Моделювання оцінки якості природного газу з використанням нечітких баз знань

Abstract

For the transportation of natural gas and use it as an energy carrier, on a municipal and industrial scale, it is necessary to qualitatively prepare and purify it, because the primary natural gas contains a large amount of droplets of moisture, heavy hydrocarbons and mechanical impurities, which can lead to the formation hydrates, corrosion, damage to process equipment, shortening the life cycle of the gas transmission system, and worst of all, the occurrence of gas pipeline emergencies. The paper presents a study of the influence of factors on the quality of natural gas at the stage of preparation (purification) of it for transportation to consumers. Such factors are found to be the Wobbe number higher, the heat of combustion higher, the relative density of natural gas purification from hydrogen sulfide, nitrogen, carbon dioxide, oxygen, mechanical impurities and moisture. The mathematical model of managerial decision making is proposed by the expert of the project on estimation and prediction of quality of natural gas with consideration of qualitative and quantitative excitatory factors of influence on it, based on the theory of fuzzy logic on linguistic variable. Phasification of fuzzy estimates of impact factors was performed, which made it possible to construct membership functions for linguistic variables describing the process of natural gas preparation at the system level. To determine the quality of fuel on the basis of expert-linguistic information in the form of "IF - THAT" rules, a fuzzy matrix of knowledge was created and a system of fuzzy logical equations was obtained, which will allow to predict the process of purification of natural gas for transportation and its composition under different operating conditions of the gas transmission system to provide consumers natural gas of normalized quality. Gas quality assessment and forecasting have been carried out, which will increase the operational reliability of the gas transmission system and reduce the likelihood of gas accidents and ultimately affect the timely supply of gas and reduce the cost of gas pipeline repairs.