Compression behaviour of pulverized coal under gas pressurization for the gasification process

The discharge of pulverized coal from the lock hopper is one of the important processes for entrained-flow pulverized coal gasification technology. However, improper gas pressurization of the lock hopper may prevent the smooth discharge of pulverized coal due to its compression effects. In this paper, the compression behaviour of pulverized coal under gas pressurization was investigated by a high-pressure visualization tank. It is found that the gas pressurization rate, rather than the tank pressure, is the principal factor affecting the powder compression behaviour. The compression process of pulverized coal is completed within approximately 100 kPa, even if the final tank pressure is as high as 4000 kPa. The particle size also has a significant effect on the compression behaviour: when the Sauter mean diameter is greater than approximately 45 mu m, the compression effect is significantly reduced. The compression mechanism under gas pressurization was discussed, and a correlation model between the relative compressive density and the pressurization rate was established with an error of less than +/- 3%. The experimental results not only deepen the understanding of powder compression caused by gas pressurization but also provide a reference for lock hopper operation in entrained-flow pulverized coal gasification.