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Steam Injection Experiments in a Microturbine - a Thermodynamic Performance Analysis

par De Paepe, Ward ;Delattin, Frank;Bram, Svend;Contino, Francesco
Référence 3rd International Conference on Applied Energy(ICAE2011: Perugia, Italy), Proceedings of The 3rd International Conference on Applied Energy (ICAE2011)
Publication Publié, 2011

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Résumé :

This paper reports on a series of steam injection experiments on a Turbec T100 microturbine.Combined Heat and Power (CHP) systems, such as the considered T100 microturbine, use onesingle primary fuel to simultaneously produce electric and thermal power. In doing so, theyrealize significant energy savings when compared to conventional schemes of separatedproduction. However, a reduction in the demand for heat (like e.g. in summertime) will forcethis type of units to shutdown. This significantly reduces the amount of operating hours and hasa severe negative impact on the net present value of such CHP investment projects.The aim of this paper is to investigate and demonstrate the effects of steam injection in thecompressor outlet of a microturbine operating under reduced heat demand conditions, this tokeep the unit running. The necessary steam can be auto-raised with heat available in the turbineexhaust downstream of the recuperator. Such an injection will keep the unit running and thusavoid a forced shutdown. Furthermore it is expected that the electric efficiency will rise andthat the power production will become more economically viable as a result of the increase inoperating hours.This paper reports on the influence of steam injection on the electrical efficiency and shaftspeed of a T100 unit. ASPEN® simulations of the behaviour of the CHP unit are also presented.These simulations predicted a 2.2% rise in electric efficiency at nominal electrical output when5% of the mass flow rate of air is replaced by steam.The steam injection experiments resulted in stable runs of the unit, a predicted reduction inshaft speed and increased electrical efficiency. Validation of the ASPEN® simulations againstthe experimental data revealed the necessity for a more accurate determination of the air massflow rate and more precise compressor characteristics.