Indexed by:期刊论文

Date of Publication:2022-06-29

Journal:Journal of Safety and Environment

Volume:20

Issue:3

Page Number:870-877

ISSN No.:1009-6094

Key Words:"safety engineering; buried pipeline release; carbon dioxide; dry ice ball; temperature evolution"

CN No.:11-4537/X

Abstract:Based on the industrial-scale experimental surface-below buried pipeline,we have done an experiment of the dense CO_2 release by using the experimental device mainly comprising a principal pipe,a pneumatic valve,a connecting pipe,a buried pipe and a sandbox.The experimental data to be measured has been arranged in a form of T-type thermocouple around the release orifice.At the same time,the temperature of the buried pipeline surface and the soil in addition to the dry ice ball and frozen soil ball are supposed to be able to be measured during the CO_2 release with 1 mm and 3 mm orifice.What is more,the increasing process of the volume of the dry ice hockey and the frozen soil balls have been laid out likely to be analyzed through the isotherm mapping.And,then,physical parameters of the initial sand in the sandbox have also been tested before doing the experiment so as to ensure the accuracy of the experiment.The results of the above experimental study show that the ellipsoid-like frozen soil balls formulated around the release orifice and the dry ice balls both exist inside the frozen soils.The dry ice accumulation may take place in all the directions of the pipeline.Nevertheless,in the leakage direction,the dry ice accumulation gap and the leakage time intends to show a logarithmic function relation.With the increase of the orifice size,the volume of the frozen soil and the dry ice tend to turn to bigger and bigger with the speed of the volume increase getting faster and faster.And,meanwhile,the temperature at the surface of the frozen soil may increase first and then decrease to get stable at last.In addition,the temperature on the soil may experience 4 stages: i.e.from being constant to get to decrease slowly,and,quick decrease to get stabilized.What is more,the closer to the release orifice,the lower the temperature would be getting to.And the greater the release orifice,the greater the low temperature area would appear.Besides,the temperature drop and the temperature drop rate in the leakage direction should be greater than that of the opposite direction to the leakage.Thus,correspondingly,the increase of the diameter of the soil may lead to the broadened drop rate in the temperature of the soil area due to the greater temperature change.

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