One of the most important means of increasing labor productivity, economy, and rational utilization of material and labor resources in modern metallurgy is reducing the time for repair of the worn linings of metallurgical equipment, mechanization and automation of this process, and economy in refractory materials.In recent years it has become obvious that one of the promising methods in this direction is [I] the torch guniting method. The effectiveness of the guniting process is determined to a large degree by the occurrence of the components of its heat-and mass-exchange processes, in particular the heating of the refractory material particles in the jet and heating of the lining.The wide introduction of torch guniting in metallurgy provides a tremendous saving and therefore at present metallurgists of many countries of the World are displaying active interest in it. However, until now the theory of the guniting process has been developed very weakly and in essence has a fragmentary character. The many publications on torch guniting contain essentially a presentation of specific production experience and descriptions of narrowly specific results of experimental production investigations, the basis of which is practical experience and experience in the study, including theoretical, of similar or related phenomena and processes and also intuitive concepts of the rules of torch guniting. Some publications have been devoted to theoretical investigations but as a rule they consider only individual particular problems in a simplified setting.The need for development of the theory of guniting and, in particular, of the theory of the heat-and mass-exchange processes composing the essence and determining the effectiveness of torch guniting has been maturing for a long time. An experimental solution of these problems is difficult because of the difficulty and complexity in the development and use of a large flame stand (with a flame carrying the solid phase) and also the large variety of technological, geometric, and other characteristics of metallurgical equipment causing in turn wide variation in the conditions of repair of points of wear of the lining.In connection with this, in the State Institute for the Design of Nickel Industry Plants and the All-Union Institute for Refractories an attempt has been made to develop a universal physicomathematical model and software for the common system computer for calculation of a combination of complex heat and mass exchange processes which are the basis of torch guniting of metallurgical equipment. Below is given a brief description of the model developed and individual practical significant results obtained during computer experiments with it.The general model consists of three particular physicomathematical models. The first describes the temperature and velocity field of the gaseous and solid (polydisperse) phases of the guniting flame, the second the conditions of heat exchange of the portion of the lining being gunited with the external in relation to it medium, and the thi...

The degree of optimization of the process of guniting of the linings of metallurgical equipment is determined to a great degree by the possibility of regulating and controlling the working characteristics of the guniting stream. In connection with this there is much interest in investigation of the aerodynamics and heat exchange in two-phase streams (jets) with a high concentration of solid polydispersed guniting particles, particularly in a mathematical description of the guniting stream and an investigation of its aerodynamic characteristics.The guniting jet is formed in the following manner. Through the two coaxial channels to the mouth of the torch are supplied oxygen (through the outer orifice) and the guniting mixture by a flow of compressed air (through the inner orifice).In the inner stream the concentration of the addition is very high and the flow rate of the air and the rate of movement of the gas suspension is much less than the flowrate and rate of movement of the oxygen at the mouth of the torch.It is known that at a certain distance from the orifices the streams are mixed to a sufficient degree and in the main portion they may be considered as a single gas stream with a mixture.Therefore in development of the calculation method a free axially symmetric nonisothermal subsonic stream with a polydispersed solid addition was considered. In the general case, the guniting mixture may contain particles of materials differing in size, densities, and thermophysical characteristics.The basis of the proposed method of calculation of the guniting stream was [1-3].One of the methods of an analytical description of two-phase jet flows used at present is the method of integral relationships of the boundary layer with specified universal functions of distribution of the parameters in the transverse sections of the streams.In jet flow the rule of preservation of the longitudinal component of the full impulse Io is fulfilled;where R(x) is the radius of the stream at a distance of x from the orifice in m, p_ is the density of the gaseous phase in kg/m 3, ug is the velocity of the gaseous phase in ~/sec, r is the current value of the radius of the ss in m, S is the number of fractions of the solid particles, n. is the concentration of particles of the i-th fraction in a unit of volume in l i/m ~, u i is the velocity of movement of the particles of the i-th fraction in m/sec, m. is the average weight of a particle of the i-th fraction in kg, m i = (4/3)~6~pi, Pi is th~ density of the particles of the i-th fraction in kg/m ~, 6. is the average diameter of the particles of the i-th fraction in m, and i is the number of theZfraction of the guniting mixture.Here and subsequently, 0, m, and ~ designate the values of the parameters at the nozzle edge, on the axis, and on the outer edge of the stream.For the i-th fraction the rule of the preservation of its mass flow rate Qi,o is preserved: