Development of precooling model and calculation of precooling parameters for large LNG storage tank
Precooling operation is the most critical step before the commissioning of large Liquefied Natural Gas(LNG)storage tanks.The control of the amount of precooling agent,overall precooling duration,and cooling rate of various components of large storage tank is an important guarantee for the smooth precooling operation of large LNG storage tanks.Leveraging on a major LNG receiving terminal project,this study aims to accurately calculate the consumption of the precooling medium.The research focuses on the most complex large LNG storage tank of the project taking into account various factors,including the variation in specific heat capacity of cold insulation materials,daily evaporation from the tank,and heat loss in the precooling medium transportation piping.By developing a finite element model for numerical simulation,we are able to compute the necessary parameters within the precooling model.The calculation results of the precooling model show that by increasing the cooling rate during the precooling phase of the large LNG storage tank,there can be a significant reduction in both the amount of precooling medium required and the overall precooling duration.Additionally,this adjustment lessens the proportion of precooling medium lost due to heat loss.However,it is crucial to monitor the temperature differentials within the tank's components.Factoring in the heat loss from both the transportation piping and mechanical structure leads to an increased consumption of precooling medium,aligning more closely with on-site data,with a relative error of no more than 5%.The findings of this study offer guidance for actual precooling operations of large LNG storage tanks.
Large LNG storage tanksFinite elementPrecooling modelConsumption of precooling medium
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