| 摘要 |
A method wherein the combustion air is preheated in two steps and the raw materials are preheated in one step, and dust-like and/or gaseous constituents of the combustion gases from the tank furnace such as inorganic fluorides, are removed after the raw materials have been prewarmed. The combustion gases from the tank furnace, at a temperature of, for example, 1400 DEG C, first reach a recuperative heat exchanger (5), where their temperature drops to from about 600 to 650 DEG C, while the temperature of the combustion air, which has already been prewarmed to from 130 to 180 DEG C, is increased to about 950 DEG C. By heat exchange with the raw materials in their tank (12), the temperature of the combustion gases from the tank furnace drops to from 300 to 350 DEG C, after which they are fed to a cleaning unit (21), from where they are used to prewarm the combustion air in a regenerative heat exchanger (23). This reduces the temperature of the combustion gases to about 150 DEG C, but the prior removal of aggressive, gaseous impurities means that there is no fear of acid being produced in the heat exchanger (23) or in the chimney (24). Some impurities, such as fluorine compounds, are already filtered out on heat exchange with the raw materials and enter the melting end (1) together with the raw materials. The bonding of the impurities to lime-containing filter particles takes place in the cleaning unit (21), and the filter particles are themselves regenerated by abrasion of surface layers, it likewise being possible for the abraded material to be fed back to the melting end (1) so that substances such as fluorine can be substantially recycled into the melt and the melt temperature can thus be kept low, which in turn reduces the fluorine content in the combustion gases from the tank furnace. The cleaning unit (21) is divided into chambers, which can be selectively sealed off from the combustion gases in order to regenerate the time-containing filter particles. …<IMAGE>… |
