| Abstrakt: |
The high temperature ORC of Triogen was originally designed to utilize exhaust heat from landfill gas engines. Now more than 40 plants are operational, it is worthwhile to have a look at the different applications, and how lessons learned can lead to a new design. Giving the working fluid and the design of the evaporator, heat source temperature may vary between 350 and 530 °C. At the heat rejection side, sometimes a useful heat sink other than the ambient may be utilized at a higher temperature, of course penalizing power and efficiency. The various heat sources applied will be described. Engines fueled by various fuels from bio-oil from pig fat to gas from landfills, mines and digesters were seen as heat source, but also flue gas from the combustion of various kinds of biomass. All these led to a variety of heat source temperatures and flue gas compositions, where problems like slagging, fouling or abrasive wear of evaporator surfaces had to be met. Various schemes in terms of number of engines feeding one or more ORC plants were build. Condenser heat was sometimes used for heating or drying purposes. Each situation required a specific solution for applying the mostly standard ORC plant. These solutions involved the flue gas systems (including provisions for metering flue gas flows), evaporators and heat rejection systems. Within the standard ORC module, the only variable is the turbine nozzle, for optimization of performance pending heat input and back-pressure based on condenser condition. This paper will describe how optimal solutions were arrived at. An overview will be given of installed plants, mentioning their specific demands and how these were met. Operational experience will be reported on in terms of availability, and how the current level of availability was arrived at by careful following the learning curve. Finally a new concept plant design will be presented, which takes care of all lessons learned. [ABSTRACT FROM AUTHOR] |
