Study On The Preparation Reactor Of Ultrafine Calcium Carbonate Using Low Carbon Dioxide Concentration Gas And Carbide Slag

As the governance and utilization issues of carbide slag and aluminum industry gas waste which contains low concentration carbon dioxide is concerned, our research group has proposed the preparation process of ultrafine calcium carbonate using carbide slag and low concentration carbon dioxide. Because the carbonation reaction is gas-liquid two-phase reaction, the conventional carbonation reactor is very difficult to use the low concentration carbon dioxide effectively. Therefore our research group designed and produced a Venturi jet reactor innovatively which is used as the carbonization reactor. This paper focuses on the experimental study of the Venturi jet reactor. Based on the Venturi jet reactor. I designed and assembled a continuous production apparatus, conducted experiments mainly focused on the gas-liquid two-phase mixing characteristics of the Venturi jet reactor. Dual conductivity probes were used in experiments to study the bubble distribution characteristics in the reactor. The usage of particle image velocimetry (PIV) system was aimed at researching the flow field distribution in jet reactor. The pH meter is applied in experiments of different parameters to record the pH value every two seconds which is used for the calculation of the carbon dioxide absorption rate. Conclusions are stated as follows:(1) When the gas flow rate rises, at the same position, the sauter diameter of bubbles, the local void fraction and the interfacial concentration increases significantly; when the fluid flow rate rises, at the same position, the sauter diameter of bubbles keep stable. At the same time, local void fraction reduces slightly. And the interfacial concentration is reduced.(2) Under one same liquid flow rate conditions, if the gas flow rate is also small, the two phase flow is very gentle, the gas-liquid two-phase mixing conditions is unsatisfactory. With the gas flow rate increasing, the turbulence of the two-phase flow gradually increases and swirls becomes large and intense which can benefit the two-phase mixture; Under one same gas flow conditions, when the liquid flow increases, the velocity field in the reactor tended to be more and more disorder, an increasing number of large vortex turbulence is occurred in the reactor; under various conditions, with the movement of the fluid, turbulent is gradually reduced and stabilized.(3) Increasing the flow rate of the gas, the effect of the two-phase mixing is enhanced, the volumetric mass transfer coefficient increases, Thus it can accelerate the absorption rate of carbon dioxide; as the temperature increases, the mass transfer coefficient decreased continuously. It shows that the increase of temperature is not conducive to the absorption of carbon dioxide in the process of carbonation; Under low liquid flow conditions, the increasing of the flow rate of the liquid can accelerate mass transfer, but if the liquid flow rate is too high, it will restrain the gas-liquid mass transfer; under low carbon dioxide concentration conditions, when the carbon dioxide content increased, the gas-liquid two-phase mass transfer can be accelerated; through the analysis of experimental data, the equation about volumetric mass transfer coefficient was derived: AK/V= 0.000817w1.57251Q-0.29667Q3.795191T-1.221939(6) The fluid flow rate and the gas flow rate have little influence on the particle size and particle morphology of the product. The product prepared by low concentration carbon dioxide has a relatively uniform particle size distribution. Compared with the product Preparated by high concentration carbon dioxide, the product prepared by low carbon dioxide concentration have a smaller particle size and uniform distribution. The product of ultra-fine calcium carbonate using low concentration of carbon dioxide content many thin slice of calcium carbonate.