Heat integration for cryogenic co2 separation

Abstract

The present invention relates to a flue gas treatment system for removing CO 2 from a flue gas stream wherein the system includes a flue gas compressor, at least one flue gas adsorption drier, a refrigeration system and a stripper column allowing distillation. Also a method for condensation of carbon dioxide (CO 2 ) in a flue gas stream including a step of separation by distillation of the condensed CO 2 is provided by the invention.

1 . A flue gas treatment system for removing CO 2  from a flue gas stream, comprising
 a flue gas compressor,   at least one flue gas adsorption drier,   a refrigeration system for condensation of carbon dioxide (CO 2 ), in a flue gas stream, said system comprising a refrigeration circuit containing a refrigerant, said refrigeration circuit comprising;
 a multistage refrigerant compressor, 
 a refrigerant condenser, 
 a refrigerant chiller, 
 a flue gas chiller, 
 at least one condenser, 
   and   a stripper column allowing distillation;   wherein the flue gas chiller is arranged between the flue gas compressor and the flue gas adsorption drier and the the flue gas adsorption drier and the at least one condenser are arranged in series upstream of the stripper column.   
     
     
         2 . A flue gas treatment system according to  claim 1 , said system comprises a another condenser being arranged in series upstream of the condenser. 
     
     
         3 . A flue gas treatment system according to  claim 1 , said system further comprising
 a heat exchanger configured to cool at least a portion of the condensed refrigerant using the CO 2  depleted flue gas from the second CO 2  condenser.   
     
     
         4 . A flue gas treatment system according to  claim 1 , said system further comprising
 a first heat exchanger configured to cool at least a portion of the condensed refrigerant using the CO2 depleted flue gas from the stripper column,   a second heat exchanger configured to reheat the CO 2  depleted flue gas from the first refrigerant chiller using warm flue gas from the flue gas compressor,   a first flue gas expander configured to expand the reheated compressed CO 2  depleted flue gas from the first heat exchanger,   a third heat exchanger configured to further cool the condensed refrigerant from the first refrigerant chiller using the using the CO 2  depleted flue gas from the flue gas expander,   a fourth heat exchanger configured to reheat the CO 2  depleted flue gas from the second heat exchanger using warm flue gas from the flue gas compressor,   a second flue gas expander configured to expand the reheated compressed CO 2  depleted flue gas from the second heat exchanger, and   optionally, a fifth heat exchanger configured to reheat the CO 2  depleted flue gas from the third exchanger.   
     
     
         5 . A flue gas treatment system according to  claim 1 , said system further comprising
 a first heat exchanger configured to cool at least a portion of the condensed refrigerant using the CO 2  depleted flue gas from the stripper column,   a second heat exchanger configured to reheat the CO 2  depleted flue gas from the first heat exchanger using warm flue gas from the flue gas compressor,   a first flue gas expander configured to expand the reheated compressed CO 2  depleted flue gas from the second heat exchanger,   a third heat exchanger configured to further cool the condensed refrigerant from the first heat exchanger using the using the CO 2  depleted flue gas from the flue gas expander,   a second flue gas expander configured to expand the reheated compressed CO 2  depleted flue gas from the second heat exchanger, and   a fourth heat exchanger configured to reheat the CO 2  depleted flue gas from the third exchanger.   
     
     
         6 . A flue gas treatment system according to  claim 1 , said system further comprising:
 a selective catalytic reduction (SCR) unit for removal of nitrogen oxides (NOx) from the flue gas stream, arranged downstream of the flue gas adsorption drier, with reference to the general flow direction of the flue gas stream.   
     
     
         7 . A method for condensation of carbon dioxide (CO 2 ) in a flue gas stream using a circulating stream of an external refrigerant, said method comprising:
 a) compressing and at least partial condensing of external refrigerant to obtain condensed external refrigerant,   b) condensing of CO 2  in the flue gas stream by refrigeration of the flue gas stream through at least partial evaporation of condensed external refrigerant obtained in step a),   c) separating by distillation of the condensed CO 2  from the flue gas stream, and   d) chilling of the condensed external refrigerant for use in the refrigeration of step b) using the condensed CO 2  separated in step c).   
     
     
         8 . A method according to  claim 7 , wherein said external refrigerant is propane or propylene. 
     
     
         9 . A method according to  claim 7 , wherein said external refrigerant is ammonia.