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Equipment Used Afloat. Ashore Improvements in Furnace Bridge Walls Out- lined and Their Uses and Advantages Analyzed URNACES of g boiler are. the chambers where the fuel is burned. For burning coal, a grate con- sisting of individual cast iron bars rest- ing on cross supports is fitted, with the top surface of the bars slightly below the center line of the furnace at the front and sloping down toward the back, so that at the back end the surface is from 4 to 6 inches below the center line. In order to retain the fuel on the grate, it is necessary to have a wall or projection extending above the grate to a sufficient height so that the average thickness of the fire can be kept on the grate without spilling over into the back ends. For this purpose, a wall 9 to 10 inches above the grate is sufficient. The usual practice has been to have an angle bar or plate or: cast- iron testing. in the © cor- rugation of the furnace and project- is particularly important due to the need of a hot fire at this point com- pletely to burn the gases. Attempts were made years ago to substitute for this brick wall, one made up of cast iron. With steady improvement in design, the cast iron wall is now firmly established in good practice and _ is meeting the condition of service suc- cessfully. Important features in the design of what may be called a mechanical bridge wall of cast iron are: 1—An installation which can be quickly and easily made without use of studs or bolts necessitating the piercing in any manner of the furnace shell. 2.—Provision for the passage of air from the inner end of the ash pan through the wall so that proper and complete combustion may take place. 3.—Arrangement such that any part J.. and is shown in Figs. 1, 2 and 3. In principle, it is a sloping vertical grate with individual sections or bars of cast iron. Fig. 1 illustrates the shape of the individual sections. These are gray iron, and clinkers will not readily adhere. The sections are so designed as to leave air spaces be- tween, admitting air from the ash pan. The installation for an ordinary fur- nace is shown in Fig. 3, represent- ing a longitudinal section through the furnace. The view of this section at the back end, Fig. 3, indicates the different parts clearly. Across. the back end of the furnace, a vertical cast iron plate with a narrow flanged top is fitted to a corrugation. This plate is supported by cast iron angle brackets fitting into the corrugations at each side and bolted to the vertical plate near its top edge. With this as the FIG. 1—INSTALLATION OF FURNACE BRIDGE WALL, SHOWING SHAPE OF SECTIONS, AND SIMPLICITY OF FITTING IN PLACE. FIG..2—SAME FURNACE AS IN FIG. 1 BUT WITH INSTALLATION COMPLETE ing above the grate bars in order to serve as backing for a wall built up of fire brick. As the ship goes on her voyage and the fires are sliced from time to time, this brick wall naturally deteriorates, crumbles, and is more or less dam- aged in the course of a short period of time. This means that the fire brick bridge wall has to be rebuilt frequently, practically after each: voy- age of any duration. Furthermore, clinkers become attached to the wall and also fill the spaces between the grate bars at this end, thus reducing the effective grate surface, by deaden- ing the fire on account of lack of air for combustion, which of course or parts, particularly those parts most subject to deterioration in service, may be readily replaced from spares car- ried. without disarranging the remainder of the wall. 4.—First cost including installation, and maintenance costs to be such as to show a marked saving over the use of the fire brick wall. 5.—That the use of a mechanical cast iron bridge wall in fact increases the efficiency of boiler operation. At least two furnace bridge walls are successfully meeting the severe conditions of service. (One type is manufactured by the Wager Furnace Bridge Wall Co., Inc., 108 Academy street, Jersey City, N. 162 ground work, a horizontal cast iron plate is bolted to the horizontal flange at the top of the vertical cross plate, with its ends resting on the cast iron angle brackets at the sides. Then the lower ‘support for the bridge wall sections is bolted through the horizon- -tal cast iron plate and the flange of the vertical support. The upper part for supporting the sections is in turn bolted to the lower part. With the above parts in place, the wall proper is readily installed by merely slipping into place the individu- al sections making up the bridge wall. The two sections on the extreme ends are cast to the shape of the cor- rugation and are consequently special ¢