Auxiliary gas or coal fired grates must be installed to insure continuity in the operation of the boiler where the operation of the furnace is intermittent or where it may be desired to run the boiler with the primary furnace not in operation. Such grates are sometimes used continuously where the gases available are not sufficient to develop the required horse power from a given amount of heating surface.
Fear has at times been expressed that certain waste gases, such as those containing sulphur fumes, will have a deleterious action on the heating surface of the boiler. This feature has been carefully watched, however, and from plants in operation it would appear that in the absence of water or steam leaks within the setting, there is no such harmful action.
Fig. 32. Babcock & Wilcox Boiler Arranged for Utilizing Waste Heat from Open Hearth Furnace.
This Setting may be Modified to Take Care of Practically any Kind of Waste Gas
FOOTNOTES
[50] Temperatures are average over one cycle of operation and may vary widely as to maximum and minimum.
[51] Dependant upon length of kiln.