초록 ▼

A multistage process for drying coal in which coal is passed into a first fluidized bed reactor at a temperature of 300 to 550 degrees Fahrenheit, air is fed into the first reactor in order to maintain the density of the fluidized bed at from 20 to 50 pounds per cubic foot, and from about 40 to abou

A multistage process for drying coal in which coal is passed into a first fluidized bed reactor at a temperature of 300 to 550 degrees Fahrenheit, air is fed into the first reactor in order to maintain the density of the fluidized bed at from 20 to 50 pounds per cubic foot, and from about 40 to about 60 percent of the water from the coal is removed from the coal and the first reactor. The partially dried coal is then fed to a second fluidized bed reactor which is maintained at a temperature at least 50 degrees Fahrenheit higher than that present in the first reactor, and substantially all of the water remaining in the coal is removed from the coal.

대표청구항 ▼

We claim: 1. 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

We claim: 1. 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. 2. The process as recited in claim 1, wherein said air fed into said first fluidized bed reactor is at said first temperature of from about 300 to about 350 degrees Fahrenheit. 3. The process as recited in claim 1, wherein said air is fed into said first fluidized bed reactor at a velocity of from about 6 to about 8 feet per second. 4. The process as recited in claim 1, wherein said coal charged to said first fluidized bed reactor is 2"×0" coal. 5. The process as recited in claim 1, wherein said coal charged to said first fluidized bed reactor is selected from the group consisting of lignitic coal, sub-bituminous coal, bituminous coal, and mixtures thereof. 6. The process as recited in claim 1, wherein said coal in said first fluidized bed reactor is maintained at said first temperature of from about 450 to about 500 degrees Fahrenheit. 7. The process as recited in claim 1, wherein said fluidized bed is maintained at a fluidized bed density of from about 20 to about 40 pounds per square inch. 8. The process as recited in claim 1, wherein said fluidized bed is maintained at a fluidized bed density of from about 20 to about 30 pounds per square inch. 9. The process as recited in claim 1, further comprising the step of heating said air prior to the time it is fed into said first fluidized bed reactor. 10. The process as recited in claim 9, wherein said air is heated by a heat exchanger prior to the time it is fed into said first fluidized bed reactor. 11. The process as recited in claim 1, further comprising the step of removing coal particles with a particle size less than about 400 microns from said first fluidized bed reactor. 12. The process as recited in claim 11, wherein said coal particles with a particle size less than about 400 microns that have been removed from said first fluidized bed reactor are fed into a cyclone. 13. The process as recited in claim 1, further comprising the step feeding gas into said second fluidized bed reactor. 14. The process as recited in claim 13, wherein said second temperature in said second fluidized bed reactor is from about 550 to about 600 degrees Fahrenheit.