Research On The Pipeline Transportation Characteristics Of Liquid Carbon Dioxide At Low Temperture

The emissions of greenhouse gas CO₂ which is produced by industry and human has leading to global warming,and the survival of the human environment is getting worse.With the deepening of human awareness of the CO₂ and the improvement of the sense of crisis,CO₂ capture and storage?CCS?technology develops rapidly.Among them,the pipeline transportation is an important part of CCS technology.CO₂ can be transported in gas,liquid and super critical states,which are determined by the temperature and pressure of the pipeline system.This paper takes CO₂ pipeline between the injection stations to injection well in Changqing Oil Field as an example,the low temperature liquid CO₂ pipeline transportation is analysed.In this paper,the effects of gas impurities,like N₂,O₂,CH₄,H₂S,on the physical properties of liquid CO₂ are simulated.The pipeline temperature drop model is built on the base of Sukhov formula,writing temperature drop calculation program by using VB6.0software,and iterative approach is adopted to calculate the change of temperature along the pipeline.The influence of the parameters such as the season and the buried depth of the pipe on the temperature distribution of CO₂ pipeline are analyzed.Liquefied CO₂ transportation is often in high pressure and low temperature state,which will directly affect the soil temperature around the pipeline field,affect thenormal growth of crop,and it is even a threat to the safe operation of the water injection pipeline in oilfield.In this paper,the model of soil temperature field distribution is established and the finite element method is used to solve this model.By calculating the soil temperature field surrounding the liquid CO₂ pipeline and analyzing the influence on the soil temperature field when the CO₂temperature in pipeline starting point,the CO₂ flow rate,the pipe buried depth and other parameters change,we can understand the influence of liquid CO₂ pipeline on soil temperature field.By analysising the temperature fields along the axial direction of the pipeline,the minimum distance between water injection pipeline and low temperature liquid CO₂ pipeline is determined,thus the time and range of the influence of the buried depth of low temperature liquid CO₂ pipeline on the surface crops are also determined.This will provide the scientific evidence for the optimization of pipeline construction,and achieving the purposes on guidancing the safe operation of low temperature liquid CO₂ pipeline,saving energy and reducing the cost of pipeline constrution.