REGENERATIVE KILNS.
The objects of all late improvements in the regenerative kilns are to thoroughly mix the air and gas burned in such kilns and to effect a better diffusion, regulation, and equaliza tion of the heat obtained from their combustion.
These objects are best effected by constructing in the walls of adjacent kilns duplex hollow spaces or flues, the alternating portions of the opposite sides of which have slits or perfora tions formed therein, so as to enable the heated products of combustion to be passed or discharged from the lowest part of one kiln into the lowest part of the next kiln—that is to say, the kiln which is being heated preparatory to being fired. These flue-spaces are provided with vertical or horizontal dampers, so as to shut off the communication between the kilns, the slits or perforations in the flue-spaces effecting the improved diffusion. In place of forming such flues in the walls of the adjacent kilns, flues may be formed in the brick-work outside the wall, in which case the air descends some distance below the floor of the kiln, where it passes through ports, regulated by dampers, into a still lower flue, from which it escapes through slits or perforations formed in the lower part of the walls into the burner or chamber, or opening, wherein it mixes with the gas. For the purpose of admitting either hot
air into the upper part of the kilns from an adjacent kiln, or for the purpose of admitting cold air to the upper part of a kiln being fired, a similar flue—that is to say, either duplex or single—is provided with dampers and with slits or perforations in its opposite sides in the walls at or near to the upper part of the kilns. Either hot or cold air is admitted through these upper flues and slits or perforations, when the air admitted at the lower part of the kilns with the gas may be either deficient in quantity to produce complete combustion, or when the tem perature of a kiln at its upper part may be either too high or too low. In place of making the flues duplex, with slits or perforations, as before described, they may be made single, with one side—namely, that through which the discharge takes place—constructed with one, two, or more larger open ings in lieu of slits or perforations above or at a level with the bottom of the kiln, and with slits or perforations at the oppo site side.
The regenerative principle just described may also be ap plied to calcining- kilns and other analogous apparatus.