Tank Furnaces Research Articles

Analysis of service of refractories in glass-melting tank furnaces

The fundamental issues of extending the period between repairs for glass-melting tank furnaces are analyzed. Based on data obtained in studying refractory brickwork after the furnace has been stopped for a cold repair and analyzing the specifics of corrosion of refractories in various structural elements, technical solutions are proposed and implemented enabling one to extend the tank furnace campaign to 7–8 years.

Change in transmission coefficient of screen glass melting in a flame tank furnace

Change in transmission coefficient of screen glass melting in a flame tank furnace

4002 流体/温度場/電場連成解析の応用による,ガラス槽窯炉材選定の適正化(F-1 フォーラム「電磁流体解析関連技術」)

Numerical Analyses of Glass Tank Furnace are performed which include direct Joule heating by electricity. Effects of tank refractory and glass on heating distribution, temperature distribution and flow distribution, is investigated. The results indicate that for the case of glass with low electric resistance ZFC refractory, which has superior performance for high temperature corrosion and for glass defects, is suitable. Whereas, the results show the problem of local heating at refractory when ZFC refractory is used for glass with high electric resistance. In case of using ZFCR which has high electric resistance with not less than the same performance as ZFC, the suitable result is found even for the glass with high electric resistance. The Fluid/Temperature/Electricity combined computational analysis makes it possible to select appropriate refractory for various kind of glass composition to be manufactured.

Change in transmission coefficient of screen glass melting in a flame tank furnace

The practical experience of modifying the transmission coefficient of glass for electron monitor screens in an operating tank furnace is considered. Calculation formulas are proposed that can be used to minimize the period of substandard product yield.

The Role of Convection in Glass-Melting Furnaces

The mechanism of formation and the dynamics of glass melt flows in glass-melting tank furnaces are considered. The results of some studies on this subject are analyzed.

Chemistry, physics and time: the computer modelling of glassmaking.

A decade or so ago the remains of an early flat glass furnace were discovered in St Helens. Continuous glass production only became feasible after the Siemens Brothers demonstrated their continuous tank furnace at Dresden in 1870. One manufacturer of flat glass enthusiastically adopted the new technology and secretly explored many variations on this theme during the next fifteen years. Study of the surviving furnace remains using today's computer simulation techniques showed how, in 1887, that technology was adapted to the special demands of window glass making. Heterogeneous chemical reactions at high temperatures are required to convert the mixture of granular raw materials into the homogeneous glass needed for windows. Kinetics (and therefore the economics) of glassmaking is dominated by heat transfer and chemical diffusion as refractory grains are converted to highly viscous molten glass. Removal of gas bubbles in a sufficiently short period of time is vital for profitability, but the glassmaker must achieve this in a reaction vessel which is itself being dissolved by the molten glass. Design and operational studies of today's continuous tank furnaces need to take account of these factors, and good use is made of computer simulation techniques to shed light on the way furnaces behave and how improvements may be made. This paper seeks to show how those same techniques can be used to understand how the early Siemens continuous tank furnaces were designed and operated, and how the Victorian entrepreneurs succeeded in managing the thorny problems of what was, in effect, a vulnerable high temperature continuous chemical reactor.

Reasons for Variations in Glass Melt Diathermancy in an Operating Tank Furnace

Taking into account variations in glass melt diathermancy, nonstandard situations arising in operating a multi-ton tank furnace are considered. It is demonstrated that an increase in the quantity of introduced cullet, as well as a decrease or a temporary suspension in glass production, lowers the glass melt diathermancy.

Development of the Flow-Through Unit in an Annular Cyclone Chamber for Producing Silicate Melts

The drawbacks of the production of sodium disilicate in glass-melting tank furnaces are described, and the expedience of melting soluble glass in an annular cyclone chamber using industrial sulfate waste is demonstrated. A method for the calculation of the flow-through part of the cyclone chamber for a preset output is proposed. The results of the calculations of a cyclone chamber and a whole aggregate with an output of 40 tons/day are provided, including the environmental, technical, and economical parameters of the production of sodium disilicate and liquid glass based it.

Determination of the Heat-Engineering Parameters of a Glass-Melting Tank Furnace in Changing from Oil Fuel to Natural Gas

The distribution of the thermal load between the burners of the glass-melting tank furnace is optimized and the conditions providing for the melting of the batch not further than opposite the second pair of burners are identified. Operating conditions that ensure complete combustion of fuel with an optimum quantity of excess air are determined. Recommendations are issued for the rational implementation of natural gas combustion in this type of furnace.

Control of the thermal conditions of a tank furnace based on produced glass homogeneity

Mathematical models are constructed to describe the dependences of homogeneity, defects, and specific heat consumption on melting conditions. The efficiency of using daily variations in glass homogeneity and density to control the thermal regime of a tank glass-melting furnace is demonstrated.

Archaeological and Scientific Evidence for the Production of Early Islamic Glass in al-Raqqa, Syria

Archaeological excavations of an Islamic industrial complex in northern Syria at al-Raqqa have revealed comprehensive evidence for Abbasid high temperature industries. Amongst the evidence is some for glass production. The evidence included a glass workshop consisting of the remains of three-chambered ‘bee-hive’ furnaces and a centralised flue system, the debris of casting glass into blocks of three different sizes, glass moils of two diameters (the knock-offs from blowing irons) and discarded lumps of frit, a material produced by the initial stage in glass production. In addition, fragments of a second kind of glass furnace, a tank furnace, were found. Scientific analysis of the products and by-products of this glass industry using electron probe microanalysis has produced an unexpectedly wide range of glass chemical compositions. In some instances discrete compositions are correlated to the function of the glass such as its use to make cast blocks and window panes. In others instances, such as when it is used to make glass vessels, the same apparent degree of specialisation in the deliberate selection of particular glass raw materials is not evident. Scientific analysis of frit has shown that the glass used to make the windows for glazing the al-Raqqa palace complexes was made in al-Raqqa.

Heat transfer in the cross-fired glass furnace

A three-dimensional zonal model is proposed for a study of external heat transfer in a sheet-glass tank furnace’s segment corresponding to the second pair of ports with side and bottom fuel admission to the port. It was found that with bottom fuel admission the melt has a higher heat absorption and the arch temperature is reduced.

Electric furnaces with a fluidized bed for implementing environmentally safe heat treatment processes in machine building

Current designs of electric tank furnaces with a fluidized bed that provide environmentally safe heat treatment of steels as tested under the conditions of machine-building plants are considered.

Recent Trends in the Application of Refractories for Glass Tank Furnaces: Part-I: Regenerator Chequer System

The glass tank furnace is one of the main features of the glass industry in the organised sector. Different types of refractories are used in the furnaces, depending upon the glass composition, end-product and the furnace construction design. The application and performance of the right type of refractories not only prolong the compaign life of the furnace but also influence a rapid and homogeneous melting. Selection of refractories for the glass furnace thus becomes of prior importance also from the point of energy conservation and cost effectiveness of the process. In the present paper, the major types of refractories that are being used for the manufacture of glass and glassware utilizing tank furnace with regenerator system have been taken into consideration. The paper is the outcome of an intensive interaction with the glass and refractories manufacturers. Part I deals with the regenerator chequer system.

Recent Trends in the Application of Refractories for Glass Tank Furnaces: Part-II: Melter, Crown, Refiner and Feeder

The application of refractories in glass-tank furnaces in the organized sector varies according to the type of end-product, glass composition and the furnace construction design. In Part I of this paper, use of different types of refractories in regenerator chequer system was discussed. In this concluding section (Part II), the refractories generally used in melter, crown, refiner, forehearth and feeder have been presented.The technology and application of refractories in glass furnace have since been developed and improved with the changing glass manufacturing techniques. While there are different types of refractories used for different types of glass furnaces, emphasis has been given to the types of furnaces employed for container and sheet glasses in the organized sector only.

Use of a mathematical model in predicting the density of glass for controlling a tank furnace

Use of a mathematical model in predicting the density of glass for controlling a tank furnace

Refractories for Glass Making

Glass melting has changed very little in general principles since the earliest times, still being produced in fireclay pots or crucibles—even up to the present day. In Europe, experiments to melt glasses in tank furnaces began about 1700 A.D., but this became an important form of glass manufacture after Siemens introduced the regenerative furnace in 1870. This design was the basis for the development of modern furnaces and there is still a considerable similarity to the original.Until the late 1920s the glass contact refractories used in tank furnaces were based on fireclay or sandstone blocks. About this time important changes began when sillimanite and fusion-cast mullite refractories became available. However, because of the higher cost of fusion-cast refractories the introduction of these materials was delayed and they did not come into general use for lining the glass melting tank until the late 1940s.The high performance of tank furnaces today is related to a number of factors such as improved furnace design and regeneration, but the most significant has been an improved melting rate brought about by the use of higher temperatures. This has only been achievable as a result of the improved quality of fusion-cast and other refractory materials, such as those used in the furnace superstructure and regenerators. Garstang showed that there has been a steady increase in melting temperatures in the container glass industry. In data going back to 1920, there has been an increase from about 1300°C to some 1590°C. Bondarev showed that the increase in production achieved by using higher temperatures reduces the specific consumption of fuel.

25 Years of Experience with Electric Glass Melting in State Glass Research Institute, Hradec Králové

The electric tank furnace with the vertical molybdenum electrodes which became a basis for the development of the contemporary electric furnace of the State Glass Research Institute (SVUS) type is described. The trends of research and methods, which contributed to gradual improving of this furnace type, are shown. In Czechoslovakia about 20 electric tanks of the SVUS type with the output ranging from 0.4 t/day to 8 t/day are in operation at present. The parameters of some melting aggregates are briefly reported. The aggregates are largely used for melting technical and domestic glasses, illuminating glasses, glasses for imitation jewellery etc. Recently the electric melting has been extended to lead glasses with 6–24% PbO melted in aggregates with the janodic operation to molybdenum electrodes. The results of Mo-electrode and refractory corrosion including assumptions for the frequency of the electrode shift and aggregate working life from the standpoint of the soldier block corrosion in melting end are s...

Technologically required time and energy for glass elaboration

As is known, using different kinds of markers it has been shown that a batch portion, introduced in a glass melting tank furnace, leaves it gradually, after times varying between 7 and 130 h, depending on its construction and working conditions. A mean duration may be assessed, having, for different furnaces, values between 25 and 60 h, called retention time ( t rm). On the other hand, the available data concerning the melting time, the refining time and the conditioning time, resulted in a total of about 8 h. This minimum time required to obtain glass of a given quality from a certain batch was named technologically necessary time ( t tn). Obviously this time is much smaller than the retention time. The ratio t rm t tn has, for the majority of continuous glass melting tank furnaces, values greater than 3, for some glass portions even exceeding 10. The processes taking place by glass melting may be grouped in two categories: energy consuming essentially independent of time, related to transformations and reactions in raw materials and, on the other hand, consuming energy in time, in order to obtain the desired glass melt quality. Using a new indicator - hourly specific energy consumption - it becomes possible to estimate the energy consumption for processes from the second group and, in general, for the time the glass stays at high temperatures in a given furnace. It results that for some furnaces, the energy consumed in the additional retention time ( t rm − t tn, when glass flows useless through the furnace, may represent even 50% of the total energy consumption. The presented diagrams allow to visualise the amount of energy consumption for different processes and the possibilities of intervention in order to diminish it.

Using diatomaceous brick for thermal insulation of the roof of a tank furnace

This paper describes the use, installation, and performance of diatomaceous materials comprised of zirconia, quartz sand, orthophosphoric acid, and various refractory clays as thermal insulation material in the roofs of tunnel furnaces. Long-time service tests have indicated that the insulation has the potential for reducing furnace fuel consumption by seven percent and that it withstands the effects of heat longer than most currently used insulating materials.