Research On Cold Energy Recovery And Storage With Ethanol In The Gasification Process Of L-CNG Fueling Station

With increasing environmental requirements and gradual adjustment of energy structure,natural gas consumption is quickly increasing and gas consumption associated industries are rapidly developing.L-CNG fueling station provides compressed natural gas(CNG)by firstly pressurizing LNG and then heating it to CNG.This article investigated using cold energy of LNG regasification process to recover oil vapor.First of all,several common ways of LNG cold energy recovery and reuse were introduced,and a clear comparison analysis about four main oil vapor recovery technologies were given.By combining the two with the thermal energy storage,utilizing LNG cold energy in the process of the oil vapor condensation unit could achieve the goal of energy conservation and environmental protection.The phase transition temperature should be lower than-110°C to meet the requirement of the condensation process.Ethanol,which was selected as the phase change material of cold energy storage after comparing and analyzing some organic material,and liquid nitrogen,as the proper substitute of LNG in the laboratory,were used to simulate the cold energy process.A two-dimensional horizontal circular tube model was used to conduct a numerical analysis and calculation.The result indicated that natural convection has an obvious contribution in the solidification process of ethanol.A visual solidification experiment system was built with the purity of 99.7% ethanol.The double-walled organic glass circular tubes were used for visualization.Solid ethanol was observed in the tube and temperature distribution was measured.It was similar to paraffin in shape and color.Ethanol firstly freeze on the bottom of the fin,then grow and spread along the flow direction and around the surface.Ethanol grew different shapes in different flow rates of cold fluid.Besides,temperature distribution in different positions indicated that temperature stratification was produced in the certain range during the solidification process.There was a sudden fall of temperature near the freezing point and temperature change gradually flattened.Moreover,the experiment result coincides with some numerical result.The natural convection promoted solidification process,and as temperature decreased,the influence strengthened and then weakened.