Innovative low-grade waste heat-based design of energy self-sufficient carbon-capture cogeneration system in coal-fired power plants

Abstract

To reduce the cost of carbon capture and utilize the waste heat of flue gas in coal-fired power plants, this paper proposes an innovative low-grade waste heat-based design of an energy self-sufficient carbon capture system. The system is divided into energy demand and supply sides. On the supply side, the waste heat of flue gas is utilized as an energy source to produce the power, cooling, and heat required for the carbon capture process. For the demand side, a monoethanolamine-based carbon capture process is simulated to acquire the energy demand-related information. Finally, by coupling the supply and demand sides, the carbon capture capacity for which the energy demands can be satisfied by waste heat recovery is calculated. The maximum carbon capture capacity is determined to be 27,2977 t/yr when the stripper pressure is 50 kPa and the split-flow ratio of the two flue gas branches is 0.35:0.65. In addition, 14,649 t/yr of H2SO4 can be recovered from the flue gas. Finally, an economic analysis reveals that the system’s initial investment can be recovered in 4.65 years. This design provides a partial-scale carbon capture solution that does not rely on external energy input.