Abstract
As part of the general program of investigations by the ASME Special Research Committee on Furnace Performance Factors, the Combustion Research Section of the Bureau of Mines is making a series of determinations of furnace heat absorption of representative pulverized-coal-fired boiler furnaces. During the course of these studies, modifications have been made in the test technique to improve the precision of furnace testing. Automatic recording instruments have been employed, which permit more detailed sampling and examination of furnace-outlet gases than heretofore, without an appreciable increase in the time or work required. Improved designs of radiation shields have been developed for high-velocity thermocouples with accuracy comparable to the B&W multiple-shield high-velocity thermocouple, but which may be employed conveniently in pulverized-coal-fired furnaces. Detailed descriptions are presented of the distribution of gas composition and temperature at the outlet of a 640,000-lb per hr horizontally fired boiler furnace. Based upon this knowledge, the sampling characteristics of the gases at the furnace outlet for furnace heat-absorption measurements have been examined, and a procedure is suggested for the rational selection of simplified sampling schedules. The methods of calculating furnace heat absorption from the temperature and gas-composition data are examined critically with special emphasis on the effect of weighting with respect to mass velocity. Suggestions are presented whereby the significance of mass velocity for furnace heat-absorption calculations may be determined from the temperature and gas-composition data.
