Conceptual design and process assessment of a MSW waste-to-energy plant with oxy-combustion CO₂ capture

Capturing CO₂ from waste to energy plants has attracted increasing interest, particularly for the goal of achieving negative emissions. Oxy-combustion is a competitive alternative technology for CO₂ capture. The main challenge is that oxygen production is expensive. In addition, a subsequent purification process is normally required to removal impurities, such as N2, O₂, and Ar from CO₂. This study presents a conceptual design of an oxy-combustion waste to energy plant with CO₂ capture. A negative emission of 510.6 kg CO₂/ton municipal solid waste has been achieved. The study further assesses the influences of air leakage, oxygen content at the furnace outlet, and purity of O₂ supplied on the energy performance. It is concluded that efforts should be primarily made to reduce the impurities levels by minimizing air leakage and reducing oxygen content at furnace outlet when the impurities are high. In case of low air leakage and low oxygen content, efforts should be primarily made to reduce the power consumption of air separation units since it dominates the total power consumption. When compared to a reference monoethanolamine capture process, oxy-combustionhas a much lower specific primary energy consumption for CO₂ avoided (SPECCA) of 2.73 vs. 7.8 MJLHV/kgCO2 for the monoethanolamine capture.