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Show BACKGROUND In the mid-seventies C-E began to explore ways to reduce the use of gas and oil as ignition, warm-up, and stabilizing fuels in pulverized coal-fired utility boilers. At the same time many of our utility customers began to encounter boiler load limitations because of insufficient pulverizer capacity. This capacity limitation was the result of lower grade (i.e., higher ash) coals they were beginning to receive as many mining operations moved to increase their yield. The above problems were compounded by the changing role of coal-fired units from the traditional base-loaded mode to that of cycling or two-shifting modes. In the past, a utility's generating system consisted typically of base-loaded coal-fired units, cycling oil-fired boilers, and peaking gas turbines. In recent years nuclear units have been absorbing the base load capacity and oil-fired units are being replaced with coal-fired units. This means that coal-fired units, in some cases, are responding to cycling or peaking loads, which places heavy demands on supplemental oil and gas systems to support these types of operation. To resolve both the problem of deteriorating coal quality and increases in auxiliary fuel use brought about by cyclic operation, C-E has developed a method of using coal, rather than oil or gas, for the functions of unit startup and low-load stabilization. The system, termed Direct Ignition of Pulverized Coal (DIPC) uses a unique high-energy electric arc to ignite a dense phase stream of coal. The DIPC firing assemblies can therefore replace oil or gas equipment used to supply stabilizing fuel in pulverized coal-fired boilers. The DIPC system offers the following advantages for utility boilers: - Eliminates the need of oil or gas during the ignition and warm-up periods from either cold or hot start conditions. - Provides stability of main coal flames at low loads and effectively extends the turndown on coal to an almost infinite range. 11-3 |