The procedure for calculating and designing melting tanks for glassmaking furnaces used in the manufacture of container glass is examined. It is shown that mathematical modeling of the internal heat and mass transfer makes it possible to increase substantially the quality of the design solutions, whose implementation creates objective prerequisites for attaining a high energy efficiency and productivity for glassmaking furnaces.Efficient use of the heat energy transferred to the tank as a result of the external heat transfer and intended for implementing the technological process is the main requirement for designing melting tanks. The results of mathematical simulation of the external and internal heat and mass transfer [1] show that in high-productivity glassmaking furnaces even with a flat flame of optimal length the maximum temperatures to which the surfaces of the molten glass and masonry are heated are comparable to their limiting values for refractories in the working space and melting tank. Hence it follows that it is practically impossible to increase the specific productivity of a furnace without intensifying internal heat and mass transfer and minimizing the heat losses through the masonry of the tank.Heat transfer from the high-temperature zone of the tank to its less heated parts is largely determined by the tank's hydrodynamics. In addition, because of the technical features of the glassmaking process it is best to redistribute the heat in the furnace loading direction. The external heating conditions limit the possibility of increasing the temperature of the tank's surface in the melting zone of the mix piles. For this reason, intensification of the glass-forming reactions in flame furnaces without additional electric heating becomes possible only if the temperature of the molten glass is increased in this part of the tank by intensifying heat transfer by means of the convection flow of the free-flow cycle.In taking account of production flow, the effect of the temperature gradient at the surface of the molten glass on the organization of the convection field of the melt is limited. Creating the conditions for a clearly defined convection flow of the free-flow cycle with counterclockwise rotation of the molten glass is a very important function of the melting tank. Increasing melt circulation in this loop is of fundamental importance for heat-transfer and the residence time of melt in the tank. Heat exchange on the right-hand side of the melting tank is determined not only by the boundary conditions on free and forced convection but also on the structural components of the tank which impede melt flow. Therefore, the design of the melting tank must take account of the organization of the convection flow of the process cycle. On the technological level, the evaluation of this flow can be based on two basic requirements. They concern the time that the melt resides in this part of the tank and the thermal uniformity of the molten glass extracted for production. Under the conditions being compared both ...
It was shown that developing an energy-efficient design for a bottle glass furnace implies the use of modern design methodology. It is necessary to include mathematical modeling before the technical design stage in the structure of the traditional stages of work on a furnace design. The boundary conditions of modeling must reflect the conjugate character of external and internal heat exchange and the hydrodynamics of the melting tank.The domestic glass container industry is now developing in conditions of a global increase in prices for fuel and energy and raw material resources. Some glass works have entered a period in which technical inefficiency of production unambiguously predetermines economic failure. Thermal energy has been irrationally used in domestic glass melting for decades. The low thermal efficiency of glass-melting furnaces is a problem that must be solved in order to remain in the modern market of manufacturers of glass articles. The situation is now such that the possibility of evolutionary development of the enterprises is actually over. The revolutionary approach related to large expenditures of financial resources primarily involves a change in the mentality of the workers in the industry and design organizations, whose interaction is graphically represented by a conceptual design model ( Fig. 1) It is unconditionally the prerogative of the industrial enterprise to define the goal of the design. The problems that arise during subsequent operation of the furnace are usually related to the rushed and/or unsatisfactory study of this design stage. Continuous use of glass-melting furnaces makes it impossible to update them during periods between servicings. For this reason, in determining the goal of a new design, it is necessary to foresee market trends and the possibility of remaining competitive for the entire lifetime of the furnace.With respect to glass-melting furnaces, defining the purpose of a new design implies solving a Multivariant problem with a large number of variables [2]. Let us separate out the main problem -the heat rate for glass melting and removal of the glass melt from 1 m 2 of glass tank area per furnace campaign. In countries with a developed glass industry, the heat rates for melting bottle glass are on average 5.0 MJ/kg and in the best furnaces, 4.3 MJ/kg. For the second index, the level attained in production is approximately 8000 tons/m 2 . In defining the technical parameters of a design, the budget for constructing the furnace is most important. In this respect, it is pertinent to recall that attempting to minimize costs inevitably results in a compromise whose resolution should not affect the thermal efficiency of the furnace.Let us turn to the problem of the knowledge necessary for developing designs suitable for the world technical level. The complexity of modern glass-melting furnaces does not allow using traditional design methodology based on theoretical knowledge and practical experience in operating lowoutput aggregates with a high heat rate. An up-to-date dat...
The specifics and control algorithms of thermal performance of a glass-melting furnace are described. The methods for setting and monitoring the temperature regulation parameters in the working space are analyzed. The results of calculation of the fuel rate, the maximum roof and glass melt temperatures, and their positions along the furnace depending on its output are given. The advantages of using a mathematical model for the construction of an automated control system for the thermal performance of the glass-melting furnace is demonstrated.The thermal performance of a furnace is understood as a set of heat and mass exchange processes implemented for a prescribed technological process. One of the main conditions of the effective performance of continuous glass-melting furnaces consist in specifying rational regime parameters accepted in glass melting; another condition is ensuring the stability of these parameters. Clearly, to obtain high-quality glass with minimum energy consumption, both conditions have to be satisfied, as they are interrelated and interdependent. The practical implementation of these conditions constitutes the essence of controlling the thermal performance of the furnace.The automation of the mutifactor glass-melting process implies the existence of transfer functions between the main values characterizing the quality of the glass melt and the parameters of the thermal performance of the furnace. In the ideal case we mean the formalization of the "controlled parameters of furnace performance -glass quality" relation. However, the existing methods for estimating the known glass quality parameters are not automated and do not provide a sufficient frequency of measurements to control the glass-melting process. Therefore, in practice the control of the thermal performance depends on certain arbitrary parameters, which to a certain extent determine the quality of glass. These parameters include the value and distribution of temperature in the working space of the furnace, the pressure and composition of the gaseous medium, admissible fluctuations of the glass melt level, etc. The control of these parameters is performed using local automatic systems that are not logically related to each other. Their contemporary evolution is directed to improving control algorithms, increasing the reliability of hardware components of the systems (control sensors, regulators, microprocessors, etc.), expanding the range of information services for the personnel, etc. At the same rime, the methodical basis of control systems has remained unchanged for several decades, although the design of the furnace and its operating intensity have undergone substantial modifications.According to automatic control parameters, including temperature, a glass-melting furnace is a static object [1]. In this context the notion of "controlling the temperature regime of the furnace" understood as temperature variation in time appears incorrect. Therefore, one of the main systems of automated control of the thermal operation of a glass-...
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