A supercritical CO.sub.2 boiler capable of realizing uniform combustion, corrosion resistance and coking resistance, and a boiler system are provided. The supercritical CO.sub.2 boiler includes a main combustion chamber, an upper furnace, a furnace arch and a flue, wherein a cross section of the main combustion chamber is circular or oval, or is of an N-sided shape, where N>4; at least four burner groups are disposed on the main combustion chamber, each group of burner nozzles corresponding to each burner group includes a recirculating air nozzle, a primary air nozzle and a secondary air nozzle; lateral recirculating air nozzles symmetrically distributed are respectively disposed at two sides of the primary air nozzle, the recirculating air nozzle and the lateral recirculating air nozzle are configured to feed recirculating flue gas or a mixed gas of the recirculating flue gas and secondary air into the main combustion chamber.

The present disclosure generally relates in certain embodiments to a combined cycle power plant system comprising an electrochemical compressor. For instance, in one set of embodiments, the electrochemical compressor is may separate oxygen from a flow of air from an air source to provide a pressurized flow of oxygen to a combustor. In some embodiments, the resulting combustion products may only include oxygen and water without any substantial fraction of other combustion products or contaminants which may facilitate the separation of carbon dioxide (CO.sub.2) for subsequent processes including compression and/or storage.

A supercritical CO.sub.2 boiler capable of realizing uniform combustion, corrosion resistance and coking resistance, and a boiler system are provided. The supercritical CO.sub.2 boiler includes a main combustion chamber, an upper furnace, a furnace arch and a flue, wherein a cross section of the main combustion chamber is circular or oval, or is of an N-sided shape, where N>4; at least four burner groups are disposed on the main combustion chamber, each group of burner nozzles corresponding to each burner group includes a recirculating air nozzle, a primary air nozzle and a secondary air nozzle; lateral recirculating air nozzles symmetrically distributed are respectively disposed at two sides of the primary air nozzle, the recirculating air nozzle and the lateral recirculating air nozzle are configured to feed recirculating flue gas or a mixed gas of the recirculating flue gas and secondary air into the main combustion chamber.

The present disclosure generally relates in certain embodiments to a combined cycle power plant system comprising an electrochemical compressor. For instance, in one set of embodiments, the electrochemical compressor is may separate oxygen from a flow of air from an air source to provide a pressurized flow of oxygen to a combustor. In some embodiments, the resulting combustion products may only include oxygen and water without any substantial fraction of other combustion products or contaminants which may facilitate the separation of carbon dioxide (CO.sub.2) for subsequent processes including compression and/or storage.