利用LNG冷(火用)的准零CO_2排放循环探析

NEW NEAR-ZERO CO2 EMISSION THERMAL CYCLES WITH LNG CRYOGENIC EXERGY UTILIZATION

本文研究利用LNG冷(火用)来完善燃用它的热机性能,既提高了效率,又能回收用LNG燃料热机的唯一主要排放-CO_2。这种系统的温度区间横跨大气温度,会有很多新的特点值得探索。作为前期研究,本文建议了两种新循环,分别基于Brayton循环与超临界Rankine循环,且分别适用于LNG超临界及亚临界汽化过程。文中对此两种循环进行了分析计算与讨论,说明建议是可行的,热机效率可达60％以上,且同时基本回收所有燃烧产生的CO_2。

In this paper, new cycles are proposed which integrate LNG cryogenic exergy utilization and CO2 recovery. They use no cooling water, and on the contrary, allow the easy removal and recovery of water and CO2 generated from combustion to thereby offer both energy saving and greenhouse gas emission mitigation. The cycle working temperature region crosses over the ambient temperature, thus they have some new features unlike those of the conventional power cycles. The proposed Brayton cycle and supercritical Rankine cycle are simulated and compared, with the integration of LNG supercritical and subcritical evaporation processes, respectively. The results indicate that the proposed cycles indeed reduce CO2 emissions significantly with very attractive thermal performances, able to attain thermal and exergy efficiencies above 60% and 50% respectively.