Steam Drying Floors.—There are various systems of drying brick with exhaust steam from the engine or steam direct from the boilers, and several fire-brick works have now in use dry floors, in which are laid parallel rows of one-inch iron pipe, over which, in some cases, is laid a floor of cement. In some plants, fresh blast-furnace slag with a small addition of lime is ground in the mill, and when laid over the pipes is run over with a roller ; the latter plan has been found to be more satis factory, as, while making a floor equally as smooth and hard as cement, it is not so liable to crack from the effects of the heat.
One difficulty met with in this system of dry-floor is the expansion and contraction of the iron pipes in consequence of their being at one time hot and another cold. Several methods have been adopted to counteract this. The most suc cessful one is to bury the pipes in loose sand before covering them over with the permanent floor, thus allowing the pipes to draw without breaking the floor.
Manufacturers who have adopted this plan of drying speak in very satisfactory terms of the result.
There is another steam dry-floor much more economical in working and far more satisfactory. It is extensively used in England, a description of which will be of interest : Parallel brick walls four and a half inches thick are built across the dry-floor to receive the metal floor-plates much after the manner of flue walls to receive tiles, except that in order to have a thorough control over the temperature of the floor the steam flues are divided off into sections ; the outside wall of each section is built tight or with close joints, the intermediate flue walls being built open-work or pigeon-holed, the ends of the brick being about two inches apart.
This is in order that one pipe from the main exhaust may be sufficient for each section. In connection with this portion of the work it must be said the brick should be set in cement, as lime would be affected by the steam.
It is also necessary that consideration should be given to allow for the escape of the condensed water ; the under floor of the flues, having been made water-tight by a covering of cement, should have a slight fall towards the point most suitable for the condensed water to escape or be collected in a cistern for return to boiler, which is preferable, as this water is not only pure, but also warm.
These walls are covered with metal floor-plates ; a useful size being 24 inches by 3o inches, and half inch thick, or three-eighths would be sufficient when you can get them cast that thickness without twisting. A light rib on the under side of the plate
running through the center from each of the four corners will meet this difficulty.
Around the sides and ends of each plate is cast a light flange, extending below the under side three-quarters of an inch. This flange will sink into the cement when placed in the work and help to make a steam-tight joint.
Several attempts have been made to adopt this floor in this country, which have proved failures, owing to the lack of knowl edge how to make them steam tight. For successful ones the writer would refer those interested to the Akron Fire-Brick Works, Akron, Ohio, where they can be seen, and as free from leakage as the boiler itself. The flue walls having been built and the tops trued with a string line, the bottoms made water-tight with cement that the water may flow away in place of draining into the ground and damaging the founda tions, then proceed to lay the plates by first placing across the flue-walls rods of one and a half inch iron the distance apart of the length of the After these have been filled with cement to receive the ends of the plates and the walls covered with cement for the sides, then lay down the plates, always being careful that the end3 and sides of the plates fit tightly together. This full description of laying is necessary, because if carefully adopted it will prevent leakage and render practi cable the best dry-floor that can be put down.
The main exhaust steam-pipe should be taken from the top of the water-heater connected with the boiler, and continued overhead through the middle of the dry-floor and across the line of flues, branches from which at the center of each section right and left should connect with the steam-flues.
In each branch is fitted a valve, by means of which each separate section can be made hot or cold or any intermediate state as required. This is one of the advantages which this system possesses ; another is that the steam is turned directly into the flues, and has only the thickness of the plate between the steam and the brick being dried ; the floor, when the valve is fully opened, being too hot to bear the hand upon. It should be stated that in connecting the exhaust pipe to the heater at boiler into which the exhaust is discharged from the engine, a branch pipe should be connected and passed through the roof ; on the top of this pipe attach a sheet-iron lid on hinges, so that in case too many of the valves in the dry-room are closed, the steam will lift the lid and escape, thus prevent ing any back pressure on the engine.