Abstract

The paper considers the problem of improving the efficiency of operation of blast furnace air supply systems, which are equipped with regenerative heat exchangers with fixed refractory nozzle for heating hot blast. The existing methods of improving the performance of air heaters are analyzed. It is shown that further growth of thermal efficiency of regenerative heat exchangers by optimization of operation parameters or replacement of nozzles is impossible without increasing the overall parameters. As a perspective measure the use of heat storage elements with phase transition is proposed, where as a fusible insert compounds with a certain melting point are used, which corresponds to the operating modes of blast furnace air heaters. They have found application for heat storage in solar systems. Due to the "residual" thermal effect, the nozzles accumulate additional heat. This will increase the heat capacity of the heat exchanger and increase the hot blast heating temperature without changing the dimensional parameters. Operating conditions of air supply systems of blast furnaces are characterized by high temperature level, which is 1200–1350 °С, significant flow rates and speeds of hot and cold coolants, their increased pressure. Therefore, there is a question of choosing appropriate heatacumulative elements taking into account their properties and operating parameters of blast furnaces. Operation of such nozzles has revealed a number of problems, the solution of which requires additional research. For this purpose it is necessary to carry out modeling of quasi-stationary heat-exchange processes in the nozzle chamber of regenerative air heaters in order to select chemical compounds or their mixtures, which meet the operating conditions of blast furnace air supply systems, and to determine the optimal combinations of nozzle materials. Application of this technology will make it possible to obtain higher hot blast heating temper- ature, reduce metallurgical coke consumption or increase blast furnace productivity.

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