Effects of solar hybridization on the performance of a gas turbine

Homann, Christiaan (2015-12)

Thesis (MEng)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: This study investigates the effect of the solarization of a gas turbine on its performance and details the integration of this gas turbine into a solar power plant. A Rover 1S/60 gas turbine (Rover, 1966), rated at 45 kW, was modelled in Flownex and validated against a one-dimensional thermodynamic model, at design input conditions. The model of the gas turbine was adapted to incorporate different components of a CSP plant. The solar hybrid gas turbine (SHGT) model simulates the gas turbine performance when subjected to a typical variation in solar resource. A newly designed compressor for the Rover 1S/60 was integrated, both into the original Rover gas turbine model, as well as the SHGT model. Heat addition due to solar irradiation resulted in a decreased fuel consumption rate and an increased thermal efficiency for the gas turbine. The net power output of the turbine, however, decreased as the solar irradiation increased. This is a consequence of the additional pressure drop over the solar receiver, directly affecting the power produced by the turbine. Results showed that installation of the new compressor could eliminate the adverse pressure effects of the solar components, if implemented. To aid future experimental work, an interconnection component to direct air out of the Rover gas turbine into the solar receiver, was designed. The velocity and pressure profiles at two potential outlets from the main air casing were inspected by means of CFD simulations. The flow domain in the gas turbine was extracted, by reverse engineering the casing and relevant components. The inlet boundary conditions were adapted to evaluate both the original and the newly designed compressor. Results at the combustor inlet (outlet 1), implementing the original compressor, compared relatively well to experimental test data. It was found, however, that the flow should rather be redirected to outlet 2 which is a previous modification made to the casing to implement a recuperator. The velocity and pressure flow profiles were more uniform at outlet 2, even when implementing the new compressor. Two conceptual designs reintroducing the flow into the combustor were evaluated. The chosen concept significantly simplifies the implementation process by replacing the combustion chamber with in-line firing duct burners. To determine whether SHGTs are feasible on a commercial scale, four industrial gas turbines were investigated. The aperture area required to achieve sufficient heat flux in the solar receiver, in order to replace the thermal energy from combustion, was determined and compared to commercial CSP tower plants, with similar power producing capabilities. Scalability of the gas turbines proved competitive, but the eventual success will depend on future improvements in pressurised air receivers.

AFRIKAANSE OPSOMMING: Die studie wat volg ondersoek die effek van sonkrag-aanpassings op die werkverrigting van ‘n gasturbine en beskryf die integrasie van ‘n gasturbine in ‘n sonkragstasie. ‘n 45 kW Rover 1S/60 gasturbine is in die vloeinetwerkkode, Flownex, gemodelleer en is teenoor ‘n eendimensionele termodinamiese model by ontwerp invoer toestande gevalideer. Die gasturbine model is aangepas om verskillende komponente van ‘n konsentrerende sonkrag (KSK) stasie, soos ‘n son-ontvanger en heliostaatveld, te inkorporeer. Die aangepaste sonkrag gasturbine (SHGT) model simuleer die gasturbine werkverrigtinge wanneer dit aan ‘n tipiese variasie in son hulpbronne blootgestel word. ‘n Nuut-ontwerpte kompressor vir die Rover 1S/60 is in beide die oorspronklike Rover gasturbine-model en die SHGT model geïntegreer. Warmte toevoeging weens sonbestraling het gelei tot ‘n afname in die brandstofverbruiks tempo en ‘n verhoogde termiese doeltreffendheid van die gasturbine. Die netto krag van die gasturbine het egter gedaal met die toenemende bydrae van sonkrag. Dit is as gevolg van die addisionele drukval oor die sonontvanger, wat veroorsaak dat die krag wat deur die turbine geproduseer word afneem. Resultate het getoon dat die nuwe kompressor, indien geïmplementeer, die nadelige druk effekte van die sonkrag-komponente kan kanselleer. ‘n Komponent om lug uit die Rover gasturbine na die son-ontvanger te herlei, is ondersoek om toekomstige eksperimentele werk te steun. Die snelheids- en drukprofiele op twee potensiële uitlaatplekke vanuit die hoof lugomhulsel is deur middel van CFD simulasies geïnspekteer. Die vloeiprofiel deur die gasturbine is verkry deur terugwaartse-ontwikkeling van die omhulsel en relevante komponente. Die inlaat randvoorvaardes is aangepas om beide die oorspronklike en nuut-ontwerpte kompressor te evalueer. Die resultate by die inlaat van die verbrandingsruim (uitlaat 1), gegewe die oorpronklike kompressor, vergelyk goed met die eksperimentele toets data. Daar is egter bevind dat die vloei eerder na uitlaat 2, ‘n vorige aanpassing aan die omhulsel om ‘n hitte-uitruiler te implementeer, herlei moet word. Die snelheid en druk vloei profiele is meer eenvormig by uitlaat 2, ook met die implementering van die nuwe kompressor. Twee ontwerpe, wat die vloei in die verbrandingsruim herinvoer, is konseptueel geëvalueer. Die gekose konsep vereenvoudig die implementering van die proses aansienlik, deur die verbrandingskamer met in-lyn afvoer buis-branders te vervang. Laastens is vier industriële gasturbines ondersoek om te bepaal of SHGT’s uitvoerbaar is op 'n kommersiële skaal. Die heliostaat oppervlaktes wat nodig is om voldoende hittevloed in die son-ontvangers te bereik, om sodoende die termiese energie van verbranding te vervang, is bepaal. Daarna is die oppervlaktes met dié van kommersiële KSK-toring stasies, met soortgelyke krag vervaardiging vermoëns, vergelyk. Die skaalbaarheid van die gas turbines blyk om mededingend te wees, maar die sukses daarvan is afhanklik van aansienlike verbeterings in die doeltreffendheid van saamgeperste-lug ontvangers.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/97928
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