| This paper brings forward a resolvent, which is to design a new type of a low hood that without water-cooling framework. The new equipment may solve the problems of dilapidation and leak of traditional low hood. Submerged-arc furnace is a kind of primary equipment for ferroalloy smelting, and the hood system is used for taking away the smoke gas. Through the advancement of technology, a low hood is developed. According to the structure, a low hood can be divided into three kinds: which is made all by fire-resistant concrete, or which is made all by steel with water-cooling framework, or the mixed structure of the two above. And the last kind of low hood is mostly used. The structure of a low hood with water-cooling framework is very complex. It has a large amount of welding line. The working condition of a low hood is bad. Dilapidation and leak of water-cooling framework are existed in many low hoods of submerged-arc furnaces in China. A lot of measures were put forward to solve these problems, for instance, ameliorate the channels of cooling water and use soft water, reduce the quantities of welding line, improve the jointing process, and so on. These measures have made definite effect. A kind of low hood without water-cooling framework has been designed to solve the problems of dilapidation and leak radically. The method of design can be described as below. According to the shape of submerged-arc furnace and the distributing of three electrodes, the furnace cover can be jointed by three 120°fan-shape cover. Through the calculation of barycenter and the static analysis, the furnace cover can be supported on brackets steadily. A new system of cooling water channels has been designed to make the clapboards parts of the steady components. Before tamping of the fire-resistant concrete, some of the "T"or "Y"shape firmwares could be jointed on the hotter surface of the cover. Otherwise, the theories of choosing materials and joint process have been put forward to improve the quality of joint. A numerical calculation has been used to calculate the heat transfer that inside the low hood. The temperature of smoke gas inside the low hood is very high, so the radiative heat transfer is the main type of heat transfer. Compared with zone method and heat flux method, imaginary plane method is a better way to calculate the radiative heat transfer. After reasonable predigestion and hypothesis, a model of the low hood was founded and the equations to this model of imaginary plane method had been wrote out. The computational programs had been written and run by QB (QuickBasic) and MATLAB (Matrix Laboratory). The result of heat transfer indicate the following. The temperature of smoke gas and wall that inside the low hood will drop along with the rise of the altitude and the temperature of smoke gas is higher than that of wall. The rise of blackness of wall will be propitious to the heat transfer, but the rise of dirt's thermal resistance will not be. The mainfold of soot and the accretion of soot's granularity will make the K larger than before, that will minish the heat flux. At the same time the exit temperature of cooling water and the thickness of fire-resistant concrete were gotten. The results are important to the design and application of a low hood. The drawings of a low hood at 6300kVA submerged-arc furnace had been finished by using AutoCAD. The drawings can be used to project construction directly. The design of a low hood at submerged-arc furnace has been applied in many corporations and factories. There are no dilapidation and leak of cover reported till now. It has made great benefit to the corporations and factories.
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