Study of Functioning of a Vortex Tube with a Two-phase Flow

As a result of consideration of the phenomena occurring in the vortex tubes, it has been established that there are two forms of swirling dust-gas flow. The circumferential velocity profile in the zone of swirler and return flow is close to the quasi-solid type of rotation. In the peripheral zone, it is close to the quasi-potential type. It has been established by simulation that in the zone of quasi-solid rotation and subsequent transition to a quasi-solid flow, aggregation of particles takes place due to an intense collision of the dust particles drifting to the walls of the vortex tube. There is a 5 to 10 times increase in the determining particle size depending on the value of their specific surface area. In the zone of quasi-potential flow, the bulk of the solid dust particles is concentrated near the tube walls in a zone close to the boundary layer and the dust-free gas concentrates in a zone close to the axial flow. Taking into account the effect of uneven distribution of the braking temperature and consequently creation of a positive gradient of gas temperatures from the tube axis to the walls, thermodynamic and kinetic conditions arise for destruction of CO, NOx, SOx gas impurities (in the case of hot gas with a temperature above 673 K). Thus, when preparing a dusty gas stream from a process source before feeding it to the dust collector, the vortex tube creates conditions for complex purification of the gas stream from dust and gas impurities. Also, efficiency of dust removal in the main unit increases to 99.9 %. This will make it possible to lower the industrial negative impact on atmosphere and reduce threat of global consequences for future generations

Justification of the Calculation Methods of the Main Parameters of Vortex Chambers

The object of research is vortex dust collectors – apparatus in which hydrodynamic regimes are realized. Advantages of using vortex apparatus: work with gases of high temperature, high degree of purification; regulation of the process of gas cleaning from dust due to regulating the secondary air flow. Among the disadvantages of vortex dust collectors are: high hydraulic resistance, the need for powerful blowing apparatus, as well as difficult operation and installation. Apparatus for swirling the flow have a different design and, depending on the gas flow rate, pressure and physicochemical properties of the gas flow at the inlet to the cleaning apparatus, this or that hydrodynamic regime is created in it. When designing vortex chambers, the following design parameters must be observed: Ds/D»0.8; Di/Ds»0.5; Dw/D»0.5¸0.8; the inclination angle of the vortex blades at the inlet of the main flow is b»30¸60º; the inclination angle of the secondary flow nozzles is a»30¸45º. When calculating and designing a vortex chamber, it is necessary to fulfill the conditions for the constancy of the tangential velocity of the total flow along the entire length of the working cavity of the apparatus, ensuring the maximum possible efficiency of its functioning.Analysis of the obtained results for justification of the methods for calculating the basic parameters of the vortex chambers indicates the expediency of using such methods for calculating gas cleaning equipment.When implementing the process of cleaning dust-gas flows in vortex apparatus, not only the processes of agglomeration of dust are observed, but also the destruction of gas toxicants.Mathematical dependencies are considered to allow make predictive estimations to select the conditions of the dry dust removal process and to select the design parameters of the vortex chamber. This opens prospects for the introduction of vortex apparatus in order to reduce the industrial negative impact on the environment, namely the atmosphere

Influence of the Inlet Flow Swirler Construction on Hydrodynamics and Efficiency of Work

The object of research is construction of a vortex dust collector. To solve the problem of increasing the efficiency of dust cleaning in a vortex apparatus with revealing the features of the mechanism and the destructive forces of the process, the features of the hydrodynamic regime of rotation of the gas-dust flow in the zone of the swirler and immediately after it are used.The influence of the swirler construction and the location of its installation in the gas duct for feeding the gas-dust flow on the efficiency of the vortex apparatus is studied. It is shown that the aerodynamic processes that determine the nature of the flow rotation and its flow in the flue after the swirler reach the maximum possible angular velocity of the gas flow rotation in the separation chamber for this construction. It is proved that the swirler construction under the appropriate conditions allows a swirling flow leaving the duct to the separation chamber to reach the maximum possible angular velocity of the gas flow rotation for the given construction. The characteristic regimes of the gas-dust flow in the duct are established immediately after the swirler from its construction. It is shown that for a traditional vane swirler with a swirling flow in one direction, the most effective blade inclination angle corresponds to 45°. Its installation must be carried out in the duct from the end outlet to the separation chamber below by 1.4¸1.6 of the swirler diameter. Before the gas-dust flow flows into the separator, the flow is agglomerated with dust particles. At the exit of the gas-dust flow from the end of the flue to the separation space, the maximum value of the angular velocity of the flow in the separator is ensured. It is established that the blade vortex, which provides for the organization of coaxial turbulent flows in the flue, twisted in opposite directions, will allow more efficient agglomeration of dust particles. A basic construction of the vortex dust collector is developed, which makes it possible to increase the cleaning efficiency with a vortex device to 98–99 %

Generalization of the Aerodynamic Characteristics of the Cyclone and Vortex Chambers During Their Functioning

The object of research is cyclone and vortex chambers. Dust collectors in the form of cyclones and vortex chambers are promising for studying the process and improving their designs. One of the most problematic areas is the purification of aerodisperse systems, high hydraulic resistance, complex operation and installation, the need for powerful blowing devices.The methods used to clean aerodisperse systems from dust, fog and harmful impurities, and the required purification efficiency are determined by sanitary and technological requirements. They also depend on the physicochemical properties of the impurities themselves, on the composition and activity of the reagents, and on the design of the devices used for purification. In connection with this, various technologies and methods of purification are used.During the research:− analysis of the state of the theoretical description of the processes of «dry» purification of aerodisperse systems and known structures is performed;− analysis of methods for calculating the degree of gas purification from dust;− it is proved that modern methods of calculation don't take into account some parameters, namely:the characteristic structure of the swirling flow;extinction of the swirling intensity as the flow is removed from the swirler;changes in gas density in the radial direction under the action of centrifugal mass forces;changes in the distribution of dispersed particles in size after passage of the air-dispersed system of swirlers;− it is suggested to consider in the calculations and studies the dust purification device as a complex;− it is proved that the proposed design most fully reflects the features of the process of «dry» purification of the dust and gas flow;− an equation is obtained which allows to estimate the tangential component of the rotation velocity of aerodisperse systems in a cyclone;− it is proved that the tangential component of the rotation velocity of the aerodisperse systems in the vortex apparatus varies depending on the intensity of the vortex and its attenuation.Due to the study of flow dynamics, it is possible to increase the degree of flow purification, to improve the design of the dust purification equipment

Теоретичні основи безлужних олововмісних покриттів по кераміці в системі RO–SnO₂–Al₂O₃–SiO₂

Theoretical calculations in the oxides systems RO–SnO₂–Al₂O₃–SiO₂, where RO–CaO, ZnO and BaO, have been done. Their structure has been established; eutectic and geometer-topological characteristics have been calculated. The process of the conodes adjustment at 1100 K has been revealed.Проведено теоретичні розрахунки в системах оксидів RO–SnO₂–Al₂O₃–SiO₂ , де RO–СаО, ZnO та ВаO, встановлена їх будова, розраховані евтектики та геометро-топологічні характеристики. В залежності від перебудови конод за температури 1100 К виявлено можливості застосування складів композицій в різних технологіях