Entrained flow coal gasification is the key technology in IGCC field for its cleanness and high-efficiency. High-pressure and dense-phase pneumatic conveying of pulverized coal is of great importance for the entrained flow pulverized coal gasification. There are great differences between dense-phase pneumatic conveying systems at high pressure and common pneumatic conveying systems because of its lower conveying speed, high solid concentration and complex flow patterns.
By changing conveying pressure, total differential pressure and fluidizing gas flow rate, experimental investigations were conducted on the conveying characteristics of pulverized coal with different coal category, different particle size, and different moisture content. The results showed that pneumatic conveying at high pressure is more propitious to obtain higher solid flux, higher solid-gas ratio and lower velocity transport. Solid flux increased with the total differential pressure but the trend was lowered at last due to the system limit. Solid-gas ratio increased at first and then decreased with the total differential pressure. Both solid flux and solid-gas ratio increased slightly with fluidizing gas flow rate at first and then decreased a little for the pulverized coal of two different particle sizes. Pulverized coal with the smaller particle size possessed better conveying ability and was easier to obtain higher solid-gas ratio. Solid flux of Inner Mongolia lignite decreased with the increasing moisture content in the pulverized coal. Conveying ability of Yanzhou bituminous coal was the best and Inner Mongolia bituminous coal was the worst among the three representative coal kinds in China tested. The characteristics of the pressure drops at different pipeline test sections were investigated considering the total differential pressure, solid-gas ratio, particle sizes and moisture content, respectively. Supplemental gas flow rate should be restricted to a range in order to transport successfully when conveying Inner Mongolia bituminous coal of 300μm. The work above will provide valuable experiences for future research on high-pressure and dense-phase pneumatic conveying of pulverized coal in IGCC field.
Effect of properties of pulverized coal on dense phase pneumatic conveying at high pressure
