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No 5 (2024)
Articles
Methodological provisions to the formation and the ensuring of efficiency and reliability of district-distributed heating systems
Abstract
This study proposes a methodology for solving two problems of optimal development of district heating systems: analysis of efficiency areas and reliability of heat supply. In solving both problems, we adopt a nodal approach, which allows us to get detailed results that are most suitable to the real-world conditions. Based on the proposed methods and models, we develop an algorithm for transforming existing district heating systems into district-distributed heating systems with prosumers implemented into the network to serve the loads that fall outside the range of efficient operation of a district heating system. Wherein, the distributed sector is formed based on a prosumer that has its own generation, covering part of its own heat load and providing an additional functional and time redundancy for the system. As a result, conclusions and directions for further research are formulated.
3-14
Reproduction оf the mineral resource base оf the energy sector аs оne оf the main aspects оf Russia’s energy security ensuring
Abstract
The article characterizes the situation with the production and consumption of primary fuel and energy resources in Russia for the period 2021–2023. The main emerging trends are shown and the main threats to energy security are characterized, including the threat of deterioration in the quality of reserves of the mineral resource base of the fuel and energy complex. The main objects of indicative analysis declared in the Doctrine of Energy Security of the Russian Federation are shown, among which an important place is occupied by the object “Ratio of the increase in balance reserves of primary fuel and energy resources to the volumes of their production”. Based on data on the dynamics of reproduction of reserves of natural gas, oil, coal and uranium for the upcoming five-year period, the values of the most important indicators of this object are determined and an idea of the final qualitative assessment of the situation for the entire object of analysis is formed. The article analyzes the main reasons and draws conclusions about the emerging trends in the renewal of industrially extractable reserves of the main primary fuel and energy resources and the possible consequences of a worsening situation.
15-26
Assessment оf the level оf energy security оf regions in emergency situations in the gas industry using the example оf the Northwestern Federal District
Abstract
The article presents an assessment of the energy security level using the example of the subjects of the Russian Federation located in the Northwestern Federal District. The approach to the assessment is based on the use of the apparatus for monitoring and indicative analysis of energy security (ES) developed at the ISEM SB RAS. An assessment of the ES level in the regions is carried out based on modeling the situation with the cessation of operation of the most important gas industry facilities, and an analysis of the dynamics, scales and trends in the change in the state of the ES level is carried out when modeling the situation using peak UGS facilities provided for by the General Scheme for the Development of the Gas Industry for the Period up to 2030 for the analyzed subjects of the Russian Federation.
27-41
Selection оf energy sources for prosumers in the centralized heat supply system using agent technologies
Abstract
In recent years, the energy sector has been widely developing the direction associated with the introduction of distributed energy generation and the emergence of prosumers (PR), including within the heat supply system. Due to the emergence of consumers as participants in energy markets who take an active part in the process of managing their energy supply, there is a need to make decisions on energy supply options in the context of conflicting interests of the parties - the PR and the centralized heat supply system (CHS). The article presents a mathematical formulation of the problem of finding a compromise solution, which includes an PR model, a CHS model and a generalized desirability criterion. A methodology for selecting energy source equipment for PR in the CHS has been developed, taking into account the interests of the CHS and PR and their ability to produce heat energy. A structure of a multi-agent system is proposed and agent behavior algorithms are developed that take into account the complex behavior of the PR and CHS objects. The results of testing the developed methodological and software on a test model of the heat supply system are presented.
42-58
Model representations of the theory of thermal shock of viscoelastic bodies
Abstract
Model representations of the theory of thermal shock of viscoelastic bodies based on two different approaches are considered. In the first approach, based on the introduction of stress and strain deviators using linear rheological models of Maxwell and Kelvin, new integral and differential relations are proposed, including simultaneously dynamic and quasi-static models for viscoelastic and elastic media, generalizing the results of previous studies. The proposed constitutive relations of the new form are applicable to describe the thermal response of bodies of canonical shape, limited by the boundaries of a rectilinear shape in Cartesian coordinates and are extended to the case of curvilinear boundaries in cylindrical and spherical coordinates. The second approach describes an elastic-viscoelastic analogy, which consists in the fact that the original problem of temperature stresses of a viscoelastic body can be reduced to the equivalent problem of thermoelasticity by replacing the shear modulus and Poisson’s ratio in the operational (according to Laplace) solution of the thermoelastic problem with their images as in the model Maxwell and in the Kelvin model. It is shown that after performing the inverse transformation, an analytical solution to the problem for a thermoviscoelastic medium is found. An illustrative example is given and the differences in the thermal response to sudden heating of an elastic and viscoelastic medium are analyzed.
59-73
Assessment of the influence of thermal characteristics of non-design lignite on their suitability for combustion in the furnace of an energy boiler
Abstract
The possibility of burning various brown coals (LC) in the furnace of the BKZ-420-140-6 boiler was studied using numerical simulation. To check the compiled numerical model of solid fuel combustion, it was previously validated in relation to the combustion of BU of a certain composition by comparing the calculation results with data obtained during the operation of a real boiler.
A method was developed for averaging the characteristics of coal and dependencies were obtained that determine the composition of coal based on an analysis of the composition of 14 types of coal in the range of values of the lower calorific value from 7.5 to 16 MJ/kg. Based on the obtained dependencies for 4 values of , the theoretical average composition (ATC) of coals was determined. For one of the TUSs, the humidity varied by 10% up and down.
As indicators of the efficiency of the combustion chamber of the boiler, the temperature of the gases at the exit from the combustion chamber, mechanical underburning and the concentration of nitrogen oxides in the flue gases are taken. The results of numerical modeling show that with the calorific value of the fuel ≤10 MJ/kg, the mechanical underburning q4 exceeds the permissible standards. The highest concentration of nitrogen oxides at the level of 800–900 mg/nm3 is observed for brown coals with high and the highest carbon content. It is also shown that the use of direct-flow burners with the organization of staged fuel combustion makes it possible to reduce the formation of nitrogen oxides in the furnace by 3.25 times compared to the original combustion scheme using existing vortex burner devices. The influence of the lower calorific value of fuel on the gas temperature at the exit from the combustion chamber in the range from 11.75 to 16.45 MJ/kg is insignificant. The effect of increasing fuel humidity on the gas temperature at the outlet of the combustion chamber and on mechanical underburning is insignificant up to a working fuel humidity of approximately 45%. In general, studies have shown that the firebox under consideration allows the combustion of various brown coals with changes in the physico-chemical composition and thermal characteristics within a wide range.
74-87
Numerical simulation оf coal combustion in the combustion chamber of a boiler unit
Abstract
The paper presents the results of numerical investigation of physico-chemical processes in the furnace chamber of a steam boiler during flaring of polyfractional solid fuel. Given the presence of two-phase flow, the application of the QUICK quadratic upward interpolation scheme and the monotonicized counterflow MLU scheme for discretization of the spatial and temporal step of the convection-diffusion equation is considered. The simulation results in general reveal a good convergence of the numerical simulation results with in situ measurements when using the considered approximation schemes. At the same time, it is shown that, when using the QUICK scheme, deviations are observed in regions with large gradients, leading to the propagation of the calculation inaccuracy to subsequent domains. In both versions of the simulation, zones contributing to high-temperature corrosion were identified.
88-100