| 摘要 |
A method and apparatus are provided for the dehydration of low rank coal, such as lignite. The coal is formed into particles having a size of less than about 4 inches, is subjected to atmospheric steaming, and then preheating with steam at a pressure of about 20-100 psig. The particles are then entrained in liquid and fed to a high pressure feeder at which they are transferred to a high pressure circulation loop, at a pressure of between about 300-1500 psig. The particles and liquid are fed to a liquid/particles separator at the top of a vertical dehydrating vessel, and the particles at the top of the vessel are contacted by saturated steam. Condensed steam and particles flow downwardly in the dehydration vessel, and are subjected to a counter-current wash at the bottom of the vessel. A slurry of liquid and particles discharged from the bottom of the dehydration vessel has the pressure thereof gradually reduced in a second high pressure feeder, and is transferred to a low pressure loop at a pressure of between about 20-100 psig. The liquid and particles are separated, and then the particles are subjected to evaporative cooling.
|
