Operational Process and Characteristics of Liquid-gas Jet Pumps with the Ejected Vapor-gas Medium

Abstract

In many industrial processes, the use of a liquid-gas jet pump refers to the ejection of the vapor-gas medium, i.e. a medium containing non-condensable and condensable gases in the liquid jet. Conventional calculation methods are used for jet devices that eject non-condensable gases. However, the presence of steam in the medium ejected makes a significant contribution to the operational process and, consequently, its mathematical description and device specifications. The article deals with the development of physical and mathematical models and determination of properties of liquid-gas jet pumps (LGJP) with an ejected vapor-gas medium. While calculating the performance there were used: Bernoulli equation – for spin-up of the active flow in the nozzle device; water balance equation, heat balance, conservation of momentum – for vapor condensation in the suction chamber; momentum equation and isothermal state equation of liquid-gas mixture – for mixture of media in the mixing chamber; liquid-gas mixture flow equation– for transformation of excess kinetic energy into the potential energy in the diffuser. Extremal characteristics that reflected the potential of the LGJP work were calculated on the basis of the equations. Analysis of specifications was carried out in a non-dimensional coordinates – in terms of the ejection coefficient by dry gas and compression ratio. The calculation of set of extremal characteristics with different ratios of the steam flow to the liquid showed that the presence of steam in the pumped medium degrades performance, i.e. the ejection coefficient is reduced at a constant compression ratio.