ABSTRACT
The chemical compositions of fossil fuels mainly consist of carbon, hydrogen, nitrogen, sulfur, oxygen, and
other trace elements. When fossil fuels are combusted with an adequate amount of oxygen, the carbon is converted to carbon dioxide, the hydrogen is converted to water, the nitrogen partly forms nitrogen oxides, the sulfur is converted into sulfur dioxide, and the oxygen reacts with the carbon, sulfur, and hydrogen in the fuels to reduce the amount of oxygen to be supplied. Thus, we have
C O CO2 2+ →
2H O 2H O2 2 2+ →
N O 2NO2 2+ →
N 2O 2NO2 2 2+ →
S O SO2 2+ →
Y.-P. Zhang
CONTENTS
8.1 Introduction ................................................................................................................................................................... 137 8.2 Combustion Reactions ................................................................................................................................................. 138
8.2.1 Enthalpy of Formation of a Compound ......................................................................................................... 138 8.2.2 Reaction Enthalpy ............................................................................................................................................. 139 8.2.3 Reaction Rate ..................................................................................................................................................... 142
8.3 Gaseous Fuels ................................................................................................................................................................ 143 8.3.1 Properties ........................................................................................................................................................... 143 8.3.2 Ignition ............................................................................................................................................................... 143
8.4 Liquid Fuels ................................................................................................................................................................... 146 8.4.1 Chemical Composition ..................................................................................................................................... 147 8.4.2 Physical Properties ........................................................................................................................................... 147 8.4.3 Vaporization and Combustion ........................................................................................................................ 150 8.4.4 Several Points on Synthetic Fuels ................................................................................................................... 151
8.5 Solid Fuels ...................................................................................................................................................................... 151 8.5.1 Properties of Coals ............................................................................................................................................ 151 8.5.2 Properties of Wastes ......................................................................................................................................... 152 8.5.3 Devolatilization and Combustion .................................................................................................................. 152 8.5.4 Integrated Coal Gasification Cycle with an ASU ......................................................................................... 156
References ................................................................................................................................................................................ 158
These are the primary combustion products when fossil fuels are burned in a high-temperature furnace. Reactions of carbon and hydrogen with oxygen provide a high-temperature process with heat. Nitrogen and sulfur, however, react with oxygen to form undesired nitrogen oxide and sulfur oxide compounds. Inorganic minerals and some organic compounds will generate fly-ash (particulate) and other organic materials in the flue gases if solid fuels are involved in the combustion.
