A " FLUE " OR " HOT-FLOOR " DRYER Brickmakers who want dryers and do not feel able to build those equipped with pallets, cars, tunnels, tracks, etc., can construct a " flue " or " hot-floor " dryer with less outlay for ma terial and labor than for any other form of reliable dryer. The following plan of construction is most durable and economical : The flues should be 15o feet in length between the furnaces and smoke-stacks. Grade the foundation for flues so that it rises 12 inches from the furnaces to the smoke-stacks. At the stack end let the flues open into a cross chamber, which connects them with the smoke-stack ; this chamber should be as high as the top of the flues, and extend downward 12 inches below bottom of flues, and about i6 inches in width ; this allows any soot that is not drawn into the stack to fall from the flue, thus preventing its accumulation in the mouth of the flue. At the furnace end the flues terminate and rest on a wall ; here they receive heat from a distributing chamber, which in turn con nects with the furnace ; this chamber should be 16 inches wide, and about 6 inches higher than the top of the flues, and covered with an arch or large tiles ; the bottom of the flues should be 12 inches higher than the grates in the furnace. These flues should be 5 inches wide, separated by four-inch walls, four courses high, either laid dry or laid in clay mortar, and covered with a brick on flat or on edge. These partition walls can be of salmon brick—the covers or cap-brick should be hard. The brick must be used about 6 feet from the furnaces, and the furnaces and chamber should be lined with fire-brick. These flues must be covered with tempered mud, and as it dries, roll it with a heavy roller, closing up openings caused by shrinkage ; when too hard for the roller, use tamps, and tamp it until it is hard and nearly dry, then grout the floor with thin mud until dry and air-tight, then pave it with hard brick bedded in thin mud. The tempered mud should be put on so that when the floor is finished the whole thickness including cap-brick and pavement should be as follows : At the mouth of the flues next furnaces 12 inches, gradually reduced to 8 inches when half way to stacks, then gradually reduced to 5 or 6 inches at the stack. This floor, if properly constructed, will dry stiff-clay brick hacked close on end once every 48 hours, and will dry soft-mud brick on flat once every 24 hours. The capacity of these floors with stiff brick on end is to brick per square foot, with soft mud brick 2X per square foot. With flues 150 feet long the smoke-stack should be 40 feet high at least. A stack of this
height, with a flue 24 inches square inside, will answer for a dry floor 4o feet wide by 15o feet in length. A dryer of this size will dry 30,000 stiff-mud brick or 15,000 soft-mud brick per day. The roof can be put on with single comb, or a lighter roof with double comb, and a valley in the centre, supported by a row of posts through the centre of the dryer ; these posts and all the others should rest on brick pillars, so that they are at least six inches above the top of the dryer floor ; there is then no danger of fire being communicated to them from the flues. Most dryers of this kind that catch fire, catch from posts being buried in brickwork or in the ground near the flues. The building should be covered with a shingle, tin, or gravel roof. You must have something that is water-proof. A dryer roof that leaks is little better than none, as it damages brick and moistens the floor. The building should have eave-troughs and drains to carry away surface water, to prevent the flues next the side of the building from becoming damp and clogging with soot. When the flues need cleaning, make an opening across the floor into the flues, about every thirty feet, get a heavy telegraph wire of sufficient length, insert one end into a small plug of wood, and push it through the flues from one open ing to another, fasten a bunch of old clothes to the other end of the wire, and drag it through one flue at a time. (After this bundle is drawn through once, it is dubbed " the black cat," which is appropriate.) In this way the flues can be thoroughly cleaned. The smoke-stack should be provided with a damper, so that it can be closed at night when fires are banked to hold heat under the floor. There should be a furnace about 3 feet wide and 5 feet long, with grates 3 feet in length, making 9 square feet of grate surface for each 8 feet width of dryer, that is, a dryer 40 feet wide would require 5 furnaces of the size mentioned. The slack-bin should extend at least 1 2 feet from the furnaces. Coal slack will make all the heat required. When coal costs too much, wood can be used. The furnace may be the same size as for coal, but for wood only a few grates are needed in the middle of the furnace. Such a dryer will dry brick as well as the most costly kinds, but costs more for fuel to run it and for labor to handle the brick, as the brick have to be rehandled, while in the tunnel-dryers they go direct from the machines to the dryers on the drying cars.