Combustion Chamber Of Boiler Research Articles

Оценка эффективности завихрения воздуха при распылении водоугольных суспензий пневматической форсункой

Due to modern requirements for environmental protection, introduction of environmentally friendly power engineering technologies involves search and development of new energy sources. One of the ways to meet these requirements and maintain the same level of energy production by thermal power plants is to use multicomponent fuels. The most promising and affordable heavy fuel oil from the point of view of energy, ecology and economy are coal-water slurries (CWS). In this regard, the study of the properties and characteristics of such fuels is relevant. The coal-water slurries have been prepared in a rotary hydrodynamic cavitation generator. A pneumatic atomizer with external mixing is used to spray the coal-water slurries. Interferometric Particle Imaging method is used to determine the average size of fuel droplets after atomization. The authors have conducted experimental studies of the characteristics of atomization of coal-water slurries based on lignite and pyrogenetic liquid with a pneumatic atomizer with a tangential supply of a spraying agent. A three-stage method to prepare lignite-based slurries with pyrogenetic liquid has been tested. It has been established that when using this technique, the fluidity of coal-water fuel is maintained even with the introduction of 20 % by weight of pyrogenetic liquid into the composition of coal-water slurries when replacing both water and coal in equal proportions. The kinematic viscosity of coal-water suspensions increases when pyrogenetic liquid is added, despite a decrease in the concentration of the solid component. The change of suspension density is insignificant. The results of the study of atomization process have shown that the tangential air supply to the atomizer leads to an increase of the jet spraying angle by 6° compared with direct supply. At the same time, the average droplet size in the jet of a two-component CWS with direct air supply is 8 % smaller. The results of the study have made it possible to obtain completely new knowledge that can significantly advance domestic and world science and technology in the field of power engineering, namely the technology of coal-water fuels atomization. Experimental studies have determined the main patterns of influence of the CWS properties and the method of spraying agent supply on the formation of a gas-drop jet. Such patterns will provide conditions for the effective atomization of quite viscous CWS in the combustion chambers of energy boilers. The results obtained will enable designers and constructors to develop highly efficient designs of steam and hot water boilers and gasifiers fueled by CWS.

3D reconstruction of nonuniform and unsteady flow velocity distribution using nonlinear acoustic ray tracing and tomography

The nonuniform and unstable gas flow distribution at the air inlets of the boiler combustion chamber can negatively affect the energy efficiency and safety of the boiler. Accurately reconstructing the flow velocity inside the furnace in three dimensions can help the boiler automatically adjust the air supply to reduce unwanted energy waste and gas emissions.In this study, we propose a novel method for three-dimensional velocity reconstruction based on nonlinear acoustic ray tracing and tomography. The model provides the equation of acoustic ray motion in the flow field, which includes spatial and temporal parameters. During the process of measuring flow velocity, higher precision reconstruction of the three-dimensional velocity distribution was achieved by combining acoustic refractive paths based on derivative-free optimization iteration updates with radial basis functions that use Gaussian kernels.The computational time cost and reconstruction accuracy of the proposed algorithm were analyzed numerically and through simulations. The results indicate that the method incorporating acoustic ray tracing greatly improves the reconstruction accuracy of large gradient nonuniform flow fields. Additionally, we analyzed the impact of different numbers of sound tracing paths on reconstruction quality and computation time, providing a reference for the rational placement of microphones and the selection of the most efficient paths in boilers.Experimental results show that this method has good reconstruction capabilities for nonuniform flow fields and practical applications.

The use of plasma technologies to optimize fuel combustion processes and reduce emissions of harmful substances

The latest information technologies and 3D computer modeling methods were used to introduce new technology of plasma fuel ignition and stabilization of combustion processes. Numerical studies of the physicochemical processes occurring during the combustion of pulverized coal fuel flows in areas of real geometry (combustion chambers of thermal power plants) have been carried out. The main regularities of the influence of thermochemical plasma activation of pulverized coal flows on the process of fuel combustion in the combustion chambers of Kazakhstan boilers have been established. The conducted studies of the systems of thermochemical plasma activation of pulverized coal flows have shown the possibility and efficiency of their application at real thermal power facilities. This makes possible to solve both: economic problems (reducing the consumption of fuel oil) and environmental problems (reducing harmful dust and gas emissions from the combustion of low-grade coal fuels from Kazakhstan deposits). This will optimize the processes that occur during the combustion of energy fuel, reduce emissions of harmful substances into the atmosphere (carbon oxides, nitrogen oxides), create and implement in the future a new way to produce "clean" energy.

Experimental methods for assessing the materials quality of lining for the ship boilers combustion chambers

Autonomous boilers, the most important element of which is the combustion chamber, are widely used in ship power plants. A necessary condition for a high resource of boilers and their trouble-free operation is the high quality of the lining of the furnace space, operating under variable thermal conditions. The quality of the material from which it is made has a decisive influence on the reliability of the lining. The methods of experimental research that can be used to assess the quality of materials for lining the furnace spaces of autonomous boilers are described in the paper. The methodology of conducting research using the method of equivalent materials is presented, laboratory installations for conducting vibroacoustic studies and modal analysis of spectrograms and thermal imaging studies of samples of lining materials are described. As a result of the research, information on the influence of conditions for the formation of equivalent materials samples on their thermophysical properties, spectrograms of the state of brickwork bricks made of various materials, thermal images of lining elements in a stationary temperature field at different locations on the heater is obtained. The results obtained indicate the expediency of using the proposed methods at all stages of the life cycle of autonomous boilers: when designing for a rational choice of lining materials taking into account operational factors, during manufacture and repair during operation to control the quality of materials used and detect hidden defects. In order to increase the effectiveness of the proposed experimental methods for assessing the quality of lining materials of boiler combustion chambers, it is necessary to expand the practice of their use, the accumulation of the results obtained and their statistical processing, which allows us to determine the error of the methods and improve laboratory installations.

STUDY OF THE AERODYNAMICS OF THE FLOW OF THE COMBUSTION CHAMBER OF A POWER PLANT WITH VARIOUS SUPPLY OF SOLID FUEL

Numerical modeling methods have been used to study the effect of an emergency stop of the fuel mixture supply through individual burners on the aerodynamics of the flow in the combustion chamber of a power boiler. The performed computational experiments made it possible to obtain the main aerodynamic characteristics of heat and mass transfer processes (full velocity vector, pressure, kinetic energy of turbulence and dissipation energy) in the volume of the combustion chamber and at the exit from it in emergency mode (two swirl burners are operating) and compare them with traditional solid fuel combustion (basic mode - four direct-flow burners are working). The results obtained indicate that with a vortex fuel supply in the central region of the combustion chamber, a sharp change in aerodynamic characteristics is observed with the formation of a vortex flow, which weakens as the pulverized coal flow and combustion products move to the exit. The presence of a vortex flow causes stable combustion of solid fuel and uniform distribution of heat flows along the walls of the combustion chamber. In addition, the vortex nature of the flow increases the residence time of coal particles in the combustion chamber, which contributes to a more complete burnout and a decrease in the mechanical underburning of the fuel mixture. Such a detailed study of the aerodynamic flow pattern that takes place in the combustion chamber of power boilers of operating TPPs can only be obtained by numerical simulation methods and by performing computational experiments. The highly informative results obtained make it possible to develop “clean” energy production technologies and solve environmental problems of the emission of harmful substances into the environment.

Co-Firing Combustion Characteristics of Woodchips and Spent Mushroom Substrates in a 400 kWth Stoker-Type Boiler

The simultaneous firing characteristics of woodchips and spent mushroom substrates (SMS) were studied in a stoker-type industrial boiler. The type of spent substrate intended for combustion consisted of oyster mushrooms. SMS from mushroom farms generally have a high water content. Dryers are therefore used for combustion. The moisture content of SMS was reduced to achieve low moisture to combust sufficiently at about 20%. First, the basic characteristics of the boiler were confirmed by conducting a woodchip combustion test under various operating loads of 30, 50, 70, and 100%. Thereafter, a simultaneous combustion test of woodchips and SMS was performed. During the experiment, exhaust gas concentrations in the boiler combustion chamber were measured, such as the temperature of oxygen (O2), carbon monoxide (CO), and nitrogen oxides (NOx). In addition, industrial and basic analyses were performed on woodchips and SMS. The main differences in the fuel analysis results between woodchips and SMS were ash, nitrogen, sulfur content and net calorific value. According to the analysis, the nitrogen content of SMS was 2.6%, which was 8.7 times higher than that of woodchips, and the ash content was also 14.8%, which was 18.5 times that of woodchips. As a result of the combustion experiment, the woodchip experiment revealed that the values of O2 and CO decreased and the combustion chamber temperature increased as the amount of fuel increased. Due to higher combustion temperature, thermal NOx also increased. When comparing this combustion test with the co-firing test, there was no significant difference in O2, CO, and combustion chamber temperature. However, with regard to the NOx value, the results showed a sharp increase from 64 ppm to 135 ppm. Although the NOx value increased, SMS had enough heat to be burned as fuel. Therefore, the utility of various agricultural byproducts as fuel has prospects for achieving an effective approach to energy cost reduction.

The flexible boiler operation in a wide range of load changes with considering the strength and environmental restrictions

Thermal steam units cooperating in one power system with wind and photovoltaic farms must have high flexibility, i.e., operate over a wide range of load variations, typically between 40 and 100%. In addition, the start-up and shutdown time of the unit should be short. Thick-walled pressure components that limit the fast start-up of the units are turbines, steam boilers, and pipeline branches due to the occurrence of high thermal stresses in them. This paper determines the allowable heating rates of thick-walled components of a 97.22 kg/s natural circulation steam boiler. The boiler drum is the critical element, with a heating time of about 6000 s from the cold state. Computer simulations of the boiler combustion chamber were also performed at three different loads, i.e., 100, 60 and 40%. The calculations show that the maximum emissions of harmful substances do not exceed the permissible values given in European regulations: CO≤140mg/mn3 and NOx≤100mg/mn3. The maximum content of CO = 136.8 mg/mn3 occurs at 60% boiler load. The maximum content of NOx = 217.3mg/mn3 in the exhaust gas upstream of the SCR (Selective Catalytic Reduction) system occurs at 40% load, but downstream of the SCR system is reduced below the limit value 100mg/mn3.

Теплообмен в охлаждаемых камерах сгорания теплогенераторов малой мощности

Introduction. The study of heat exchange in cooled combustion chambers and the influence of various factors on its intensity is a complex and relevant task. The analysis of theoretical and experimental data on heat exchange in combustion chambers of various plants has proven that current methods fail to take into account features of heat exchange in furnaces, having small geometric dimensions and, therefore, they cannot be used for their thermal calculation. Materials and methods. The author presents the experiments and the results of their generalization performed using the criterial equation. Generalization results are of great importance for analyzing heat transfer processes and the thermal analysis of cooled combustion chambers of small capacity heat generators. The contribution of radiative and convective components to complex heat exchange processes in combustion chambers of low-capacity boilers is evaluated using this generalized dependence. The author has identified qualitative and quantitative dependence of integral radiative and convective heat exchange on the main factors of operation of small combustion chambers. Results. The author has obtained generalizing criterial dependence that makes it possible to evaluate the contribution of radiative and convective components to complex heat exchange in combustion chambers of low-capacity boilers. Conclusions. The generalized criterial dependence, obtained by the author, can be used to identify the qualitative and quantitative dependence of integral radiative and convective heat transfer on the main geometric, physical and performance factors of operation of small capacity furnace chambers. The assessment of reliability of the experimental data, obtained by the author, has shown that the value of the limiting mean square error of determining the value of integral heat transfer Kh.t will be 3.24 %. For all experiments, the deviation of the calculated data from the experimental results with a 95 % probability does not go beyond the confidence interval of ±9.52 %.

Investigation of the Optimal Tightness of the Combustion Chamber of a Solid Fuel Boiler in Order to Increase its Environmental Friendliness

Investigation of the Optimal Tightness of the Combustion Chamber of a Solid Fuel Boiler in Order to Increase its Environmental Friendliness

A new software program for monitoring the energy distribution in a thermal waste treatment plant system

The paper presents a novel system for monitoring the operation of a thermal waste treatment plant. The computer program is based on measurements of pressure, temperature, and mass flow rate of the working medium. The boiler efficiency is calculated using an indirect method. Thermal online calculations of the boiler combustion chamber make it possible to determine the heat flow rate to the evaporator. Based on the energy balance of the boiler evaporator, the superheated steam mass flow rate is determined, taking into account the mass flow rates of water injected into steam attemperators. By comparing the calculated and measured value of steam mass flow rate, the calorific value of the fuel fed is determined. The developed system enables monitoring of energy flow rates in individual elements of the power unit, taking into account losses in the boiler and turbine condenser. The following parameters are determined online, the efficiency of the boiler and the entire incinerator, heat losses in the boiler and the turbine condenser, as well as the heat flow rate, supplied to the municipal district heating system. By monitoring the plant operation, it is possible to adjust online the optimum excess air ratio.

Experimental and computational evaluation of a gas-solid suspension density distribution under circulating fluidized bed conditions

The paper presents the results of operational measurements of the suspension density distribution in the 966 MWth supercritical Circulating Fluidized Bed boiler. The tests were carried out for four different unit thermal loads, i.e. 40, 60, 80, and 100% MCR. The conducted operational measurements showed that the suspension density distribution of the particulate material in the combustion chamber of the CFB boiler has the form of an exponential curve with maximum values occurring in the bottom part of the furnace. On the basis of the operational data, an attempt was made to reflect the suspension density distribution in the combustion chamber of the boiler using the ANSYS CFD software. The calculations were carried out using the Eulerian multiphase model in an unsteady state condition. As revealed by the simulations, the Eulerian multiphase model allows for a quantitative representation of the suspension density distribution of the granular material only for the maximum boiler load. For other thermal loads, quantitative representation of experimental distributions of suspension density using the Eulerian method is possible except for the dense region.

Simulation of Nitrogen Oxides Formation as Air Pollution on the Example of Real Combustion Furnace

As in other countries in Central and West Asia, most of Kazakhstan's power plants have reached their potential as they were built mainly during the Soviet era. In this regard, it is important today to optimize coal consumption processes, introduce new environmentally friendly technologies and reduce emissions. And it is impossible without conducting detailed studies of the combustion of fuels in the combustion chambers of energy devices. It can provide complete information about the nature of complex processes of heat and mass transfer without special financial, time and labor costs. The existing models of the formation and destruction of nitrogen-containing substances NOx do not have a universal nature of use, since the fuel and combustion conditions are different. In this regard, the proposed work considered two models that are widely used. The aim of this work is to select a model that actually can describe the processes of dioxin formation in the combustion chamber of a real CHP boiler when high ash content coal is burned in it. The results of the simulation were verified with the data of field experiments, which allows an objective conclusion to be made. The obtained research data and the method of applying the selected optimal kinetic scheme of dioxin formation contribute to the development of new and optimization of existing measures to control environmental pollution

Using Plasma Activation to Optimize the Combustion Process and Minimize Harmful Emissions

AbstractThe possibility of introducing plasma ignition of fuel in combustion chambers of power boilers was investigated by using 3D computer modeling methods. Computational experiments were carried out on operating boilers, and a comparison of the characteristics of the combustion process for traditional fuel combustion and its thermochemical variant was carried out. Plasma technology allows the concentration of carbon and nitrogen oxides at the outlet of the furnace to be reduced. The results obtained showed the efficiency of thermochemical plasma activation of fuel and the possibility of its application in real heat and power facilities to optimize combustion processes and minimize harmful emissions.

Emission of soot particles from the combustion of various fuels in boilers

According to modern estimates, the largest contribution to global warming is made by carbon dioxide, while its share is 60-70%. However, studies of the last decade also indicate a large impact on the planet’s climate of “short-lived climate pollutants”, which mean forcing substances with “lifetimes” in the atmosphere from several days to several years. These pollutants include black carbon. In the Russian Federation, black carbon refers to the substance “carbon (soot)”, which is a dispersed carbon product of incomplete combustion or thermal decomposition of hydrocarbons, consisting of particles of various shapes and having a black color. Soot is a strong carcinogen. It is the 2nd class harmful substance and carried by winds for thousands of kilometres. It has been found that black carbon retains several hundred times more heat than carbon dioxide does. Therefore, reducing black carbon emissions is one of the most important challenges in the fight against climate change. Therefore, the task arises of a comprehensive study of all aspects related to black carbon emissions. Based on this, experimental studies of the emissions of soot particles formed in the combustion chambers of boilers of various capacities and designs were carried out during the combustion of various solid, liquid and gaseous fuels. The structure, size and quantitative composition of soot particles, as well as their constituent elements, were studied using scanning electron microscopy. The research results made it possible to propose a more extended approach for choosing the values of specific soot emissions from the combustion of various fuels in heat generators, which should be used in the inventory of emissions of this pollutant.

Mathematical modeling of a swirling jet in applications to low-emission combustion of low-grade fuels

Abstract. The search for new solutions in the field of energy, preventing negative impact on the environment, is one of the priority tasks for modern society. Natural gas occupies a stable position in the demand of the UES of Russia for fossil fuel. Biogas is a possible alternative fuel from organic waste. Biogas has an increased content of carbon dioxide, which affects the speed of flame propagation, and a lower content of methane, which reduces its heat of combustion. However, the combined combustion of natural gas and biogas, provided that the mixture of fuel and oxidizer is well mixed, can, on the one hand, reduce the maximum adiabatic temperature in the combustion chamber of power boilers at TPPs, and, on the other, increase the stability of biogas combustion. For the combined combustion of natural gas and biogas in operating power boilers, it is necessary to reconstruct the existing burners. For a high-quality reconstruction of burners capable of providing stable and low-toxic combustion of fuel, it is important to have theoretical data on the combustion effect of combustion of combinations of organic fuels on the temperature distribution in the combustion zone and on its maximum value. In this paper, self-similar solutions of the energy equation for axisymmetric motion of a liquid (gas) in a model of a viscous incompressible medium are obtained. Basing on them, a stationary temperature field in swirling jets is constructed. A set of programs based on the ANSYS Fluent software solver has been developed for modeling and researching of thermal and gas-dynamic processes in the combustion chamber. On the basis of the k - ϵ (realizable) turbulence model, the combustion process of a swirling fuel-air mixture is simulated. The results of an analytical and numerical study of the temperature and carbon dioxide distribution in the jet are presented.

Комплексная эффективность применения древесных гранул в энергоустановках

In advanced countries, the dramatic impact of greenhouse gases on the global climate is reduced by replacing fossil fuels with biofuels. This method is being actively encouraged. However, by-products of logging, processing and conversion of wood are classified as difficult to burn fuels due to their high moisture content, low energy density and extremely heterogeneous granulometric composition. A promising direction to increase the energy density and transportability of the timber industry by-products is their granulation. Wood pellet fuel burning in heat-generating plants results in significant increase in their energy and environmental performance. The purpose of the paper is an experimental and calculation study of the energy and environmental performance of 4 MW hot water boilers produced by Polytechnik Luft- und Feuerungstechnik GmbH in the process of burning pine and spruce wood pellets obtained from by-products woodworking. When performing studies, the components of the boiler’s heat balance, gas release, and particulate emissions were determined. Numerical modeling of thermochemical and aerodynamic processes taking place in the boiler combustion chamber was carried out by using the Ansys Fluent three-dimensional simulation software. Together with industrial-operational tests it showed the possibility to reduce the total share of flue gas recirculation into combustion chambers of boiler units to values not exceeding 0.45, in providing an acceptable temperature of combustion products at the combustion chamber outlet and maintaining minimum emissions of carbon and nitrogen monoxides. At the same time, the share of gases fed by recirculation smoke exhausters to the over-bed area of the burner should have higher values than under the reciprocating grates of boilers. Guidelines for comprehensive improvement of wood pellet combustion efficiency in combustion chamber of 4 MW hot water boilers have been developed and implemented. The priorities are: using the air passed through the cooling channels of the setting as secondary air; reducing the rarefaction in the combustion chambers to 30–70 Pa; optimizing the ratio of primary and secondary air, herewith, the share of primary air in the total flow should be 0.26–0.35. Implementation of the developed guidelines allowed to increase the boiler gross efficiency by 0.5–1.8 %, to reduce the aerodynamic resistance of the gas path by 15–20 % and to ensure consistently low emissions of carbon and nitrogen monoxides and soot particles. When designing boiler units for burning wood pellet fuel it is advisable to place heating surfaces in the combustion chamber, included in the circulation circuit of the boiler. This will increase the efficiency and life cycle of the boiler unit.

Multi-objective optimization of CO boiler combustion chamber in the RFCC unit using NSGA II algorithm

In this study, the combustion chamber of a CO steam boiler is multi-objectively optimized (MOO) using computational fluid dynamics (CFD) and non-dominated sorted genetic algorithm II (NSGA II) algorithm. Multi-objective optimization with two input parameters and two objectives are followed. Input parameters are the two inlet air streams into the chamber called primary and secondary air streams. The optimization aims to maximize the outlet gas’s temperature and minimize the chamber’s wall’s temperature. Therefore, these two parameters are considered as the objectives of the optimization. To obtain an adequate number of nodes in the discretized system, a step-wise increase of the mesh is followed and finally, 6.1 million elements are selected. Due to the steam boiler complexity, some simplifications are assumed while it is assured that no remarkable error is introduced. Computations reveal that ignoring radiation at the beginning of the combustion chamber can cause an error as significant as 400 °C. In contrast, for the end of the combustion chamber, where optimization is performed over, an error up to 7.4 °C emerges. NSGA II algorithm is used for multi-objective optimization and the Pareto diagram is extracted and reported. Ultimately, the effect of different fluid intensity of primary and secondary air streams on different parameters like outlet temperature, gas composition in the outlet and the chamber’s wall temperature is presented.

Energy, exergy, exergo-economic and exergo-environmental analyses of solar based hydrogen generation system

The present study focuses on the energy, exergy, exergo-economic, and exergo-environmental analyses of the solar-assisted multi-generation system. The multi-generation system consists of parabolic trough solar collector, regenerative power plant, double-effect absorption chiller system, proton exchange membrane electrolyzer, and multi-stage flash desalination plant. In the regenerative power plant, liquid petroleum gas (LPG) based boiler is implemented. The propane (C3H8) is used as the fuel in the boiler combustion chamber. The thermal and exergetic efficiencies of the power cycle are observed to be 41.08% and 23.26%, respectively. The electrical power of 1.384 MW is produced by the low-pressure turbine. Whereas, the thermal COP and exergetic COP are observed and maintained in the range of 1.28 to 0.22, respectively. The liquid hydrogen is produced by the PEM electrolyzer with the thermal and exergetic efficiencies of 60.83% and 64.65%, respectively. Furthermore, the exergo-economics and exergo-environmental analyses have also been conducted and all the parameters have been analyzed and concluded through graphs and tables.

THE OPTIMIZATION OF CAPACITY BOILER EFFICIENCY 26 TONS/HOURS WITH FUEL ALUMINATION AND STATISTICAL PRODUCT AND SERVICE SOLUTIONS (SPSS) ANALYSIS

The boiler is a steam-producing installation that is used to drive steam turbines as power plants in palm oil mills. It is working to remove the heat generated by fuel into the form of steam containing enthalpy, which is used to drive a steam turbine.This study was conducted for 15 days started from May 27, 2017, until June 15, 2017. The location of the study was conducted at PMKS South Sumatra Province. The average boiler efficiency is 81% with a heating value of 2117.6717 kcal/kg compared to other dates that have a higher heating value but efficiency is below 80%. This shows the success of the boiler's performance is not only determined by the heating value contained in the fuel but also determined by the temperature of the feedwater entering the boiler, the amount of fuel in the boiler and the condition of the fuel in the boiler combustion chamber.

Analysis of deposits from combustion chamber of boiler for dendromass

This article records the degradation of the refractory alumina-silicate lining in a boiler furnace combusting dendromass after ten years of use. The deterioration of refractory alumina material was evaluated from phase and chemical analyses of accretions. The fusion temperatures of accretion were measured with a high-temperature microscope and the results were compared with the solidus (point of first liquid formation) temperature predicted by FactSage 7.3 thermodynamic simulation software. Content of SiO2 (50–65%) in accretions confirms that fine silicate particles of ash adhere to the lining. These silicates react with subliming alkalis from the dendromass and form aggressive eutectic melts on surface of lining at operating temperatures. Increase in operating temperature, inhomogeneity (porosity) and alkali content in accretions are the main factors influencing accretion viscosity, melt convection and lining corrosion. For this reason accretions on the vertical walls lower down are much thicker than on the walls in the upper part and the arch. The Al2O3 concentration is higher in the arch accretions; there the refractory material corrodes intensively. The fusion temperatures of the glassy accretions (measured at the furnace atmosphere: accretion boundary) are around 1150 °C. However, the calculated temperatures of slag formation stated by FactSage are about 150 °C lower, and these correspond to the operating temperature in the upper section of the combusting chamber. The fusion temperatures increase with the Al2O3 content in accretions closer to the lining. The obtained results will be applied to define the requirements for the development of boiler furnace refractories.