Influence of different inlet modes on hot carrier gas flow in magnesium nitrate pyrolysis furnace

Abstract

Spray pyrolysis of magnesium nitrate is a way to prepare magnesium oxide solid particles. The gas–solid flow process after the generation of solid particles inside the pyrolysis furnace was studied in this article. Six different inlet modes of hot-carrier gas were designed, and the hot-carrier gas enters the pyrolysis furnace at the same flow rate through the six different inlet modes. The influence of varying inlet methods on the actual running distance of gas flow and the particle sedimentation rate was deeply studied in this article. The longer the distance the hot-carrier gas runs in the pyrolysis furnace, the more conducive it is to full contact with the material. The higher the particle settling rate, the more magnesium oxide particles are collected in the pyrolysis furnace. ANSYS Fluent was used for numerical simulation in this study. The results indicate that when using a tangential inlet, the actual running distance of the hot-carrier gas in the pyrolysis furnace is longer than that of the normal inlet. The actual running distance of the thermal carrier gas at the three tangential inlets is 46.5 m, and that at a single normal inlet is 24.7 m. The former is 88% more than the latter. The sedimentation rate of solid particles at three tangential inlets is 32.24%, and that at a single normal inlet is 12.06%. The former is 167% higher than the latter. The three tangential inlet mode is the best way to increase the actual running distance of the hot-carrier gas and improve the solid particle settling rate in the pyrolysis furnace. The pyrolysis furnace with multiple tangential inlets has two advantages. On the one hand, increasing the running distance of the hot-carrier gas in the furnace is conducive, thereby making the contact between the hot-carrier gas and the material more sufficient. On the other hand, it can increase the capture rate of product particles, improve the product yield, and reduce the dust content of pyrolysis tail gas.