Reliability Evaluation Study Of The Long Distance Natural Gas Pipeline System

The reliability of long distance natural gas pipeline system will be influenced by many reasons including pipe failure,compressor failure and the fluctuation of task flow rate.In order to evaluate the influence to the system reliability and seek corresponding measures to enhance the reliability,theoretical research is conducted in this paper.Based on the definition of the reliability index,this paper proposes a reliability evaluation methodology.With the help of SPS software,adopt the proposed method to evaluate the reliability of the pipe unit,compressor unit and pipe-compressor system respectively.For the pipe part,limit state functions from ASMEB31 G,CSAZ662,DNVF101 and PCORRC are used as the failure criteria and Monte Carlo as the simulation method to calculate the probability of failure.The result from different standards are compared.For the compressor part,the universal generating function is used to evaluate the compressor system reliability and the shortcomings of different functions are revealed.For the pipe-compressor system,the reliability evaluation strategy is proposed,and the reliability distribution with time is figured out.Moreover,for different corrosion defects,according to calculations and analysis of typical months from different reliability levels,preliminary suggestions of maintenance routine are put forward.Considering the reliability of the pipeline system,this paper provides an optimization model for the standby compressor scheme selection.In terms of characteristics of the optimization variable,genetic algorithm with binary coding is used to optimize this model.In this part,adopt both enumeration and genetic algorithm to find the standby compressor scheme of a domestic pipeline which only owns 4 compressor stations.The same scheme can be obtained.The result can be used to illustrate the effectiveness of the genetic algorithm in solving this problem and the correctness of the code.Based on the above mentioned study,apply the optimization model and the method to the GASBOL pipeline which owns 10 compressor stations.As a consequence,a new scheme is obtained and it is better than the reference mentioned three typical schemes when we use the same measurement.