Method and system for heating a bed of hydrocarbon- containing rocks

Abstract

Hydrocarbon-containing rocks (e.g, mined oil shale or mined coal or tar sands) are introduced into an excavated enclosure (e.g. a pit or an impoundment) to form. a bed of rocks therein, One or more heaters (e.g. molten salt heaters) are operated to pyrolyze kerogen or bitumen of the rocks. In some embodiments, a hydrocarbon reflux loop is maintained within the enclosure to convectively heat the hydrocarbon-containing rocks by boiling hydrocarbon liquids from a reservoir at the bottom of the enclosure so that vapor passes to the top of the enclosure, condenses, and falls back through the bed. Alternatively or additionally, the rocks may be heated by heaters embedded within wall(s) and/or a floor of the enclosure. Some embodiments relate to techniques for upgrading mined coal to recover both hydrocarbon pyrolysis fluids and upgraded coal (e.g. anthracite coal).

1 . A method of heating hydrocarbon-containing rocks comprising:
 a. introducing the hydrocarbon-containing rocks into an interior region of an excavated enclosure to form a bed of rocks therein;   b. maintaining a reservoir of hydrocarbon liquids substantially at the bottom of the interior region of the excavated enclosure; and   c. heating the hydrocarbon liquids of the reservoir so as to maintain a hydrocarbon reflux loop within the interior region to convectively heat the hydrocarbon-containing rocks.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The method of  claim 1  wherein the interior region is maintained under anoxic conditions during the heating. 
     
     
         5 . The method of  claim 1  wherein kerogen or bitumen of the rocks are pyrolyzed, the hydrocarbon reflux loop supplying at least a portion of the thermal energy required to pyrolyze kerogen or bitumen of the rocks. 
     
     
         6 . The method of  claim 1  wherein the reflux loop vertically spans at least a majority of the rock bed and/or of the interior region of the excavated enclosure. 
     
     
         7 . The method of  claim 1  wherein liquid hydrocarbon vapor of the reflux loop condenses primarily above the rock bed and/or substantially at a top thereof. 
     
     
         8 . The method of claim wherein a majority of the hydrocarbon fluid flow of the reflux loop passes via one or more vertical chimneys that substantially vertically traverse the rock bed. 
     
     
         9 . The method of  claim 8  wherein the vertical chimney passes through an interior of the rock bed. 
     
     
         10 . The method of  claim 8  wherein wall(s) of the vertical chimney are liquid-tight. 
     
     
         11 . The method of  claim 8  wherein wall(s) of the vertical chimney are heat conductors to facilitate conductive heat transfer from (i) hydrocarbon fluids migrating within the vertical chimney to (ii) rocks of the bed. 
     
     
         12 . The method of  claim 1  wherein thermal energy supplied by the reflux loop is sufficient to significantly raise a temperature of at least one location at the top of the rock bed. 
     
     
         13 . The method of  claim 1  wherein the heater(s) are immersed heaters located within a reservoir of hydrocarbon liquid. 
     
     
         14 - 19 . (canceled) 
     
     
         20 . A method of heating hydrocarbon-containing rocks within an excavated enclosure comprising:
 a. arranging the hydrocarbon-containing rocks into rock bed within the enclosure so that one or more substantially vertical conduits substantially vertically traverse the rock bed;   b. respectively maintaining lower and upper hydrocarbon liquid reservoirs at upper and lower elevations, the lower elevation being substantially at the bottom of the enclosure and substantially below the rock bed, the upper elevation being above or substantially at the top of the rock bed,   wherein the upper hydrocarbon liquid reservoir is supplied primarily by boiling of hydrocarbon liquids of the lower reservoir so that vapors formed therefrom substantially vertically traverse the rock bed and condense into liquid of the upper reservoir, wherein at least some thermal energy for the pyrolysis is supplied by convective heat transfer from downward movement of hydrocarbon liquid through the rock bed from the upper reservoir to the lower reservoir.   
     
     
         21 . The method of  claim 20  wherein a floor of the upper reservoir includes a plurality of voids through which hydrocarbon liquids flow downwards into the hydrocarbon bed. 
     
     
         22 . The method of  claim 20  wherein the voids are distributed over the hydrocarbon bed so as to horizontally substantially evenly distribute downward liquid flow from the upper reservoir into the rock bed. 
     
     
         23 - 63 . (canceled) 
     
     
         64 . An coal upgrading method comprising:
 a. introducing pieces of coal into an excavated enclosure to form a rock bed therein, a substantial majority of the coal being bituminous coal having vitrinite reflectance of at most 1.8%;   b. heating the coal of the rock bed so that (i) an average temperature of the rock bed is maintained between 250 degrees Celsius and 400 degrees Celsius for at least one week; and (ii) a majority of the bituminous coal is upgraded into anthracite coal having a vitrinite reflectance of at least 2.5%.   
     
     
         65 . The method of  claim 64  wherein a pressure/temperature history of the coal is regulated so as to maximize a rank of the heated coal. 
     
     
         66 . The method of  claim 64  wherein a high value ultralow volatile anthracite coal is produced.