玻璃厂毕业设计外文翻译玻璃熔窑的最优设计.docx

1、玻璃厂毕业设计外文翻译玻璃熔窑的最优设计外文资料OUR TRIBUNEWHAT IS THE BEST DESIGN FOR A GLASS FURNACEN. 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

2、 the existing views 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 i

3、n the operation 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 t

4、hat by a perfect 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 machine

5、s only after 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

6、 the machines 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 mechanica

7、l action exerted 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 thi

8、s problem 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 pansin which ,at the

9、 glass 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. ,whic

10、h differ 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

11、 with 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 t

12、he 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 dur

13、able 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 submit

14、ted 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

15、furnace 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 erro

16、neous.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-ba

17、rrier 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 enterin

19、g 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

20、 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. There is no need to say very much about the harmful effects o

21、f the layers of glass disposed below the upper working current in existing glass tank furnaces, particularly those of large dimensions. If the use of furnaces of large dimensions has effected some improvement in the unfavorable effect of the direct feeding of the machines with glass from the tank fu

22、rnace . Our large furnaces do not have high specific outputs, whereas we know from the technical literature that furnace of 1500 output and higher are in existence. In our opinion tank furnaces provided with throats deserve attention. At the technical literature that furnaces for the manufacture of

23、glass of all kinds , apart from special glasses. The results of the experiments that have been carried out on the manufacture of sheet glass in furnaces provided with throats are not conclusive, and it is very unfortunate that, owing to an insufficiency of fuel and batch, such excellent furnaces hav

24、e been tested under such unfavorable condition. We wish to design a glass tank furnace in such a way that the working stream passing to the machines shall not be in the upper layer of the glass, but in the lower layer .Only under these conditions will the physicochemical and thermal homogeneity be a

25、ttained which will confer good working properties of well-annealed sheet glass without thickness variations with a minimum of breakage. When the working current in a glass tank furnace becomes the lower layer , the imperfection in the glass which occur in tank furnaces having an upper working curren

26、t are eliminated . The glass will be renewed throughout the whole tank within a strictly definite period of stagnation-in the tank and in the channel at the working end-which we maintain are the main sourced of stripiness, thickness variation, friable places, and threadlike whirls. This view is conf

27、irmed by results of the production of sheet glass from bridgeless tanks with direct feeding of machines from the tank furnace.As can be seen from the diagrams showing the principle of the design of our proposed glass tank furnace, the bottom of the tank is not horizontal throughout its length and br

28、eadth, so that the depth of the tank varies correspondingly. The bottom slopes towards the throat, the fall in level being 400-800mm. The fall from the side to the center of the bottom is 200-500mm. The bottom of the furnace is therefore in the form of a gutter. The bottom being of this form, the gl

29、ass is bound to move over its sloping surface in the direction of the throat. The glass will move also from the sides of the tank bottom to the center of the tank and, mixing with the central stream and becoming homogeneous, pass into the throat (fig.3).It will be seen from the temperature curve tha

30、t the maximum temperature occurs at the end of the furnace near to the throat. Since the glass moves along the bottom in the direction of the throat and the maximum temperature is at the throat, the upper layer of glass will move from the throat toward the dog house and, acquiring increased density

31、and homogeneity, fall into the bottom layer and move into the throat as a lower working layer. We are convinced that in a tank of this design operating under the given temperature conditions there will be no return current of glass moving along the bottom in the direction of the dog house1.It will b

32、e seen from Fig.4 that the crown of the tank furnace rises from the throat in the direction of the dog house. A crown of this sort is essential in order to establish the necessary temperature distribution in the furnace (Fig.2) and also so that any air-carried swirls of batch will be carried away to

33、 the dog house by the upper currents of hot gases. The ports and crown must be as low as possible over the tank furnace. The ports in the upper part must be unified with the crown of the furnace (Fig.5). The burners must differ in cross section and in the directions of their flames. The arrangement o