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Show -10- COMBUSTION OF OFF-SPECIFICATION FUELS As indicated in the introduction, the range of fuels involved within this research theme has been relatively diverse, ranging from low calorific value gases to petroleum residues and in some instances relatively high ash coals. As may be seen from the Appendix, the number, of investigations is considerable and to attempt to summarise all the results is beyond the scope of this paper. For information within this theme, the reader is referred to the reports that are available; these are indicated in the appendix. A particular area which is worth noting in connection with the developing fuels, is that concerning the combustion of coal water slurries. This work commenced early in 1983 in collaboration with Hoogovens Groep BV, the Netherlands Iron and Steel Company in whose terrain, the Umuiden Research Station is situated. The object here was to review and test the possibilities of converting sinter bed ignition hood burners from coke oven gas firing to pulverised coal, transported either pneumatically or in water as a slurry. Within this investigation, combustion tests - H02 and H03 - were subcontracted to the IFRF [ 13 ]. The preliminary experience gained in this investigation in terms of handling the slurries and the important burner design aspects in relation to atomisers and quarl geometry, was an excellent basis for the execution of the subsequent investigations concerning coal water slurries CWS1 and CWS2. These investigations [ 14 ], funded by the Governments of the Netherlands and Canada concerned initially, burner design aspects for the production of stable, unsupported flames, in thermal boundary conditions representative of boilers designed for heavy fuel oil firing. For this work - CWS1 - the No. 2 semi-industrial scale furnace was used - see figure 9 - which when fired with a total thermal input of 2.5 MW, using a flexible experimental burner as shown in figure 10, gives combustion chamber firing densities in the |
