (no refractory) are notable features of this design.
High-Efficiency Central Chiller Plant for Medical Center
This project called for a new central chiller plant for a major NYC medical center. Large horizontal split case pumps, a pre-fabricated secondary chilled water VFD package, and the plate and frame heat exchanger (for free-cooling) were specified and provided by G.A. Fleet. SCHW VFD controls include advanced logic for sequencing 300 HP pumps with the highest wire-to-water efficiency.
Horizontal split case pumps for condenser water. These pumps were selected specifically for their extremely low NPSHR (under 14 ft), since the cooling tower was located only one floor above the pump level.
Installation of horizontal split case pump showing proper installation of a single pressure gage with isolation valves for suction and discharge connections. This installation is recommended to eliminate the loss of calibration over time when using separate gauges for reading suction and discharge pressure.
This pre-fabricated, pre-engineered Secondary Chilled Water VFD and control system operates the (3) 300 HP SCHW pumps. Each VFD includes soft-start bypass. The control logic operates the SCHW system at the lowest possible energy consumption using wire-to-water efficiency analysis. H-O-A switches are provided for simple operator control in the event of electronic control failure.
The plate and frame heat exchanger is utilized for free cooling operation. In this cooling mode the refrigeration and dehumidification requirements of the medical center are met without mechanical cooling (chillers) by rejecting the CHW heat gain through the cooling tower. Plate type heat exchangers are ideal for this application due to the large surface area in a small footprint, allowing a close approach temperature between the hot and cold circuits.
Piping Freeze Protection for Cooling Tower
This downtown NYC financial district building requires year-round cooling tower operation. A sophisticated powerline-based monitor and control system was selected by the consulting engineer to be the most cost-effective method to protect the piping from freezing and to monitor the pipe temperatures. Forty-five remote temperature transmitters are located at every pipe location that could contain standing (non-circulating) water, based on valve positions or pump operation. All monitoring is performed without any wiring, other than power to the heater cables.
Mission critical 24/7 cooling in this financial district building requires operating cooling towers and external water piping as large as 24" in the winter. Any pipe or valve freeze-up (and burst) would be catastrophic, so a fully-supervised system of monitoring and controlling heat tracing was specified.
Distributed pipe temperature sensing was determined to be the most accurate method of verification that pipes were not in danger of freezing. A patented powerline-based heat trace monitor and control system was determined the most cost effective method of providing distributed pipe temperature monitoring. Sensors were placed in the worst-case locations, namely between each isolation valve and the corresponding pipe connections to the cooling towers. Based on valve position and pump operation, these remote locations could contain non-circulating water, which is most likely to freeze.
Remote temperature sensors (the black junction boxes) are fully addressable, self-diagnostic, and “ruggedized” for industrial, transit, and low temperature/high vibrtion installations.
A modular control and monitor panel is provided to monitor the 5000 feet of heater cable and 45 temperature sensors. The spread-spectrum powerline communication technology utilized does not require filters or isolation transmitters, making it ideal for existing and retrofit applications. The only wiring required for this system is the power feed to the heater cables. All monitoring occurs over these wires.
Water Detection System Protects Datacenter
Real-world conditions, even in "clean" datacenters require rugged sensor cables, built from 100% non-corroding materials, and equipped with low profile connectors for ease of maintenance. Leak detection systems are often operating for years before a leak occurs. There is only one chance for early detection and location. After 20 years of development and improvements, the Patented Tracetek system is still the most accurate and reliable leak detecting and locating system.
This typical under raised floor sensor cable installation illustrates why only the most durable sensor cable (orange wire by stanchion running below datacom wiring) should be used. Conduits, copper grounding wires, and telecom wiring bundles cross over the sensor cables in many locations. The Tracetek sensor cable is insensitive to pressure and kinking, and can be provided with low profile connectors for ease of future removal for cleaning.
This example of the contamination present in a "clean" datacenter illustrates why only non-metallic, non-corroding materials must be utilized in the sensor cable. Only Tracetek uses conductive polymeric construction and insulation, exposing no metal to the environment to corrode.
Rugged Snow-Melting Solution for Truck Ramp
The most rugged, flexible, cut-to-length heater cables were selected for this industrial facility truck ramp. The ability to withstand vibration from commercial trucks, salt and other corrosive chemicals, and thermal expansion of the ramp assures heater cable life that will exceed that of the concrete ramp.
Cables are easily attached directly to rebar. A 2-stage pour is not required. Cable reels of 1000 feet each are provided and cut to length in the field. Field conditions often require modifications in cable lengths and layout from the original engineering design.
Heater cable power connections and terminations are above grade in accessible junction boxes. Only the rugged polyolefin jacket of the cable is in the slab. Rakes, shovels, and stone will not damage the heater cable. There are no buried splices that can fail due to poor manufacturing, handling, or galvanic corrosion.
Buddhist Temple Maintains Comfort with Floorwarming System
This Buddhist temple utilized over 11,000 feet of floorwarming cable to maintain carpet surface temperatures of 80 degrees for the comfort of its members. Finite element heat transfer models were generated by Raychem to design the floorwarming system with as little heater cable as possible. First floor heater cables were imbedded in the floor slab, second floor heater cables were located on the underside of the second floor slab.
Cables are installed prior to topping concrete pour. Cable reels of 1000 feet each are provided and cut to length in the field. Field conditions often require modifications in cable lengths and layout from engineering design.
Heater cable power connections and terminations are above grade in accessible junction boxes. Only the rugged polyolefin jacket of the cable is in the slab. There are no buried splices that can fail due to poor manufacturing, handling, or galvanic corrosion.
Custom made floor temperature sensing thermostats provide an additional level of control for comfort and energy savings. Capillary tubing of up to 50 foot lengths allow temperatures to be monitored in the center of the room(s). Installation in thermally conductive fluid-filled conduit provides rapid response and the ability for removal for future service.
Equipment Protection Tracetek in NYCTA Rail Control Center
The NYCTA's recently completed Rail Control Center, located in midtown Manhattan, is the central nervous system for the entire NYCTA rail system.
Miles of Raychem Tracetek water detection cables are located throughout the facilities raised floors. In the event of water leaks from piping, foundations, or other sources, the networked Tracetek alarm modules instantly report the presence of water, and the location, accurate to 1 foot, along the length of the cable.
HVAC High Efficiency Plate Frame Heat Exchangers
High efficiency plate frame heat exchangers are frequently utilized to isolate open from closed piping systems, and to provide pressure breaks in high-rise applications. Working pressures up to 400 PSIG are frequently required.
These three identical units are installed at 5 TIMES SQUARE in New York City. Provided with 10" reversing valves to insure high operating efficiency and reduce maintenance, the units have been in continuous operation since the building was put into service.
The Pumps that Went to College
This upgrade earns an A+ for eliminating clogs and saving energy.
By Jane Alexander
Set among 1,100 lush, wooded acres on the affluent north shore of Long Island, NY the campus of Stony Brook University bustles daily with approximately 20,000 students. Located 65 miles east of New York City, this SUNY College in the village of Stony Brook has grown tremendously during the 44 years since its founding. Students arrive each year from 50 states and 80 foreign countries.
The once quaint, idyllic college is now recognized as one of the nation's leading centers of learning and scholarship-fulfilling the mandate given by the New York State Board of Regents in 1960 to become a university that would "stand with the finest in the country." Identified as a Type I Research University by the Carnegie Foundation-the highest classification and a distinction granted to fewer than 2% of all colleges and universities nationwide-Stony Brook joins the ranks of such institutions as Harvard, Yale, Johns Hopkins, Princeton, and Stanford as the newest addition to the 63 members of the Association of American Universities (AAU). Stony Brook offers 119 undergraduate majors and minors, and 102 Masters, 40 Doctoral, and 31 Graduate Certificate programs.
Out of Sight, Out of Mind (But Not for Long)
Not surprisingly, as the university's academic reputation had grown, its enrollment had been swelling and its facilities multiplying at such a vigorous rate, that parts of the campus infrastructure had not kept pace. As often happens with both public and private institutions during periods of rapid growth, systems that are not visible can easily be overlooked or moved to a "deferred maintenance" list. In this case, one of the more notable systems to fall off the radar screen was the lift station that pumps the school's wastewater to its treatment plant. The results of this oversight were neither pretty, nor cheap!
As a matter of fact, the pumps in the Stony Brook Lift Station used to clog so frequently that crews for Suffolk County Department of Public Works (SCDPW) came to anticipate such an event as part of their weekly routine, recalls Ron Warren, Maintenance Director of the Division of Sanitation, Operations & Maintenance.
"The clogging became quite predictable," he says. "Every week to 10 days we'd have to go out there and free an impeller that had become jammed with rags or some other debris."
The problem-prone 3-MGD facility is just one of 87 pump stations and 24 wastewater treatment plants maintained by the Department. Built years ago, when the campus was smaller and generated less flow, the station and its original equipment simply couldn't keep up with the demands placed on it by the much larger university center and three outlying areas that comprise the Stony Brook of today. Although it would appear that the station's three, 60-HP pumps had ample capacity; the size of these units and their variable speed drives defininitely contributed to the clogging problem during low flow periods (which is most of the day).
Unfortunately, the problems that the SCDPW faced at the Stony Brook lift station are shared by many organizations that are responsible for similar stations equipped with large, variable speed pumps.
Searching for A Workable Solution
The Stony Brook station was designed with a 20,000-gallon wetwell and three 60-HP end-suction pumps mounted horizontally in the dry pit. Approximately two years ago, when the pumps were clogging as often as twice a week, SCDPW asked G.A. Fleet Associates, Inc., an engineering consulting group and manufacturer's rep, based in Harrison, NY, to recommend a workable solution that SCDPW's own engineering staff and crews could implement.
"Clogging is a problem we typically encounter when dealing with large, older pumps with variable speed drives," explains Mark Cavanagh, Service Sales Engineer with G.A. Fleet. "It was common practice in the past to oversize pumps, but that resulted in a unit running at minimum speed most of the day. Low-velocity flow contributes to rags and other material getting entangled on conventional impellers and eventually clogging the pumps. An oversized pump also demands a wasteful amount of energy."
After reviewing the original specifications and spending several months monitoring the station's flow, Fleet recommended replacing all three existing units with N-Pumps from ITT Flygt. This new type of pump has an innovative self-cleaning impeller incorporating a volute with a special relief groove that prevents rags, high-fibrous material, grease or solids from clogging the pump. The Fleet team based its recommendations on the results of tests at other installations where fouled impellers had been a recurring problem. During those tests, the N-pumps not only operated for extended periods without becoming clogged, they also achieved dramatic energy savings.
Figure 1. One of Stony Brook's three newly installed ITT Flygt N-Pumps.
G. A. Fleet further recommended changing the sizes of the three pumps to a combination of two, 60-HP Flygt Model NZ3300 pumps to handle peak flows (Figure 1), and a Base-Load pump to handle the low-flow conditions (See Sidebar). Instead of a third 60-HP unit, however, the Base-Load pump Fleet specified was a 20-HP Model NZ3152 model that would help reduce the station's energy consumption. Additional upgrades included a Flygt MultiTrode® Liquid Level Control System, a conductivity probe-based system that is fully compatible with SCDPW's new SCADA system, which operates on Citex software. According to Ron Warren, as a first step towards a full-blown, continuously monitored operation, SCDPW plans to add more MultiTrode systems and gradually network eight stations with SCADA.
Lessons Learned
One doesn't have to be a math major to calculate the return on investment for this successful project.
Today, over a year later, Stony Brook's Base-Load pumping system continues to run as designed-smoothly and efficiently. While G.A. Fleet Associates and the engineers and maintenance crews from SCDPW may not have been sitting in on any classes, they clearly earned an A+ for their teamwork on this particular college project!
For more information on the application and products referenced in this article, please contact: G.A. Fleet Associates 914-835-4000
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