Peak-Shaving of the Oxy-Fuel Power Plant Coupled with Liquid O_(2)Storage

Integrating a high proportion of intermittent renewable energy provides a solution for the higher peak-shaving capacity of coal-fired power plants.Oxy-fuel combustion is one of the most promising carbon reduction technologies for coal-fired power plants.This study has proposed a novel oxy-fuel power plant that is coupled with both liquid O_(2)storage and cold energy recovery systems in order to adapt to the peak-shaving requirements.The liquid O_(2)storage system uses cheap valley electricity to produce liquid O_(2)for a later use in the peak period to enhance the peak-shaving capacity.Meanwhile,the cold energy recovery system has been introduced to recover the physical latent energy during the phase change of liquid O_(2)to increase the power generation in the peak period.Technical economies of three power plants,i.e.a 330 MW(e)oxy-fuel power plant as reference(Case 1),the same power plant coupled with only liquid O_(2)storage system(Case 2),and the same power plant coupled with both liquid O_(2)storage and cold energy recovery systems(Case 3),have been analyzed and compared.Thermodynamic performance analysis indicates that the peaking capacity of Case 3 can reach the range of 106.03 to 294.22 MW(e),and the maximum peak-shaving coefficient can be as high as 2.77.Exergy analysis demonstrates that the gross exergy efficiency of Cases 2 and 3 reaches 32.18%and 33.57%,respectively,in the peak period,which are significantly higher than that of 26.70%in Case 1.Economic analysis shows that through selling the liquid O_(2)and liquid CO_(2),combined with carbon trading,the levelized cost of electricity(LCOE)of the three cases have been greatly reduced,with the lowest one of 30.90 USD/MWh shown in Case 3.For a comprehensive consideration,Case 3 can be considered a future reference of oxy-fuel power plant with the best thermodynamic and economic performance.

An Efficient Summer Operation Scheme for a Thermal Power Plant Air Cooling System based on Electric Peak Shaving

We proposed a novel efficient operation scheme for a thermal power plant’s air-cooling system based on peak shaving, in order to cope with high ambient temperature in summer. We introduced an absorptiongeneration equipment with water/lithium working pairs into the air cooled condenser(ACC) to reconstruct the traditional thermal power plant, and established a dynamic thermodynamic model adopting Ebsilon code. We studied the thermodynamic performance variation of the reconstructed thermal power plant throughout a 24-hour cycle and found that the fluctuation ratio of the turbine back pressure decreased to 6% from 78%, which is beneficial for the stable and safe operation of the electric power system. The thermal performance improvement benefited from the exploitation of the heat transfer potential of ACC, which realized via cold duty schedule throughout the day, under different ambient temperature conditions. In this system, the generated power was higher at relatively high ambient temperature than that at relatively low ambient temperature, which solved the electricity demand-supply imbalance problem under high ambient temperature. Finally, the same optimization effects for power thermal plants with an indirect air-cooling system were obtained using the same operation scheme.