Hydrogen energy combines a set of technologies for the production, transportation, storage and use of a versatile secondary energy carrier — hydrogen. The energy use of hydrogen is formed from the possibilities of environmentfriendly generation of electricity and long-term storage without loss, including on a large scale. Questions related to the consumption of hydrogen as a promising environment-friendly and versatile energy carrier and energy storage in various sectors of the national economy were formulated in the early 70s of the last century after the first oil fuel crisis. It has become obvious that it is necessary to develop new, ecologically optimal energy technologies based on the use of renewable energy sources, nuclear energy, coal and versatile environment-friendly energy carriers, making it possible to replace non-renewable energy resources as these are depleted and become more expensive. Hydrogen as a secondary energy carrier reveals its potential in a global strategy for sustainable energy development in the 21st century, which confronts the challenges of irreversible climate change, unsustainable oil production and increasing environmental pollution. Hydrogen can play a key role in mainline transportation by road and rail, in coastal and international shipping, in air transport, as well as in long-term and seasonal storage of electricity in networks, relying mainly on local renewable energy sources and local raw materials. The decisive element in the commercialization of hydrogen fuel technologies in Russia at the current stage is the formation of cost-effective hydrogen-transport-energy complexes, in particular, within power generating facilities.

To solve the problem of further improving the efficiency and reliability of solid fuel generation in the Russian Federation, it is necessary to solve a number of main problems: ensuring environmental safety, export-oriented nature of the coal industry, low reliability, efficiency, high emissions of NOx , SO2 and particulate matter of existing obsolete equipment. In modern conditions, these problems can be solved comprehensively with the use of relatively low-cost methods in the case of using highly reactive coals, which at the same time have an increased explosion hazard (coals of explosiveness groups 3 and 4). For this reason, currently a large number of coal-fired power plants (mainly in Siberia and the Urals) experience a global transition to the combustion of highly explosive Kuznetsk coal of grades D, G, GD. In the present work, analysis is undertaken of methods and technologies to ensure the explosion and fire safety of fuel preparation systems for combustion at thermal power plants during the transition to these types of fuels, since most of these thermal power plants were initially designed for explosion-proof types of coal (T, 1CC, AH). A number of additional recommendations are developed to the current "rules of explosion safety", taking into account the specifics of technological schemes and the operation of a large number of these thermal power plants, a number of design solutions for equipment that improve the explosion safety of their dust treatment plants. For systems of preparation of finely crushed fuel (5–15 mm), boilers with circulating fluidized bed that are promising for the Russian power industry, and the use of drying installations at thermal power plants to ensure crushing of ordinary high-humidity fuels entering thermal power plants, a number of measures have been proposed that increase the fire safety of such installations.

Heat carrier transportation in district heating (DH) systems is an issue of a significant energy saving potential. This potential can be achieved by applying a thermohydraulic dispatcher (THD) into DH systems. THD is a vertical or horizontal shunt pipe of a large diameter with relatively low hydraulic resistance in comparison with that of connected circuits. Installation of THD along with distributed variable speed pumps in DH systems can lead to reducing or even eliminating electric energy losses caused by throttling of redundant hydraulic head. It also leads to decreasing pressure in heat supply network which improves reliability of the network. But the opportunity of further rational implementation of THD in DH systems is limited because of insufficient amount of theoretical and experimental research. This paper is concerned with the experimental research of THD operating regimes. Already known aspects of THD operation were checked and proved. New dependencies were obtained for bypassing regime and for mixing regime of THD. Besides, different types of the primary circuit connection to THD were considered: connection for non-condensing boilers and connection for condensing boilers. Simplified models describing bypassing and mixing regimes of THD were proposed. It is possible to estimate return temperature of primary circuit with the help of the bypassing regime model with an error less than 1%. At the same time the mixing regime model is suitable for finding supply temperatures of primary circuits with an error less than 2%.

The results of this paper can be used for further research and development of DH systems with THD. Such systems could be traditional as well as prospective ones (low temperature and pressure DH systems). 

For the first time in the practice of full-scale studies in the area of the Chirkei HPP dam, the method of dipole electric sounding was used. The aim was to study the geodynamic processes in the rock mass located in the sides of the highrise dam to develop new methods of control of natural and man-made hazardous geological processes. The basis for the study of deformation processes in a large volume of the right bank of the dam was laid by the results of electric sounding of rocks by a small four-electrode in-well installation over the period 2010–2015, which showed that the change in the level of the reservoir caused seasonal deformation of rocks. The use of dipole sounding can significantly increase the size of the object under study. The volume of the probed rocks of the right bank of the dam is 6×106 m3, that is 2000 times larger compared to the four-electrode in-well installation. The equipment used is characterized by the continuity and high accuracy of measurements of apparent resistance of the mass, which enables to register the dynamic processes occurring in it. The results of observations by the method of dipole sounding over a short period of 2018 enable to conclude about the anthropogenic impact of the Chirkei hydroelectric power plant on the stress-strain state of rocks adjacent to the right side of the dam. For individual periods of observation, variations of apparent resistivity of large amplitude are detected, suggesting that the analyzed mass is in conditions of unstable equilibrium, i. e. displacements occur from time to time along the cracks in place. The movements can be triggered by starts of hydraulic units. Shifts in large tectonic cracks in the rock mass near the right side of the dam can lead to landslide processes and opening of cracks in the dam contact zone. The method of continuous dipole electric sounding can find its practical application for monitoring of hazardous geological processes in hydroelectric power plants.

A modified scheme of heat supply of residential buildings with dependent connection to external heating networks is considered, providing reliability of heat supply and the necessary comfort in the premises due to mixing in some of wastewater after hot water supply (DHW) heaters at an outdoor temperature exceeding the break point of the temperature graph. The main equations describing the dependence of the water temperature in the supply line on the outside air temperature are analyzed, and a review of possible ways of regulating the heat supply and preventing "overflows" near the beginning and the end of the heating period is carried out, taking into account the requirements of the current regulatory documents of the Russian Federation. Calculations are made to determine the required proportion in the mixture for water consumption after the heaters of hot water supply in the conditions of the application of the scheme of connection of buildings to the heating network. The analysis of obtained results is given, and conclusions are drawn concerning expediency of application of the considered scheme. It is established that, from the power point of view, mixing of wastewater after heaters of DHW in the calculated quantity will allow to provide reliability of heat supply of the main group of residential buildings and safety of activity of people at high temperatures of outside air. It is shown that, at the same time, that the higher the current outdoor temperature, the greater the share of wastewater in the mixture, with the above dependence close to linear, and its numerical coefficients associated only with the calculated outdoor temperature in the construction area for the cold season. It is noted that the introduction of the proposed scheme is possible with a minimum reconstruction of existing units and structures without significant capital costs, and also gives a system-wide effect in the form of increased electricity generation in thermal power plants on thermal consumption.

The problems are considered and the results of numerical modeling of the furnace processes of heat generators are discussed. In recent decades, designs of household generators to be placed directly inside premises tend to be made more and more compact, which increases the commercial attractiveness of products, but leads to a decrease in the size of the furnace and the deterioration of conditions for the development of the flame. Based on the methods of computational hydrodynamics, a study was carried out of the furnace processes in Unimat UT-L18 “Bosch”, “FEG” Beata 2 and Vitodens 100-W “Viessmann” heat generators. The combustion of mixtures of methane with air and oxygen is considered. Geometric models of furnaces corresponding to their design features are developed. The required boundary conditions of gas fuel combustion processes in them are determined. The temperature, velocity and concentration fields in the furnaces are presented. Special attention is paid to obtaining physically adequate distributions of aerodynamic and thermal characteristics of the flame zone for each of the models made. Thermal and aerodynamic correctness of numerical calculations are a necessary condition for the adequacy of calculations of methane oxidation. Obviously, without this, it is fundamentally impossible to discuss the perfection of furnace processes in the devices studied, and in this case it has an additional significance, since the interaction of the reacting components is calculated by the one-stage oxidation scheme. Therefore, products of chemical underburning are absent, and the rate of use of fuel can only be established from the concentrations of the initial and final reagents. According to the results of calculations with confirmed correctness, a comparison was made of the completeness of the process of oxidizing the combustible components of the air-fuel mixture in furnaces, which differ in the degree of flame constraint. The created models provided the possibility of quantitative analysis of the operation of the furnace and burner devices of these heat generators. The evaluation of the perfection of furnace and burner devices, made on the basis of the results obtained, will allow the use of the most advanced types of heat generators with increased efficiency in the projects of decentralized and individual heat supply systems for buildings.

The paper is devoted to relevant issue of raising the quality and reliability of rotor blades of steam turbines. This is due to the fact that the number of failures of rotor blades exceeds 60% of all failures of steam turbines, which are in operation. The developed method of control of stability of parameters and reliability of rotor blades during their manufacturing and testing is proposed to introduce in addition to the existing method of quality control of rotor blades of steam turbines. The methods of quality control of rotor blades during the process of their manufacturing and testing according to existing normative documentation are described in detail. The form 1 “List of defects, malfunctions and failures, which have been revealed during manufacturing and testing” and form 2 “Inspection chart of stability of parameters” have been developed in addition to normative documentation. The calculation equations for estimation of stability of parameters of technological processes and reliability level have been presented. A technique for determination of extreme deviation of parameters and regulation boundaries according to preset tolerance has been developed. An example of stability control of natural oscillation frequency has been presented. The presented technique has been implemented at special purpose enterprises. An internal certificate is drawn up for each set of rotor blades at the manufacturing plant with a view to gather statistical information. This certificate is developed by the manufacturer. Information about the material certificate, the results of control, which has been carried out during the process of manufacturing and testing, with indication of deviations from the draft, the technical specifications during the testing, the description of technological process of thermal treatment of stocks etc. are noted down in the internal certificate.