Power production plant including liquid oxygen storage and method of operation of the power production plant
Presently disclosed is a power production plant that is operable to store and generate power. In a “charge mode” (when electricity price is low), an air separation unit (ASU) cools and liquefies ambient air into liquid oxygen (LOx), which is then stored in a storage vessel. In a “discharge mode” (when electrical price is high), the stored LOx is used by the power production plant to combust a fuel and form a combustion product stream that can be expanded in a turbine to generate power. The power production plant particularly can utilize carbon dioxide as a recycled, circulating or working fluid so that substantially all carbon dioxide produced in the power production can be captured.
1. A method of operating a power plant, the method comprising:
producing power in the power plant by expanding through a turbine a pressurized combustion stream arising from combusting a fuel with oxygen in a combustor in a presence of a pressurized carbon dioxide circulating fluid;
producing, using the power, liquid oxygen (LOx) from ambient air in an air separation unit (ASU) that is configured for independent operation at a full load capacity or a partial load capacity;
delivering the LOx from the ASU to a liquid oxygen storage vessel;
providing the LOx from the liquid oxygen storage vessel in a condition suitable for use as at least a portion of the oxygen in the combustor;
wherein operation of the power plant and the producing of the LOx in the ASU are independently controlled relative to an economic variable so that one or more of an amount of the LOx that is produced in the ASU, an amount of the LOx that is delivered to the liquid oxygen storage vessel, and an amount of the LOx that is provided for use in the combustor is adjusted responsive to a change in a value of the economic variable and
while the power plant is generating the power, determining a price of the power is above a threshold value;
in response to the price of the power being above the threshold, shutting down the ASU or placing the ASU in a standby mode and producing the power using LOx from the liquid oxygen storage vessel.
2. The method of operating a power plant of claim 1 , wherein the ASU has at least one compressor and during part load operations, the compressor of the ASU is controlled to have variable output.
3. The method of operating a power plant of claim 1 , wherein the method further comprises ramping an amount of the power that is produced in the power plant to follow energy demand by maintaining a constant exhaust temperature of the turbine.
4. The method of operating a power plant of claim 1 , further comprising sizing the ASU such that its maximum flow rate is substantially the same as a maximum flow rate of the pressurized combustion stream through the turbine of the power plant.
5. The method of operating a power plant of claim 1 , wherein a storage capacity of the ASU is controlled based on at least the following parameters: an ASU flow rate, a regional energy market, and a cost of fuel that is combusted in the combustor of the power plant.