| The key technology of natural gas pipeline commissioning is the replacement process of natural gas. No matter in China or abroad, studies on production technology of pipe replacement are few at present. Basically, we can’t find the research achievements of related technology system. For the long distance pipeline which has been put into operation, the amount of nitrogen required in the production process of replacement of long distance pipeline is mainly obtained in site according to experiences in the process of production. The commissioning of the pipeline replacement generally takes a conservative approach, which will lead to blindness. That means the large amount of usage of nitrogen to ensure safe production. And this operation is not only very irrational, but also is a great waste of nitrogen. In accordance with the relevant requirements of "Natural Gas Pipeline Commissioning trial standards" and other domestic and foreign experience of pipeline putting into operation, how to ensure the safety of natural gas pipeline replacement or the orderly organization of the whole process is the key to production. The difficulty lies in how to effectively separate the air from the gas in order to prevent the formation of explosive mixtures (natural gas explosion limit is within the range of5%to15%). The replacement process requires low cost, simple operation, scientific, economic, and efficiency and safety. In this paper, pipeline commissioning process of pipeline from Yulin to Jinan has been discussed, and it comes to a set of suitable commissioning technology for the long distance natural gas pipeline. Furthermore, it provides the basis for Yuji pipeline commissioning safety operational decisions.This paper is divided into5parts:(1) The introduction.It elaborates the research background and significance of Yuji Pipeline Commissioning, investigates and analyzes the research status at home and abroad of pipeline commissioning replacement process, and made a comparative analysis of production technology at home and abroad, gives the research goal and content.(2) Yuji pipeline replacement and commissioning program design.Do domestic and international natural gas pipeline replacement technology research analysis, comparative analysis, to give the various strengths and weaknesses and the scope of application of the replacement methods. And do analysis of replacement order in order to determine the Yuji line replacement process, replacement order, the preparatory condition before commissioning.(3) The research of the gas mixing rule in Yuji pipeline commissioning replacement process.Through the application of FLUENT software simulated the mixing rules of nitrogen gas. In this paper, the simulation is carried out by using the "component transmission model" of chemical model. And the data derived from the FLUENT software, further use of EXCEL software to complete image processing data. Derived from the final image we can directly observe changes and developments or trends of the factors affecting mixed gas pipeline length, these major factors such as:temperature, diameter, and length and flow rate. Finally it summed up the gas mixing rule for Yuji pipeline in operation period.(4) Theoretical analysis and determination of key parameters in the replacement commissioning process of the Yuji pipeline.Methods to determine key parameters in the process of nitrogen replacement and natural gas replacement are analyzed separately. In order to determine the key parameters of Yuji pipeline replacement process, including the injection capacity of nitrogen, the nitrogen storage interval, natural gas source, replacement rate etc. At the same time the replacement interface detection and replacement steps are determined.(5) Risk identification and emergency measures of Yuji pipeline commissioning.Risk identification methods and accident types that may occur in the pipeline commissioning process are studied. Give the scheme of various accidents emergency repair, and HSE requirements in the commissioning process. |
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