Study Of LNG Cold Energy Power Generation System

The large population growth and rapid economic development since the21st century have led to a large amount of energy consumption.The problems of energy shortage,environmental degradation,and climate change caused by it have aroused widespread concern of people around the world.Natural gas has been recognized as one of the most promising clean energy sources in the21st century due to its huge unit heat value and low environmental pollution.LNG(liquefied natural gas),as a liquid form of natural gas,has a temperature of about-162°C and releases huge cold energy during the gasification process.How to use this part of cold energy is of great significance for energy conservation and emission reduction.From the perspective of rational and efficient use of LNG cold energy,combining LNG cold energy with gas turbine exhaust gas,based on the Rankine cycle,a LNG cold energy power system capable of capturing carbon at the same time as generating electricity was established.The influence of key thermodynamic parameters on the thermal performance of the system was analyzed in detail by using Aspen Plus software.The results show that increasing the condensing pressure of organic Rankine cycle condensing pressure has a positive impact on net output work and exergy efficiency,and the best net output work and exergy efficiency existed when the vapor circulating condensing pressure was2.9mpa.The increase of working medium R125 flow had a negative effect on the net output work and exergy efficiency,while the water vapor flow was positively correlated with the net output work and exergy efficiency.Increasing CO₂ compression pressure increases the amount of CO₂ capture and decreases the system's net output work.According to the integration principle of the total energy system,this paper designs a combined cooling and power supply system that combines the residual heat of internal combustion engine and LNG cold energy.The influence of key parameters on the thermal performance and economic performance of the system was analyzed in detail.The results show that the internal combustion engine waste heat recovery rate can reach 89%,and the LNG cold energy cold exergy efficiency can reach 43%.The increase of the turbine inlet temperature and the decrease of the expansion pressure ratio of the Brayton cycle are beneficial to the improvement of the thermal performance of the system.The Kalina cycle expansion pressure ratio decreases,and the economic performance of the system becomes better.The vapor inlet pressure of cryogenic refrigeration cycle is inversely proportional to the refrigerating capacity and the mass flow of working medium is positively proportional to the production cost of electric power.