OCR Text |
Show dependence so that each of the processes considered in this section is dependent on the local temperature and thus on the thermodynamic properties of the fuel. Operational and Durability The characteristics involved in the operational and durability group themselves have only a secondary effect on the combustion process, but can have a greater impact on the -overall suitability of a fuel for a given industrial burner application. Thermal and oxidative stability, for example, refers to the tendency exhibited by some multicomponent fuels to undergo irreversible changes in species composition and certain physical properties during storage. While not completely understood, the mechanisms which lead to these problems are dependent on the composition of the fuel and, in particular, the trace metal content and acidity of the fuel. Fouling and corrosion characteristics also are defined by the fuel composition. It might also be noted, from Table 1, that the fuel property characteristics that impact operational and durability considerations (in particular sediment and trace metals content) also affect emissions characteristics of the fuel. What this review demonstrates is that fuel composition data is a basic requirement for any serious attempt at fuel combustion characteristics determination. The lack of detailed determination of the fuel composition in combustion experiments introduces a needless and unquantifiable uncertainty into the analysis of the experimental results. Fuel composition determination should be required data produced as part of any investigation of combustion characteristics. This need is particularly acute with respect to multicomponent liquid fuels whose composition can change during a test series because of evaporation or thermal and oxidative instabilities. A second major requirement for a fuels effects data base is knowledge of the chemical kinetic rates that apply to the fuel decomposition and combustion processes. This rate information is central to any detailed combustion analysis and, indeed, to the interpretation of combustion experiments. Other key data includes gas and liquid phase physical properties and thermodynamic data. These data are relevant to specific combustion processes, and their importance in a given application depends on - the -influence of the specific combustion process which they affect in a given industrial burner configuration. Nevertheless, in a generalized alternative fuels data base, data on gas and liquid phase physical properties and fuel thermodynamic properties should be included. 1.2.9 |