Vol 335, No 10 (2024)
Articles
Solution of the problem with a small parameter in suspension filtration in a porous medium
Abstract
Relevance. The necessity to calculate the changes in filtration properties during injection of suspensions for subsequent forecasting of technological parameters of wells. This calculation is complicated by the presence of different-scale effects, since the penetration depth of dispersed particles is orders of magnitude smaller than the characteristic dimensions of the formation. These effects have not been studied in detail before.
Aim. To analyze the effect of a small parameter on the behavior of flow characteristics using a mathematical model of suspension filtration in a porous medium.
Objects. Colmatation coefficient, filtration coefficient, distribution of concentration of dispersed particles in the formation, porosity, mathematical model of deep-bed suspension migration into a porous medium.
Methods. Numerical modeling, explicit finite-difference scheme, solution of a problem with a small parameter, introduction of dimensionless parameters, method of characteristics.
Results and conclusions. It is shown that the processes of conformance control and colmatation of a porous medium are described within the framework of a unified system of equations of deep-bed suspension migration into a porous medium. It is identified that the concentration of retained particles is a small parameter that allows reducing the complete system of equations of deep-bed suspension migration into a porous medium to a simplified form, in which the solution can be obtained analytically using the method of characteristics. The authors compared the solutions of the complete and simplified systems of equations of deep-bed suspension migration into a porous medium, indicating their compliance with an error of less than 4%. They obtained the distributions of the concentration of dispersed particles and porosity in the reservoir during colmatation, showing that over time the colmatation front propagates at a constant rate. It is shown that the colmatation coefficient is a small parameter that significantly determines the nature of oil displacement by water, and a decrease in the colmatation coefficient leads to a decrease in the rate of colmatation and the appearance and growth of the size of the stabilized zone near the displacement front.
7-18
Complex assessment of ambient particulate matter in a small settlement with coal-handling port
Abstract
Relevance. Russian coal exports have been steadily increasing in recent years, and Far Eastern ports, originally not adapted to dusty cargoes, have switched to coal operations. Unoptimized coal handling leads to increased content of coal-containing particles in the air and to various environmental problems.
Aim. To analyze the concentration of particulate matter in the air and the chemical composition of particles on the surface of conifer needles in the Posyet settlement (Primorsky Krai, Russia), where a large coal terminal operates.
Materials and methods. The chemical composition was studied on the surface of conifer needles by X-ray fluorescence and in washout of conifer needle samples using Raman spectroscopy and energy dispersive analysis. Concentrations of particles with the diameter of 2.5 and 10 μm (PM2.5 and PM10, respectively) were measured using automatic monitoring stations.
Results and conclusions. Chemical composition was dominated by mineral particles (calcite, silicates, etc.). However, the presence of coal particles (up to 8.3%) and metal particles was also observed. Mean concentrations of PM2.5 and PM10 were within the Russian and international health standards, but close to their upper limits. Concentrations of both measured particle fractions were highest during the winter months (as well as in March, which is traditionally a cold month in the Far East), followed by a gradual decrease. The study obtained new data on the annual variations of concentrations of PM2.5 and PM10, as well as on the basic composition of particles from the surface of woody vegetation (needles) as an indicator of the state of air pollution in this settlement.
19-31
Impact of boiler unit load changes on furnace processes
Abstract
Relevance. The need to assess the stability of combustion, thermal stress and nitrogen oxides (NOx) emission during load reduction of a steam boiler. Since renewable energy sources and nuclear power plants will receive great attention in the future, coal-fired thermal power plants are to operate at reduced loads, so it is important to investigate the reliability of operation and environmental parameters of the boiler unit in case of load adjustment.
Aim. To investigate pulverized coal fuel burnout, temperature parameters and NOx emission at 50% reduction of boiler unit load in the base configuration and taking into account installation of tertiary blast nozzles.
Objects. Furnace chamber of a natural circulation boiler unit with steam capacity of 220 t/h in the baseline layout and with tertiary air nozzles.
Methods. The package of application programs FIRE-3D for numerical study was applied. Combustion of pulverized coal fuel is a complex physical and chemical process, therefore the interaction of gas flow and solid particles was modeled using Eulerian and Lagrangian schemes, respectively. In the gas phase, the combustion of volatiles and CO with further combustion of carbon residue are modeled. NOx emission is modeled using post-treatment models including formation of fast, fuel and thermal nitrogen oxides.
Results. Temperature fields, flow characteristics, NOx emissions for different loads of the furnace chamber of the boiler unit with steam capacity of 220 t/hour are obtained on the basics of numerical modeling. The authors have obtained quantitative estimations of furnace environment parameters corresponding to several levels of boiler load reduction up to 50% of the nominal one. Installation of four tertiary blast nozzles allows reducing NOx emissions by 12.75% at theoretically required amount of air in burner devices (α=1.0).
32-42
Magnetic properties of lake Kandrykul sediments (Republic of Bashkortostan, Russian Federation)
Abstract
Relevance. It is known that sedimentary deposits in modern lakes with high sedimentation rates contain detailed paleoclimatic, paleobiological, paleoecological and magnetic records. The study of these parameters allow creation of paleoreconstructions and prediction of future climate behavior.
Aim. To identify ecological and climatic events and trends during the Late Quaternary, based on magnetic properties of rocks. Some climate-dependent parameters are not properly used, we are showing that magnetic parameters are sensitive indicators of climate change.
Object. Sediments of the Lake Kandrykul (Republic of Bashkortostan).
Materials and methods. A set of petromagnetic studies was carried out, including measurements of magnetic susceptibility, normal remanent magnetization in external magnetic field of up to 1.5 T, as well as differential thermomagnetic analysis on induced magnetization and scanning electron microscopy on selected samples. Normal magnetization curves were used to set apart dia-/paramagnetic, ferromagnetic and superparamagnetic components.
Results. Seismoacoustic studies showed that the lake bed is smooth, without sharp changes. The maximum water depth is about 16 m, the thickness of sediments reaches 7.5 m. Magnetic susceptibility was measured for three core columns, and the results show good correlation of this parameter between all the cores. Thermomagnetic analysis was used to determine magnetic minerals composition. The Day–Dunlop plot showed the presence of single, pseudo-single and multidomain grains. The authors determined the contribution of dia/para-, ferro-, and superparamagnetic components to the overall magnetic susceptibility. The paper considers the variations in magnetic susceptibility, para-, ferromagnetic components in the context of the Holocene climate changes.
Conclusions. Variations in magnetic properties reflect climate changes (i.e. deposition environment). Six zones with different depositional conditions were distinguished based on magnetic susceptibility and its component changes. Additionally, zones with single-domain particles were highlighted based on hysteresis parameters variations. These zones most likely are associated with the remains of magnetotactic bacteria. Joint analysis of paramagnetic, ferromagnetic susceptibility and hysteresis parameters produced information on the effect of total humidity on the bioproductivity of the lake.
43-55
Amazarkan gold deposit: conditions of formation, sources of ore substance (Eastern Transbaikalia)
Abstract
Relevance. The need to clarify the sources and conditions of formation of gold mineralisation of the Amarzakan gold deposit. The characteristic feature of the deposit is the spatial combination of gold mineralisation and small intrusions of the middle and basic composition of the Amudzhikan complex.
Aim. Determination of physico-chemical conditions and nature of the source of the ore substance of the Amazarkan deposit.
Methods. ICP-MS method and standard chemical analysis were used to determine the elemental composition of rocks. Sulfur isotope composition of sulfides was obtained using gas-source mass-spectrometry and fluid inclusions in quartz of ore veins were studied by traditional methods of thermobarogeochemistry and by FTIR spectroscopy at the Centre for Collective Use of Multi-element and Isotope Studies of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk). The oxygen isotope composition was determined at the Geological Institute of the Siberian Branch of the Russian Academy of Sciences (Ulan-Ude) using the MIR 10-30 laser heating system with a 100-watt CO2 laser and a wavelength of 10.6 µm in the infrared region in the presence of BrF5 reagent.
Results. The authors have established the spatial confinement of ore zones to Mesozoic dikes of the Amudzhikan complex (J2–3). The Eu/Sm and Eu/Eu* ratios in the dikes indicate fractionation of magmatic melts in the sources at the level of the lower continental crust and low degree of their differentiation. The character of REE distribution in the rocks of dikes of the Amudzhikan complex is similar to the distribution of REE in the ores of the deposit. Eu/Sm–Eu/Eu* figurative points of compositions of ore veins and granodiorites of the Amudzhikan complex form a single trend. Dykes of the Amuzhikan complex are characterized by increased Au content from 0.026 to 1.171 g/t. These data suggest a paragenetic link between Au mineralization and rocks of the Amudzhikan complex. Ore veins of productive stages of ore formation were formed at temperatures ranging from 125 to 410°C. The calculated S and O isotopic composition of the ore-forming fluid in equilibrium with pyrite and quartz, as well as the Co/Ni>1 ratio in the ores indicate the presence of a magmatic component in its composition.
56-70
Isotopic composition of natural waters of Kuzbass in coalbed methane production areas
Abstract
Relevance. In Kuzbass, a coalbed methane production project is being implemented for the first time in Russia. Formation water extracted together with coalbed methane plays an important role, since it has been in contact with the coal-bearing rocks for a long time, therefore it contains rich geochemical information. Over the period 2002–2022, new isotopic data were accumulated both on the waters of the region coal deposits and on overlying waters, including surface waters.
Aim. Based on the material accumulated on the isotopic composition (δD, δ18O, δ13C, 34S, 3H, 14C) of natural waters in coal-bearing areas, create an evolutionary scheme for the formation of waters within the framework of the developed hypothesis on the interaction of water-rock-coal-methane.
Objects. River, underground waters of the zone of active water exchange, upper and lower parts of the zone of slow water exchange (extracted together with coalbed methane).
Methods. Studies of the isotopic composition of waters were carried out in several laboratories: in the Multielement and Isotope Research Center of the SB RAS, the Technical Branch of the “SNIIGGIMS”, in the radiocarbon AMS laboratory based on the Center for Collective Use “Cenozoic Geochronology” and in the Pacific Oceanological Institute Far Eastern Branch Russian Academy of Sciences.
Results and conclusions. The paper introduces the data on δD, δ18О, δ13С и δ34S for surface and groundwater in Kuzbass in coalbed methane production areas. It is shown that all the waters under consideration are infiltration based on their isotopic composition (δD and δ18О). The waters of the lower part of the slow water exchange, produced together with coalbed methane, are characterized by a positive oxygen shift and very light hydrogen. A diagram of the evolution of the isotopic composition of water-dissolved carbon in the region has been compiled according to the data obtained. It is noted that the atmospheric source of CO2 is characteristic only of river waters, and only biogenic carbon dioxide is present in groundwater. The wide range of δ13СDIC values of the latter is explained by the varying degrees of participation of light soil carbon dioxide and heavy biochemical carbon dioxide formed during methane formation in the coal seam. The heaviest values are typical for waters produced together with coalbed methane, which is associated with long-term interaction with coal and methane. The time of such interaction was determined using the radiocarbon method: 17–30 thousand years. In areas where coalbed methane is produced, an increase in δ13СDIC values for all natural waters is observed, which requires further study.
71-86
Thermal engineering and chemical kinetics of wood pellets torrefication
Abstract
Relevance. The widespread distribution and availability of biomass in the regions of Russian Federation make it possible to consider it as a renewable energy source with a lower negative impact on the environment compared to fossil fuels, since biomass is recognized as a carbon-neutral fuel. The use of biomass as a fuel in the form of pellets is increasing, which provides increased density and heat value. At the same time, pellets as a fuel or as a technological raw material have a significant disadvantage – low hydrophobicity. This problem is solved by torrefaction – low-temperature pyrolysis at a temperature of 200–300°C to produce bio-carbon. The study of the wood pellets torrefaction in order to improve it is an urgent task.
Aim. To identify the impact of the parameters of the torrefaction of wood pellets on the thermal characteristics of the product (the highest heat value of bio-coal) and the regime parameters of the process (mass and energy yields), as well as to determine the parameters of the chemical kinetics of low-temperature pyrolysis as the basis for mathematical modeling and development of efficient torrefaction reactors.
Object. Torrefied coniferous wood pellets of domestic production (Moscow region).
Methods. Experimental study of the low-temperature pyrolysis thermal characteristics; synchronous thermal analysis in an inert atmosphere.
Results. It was found that during the torrefaction of wood pellets in an inert atmosphere, a change in the holding time in the range of 30–60 minutes does not significantly affect the higher heat value, mass and energy yield of bio-coal, while an increase in temperature from 250 to 300°C reduces mass and energy yield, and the higher heat value increases by 26%. The dynamics of mass loss and thermal effects when heated to 600°C at a rate of 10 K/min are determined by means of the synchronous thermal analysis. It is established that the chemical kinetics of the process is described by a generalized reaction of the order n=1.507, in the Arrhenius equation the activation energy E=71.25 kJ/mol, the pre-exponential factor A=4772 s–1.
87-100
Numerical simulation of the stress-strain state near the injection well at deep disposal facilities for liquid radioactive waste
Abstract
Relevance. The need to predict deformations of the earth's surface near injection wells pumping liquid radioactive waste, as well as their stability when pressure changes in the well during injection.
Aim. To perform a numerical analysis of the stress-strain state of the structural elements of the injection well and the surrounding rock mass using the finite element method, to determine the magnitude of the deformations of the earth's surface and define the stability of the well and the strength of the cement stone at the maximum injection pressure of liquid radioactive waste.
Objects. Near-wellbore zone of one of the injection wells located at the liquid radioactive waste injection site.
Methods. Numerical finite element method for calculating the stress-strain state of the near-wellbore zone, taking into account the distribution of the elastic properties of rocks along the simulated section and the main structural elements of the well.
Results. The authors have developed the numerical finite element scheme of one of the injection wells, taking into account its main structural elements, as well as allowing you to set the pressure distribution within the exploited horizon during the injection of waste. In the model, the distribution of the elastic properties of rocks along the section was set, taking into account their lithological features. The authors carried out the analysis of the hydrodynamic parameters of the well operation and determined the maximum pressure at the wellhead during the injection of liquid radioactive waste, equal to 1.71 MPa. Numerical modeling of the stress-strain state of the near-wellbore zone was performed in two stages: for the conditions of an idle well and taking into account the pressure distribution at the maximum waste injection pressure. The distribution of vertical displacements at the level of the earth's surface, as well as at the top of the operational horizon at the maximum pressure of liquid radioactive waste injection, is obtained. It is shown that at such a pressure, the largest uplifts will be: on the earth's surface – 4.5 cm, on the top of the production horizon – 11 cm. An assessment of the stability of the well structural elements at a maximum waste injection depth of 280 m, corresponding to the maximum pressure, showed that the stresses in the well and cement stone are much lower than the values that can lead to their violation. For cement stone, the safety factor at a maximum pressure of 1.71 MPa was equal to 7.8.
101-110
Device for preventing the formation of liquid plugs in a gas collection system or in a non-straight gas well
Abstract
Relevance. Almost all gas fields, both in Russia and in the world, are developed under water-pressure conditions, which means that sooner or later the field operator is faced with the problem of well watering and liquid accumulation at their bottom. The control methods proposed at this stage of development of science and technology and the useful models and inventions applied for this, although they show their effectiveness in removing droplet liquid from the production wellbore, do not contribute to the further advancement of the removed fluid through the system for collecting and preparing products. Because of this fact, a number of problems arise, for example, the formation of local resistance in the form of ice or hydrate plugs, the cause of which is the fluid removed from the wellbore.
Aim. Development of a universal device that can be used both in the production collection and preparation system and inside production wells, capable of injecting produced water into the gas flow in order to prevent the formation of “stagnant zones” of liquid.
Objects. Flooded gas wells, the gas pressure in which is not enough to remove droplet liquid from the wellbore or transport this liquid to the place of product preparation.
Methods. Assessment and analysis of existing devices to prevent the formation of liquid plugs in a gas collection system, identifying their main shortcomings, as well as mathematical modeling of the proposed model, in which these shortcomings are eliminated.
Results and conclusions. The paper introduces a brief description of the problem under study and studies and discusses the main methods of preventing the formation of liquid plugs, used in gas fields both in Russia and in other countries. The authors have proposed the design of a universal device, which is devoid of the main identified disadvantages of analogue devices, and carried out its simplified mathematical calculation.
111-119
Methods for determining scattered solar radiation in order to increase the accuracy of forecasting hourly electricity generation by solar power plants
Abstract
Relevance. А simple and up-to-date methodology is needed to assess the potential of electricity that can be obtained from solar power plants installed in different regions. The difficulty in assessing the potential of solar energy lies in the presence of some factors that affect electricity generation and depend on random events. Such factors include, first of all, the sky clarity, the direction of photovoltaic panels strictly to the Sun, dustiness, and ambient temperature. The literature uses different approaches to assess the potential of solar energy. This paper presents a methodology for evaluating the generation of electricity by a solar panel having a continuous solar tracking system, taking into account the dustiness and temperature of photovoltaic panels. The technique has been tested on an existing physical model.
Aim. To study the existing methods for assessing the potential of solar energy and to select the most suitable ones for the central part of Russia.
Object. Solar power plants.
Methods. Empirical and analytical methods. Using the data obtained from an operating solar station, the adequacy of the proposed methodology was assessed.
Results. The selected methods take into account the hourly sky clarity index, which made it possible, with sufficient accuracy for engineering techniques, to determine the daily power generation of a solar station with different angles of inclination of solar panels. This will improve the accuracy of estimating the potential of electricity generated by solar power plants, both with stationary photovoltaic panels and with solar tracking systems. Based on the conducted computational experiments and the analysis of data obtained from an operating solar station, the authors concluded that the technique presented in this paper allows us to determine with high enough accuracy the potential of electricity that can be produced in Russia by solar stations.
120-133
Integration of geoelectric methods and remote sensing in assessing the environment state in the area of impact of ecologically hazardous objects
Abstract
Relevance. The need for comprehensive assessment of environmental components in the zones of ecologically hazardous industrial facilities impact, which enables to operatively identify the spatial structure of technogenic pollution.
Aim. Chemical pollution assessment of the geological environment in the zones of industrial objects impact, based on the combined use of remote sensing and ground-based geoelectric methods.
Objects. Sources of pollution during the production of mineral fertilizers (phosphogypsum dumps, sulfur storage).
Methods. The author has developed a complex of methods, consisting of multispectral space imaging (Sentinel-2 satellite images) and ground-based geoelectric researches: water surface resistivity measurements, natural electric field potential imaging, vertical electrical sounding. According to satellite image data (vegetation indices NDVI, NBR, SWVI), technogenic geosystems modifications are distinguished, characterizing different levels of chemical pollution (TM-1, TM-2 and natural geosystem). Within the modification zones, geoelectrical studies are carried out to assess the depth of contamination.
Results. In the zone of phosphogypsum dumps impact, two technogenic modifications were distinguished, with a total area of 83.3 hectares, characterized by a statistically significant decrease in the values of vegetation indices compared to the average level. Based on the results of vertical electrical sounding, it was established that the depth of contamination in the TM-1 zone reaches up to 20 m, in the TM-2 zone – up to 2.5 m. The migration of contaminated substances from the dumps occurs with surface drain. In the zone of impact of the sulfur storage, the area of pollution, specified with vegetation indices, covers two hectares. According to the results of the natural electric field method and vertical electrical sounding, the flow of pollution from the sulfur storage site penetrates into groundwater, which is discharged in the TM-1 zone, causing the death of vegetation. In the TM-2 zone, contamination is registered only in the ground aquifer. The developed set of methods enables to quickly and relatively comprehensively diagnose the state of the undergoing technogenic impacts geological environment.
134-145
Progress on clay swelling inhibitors: a comprehensive review
Abstract
Relevance. It is known that swelling of a well wall due to the presence of water negatively affects drilling operations, causing a significant increase in their material costs. The use of various inhibitors prevents this effect and the drilling mud reacting on wellbore narrowing. In this sense, the problems of developing polymer, amino-, ionic liquid and shale inhibitors of surfactants considered in the article are very relevant and of practical interest to oil engineers in terms of the prospects for fundamental and applied researches of these issues.
Aim. To study the possibilities of existing approaches and methods that determine the characteristics of the main clay swelling inhibitors, the regularities of changes in the properties of traditional and non-traditional clay materials, as well as the mechanisms of clay swelling with the identification of the most characteristic group of these inhibitors.
Object. Processes of minimizing the effect of wall narrowing as a result of exposure to inhibitors.
Methods. Systematic, critical and comprehensive analysis of modern data on clay swelling inhibition in the field of drilling muds.
Results. The authors have carried out the detailed analysis of clay swelling. The paper discusses the characteristics of inhibitors required to prevent swelling, in the structure of which nitrogen and ionic liquids are contained. It is noted that a high-quality clay swelling inhibitor should include in its base a water-soluble bulk molecule with a distinct hydrophobic and hydrophilic structure; have characteristics, which allow replacing the hydrated cations of the intermediate layer with some hydrophobic cations, such as ammonium ions instead of sodium ions; differ in the ability to disperse multiple cations well. It was found that functional groups that support inhibitor binding to the siloxane groups of the clay are able to significantly expand clay swelling.
146-166
Negative impact of vibration on process pipelines of a compressor station with electrically driven gas pumping units
Abstract
Relevance. In gas industry, the amount of equipment that has outlived its intended service life is increasing every year. In accordance with the law “On Industrial Safety of Hazardous Production Facilities,” compressor stations are dangerous objects, the reliable operation of which largely determines the condition of main gas pipelines. Technological pipelines of a compressor station are important objects of this system. They are subject to strict requirements due to the action of static and dynamic loads on them. Reliability of compressor stations is based on the results of a study of the condition of the object and the main factors affecting increased wear of equipment. The solution to wear problem is timely monitoring of equipment, in particular level measurement and determining the causes of pipeline vibrations using vibration diagnostics methods, and frequency and modal analysis methods.
Aim. To study the causes of increased dynamic loads on the technological piping that arise during the operation of electric and gas pumping units at a compressor station using vibration monitoring methods.
Methods. Vibration monitoring methods to analyze the causes of increased vibration values in the process piping of a compressor station with an electric gas pumping unit.
Results and conclusions. The authors have measured vibration in a wide frequency band and assessed the technological condition of the main equipment of the compressor station with EGPA-6.3/8200-56/1.44-R based on the regulatory documentation STO Gazprom 2-2.3-324-2009. The main frequencies of the root-mean-square value of the vibration velocity, at which the highest vibration values were observed, were identified, and a modal analysis was performed using ANSYS software. Based on the results of natural studies and modal analysis, it was concluded about the occurrence of resonant high-frequency oscillations, multiple of the rotor rotation frequency.
167-177
Block method of mining quarry fields as a tool to reduce environmental impact in conditions of intensification of production
Abstract
Relevance. The intensification of open-pit mining in the coal basins of the Russian Federation is accompanied by an increase in negative impact on the environment. Directly in Kuzbass, the environment is exposed to the impact of the coal industry, especially when conducting open-pit mining using deep mining systems, with external dumping, which is accompanied by the withdrawal of a large amount of undisturbed land. The block method of mining quarry fields, well known in mining, has been rarely implemented in existing and planned quarry fields. The general line of its application is the lack of a unified approach to the design of block parameters, including environmental and economic assessment of the impact of this technological solution on the environment.
Aim. Reduce environmental payments of mining enterprises with justified parameters of blocks for the development of quarry fields of promising inclined and steeply dipping coal deposits.
Methods. Systematic generalization of the actual situation of mining operations in open-pit mines using the block method of mining quarry fields, the method of options and technical and economic modeling using spreadsheets.
Results and conclusions. The authors have proposed the ecological and economic criteria for assessing the application of the block method of quarry field development. This allows us to study the patterns of change in environmental indicators. Using the example of the Krasnobrodskoe open-pit mine, the costs of environmental payments for the use of land resources, emissions and dusting are calculated for two options different from the design documentation. Based on the calculation results, the authors proved the efficiency of applying the block procedure for developing promising coal deposits, allowing us to reduce the costs for environmental impact by 22.5 and 63%, respectively, when changing the length of the initial block along the bottom from 2.2 to 1.4 km. From which it follows that the combined ecological and economic indicators allow us to fully assess the feasibility of applying the method for calculating block parameters, which is generally reflected in reduction in the costs for negative impact on the environment.
178-188
Determination of geochemical stability of swamp ecosystems of the taiga zone of Western Siberia to anthropogenic impact
Abstract
Relevance. The need for scientifically based regulation of impacts on wetland ecosystems taking into account their specificity and geochemical stability.
Aim. To determine the geochemical stability of wetlands in the taiga zone of Western Siberia to pollutants for two typical cases associated with: 1) operation of sludge pits; 2) discharge of domestic and industrial wastewater.
Methods. Mathematical modeling, statistical methods.
Results and conclusions. The authors have carried out the analysis of the results of studies of the chemical composition of wetland waters and extracts from peat and mineral soils of wetlands in the taiga zone of Western Siberia (mainly in the Tomsk region, as well as in the adjacent territories of the Khanty-Mansiysk Autonomous Okrug, Novosibirsk and Omsk regions). They obtained the estimates of the average values of geochemical indicators of wetland waters and peat by the depth of the peat deposit in peat bogs with varying degrees of anthropogenic impact. The paper introduces the method for assessing the anthropogenic impact of wastewater discharge and geomigration on swamps in areas where oil and gas facilities are located (permissible concentrations in wastewater entering swamp ecosystems), taking into account the «geochemical background» and sorption capacity of peat. In particular, the authors substantiated and tested the method for assessing the values of permissible concentrations, which should be considered as a «relatively safe» level of impact on swamp ecosystems, at which secondary pollution of swamp waters is not expected. It is shown that anthropogenic changes are mainly limited vertically by the upper layer of the peat deposit up to 1–2 m, and horizontally (within the active horizon of the peat deposit) – by areas up to 100–200 m.
189-202
Uranium in groundwaters of North Kazakhstan
Abstract
Relevance. The need to dentify the characteristics of the distribution of radioactive elements in the groundwater of Northern Kazakhstan.
Aim. Generalization of available data on the geochemistry of groundwater and uranium and radon distribution in them using the example of the northern regions of the Republic of Kazakhstan.
Methods. Generalization of long-term hydrogeochemical research and compilation of an electronic data bank on the territory of Northern Kazakhstan. A laboratory study of the chemical composition of groundwater was carried out at the Research Laboratory of Hydrogeochemistry of the School of Natural Resources Engineering of Tomsk Polytechnic University. Measurements of 222Rn contents in waters were carried out using the Alfarad Plus complex in the Laboratory of Hydrogeology of Sedimentary Basins of Siberia, Institute of Geology and Geography, Siberian Branch, Russian Academy of Sciences.
Results. The groundwater of aquifers of different ages, distributed in the territory of Northern Kazakhstan (North Kazakhstan uranium province), was studied. Two geochemical sets of groundwater were identified. The first is characterized by the dominance of HCO3– and Mg2+ in the water composition, and the second by Cl– and Na+. A change in composition and an increase in the value of total mineralization from 0,1 to 49 g/dm3, in the direction from north to south, indicate the development of continental salinization. In natural waters of the first group, uranium content varies from 0.065 to 16000 μg/dm3 and radon activity from 4 to 3885 Bq/dm3. For sodium chloride waters of the second set, concentrations can reach 32500 μg/dm3, and radon activity is 6–59 Bq/dm3, since the emanating reservoir (granitoids) is located to the north – at a distance of 80–100 km. Naturally, granitoid massifs of the studied region are sources of uranium. Their drainage by the river network leads to its removal and concentration on geochemical barriers in the groundwater of the Neogene-Quaternary aquifer. This distribution of radioactive elements is associated with the high migration ability of uranium in solution in the form of uranyl ion in oxidizing geochemical conditions.
203-215
Polyaromatic hydrocarbons of small reservoirs of the Tomsk region
Abstract
Relevance. The assessment of the state of natural waters includes the determination of a number of physico-chemical indicators, on the basis of which various indices and classifications are developed. However, they do not take into account a number of pollutants that have a significant impact on the state of the reservoir, for example, polyaromatic hydrocarbons. The article considers some aspects of determining priority pollutants, which include polyaromatic hydrocarbons, according to environmental hazard criteria: toxicity, carcinogenicity, prevalence, frequency of occurrence, source of origin (anthropogenic or natural). Hydrochemical parameters such as pH, dissolved oxygen content, biological oxygen consumption (BPK5), and ion content are taken into account to determine water quality. An attempt was made to assess the impact of polyaromatic hydrocarbons on the ecological state of water bodies and to take into account their contribution to changes in the values of the water pollution index. All these data prove the relevance of the study.
Aim. To establish the composition of polyaromatic hydrocarbons in the surface waters of small reservoirs of the Tomsk region to assess anthropogenic load and to show the relationship with the indices of natural water quality.
Methods. Extraction, liquid adsorption chromatography, high-performance liquid chromatography, capillary electrophoresis, amperometry, titrimetry.
Results. Small lakes of the Tomsk region were studied for the content of 13 polyaromatic hydrocarbons. The authors have carried out the identification by high-performance liquid chromatography with fluorimetric detection. The total content of polyaromatic compounds in the studied surface water samples varies from 0.37 to 0.54 mcg/l. In the polyaromatic hydrocarbons mixture in aqueous samples, there is an increased content of light 2–3 nuclear polyarenes with better solubility (naphthalene, fluorene and phenanthrene), as well as benz[a]anthracene. The content of inorganic components represented by cations and anions does not exceed the maximum permissible concentrations. The water pollution index was calculated; all lakes are moderately polluted, closer to polluted. The paper demonstrates the dependence of the water pollution index coefficient on the content of high-molecular polyaromatic hydrocarbons and the ratio of high-molecular to low-molecular polyaromatic hydrocarbons. It is shown that the higher the value of the water pollution index coefficient, the higher the proportion of difficult-to-oxidize components in surface waters.
216-225
Experimental comparison of closed cooling systems of photovoltaic modules
Abstract
Relevance. The need to increase the efficiency of solar modules to 15–20% by cooling their surface, which in spring and summer is able to heat up to 70℃. Heat collection from photovoltaic modules is an additional opportunity to accumulate heat and use it for their own needs, especially for isolated power systems. The article discusses methods of closed cooling using tubes made of copper, metal plastic and stainless steel. All measurements were carried out in summer at a real, operating solar power plant located in the Crimea village of Karyernoe.
Aim. To experimentally determine and identify the effect of the most efficient cooling system for photovoltaic modules.
Methods. Methods of empirical research. In the experiment, sensors connected to the Arduino UNO system were used to measure the temperature and humidity of the ambient air, the temperature of the refrigerant at the inlet and outlet, and the data were recorded in an Excel table. Soudal FIX ALL adhesive sealant is used to fix the cooling system.
Results and conclusions. The authors have obtained volt-ampere characteristics, refrigerant inlet and outlet temperatures, photovoltaic modules surface temperatures. The cooling system made of stainless steel pipes showed the greatest cooling efficiency of the solar module, which allowed reducing the module temperature from 66 to 38℃ at some points. This increased the efficiency of photoelectric module by 3.5% relative to the rated power. The heated liquid from the photoelectric module has cooled down to its original temperature values, thanks to the installed cooling radiator, for the possibility of reuse of the liquid in the solar panel cooling circuit.
226-237
Identification of conditions for ultrasonic effect on gas-dispersed medium and creation of radiators to increase the efficiency of coagulation in devices with swirling flow
Abstract
Relevance. The presence and uncontrolled distribution of aerosols of various substances in the air, which have a negative impact on humans, flora and fauna. This problem is especially acute in the extraction, processing and combustion of georesources. The most effective way to solve the problem is the use of high-intensity ultrasonic vibrations, the effect of which on aerosols causes convergence and agglomeration of small particles into large ones. However, at low concentrations, the particle coagulation efficiency is not sufficient to increase the recovery rate of gas treatment equipment. Therefore, there is a need to find new ways to optimize ultrasonic equipment for coagulation of fine particles in order to increase its efficiency.
Aim. To determine the optimal conditions for ultrasonic influence on a swirling gas-dispersed flow, ensuring maximum efficiency of agglomeration of highly dispersed particles. Carrying out comparative studies of coagulation of particles when exposed to ultrasonic fields generated by different types of radiators and their combined effects will make it possible to determine the effectiveness of ultrasonic coagulation and the optimal design scheme of ultrasonic exposure.
Objects. Coagulation of particles under ultrasonic impact, formed by various types of radiators.
Methods. Computer modeling of the generated ultrasonic field using the finite element method with the help of harmonic acoustic analysis. Finite element modeling and design of disk radiators using modal analysis. To determine the characteristics of the aerosol, a Malvern Spraytec Particle Analyzer was used.
Results. The results of calculations and experiments have shown that the use of an extended ultrasonic tubular radiator operating on a bending-diametric mode of vibration and forming a ring standing wave with a sound pressure level of 162–165 dB as the main source of ultrasonic impact for devices with swirling flows may be the most energy efficient. Further increase in the efficiency of coagulation can only be achieved by the combined action of a tubular radiator and a longitudinally oscillating radiator. This significantly modifies the field structure and provides not only an increase in the sound pressure level (up to 167 dB), but also in the number of formed nodal surfaces (up to 44).
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Probabilistic reliability model of electrical motors in submersible well pumping units used in the uranium mining by in-situ leaching
Abstract
Relevance. A submersible electric motor is the most vulnerable component of an electric centrifugal pumping unit used in in-situ leaching uranium mining. The accuracy of calculating the need for new electric motors directly affects the profitability of the uranium production.
Aim. Development of a probabilistic reliability model for a submersible electric motor that provides the calculation of its failure probability for the upcoming period of time and allows estimating with sufficient accuracy the number of motors required to replace the failed ones.
Methods. Statistical methods, survival analysis, statistical hypothesis testing.
Results and conclusions. The authors conducted a study of three probabilistic reliability models for electric motors of submersible well pumping units used in in-situ leaching uranium mining. As a result of the study, the maximum likelihood estimates of model parameters were determined for each model; the adequacy of the models under study was checked based on nonparametric goodness-of-fit tests. Despite the fact that the test results did not allow excluding any of the considered models, a model based on a mixture of two Weibull distributions was selected as a probabilistic reliability model demonstrating higher consistency with real data, compared to the other models. At the same time, the analysis of the components of the mixture distribution indicated the presence of a group of electric motors with an uncharacteristically low time-to-failure value compared to the average value calculated for the entire set of equipment under study, and made it possible to estimate the share of such motors, which amounted to 8% of the total population. Possible reasons explaining such heterogeneity of data, according to the authors, are hidden manufacturing defects or more severe operating conditions in which some submersible electric motors operate.
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