Improving the efficiency of gas pipeline cleaning by controlling the speed of the gas cleaning

An important aspect of improving the hydraulic efficiency of pipeline transport is its periodic cleaning with mechanical cleaning devices. Cleaning gas pipelines with cleaning pistons is a technologically complex process. It is advisable to adjust the speed of the piston to increase the efficiency of cleaning the pipeline with the crossed track profile. On the ascending and plain sections of the route, maintain a high speed of movement of the device, and on the descending it to reduce. To slow down the movement of the piston in the downstream sections of the main gas pipelines, it is proposed to change the technological scheme of the linear part. It is suggested to use a looping connection to change the flow chart. The change of the speed of movement of the treatment device when changing the technological scheme of the main gas pipeline was evaluated. The influence on the dynamics of the movement of the cleaning piston of the main parameters of the pipeline and looping, as well as the parameters of the movement of the piston itself, are investigated. A mathematical model of the process is built, on the basis of the implementation of which the regularities of the treatment device movement when changing the technological scheme of the gas pipeline are established. An equation was obtained to find the ratio of the mass flow rates of gas in the main gas pipeline before and after connecting the loop, which can be solved by the iteration method. The algorithm is developed and the program of calculation of the degree of reduction of the speed of movement of the piston is developed, depending on the kind of technological parameters and technical characteristics of the treatment device and the pipeline. Based on the calculations, the graphical dependences of the relative speed of the piston on the technological parameters and technical characteristics of the main pipeline were constructed. The authors found that the greatest effect on the degree of reduction of the speed of the piston has the length of the loop. It has been investigated that a decrease in the initial pressure and an increase in the final pressure, as well as an increase in the pressure drop at the moving boundary, lead to an improvement in the braking conditions

Improving the energy efficiency of a solar power plant

The urgency of the work is due to the feasibility of increasing the energy efficiency of solar power plants through the use of solar energy concentrators. Ways to improve the energy efficiency of solar panels using a sys-tem of directional mirrors, flat Fresnel lenses, spherical concentrators and trackers have been investigated. It is established that the most optimal way to improve the energy efficiency of solar panels is to use inexpensive track-ers with a simple design. The analysis of known types of solar panels, which differ in materials from which their elements are made, and the coefficients of efficiency – dependence of energy produced by a photocell on the intensity of solar radiation per unit of its surface has been carried out, and the type of solar panels by the criterion “price-quality” has been selected. A tracker design has been developed to track the angle of inclination of solar panels to increase efficiency. The electricity generated by the proposed solar power plant was calculated using an online calculator. It is projected to reduce losses when generating electricity for a given power plant due to the use of a tracker compared to a fixed power system, with the same number of solar panels. In order to reduce the cost of the tracker, it is suggested to orientate it to the south at once, and to change the inclination angles twice a year (in early April and late August). The energy efficiency of the power plant is calculated in two stages. At the first stage the amount of electricity from solar panels per year when adjusting only the angle of inclination of the panels to the south is calculated. At the second stage energy efficiency of the power plant is calculated taking into account the increase of energy efficiency of the solar power plant when using the tracker system. The calculated electricity generation of the proposed solar power plant with tracker confirmed the efficiency and feasibility of using the designed tracker system. The application of the designed tracker system allows to increase the energy efficiency of solar panels by an average of 25%.

Development of technology for repair of shaped elements of pipeline systems in hard-to-reach places

It is proposed that erosion or corrosion worn out bends of pipeline systems in hard-to-reach places be repaired by trenchless methods by pulling a sleeve or a flexible composite pipe with a piston. The possibility of implementing such an idea is confirmed by theoretical and experimental studies. Mathematical modeling of the process of pulling a sleeve by a piston by a pipeline that contains a defective tap is performed. Formulas are derived for determining all resistance forces acting on a mobile system, patterns of pressure changes at the compressor outlet during such work are determined. A technique has been developed for calculating the friction force between the sleeve and the inner wall of the pipeline at the outlet, due to the pressing of the sleeve through a change in the direction of pulling. The dependence of the required pressure for the piston to extend the sleeve only with a defective bend on the bend angle of the bend is determined. An experimental setup has been developed and built to study the dynamics of the sleeve pulling by a piston. As a result of the experimental tests, it was found that it is possible to extend the sleeve through a pipeline with a piston that contains bend. The resistance forces acting on the moving system, the patterns of pressure change at the beginning of the pipeline in time when the sleeve is pulled by the piston, are experimentally determined. The experimental results are compared with the results of theoretical calculations and the reliability of theoretically derived dependencies is confirmed. The technique and technology for repairing defective pipe bends in hard-to-reach places has been developed by pulling a sleeve or a flexible composite pipe with a piston. The piston moves under the pressure of the air supplied to the piston space by the compressor. A drum with a wound sleeve or flexible composite pipe is placed in a cylindrical sealed chamber. A special supporting device has been developed to place a flexible composite pipe wound into a bay in a cylindrical sealed chamber.

Analysis of residual gases of internal combustion engines at working on biogas and their effects on the environment

Given the limited resources of Ukraine in petroleum fuels for internal combustion engines, the use of alternative fuels is quite relevant. One of their sources is biogas from livestock by-products and garbage dump. Ukraine has significant volumes of these renewable sources, the potential of which reaches more than 100 million tons of conventional fuel. Unfortunately, this resource is rarely used. In developed countries, biogas is widely used for electricity generation in power plants with internal combustion engines. Today in the United States the volume of biogas production is about 500 million m3 / year, in France – 40 million m3 / year. In the Czech Republic, Austria, Denmark, Finland and other countries, biogas is used as a motor fuel. Business Concerns Volvo, Scania produce buses running on biogas. In Ukraine, gas from landfills and livestock by-products is mostly released into the atmosphere or burned by flares, polluting the surrounding air. This causes additional greenhouse gas emissions. It is known that the main source of air pollution is vehicles. Exhaust, i.e. residual gases are considered toxic. The World Motor Vehicle Park annually emits up to 260 million tons of carbon monoxide, 40 million tons of volatile hydrocarbons, nitrogen oxides and others. The composition of the residual gases of the internal combustion en-gine depends on the component composition of the sources of fuel and, of course, on the mode of operation of the internal combustion engine In the given article the structure of residual gases of internal combustion engines at work on biogas is analyzed and their influence on environment is generalized. Based on analytical calculations, it is determined how the amount of residual gas components changes depending on the excess air ratio and the per-centage of methane in biogas. Recommendations for improving the performance of internal combustion engines on biogas by using it in mixtures with natural gas are given. According to the research results, the corresponding graphical dependences are constructed.

Mathematical modeling in the problems of the geodesic control of the stressed-formated state of the gas pipelines at above-ground parts

Geodetic methods of monitoring the stress-strain state of gas pipelines in the areas of overhead pipeline crossing involve obtaining discrete data on the deformation of its axis in the form of a set of three coordinates (x, y, z). For their elaboration a mathematical model of the experimental-theoretical method of geodetic control of gas pipelines’ SSS is proposed. The simulation process was performed on the basis of geodetic discrete data, based on which, using the Lagrange interpolation polynomial, the equation of the line of bending of the axis of the gas pipeline was obtained, which allowed to pass further to the bending moments along the entire span. The accuracy of the proposed method has been estimated, which showed that the obtained bending moment diagrams reflect the SSS of gas pipelines with an accuracy of 1.5% in the central part of its span, and with the approach to the peripheral sections the error increases to 6%. It is shown that the obtained expression of the maximum bending moment allows us to form the required number of additional equations for the disclosure of a statically indeterminate system of "gas pipeline-support", taking into account the possibility of fastening on stretch marks. The mathematical model is presented aimed at decomposition of overburden gas pipeline structures, which allows to model the SSS at each of the spans separately within the integral structure.. It is established that additional stretch marks reduce the maximum bending stress by 22%, and in case of loss of one of the stretches of the bearing capacity of the gas pipeline SSS increases by 11.1-14.8% depending on the previous stretch tension. The proposed mathematical model for the processing of discrete data forms the basis of the experimental-theoretical method of geodetic control of the gas pipelines’ SSS, taking into account their structural and technological factors.

Investigation of parameters of mixing and heat formation of diesel engines in the process of using alternative fuels

Today in Ukraine and the world there is a growing shortage of commercial fuels for engines. This is due to the tendency to regulate the production of hydrocarbons, which is the main raw material for their production. Therefore, in order to reduce oil imports, alternative fuels for diesel engines based on oils and animal fats are be-coming more widespread today. In this regard, intensive work is underway to convert internal combustion engines to biofuels in countries with limited fuel and energy resources, as well as in highly developed countries that have the ability to purchase liquid energy. Biodiesel fuel (biodiesel, RME, RME, FAME, EMAG, etc.) is an environmentally friendly type of biofuel obtained from vegetable and animal fats and used to replace petroleum diesel fuel. In the process of using RME B100 biodiesel fuel on the Renault 2.5 DCI engine, the average diameter of the fuel droplets is increased and the flare opening angle is reduced. This leads to impaired fuel distribution in the areas of the spray torch. Only 50% of the fuel is in the jet shell, which leads to impaired mixing of fuel with air. In the core of the wall there is 18% of fuel, which will spread along the walls and mix poorly with air. The remaining 36% of the fuel will be in the core of the jet, the front of the free jet and the areas of intersection of the near-wall streams, and will partially participate in the mixing. The use of biodiesel fuel RME B100 leads to a delay of heat by 18-20 degrees of rotation of the crankshaft, which will increase fuel consumption and reduce engine power. Thus, according to studies of the Renault 2.5 DCI engine on commercial and biodiesel RME B100, it is established that the use of biodiesel leads to a deterioration of the mixture due to reduced heat and as a result increases fuel consumption, reducing engine power.

Special features of tight gas reserves determination

Special features of tight gas reserves determination, based on material balance method, were characterized, since reliability of initial hydrocarbons in place determination plays important role in future field development planning, particularly on recovery rate, wells to be drilled, capital expenditures, surface facilities etc. Using the synthetic 3D model of gas reservoir, different development scenarios were evaluated according to the different spatial distribution patterns of petrophysical properties within the reservoir. Analyzing the obtained results, the authors fully confirmed an assumption made, that significant heterogeneity of reservoir properties makes a great impact on the shape of pseudo reservoir pressure curve vs cumulative gas produced and introduces significant errors into determination of initial gas in place. At the late stages of the development, the slope of P/z straight line changes, and this allows determination of much greater reserves’ volumes. Usage of pseudo reservoir pressure vs cumulative produced gas for determination of drained reserves in tight gas formation is especially risky, because the production data can indicate the true volumes of gas in place, only after the majority of the gas been produced. In most cases, the development period to acquire necessary data for correct volumes in place estimation exceeds the planning period. This factor introduces the significant error into future field development during the planning phase. Due to that, at the initial development stages, the error in drained volumes estimation can account for 50% out of true initial volumes in place. Based on conducted research, the potential error evaluation for tight gas reservoirs initial gas in place determination with decline pressure material balance method was performed. According to the results of computer simulation, the error can account for 25% from true initial gas in place in simulation model. This error significantly excesses the acceptable limits and can lead to wrong decisions in development planning

Optimization of design and mode parameters of the well ejection system

Insufficient energy performance of ejection equipment and a high probability of non-operating modes of its operation reduce the efficiency of downhole jet pumps. The method of determining the design and operating parameters of the well ejection system, which provide the maximum efficiency of the jet pump, is presented. The proposed algorithm for determining the optimal values of the geometric dimensions of the flowing part of the jet pump involves the construction of a series of pressure characteristics for different values of its geometric parameter, the calculation of the efficiency and the determination of the injection ratio and the relative pressure corresponding to its maximum values. During the studies, the main geometric parameter of the jet pump varied in the range from 2 to 6, given that these geometric dimensions are used in jet devices common in the oil industry. The optimal dimensions of the current part of the jet pump are obtained in the process of studying its pressure characteristics, and the optimal dimensions of the washing system of the bit - in the process of studying the characteristics of the hydraulic system. The design of an at-bit ejection system, which allows to increase the mechanical drilling speed, the passage of the bit, to stabilize the moment on the bit, to reduce its level of vibration and to control the antiaircraft angles of the well is considered. The efficiency of using at-bit jet pumps is in the following: an increase in the mechanical drilling speed up to 18.7%, the passage of the bit up to 50.8%. The research established the optimal diameters of the working nozzle, mixing chamber and bit nozzles, the distance between the working nozzle and the mixing chamber, the injection ratio and the relative pressure of the at-bit jet pump. The obtained values ​​of design and mode parameters exclude the occurrence of cavitation modes of operation of the ejection system and allow the operation of jet pumps with maximum efficiency.

Динамічний скрут підземного трубопроводу від раптового повоpоту фрагмента основи

У цій статті ми вивчаємо питання міцності підземних трубопроводів, які прокладені через території тектонічних розломів, і, як наслідок, експлуатуються в складних гірничо-геологічних умовах. На таких небезпечних ділянках окрім штатного навантаження тиском транспортованого продукту труба зазнає додаткових впливів від рухів неоднорідної, часто пошкодженої основи. Прогнозовано найбільш небезпечною виглядає ситуація, коли такі рухи є швидкоплинними. Метою роботи є розробка моделі для описання нестаціонарного процесу деформування трубопроводу на пошкодженій основі, спричиненого раптовим взаємним розворотом блоків довкола осі труби. Динаміку трубопроводу досліджували в лінійній постановці, моделюючи його стрижнем з трубчастим поперечним перерізом. При розгляді питань граничної рівноваги долучали безмоментну теорію циліндричних оболонок та енергетичну концепцію міцності. ґрунтову засипку розглядали як пружний прошарок Вінклера. Локальне порушеннями суцільності жорсткої основи описується раптовим розривом кута повороту її фрагмента. Такий підхід, відпрацьований на задачах статики, дає можливість і в динаміці оцінювати міцність підземного трубопроводу не за зовнішнім навантаженням від ґрунту, яке зазвичай є невідомим, а за спостережуваними чи прогнозованими параметрами рухів берегів розлому. Сформулювали початково-крайову задачу для гіперболічного диференціального рівняння скруту з розривною правою частиною. На підставі аналітичного розв’язку задачі, побудованого у вигляді квадратур від функцій Бесселя, вивчено вплив раптового розвороту фрагмента основи довкола осі труби на напружено-деформований стан трубопроводу. Побудовано графіки просторово-часового розподілу кута повороту, кутової швидкості, крутної деформації та еквівалентного напруження Мізеса в передфронтовій та післяфронтовій області. Встановлено, що урахування динамічних ефектів призводить до підвищення максимумів деформації скруту та еквівалентного напруження у стінці труби порівняно з випадком статичного збурення.

Analysis of wave disturbance in the drill string while releasing stuck pipes

The work is devoted to testing the hypothesis about the possibility of assessing the nature of the release of the drilling tool by percussion devices by analyzing the response of the system in the form of vibration records of the upper end of the drilling tool. For this purpose, based on the examined existing theoretical models, a wave diagram of the propagation, reflection and interference of deformation waves caused by the operation of the percussion device along the tacked drilling tool is constructed. Based on the developed diagram, a prediction is made of the nature of the oscillatory processes of the upper end of the drilling tool of a typical design located in a vertical well and the nature of their occurrence is explained. Based on the presented theoretical model the authors made an analysis of records in relative units of the vibration velocity of the upper end of a drilling tool in two specific cases of freeing stuck drilling tools in wells No. 812-Pasichna and No. 903-Pasichna of Nadvirna and Ivano-Frankivsk UBR, where they used VUK-170 that worked in jar mode. For this purpose, the time-frequency representation of the obtained records in the form of spectrogram, scalogram and Wigner-Ville pseudo-distribution was performed, and, based on the obtained theoretical prediction of oscillations of the upper end of the drilling tool, the time of the following stages of the percussion cycle – striking, impact and post – was established. Based on the data obtained, a time-frequency impact assessment was carried out and the character of the attenuation of deformation waves in the drill string was evaluated. Based on the well-known arrangement of stuck drilling tools, the propagation speed of deformation waves along the drill string is determined, which turned out to be more than theoretically calculated for an ideal thin rod according to the wave equation. The paper considers further directions of development of the proposed approach, as well as the use of its results to increase the efficiency of the freeing of stuck tool using impact tools.