The degree of superheat produced by a superheater placed within the boiler setting will vary according to the class of fuel used, the form of furnace, the condition of the fire and the rate at which the boiler is being operated. This is necessarily true of any superheater swept by the main body of the products of combustion and is a fact that should be appreciated by the prospective user of superheated steam. With a properly designed superheater, however, such fluctuations would not be excessive, provided the boilers are properly operated. As a matter of fact the point to be guarded against in the use of superheated steam is that a maximum should not be exceeded. While, as stated, there may be a considerable fluctuation in the temperature of the steam as delivered from individual superheaters, where there are a number of boilers on a line the temperature of the combined flow of steam in the main will be found to be practically a constant, resulting from the offsetting of various furnace conditions of one boiler by another.
[Pg 146]
8400 Horse-power Installation of Babcock & Wilcox Boilers and Superheaters at the Butler Street Plant of the Georgia Railway and Power Co., Atlanta, Ga. This Company Operates a Total of 15,200 Horse Power of Babcock & Wilcox Boilers
FOOTNOTES
[20] See pages [125] to [127].
[21] The actual specific heat at a particular temperature and pressure is that corresponding to a change of one degree one way or the other and differs considerably from the average value for the particular temperature and pressure given in [the table]. The mean values given in [the table] give correct results when employed to determine the factor of evaporation whereas the actual values at the particular temperatures and pressures would not.