Abstract:
Summary
Integrated gasification combined cycle (IGCC) systems, which utilize coal,
petroleum coke, heavy oil, biomass and waste materials as a feedstock,
continue to enter the power generation market. The gasification products
from gasifiers using these feedstocks are mixtures of hydrogen, carbon
monoxide and inerts like nitrogen, carbon dioxide and water. These
mixtures are then used as a fuel in low-emission power generation
applications. Unlike natural gas or methane, which has been widely used
and researched for many years, these mixtures have not been widely
investigated. Thus the aim of this study is to provide data on the
combustion properties of syngas mixtures, mainly focusing on laminar
burning velocities and critical strain rates to extinction. These combustion
properties data are essential for gas turbine combustor modelling using
turbulent burning velocity closure models.
The establishment of such a database in this study mainly relies on
numerical computations. Therefore, the experimental campaign was
limited to investigation of several CO/H2/N2 fuel mixtures fuel mixtures at
different equivalence ratios and operating conditions. The laminar burning
velocity values, obtained from the experimental campaign were used
mainly for validation of the chemical kinetics model and reaction
mechanism.
The principal outcome from this study is that at ambient conditions and
reactant preheat temperatures up to 400K experimental laminar burning
velocity values compare well with numerical predictions. The laminar
burning velocity tests at high pressure presented a number of
complications due to the formation of cellular flames and the flow in theburner tube entering the transitional laminar to turbulent regime. As a
result the numerical model could not be fully validated experimentally for
high pressure conditions.
A comprehensive combustion properties database has been created using
numerical simulations, based on comprehensive descriptions of the
chemical kinetics and extensions using neural networks.
CFD simulations of reacting flows in a practical combustor geometry
demonstrated the importance of obtaining accurate laminar burning
velocities and critical strain rates to extinction data.