ASSESSMENT OF ACCURACY OF DETERMINING GAS RESERVES IN PIPES UNDER CONDITIONS OF INCOMPLETE LOADING OF THE GAS TRANSPORTATION SYSTEM

Abstract

The problem of determining the amount of gas in the sections of the linear part of the gas transportation system under the conditions of non-stationary mode of its operation is considered. In the conditions of war and post-war times, non-stationary processes in gas transport systems are characteristic of conditions of increased emer-gency and changes in the directions of gas flows and consumers. Therefore, the estimation of gas volumes in gas pipeline sections has to be carried out under conditions of non-stationarity, which leads to significant errors in the calculation results. In conditions of non-stationarity, fluctuations in gas pressure along the length and in time are observed, due to which the average pressure differs from the value found by stationary methods. The use of frequency methods, which is considered in the tasks of applying impedance methods in the calculation of non-stationary processes, to estimate the frequency range of gas pipeline operation, to obtain simplified methods of analysis of gas pipeline modes, numerical methods of applying operational equations, when analyzing the opera-tion of a gas pipeline by methods of statistical dynamics, equations of unsteady gas movement along a gas pipe-line. The frequency and amplitude of pressure fluctuations caused by disturbances in gas flow parameters are characteristics of a non-stationary process, therefore there should be a relationship between the amplitude-frequency characteristics and the non-stationarity criterion. The analysis of non-stationary processes in the gas pipeline caused by the change in gas flow was carried out on the basis of analytical modeling methods. As a model, the differential equations of gas motion and continuity, supplemented with stationary initial conditions and boundary conditions of the second kind, were used. Appropriate analytical solutions of pressure fluctuations and flow in the gas pipeline along the length and in time were obtained. The conducted analysis shows that the error in determining the volume of gas in the pipes under non-stationary conditions can be significant and must be taken into account. In this regard, a numerical amendment to non-stationarity of the regime when determining the amount of gas in the gas pipeline, which depends on the criterion of non-stationarity and which must be intro-duced into the calculation methodology.