Patent ID: 7537622

Claim:
A multistage process for drying coal, comprising the steps of: (a) charging coal to a first fluidized bed reactor, charging air to said first fluidized bed reactor at a velocity of from about 5 to about 8 feet per second, subjecting said coal to a first temperature of from about 300 to about 550 degrees Fahrenheit, and removing from about 40 to about 60 weight percent of the water in said coal from said coal, wherein: 1. said coal charged to said first fluidized bed reactor has a moisture content of from about 15 to about 40 percent and a combined oxygen content of from 10 to about 25 percent, 2. said first fluidized bed reactor is comprised of a fluidized bed with a fluidized bed density of from about 20 to about 50 pounds per cubic foot, 3. said air is fed into said first fluidized bed reactor and said first fluidized bed is maintained at a density of from about 20 to about 50 pounds per cubic foot while water is simultaneously removed from said first fluidized bed reactor, and 4. said air fed into said first fluidized bed reactor is at a temperature of from about 250 to about 400 degrees Fahrenheit. whereby a first, partially dried coal is produced; (b) feeding said first, partially dried coal into a second fluidized bed reactor, feeding air into said second fluidized bed reactor at a velocity of from about 8 to about 12.2 feet per second, subjecting said coal to a second temperature of from about 450 to about 650 degrees Fahrenheit, and removing water from said dried coal until no more than about 1 weight percent of water remains in said coal, wherein said second temperature is at least 50 degrees Fahrenheit greater than said first temperature.