SUGAR-CANE SIRUP MANUFACTURE 93 
ash pit. The distribution of heat over the bottom of the pan is 
controlled by filling in the furnace between the end of the grates 
and the chimney. Although all furnaces look very much alike on 
the outside, they differ greatly in the size of fire box, ash pit, chimney, 
and. filling. 
Wieure 6 shows a furnace suitabie for a 12-foot evaporator. The 
dimensions for width, height, distance of grates below pan, and 
thickness of wall apply also to furnaces for evaporators of other 
lengths. For longer furnaces the length of the fire box should be 
increased to 4 or 4144 feet. The chimney of the furnace should be 
as high as the furnace is long. A well-constructed fire box is about 
2% inches longer than the wood used. ‘The highest point in the filling 
of the furnace, where the flames are brought closest to the pan, 
should be approximately 114 feet beyond the middle of the evapo- 
rator toward the sirup end. 
13 
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LLANCT/A FILLING COPED #6777 
LSS CLIENT, BRICK DC Sz 
lL LAL ALLA. LLP 
Fic. 6.—Furnace and 12-foot evaporator 
Some furnace fronts manufactured with grates attached give too 
small a fire box. Moreover, the continual opening and closing of 
the door, in the case of heavy fronts, frequently tears the end brick 
from the furnace. Sirup makers often install a grate in the proper 
position, using for the front a large piece of sheet metal, hung from 
a joist of the pan shed. This inexpensive arrangement works very 
satisiactorily, affording a larger door for firing and rapidity in 
| opening and closing. : 
Beginning at the bottom of the ash pit, a 2-thickness transverse 
| brick wall built up to the bottom of the grates furnishes a support 
for their back end. The wall is then reduced to one thickness of 
| brick and is extended about 6 inches above the grates. This keeps 
the filling of the furnace in place and prevents it from falling back 
into the fire box. The filling is banked up against this wall and 
ecealy slopes up to the highest point, which is about 1% feet 
| beyond the center of the pan. Beyond this point the filling slopes 
| gradually downward to the last compartment of the pan, where it 
| drops off suddenly. If dirt is used for this filling, it should be cov- 
_ ered with a layer of brick cement or hard clay to keep the contour 
. of the filling from being changed by a strong draft. 
