Flexible pyrolysis system and method

Abstract

Examples of a flexible pyrolysis system are provided that include at least one reaction chamber capable of pyrolyzing a combination of coal in a supercritical carbon dioxide (CO2) atmosphere. The system includes a recuperating and condensing circuit that removes dissolved pyrolysis products from the supercritical CO2 atmosphere and then recovers CO2 for reuse in the reaction chamber. The recuperating and condensing circuit includes multiple stages of recuperators and collectors that can be independently controlled in order to selectively fractionate the pyrolysis products. In addition, the pyrolysis reaction may be controlled to alter the pyrolysis products generated.

1 - 12 . (canceled) 
     
     
         13 . A method comprising:
 flowing an inlet stream of carbon dioxide (CO 2 ) in a supercritical state into a reaction chamber containing coal;   removing, after a contact time, supercritical CO 2  containing dissolved pyrolysis products from the reaction chamber as an outlet stream;   directing a first portion of the outlet stream through a first recuperator/collector stage in which the outlet stream is cooled by a return stream of CO 2  en route to the reaction chamber, the first recuperator/collector stage including a recuperator followed by a condensate collector, to obtain a first stage CO 2  effluent stream and a first stage pyrolysis product condensate;   directing at least a portion of the first stage CO 2  effluent stream through a second recuperator/collector stage to obtain a second stage CO 2  effluent stream and a second stage pyrolysis product condensate; and   reconditioning at least some CO 2  from the first stage CO 2  effluent stream or the second stage CO 2  effluent steam by passing the at least some CO 2  as the return stream through the first recuperator/collector stage to obtain the inlet CO 2  stream.   
     
     
         14 . The method of  claim 13  further comprising:
 directing a second portion of the outlet stream through the second recuperator/collector stage. 
 
     
     
         15 . The method of  claim 13  further comprising:
 maintaining the reaction chamber at a pyrolysis temperature and pressure sufficient to maintain the CO 2  in the reaction chamber in a supercritical state, thereby pyrolyzing the coal to obtain a char and supercritical CO 2  containing dissolved pyrolysis products. 
 
     
     
         16 . The method of  claim 13  wherein the inlet CO 2  stream's temperature is from 300-600° C. and pressure is from 7-30 MPa. 
     
     
         17 . The method of  claim 13  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a third recuperator/collector stage to obtain a third stage CO 2  effluent stream and a third stage pyrolysis product condensate; 
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a fourth recuperator/collector stage to obtain a fourth stage CO 2  effluent stream and a fourth stage pyrolysis product condensate; and 
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a fifth recuperator/collector stage to obtain a fifth stage CO 2  effluent stream and a fifth stage pyrolysis product condensate. 
 
     
     
         18 . The method of  claim 17  wherein the first, second, third, fourth and fifth recuperator/collector stages all operate at different temperatures and the method further comprises:
 controlling the different temperatures of the recuperator/collector stages by setting a position of one or more bypass valves. 
 
     
     
         19 - 20 . (canceled) 
     
     
         21 . The method of  claim 14  further comprising:
 maintaining the reaction chamber at a pyrolysis temperature and pressure sufficient to maintain the CO 2  in the reaction chamber in a supercritical state, thereby pyrolyzing the coal to obtain a char and supercritical CO 2  containing dissolved pyrolysis products. 
 
     
     
         22 . The method of  claim 14  wherein the inlet CO 2  stream's temperature is from 300-600° C. and pressure is from 7-30 MPa. 
     
     
         23 . The method of  claim 21  wherein the inlet CO 2  stream's temperature is from 300-600° C. and pressure is from 7-30 MPa. 
     
     
         24 . The method of  claim 13  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a third recuperator/collector stage to obtain a third stage CO 2  effluent stream and a third stage pyrolysis product condensate. 
 
     
     
         25 . The method of  claim 24  wherein the first, second, and third recuperator/collector stages operate at different temperatures. 
     
     
         26 . The method of  claim 25  further comprising:
 controlling the different temperatures of the recuperator/collector stages by setting a position of one or more bypass valves. 
 
     
     
         27 . The method of  claim 24  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a fourth recuperator/collector stage to obtain a fourth stage CO 2  effluent stream and a fourth stage pyrolysis product condensate. 
 
     
     
         28 . The method of  claim 27  wherein the first, second, third, and fourth recuperator/collector stages operate at different temperatures. 
     
     
         29 . The method of  claim 28  further comprising:
 controlling the different temperatures of the recuperator/collector stages by setting a position of one or more bypass valves. 
 
     
     
         30 . The method of  claim 14  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a 
 third recuperator/collector stage to obtain a third stage CO 2  effluent stream and a third stage pyrolysis product condensate. 
 
     
     
         31 . The method of  claim 30  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a fourth recuperator/collector stage to obtain a fourth stage CO 2  effluent stream and a fourth stage pyrolysis product condensate. 
 
     
     
         32 . The method of  claim 21  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a 
 third recuperator/collector stage to obtain a third stage CO 2  effluent stream and a third stage pyrolysis product condensate. 
 
     
     
         33 . The method of  claim 32  further comprising:
 flowing at least a portion of the CO 2  and dissolved pyrolysis product stream through a fourth recuperator/collector stage to obtain a fourth stage CO 2  effluent stream and a fourth stage pyrolysis product condensate.