COKE-OVENS. The coke-ovens in use in the United States are almost exclusively of the old beehive type, 101 ft. to 12 ft. in diameter and 5 ft. to 7 ft. in height. It is recognized that they are very wasteful, a large proportion of the value of the coal used being lost, but no attempt to recover this seems to have been generally made in this country. In 1857 there were in operation in the United States, in 279 establishments, 26,001 ovens, and 3.594 ovens in course of construction. These ovens consumed 11.859,753 tons of coal, producing 7.611,705 tons of coke, a pereentage of 64-2. Dr. Bruno Terne, in a paper read before the Chemical Section of the Franklin Institute. October 20, 1891, estimates that on the basis of the work at two large establishments in France there should also have been saved 151,804,838 lbs. of sulphate of ammonia, or 12.8 lbs. per ton of coal, which. at 3 cents per lb., would have been worth $4,554.746. besides a large quantity of tar, amounting probably to nearly 24, per cent of the weight of the coal. In England and on the Continent great progress has been made in the introduction of improved ovens for the recovery of these by-products, and many different kinds of ovens, designed for this purpose, have come into use.
The tardiness of the coke manufacturers of the United States in introducing improved ovens is inexplicable, as the flames from the tops of the beehive ovens which illumine the sky by night in the Conuellsville region are a constant reminder of the present wasteful methods of coke manufacture. The greater first cost of the improved ovens is undoubtedly one of the reasons which has delayed their introduction, and it is also feared that, although the coke made by them may be of good quality, there may be a prejudice against it. as it lacks the sil very appearance of the Connellsville coke. The Hon. Carroll D. Wright. United States Com missioner of Labor Statistics, in his report, " Cost of Production Iron, Steel. Coal. etc." (1890), gives the average cost of producing one ton of coke in 30 establishments in the United States as follows: coal, $1.219; labor, $0.357; officials and clerks, $0.028: supplies and repair?, $0.058; taxes, $0.005: total, $1.667. The average amount of coal necessary to make one ton (2.0(10 lbs.) of coke was :3,110 lbs. With these figures the results obtained with the improved ovens described in the following paragraphs may be compared: The Coppee Coke-Oven., which is extensively in use in Europe, is designed for coking finely divided coal. They are usually built in series of :30 or 40, and are worked in pairs. The ovens, which are 30 ft. long, 18 in. wide, and 4 ft. high, have each 28 vertical flues lead ing from the top through the common to two ovens, to horizontal flues that pass longitudinally beneath the chambers. In these horizontal flues the gases from a freshly
charged oven mix with those from one in which the coking is nearly complete, and combustion is effected by air admitted through three small openings. At each end of the oven are two iron doors. When a charge is completely coked, it is pushed out of the oven through the doors at one end by an engine and ram placed at the opposite end, this operation requiring about two minutes. The lower doors are then closed, and a fresh charge of coal fed in through three holes in the roof, which are covered by sliding doors. The charge is next leveled by means of rakes, the doors closed, and the operation resumed ; the whole time, from opening the doors to discharge to closing them after a being but eight minutes. The coking occupies 24 hours, and the ovens are charged alternately at 12-hour intervals.
The Simon-Carves coke-Oven (Figs. 1 to 4), which is designed to save the by-products from coking, is somewhat similar in construction to the CoppCue. There are charging-holes, a, a', a', in the roof of the oven, which is from 2 ft. to 2,1 ft. wide and 54 ft. to 61 ft. high. The gases are drawn off through a pipe, b. b', b", which is provided with a regulating valve, whence they pass into a system of tuities common to from 30 to 50 ovens, kept cool by jets of water, in which the tar and ammo niaeal liquors are con densed. The lower open end of the condensing pipes clip into a collector for the products of condensation, similar to those employed in gas-works. The gases from the condenser are then passed through scrubbers filled with wet coke, where the last traces of ammonia are moved. The uncondensed gases pass onward to the oven for heating purposes, entering through a horizon tal aperture, c, in the basal flue of the oven above a grate. d, that is filled with ignited coke-dust, while the air for combustion enters from below through the grate. Under the base of the oven the burning gases pass to and fro once, then rise between two adjacent ovens to the uppermost of the e, e' e", and pass grad ually downward to a large flue. f, which conveys them to the chimney. The duration of the coking is front GO to 72 hours, in ovens of the smaller size. The yield of coke is said to be 75 per cent. At the iron-works, in France, in 1879, 46,902 tons of coal were coked in 85 ovens of this type. The amount of coke produced was 32,092 tons, or per cent, together with 1,096 tons of tar per cent) and 4.3399 tons of ammoniacal liquor. The net gain, after deducting all expenses, and not counting the coke, was $18,9:38. The consumption of on the grate did not exceed 35 lbs. per ton of coke produced.