PROCESS FOR THERMAL TREATMENT OF INORGANIC AND ORGANIC MATERIALS IN A SERIES OF SMALL SHAFTS, AND THE APPARATUS TO PERFORM DITTO PROCESS

摘要

Vertical tall retorts are commonly used in a variety of metallurgical and chemical processes. Most of these retorts are counter flowing process, gases flowing upwards through a bed of packed solids moving vertically toward a discharging device. During this displacement, an alteration of the conditions of the gas flow may occur due to the breakage and crepitating of the solid particles. In order to avoid this breakage, the tall vertical tower retort is replaced by a set of short reactors into which the various stages of the process occur, the solid bed remaining stationary. Gases flow in between the reactors, and into them, performing the thermal and chemical exchanges of the process. This system is particularly suitable to the carbonates calcination process. In conventional shaft kilns, reactive lime cannot be produced due to the thermal profile of the kiln. Calcination shaft kilns are thermally efficient, and cost less than the reactive lime producer rotary kiln. In order to take advantage of these characteristics of the vertical shaft kiln, we devised the system of a set of short vertical reactors. In this system the stages of preheating, dissociation and cooling, occur simultaneous and independently. The fuel combustion takes place in the early stages of the calcination, when the strongly endothermic reaction hinders any superheating of the coating lime, resulting in the production of a reactive lime. The system is equivalent to placing a vertical shaft kiln horizontally, and dividing it into several shorter reactors, into which the calcination process stages occur independent and simultaneously. The same principle can be applied to the wood carbonization for charcoal manufacture. The stages of wood drying, pyrolysis and charcoal cooling, occur independent and simultaneously into the several retorts constituent of the system. The process utilizes the gases emitted during the pyrolysis as a source of energy, and as a thermal fluid for the transfer of heat to the wood subjected to the carbonization process.