Effect of irradiation in the visual and infrared spectral regions on nuclear magnetic relaxation parameters of protons in oil products

Abstract

538.955:538.958 The influence of laser and non-coherent irradiation on the state of oil components has been studied at wavelengths of 630 and 1825 nm, respectively. New results reflecting changes in structural-dynamic parameters of the molecular motion as a function of exposure time have been obtained. The variations of NMR parameters during NIR irradiation of an oil sample prepared with the addition of paraffin (docosane) seem to be connected with "washing out" of these nanodimensional structures and can be explained theoretically in terms of the phenomenological description of the energy-level population behavior. The method of NMR relaxometry used in parallel with laser and non-coherent radiation in the NIR spectral region has been shown to enable one to readily determine oil components that are difficult to estimate by conventional techniques.Introduction. Existing analytical methods (IR spectroscopy, x-ray structure analysis, mass spectrometry) are poorly suited for rapid analysis of nanostructures that affect the quality of fuels and dispersed oil systems because of the need to prepare samples. High-resolution NMR requires a sophisticated instrument and also cannot provide information about high-molecular-weight oil compounds (HMWC) and cannot be used conveniently for analysis. However, analysis and rapid monitoring of HMWC in fuel and crude oil are necessary for optimization of industrial processes, prevention of man-made accidents, and protection of the environment. NMR relaxometry has such capabilities. The potential of this method was demonstrated using several physical chemical properties of oil, residuals, and asphalts as examples [1,2]. It was also established that component concentrations (asphaltenes and resins) found from NMR relaxometry differed from the component composition determined according to GOST 2177-99 (ISO 3405-88). This was due to hindrance of the molecular motion of HMWC structural fragments and shortening of the relaxation times below the capability limits of the NMR instrument. We proposed [3] "heating up" the molecular motion of the HMWC fragments by irradiation at their absorption wavelength, thereby increasing the frequency and amplitude of molecular motion and achieving a selective increase of the relaxation times and their observation.Our goal was to study structural and dynamic changes of molecular motion NMR parameters as a function of temperature and irradiation time in the visible and near-IR (NIR) regions and to increase the selectivity and sensitivity of the analysis of oil components.Experimental. We studied oil samples from the Romashkin deposit with densities ρ = 867-938 kg/m 3 and asphaltene concentrations 3.30-6.70 mass %. In particular, oil of density ρ = 867.5 kg/m 3 had kinematic viscosity ν 20 = 42.9 cSt and concentrations of oil 51.2%; benzene resins, 17.4; alcohol-benzene resins, 7.1; asphaltenes, 3.3; sulfur, 1.6; and paraffins, 3.1. We also studied samples of this oil to which various amounts of the paraffin docosane (C 22 H 46 ) of density ρ = 778 kg/m ...

Methodology for assessing the environmental characteristics of various methods of generating electricity

“…In recent years, there has been a significant increase in the consumption of primary energy and electricity [1][2][3][4][5][6][7][8][9]. Currently, the most demanded for energy production are oil, coal, gas and uranium [3,4,5,[10][11][12][13][14][15]. In the coming decades, they will remain the main sources of energy -30, 23, 24, 12 %, respectively.…”

Особенности Исследования Состояния Текущей Среды Методом Ядерного Магнитного Резонанса

“…В настоящее время явление ядерного магнитного резонанса (ЯМР) широко применяется для решения различных задач, связанных с проведением научных исследований, для контроля состояния конденсированных сред на промышленном производстве и т. д. [1][2][3][4][5]. Это связано с тем, что проводимые с использованием метода ЯМР измерения не вносят необратимых изменений в физическую структуру и химический состав исследуемой среды [4][5][6][7][8][9][10] в отличие от случаев применения оптических, ультразвуковых и других методов [10][11][12].…”

“…Исследования потоков жидких сред являются наиболее сложными, особенно при турбулентном режиме их течения [1,2,4,[13][14][15][16]. В ряде экспериментов, в которых используется текущая жидкость, в процессе всего исследования необходимо контролировать как ее расход q, так и ее состояние.…”

“…Проведенные нами исследования показали, что в большом числе случаев (особенно для смесей жидких сред) измерения одного времени T 2 недостаточно для определения состояния среды[2,9,13]. Для надежного и эффективного контроля состояния текущей среды необходимо измерять две константы релаксации.…”

Determination of dispersity of aqueous emulsions of hydrocarbons by nuclear magnetic resonance relaxometry

“…We previously demonstrated the possibilities of the nuclear magnetic resonance (NMR) method in analysis of different physicochemical and technological characteristics using different examples in [9][10][11][12][13][14][15][16][17][18][19][20]. Development of the NMRR method is needed for monitoring the droplet size distribution in emulsions of high-viscosity crude oils (bitumens) and the water concentration during formation and breakdown of the emulsions, and also to establish correlations between the NMRR parameters and the droplet size distribution in as broad a hydrocarbon density range as possible.…”