Title:
A Study on the Combustion of Biomass Based Ethanol Co-Fired to Natural Gas
Author(s):
Braun-Unkhoff, M., Dembowski, J., Herzler, J., Karle, J., Naumann, C., Riedel, U.
Document(s):
Paper
Abstract:
Currently, it is discussed to which extent future energy demands can be satisfied by alternative and renewable fuels (biomass and by-products) to meet challenges such as reduction of greenhouse gas (GHG) emissions and ensuring security of supply at affordable prices. New concepts for electric power generation are required, including centralized and decentralized approaches, to address the foreseen worldwide increase of electrical power demand. Among the centralized approaches, the concepts of co-firing or the operation of gas turbines with a combined gasification plant (IGCC), need to be re-investigated, focusing on their potential on using alternative fuels. The use of biomass in small local facilities with low power range (decentralized approach) offers an efficient, CO2-neutral and environmental friendly production of electrical energy and heat. The coupling of thermal gasifiers or bio gas reactors with fuel-flexible micro gas turbines, with substantially lower emissions of pollutants, allows the efficient use of biomass in these facilities. Alcohols have a high potential to serve as alternative fuels. Ethanol can be produced from renewable sources that contain starch, sugar, or cellulose, mostly by fermenting sugar or by converting starch, from very common crops, e.g. sugar cane, sugar beet waste, molasses, corn, and corn cabs. In the last years, the use of ethanol for power generation is also discussed, in addition to its role within the transport sector: Burning in gas turbines, decentralized (micro gas turbines) or centralized (power plants), neat or co-fired with liquid fuel (diesel or kerosene) or gaseous fuels (natural gas or biogas). However, new concepts and new unconventional fuels require a re-investigation, of the burner and the gas turbine itself, to ensure a safe operation and a maximum range in tolerating variations of fuel composition and conditions. Chemical kinetic modeling has become an important tool for interpreting and understanding the combustion phenomena observed and also for their prediction. This strategy requires the availability of a validated reaction scheme appropriate for the parameter range of interest (fuel, temperature, pressure, fuel-air ratio). However, the predictive capability of the detailed reaction mechanism used in simulations must be validated by relevant experimental data. In the present work, the description of the oxidation of pure ethanol as well as of different shares with natural gas will be investigated focusing on two major combustion properties: (i) ignition delay times measured in a shock tube, at different pressures, for stoichiometric and lean mixtures and (ii) laminar flame speed data, mostly gathered from literature. Comparisons between measured and predicted data – by exploiting several chemical kinetic reaction mechanisms, from literature and including an in-house one – are presented. The results are discussed with respect to the combustion behavior of natural gas.
Keywords:
alternative fuel, combustion, ethanol, laminar flame speed, natural gas, reaction model, ignition
Topic:
Biomass Conversion Technologies for Intermediates, Liquid and Gaseous Fuels, Chemicals and Materials
Subtopic:
Synthetic biofuels
Event:
22nd European Biomass Conference and Exhibition
Session:
3CV.2.64
Pages:
1236 - 1243
ISBN:
978-88-89407-52-3
Paper DOI:
10.5071/22ndEUBCE2014-3CV.2.64
Price:
FREE
