PRESSURIZATION OF COAL
Pressurizing a solid material as coal is a bit of a misnomer. It is in fact the transport of a solid from one environment to another environment with a higher pressure. Feeding coal or any other solid material into a space with a pressure of more than 5-10 bar is not an easy matter. Reimert (1981 and 1986) has presented systematic reviews of systems that are available or under development. It has been identified as an area requiring additional research and development (Holt 2001; Clayton, Stigel, and Wimer 2002). For coal gasification two different approaches have been followed for pressurizing pulverized coal:
• Lock hoppering, or a sluicing system using an inert gas as the continuous phase.
• Pumping as a slurry with a piston pump water as the continuous phase.