A novel near-zero CO_2 emission thermal cycle with LNG cryogenic exergy utilization

摘要

A novei liquefied natural gas (LNG) fueled power plant is proposed, which has virtually zero CO_2 and other emissions and a high efficiency. Natural gas is fired in highly enriched oxygen and recycled CO_2 flue gas. The plant operates in a quasi-combined cycle mode with a supercritical CO_2 Rankine-like cycle and a CO_2 Brayton cycle, interconnected by the heat transfer process in the recuperation system. By coupling with the LNG evaporation system as the cycle cold sink, the cycle condensation process can be achieved at a temperature much lower than ambient and high-pressure liquid CO_2 ready for disposal can be withdrawn from the cycle without consuming additional power. The net energy and exergy efficiencies are found to be over 65 and 50%, respectively. In the case computed (but not optimized), the required total heat exchanger area is estimated to be about 460 m~2/MW electricity produced. Besides electricity and condensed CO_2, the byproducts of the plant are H_2O, liquid N_2 and A_r.