Research On Waste Heat Recovery Power Cycle Technology Based On LNG Cold Energy

With the growth of the world's population,the global demand for energy has gradually increased,and the transformation of the energy structure has become more and more urgent.Liquefied natural gas(LNG)is a clean energy source that accounts for a large proportion of the transformation process.China's imports of LNG show a year-on-year increase.At the same time,the number of LNG receiving stations has also increased year by year,and many receiving stations have also begun LNG cold energy utilization projects.China's LNG cold energy single utilization technology is becoming more mature,but the overall utilization rate is not high.In order to improve the LNG cold energy utilization rate,stepwise utilization of cold energy is one of the important ways.The use of LNG cold energy and the recovery of low-and medium-temperature waste heat resources have been hot topics of research.How to use these two types of complementary heat and cold energy to reduce the loss of cold energy and increase the recovery rate of waste heat resources are of great benefit to the rapid advancement of economic and ecological civilization.The systems based on Rankine cycle and Kalina cycle have been proposed in this paper provides an economical,environmentally friendly and efficient solution for the use of cold energy and waste heat resources.An energy system that integrates power generation,cooling,heating,and CO₂ capture can meet the needs of users in all aspects,and achieve the effect of energy saving and emission reduction.This research content provides a great reference for improving energy efficiency and slowing down the global greenhouse effect.Based on these contents,the research content of this paper is mainly divided into:(1)This article uses Aspen Hysys software for simulation and provides a basis for process calculation based on the Peng-Robinson equation,the effects of different gasification pressures on the physical properties of LNG are analyzed.The segmentation law of LNG gasification curve under subcritical pressure and supercritical pressure is discussed and analyzed.It is concluded that LNG cold energy under different evaporation pressures should be used in stages.(2)A dual-loop-kalina cycle power generation system combining CO₂capture,cooling,and reuse of circulating water was constructed.By analyzing various thermodynamic parameters in the system,the circulation system reaches an optimal working condition.At the same time,by adjusting the narrow point temperature difference,the damage of the evaporator is greatly reduced.Compared with other waste heat resource recovery and utilization technologies,it shows a good effect in terms of CO₂ capture,and the recovery of recycled water significantly reduces the water consumption of the system.(3)Constructed two systems that integrate cooling,heating,power generation and CO₂ capture.Based on the Kalina cycle(KC),the system combines Regenerative Organic Rankine to bring back heat in one system.Cycle(RORC),another system coupled with Regenerative Dual Organic Rankine Cycle(RDORC).The boiler exhaust gas generated by SOFC is used as the heat source,and the cold energy generated by the clean energy LNG gasification is used as the cold source.The system can recycle the waste heat source and reduce the temperature to the ambient temperature.At the same time,the heat source utilization rate can be improved through power generation,cooling and heating.In the process of LNG gasification,CO₂ can also be captured in waste heat sources to achieve the effect of slowing down the greenhouse effect.Through a series of heat exchange with heat sources,LNG can be raised to room temperature and used directly for gas supply in urban pipe networks,without the need for energy and gasification to save energy.In addition to discussing the thermodynamic parameters such as net output work and plutonium efficiency of the two systems,this paper also analyzes various economic parameters under different physical property parameters,and discusses the environmental parameters of the two systems.