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11:20   Parallel Session: Operational Experience II
Chair: Ennio Macchi
20 mins
L.Y. Bronicki
Abstract: Rankine Cycle Plant Designs for Waste Heat Recovery L.Y. Bronicki Ormat Technologies, Inc. e-mail: bronickily@ormat.com ABSTRACT This paper summarizes experience in developing cycles, configurations and equipment for electricity generation from low grade waste heat. Theoretical investigation and practical applications in the past are briefly presented and referenced. Applications of this technology (which matured mainly in geothermal applications), to the recovery of exhaust heat of simple cycle gas turbines driving compressors on gas pipelines, gas processing plants, cement and glass industries are presented. Many pilot plants were constructed generally operating for a relatively short time, such as in Raft River Idaho and Heber Binary in California. In the last 20 years, four manufacturers brought the Organic Rankine Cycle (ORC) to maturity assuring a reasonable life span in the geothermal energy utilization, the companies include: Barber Nichols in the U.S., Ben Holt in the U.S., Turboden of Italy and ORMAT. Ormat has manufactured about 100 MW in capacities ranging from 200 kW to 20 MW of Waste Heat recovery ORC plants and about 1200MW for geothermal applications in capacities from 200 kW to 130 MW. Most of the compressor stations have a capacity below 50 MW and operate basically unattended. The complexity and the necessity of an operator prevents the use of bottoming steam systems (combined cycle) on this size of plant. Hydrocarbons condense at higher pressure than steam. This feature mitigates the need for vacuum maintenance. Most of these plants are air-cooled, thus enhancing sustainability in addition to reducing the environmental impact. In these applications, which are mainly retrofits, the ease of ORC operation make its use possible where steam turbines were unsuccessful. Supplied oil temperature to the OEC is between 160°C to 200°C and the return temperature is 90°C. Power generation from waste Heat is also applicable to other industries such as glass and cement manufacturing. For example, at the Heidelberg's Cement Plant, Lengfurt, Germany, waste heat from the clinker cooler is recovered in a heat exchanger after the precipitator. Under these operating conditions 8.2 MW of heat is transferred from the clinker cooler waste air flow to the thermal oil circuit and fed into the ORC facility connected behind, where it is used as a heat source. Under the operating conditions, some 1.3 MW of 50 Hz electric power is generated. Many commercial plant applications will be presented in the applications mentioned above, cycle parameters and operational results are also included. REFERENCES [1] Bronicki, L.Y., 1981, “Energy Recovery from Waste Heat by Organic Rankine Cycle Turbogenerators”, Institute of Marine Engineers, London [2] Peppink, G., 1984, “Integration of an ORC in a steam and gas turbine unit (Stag unit) with and without facilities for district heating”, Proceedings of the International VDI-Seminar, Zurich [3] Bronicki, L.Y., 1984, “Twenty Five Years of Experience with Organic Working Fluids in Turbomachinery”, ORC-HP Technology Conference, Verein Deutscher Ingenieure, Zurich [4] Legmann, Hilel, 1999, Power Returns from Waste Heat, International Cement Review [5] Bronicki, L.Y., 2002, “Geothermal Power Stations”, Encyclopedia of Physical Science and Technology, Third Editions, 6, Academic Press, San Diego [6] DiPippo, R., 2004, “Second Law Assessment of Binary Plants Generating Power from Los-Temperature Geothermal Fluids”, Geothermics, University of Massachusetts, Dartmouth, USA [7] Nasir, P., and Jones S., 2004, “Turning Recovered Heat to Power”, PipeLine and Gas Technology, June 2004 [8] Bronicki, L.Y., 2005, “Bottoming Organic Cycle for Gas Turbines”, Proceedings of GT2005, ASME Turbo Expo 2005, Power for Land, Sea and Air, June 6-9, 2005 [9] Engle, D., 2008, “From Waste Heat to Power”, The Journal for Onsite Power Solutions, Jan. 2008
20 mins
Asaf Mendelovitz
Abstract: Organic Rankine Cycle for Solar Applications Asaf Mendelovitz Ormat Technologies, Inc. e-mail: amendelovitz@ormat.com ABSTRACT The presentation describes the characteristics of experimental solar-powered units ranging from 600W to 5 MW. A historical perspective is given of piston engines of the 1940s and sealed 600 W turbo generator-driven pumps in Africa. In the 1980s, three solar pond-powered Organic Rankine Cycle (ORC) power plants were built providing 150, 70 and 5000kW. One of the ORC systems operated for 15 years in Texas. Details of the 5 MW ORC with a solar pond will be presented. The turbo generator itself displayed conversion efficiency in terms of the input and output temperature to the turbine, over 60% of the Carnot limit. With the actual condensing temperature at 30°C of this installation, the thermo-dynamic conversion efficiency was 5.7%. The Bureau of Reclamation Solar Pond Power Plant, consisting of a 70 kW Ormat Organic Rankine Power system, generated power from a 3000 sq m. solar pond. In 1986, it was installed in El Paso, Texas and operated for 14 years. The program addressed control of salinity, to generate power and produce fresh water in Western United States. In 2005, a 1.5MW (gross) ORC was supplied to Arizona Public Service (APS), powered by a Parabolic Trough. This project demonstrated the ease of operation and, in addition, an early start of operation thanks to the low cut-off of the system. The combination of the highly reliable and low maintenance ORC units coupled with a 160-400°C thermal fluid temperature solar collectors, is cost-effective for power plants up to 10 MWe. Another promising path for this technology is the combination of the solar ORC with a simple biomass backup boiler allowing an “all renewable solar-biomass” package. The system can be operated with or without heat storage. Technical details and operating parameters will be presented for the aforementioned applications. REFERENCES [1] Tabor, H., and Bronicki, L.Y., 1961 “Turbine for Small Solar Power Package”, UN Conference, New Sources of Energy, Rome. [2] Bronicki, L.Y., 1972, “The Ormat Rankine Power Unit”, IECEC, San Diego, USA [3] Bronicki, L.Y., 1981, “A Solar Pond Power Plant”, IEEE Spectrum, February 1981 [4] Bronicki, L.Y., 1984, “Twenty Five Years of Experience with Organic Working Fluids in Turbomachinery”, ORC-HP Technology Conference, Verein Deutscher Ingenieure, Zurich [5] Fisher, U., Sugermen, H., Ring, A., 2003, Solar Operated ORC for 1 to 5 MW Grid Connected Systems, Proceedings ISES Solar World Congress 2003 Goteborg ,Sweden [6] Bronicki, L.Y., 2008, “Ormat Rankine Cycle Configurations for Utilization of Low Temperature Heat Sources”, Proceedings of the 9th Biennial ASME Conference on Engineering Systems Design and Analysis ESDA08
20 mins
Ron Conry, Sankar Mohan, Randolph Dietzel, Joost Brasz
Abstract: Verdicorp, a company focusing on next generation green technologies (www.verdicorp.com), has completed the development of an oil-free ORC turbine as a derivative of the award-winning, high-volume Danfoss-Turbocor direct-drive centrifugal HFC134a refrigeration compressor and is in the final phase of product qualification of its first three models with turbine output powers of 50, 60 and 75 kWel. The turbine is designed for low temperature heat source ORC applications. The fluid section of the turbine consists of a single-stage radial-inflow turbine using HFC245fa as its working medium. The remainder of the machine contains - just like the Danfoss Turbocor compressor - a set of active magnetic bearings, a high-speed (up to 45,000 rpm) direct-drive permanent magnet generator and a power module that converts the high-frequency power of the generator to the regional 50/60 Hz line frequency at 380/400/460/575V to satisfy local grid requirements. Turbine, generator, bearings, power conversion and control are all integrated in a single hermetically sealed unit, cooled internally by the working fluid, resulting in a very compact design. The variable-speed operation of the unit allows variation of the turbine speed to adjust for differences in available head/pressure ratio as a result of changes in ambient heat sink temperatures. The inverter section of the turbine allows grid-independent island operation of the ORC system. Prototype testing at actual operating conditions has started April 2010 and was successfully completed late last year. A number of field trial units are currently running at beta sites. Field trial qualification will be completed later this year. The similarity of this turbine with its high-volume compressor relative and their shared manufacturing base guarantees excellent product quality, favorable product cost and easy product volume ramp-up rates when needed which are important features for future market penetration. For any further request, please contact Sankar Mohan at sankar.mohan@verdicorp.com. REFERENCES 1. Brasz, J.J., Transforming a Centrifugal Compressor into a Radial Inflow Turbine, paper C060 presented at the 17th International Compressor Engineering Conference at Purdue, West Lafayette, Indiana, July 12-15, 2004 2. Brasz, J.J., Waste Heat Power Recovery using Air Conditioning Hardware, DKV-Tagungsbericht 2004, Bremen 17-19 November 2004, Band II.2 pp. 75-82, 2004
20 mins
Jean Gropper
Abstract: Small Organic Rankine Cycle Power Units for Remote Unattended Applications Jean Gropper Ormat Technologies, Inc. e-mail: jgropper@ormat.com ABSTRACT Over the last 40 years, the development of backbone telecommunications systems and construction of strategic oil and gas pipelines has spanned tens of thousands of kilometers in harsh environments (arctic to tropical, unmanned or developing areas). As the vast majority of these areas are off grid, the need arose for a highly reliable and maintenance-free power supply to allow the continuous operations of these projects. The objectives for high reliability in telecommunications, cathodic protection and SCADA systems in strategic projects have become very demanding and the problems faced by power systems designers in areas not serviced by commercial power are very stringent. This since power generators must operate continuously on a 24-hour-per-day, 365-days-per-year basis. Modern solid state electronic equipment require relatively low power (from a few hundred watts to 4 kW) but stringent requirements for power supply: high reliability, long life (20 years+) and low maintenance. Conventional diesel generators were not adequate. Intensive research followed in the development and application of sophisticated energy converters with attention directed to practical units. Two technologies emerged: the Thermoelectric Generator (TEG) and the Organic Rankine Cycle-based Closed Cycle Vapour Turbine Generator (CCVT). Both are widely used TEG bellow 1 kW and CCVT from 600 W to 4 kW. PV systems were introduced lately but are hindered by vandalism and stealing (unattended sites). And, Fuel Cells have too short a life, at least for now. To achieve long life and avoid mechanical and thermal stress, it was necessary to develop a heat engine that would operate at comparatively low temperatures (below 200°C). To accommodate these low temperatures and small sizes, it was decided to design a prime mover, based on a Rankine cycle, specifically for the applications in mind. A turbine rather than a reciprocating engine was chosen and steam was replaced by other working fluids selected and tested for stability. In 1966, after work on process fluid lubricated bearings and hermetically sealed systems, the first hermetically sealed solar and fuel operated systems operated and have since been followed by some 3000 fuel-operated units. These CCVT have logged more than 40 million field operational hours, many units have been in operation for more than 35 years without overhaul demonstrating a MTBF of 300 000 hours for the turbogenerator itself. Characteristic of this class of ORC will be presented as well as case histories and key criteria for selecting remote, unattended power solutions. REFERENCES [1] Bronicki, L. Y. 1972, – “The Ormat Rankine Power Unit”, 7th Intersociety Energy Conversion Engineering Conference, page 327 – 334 (1972) [2] Bronicki, L.Y., 1988, – “Experience with High Speed Rankine Cycle Turbomachinery” – Conference on High Speed Technology, 1988, Lappeenranta Technical University, Finland [3] Gropper, J., 2002, “Closed Cycle Vapor Turbines and Hybrid Systems, 24th Annual International Telecommunications Energy Conference, Montreal, 2002 [4] Frichtl, W., 1997, “Two Decades of Security Along TransAlaska Pipeline”, PipeLine & Gas Journal, July 1997