Romaniv V. An improvement of the optical method for estimating the energy parameters of natural gas

The dissertation is devoted to the solution of an important scientific and applied problem - an improvement of the optical method for estimating the natural gas's energy parameters by developing a new and improving existing methods and means of measuring the energy characteristics of natural gas. The analysis of modern methods and existing normative support for estimating energy indicators of natural gas is carried out. It is proved that the volumetric heat of natural gas combustion and its energy should be determined precisely by its component composition by measuring instruments based on infrared (IR) spectroscopy. The research was conducted for the detection of hydrocarbon components of natural gas and the methane, ethane and propane of the band with centers of 1.65; 3.06 and 3.36 ?m were chosen. The researches of propagation processes of infrared radiation in natural gas and fiber optic channel and reflection and scattering on bounding surfaces are carried out. Obtained results were putted as the basis of the developed three-color scheme for measuring the concentration of natural gas components to increase the sensitivity of the optical control method. There was proposed an adaptive estimation method for higher hydrocarbon components concentrations of natural gas basing on statistical analysis of the natural gas component composition of the main gas deposits in the world and Ukraine. The essence of the method is based on the selective fragmentary processing of statistical data in conjunction with the method of median centers with the subsequent calculation of functions of polynomial, which allowed to implement the algorithm for measuring the volume concentration of natural gas components, that means the direct simultaneous measurement of the three main components (СН4, С2Н4, С3Н8) in strips having a minimal impact on each other, and in determining the total concentration of higher hydrocarbon components. An offered method was used as the basis for the development of a structural scheme and algorithm for the functioning of the natural gas monitoring system. There was developed a software in order to implement the algorithm of functioning. In this case, the relative error of the concentration determination for the higher components of С4Н10+ does not go beyond the limit ± 7%. There has been improved the device for transformation and presentation of information in turbine gas meters, which are a part of measurement system of natural gas energy. A projected device while forming and transmitting messages about the movement of a measuring element eliminates the possibility of repeating the same signals in information blocks, and can also effectively reproduce the data in case of loss the information. It is shown that the developed system provides control of natural gas energy with a relative expanded uncertainty of control which is equal 5.87%. The industrial testing of the experimental model were carried out basing on "Ivano-Frankivsk gas", which confirmed the correctness of theoretical conclusions, recommendations and practical decisions.