Furnace Operation Research Articles

Causal analysis of nitrogen oxides emissions process in coal-fired power plant with LiNGAM

Coal has been an important energy source worldwide; however, it is the largest source of nitrogen oxide (NOx) emissions because the amount of nitrogen in coal is larger than that of other fossil fuels. Precise control of NOx emissions is required in operations of coal-fired power plants from the viewpoint of air pollution control. Although theoretical analyses of NOx generation from a coal-fired power plant have been conducted, it is difficult to precisely predict NOx generation in an actual plant. NOx generation is affected by various factors, such as furnace design and operating conditions, and there are complicated relationships among them. Thus, it is necessary to identify important operating factors that affect NOx generation in actual coal-fired power plants. A linear non-Gaussian acyclic model (LiNGAM) is an exploratory causal analysis method that identifies a causal ordering of variables and their connection strengths without any prior knowledge of causal relationships among variables. In this study, we analyzed real operation data collected from a coal-fired power plant using LiNGAM to identify factors of NOx generation. The causal relationship between process variables and NOx generation was estimated by means of LiNGAM, and the connectional strengths of the variables on NOx generation were derived. The analysis results agreed with previous reports on NOx generation mechanisms, such as combustion air temperature, steam temperature on a specific side of the furnace, and air flow rate of forced draft fans. In addition, we found the steam flow rate and the furnace pressure as new candidate factors of NOx generation through causal analysis using LiNGAM, which heretofore has not been suggested. Our analysis result should contribute to reducing NOx emissions from coal-fired power plants in the future.

Effect of Selective Pellet Loading on Burden Distribution and Blast Furnace Operations

Good permeability of the blast furnace bed is of paramount importance for stable operations of the same and to achieve it, controlled burden distribution is the key. While coke is primarily used to maintain permeability of the furnace bed (with the ferrous burden particles being considerably smaller), global calls for reducing CO2 emissions substantially are pushing blast furnaces to consume lower amounts of the same. Considering this, other burden distribution methods must be explored to maximize permeability of the burden layer. To do so, efforts are made to control pellet dumping in the burden layer in such a way that it occupies more volume in the mid-radial portions away from the walls. Pellets being spherical in shape and having narrower size distributions than sinter offer more inter particle porosity. Discrete element method (DEM) simulations are used to study the effect of the delay in pellet loading time in the ferrous burden (composed of pellets and sinter) on the positioning in the hopper. This positioning is found to subsequently affect the hopper output constitution, which then affects the radial constitution of the ferrous burden layer. Delaying the pellet loading on the ferrous burden is found to delay emptying of the same from the hopper, resulting in more pellets occupying the mid-radial region of ferrous burden layer in the blast furnace. Based on the observations from simulations, trials are taken in blast furnace and relevant parameters are monitored to capture the effect of such a charging practice on operations.

Methodology for assessing the heat potential recovery regime at food industry enterprises

Areas of improving energy saving and the environmental situation in the processing and food industry In Ukraine are relevant, as technologies and equipment by their nature and degree for efficient use of fuel resources are practically achievable for their improvement, especially today. The purpose of the study is to improve the methodology for the optimisation of the mode of reuse of the thermal potential of exhaust process gases in the implementation of a two-stage cooling process. The indicators of process gas emissions with a volume consumption of 0.54 m3 /s and temperature – 1600°C with the parameters of the furnace operation A2-SHBG were used to construct local temperature characteristics. Their construction is carried out based on the heat balance and heat transfer at short surface intervals, considering the parameters of coolant flows. The results were analysed by the Flow Vision software suite under the structure of the graph, according to the laws of thermodynamics. A method for calculating the amount of cold heat agent for reuse in the technological process is proposed. It is established that under the accepted heat exchange conditions, the required amount of atmospheric air with an initial temperature of -300°Ccan be heated to a temperature of +640°C, and with an initial temperature of +300°C, can be heated to +1450°C. Natural gas consumption will change from 20 m3 / h, without preheating atmospheric air, up to 12.7 m3 /h when heating atmospheric air in the heat exchanger at an initial temperature of + 300°C. It is stipulated that when calculating energy resource savings, it is necessary to consider the initial temperature of the cold heat agent when using the heat of exhaust process gases. The proposed method for calculating the optimal heat recovery mode allows calculating changes in the consumption of the primary fuel and energy resource and creating a database for the effective implementation of energy-saving technologies when reusing waste gas heat into production

Numerical Analysis of Factors Affecting the Burden Surface and Porosity Distribution in the Upper Part of the Blast Furnace

A proper burden and porosity distribution of the bed in the upper shaft are important prerequisites for realizing a stable and efficient operation of the ironmaking blast furnace. The discrete element method was used to investigate the effects of the static friction coefficient between burden particles and shaft angle on the burden profile and porosity distribution in the bed formed by charging the burden with a bell-less charging equipment. The results indicate that a large static friction coefficient makes the particles stay closer to the impact point (i.e., where they fall) from the rotating chute. A large mixed region of the burden bed decreases the gas permeability, and an increase in the burden particle roughness will worsen this problem. The burden surface shape becomes flatter with an increase in the shaft angle. These findings explain the effect of particle properties and wall geometry on the inner structure of the burden bed.

Adaptive iterative extended state observer-based data-driven iterative learning model predictive control for semiconductor silicon single crystal batch process

Aiming at the problems of unstable batch control of key crystal quality parameters and susceptibility to batch-to-batch non-repetitive disturbances during repeated operation of single crystal furnaces, this paper proposes a data-driven iterative learning model predictive control method based on an adaptive iterative extended state observer (IESO) for designing melt temperature and crystal diameter learning controllers with disturbance suppression. By applying dynamic linearization techniques and model predictive control strategies along the iterative axis, an ILMPC scheme with disturbance compensation terms using only input and output data of the system is designed. Among them, adaptive IESO is used to estimate the disturbance compensation terms. Then, the theoretical analysis shows that the tracking error of the ILMPC scheme can converge to a bounded range as the number of iterations increases. The experimental results verify the effectiveness of the proposed control method, which not only ensures that the control system has learning ability, but also achieves stable and accurate control of crystal quality parameters.

Phase Equilibria Studies in the CaO-MgO-Al2O3-SiO2 System with Al2O3/SiO2 Weight Ratio of 0.4

With the raw materials for ironmaking becoming increasingly complex, more accurate phase equilibrium information on the slag is needed to refine the blast furnace operation to reduce the energy cost and CO2 emissions. CaO-SiO2-Al2O3-MgO is a basic system of ironmaking slag in which CaO and MgO mainly come from the flux, SiO2 and Al2O3 are mainly from raw materials. The effect of flux additions on the phase equilibrium of the slag can be described by a pseudo-ternary system CaO-MgO-(Al2O3+SiO2) at a fixed Al2O3/SiO2 ratio of 0.4. Liquidus temperatures and solid solutions in the CaO-MgO-Al2O3-SiO2 system with Al2O3/SiO2 weight ratio of 0.4 have been experimentally determined using high temperature equilibration and quenching techniques followed by electron probe microanalysis. Dicalcium silicate (Ca2SiO4), cordierite (2MgO·2Al2O3·5SiO2), spinel (MgO·Al2O3), merwinite (3CaO·MgO·2SiO2), anorthite (CaO·Al2O3·2SiO2), mullite (Al2O3·SiO2), periclase (MgO), melilite (2CaO·MgO·2SiO2-2CaO·Al2O3·SiO2) and forsterite (Mg2SiO4) are the major primary phases in the composition range investigated. A series of pseudo-binary phase diagrams have been constructed to demonstrate the application of the phase diagrams on blast furnace operation. Composition of the solid solutions corresponding to the liquidus have been accurately measured and will be used for the development of the thermodynamic database.

Investigation on Segregation Granulation by Fuel and Flux in Coating

The metallurgical property of sinter is an important factor affecting the smooth operation of blast furnaces (BF), because it has a great impact on the permeability of BF and solid fuel rate. In order to promote the combustion of solid fuel and the mineralization of flux in sintering process, and eventually improve the strength of sintered ore, a series of investigation on segregation granulation by fuel and flux in coating were carried out, including the sinter pot experiments, the morphology analysis, and the discussion combine with phase diagram. The experimental results show that, (1) as the CaO increased from 0% to 40% and coke breeze increased from 0% to 100%, the sintering indices were improved, the tumble strength of sinter increased from 65.8% to 68.4%, the rate of qualified products increased from 77.4% to 81.0%, and the micro-strength of sinter increased from 68.7% to 75.9%. (2) There are three reasons for the high strength of sinter by segregation granulation of fuel and flux in coating, (a) the complete combustion of solid fuel and release the heat, (b) the effective absorb heat and mineralization of flux, and (c) the improvement of fluidity of bonding phase. The outcomes of the present work may provide a new method to improve the strength of sintered ore and give some reference for better understanding segregation granulation process and using it in actual operation.

Advantages and risks of using ore-coal briquettes in blast furnaces

Reducing carbon consumption, and, consequently, CO2 emissions during iron smelting in blast furnaces is a priority for improving the technology of blast furnace smelting. In the literature, the question of the influence of the development of direct reduction of iron on the consumption of carbon as a source of reducing gas and a source of heat has been considered. In this case, the development of direct reduction in the lower zone of the furnace at temperatures above 900 °C is considered. However, direct (solid-phase) reduction can be implemented in the upper zone of a blast furnace when using ore-coal briquettes in the charge. It is shown that the solid-phase reduction reactions can proceed at temperatures above 700 °C in the upper zone of a blast furnace during the reduction of Fe3O4 and FeO. At the same time, the apparent heat capacity of the charge increases and the temperature of the top gas decreases, which is confirmed by data on the operation of blast furnaces of NLMK PJSC, which use ore-coal briquettes. The raw materials for the production of briquettes are iron ore concentrate, sludge, blast furnace dust, aspiration dust. A bentonite and a ce-ment are used as a binder. The briquettes contain 40‒42% iron and 10‒15% carbon. The theoretical analysis and statistical processing of data on the operation of blast furnaces led to the conclusion that the solid-phase reduction of iron oxides actively proceeds at temperatures below 900 °C. The results of experimental heats showed the use of briquettes allows to reduce the specific consumption of coke and the total carbon consumption of fuel. The prospects for the use of the briquettes are associated with an increase in their mechanical properties. The use of ore coal briquettes obtained from a concentrate with an iron content of 65‒68% will reduce the rate of fuel carbon and CO2 emissions.

Substitution of Natural Gas by Biomethane: Operational Aspects in Industrial Equipment

Global gas markets are changing as natural gas (NG) is replaced by biomethane. Biomethane is produced by upgrading biogas, which can have a molar concentration of methane to over 98%. This renewable energy has been injected into the pipeline networks of NG, which offers the possibility to increase its usage in industrial and residential applications. However, the expectation of the increase in biomethane proportion on the NG grids could increase the fluctuations on the composition of the NG–biomethane mixture in amplitude and frequency. In this context, the injection of biomethane into the existing network of NG raises a discussion about the extent to which variations in gas quality will occur and what permissible limits should exist, as variations in combustion characteristics can affect the operation of the combustion processes, with consequences for consumers, distributors and gas producers. This study describes a gas quality analysis with regard to the use of biomethane in industrial equipment, mixed or not mixed with NG, taking into account the indicators for gas interchangeability and provides a discussion on the necessary gas quality level to be achieved or maintained for efficient combustion in equipment originally designed to operate with NG. NG and biomethane real data collected for 92 consecutive days in 2022 and provided by two different companies in Brazil were used for this study. It is shown that the maximum deviation of the Wobbe Index (WI) of 5%, which is allowed for industrial plants, does not work for the operation of furnaces at temperatures of 1200 °C or more. In addition, it is shown that the WI, as defined in relation to the calorific value of the fuel, may allow inappropriate substitution of fuel gases, which is likely to reduce the range of blending of biomethane in NG pipelines. The results can be assessed to analyze how the addition of biomethane to NG grids will impact the WI and the equipment operation parameters such as the air-to-gas ratio, products-to-gas ratio, adiabatic flame temperature and furnace temperature.

Impact of Biocoke Utilization on the Cupola Furnace Operation and its Effect of CO<sub>2</sub> Reduction

Impact of Biocoke Utilization on the Cupola Furnace Operation and its Effect of CO<sub>2</sub> Reduction

Mathematical modeling of zinc concentrate roasting in a fluidized bed

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.

Assessment of changes in productivity and limitations in forcing movement when increasing the volume of blast furnaces

The selection of the useful volume of new or reconstructed blast furnaces is an urgent task for both manufacturers and designers; therefore, the assessment of the technological capabilities of furnaces of different volumes has always been of interest from both a practical and a theoretical point of view. The purpose of the presented work is the selection of the most representative indicators, with the help of which a comparative assessment of the operation of furnaces of different volumes is possible, the evaluation of the operation of furnaces in the conditions of planned and market economies, as well as an attempt to determine and classify the factors limiting the forced operation of furnaces of increased volume. It is shown that the use of indicators calculated per unit area furnace is not appropriate, since area furnace is not the main size furnace. The main size is full volume furnace, which determines design unit and amount of capital costs for its construction. Specific productivity indicators calculated per unit volume furnace similarly depend on the height furnace and adequately reflect performance of furnaces of different volumes. The indisputable advantage of compact blast furnaces with a useful volume < 1500 m3 in comparison with furnaces of larger volumes is shown, which indicates imperfection of a simplified approach to evaluating performance of furnaces based on the concepts of balance and gas dynamic components, since it is difficult to take into account all the components when determining these components influencing factors. Factors limiting process intensification in blast furnaces of medium and large volumes have been established and classified. The main external factors are the quality characteristics of coke, iron ore materials and blowing, more specifically, hot strength of coke, richness of raw materials in iron and the ability of air blowers to provide blowing with required degree of compression. The main structural solutions to overcome significant limitations in operation of furnaces with a useful volume > 1500 m3 are a rational profile, ratio of output cross-section of air nozzles and cross-section furnace, as well as the use of coneless loading devices.

Comparison of the chemical health risk assessment of exposure to metal fumes for the furnace operator of a foundry industry using quantitative and semi-quantitative methods

Heavy metals have several adverse effects on the workers' bodies due to their accumulation in the vital organs. Besides that, the current study aimed to assess the health risk of exposure to metal fumes for furnace operators working in a foundry industry based on the three different methods. The current sectional descriptive-analytical research conducted on a foundry industry in Isfahan (Iran) in 2022. Three common methods currently available, including the Semi-Quantitative Risk Assessment Method (SQRCA) and two methods provided based on the US-EPA provided technique, were used in this study. At first, the extent of people's exposure to metal fumes of Fe, Ni, Cr, and Mn was measured. Then, the chemical risk assessment of exposure to these metals' fumes was done using the three methods, and their results were compared. The SPSS Ver.25 has been used for data analysis and comparison in the current study. Results indicated that the furnace operator's exposure to all four metals was above the allowed limit of occupational exposure. The chemical risk assessment results also showed that in the first method (US-EPA-based), the risk of exposure for all workers was acceptable, while in the second method (SQCRA), the risk level of a majority of workers was medium, and in the third method (US-EPA-based), the risk level of a majority of workers was not acceptable. Comparing the methods showed that average risk scores in the first and second methods were significant compared to the exposure to fumes with equivalent concentration (Pvalue<0.05). The average score of carcinogenicity risk in method 3 was significant compared to the concentration of chromium and nickel (P-value < 0.05), but it was not significant for iron and manganese and the non-carcinogenic risk of chromium and nickel. Chemical exposure risk level for the furnace operator was approximately moderate in all three methods. In terms of complexity and information required to implement the method, all three methods were almost the same, with the difference that the results of the first method cannot be generalized to other people who have the same job conditions because individual information such as a person's weight is used to calculate its score.

Удосконалення технологічних вимог до розподілу шихтових матеріалів та газового потоку при роботі доменних печей з низьким вмістом кремнію у чавуні та оцінка можливості їх реалізації на сучасних доменних печах

Reducing the silicon content in pig iron is one of the most effective ways to reduce fuel and reductant consumption in the blast furnace process. The challenges of smelting pig iron with low silicon content are associated with high ore burden and low solid fuel consumption, resulting in a reduction in the thickness of "coke windows" with a corresponding deterioration of the gas permeability of the burden column and a decrease in the stability of the melt descent. Additionally, there is a decrease in the thermal level of the cohesive zone, shifting its boundaries upwards in the furnace and increasing its overall size. Moreover, reducing the amount of solid fuel in the burden and increasing the requirements for the quality and stability of the characteristics of iron ore materials can lead to a reduction in the heat reserve in the upper part of the furnace. Research Objective: To improve technological requirements for the distribution of burden materials and gas flow as fundamental principles that determine the parameters of the charging regime of the blast furnace under specific conditions, taking into account the peculiarities and technological constraints of blast smelting with low silicon content in pig iron. The study involves the consolidation of results from analytical and laboratory research, as well as the industrial experience of smelting low-silicon pig iron under production conditions. Technological requirements have been developed for the distribution of ore burden, ensuring stable axial movement of the blast furnace under specific melting conditions, the distribution of iron ore components of the burden, based on the tasks of ensuring the stability of the sinter layer and preserving the lining, as well as the distribution of various substitutes for iron ore burden materials and coke, taking into account their properties and technological characteristics. Recommended parameters for the "soft" preventive flushing of blast furnaces are provided to ensure the necessary gas permeability of the burden column, the diffusion capacity of the coke layer, and the support of a stable axial distribution of the gas flow. An assessment of the possibilities of implementing improved technological requirements for the distribution of burden and gas flow under conditions of smelting low-silicon pig iron in modern blast furnaces has been carried out.

STUDY ON VIBRATION AND THERMAL EXPANSION OF HEATING FURNACE MANIFOLD BASED ON FLUID-STRUCTURE INTERACTION METHOD

In the petrochemical industry, the manifolds are usually adopted as the distributor of the heating furnace. The structure of the manifold plays a crucial role in the safe operation of the heating furnace. For the straight tube structure and fishbone structure of the manifold, thermal expansion calculation was carried out in this paper. The expansion amount of each branch pipe was obtained, and the maximum expansion amount of the branch pipe was 91.8&amp;#37; of the reserved size. The accuracy of the design of the branch pipe wall clearance allowance was verified. Numerical simulations of the fluid-structure interaction were carried out for both structures, which showed that the two structures have similar deformation and frequency in terms of overall structural vibration. However, in the branch vibration, the stress and vibration frequency of the fishbone branch increase by 12.6&amp;#37; and 25.3&amp;#37;, respectively, compared to the straight tube branch, which is caused by the presence of large vortices in the branch of the fishbone structure. Finally, modal analyses were performed for both structures, and the results can be used to estimate whether the vibration frequencies of the two structures avoid the natural frequencies.

ВЛИЯНИЕ ИНТЕНСИВНОСТИ КРУТКИ ВОЗДУХА В ВИХРЕВЫХ ГОРЕЛКАХ НА ВЫДЕЛЕНИЕ ОКСИДОВ АЗОТА В ПРОМЫШЛЕННЫХ ТРУБЧАТЫХ ПЕЧАХ

An important task in the design and operation of industrial furnaces is to reduce the formation of harmful substances, in particular, nitrogen oxides (NOx), directly at the source of their occurrence. One of the promising methods of reducing the concentration of NOx in the gas emissions of furnaces is the use of vortex burners with a twist of the flow, providing better mixing of combustion products, thereby reducing the maximum local temperatures in the furnace and equalizing the temperatures over the working volume. However, the available information on the effect of vortex formation on the intensity of nitrogen oxides release is extremely contradictory – depending on the design of the burners and the furnace, the twist of the flow can both increase and decrease the formation of nitrogen oxides. Moreover, single burners have been studied at least in some way from the point of view of NOx release, but their interaction with each other in large-volume furnaces has not been practically investigated and requires additional study. By numerical experiments conducted on the basis of the mathematical model developed by us, it is shown that the smallest release of nitrogen oxides is ensured by the use of burners with a twist of the air flow (oxidizer), as well as their combination with two-stage combustion when the burners are located in the same horizontal plane. It is shown that the combined use of these two methods reduces the release of nitrogen oxides in the furnace by more than a factor of ten.

Influence of the temperature fluctuations on the flame temperature and radiative heat exchange inside a pulverized coal-fired furnace

In this paper, influence of the temperature fluctuations, (as a version of turbulence-radiation interaction), on the flame temperature and radiative heat exchange inside the pulverized coal-fired furnace was investigated. The radiative heat exchange was solved by the Hottel zonal model. The influence of the temperature fluctuation was studied for three values of the extinction coefficient of the flame: 0.3 m?1, 1.0 m?1, and 2.0 m?1. The investigation was conducted for the relative temperature fluctuations obtained by solving the transport equation for the temperature variance, and for four constant values of the relative temperature fluctuations (0.0, 0.1, 0.15, and 0.2). The maximal values of the mean temperature fluctuations and relative temperature fluctuations were obtained in the region close to the burners. The decrease of the flame temperature of about 100 K was obtained in the hottest region, for every extinction coefficient. An increase in the mean wall flux was found to be on the order of several percents, compared to the case without the temperature fluctuations. When the temperature variance was calculated, the mean relative temperature fluctuations were approximately 15%, for every extinction coefficient. The mean wall fluxes increased and flame temperature at the furnace exit plane decreased with the increase in the relative temperature fluctuations. The selected indicators of the furnace operation, such as the mean wall flux and mean flame temperature at the furnace exit plane, obtained for the calculated temperature variance, were close to the values predicted for the constant relative temperature fluctuation of 15%.

The use of numerical simulation to determine the coal combustion efficiency in the A-USC boiler

In this paper, numerical simulation of coal combustion in the invert furnace of a boiler for a 500 MW power unit designed to operate on advanced ultra-supercritical steam parameters (A-USC) is performed. The use of A-USC technology makes it possible to reduce fuel costs for electricity production compared to steam turbine units of previous generations. Also it influences to reduce the level of emissions of harmful substances into the atmosphere. Modeling of the invert furnace at the nominal boiler load was carried out for the developed direct-flow burners and nozzles arrangement of burning coal. After numerical simulation the results were obtained and made it possible to analyze the furnace aerodynamics and the temperature distribution inside the furnace volume. The calculation of the indicators of efficiency and environmental friendliness was carried out and their values appeared smaller than regulatory permissions, which allows us to recommend the developed burners arrangement scheme for its use in invert furnaces. The furnace operation simulation at reduced loads of 70% and 50% was carried out and the results showed the reliability of the developed combustion scheme.

Determination of the sootblower activation moment for biomass co-firing in a pulverized coal furnace

The pulverized coal-fired furnaces are expected to use co-firing with biomass for environmental reasons. Although the non-uniform ash deposits are formed on the furnace walls, the uniform deposits could be used for the analysis of the furnace operation. The objective of this investigation was determination of the uniform deposit thickness, used as a criterion for prediction of the sootblower activation moment in coal-biomass co-firing. The investigation comprised numerical simulations for uniform and non-uniform deposits to find the relative differences for the selected variables that were important for the sootblower activation: the mean wall fluxes and flame temperatures. The local thicknesses of the non-uniform deposits were determined by the gamma distribution for several mean and standard deviation values using the inversion method. The thicknesses of the uniform deposits were considered among the measures of central tendency: mode, mean, and median, of the non-uniform deposits. The mean was expected to provide the smallest relative differences, while the mode was excluded from further consideration after analysis of its values. The median was found to be better choice than the mean, as it provided smaller relative differences of the selected variables for the thick deposits, which were important for the sootblower activation. The method based on comparison of the uniform deposits for coal firing and those for the co-firing with biomass was proposed for the prediction of the sootblower activation moment. The method can be used for the selection of the operational regimes for coal-biomass co-firing.

Specific features of the use of pulverized coal fuel in combined chemical processing

Expanding the applications of combined thermochemical processing of mineral raw materials is one of the priority development areas in the non-ferrous metals industry. In particular, combined processes involving reduction roasting and the Waelz process are considered very promising, for example, for additional recovery of non-ferrous and accessory metals from metallurgical cakes. The first chemical stage of these reduction processes is the conversion of carbon fuel into carbon monoxide and carbon dioxide in the presence of oxygen and water vapor. The urgency of a detailed study of this stage is due, among other reasons, to the many problems related to CO2 emissions into the environment. Carbon dioxide emissions into the atmosphere are largely associated with the operation of furnace units that consume a significant amount of carbon-containing utility products. Operation of tubular rotary furnaces involves high temperatures, achieved by burning various types of fuels. This article discusses the process of burning pulverized coal fuel that results in an incomplete burnout of coal particles. Subsequent exposure of the unburned solid phase to the combustion products leads to the formation of a multicomponent heterogeneous system that maintains the synthesis reactions for CO and H2. These reactions, occurring at high temperatures, change the equilibrium composition of the combustion products dramatically. An algorithm is proposed for calculating the equilibrium composition by solving a system of nonlinear equations. The calculation was made by the iterative Newton&rsquo;s method at a constant temperature, assumed on the basis of the calculated theoretical combustion temperature of the fuel of a given composition.