of apparatus the gases, instead of being burned at
the point of their origin, as in a beehive or retort coke oven, are
taken from the oven through an uptake pipe, cooled and yield as
by-products tar, ammonia, illuminating and fuel gas. A certain portion
of the gas product is burned in the ovens and the remainder used or sold
for illuminating or fuel purposes, the methods of utilizing the gas
varying with plant operation and locality.

Table 51 gives the analyses and heat value of certain samples of
by-product coke oven gas utilized for fuel purposes.

This gas is nearer to natural gas in its heat value than is blast
furnace gas, and in general the remarks as to the proper methods of
burning natural gas and the features to be followed in furnace design
hold as well for by-product coke oven gas.

TABLE 51

TYPICAL ANALYSES OF BY-PRODUCT
COKE OVEN GAS

+----------------------------------------------+
|+------+-------------------------------------+|
||CO_{2}| O |CO |CH_{4}| H | N |B.t.u. per||
|| | | | | | |Cubic Foot||
|+------+-----+---+------+----+----+----------+|
|| 0.75 |Trace|6.0|28.15 |53.0|12.1| 505 ||
|| 2.00 |Trace|3.2|18.80 |57.2|18.0| 399 ||
|| 3.20 | 0.4 |6.3|29.60 |41.6|16.1| 551 ||
|| 0.80 | 1.6 |4.9|28.40 |54.2|10.1| 460 ||
|+------+-----+---+------+----+----+----------+|
+----------------------------------------------+

The essential difference in burning the two fuels is the pressure under
which it reaches the gas burner. Where this is ordinarily from 4 to 8
ounces in the case of natural gas, it is approximately 4 inches of water
in the case of by-product coke oven gas. This necessitates the use of
larger gas openings in the burners for the latter class of fuel than for
the former.

By-product coke oven gas comes to the burners saturated with moisture
and provision should be made for the blowing out of water of
condensation. This gas too, carries a large proportion of tar and
hydrocarbons which form a deposit in the burners and provision should be
made for cleaning this out. This is best accomplished by an attachment
which permits the blowing out of the burners by steam.

UTILIZATION OF WASTE HEAT

While it has been long recognized that the reclamation of heat from the
waste gases of various industrial processes would lead to a great saving
in fuel and labor, the problem has, until recently,