Heat-processing tarred refractories has certain special features compared with the firing of ordinary refractories, such as the need to create special atmospheres, the release of the pitch and gaseous matter from the tar in the goods, and the difficulties of making these substances harmless.Tarred refractories are divided into two groups, i.e., fired and unfired. The first includes corundum and magnesia goods for stopperless steel casting, and the second-dolomite and magnesia for converter production.This classification is important in principle in choosing the heating atmosphere. For fired goodsthe concentration of water vapors is not limited in the atmosphere, and oxygen concentrations of up to 2% are permitted; for unfired goods the water vapor and oxygen contents are limited, respectively, to 0.2 and 1.0%.This article deals with the principles and development of a project for a furnace suitable for heating fired tarred refractories, in particular corundum tiles for the gate valves used in steel casting, prefired and then impregnated with coal-tar pitch. The design of this furnace was perfected by the East Institute of Refracteries in a project for a workshop making refractories for the stepperless casting of steel at the Novomoskovsk Refractories Factory.* The demands that are common to any technology and specific in the particular case were considered in developing the kiln design.The overall requirements of the kiln are a large specific output, high quality of product, the necessary level of mechanization and automation, low specific fuel consumption, good gas sealing, mining capital and working costs, and clean air provision.The specific requirements due to the features of the heat processing of fired tarred refractories are: the existence of a special or controllable atmosphere, maximum gas sealing, and the ability to render the tar and gaseous substances harmless.A continuous-action kiln best meets these demands. This type of kiln has certain advantages, including the controllable atmosphere, maximum gas sealing, and the capacity for rendering harmless the tar and gaseous matter from the pitch, which amount, respectively, to 2.3-3.6 and 0.2-0.4% of the weight of the heat-processed refractories.Continuous-action kilns have not been employed in Soviet practice for heating refractories that are first fired and then impregnated with tar. But in an adjacent industry -the manufacture of electrodes -there is a tendency to use tunnel kilns in which the atmospheres can be controlled; it consists of a mixture of combustion products from organic fuel and volatiles from the carbonization of the binder in the carbon products (ware). The composition of the mixture is 20-80% N2, 10-40% H2, 8-29% CO, 2-15% CO2, 2-20% H20 , 1-5% CH 4 and less than 1% other gases. The maximum temperature of the isothermal soaking in the kilns is 800-1000~ [1, 2].The requirements of a kiln for heating gate-valve tiles are best satisfied by a continuous-action kiln of the tunnel-annular type.The main plan of the kiln with illustrations of t...

The construction of a shaft furnace reactor is considered with temperature regimes for the working medium, the dense bed and the lining. Attention is drawn to possible changes in the operating reactor channel cross section and profile. Nonisothermal movement of the dense bed in the reactor is analyzed and its features are noted in relation to the ratios of the dense bed and channel cross sections.The main element of a shaft furnace is its reactor whose operating space is a vertical channel of predominantly circular cross section. The reactor construction consists of a refractory lining and a steel case over whose height there are three heat-engineering zones: A, B, C. The product being treated in the reactor channel moves as a dense bed under the action of gravitation in a counterflow with the working medium [1] that in the reactor is combustion products of hydrocarbon fuel, atmospheric air and mixtures of them. The heat treatment of a product in each zone and in the whole reactor is specified by temperature regimes of the working medium and the dense bed. A diagram of a reactor with the temperature regimes is provided in Fig. 1. The dense bed regime is provided by the regime of the working medium as a result of heat exchange in the counterflow between the working medium and the dense bed. Both temperature regimes, working medium and dense bed, are not steady-state. The reactor lining is specified by its temperature regime that is also determined by the working medium regime. In contrast to the working medium and dense bed regimes, the temperature regime of the lining is steady-state and it has an effect on the cross section of the reactor channel.Levels of temperature regimes for the dense bed and the internal surface of the lining in channel cross sections over the whole height of the reactor have almost the same values. The level of the temperature regime for the dense bed is higher than the average value of the level of the temperature regime for the lining, determining temperature changes of the channel cross section. During reactor operation the cylindrical channel with an initial diameter of cross section D 1 , uniform over its whole height, under the action of a steady lining temperature regime may be converted into an expanding or contracting channel, any cross section of which will have a its own fixed dimension, D 2 or D 3 respectively.The expanding channel will consist in zones A and B of conically expanding parts, and in zone C of a conically contracting part in the dense bed movement direction. The sizes of the cross sections of the expanding parts are greater than

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