NATURAL GAS IN FURNACES.
A paper describing the use of natural gas in the puddling furnaces at Leechburg, Pa., was presented by Mr. A. L. Holley to the American Institute of Mining Engineers. This well is about twenty miles northeast of Pittsburg, on one of the side tributaries of the Alleghany river. It had been drilled in search of oil to a depth of 1,250 feet in 1871, but none was found. A great flow of gas was developed, however, accompanied by a slight spray of salt water, and this has continued with little or no diminution to the present time. The gas in its escape has been discharged through a five-inch pipe, and at a pressure of from sixty to eighty pounds per square inch. The rolling mill of Messrs. Roger & Burchfield is on the opposite side of the river, and it has been for some years devoted to the production of fine grades of sheet iron from charcoal pig metal, by puddling and in knobbling fires. The usual weekly product of the mill has been thirty tons of No. 3 tin plates and fifty tons of No. 24 to twenty-eight sheets.
The well was bought by this firm for $1,000, and the gas is led across the river, a distance of 500 feet, through a three-inch pipe. It is distributed through half-inch pipes, and at a pressure of about forty-five pounds per square inch, to several of the furnaces. No essential alteration in any of the furnaces has been found necessary in the use of the gas fuel, except to brick up the fire bridge and to put in the gas and air pipes. The old grate used for coal is loosely covered with bricks and cinder, so that a slight percolation of air may take place through them. The gas is admitted through a half-inch pipe, and blows toward the fire-bridge through eighteen or twenty one-eighth inch jets. The air is blown in, at about 2 lbs. pressure, through two one and one-eighth-inch jets, obliquely down upon the centre of the hearth, and a very perfect combustion is obtained. A great improvement is effected in the quality of the product of the puddling furnaces by the combined action of the gas and air blast. The air is blown in during the melting, but it is then shut off until the boiling begins. It is then turned on full, and a violent boiling action is maintained without any rabbling. Many advantages result from the use of this fuel. The product of the mill has increased about thirty per cent., from sixty to seventy tons of coal are saved daily, besides the labor necessary to fire with it, and a poorer quality of iron can be used in making the tin plate. Thus the iron now used is credited to the furnace at $45 per ton, while charcoal blooms have cost $80. These are certainly enormous advantages, and though every mill cannot have a permanent gas well, it must be more economical to produce such results by making coal into gas than to continue using it in the solid form. The gas at Leechburg is used in fourteen furnaces and under seven boilers. Its composition is carbonic acid, 0.35; carbonic oxide, 0.26; illuminating hydrocarbons, 0.56; hydrogen, 4.79; marsh gas, C H4, 89.65; ethyl hydride, C2 H6, 4.39; specific gravity, 0.558. This analysis shows about 57 per cent. of carbon and 42 per cent. of hydrogen. If the well discharges one million cubic feet of gas daily, it would weigh about sixty tons, yielding thirty-nine tons of carbon. Mr. Holley calculates that it equals about 150 tons of bituminous coal, such as is found in the Pittsburg region.