A blast furnace is a metallurgical system of shaft type. Its internal working space is bounded by a refrac tory lining, which is intended to protect the furnace's metal structures from high temperatures and to main tain the initial geometric configuration of the working space for a long time. Numerous factors break down the lining: impacts (when the charge is introduced in the furnace); abrasion (as the batch descends in the shaft); wear by the hot metal and slag; and the penetra tion of soot, zinc, and alkalis into the lining seams. The destructive effect is greatest in the lower part of the furnace: the lining of the well and the hearth. There fore, appropriate measures are taken in the design of the refractory lining and the cooling systems in the well and the hearth, so as to minimize the need for major repairs and ensure reliable furnace operation for 15-20 years.Considerable losses of production occur when large capacity blast furnaces are shut down for lining repair, which may take 2-3 months. The factors responsible for wear and measures for its limitation were considered in [1]. The selection of the cooling system and the refractories and the furnace design are of primary importance here. The hot metal fluxes associated with the hearth design and the quality of the coke employed also have some influence on hearth and hence furnace life. The influence of the produc tivity on furnace life was discussed in [1].At present, Russian and non Russian researchers are interested in the analysis of hearth operation and prediction of its wear, so as to prevent penetration of the hot metal through the lining, which would be cat astrophic. The creation of adequate systems for such analysis and prediction calls for complex mathemati cal software, information regarding the latest achieve ments in blast furnace technology, thermal calcula tions, and computer simulation.At present, the lining thickness may be monitored by measuring the flow rate and temperature difference of the water entering and leaving the cooled furnace section and by means of thermosensors in the lower furnace lining. Other methods are based on ultra sound, radioactive isotopes, elastic shock waves, mea surements of the resistance of electrofurnaces, and so on [2-13].The most promising approach is measurement of the lining temperature and corresponding calculation of the remaining lining thickness on the basis of math ematical models.Existing diagnostic methods based on direct and indirect measurements involve solving nonsteady heat conduction problems and the analysis of huge quantities of data-for example, in formulating a set of possible characteristic states of metallurgical sys tems or their components. The agreement between the models and the actual blast furnace processes depends on the stability of the thermal and geometric charac teristics on which the mathematical models of the refractory lining are based. Monitoring the Wear of the Refractory
The mathematical description and the computer program Devil Erosion of calculation the two-dimensional temperature fields in any vertical and horizontal section of the blast furnace hearth are developed. Calculation is carry out the decision of the equations of heat conductivity with use of indications of the big number of sensing transducers of temperature (to 1000), built in the furnaces firebrick lining between the firebrick blocks. The continuous control of the temperature change in each point allows to define the remained thickness the firebrick lining and to warn, in case of need, the furnace personnel about the beginning of the firebrick lining erosion. The continuous control of change of temperature in the firebrick lining is made on the basis of mathematical model. The system of collecting, processing and transfer information from sensing transducers of temperature or thermal streams in a program database Devil Erosion is used. Programs are installed on blast furnaces of Chinese National Republic: Jinan, Jiyuan and Liuzhou Iron and Steel Works.
This paper presents a two-dimensional description of the temperature field in refractory lining of the hearth in the blast furnace. The mathematical model is based on Fourier differential heat conduction equation. Different solutions of this equation are presented and the optimal quantity and location of thermosensors in the hearth is proposed. This paper also presents a methodology to obtain the heat conductivity of refractory materials.
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