Configuration Analysis of a Novel Zero CO2 Emission Cycle With LNG Cryogenic Exergy Utilization

Abstract

A novel liquefied natural gas (LNG) fueled power plant is proposed, which has virtually zero CO2 and other emissions and a high efficiency. Natural gas is fired in highly enriched oxygen and recycled CO2 flue gas. The plant operates in a quasi-combined cycle mode with a supercritical CO2 Rankine-like cycle and a CO2 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can be achieved at a temperature much lower than ambient, and high-pressure liquid CO2 ready for disposal can be withdrawn from the cycle without consuming additional power. The net thermal and exergy efficiencies of a base-case cycle are found to be over 65% and 50% respectively, which can be increased up to 68% and 54% when reheat is used. Cycle variants incorporating reheat, intercooling, and reheat+intercooling, as well as no use of LNG coldness, are also defined and analyzed for comparison. The approximate heat transfer area needed for the different cycle variants is also computed. Besides electricity and condensed CO2, the byproducts of the plant are H2O, liquid N2 and Ar.

A Novel Brayton Cycle With the Integration of Liquid Hydrogen Cryogenic Exergy Utilization

“…In HEX, the heat transfer is from the turbine exhaust (9-10) to the cold evaporated H 2 (16)(17) with the average E = 0.33. The exergy exchange is more complex; it can be divided into two sections: in the lower temperature section with both E d and E a < 0 (E d × E a > 0), the exergy is transferred from H 2 to the turbine exhaust, while in the higher temperature section, E d > 0 and E a < 0 (E d × E a < 0), both H 2 and the turbine exhaust loose exergy to the environment.…”

“…Deng et al [9] proposed a nitrogen gas turbine cycle, in which the LNG cryogenic exergy was used not only for power generation, but also for CO 2 separation and recovery from the main combustion products. We have proposed and analyzed a novel CO 2 zero emission system integrated with an LNG evaporation process [16,17], which is operated by a CO 2 quasi-combined two-stage turbine cycle with methane burning in an oxygen and recycled CO 2 mixture.…”

An Advanced Oxy-Fuel Power Cycle with High Efficiency

“…The high-temperature fluid (20) exiting the combustor at a mean temperature of 1300 8C is expanded in the IPT. The flow(21), after that, is reheated by firing with additional CH 4 and O 2 in the second combustor. The reheat pressure was set to 9.03 bar.…”