The ovens are arranged in two groups or batteries of 50 ovens each. Each oven is an air tight retort, consisting of a rectangular chamber 43 feet 6 inches long, 17 inches wide and 6 feet 6 inches high. The ovens are placed side by side and are supported on a steel struc ture, consisting of light I-beams, running the length of the battery, which rest on cross gir ders supported by steel columns. The constru. tion allows the brick work to be inspected at all points. The primary object, however, is the uniform distribution of fuel gas to the com bustion chambers for heating the oven retorts. The retorts are separated by hollow walls, which are divided into 10 compartments, each compartment containing four, preferably vertical, flues. Alongside this chamber, and directly un der the vertical flues, are 10 combustion cham bers. The gas supply to each of the chambers is controlled independently, and a uniform heat is maintained throughout the entire length of the oven. The air for combustion is admitted through an opening in the wall between the air and combustion chambers. The air is heated to 1800°. F. by a pair of regenerators, placed together under the centre of the battery and running its entire length. A vertical flue conducts the air from the regenerator to the air-chamber under the oven.
The well-known Siemens principle is used in operating the air generators, with reversals every 30 minutes. The fuel gas is reversed at the same time as the air by means of a suitable valve; but the gas is not regenerated. The gas unites with the hot air in five combustion cham bers, ascends through the vertical flues to a horizontal flue above, through which it passes and descends through the five chambers in the other end of the oven, thence through the air chamber and vertical flue connection to the regenerator, and through the reversing valves to the stack. The regenerators are built entirely independent of the oven structure, so that their expansion does not affect the oven brickwork.
Coal Handling.— A steel coal storage bin of a capacily equivalent to about two days' coal consumption is placed between the batteries. The coal is elevated to the bin from a hopper placed under the coal receiving track, by a belt or other type of conveyor. A coal larry of eight tons' capacity runs on a track on the top of the batteries and under the coal bin. The larry consists of a long narrow bin with eight spouts in the bottom through which the coal is run into the oven retort through holes in the top of it and is leveled by means of a bar worked through a small opening in the doors at the ends of the oven. The larry is operated by an electric motor and receives its load of coal from the storage bin, under which it passes. A very dense metallurgical coke can be produced, and the output of an oven largely increased by com pressing the coal into a mold slightly smaller than the retort and charging the mass through the oven door.
Coke Handling.— Upon the completion of the coking process, the oven doors are raised and the mass of six tons of coke is pushed upon a movable platform by means of a ram. The pushing ram, as well as the machine on which it is mounted, are operated by electric motors. The coke after being pushed upon the platform is quenched with a spray of water and allowed to cool. The platform is then tilted by an elec tric motor, and the coke slides off into cars, which run on a tracic at the back of the machine. At some ovens the coke is discharged into cars and there quenched, or the cars are run off to a quenching station.
Gas Mains.—The gas distilled from the coal during the colcing process is conducted to the condensing house by two independent sys tems of mains. These mains run on top of the battery the entire length— one on each side. Each oven is connected to each main by a vertical pipe and valve. During the first part of the process, the rich gas is taken off through the rich gas main. The valve to this main is then closed and the balance of the gas is taken off through the poor gas main. When the cok ing is completed, the valve to the poor gas main is closed, disconnecting the oven from both mains.
Condensing Plant.— The gas leaving the coke ovens is divided into two fractions, viz., the first fraction of ((rich° gas, which is sent out as illuminating gas, and the second fraction or ((poor') gas, which is used for heating the ovens. The cooling of the gas and the removal of the tar and ammonia are done in the usual apparatus, hence it is not necessary to discuss it here in detail. Both the rich and poor gases are treated in the same manner.
The rich gas when freed of tar and ammonia leaves the condensing plant and passes into the purifying plant, and from there into a large gas holder for illuminating gas, from which it goes into the city. The poor gas, after being treated in the same manner as the rich gas, leaves the ammonia washers and passes through two ben zol scrubbers. Here it is mixed with producer gas, when necessary, and carried to the ovens for heating.
The tar oil by which the gas is washed runs first from a tank through the second benzol scrubber into another tank. From here it is supplied by a pump into the first benzol scrub ber. The tar-oil enters the tank with about 5 per cent of benzol, and finally leaves the washer with about 15 per cent of benzol. It is col lected in another tank. From here it is fed by a pump into a still, in which the benzol is re duced again to about 5 per cent. The exhausted oil collects in another tank. From here it is taken by a pump through the oil cooler in order to be again supplied to a tank for a new ab sorption of benzol.