Atomization numerical simulation of high solids content bamboo pulping black liquor based on VOF model

Abstract The application of high-temperature passivation and evaporation crystallization for the black liquor in alkali recovery system has realized that the solids content of black liquor is as high as 70 wt%, even 80 wt%, for atomization combustion in the alkali recovery boiler. Therefore, the increase in the solids content of black liquor has become a development trend and goal of various alkali recovery systems. However, it is difficult to atomize at high solids content, and the resulting large droplets reduce the combustion efficiency of the alkali recovery boiler due to the characteristics of non-wood pulping black liquor such as bamboo pulping black liquor. In this study, we study the atomization performance of bamboo pulping black liquor with high solids content through splash plate nozzle under different injection conditions by means of CFD simulation technology. The four atomization indexes are analyzed in detail including mass flow rate, liquid film thickness, atomization cone angle and droplet size. Finally, a reasonable atomization pattern is given to prepare for subsequent combustion. The results show that the mass flow rate and liquid film thickness decrease but the atomization cone angle and droplet size increase with the increase of injection angle. The liquid film thickness is only related to the injection angle, and the atomization cone angle is not the larger the better. With the injection conditions at 35° and under 150–160 kPa pressure, not only a good atomization cone angle but also the targets of a large flow and small droplet size could be into reality, which effectively improves the ability of alkali recovery of black liquor.