Vol 26, No 4 (2022)

This paper discusses the development of a new procedure for finishing and hardening treatment by changing the kinematics of a deformation tool having a double-radius shape of the profile of the working surface, along with the determination of the stress-strain state in the site of elastic-plastic deformation and residual stresses in the hardened zone of the surface layer. The SOLIDWORKS 2018 software for 3D design and the ANSYS Work-bench 19.1 soft-ware using the finite element method were used to build a mathematical model of local loading. The temporary and residual stresses, the strain state in the loading zone, the depth of the plastic layer and the maximum value of the relative plastic deformation under various loading procedures of the working tool were determined. It was established that, at the reversible rotation of a double-radius roller, the values of temporary stresses are over 15% higher compared to those during static hardening, while the residual stresses are 5.7% higher. With the reversible rotation of the double-radius roll-er, the value of the maximum strain intensity becomes 2.11 times higher than that during static hardening. The intensity of the maximum residual stresses during the reverse rotation of the double-radius roller occurs at a depth 3 times greater than the indentation of the double-radius roller, rather than on the surface of the sample. The results of computer model-ling and numerical calculations indicate that the procedure of reversible rotation of a toroidal double-radius roller has the greatest influence on the intensity of the stress state in the deformation site, while the procedure of static hardening by a single-radius roller has the least impact. The obtained results suggest that the proposed technological process of surface plastic deformation based on the reversible rotation of the working tool will allow the radial tension to be reduced while maintaining the high quality of the surface layer of machine parts.

A developed methodology for evaluating measurement uncertainty during the tensile tests of metals and alloys is presented. In this connection, the various sources of uncertainty are considered. The object of studies included high-strength bolts made of 40Kh “Selekt” steel, which were subjected to tensile tests according to the GOST 1497-85 State Standard using a UMM-100 universal tensile testing machine. The basic sources of uncertainty in the measurement of relative elongation and reduction were shown to include repeated measurements of relative elongation; errors of measuring the finite length by a vernier calliper and marking the initial length of a calculated section, as well as the measurement error of the tensile testing machine. These also include operator reading error, repeated relative reduction measurements, as well as the error of measuring the sample diameter by a micrometer before and after the tests. During the measurements, temperature deviation was demonstrated to constitute an additional source of uncertainty when the ambient temperature is different from the standard temperature value ((20±5)°C). Assumptions underlying laws describing the distribution of input values were assigned. Tensile tests are shown to be characterised by two components of uncertainty evaluated as types A and B. A mathematical model constructed for measuring relative elongation and relative reduction during tensile tests is presented. The standard uncertainties of input values are evaluated based on the assumed laws of their distribution. A correlation between the final length of the calculated section, the diameter of the sample following the test, and the applied force, is revealed. Expressions for the calculation of sensitivity coefficients, which characterize variations in the output value (relative elongation) depending on variations of input values, were obtained. The total and extended measurement uncertainties were evaluated. Based on the performed studies, a procedure for evaluating measurement uncertainty when carrying out tensile tests of high-strength bolts was described. The evaluation of measurement uncertainty during the product testing was shown to be a rather labourconsuming work. In this regard, the authors propose the development of procedures for evaluating the measurement uncertainty during the tests with their inclusion into regulatory documents for control methods.

In this work, an approach for accounting and regulating the share of distributed generation in an integrated energy system is developed. In order to model an integrated energy system, a multi-agent approach was used, which presents a technologically complex system as a combination of agents, each having individual behaviour. The essence of a multi-agent approach is as follows: an integrated energy system is represented as a combination of components modelled by their agents having an individual behaviour algorithm; each element of an integrated energy system is involved in the generation of a solution and protects its interests on the basis of efficient energy supply. The implementation of this approach was carried out using the AnyLogic software environment, which includes the basic components of agent and simulation modelling, allowing any multi-agent systems to be developed depending on the application. The custom structure of the multi-agent system for integrated energy systems was developed, factoring in its performance features and interaction of objects, the main composition and types of agents of the multi-agent system being determined. The following types of agents were distinguished: consumer agent, dynamic consumer agent, network agent, manager agent of dynamic consumer, agent of centralised energy source, network agent and advisory agent. A multi - agent model of a real power supply system of a residential area in Irkutsk, having centralised and distributed energy sources, was developed. Taking into account the efficient operation of centralised energy sources, the principles for regulating the share of distributed generation in the system were proposed, allowing the total costs of energy supply to consumers to be reduced by rearranging power between centralised and distributed generation sources. The results obtained using the developed multi-agent model were used to formulate the principles of interactions of centralised and distributed energy generation sources. The redistribution of power between these energy sources on the basis of the above principles reduced the total costs by 4.22% for heat supply and 9.94% for electricity supply to consumers.

The present study considers solutions to problematic issues concerning the integration of distributed generation facilities into the internal power supply network of power consuming units. The possibility of ensuring reliable power supply using verified models of generating plants and power consuming units is analysed along with a description of principles for the selection of control systems for generating plants. Full-scale measurements recording significant deviations in power quality indicators, were carried out. A total capacity of distributed generation facilities operating as a part of isolated energy districts is estimated at 8.5–9 GW. In addition, in the case of operation as a part of power systems, this capacity is equal to 13.5–14 GW. Therefore, the total capacity of these facilities is 22–23 GW or 9.5–10% of the total capacity of all generating facilities in Russia. The necessity of using verified mathematical models of generating plants, as well as main synchronous and asynchronous motors, along with the correct consideration of rotated mechanism types and real load factors, is substantiated. Principles for selecting the excitation systems of generating plants, as well as coordinating parameter settings for relay protection devices in generating plants and other elements in the internal power supply networks of power consuming units are considered. Recommendations regarding the permissibility of commutations and guaranteed correspondence between electric power quality indicators and regulatory requirements in island (autonomous) operating mode are provided. Thus, the need on the part of organizations that have necessary software systems and experience in conducting complex mode calculations to implement projects for integrating distributed generation facilities is substantiated. Here, the volume and complexity of calculations is higher than in the design of standard power plants and power supply systems.

The paper aims to stabilize the roasting of zinc sulfide concentrates in fluidized-bed furnaces using oxygen- enriched air. The balance between the given excess air blast (on average 20%) and the amount of loaded charge is achieved by selecting an appropriate number of evaporative cooling elements in the fluidized-bed furnace. Through the evaluation of scientific and technical information, as well as literature sources on the research topic, data were collected on the effects produced by an oxygen excess in the blast on the quality of sulfide concentrate roasting and by a blast volume on the state of the fluidized bed. In addition, statistical data for the study were obtained by analyzing the operation of fluidized-bed furnaces at Electrozinc. As part of the study, the heat balance in roasting was determined, taking into account the following technical characteristics of fluidized-bed furnaces used for roasting zinc sulfide concentrates: fluidized- bed level, number of nozzles, furnace diameter, diameter in the bed zone, hearth thickness, and the total weight of the furnace. Relying on the operation analysis of fluidized-bed furnaces, a method was proposed to regulate the oxygen supply depending on the amount of loaded charge. The oxygen supply is regulated in order to ensure a stable excess of oxygen in the blast without causing any significant changes in the blast volume and, consequently, to maximize the sulfur removal from the charge. A decrease in the excess air blast below 15% was found to significantly degrade the quality of the resulting cinder and dust, while an increase of over 20% reduced the SO2 content in the exhaust gases with no noticeable improvement in the quality of cinder. Therefore, the proposed method for regulating the oxygen supply to the furnace can improve the techno-economic performance of zinc sulfide concentrate roasting in fluidized-bed furnaces.

A theoretical substantiation of an environmentally friendly technology for extracting gold from mineral raw materials is presented. In terms of an alternative to conventional cyanide, the authors propose chlorine-bearing derivatives of organic isocyanuric acid (C3H3N3O3). In the studied process, this reagent combines the roles of a long-acting oxidant and complexing agent due to the resulting Cl– ion. For experimental purposes, the rotating disc technique was applied. Experimental results were evaluated by measuring the concentration of gold in solutions using the atomic adsorption method. The theoretical characteristics of gold dissolution using the proposed reagent were studied. In order to evaluate the applicability of the revealed regularities for practical purposes, comparative indicators for leaching gold from the ore of the Byn’govskoye deposit (Sverdlovsk Oblast) using the proposed reagent, cyanide and CYCAD cyanide substitute (China) were evaluated. The dependence of the gold disc dissolution rate on temperature, as well as leaching reagent and hydrochloric acid concentrations, were studied. In disc sample experiments, the exponential dependence of the dissolution rate on the concentration of the studied reagent was established. In this case, the maximum intensity of the process is achieved at a concentration higher than 50 g/dm3. The optimum acidity level comprises 0.3–0.4 g ion/dm3 of hydrochloric acid. Despite an increase in temperature being shown to accelerate the dissolution process, this appears to be technologically unjustified. Under optimal conditions, the gold disc dissolution rate reaches 0.5•10-3 g ion/(cm2•min), which is approximately one hundred times higher than during the dissolution by the cyanic solutions in conventional modes. Close gold extraction values were achieved in the solutions of cyanides and chlorine-bearing derivatives of isocyanuric acid during the leaching of gold from the ore under the comparable conditions. For CYCAD solutions, the same indicator is two times lower. The results of the performed studies demonstrate the high dissolution rate of gold using the proposed reagent along with the technological possibility of leaching gold from ores using this environmentally friendly reagent.

This paper examines the kinetics of corrosion for steel St3 samples covered with a latex coating 69B–2k, manufactured by Kapitel LLC (Irkutsk), by analysing gravimetric tests performed using steel samples. A 3 wt % solution of sodium chloride was used as an electrolyte. The accuracy of the obtained results was confirmed by carrying out at least two parallel experiments. Prior to coating, the metal surface of samples was carefully prepared as per GOST R 9.907-2007. Film coatings were applied onto the metal surface by threefold dipping of samples in liquid latex followed by drying within 24 hours. The quality of the coating prior to and following the experiments was assessed visually and by microphotography. Gravimetric studies were carried out under temperature control (25 ± 0.2°C) in the working area. At the same time, changes in the sample mass were recorded over a controlled time interval (from 1 to 24 hours). The results of weighing samples obtained prior to and following the experiments were analysed using a kinetic flowchart, in which the type of reaction is defined in stages in a natural sequence. Kinetic analysis of the gravimetric results confirmed the absence of characteristic signs associated with chemical interactions on the surface of steel St3 coated with latex 69B-2k. Out of the known mathematical models of phenomenological kinetics, it is admissible to use a first-order equation to describe the course of a simple reaction during heterogeneous interaction, where the penetration of reagents through a latex film comprises a limiting stage. The kinetic analysis showed that it is necessary to study the properties of latex films; a strategy for further corrosion studies was determined.