Numerical Simulation Of Atomization Characteristics And Blockage Analysis Of Internal Mixing Nozzle In CC Secondary Cooling Zone

In this paper, the atomization and spraying process of a gas-water internal mixingnozzle in the secondary cooling zone of the continuous casting production line of asteel plant has been studied through numerical simulation. The internal part of nozzleand the spraying space3D models have been built. A breakage model and nozzleatomization model have been used to study the entire atomization process. Theinfluence of inlet air/water pressure on parameters as impact velocity, water flowdensity, droplet size, cooling intensity has been analyzed. The atomization effect ofthe nozzle is verified.The liquid form at the nozzle spout is mainly composed of jet core droplet orliquid film. With the increase of air inlet pressure, the droplet size decreases. Thediameter of droplet atomized by jet core is98.1-1258.6μm, while the one atomized byliquid film is28.2-1649.1μm. The suitable liquid forms of all working conditions havebeen chosen and a program has been written to calculate the secondary atomizationprocess in the spraying space and the diameter of droplet is30.9-1038.8μm. Themaximum penetration depth of a droplet through the steam layer on the slab surfacedecreases as the inlet air pressure increases, and it increases as the inlet water pressuredecreases. According to the minimum droplet impact velocity of all conditions, adroplet diameter to penetrate the steam layer is567.2μm. With the increase of inletpressure, the velocity of nozzle spout ranges from40m/s to180m/s and the impactvelocity ranges from11m/s to27m/s. Compute face method has been used to acquirethe simulated water flow density of all conditions which ranges from0.006L/(m2·s)-0.03L/(m2·s). The increases of water inlet pressure can greatly increasethe water flow density. The relative cooling intensity differs among all conditions,which decreases as the air inlet pressure increases when the water inlet pressure isconstant. And it does the opposite as the water inlet pressure increases when the airinlet pressure is constant.The LSI of secondary cooling water is0.15-0.19, which slightly causes to limescale and internal blockage of some nozzles. Through the typical condition(condition2) simulation it shows that the1/2main water pipe blockage and the jetcore hole blockage cause uneven distribution of liquid and and asymmetric speed atthe nozzle spout. Compared to the no blockage condition, the blockage conditionshave a peak velocity which is30-70m/s larger and a valley velocity which is5-15m/slarger.