| OCR Text |
Show Carbon in Primary Grit/Carryover With overfeed firing, and, to a lesser extent, with travelling grate firing, grit carryover, collection and refiring to standards which can meet emission legislation, requires consideration at design stage. Pot furnace techniques, which relate to what happens on the grate and immediately above it, can give only a limited indication of primary carryover - i.e. the grit which is "measured" by the relationship between ash missing from the grate at the end of a test and the ash content of the collected grit. Such a measurement can give broad relative indications of grit collection requirements. We also intend to determine the reactivity of the grit by means of a Burning Profile test to obtain an indication of how well it will burn when refired. It will be appreciated, however, that the time separation of the pot furnace technique is not truly suited to investigating the problems of grit emission, collection and refiring. Maximum Grate Temperatures Thermocouples peened to the grate surface enable these temperatures to measured and if necessary warnings about unduly high temperatures can be given to design engineers with indications of any alleviation techniques. Undergrate Air Pressure This is invariably measured during pot furnace testing and gives a useful guide to fan performance specification data. The compartment pressures for optimum combustion air distribution on large travelling grate stokers can be predicted. From the foregoing it will be gathered that the pot furnace evaluation programmes for the prediction of stoker performance provide design engineers with comprehensive data about fuel combustion capabilities. Over the course of about 10 years to 1955 some 100 fuels, ranging from peat to anthracite, from at least 20 different countries 24-15 |
