The article is a continuation of a series of studies dedicated to the analysis of power transmission through distribution electric networks of PJSC ROSSETI. The presented material analyzes the functioning of the electrical networks of the branch of PJSC Rosseti Volga – Saratov Distribution Networks. An analytical assessment of the electric energy transport through distribution electric networks was carried out for the period 2018–2022. The structure of the company is considered, the structural characteristics of the main elements of the studied electrical networks are given, and the number of emergencies that occurred during the study period is estimated. A quantitative assessment of the magnitude of the electric energy undersupply caused by power supply interruptions is given. The classification of failures according to the degree of the intensity of undersupply was carried out and a quantitative assessment of each group of failures according to their intensity was made. The influence of the seasonal component on the number of emergencies during the study period is considered. Based on the data from 2022–2023, the analysis of the main causes of damage to the elements of electrical networks was carried out. The classification of failures by groups of failure causes is made, their main characteristics for this period are considered. The percentage ratio of the number of failures number for the most characteristic reasons to the total number of outages during the study period has been established. The information published in the open press was used as the source data. General scientific methods as well as numerical methods of analysis were used in the research. MATLAB graphics editor technologies were used to visualize the obtained analysis results. The results obtained may be of interest to the managers of power grid companies, as well as researchers and engineers engaged in research in the field of reliability of power supply. 

The article discusses issues related to improving the methodological foundations for analyzing the system reliability of electric power systems. In particular, a decomposition of the complex property “system reliability” is presented, which covers all stages of control of electric power systems. In accordance with the new decomposition, system reliability is formed by three components: security (operational reliability), planned reliability and adequacy. Each of the components is designed to solve specific problems at various stages of managing electrical power systems. Thus, the methodological apparatus for analyzing adequacy should mainly be used when solving problems of designing the development of electric power systems, the methodological apparatus for analyzing planned reliability should be used when solving problems of work planning (states and balances), and the methodological apparatus for analyzing security when solving problems of operational management. Unlike the concepts of adequacy and security, the concept of planned reliability is new. The article presents the rationale for introducing the concept of “planned reliability” into the practice of managing electric power systems. The main differences between planned reliability and security and adequacy are reflected. The basic requirements for the methodology for assessing the planned reliability of electric power systems are formulated. It is indicated that when assessing the planned reliability of electric power systems, it is necessary to take into account a number of random processes in the functioning of energy facilities, such as energy storage systems, hydroelectric power plants, renewable energy sources and others, and this requires the use of the mathematical apparatus of random processes in the functioning of systems. To assess planned reliability, it is proposed to use the sequential Monte Carlo method. 

At present, when energy prices are unstable and periodically rise, enhancing the energy efficiency of thermal power plants, which implies the production of the same or larger amounts of energy with a lower consumption of energy resources, remains an urgent problem in the field of thermal power engineering. Such tasks aimed at reducing the consumption of energy resources for their own needs are quite urgent for manufacturing enterprises that use energyconsuming equipment, in particular steam boiler plants. Steam boiler houses contain a sufficient amount of energyintensive equipment, be it the boilers themselves or atmospheric deaerators, which are used to purify the boiler feedwater from corrosive gases. The article discusses the option of automating the process of closing the vapor during atmospheric deaeration in boiler plants by installing valves with automatic drives on the vapor removal pipelines. The article also analyzes the annual replenishment flow rate of the deaerator, assesses the quality of the condensate supplied to the deaerator, describes the conditions for opening and closing valves with automatic drives, and provides a calculation of the time delay required to remove vapor from the deaerator before closing the valves. A functional block diagram for controlling automatically driven valves is presented and its components are described. Thus, when implementing the described technology, significant savings in production steam spent on the deaerator will be achieved due to the closing of the deaerator vapor, with no chemically purified water supplied to the deaerator. This solution helps to increase the operating efficiency of the entire boiler installation. 

The air heaters used for heating blast furnace blast have recently undergone a number of design changes, which has affected their key thermal performance indicators. There are established temperatures at which settled operating conditions show sufficient technical and economic performance. Deviation from the conditions by increasing the temperature of the hot blast entails negative consequences of a different nature, which ultimately makes it unfeasible from an economic point of view. New design solutions for air heaters must be determined by maximum temperatures, which affects the service life of the equipment and system. Consequently, the development of the heat transfer surface of the nozzle plays an important role in solving the problem. Increasing the reliability of the apparatus and achieving high thermal performance indicators will result from improving the design of regenerative devices. By applying a mathematical model to the calculation of flows in a system of channels of an arbitrary given structure, calculations of coolant flows through the channels of a blast furnace heater nozzle were obtained. Modeling of flow non-uniformity at the inlet to the nozzle was carried out for different pressure fields at the inlet to the nozzle with horizontal channels. The results of the specified pressure fields at the entrance to the system and the results of calculating the mass flow rates of the coolant through vertical and horizontal channels are presented. It has been confirmed that the pattern of the pressure field at the inlet to the nozzle and the velocity field in the supply vertical channels are different due to the mutual influence of adjacent vertical channels because of their being connected into a single system by horizontal channels. Calculations have confirmed that horizontal channels do not actively participate in the heat exchange process. For better efficiency, it was proposed to make horizontal channels not along the entire height of the nozzle, but only in its upper and lower layers. 

Unfortunately, in a growing number of publications of the results of the study of turbomachines in ANSYS and other packages, insufficient attention is paid to the choice of the flow model (absolute or relative) and the setting of boundary conditions in the areas adjacent to the rotating impeller: shroud seal, diaphragm (end) seals, gap over shroudless blades, steam balance holes, etc.

As a rule, these areas contain such elements of geometry as a “ledge”, “projection”, “crest”, the flow around which, and, consequently, their resistance depends on the angle of incoming flow relative to the barrier. In the stages of turbomachines in sections behind fixed blade units, angle α1 between the flow velocity vector (in absolute motion) and the circumferential velocity is 10°÷25° (for steam turbine stages), 20°÷35° (for gas turbine stages) and 40°÷75° ((for axial compressor stages). It is shown (using the example of viscous flow around the “ledge + projection” system) that a change in the angle in the range of 15°÷90° changes the resistance by almost 2 times.

The choice of a particular type of flow model (absolute or relative) for the domain primarily determines the value of the angle of interaction of the flow lines with an obstacle: it remains close to α1, or close to β1 = α1 + 20°÷70°, which significantly changes the qualitative picture of the viscous flow around the characteristic elements of geometry (“ledge”, “projection”, “crest”), and the values of integral parameters (flow rate, power, efficiency). The lack of recommendations on the correct choice of boundary conditions will inevitably lead not only to the inability to compare the results of various published studies, but also to their objective value. Therefore, the need to substantiate proposals for the choice of flow models in the areas of labyrinth seals, steam balance holes, gaps over shroudless blades, etc. is very relevant. 

Hydraulic tests are used in various sectors of the national economy to check the strength and tightness of vessels and pipelines, their parts and assembly units loaded with pressure. The hydraulic test pressure is a calculated value and is determined on the basis of regulatory documentation for the relevant control objects. Analysis of current trends in the field of hydraulic testing both in the Russian Federation and abroad has shown a trend to reduce the damageability of test objects by choosing the most optimal hydraulic test pressure. The main purpose of the research was to reduce the operational damage to equipment and pipelines of nuclear power plants by reducing the pressure of hydraulic strength tests during maintenance. The research is based on probability theory, mathematical statistics, strength physics and fracture mechanics, taking into account the possibility of occasional discontinuities or defects that might be observed in operation. The method is based on a risk-based approach, which makes it possible to determine the permissible risk variation based on recommendations on the safety of nuclear power plants in the Russian Federation. The objects of research are the equipment and pipelines of nuclear power plants. The result of the research is the development of a method substantiating the reduction of the pressure of hydraulic strength tests for equipment and pipelines of nuclear power plants based on a risk-based approach. The developed method can be used by organizations involved in the production of electricity (at nuclear or thermal power plants), transportation of oil, gas or other substances, at facilities where pipelines are an essential part of their structures, affecting the reliability and efficiency of operation of these facilities. 

This article considers a 500 kW closed cycle gas turbine unit. In contrast to open or semi-closed cycles, a closed cycle implies a working fluid circulating continuously within a closed loop. In other words, a working fluid (any working fluid) with the required initial parameters depending on the properties of the selected working fluid is injected into a closed circuit consisting of a compressor, heat exchangers of various purposes and a turbine. A unit with recirculation of combustion products at high pressure can be created based on existing units with minor modifications. Instead of emission into the atmosphere, the exhaust gases enter the high-temperature heat exchanger, where it gives heat to the closed-cycle gas turbine unit. First of all, the application of such units is relevant at compressor stations in conjunction with the gas turbine drive of the blower. The study involved thermal calculation of a closed-cycle gas turbine unit with different working fluids: carbon dioxide, helium and argon. The main objective is to study the advantages and disadvantages of alternative working fluids with their subsequent comparison. Since the main chemical and physical properties of alternative working fluids differ from the classical ones, there is a possibility of obtaining higher parameters of the unit. According to the results of calculations it is established that the most promising working fluid is carbon dioxide, because this can be used at a wide range of temperatures and pressures. It should also be noted that the consumption of carbon dioxide is the lowest compared to other working fluids. The efficiency of such an installation is 28%, but there is a possibility of improvement if regeneration is added. 

Modern technologies and the continuous rise in water consumption require efficient and environmentally friendly methods of its extraction. According to the energy development strategy of the Russian Federation until 2035, the use of alternative energy sources in industry is a priority task for production. The use of renewable resources to produce distilled water for the needs of enterprises is becoming increasingly important. The innovative technology of a laboratory installation, combining water distillation using a heat pump and a photovoltaic panel, allows not only to obtain purified water, but also to heat the coolant before chemical purification. To create a laboratory stand, it is necessary to study the operating principles of the installation, divide the device into units: the main stand and the vacuum distiller, then model a three-dimensional image of each part of the complex in the SolidWorks software package. Based on the obtained models, a functional diagram of the complex is developed to obtain a coolant of the given parameters, and an algorithm is compiled for predicting the temperature of the heated water in the heat pump. The obtained installation test results are processed, and compared with theoretical data from tables of refrigerant properties, and a conclusion is drawn. The technology for producing purified water is aimed at replacing imported technologies and using renewable energy sources. The development of technologies for producing clean water is a priority for the development of the Russian energy sector. The results obtained indicate the potential of the laboratory installation for use in various areas where a reliable and environmentally friendly supply of distilled water is required, for example, in coastal areas for industrial facilities or agricultural enterprises. 

The technological process of low-temperature purification of fuel combustion products of boiler units from carbon dioxide by freezing it in a turboexpander and separating from the fuel combustion products flow in a separator is considered.

The issue of separation of solid carbon dioxide from the flow of fuel combustion products of boiler units using a bag filter, an electric precipitator, a cyclone separator and an inertia-type separator is considered. Based on the analysis, the use of an inertial vacuum separator for separating the solid phase of carbon dioxide from the flow of fuel combustion products is proposed.

Solidworks and ANSYS CFX modules were used for numerical modeling. To solve, the equations of continuity, motion, energy, and the k-ε model equations are used. The closing equation is for the effective and turbulent viscosity. There is also a description of the forces affecting the movement of the dispersed phase. The stream is considered lightly dusty.

Numerical studies of the dispersed flow in the channel of an inertial-vacuum separator and in the previously used cyclone TsN-11 were carried out. The initial data for the calculation were taken based on the known mass flow rate and particle concentration, as well as from the continuity equation. From the results obtained, we can draw conclusions about a directly proportional relationship between the growth of the flow rate characteristics of the flow, the speeds along the flow path of the apparatus at the inlet and the resistance of the apparatus.

Besides, based on the obtained calculation results, it was concluded that it is necessary to additionally install a rotary industrial air blower in order to create the necessary pressure drop in the inertial vacuum separator. The economic and environmental feasibility of installing a rotary air blower is considered

The range of consumption of fuel combustion products has been determined at which the most effective purification of fuel combustion products from carbon dioxide in an inertial vacuum separator is possible within the technical characteristics of the refrigeration capacity of turborefrigeration machines.