Method for thermally upgrading carbonaceous materials

Abstract

Carbonaceous materials are thermally upgraded in a pressurized steam environment to remove moisture and other byproducts. A variety of water/solid separation devices may be employed in a process vessel to maximize moisture removal from the upgraded charge. Heating media inlet nozzles and process chamber vents are strategically positioned at the process vessel wall to minimize short circuiting of heating media to vessel outlet vents and to continuously separate hot water removed from the charge and condensed steam, such that the upgraded material removed from the process vessel is not discharged with accompanying free moisture. After upgrading, the charge may be rehydrated to improve its stability during shipping and storage.

1 . A method for upgrading energy content of a charge of carbonaceous material having a first equilibrium moisture level comprising:
 directly contacting the charge with a heating medium under pressure to heat the charge to drive moisture from the charge to a second moisture level below the first equilibrium moisture level and to lower an equilibrium moisture level of the charge to a value between the first equilibrium moisture level and the second moisture level; and   separating driven moisture from the charge.   
   
   
       2 . The method of  claim 1  further comprising heating at least a portion of the charge via indirect heat exchange. 
   
   
       3 . The method of  claim 1  further comprising:
 sizing the charge prior to direct contact with the heating medium within preselected upper and lower size limits.   
   
   
       4 . The method of  claim 3  wherein sizes of charge material are distributed within the upper and lower size limits following a Rosin-Rammler index for the charge material. 
   
   
       5 . The method of  claim 1  wherein the carbonaceous material comprises coal. 
   
   
       6 . Carbonaceous material upgraded by the method of  claim 1 . 
   
   
       7 . The method of  claim 1  further comprising venting non-condensable gas while heating the charge so as to maintain uniform temperature conditions throughout the charge. 
   
   
       8 . The method of  claim 7  wherein the venting is performed continuously while heating the charge. 
   
   
       9 . The method of  claim 7  wherein the venting is performed periodically while heating the charge. 
   
   
       10 . The method of  claim 1  further comprising:
 rehydrating the charge to a third moisture level higher than the second moisture level but less than the first equilibrium moisture level of the charge.   
   
   
       11 . The method of  claim 1  wherein the heating medium comprises saturated steam. 
   
   
       12 . The method of  claim 11  wherein the charge is heated to between a minimum temperature where structure of charge particles become elastic and a maximum temperature where pyrolysis occurs. 
   
   
       13 . The method of  claim 12  wherein the minimum temperature is about 400° F. and the maximum temperature is about 500° F. 
   
   
       14 . The method of  claim 13  wherein the charge is heated under pressures of between about 247 psia and about 680 psia. 
   
   
       15 . The method of  claim 1  wherein the heating medium comprises superheated steam. 
   
   
       16 . The method of  claim 11  wherein a portion of the heating medium comprises compressed hot water condensed from the saturated steam. 
   
   
       17 . The method of  claim 15  wherein a portion of the heating medium comprises compressed hot water condensed from the superheated steam. 
   
   
       18 . The method of  claim 1  wherein the charge is directly contacted with the heating medium under pressure for a time period of about 5 minutes to about 1000 minutes. 
   
   
       19 . The method of  claim 1  wherein the charge is directly contacted with the heating medium under pressure for a time period of about 15 minutes to about 60 minutes. 
   
   
       20 . The method of  claim 1  wherein the charge is directly contacted with the heating medium under pressure for a time period of about 20 minutes to about 30 minutes. 
   
   
       21 . The method of  claim 1  wherein the second moisture level is between about 20% and about 60% of the first equilibrium moisture level. 
   
   
       22 . The method of  claim 10  wherein the third moisture level is between about 101% and about 125% of the second moisture level. 
   
   
       23 . The method of  claim 10  wherein the third moisture level is between about 110% and about 120% of the second moisture level. 
   
   
       24 . The method of  claim 10  wherein rehydrating is carried out in a moisturizing chamber. 
   
   
       25 . The method of  claim 10  wherein rehydrating is carried out by spraying the upgraded charge with water via at least one spray nozzle. 
   
   
       26 . The method of  claim 10  wherein rehydrating is carried out by blending an upgraded charge with non-upgraded carbonaceous material. 
   
   
       27 . A method for upgrading energy content of a charge of carbonaceous material having a first equilibrium moisture level comprising:
 directly contacting the charge with a heating medium under pressure to heat the charge to drive moisture from the charge to a second moisture level below the first equilibrium moisture level and to lower an equilibrium moisture level of the charge to a value between the first equilibrium moisture level and the second equilibrium moisture level;   separating driven moisture from the charge; and   adding a reactive gas to the heating medium in an amount sufficient to cause mercury level in the charge to decrease.