| The oxygen lance is the essential equipment for modern oxygen steelmaking process whose performance directly affects the steel-making production output, quality, raw material consumption, production work rate and environment and such kind of important targets and so on. The oxygen lance performance quality is decided by characteristic of the oxygen jet flow which sprays from the oxygen lance outlet. Steel-making production efficiency and the energy saving efficiency will be greatly improved if supersonic coherent jet flow technology is applied into converter steel-making. The laboratory jet flow test experiment, water model experiment, thermal state simulation model test and numerical simulation research methods were adopted respectively in this article which comprehensively and systematically gave the oxygen jet flow characteristics of the coherent jet flow oxygen lance and traditional supersonic jet flow oxygen lance as well as the rule of interaction in the steel-making molten bath, aiming at providing theory basis for this technology application. Main research content and result as follows:Physical modeling research on oxygen lance jet flow characteristic. Relatively systematic research on jet flow simulated by the normal temperature air was carried out by using rapid scanning oxygen lance examination system with the microcomputer control hydraulic servo'multi- spots pressure. The main research content includes:weakening rule of single- nozzle jet flow axis speed under different driving pressure; displacement rule of the muti-nozzle jet flow axis compared to nozzle geometry axis; weakening rule of multi- nozzle jet flow axis speed; influence on jet flow impact area due to different operation lance positions; coherent jet flow field velocity distribution rule with the low density helium and so on. The thermal state coherent jet flow physical modeling experiment result indicated that compared to the traditional supersonic jet flow, the coherent jet flow has characteristics such as slowing down its axial weakening and radial direction proliferation, more rigid, more coherent and bigger impact to a molten bath, maintaining the central oxygen jet flow relatively coherent to a certain degree.Numerical simulation research on oxygen lance jet flow characteristic. First the standard k-s double equation model was rectified according to the jet flow physical modeling experiment result. By FLUENT software, several kinds of jet flow were simulated, such as the jet flow in the Laval nozzle under different stagnation pressure, the traditional jet flow without helium accompanying under different stagnation pressure and surrounding temperature,or with the low density helium accompanying flow or under different design parameters and process parameters. The numerical simulation result indicated the supersonic coherent jet flow oxygen lance with low density helium can greatly slow down the weakening of axis speed,increase core area length, make central jet flow maintain its initial velocity and the impact momentum within longer distance apart from the nozzle.Physical modeling research on interaction rule of oxygen lance jet flow and molten bath. Water model experiment was simulated according to Anshan Iron and Steel Company's 180t top-bottom converter process and the experiment similarity number was the revision Freud number with geometry analogue ratio 10:1. The water mold experiment was carried on under the condition of different bottom lance arrangement, different top-bottom blowing current capacity, different blowing lance position. The experiment not only gave the design parameters and the structure parameters for best stirring top-bottom converter, but also showed that the coherent jet flow oxygen lance may achieve the result of top-bottom converter stirring effect. If the coherent jet flow oxygen lance can be applied in the converter, bottom blowing system of converter can be canceled. In that case, not only the converter equipment can be simplified, but also the converter lining life can be improved, as well as the steel-making technology transformation.At present, the coherent jet flow oxygen lance technology only obtains the preliminary application in several electric furnaces like domestic Baoshan Steel Corporation's due to its technology security. This technology application in the overseas converter steel-making is still at the test stage, while blank domestically. So mathematical and physical analogue research on supersonic coherent jet flow oxygen lance characteristics can play certain model and instruction role in researching coherent jet flow oxygen lance and its application in electric furnace and converter, providing important theory value and practical significance for steel-making development of our country.
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