STOVES. HOT-BEAST. During the past ten years a marked improvement has been made in blast-furnace practice in the universal introduction in a rge furnaces of fire-brick stoves instead of the iron-pipe stoves formerly used. The improvements have consisted in making them much taller, and in providing better facilities for cleaning Rhein and better valves for distributing the gas and air. It is now generally customary to provide a short chimney on top of each stove. instead of one tall chimney for a series of stoves, connected to them by underground flues.
The Stove. built by the Philadelphia Engineering Works, is shown in Figs. 1 and 2.
The arch spanning the combustion chamber and covering the first clown pass has a span of just half the diameter of the stove, under which there is ample play for the guises, giving every opportunity for a utilization of all the checker-work of the down pass. On top of this short-span arch are built the flues to convey the gases from the top of the chimney pass to the chimney and the bottom brickwork of the chimney proper. To reach the chimney the gases pass down to the bottom and up the chimney pass. The gases from the com bustion chamber enter the down pass, and having passed through it, enter through large arches into the chamber beneath the two symmetrical passes, forming a chimney pass, and rising through them, give off their remaining heat to the checker work, and are received on top into chambers above the checker-work. From each of these segmental passes there are two flues or passages. making four in all, leading to the base of the chimney. The checker-work in all cases has 4I-in. walls and 9-in. openings, which are either square or circular.
1lJitssIcX• tt Crooke's Store is shown in Figs. 8 and 4. This is an English form of stove recently introthiced in the United States by McClure & Amster, of Pittsburgh. The shell. is the ordinary wrought-iron cylinder, with a conical-shaped top. Each stove has its own draft stack. In the center is a large com bustion chamber, into which the gases are admitted at the bot tom, thence passing upward and down through a series of large . segmental-shaped fines, and upward through smaller flues to the escape at the top. The mushroom chimney valve, down when the gases are burning, and up when flue blast is on, works automatically : the pressure of the blast when on closes it, and when the pressure is relieved it opens. being counterbalanced as shown. From the lever a wire is attached,
which reaches to the ground, so that the valve can be held closed to retain the heat during any temporary stoppage of the furnace. A door is provided in the stack, so that ready access can be had to this valve, either for cleaning or replacement, if this should become nec essary. When the valve is closed by the incoming blast, the volume of air impinges upon the under side, breaking its force before reaching the brickwork, thus preventing the cutting of the brick. as takes place in some stoves of other types. Both this and the cold-blast valve are readily regulated from the ground. One advantage in this stove, especially in localities where there is a scant supply of water, is that it has but one water valve—the hot-blast valve. This valve is of solid cast-iron. Water is only used in the stein and seat ring. The valve and stem being two separate pieces connected together by a pin or bolt fitting loosely in the holes, finds its bearing on the scat, should the seat in any way be out of level. On the stove, on the outside of these flues, there is an ingenious arrangement of flyback relief doors, which, suddenly opened, when the blast is on, causes a rapid movement of the air in the direction of the opening. For cleaning, caps are taken off from the 24-in, pipes on top, through which pipes a chain is dropped, connecting at the bottom with an open steel scraper fitting the opening. This is drawn to the top by the portable crane shown, and back again, freeing the walls of all adhering dust. The strong points in these stoves are moderate first cost ; minimum of water valves, always a source of trouble and cost ; thick ness of walls, storing up the heat ; the proper burning of the gases throughout the stove ; ease in making repairs to brickwork. The first stoves built in this country were put up for Messrs. Shoenberger, Speer & Pittsburgh, Pa. They were three in number, 10 ft. 0 in. in diameter and 57 ft. high to the eaves; the furnace was 14 ft. bosh and ft. high, at that time making 450 to 500 tons per week with pipe stoves. The difference found on blowing in the improved plant was at once apparent ; the output rose to 800 tons per week, and the fuel consumption diminished to 1,900 and 2,000 lbs. per ton of iron, instead of from 2,700 to 8,000 lbs. See FURNACES, BLAST.
Straightening Machine: see Rolls, Bending.