Milenina O. Improvement of blast heating technology by the recovery of blast stoves exhausted gas heat

This dissertation is devoted to the problems of increasing efficiency of the tech-nology of blast heating by exclusion of natural gas from blast furnace stoves (BFS) heating process using waste flue gases for preheating combustion components. Complex researches of thermal work parameters of the complex unit BFS BF- 2 from "Zaporizhstal" JSC showed that the project temperature under the dome of BS is 1350 °C and it is reachable without adulteration of natural gas to the blast gas al-most at all work modes. It has been found out that pipes in the air recuperation are destroyed because of low-temperature sulfate corrosion. The dependence of the total combustion gas temperature before the heat utilization system (SHU) on the time for 3 BFSes in unit, has been got experimentally. Research also determined temperature fields of heat carriers and heating surfaces of 2-way countercurrent heat-exchangers, which unlike already existing ones, take into account temperature distribution along the heat transfer surfaces and the designs features of the respective heat exchanger types. Methodological approach to the calculation minimum allowable temperature of blast gases after heat-exchangers of heat utilization system and in the chimney of heat-exchangers unit has received further development. On the basis of mathematical model of gas cooling during their movement in the pipe, the dependence of blast fur-nace gas cooling degree after heat utilization system on their variable charges and temperature has been found. The calculation method of gas humidity according to its initial parameters has been developed. The dependence of blast furnace gas humidity on its initial tempera-ture has also been determined. The correction coefficient to the calorific value of hu-mid blast furnace gas in relation to the amount of condensed moisture in it as a func-tion from the initial temperature of blast furnace gas has been made. The dependence of preheating of combustion components temperature of on the quantity of condensed moisture has been found. A new scheme of SHU where preheating is used has been developed. The dependence of heating surface areas of heat exchangers on the tem-perature and the flow rate of flue gases, which are used in utilization system has been clarified. It has allowed to determine the rational temperature of flue gases and the appropriate heat-exchangers parameters. Key words: blast furnace stoves, heat-exchangers, exclusion of natural gas, pre-heating of combustion components, heat utilization, energy efficiency.