Guidelines for the application of reliability-based design and assessment to natural gas pipelines were developed under PRCI sponsorship in 2005. The methodology underlying these guidelines has since been adopted as a non-mandatory Annex in the CSA Z662 standard (Annex O). Following the code in CSA Z662 Annex O, the reliability analysis of an in-service X80 pipeline in North-West China is performed using Monte Carlo technique. In this paper, the distributions of basic input parameters such as loadings, material property is derived based on the data collected from industrial practice. And the analysis of limit states, such as yielding of the defect-free pipeline, bursting of the defect-free pipeline, local buckling due to restrained thermal expansion and excessive plastic deformation, is proceeded based on these distributions. The core of reliability analysis lies in the selection and correction of limit state functions. The modification and extension of limit state models is very significant to accurately calculate probability of failure of different natural gas pipelines, so the limit state models are refined to adapt to the specific work conditions in China. A Monte Carlo reliability analysis framework capable of incorporating the data of industrial practice and limit state models has been developed and applied to the evaluation of the X80 natural gas pipeline, then a practical approximation is developed by using Monte Carlo simulation results. A practical example of an in-service X80 natural gas pipeline is presented to illustrate the availability of the reliability analysis. Furthermore, results generated by different basic input parameters in a limit state function are compared. The sensitivity analysis shows the degree of influence of various basic parameters.
Abstract At present, China has a developing natural gas market, and ensuring the security of gas supply is an issue of high concern. Gas supply reliability, the natural gas pipeline system’s ability to satisfy the market demand, is determined by both supply side and demand side, and is usually adopted by the researches to measure the security of gas supply. In the previous study, the demand side is usually simplified by using load duration curve (LDC) to describe the demand, which neglects the effect of demand side management. The simplification leads to the inaccurate and unreasonable assessment of the gas supply reliability, especially in high demand situation. To overcome this deficiency and achieve a more reasonable result of gas supply reliability, this paper extends the previous study on demand side by proposing a novel method of management on natural gas demand side, and the effects of demand side management on gas supply reliability is analyzed. The management includes natural gas prediction models for different types of users, the user classification rule, and the demand adjustment model based on user classification. Firstly, An autoregressive integrated moving average (ARIMA) model and a support vector machine (SVM) model are applied to predict the natural gas demand for different types of users, such as urban gas distributor (including residential customer, commercial customer, small industrial customer), power plant, large industrial customer, and Compressed Natural Gas (CNG) station. Then, the user classification rule is built based on users’ attribute and impact of supplied gas’s interruption or reduction. Natural gas users are classified into four levels. (1) Demand Fully Satisfied; (2) Demand Slightly Reduced; (3) Demand Reduced; (4) Demand Interrupted. The user classification rule also provides the demand reduction range of different users. Moreover, the optimization model of demand adjustment is built, and the objective of the model is to maximize the amount of gas supply for each user based on the classification rule. The constraints of the model are determined by the classification rule, including the demand reduction range of different users. Finally, the improved method of gas supply reliability assessment is developed, and is applied to the case study of our previous study derived from a realistic natural gas pipeline system operated by PetroChina to analyze the effects of demand side management on natural gas pipeline system’s gas supply reliability.
Many algorithms and numerical methods, such as implicit and explicit finite differences and the method of characteristics, have been applied for transient flow in gas pipelines. From a computational point of view, the state space model is an effective method for solving complex transient problems in pipelines. However, the impulse output of the existing models is not the actual behavior of the pipeline. In this paper, a new lumped parameter model is proposed to describe the inertial nature of pipelines with inlet/outlet pressure and flow rate as outer variables in the state space. Starting from the basic mechanistic partial differential equations of the general one-dimensional compressible gas flow dynamics under isothermal conditions, the transfer functions are first acquired as the fundamental work. With Taylor-expansion and a transformation procedure, the inertia state space models are derived with proper simplification. Finally, three examples are used to illustrate the effectiveness of the proposed model. With the model, a real-time automatic scheduling scheme of the natural gas pipeline could be possible in the future.
With the development and popularization of gasfired power generation and P2G technology, the electrical system is becoming more and more closely connected.Gas energy is a good form of energy storage or transition in integrated energy system.However, few theoretical studies conduct on the coupling development of gas network and integrated energy network from the perspective of natural gas network planning.Improper natural gas system infrastructure planning will lead to waste of resources and environmental impact.Therefore, this paper aims to improve the efficiency of gas transport from the perspective of gas pipeline network planning and promote the development of low carbon economic coupling of gas integrated system (IGES).We propose a multi-dimensional natural gas network system planning strategy that enhances the link between it and electrical system to solve how to convey natural gas from P2G station into pipelines.The strategy simulates the planning behavior of natural gas pipeline network company under the background of integrated electricity and gas system and analyzes the economic and environmental benefits of the new strategy.The results show that a feasible planning scheme can improve the economic benefits of gas network operators and reduce the carbon emissions.Based on these analyses and conclusions, recommendations are made for policy formulation and planning directions at different levels.In summary, the new gas pipe network planning strategy will help to enhance the importance of gas pipe network in the IGES and promote energy conservation and environmental protection in the energy industry.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(144 450 300)'/%3e%3cuse xlink:href='%23a' transform='rotate(216 450 300)'/%3e%3cuse xlink:href='%23a' transform='rotate(288 450 300)'/%3e%3c/svg%3e)