never been given the
attention that its importance merits. It is true that installations have
been made for the utilization of such gases, but in general they have
consisted simply in the placing of a given amount of boiler heating
surface in the path of the gases and those making the installations have
been satisfied with whatever power has been generated, no attention
being given to the proportioning of either the heating surface or the
gas passages to meet the peculiar characteristics of the particular
class of waste gas available. The Babcock & Wilcox Co. has recently gone
into the question of the utilization of what has been known as waste
heat with great thoroughness, and the results secured by their
installations with practically all operations yielding such gases are
eminently successful.

TABLE 52

TEMPERATURE OF WASTE GASES FROM
VARIOUS INDUSTRIAL PROCESSES

+-----------------------------------------------------+
|+-----------------------------------+---------------+|
||Waste Heat From |Temperature[50]||
|| | Degrees ||
|+-----------------------------------+---------------+|
||Brick Kilns | 2000-2300 ||
||Zinc Furnaces | 2000-2300 ||
||Copper Matte Reverberatory Furnaces| 2000-2200 ||
||Beehive Coke Ovens | 1800-2000 ||
||Cement Kilns | 1200-1600[51]||
||Nickel Refining Furnaces | 1500-1750 ||
||Open Hearth Steel Furnaces | 1100-1400 ||
|+-----------------------------------+---------------+|
+-----------------------------------------------------+

The power that can be obtained from waste gases depends upon their
temperature and weight, and both of these factors vary widely in
different commercial operations. Table 52 gives a list of certain
processes yielding waste gases the heat of which is available for the
generation of steam and the approximate temperature of such gases. It
should be understood that the temperatures in the table are the average
of the range of a complete cycle of the operation and that the minimum
and maximum temperatures may vary largely from the figures given.

The maximum available horse power that may be secured from such gases is
represented by the formula:

W(T-t)s
H. P. = ------- (23)
33,479

Where W = the weight of g