| 摘要 |
26 DEHYDRATION OF LIGNITE OR THE LIKE A method and apparatus are provided for the dehydration of low rank coal, such as lignite, by steam drying or hot water drying. The coal is formed into particles having a size of less than about 4 inches, and is subjected to pre-steaming. 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, and are fed to a liquid/particles separator at the top of a vertical vessel. The particles at the top of the vessel are contacted by saturated steam, or with hot water (e.g. 250-260.degree.C) flowing countercurrently thereto. The particles are ultimately subjected to a countercurrent wash at the bottom of a vessel. A slurry of liquid and particles discharged from the bottom of the vessel after washing has the pressure thereof gradually reduced in a second high pressure feeder, and is transferred to a low pressure loop. The liquid and particles in the low pressure loop are separated, and then the particles are subjected to evaporative cooling to produce dehydrated, dry, low rank coal. |
