Research On Research On Power Generation Of LNG Cold Energy Based On Organic Rankine Cycle (ORC)

Energy is the source of power and it plays a very important role on the development and progress of society. The use of fossil energy has led to the rise in global temperatures and serious environmental pollution, therefore, development and utilization of clean energy is the inevitable choice of our humanity. Due to the high energy efficiency and low impact on environment of LNG (liquefied natural gas),it is widely used in 21st century.LNG releases lots of cold energy during its gasification process. Therefore, LNG cold energy utilization has become a subject which is worth researching. This paper is based on the idea to study how to recycle LNG cold energy and the following work was finished:Read, studied and summarized a large number of domestic and foreign literature about LNG cold energy utilization. Based on the analyzed the problems on LNG cold energy power generation process and working fluid selection, this paper proposed a novel LNG cold energy utilization program.LNG at temperature-162℃ is firstly applied to air separation plant, and then flows into organic Rankine cycle power generation system at temperature -100℃The working fluid operating temperature based on LNG cold organic Rankine cycle power generation system, especially the condensing temperature is significantly lower than that in conventional power generation system. Selection of the appropriate working fluid has become a very critical issue. On the basis of the environmental performance of the working fluid, physical and chemical characteristics, safety features and thermodynamic properties of the initial screening some suitable the working fluid is selected, and then analyzed the performance of the system using these refrigerants to select the most suitable system efficient working fluid. Results show that R227ea the best working fluid 1 in the top cycle, R116 for the best working fluid 2 in the bottom cycle.This paper established the thermodynamic model and thermo-economic model of LNG cold energy generation systems. The integrated indicators CPP (system net power cost) is introduced to evaluate the thermodynamic and thermo-economic performance.Parametric analysis has been performed to study the effects of evaporating pressure and mass flow rate The net power output, thermal efficiency, exergy efficiency, cost per net power output CPP are calculated to well evaluate the system thermodynamic analysis and deals with the optimization of power system. Under the optimal working condition, the thermal efficiency of the present two-stage ORC can be raised to 25.64% with exergy efficiency at 31.02%. The net power output, Wnet, is 1.78MW and the cost per net power output CPP is 5,1$/W.