Experimental researches of a two-level air-jet protection of an open surface of industrial baths of the big sizes

Abstract

The developed two-level air-jet screen of an industrial bath is experimentally investigated. The principle of its operation is the supply of air by a shielding jet at the upper level and the suction of polluted air at the lower level symmetrically from opposite sides. At this stage of experimental research, the velocity fields and the nature of the interaction of inflow jets and suction flares have been studied. When determining the geometric dimensions of the air-jet screen structure, the location of key components and system elements, it is important to know, ensure and not exceed the allowable values of air flow velocity above the surface of the liquid mirror. During the observations of the aerodynamic properties of two-level air-jet screens, questions arose about the need to use flat rotational flows and control the velocity field in their interaction. Minimization of the interaction of inflow jets and flares of suction is the basis of the concept of designing a sсreen of this type. The shielding conditions have been experimentally confirmed due to the stabilization of the velocity field above the bath surface. The corresponding dependencies of change of formation of the protective air screen from the basic parameters as that a ratio of velocity "inflow-removal" and geometrical characteristics of a design are defined. For the developed air-jet screen of galvanic baths experimentally determined conditions of effective shielding are as follows: the ratio of the width of the slot for ejection of air from the working area to the width of the gas-tight wall is 0.75, and the ratio of screening jet velocity to air removal rate is within 0.3-2.45. This achieves a capture efficiency of up to 90 %. The expediency of arranging an ejection slot under the air supply slot to increase the flow rate and range of the jet has been confirmed.