| Advanced Boiler Case Study An article by Tucson Medical Center (Click HERE to download) |
| TUCSON MEDICAL CENTER HEALTHCARE 5301 E. Grant Road, Tucson, Arizona 85712, U.S.A. Internet: www.tmcaz.com February, 2003 Tucson Medical Center (TMC) is a community hospital with 673 licensed acute and psychiatric beds and 90 bassinets, serving the Tucson metropolitan area, Southern Arizona and northern Sonora, Mexico. The hospital is situated on 300 acres (1.21 km2) in the heart of Tucson and consists of over 1 million sq.ft. (92,900 m2) of single-story construction, making it the largest single-story hospital in the United States. Heating, cooling and steam utilities are distributed from a central plant. TMC is identified as one of the top 20 largest customers of Tucson Electric Power Co. (TEP) and is one of the largest customers for Southwest Gas (SWG) in the Tucson area. Electrical and gas utility consumption occurs primarily in the central plant. TMC Plant Services Department is constantly looking for opportunities to reduce operating expenses by limiting energy costs and optimizing energy use. TMC and TEP have participated in several projects, which have provided benefits for each. Lighting and motor retrofits, co-generation and thermal energy storage are several projects which provide equipment and systems that improve the operation at TMC and reduce the demands on production for TEP. TMC was in the process of engineering and budgeting for replacement of two 600HP/6MW Ygnis boilers installed in 1978 and decided to partner with TEP and International Combustion Systems (ICS) on the project. ICS is startup company holding US patent rights for the Warga boiler and disposes with certified production facilities for boiler manufacturing and testing. The partnership was solidified and the boiler replacement project was initiated in 1998. TMC was to provide most of the installation and access for monitoring; TEP would provide engineering and construction oversight; and ICS was to provide three new steam boilers that would be the first of their kind installed with serial numbers 001, 002 and 003. TMC and TEP representatives, in December 1998, ran a test firing, performed at the ASME certified factory in Slovenia. March, June and November of 1999, saw the start up of three 400HP/4MW Warga steam boilers providing 120-psi/8.3 bar steam for use in the central plant and throughout the hospital. Many differing benefits were expected by the parties involved with the project. Success of the project would be determined by attaining 15% improvement in boiler seasonal Input/Output efficiency. Monitoring has verified this goal has been exceeded with a minimum 20.5% increase in efficiency (up to 15 percentage points), or so much less fuel used for same amount of steam generated, respectively, compared with old installation, although efficiency, as displayed by flue gas analyzer, improved marginally. Many issues arose concerning new design techniques, certificates of operation, importation, local jurisdictions and operations. All issues were addressed as the project progressed through design, construction and commissioning. The unique boiler design technique provided by Dr. Z. Warga, incorporating minimal number of tubes, cooled door, absence of refractory and maximum furnace heat exchange surfaces providing improved turn down efficiencies along with Autoflame combustion controls and Weishaupt burners has proven to be effective for the project at TMC. A method of accurately estimating payback and life cycle costs during the design phase was useful when justifying the project. Verifying the accuracy of the predicted improvements, Rosemount monitoring equipment, provides a sense of satisfaction that the project exceeds expectations for reduced operational expenses through the improved efficiencies of our boiler plant. Richard Prevallet Director of Facilities |
| Tucson Medical Center, aerial image |
| CONTRACT REPORT TUCSON MEDICAL CENTER, ARIZONA, U.S.A. Tucson Medical Center in Arizona, USA (TMC) is one of the best-managed hospitals in the USA (lowest cost per unit of area). It is also one of the best equipped serving an urban area of more than 750,000 including supplying medical services to Tucson based USA Air Force base, which is the largest in the world with over 6,500 aircraft. In 1999 TMC replaced its old boiler installation consisting of two well maintained 6MW / 600HP fire-tube Ygnis type boilers, installed in 1978, with three new 4MW / 400 HP boilers. The new boilers were put into operation in March, June and August of 1999. The seasonal efficiency of the new boiler system improved minimum 20.5% (up to 15 percentage points), or so much fuel less used for same amount of steam generated, although combustion efficiency, as displayed by flue gas analyzer, improved marginally. Savings were initially estimated to provide an 8-year payback, with fuel prices as of 1997, if new conventional boilers would be installed. Actual fuel savings led to sub 3 year payback, with fuel prices as of 2000, according to official figures provided by TMC using state of the art Rosemount computerized monitoring equipment. With economizers the savings would further improve efficiency cutting another minimum 6 months from the payback. Savings will continue to rise with fuel prices and usage. New boilers, with serial numbers 001, 002 and 003, were the first of their kind installed. They were designed in Slovenia by Dr. Z. Warga and his team and manufactured by mioMETAL, an ASME certified plant with H, S and U stamps, located in Maribor, Slovenia. Additional benefits for this installation, besides high tech combustion controls and burner, include high technology brand new fire-tube boiler design providing following unique benefits to industry: a) minimum number of tubes (just 75 while conventional same-sized units have up to 237); b) no refractory; c) cooled door design meeting all criteria applicable for the first time on steam boilers, as well as on double furnace units; d) no efficiency degradation at reduced boiler load, turn downs, respectively, which is where all boilers operate most of the time although they have to be designed for peak load; e) absence of tube sheet cracking due to significantly lowered temperature on tubesheet as result of cooled door and increased furnace; g) common platform eliminating various models and providing significant simplifications in manufacturing process; f) retrofit of installed boilers possible. Equipment List: Combustion control: Autoflame MK5 complete with EGA system for 3 parameter trim (CO2, O2, CO) and exhaust gas monitoring Boilers: Fire-Tube Warga Type, power rating 4MW / 400HP (6TPH) 10 bar / 150 psi Burners: Weishaupt Dual Fuel RGL 60/2-A Autoflame Engineering Ltd., Unit 19 Bellingham Trading Estate Franthorne Way, Bellingham, London, SE5 3BX Internet: www.autoflame.com |
| ADVANCED FIRE-TUBE BOILER TECHNOLOGY |
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