1、外文资料 OUR TRIBUNE WHAT IS THE BEST DESIGN FOR A GLASS FURNACE N. Ya. Suvorov (Kurlov Glass works) During 195354 there was a discussion in Glass and Ceramics on the design of tank furnace. The discussion was very informative for workers in the glass industry, for it acquainted them with the existing v
2、iews on this matter, although it was not completed by the presentation of conclusions relating to the courses to be followed in the design of glass furnaces. It must be acknowledged that science has not yet succeeded in making a complete study and systematization of experience gained in the operatio
3、n of glass furnace and has not yet been able to tell us how to design furnaces that will correspond to the present level of knowledge and technology. What is the fundamental principle which ,in our opinion ,must form the basis of the design of perfect tank furnaces ,It will be obvious that by a perf
4、ect tank furnace we mean one that is as efficient as possible in technical and economic respects . The design of a tank furnace must be such that the melted glass passed to the machines in strict sequence .For example, if the capacity of the furnaces is 1000 tons of glass and the machines only after
5、 ten days. We consider that the time has come when it should be possible to arrive at a well grounded conclusion concerning the distribution of currents of glass in tank furnaces and to design a furnace accordingly, so that our basic principle of the strict sequence of the melted glass to the machin
6、es can be realized. It is essential to eliminate undesirable currents of glass and the formation of layers differing in composition, i.e.to keep the kinetics of glass within limits set by the special design of the tank furnace, by the heating schedule adopted, and possibly by the mechanical action e
7、xerted ion the melted glass .Our proposed design for such a furnace is represented in figures 1-6. We do not consider that the problem of constructing a glass tank furnace of our design is more difficult than many others problems already solved by science and technology. The solution of this problem
8、 is within the power of our planning and erection organizations. In the light of the requirements that we have made with respect to the design of glass furnaces, the tanks of the very large tank furnace now in use in the glass industry give the impression of large frying pans in which ,at the glass
9、surface , the glass is not melted but roasted ,and in the roasted condition ,after being cooled for 10-12 hours, is passed to the machines. When such apparently well-melted glass is examined optically, it is found that there are innumerable defects: streaks, whirls, stripes, threads, etc. ,which dif
10、fer from the surrounding mass .Such a glass is non-uniform in mechanical and technical properties ；the productivity of the machines is not as high as it might be and the glass is of lower utility. In the manufacture of optical glass these defects are eliminated by prolonged stirring of the glass wit
11、h special stirrers. In the manufacture of sheet glass, pressed ware, etc., no effort is made to overcome these defects, and all is left in the care of the laws of thermal movement in the glass mass .Rapid cooling of glass, particularly when there in a negative pressure over the glass surface in the
12、cooling zone not to speak of the use of coolers and blowers results in the formation of layers differing in viscosity and therefore in the production of glass full of whirls and waves ,varying in thickness ,badly annealed ,not thermally durable ,giving much breakage during processing ,and not durabl
13、e in use. Slow cooling gives glass that is more stable against leaching .Rapidly cooled glass has different physicochemical properties than the same glass cooled slowly, We cannot agree with the assertion that glass ,having attained to a definite degree of clarity during melting ,cannot be submitted
14、 to a temperature higher than that previously attained, nor with the recommendation that cooling should be rapid and so fix the state of the glass with all its established and non-established equilibria .Also, we cannot accept the advice that we should always adjust the atmospheric regime of the fur
15、nace to the course of the melting process .Such advice is theoretical and cannot serve as a guiding principle for production personal. Prevention of the overheating of the glass by increase in the dimensions of the furnace or with the aid of coolers and ventilators must be regarded as highly erroneo
16、us. The main and greatest defect of large tank furnace and of all furnaces in general, particularly those without barriers (floating bridges, bridge walls etc.) is that the upper layer of glass moves very rapidly to the working end .This has many undesirable consequence, particularly in the non-barr
17、ier method of forming sheet glass by vertical drawing machines. We maintain that glass of the upper, working layer, moving over the intermediate layer disposed between it and the oppositely moving lower layer, particularly entraines glass form the intermediate layer. In its turn, glass of the upper
18、layer partially falls into the intermediate layer. These processes bring about the physicochemical and thermal non-uniformity of the glass the cause of all of the defects indicated above. We consider that in existing tank furnaces-particularly in very large furnace-at least 90% of the glass entering
19、 he machines has been carried there within 12-16 hours after melting by the main working upper layer of the glass mass, which is formed at the hottest mass point of this view can be readily confirmed by coloring the glass mass. From our knowledge of the formation of currents in melted glass in tank furnaces we concluded that it is necessary to learn how to control these currents, to eliminate their harmful effect, and to cause them to assist the process by mixing the layers of glass together and bringing about their homogenization.
