Vol 66, No 10 (2019)

The article discusses the possibilities for and results of structural changes in the electric power industry of Russia, which performs the integrating function for the country’s fuel and energy complex during its transformation in the context of various scenarios supposed for the world’s technological transition to the use of noncarbon energy in the period up to 2040. The optimal lines of technological progress and its acceleration rates in the industry, which ensure full replacement of the existing capacities of gas- and then also coal-fired power plants by new types of equipment, as well as noticeable increase in the share of noncarbon (nuclear and renewable) sources, are investigated. The effect that the choice of a more energy-efficient and diversified structure of generating capacities has on the consumption of energy resources and also on the direct and indirect effects for the national economy of Russia is estimated. For estimating the consequences from structural transformation of the electric power industry, the integral energy and economic characteristics of the conservative and innovative scenarios of its development are calculated. Based on these characteristics, a system of indicators for comprehensively estimating the industry’s development scenarios is proposed that reflect the extent of its technological renovation, energy efficiency, energy balance diversification, price load, and budgetary effectiveness. The results of applying the proposed system of indicators confirmed the advantages of the electric power industry’s innovative-development scenario. The following two strategic objectives can simultaneously be solved within the framework of this scenario in the period up to 2040. First, it will be possible to overcome the long-lasting technological backwardness of the domestic thermal power industry and reach the level of best technologies in gas- and coal-fired power generation. Second, it will be possible to ensure a very rapid growth in the scales of using noncarbon technologies (nuclear and renewable energy), thus setting up a background for achieving a situation in which they would account for up to half the electricity production by the mid 21st century. It is shown that the acceleration of technological progress in the electric power industry will compensate one-third of the losses in Russia’s economy due to decreased export of fuel when a shift is made around the world to noncarbon energy.

Heat and mass transfer processes and decomposition of organic compounds in a pyrolysis reactor are simulated using the ANSYS Fluent software package. Simulation of the pyrolysis of organic compounds, in contrast to simulation of their combustion, is dealt with only in a few studies. However, there are many engineering applications of this process, including thermal decomposition of various wastes where the use of pyrolysis, due to its specifics, seems to be very promising. Because of the wide variety of organic compounds, implementation of their processing in practice using the pyrolysis process depends heavily on the properties of a given feed and requires theoretical justification. A pyrolysis reactor equipped with a mixer is described, and the problem in the computer simulation of wetted polypropylene’s thermal decomposition is formulated. Polypropylene is a component of many medical products, such as catheters, transfusion systems, disposable syringes, etc. It has the highest decomposition heat among all components of medical waste and controls the maximum time of their decomposition. A description is given of a two-phase mathematical model consisting of the well-known mass, momentum, and energy conservation equations, mass transfer equation, and equation of state. The results from calculation of the propylene pyrolysis and the dynamics of thermal decomposition of a solid phase in a reactor are presented. The time of moisture evaporation and pyrolysis of a specimen at 600°С was determined. The hydrodynamic and heat transfer characteristics of the process enabling the performance of a thermal processing package and the requirements for the design of a test facility are considered. The results on the rate and time of polypropylene decomposition offer prospects for predicting the throughput capacity and loading frequency for the investigated reactor.

Problems in planning and implementation of the operating conditions for district heating systems (DHSs) are directly related to the controllability and permissibility of the conditions and the reliability, quality, and efficiency of the heat supply systems’ operation under various operating conditions. The operating conditions’ development should be aimed at minimizing operating costs related to implementing the operational modes taking into account the entire set of technical and technological restrictions. The decisive factor in implementing competent adjustment and planning DHS operating conditions is the performance of preliminary calculations directly by the operators. In this case, the condition-development engineer receives a computer model of the operating DHS at his disposal that allows justifying and conducting constant correction of the thermo-hydraulic conditions during the entire heating season under changing operational conditions. For example, when connecting new consumers, varying loads, and under forced changeovers caused by emergencies, they can calculate the postemergency modes and correct the control values when the operating variables exceed the permissible values. At the Institute for Energy Systems (Siberian Branch, Russian Academy of Sciences), a system of mathematical models and methods has been developed for calculating and analyzing the thermo-hydraulic conditions at DHSs. This system was implemented in the Angara-TS information–software package (ISP). The ISP an is integration of models, methods, and software with information technologies intended for automation of workplaces for condition-development engineers. Technology for developing operating conditions for large-scale DHSs that satisfy all technical restrictions, including the required heat supply level, is presented. The technology based on multilevel modeling has been verified when implementing the operating conditions of real DHSs in Irkutsk, Angarsk, Bratsk, Baykalsk, Petropavlovsk-Kamchatsky, and other cities. This article deals with the development of the operating conditions for the DHS of Cheremkhovo, a town in Irkutsk oblast, to supply heat power from a combined heat and power plant according to a new temperature schedule. Practical application of the technology developed for planning the real DHS operating conditions has revealed its great potential for energy saving and has significantly improved the quality of the heat supply. The operating conditions and adjustment measures developed using the Angara-TS information–software package allowed for a significant reduction in the circulating heating-medium flow rates, the consumption rate of the make-up water, the water drain by consumers, the energy consumed for transfer of the heating medium, and the cost of chemical water preparation and has ensured the required level of heat supply.

Piping heat insulation consisting of mineral wool as the main layer and a fiberglass cover is deformed and suffers damages during day-to-day operation. This increases the heat losses through insulation when a heat carrier flows through the pipeline. This investigation is devoted to the use of a thin-film coating (TFC) in the arrangements of existing conventional heat insulation on heating networks to improve the insulation’s effectiveness and reduce the heat losses. The effectiveness of a TFC was evaluated experimentally in a model section of a pipeline that enabled us to simulate actual operating conditions of the piping in a heat supply system. The experiment is based on the determination of heat fluxes flowing through the heat insulation of a pipeline using an infinite cylindrical layer method. To theoretically substantiate the energy-saving effect from the application of a TFC, a numerical investigation of thermal processes occurring within the insulation was performed. Since the considered type of insulation is air-permeable and the permeability depends on the state of the main and cover layers, the effect of convection on heat transfer in the porous insulation with a permeable cover on heating network piping was numerically studied. The effect of a TFC on thermal processes and effectiveness indices was analyzed for two methods of a heating network’s installation: indoors or outdoors. The results demonstrate that it is advisable to use a TFC in the existing heat insulation to improve its effectiveness and reduce thermal energy losses due to a decrease in the heat fluxes by 17% after application of the TFC. The numerical predictions suggest that indoor pipelines should be provided with one TFC layer, while outdoor pipelines should be coated with at least two TFC layers.

The demineralization of clarified water is carried out in TPPs, NPPs, and combined-cycle boiler houses in Russia, as a rule, using a chemical or membrane method. Conventional chemical demineralization prevails, and the number of reverse osmosis plants is constantly increasing. When choosing the demineralization technology, the main criteria are economic. When comparing the reduced costs for water demineralization, chemical ion exchange methods take precedence over others for low-mineralized waters prevailing in the central and northern parts of Russia. For medium-mineralized waters, the economic indicators of ion-exchange and reverse osmosis demineralization are close. In terms of environmental performance, membrane water treatment technologies have significant advantages over the ion-exchange method; however, they require more thorough water pretreatment and are characterized by an increased sewage flow rate of up to 40% of the capacity. The introduction of more advanced technologies on conventional water treatment plants with parallel-flow filters reduces water consumption for plant demand, ion exchangers and reagents, primarily acids, and alkalis. This article uses the results of a survey of water treatment plants at some TPPs. Technical and economic indicators are given for groups of power plants that are grouped according to the same principle of water treatment technology. It is concluded that conventional chemical water demineralization plants with straight-flow filters have not exhausted their capabilities. Counter-current ionization technologies can successfully compete with conventional installations, provided domestic enterprises master the production of complete filters, including the automatic control system. Membrane water demineralization technologies can be effectively used in the energy sector for the development of industrial design, application, and process flow tests’ regulations for reverse osmosis plants.

The article considers the specific features of and prospects for improving the efficiency of geothermal power plants (GeoPPs) that use a steam–water mixture from geothermal fields and steam superheating as an energy source. The process flow diagram of a combined binary-cycle GeoPP with two separation pressures and flashed steam superheating with the use of a hydrogen–oxygen steam generator is proposed. The advisability of using a separator downstream of the high-pressure section for decreasing the steam moisture at the turbine condenser inlet is substantiated. The article also presents the results from numerical optimization investigations of the effect that the choice of organic working fluid has on the efficiency, safety, and environmental characteristics of the binary installation used as part of a combined-cycle GeoPP. The following groups of organic substances as possible candidates for use as working fluid are considered: nontoxic, nonflammable, and nonexplosive ones (group I); low-toxic, nonflammable, and nonexplosive ones (group II); nontoxic inflammable ones (group III); and low-toxic, inflammable, and explosive ones (group IV). Typical dependences characterizing the effect that the pressure in the expander and the saturation pressure in the evaporator have on the binary turbine net power output, on the specific flowrate of separated geothermal brine per unit power capacity, on the binary cycle efficiency, and on the GeoPP efficiency as a whole are shown taking as examples the use of cyclobutane and octafluoropropane as a working fluid. For a few working fluids, the existence of extremes in the above-mentioned dependences is established, which determine the binary installation optimal power values and the minimal geothermal brine specific flowrate. Based on the numerical analysis results, limitations are imposed on the admissible maximum and minimum pressure values in the binary circuit. Bar charts of calculated process characteristics influencing the binary turbine flow path’s design and efficiency are plotted. A priority (according to the maximum net power output criterion) list of working fluids relating to the group of environmentally friendly organic substances for the combined-cycle GeoPP binary installation with flashed steam superheating taking into account process-related limitations is drawn up.