By-product Coke Oven Gas--By-product coke oven gas is a product of the destructive distillation of coal in a distilling or by-product coke oven. In this class 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