Integrated Modeling And Optimization Of A Novel Oxy-Fuel Power System With LNG Cold Energy Utilization

With the development of social economy and the adjustment of energy structure, natural gas has been widely used as a high efficient and clean energy.At present, CO₂ emission is one of the biggest challenges for protecting environment. Now, Oxy-fuel combustion is the only way to capture CO₂ commercially, but it would increase the cost of power generation obviously. Constructing a reasonable oxy-fuel power system with LNG cold energy is one of the most effective methods. The thesis is to study how to use LNG cold energy to improve power generation efficiency.With the Aspen Plus software, we built the model of the proposed natural gas oxy-fuel power system with LNG cold energy and evaluated its performances. The results showed that the specific power consumption of high pressure O₂ was 234.7 k W·h·t-1, 20.6% lower than that of the traditional process, while the specific power consumption of liquild product was the half of the traditional process. The generating efficiency of the proposed cycle reached 54.4%, 3.9% more than that of the conventional power process. Meanwhile, 96.5% CO₂ could be recovered. The SPECCA of the proposed natural gas oxy-fuel power system was 1.72 MJLHV·kg-1 CO₂ while the SLNCC was 1.8 kgLNG·kg-1CO₂. Compared with the same type progress, it could reduce CO₂ emission with less electricity and LNG cold energy.In addition, this thesis presents the critical parameters analysis results of the proposed natural gas oxy-fuel power system with LNG cold energy. The study shows that: Producing more liquid product could reduce the specific consumption of the high pressure O₂ as less O₂ was compressed; The high turbine inlet tempreture and pressure ware beneficial to improve power generating efficiency, as well as the tempreture and pressure of the main steam; The optimum concentration of the high pressure O₂ was from 95% to 97%; The SPECCA reached its minimum level when the CO₂ recovery rate was 96.5% and the concentration of the high pressure O₂ was 95%.