Integrated process for CO2 capture and use in thermal power production cycle

A process for reducing the amount of CO2 released into the atmosphere with the exhaust gas stream produced by the combustion of a hydrocarbon fuel in an internal combustion engine (ICE) used to power a vehicle by capturing at least a portion of the CO2 with a sorbent on board the vehicle, recovering the CO2 from the sorbent and compressing the CO2 for temporary storage on board the vehicle, the process characterized by

• a. passing the hot exhaust gas stream from the ICE through a plurality of heat exchangers in a first heat exchange zone to reduce the temperature of the exhaust gas stream to a value in a predetermined temperature range;
• b. contacting the cooled exhaust gas stream in an absorption zone with a liquid CO2 sorbent solution at a temperature within a predetermined temperature range, the solution comprising a liquid solvent in which is dissolved at least one compound that reversibly combines with CO2 to capture at least a portion of the CO2 from the exhaust gas stream to provide a CO2-rich solution;
• c. separating the CO2-rich solution from the remaining exhaust gas stream that is of reduced CO2 content;
• d. discharging the remaining exhaust gas stream of reduced CO2 content into the atmosphere;
• e. pressurizing the CO2-rich solution and passing it into a boiler for passage in a first heat exchange relation with the exhaust gas stream to raise its temperature to desorb the CO2 and provide a concentrated CO2-lean sorbent solution, and to vaporize a portion of the solvent from the sorbent solution to provide a vaporized solvent/CO2 mixture;
• f. separating the CO2-lean sorbent solution from the vaporized solvent/CO2 mixture in a first separation zone;
• g. passing the vaporized solvent/CO2 mixture to a superheating zone where it passes in a second heat exchange relation with the hot exhaust gas stream directly from the ICE to further increase the temperature of the mixture;
• h. passing the superheated solvent/CO2 mixture to a turbine and expanding the mixture to a predetermined pressure value;
• i. passing the hot expanded solvent/CO2 mixture in heat exchange with the pressurized CO2-rich solution of step (e);
• j. passing the solvent/CO2 mixture to a condensing heat exchanger to lower its temperature to condense substantially all of the solvent vapor to the liquid state;
• k. separating the condensed solvent from the CO2 in a second separation zone and mixing all or a portion of the condensed solvent with the sorbent solution upstream of the absorption zone or discharging the solvent from the vehicle;
• l. recovering the substantially pure CO2 from the second separation zone and passing it to a compression zone to compress and densify the CO2 and discharging any remaining water;
• m. recovering the pressurized pure CO2 and passing it to an on-board vessel for storage or for further processing to reduce its volume by changing its physical state;
• n. passing the pressurized CO2-lean solution from the first separation zone in heat exchange relation to increase the temperature of the pressurized CO2-rich solution from the absorption zone;
• o. introducing the pressurized CO2-lean solution into an expansion device to produce mechanical energy;
• p. passing the reduced-pressure concentrated CO2-lean solution from the expansion device to a mixing device through which solvent is added to restore the desired concentration of the sorbent solution;
• q. cooling the CO2-lean solution to the predetermined temperature range prior to passing it into the absorption zone;
• and
• r. pressurizing the CO2-lean sorbent solution upstream of the absorption zone.