STEAM DRY FLOORS.
A good method for drying brick is to employ an iron floor, Hued underneath, the exhaust steam from the engine being turned under the floor loose.
In constructing a drying floor of this kind the following are good directions, which may be varied to suit special circum stances : First, lay down a bottom floor of any cheap, suitable material—hard, discolored brick and bats are as good as any thing ; lay this floor with a slight fall to an outlet or drain, so that the condensed steam may be properly conveyed away in stead of being left to soak into the ground, as sometimes is foolishly done. When the floor is laid the joints should all be made tight with liquid lime poured over it and well ground in. About 10 or 12 inches above this the iron plates should be laid. The plates should be as level as possible, in order to make good joints and confine the steam. If of cast-iron they should be not less than one-half inch thick and not more than two feet wide ; the length is limited only by the necessity of being straight and the ability to handle them. If of wrought-iron, they need not be over one-fourth inch thick, and may be two feet three inches or (possibly) two feet six inches wide. The walls to carry the plates should be chequered or perforated throughout so as to favor the free circulation of the steam— all but the top course, which must be solid. In laying down the plates they should be soundly bedded in good Portland cement. If the plates are of wrought-iron, the cross-joints should be laid on iron strips, from wall to wall, about three inches wide and one-fourth inch thick, bedded in cement same as other walls. If the plates are of cast-iron, they may be made with a lip on one end to receive the next plate, thus forming the cross-joint. The manner of taking the exhaust steam to the floor depends a good deal on the width ; if the floor is narrow, say not more than forty feet wide, the pipe may be taken across one side, close to the wall ; the outlet for the steam should be about two inches, one under each row of plates, that is, about two feet or two feet three inches apart. If the floor is wider than forty feet, the pipe should go across the centre of the floor, the outlets of course being doubled—that is, a row on each side of the pipe—so as to throw steam both ways ; as it is always possible that there may be some steam remaining uncondensed, its escape should be provided for by one or more outlets into the open air. With regard to the size of the pipe
conveying the steam from the engine under the floor, do not pinch for room. In a long length of piping there is a certain amount of friction which should be compensated for by in creased space in the pipe, so as not to put any back pressure on the engine. Always give a larger sized pipe than if the engine exhausted in the air ; z. e., if the engine would ordinarily need a five-inch exhaust pipe, give not less than six inches when taking the steam under the floor. In conclusion, I will say that a very little reflection is needed to see wherein consists the superiority of the steam-drying floor over other steam drying systems. In the one the heat is obtained directly and immediately from the contact of the steam with the drying sur face, whereas in all systems where the steam is confined in pipes the heat is obtained second-hand from the air warmed by the radiation from the steam pipes.
The above description is from an address delivered by Mr. A. Crossly, of Ironton, Ohio, at the second annual meeting of the National Brick Manufacturers' Association.
Exhaust steam from the engine can also be used advantag eously by turning the steam into a gridiron system of steam pipes laid under a slat floor ; air being admitted under the pipes, and by passing over them becoming heated, ascending vertically and passing out at the roof of the shed. By distribut ing steam pipes uniformly under the drying floor exhaust fans are not necessary, as the heated air will rise and escape through openings in the roof without any artificial aid.
The quantity of air admitted can be regarded by suitable openings at the air inlets and outlets, and the temperature we think can be regulated in the same way, and also by suitable stop-cocks.
Of course there are minor detals to provide for, such as ex pansion and contraction of the pipe—drip, etc.
Care must be observed also not to have the openings in the roof so arranged as to cause a current of air to form in the centre or near the roof of the chamber and dry the brick which happen to be in the current, and not thoroughly dry those at the bottom, sides, or corners.