Preparation Of Cryogenic Insulated Cylinders Inspection Station And Research On Evaporation Rate Testing

With the rapid development of industry,cryogenic insulated cylinders are widely used in industry,medicine,food and so on.Low temperature liquefied gas has the characteristics of low temperature and high gas-liquid ratio.Especially for flammable and combustible low-temperature liquid medium,leakage will lead to fire or explosion accidents,which is very harmful.In order to ensure the safe use of cryogenic insulated cylinders,supporting the corresponding cryogenic cylinder inspection station has become an important support for the development of cryogenic industry.In addition,evaporation rate measurement is an effective method to monitor the insulation performance of cryogenic insulated cylinders,and it is also one of the main items for regular inspection of cylinders.However,there are some problems in the current evaporation rate test methods,such as the disunity of filling rate,the long standing time and the influence of environmental factors.In this paper,starting from the preparation of cryogenic insulated cylinders inspection station and improvement of evaporation rate test method,the correction method of evaporation rate test is obtained by comparative analysis and experimental data verification.The main research contents and conclusions are as follows:This paper analyzes the necessity and feasibility of Dongguan Institute of special equipment testing and Research Institute of Guangdong Province for the construction of cryogenic insulated cylinders inspection station,selects the main equipment and instruments required for testing and the technical parameters of low-temperature pipeline,and completes the preparation for the construction of cryogenic insulated cylinders inspection station.The results show that under the same environmental conditions and filling pressure,the evaporation rate of the same gas cylinder in the hot state is larger than that in the cold state on the first day,and is smaller than that in the cold state at the beginning of the second day;under the same environmental conditions and hot state,the experiments with different filling pressure show that the evaporation rate of the gas cylinder is lower at high filling pressure The filling pressure should be small.No matter whether the cylinder is in cold or hot state or under different filling pressure,as long as the liquid nitrogen is filled to 95% of the effective volume of the cylinder at standard atmospheric pressure(101.325 k Pa),the static equilibrium time can be shortened from 48 h to 24 h.In order to effectively reduce the mutual interference between the influencing factors of evaporation rate,this paper studies and analyzes the influencing factors one by one by using the control variable method by building a constant temperature and humidity chamber.It is found that the higher the ambient temperature is,the greater the evaporation rate is;the greater the environmental humidity is,the greater the evaporation rate is;and the smaller the cylinder volume is,the greater the humidity influence is;under normal pressure,the relationship between environmental pressure and evaporation is inversely proportional Case relationship.The concept of "equilibrium filling rate" is proposed,and the evaporation rate decreases with the decrease of equilibrium filling rate.In order to eliminate the influence of filling rate on evaporation rate,this paper proposes a modification of evaporation rate measurement method based on equilibrium filling rate.On the basis of the original calculation method of evaporation rate,the correction coefficient of equilibrium filling rate is used to correct.The deviation between the revised evaporation rate and the evaporation rate under the standard rated filling rate is less than 10%,which meets the engineering requirements.The method of equilibrium filling rate correction coefficient method is adopted in the study,which can reflect the evaporation rate requirement under the rated filling rate with less equilibrium filling rate(i.e.liquid level),which saves the liquid nitrogen required for the test,reduces the detection cost and improves the detection efficiency.