Bozza, Pio (2017) DEVELOPMENT OF A FUEL FLEXIBLE, HIGH EFFICIENCY COMBUSTION UNIT. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Lingua: English
Title: DEVELOPMENT OF A FUEL FLEXIBLE, HIGH EFFICIENCY COMBUSTION UNIT
Creators:
CreatorsEmail
Bozza, Piopio.bozza@gmail.com
Date: 11 December 2017
Number of Pages: 135
Institution: Università degli Studi di Napoli Federico II
Department: dep08
Dottorato: phd038
Ciclo di dottorato: 30
Coordinatore del Corso di dottorato:
nomeemail
Mensitieri, Giuseppegiuseppe.mensitieri@unina.it
Tutor:
nomeemail
Cavaliere, AntonioUNSPECIFIED
Date: 11 December 2017
Number of Pages: 135
Uncontrolled Keywords: Cyclonic burner; MILD combustion; Fuel Flexibility; Low emissions; Thermal Power;
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/25 - Impianti chimici
Date Deposited: 06 Jan 2018 03:18
Last Modified: 19 Mar 2019 11:59
URI: http://www.fedoa.unina.it/id/eprint/12213

Abstract

The present work is aimed to develop a fuel flexible small-scale burner (1 - 10 kW) with high performance in terms of energy saving and pollutant reduction. In this study the design, manufacturing and testing of a lab scale burner operated in highly diluted combustion processes, also known as MILD combustion, have been carried out. Firstly, a cyclonic flow-field configuration was chosen as the most valuable design solution because it allows to operate with very strong internal recirculation levels of the burned gases. This implies modest and uniform (no hot spots) temperatures, thus ensuring a significant reduction of pollutant emissions, while providing for long mixture residence times in small size systems to insure complete conversion. Then, the Laboratory Unit CYclonic flow-field (LUCY) burner has been constructed and tested. The cyclonic flow has been achieved by two pairs of oxidant/fuel jets that feed the combustion chamber in an anti-symmetric configuration thus realizing a centripetal cyclonic flow field with a top-central gas outlet. Autoignition and stabilization of distributed combustion regimes have been proved to occur when a sufficient entrainment of hot species in the fresh oxidant and fuel jets, by means of an efficient turbulent mixing, is reached. The cyclonic burner has been designed to operate by varying the external operational parameters (inlet temperature of the main flow, equivalence ratio, external dilution of the mixture, residence time, nominal thermal power), which can be varied independently each other allowing to investigate a wide range of operative conditions. Experimental campaigns has been performed in order to define the operational conditions which the cyclonic burner can stably operate in MILD combustion. In particular, it was possible to identify different working regimes of the system (No Combustion, Low Reactivity and Stable Combustion) and thus the operative conditions corresponding to stable working regime. Moreover, during the experimental campaigns it has been observed a hysteresis behavior of the system that allows to stabilize the process operating two different procedures, thus extending the operative range of the system. Then, a characterization of LUCY burner in terms of pollutants emission have been carried out and the main operational characteristics of the cyclonic combustion burner were investigated. Temperature measurements inside the chamber and gas sampling analysis were carried out in order to evaluate the operability range of the cyclonic burner and its performance. It has been demonstrated that MILD Combustion can be achieved in a wide range of operating conditions and the lowering of the working temperatures inside the combustion chamber allows to obtain very low NOx and CO emissions in a whole range explored. Finally, experimental campaigns have been operated in order to verify the performance of LUCY burner and to optimize it in terms of low pollutants emission in the usual working conditions by varying the nominal thermal power, without external preheating and external dilution. In particular, slightly fuel-lean conditions seem to be the optimal working point in order to minimize CO and NOx, simultaneously. Furthermore, it has been showed that it is possible to achieve a complete fuel conversion and low pollutant emissions for nominal thermal powers up to 10 kW. Such condition ensures very good performance in terms of stable working conditions of the cyclonic burner, thermal efficiency and eco-compatibility. It has been shown that the cyclonic burner is fuel flexible, stable and efficient in a wide range of operative conditions.

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