Study of the operation and method of calculating the injector for feeding a “Strong” gas-liquid jet

Abstract

An air jet buried in liquid molten cast iron is called a "strong" jet in metallurgy [1]. We used this term in the continuous one-stage method of obtaining melts of alkali metal nitrates or hydroxides from solutions, as proposed in [2, 3]. The internal-mixing air-spray burner [4] used in spraying in combustion of liquid fuel and drying of solutions is used to form a "strong" jet (jet of air with an aqueous solution of a nitrate or hydroxide sprayed in it in the form of drops). In the given case (Fig. 1), the solution is fed in internal channel 2 of the injector with a rate of w w = 0.5-1 m/sec under pressure, and air is fed in outer channel I with a rate of w I = 20-30 m/sec. When these streams enter mixing chamber 3, the solution is broken up into drops due to the large difference in their velocities and a gas-liquid mixture is formed, which flows out into the superheated melt of alkali metal nitrate (or hydroxide) at rate w m from the bottom up. The temperature of the melt is kept constant by heat from an electric heater. The parameters of the technological stability of the process were established in the experiments in [3] with sodium nitrate melt at a constant temperature of 623 K and feed of an air-water jet with a temperature of 298 K: superheating temperature of 50~ specific consumption of air for spraying no less than 0.315 kg/kg (concentration of air in the jet was no more than 0.76 kg H20/kg of the mixture). The "technological stability" of the process means the absence of jolts and collisions in the apparatus, i.e., quiet bubbling of the vapor-air mixture through the melt, identified by the absence of pulsations in the flow rates and pressures of the medium in front of the injector, and the temperature on the boundary of the heat and mass exchange zone in the melt [3]; the absence of crystallization of the melt in its bulk, monitored by nonclosure of the output nozzle of the injector. In conducting more than 200 experiments on injectors with an output nozzle with diameter d equal to 1.5, 2.1, 2.55, 3, and 3.5 mm and consumption of the air-water mixture G m from 6 to 20 kg/h for the concentration of water in the mixture gm from 5.6 to 0.9 kg/kg, the following was established. In feeding air alone, pressure pl and corresponding air flow Gg are established in the injector. The flow rate was measured with a glass rotameter and calculated with the equation for adiabatic flow of gases [5] which has the following form for an adiabatic curve index for air equal to 1.4: