| 摘要 |
This invention relates to a kiln of a compact upright configuration which is constructed so as to successively preheat, heat, and then cool aggregate in a continuous operation while avoiding wasteful loss of heat from the walls of the kiln or in the effluent gases. In the apparatus of this invention there is provided an upright hollow housing having an air inlet opening in a lower portion thereof and an air outlet opening in an upper portion thereof. A fan is communicatively connected to the housing for causing outside air to enter the air inlet opening and flow upwardly through the housing. A fuel burner is provided in the housing for combusting a fuel and thereby heating the air flowing upwardly within the housing. A pair of opposing gas permeable retaining walls of nonlinear zigzag configuration is positioned within the upright housing and extending generally longitudinally thereof in closely spaced relation to one another to define an elongate zigzag passageway of relatively narrow cross section adapted for receiving aggregate at the upper end and for maintaining the aggregate in the form of a relatively thin layer extending generally vertically in a series of oppositely directed downwardly inclined courses of travel.
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