Patent Application
20110079017
The subject matter disclosed herein relates to carbon sequestration and more specifically to sequestering carbon in power systems.
Power systems often emit carbon dioxide exhaust gases. Carbon sequestration systems remove the carbon dioxide gas from the exhaust gases and store the carbon dioxide.
The removal of the carbon dioxide gas from the exhaust gases consumes energy that otherwise would be utilized for generation of useful shaft power. A method and system that allows a system to sequester carbon and operate more efficiently is desired.
According to one aspect of the invention, a system for power generation comprises, an engine operative to output an exhaust gas, a carbon capture means operative to remove carbon dioxide (CO2) from the exhaust gas and output the CO2, and a compressor operative to receive the CO2 and output compressed CO2 that cools a component of the engine.
According to another aspect of the invention, a method for operating a power system including outputting exhaust gas from an engine, removing carbon dioxide (CO2) from the exhaust gas, compressing the CO2, and cooling a component of the engine with the compressed CO2.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Carbon capture means and sequestration (CCS) is used to remove CO2 from system exhaust gases and store the CO2 in a sequestration location. CCS methods often consume energy, resulting in a loss of system efficiency; for example, post-combustion amine-based removal of CO2 uses energy for solvent regeneration e.g., thermal energy from a heat recovery steam generator or steam turbine extraction, and power used to drive a compressor that compresses the CO2 for sequestration. Gas turbine engines often use pre-combustion compressed air (bleed air) to cool engine components. The use of the bleed air reduces the performance, i.e., output and thermal efficiency, of the gas turbine engine.
The use of CO2 in a closed loop to cool the HGP components of the gas turbine 102 increases the power output and efficiency of the gas turbine 102. CO2 has better heat transfer properties over compressed air, i.e., higher specific heat, in order to achieve the cooling of the HGP components of the gas turbine 102 with a smaller amount of coolant flow. The use of CO2 as a turbine coolant to replace the bleed air from the compressor allows more compressed air to be used for combustion and turbine expansion for useful shaft power generation. Bleed air from the compressor typically enters the gas flow path and mixes with the hot combustion gases upstream of the first stage rotor inlet, where it starts useful work generation via expansion. The use of CO2 as described above, avoids the undesirable lowering of the turbine inlet temperatures by mixing with bleed air and reduces temperature differences between the turbine inlet and the rotor inlet (firing temperature) of the gas turbine 102. The increased efficiency and power output of the gas turbine 102 when cooled by CO2 offsets a portion of the inefficiencies induced in the system 100 by the CCS process. Thus, the increased gas turbine power output offsets a portion of the total CCS power loss that includes the lost steam turbine power output due to the thermal energy used to capture the CO2 from the exhaust gases, and the parasitic power consumption used to compress the captured CO2 for sequestration.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
