Comprehensive investigation of process characteristics for oxy-steam combustion power plants

• Oxy-steam combustion exhibits better performance than oxy-CO2 combustion.
• Cost of electricity in oxy-steam combustion is 6.62% less than oxy-CO2 combustion.
• The increase of oxygen concentration in oxidant can improve its system performance.
• The decrease of excess oxygen coefficient can be helpful for its system performance.
• Integration with solar technology can enhance its thermodynamic performance.

Oxy-steam combustion, as an alternative option of oxy-fuel combustion technology, is considered as a promising CO2 capture technology for restraining CO2 emissions from power plants. To attain its comprehensive process characteristics, process simulation, thermodynamic assessment, and sensitivity analysis for oxy-steam combustion pulverized-coal-fired power plants are investigated whilst its corresponding CO2/O2 recycled combustion (oxy-CO2 combustion) power plant is served as the base case for comparison. Techno-economic evaluation and integration with solar parabolic trough collectors are also discussed to justify its economic feasibility and improve its thermodynamic performance further, respectively. It is found that oxy-steam combustion exhibits better performance than oxy-CO2 combustion on both thermodynamic and economic aspects, in which the cost of electricity decreases about 6.62% whilst the net efficiency and exergy efficiency increase about 0.90 and 1.01 percentage points, respectively. The increment of oxygen concentration in oxidant (20–45 mol.%) and decrease of excess oxygen coefficient (1.01–1.09) in a certain range are favorable for improving oxy-steam combustion system performance. Moreover, its thermodynamic performance can be improved when considering solar parabolic trough collectors for heating recycled water, even though its cost of electricity increases about 2 $/(MW h).