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The operating principle of dust collectors with swirling counterflows (SC) is examined. An efficiency of 80-85% is achieved during tests of an SC vessel under industrial conditions. The velocity fields of the gas flow in different sections are analyzed over the height of the SC vessel. The influence exerted by the taper of the effective zone of the SC vessel on the dust-entrapment efficiency is investigated. Results are presented for comparative hydrodynamic tests of cylindrical and conical SC dust collectors.Reduction in dust emissions to the atmosphere in the production lines of modern industrial factories is achieved by different effective gas-cleaning methods. Dust collectors with swirling counterflows (SC) had come into increasingly widespread use as fine-cleaning vessels by the start of the 1990s. The operating principle of these vessels is based on a hydrodynamic effect -interaction between swirling gaseous counterflows [1-4]. Vekua [3] and Ovcharenko and Petrov [4] have investigated the overall dust-entrapment effectiveness of SC vessels.During the testing of an SC vessel with a diameter D v = 0.6 m ( Fig. 1) as the third stage of dust entrapment for an expanded-pearlite powder, therefore, an efficiency η = 80-85% was achieved at the Stroiperlit Combine (Fig. 1).This high efficiency of the SC vessel makes it competitive with bag filters traditionally used on production lines of the manufacturing in question [4].The hydrodynamic structure of the gas flows in the SC vessels operating under conditions of maximum dust-entrapment efficiency has been investigated by Sazhin et al. [5]. Analysis of the velocity fields of the gas flow in various sections over the height of the SC vessel has indicated that a reduction in the tangential component of the velocity vector of the flow takes place as it moves from top to bottom (in the direction of the turn in flow -discharge). Frolov [2] has established that the tangential component of the velocity vector of the flow exerts a determining influence on the dust-entrapment process in centrifugal vessels; this obviously leads to a reduction in dust-entrapment efficiency. Investigations of the traditional design of SC vessel with axial-vane swirlers (Fig. 2) of primary and secondary gas flows have therefore indicated that when particles of medicinal talc (d m = 8 µm, ρ = 2200 kg/m 3 ) are trapped in a vessel with a diameter D v = 0.3 m, the maximum overall cleaning efficiency η = 98%.To enhance the dust-entrapment efficiency, it is necessary to ensure constancy of the tangential component of the vector v ϕ of the gas flow over the entire height of the vessel, for which a conical design of SC vessel has been proposed [6]; the testing of this vessel as a component part of an experimental plant was conducted to evaluate its efficiency (Fig. 3). The hydrodynamic structure of the gas flow in the vessel was preliminarily analyzed, and the dust-entrapment efficiency evaluated [7].The vessel was tested under similar conditions to permit comparative evaluation of results obtained and...

A procedure for analysis of power consumed for mixing is proposed, the velocity field of flows investigated, and an estimate of the gas-exchange rate given for hollow vessels.Hollow vessels are classed as a new, as yet little understood, type of compact heat-exchange equipment. A typical hollow vessel is a vertical cylindrical container partially filled with liquid, in the central section of which a squirrel-cage mixer with flexible vertical dispersing elements (blades) is located (Fig. 1).When the rotational speed of the mixer is of the order of several hundreds of rpm, the liquid is forced against the periphery, and a cavity is formed in the central section; the mixing elements, which impart rotation to the cylindrical liquid layer slowed by the outer fixed wall of the vessel, move in the vicinity of the surface of this cavity. Similar vessels are used successfully as photo-fermenters for the cultivation of spirulina or chlorella types of microorganisms [1].In the hollow vessel, a nonuniform centrifugal-force field, which depends on the distance to the axis of rotation, and which provides verticality to the wall of the cavity, acts against the spinning flow of the process medium.Since the displacement of the moving device (mixer, rotor, moving wall) cannot be closed as a result of the medium's inertia, however, an additional nonuniform velocity field relative to the rotating reference system, which on interacting with the angular rotational speed of the device, will give rise to the appearance in the latter of an additional nonuniform field -Coriolis force field.As a result, the combined nonuniform force field will acquire a complex structure in this vessel. The most important element of the hollow vessel is a mixer with a discrete number of meridionally arranged flexible cylindrical blades -cross braces. The mixer with a diameter d m is situated on the axis of the cylindrical container, and is spun at a rotational speed n. The level to which the container is filled with liquid initially establishes the operating position of a mixer blade near the surface of the spinning liquid layer on radius d m /2. On the surface of the cavity, the velocity of the liquid is somewhat lower than the linear velocity of the mixer's elements. The rotating liquid layer is slowed by the fixed cylindrical wall of the container such that the tangential-velocity profile of the liquid in the layer is diminished along the radius. At the rotational speed of the mixer that promotes the formation of a Carman eddy trail on flowing past the cylindrical blades, the structure of the rotating liquid layer is a homogeneous region occupied by Carman eddys, or their filial vortex formations (this is in closer agreement with the actual hydrodynamic situation under the given conditions of flow past the cylindrical blades).In this region, dissipative-free transfer of kinetic moment and energy from the mixer to increasingly deeper layers of liquid is carried out with use of the mechanism of eddy (turbulent) diffusion. Only at the wall of the vessel is...