Furnace Chamber Research Articles

Utilization of ceramic waste by using it as special concrete aggregate

In the article is presented the method ofutilization of ceramic waste by using it as special concrete aggregate for special high temperature resistant concentrates. The research was performed on six empirically designed concrete mixtures of three on aluminous cement with simultaneous aerification with using air entraining admixture respectively at 0, 5 and 10%. In order to compare the results, three Portland cement concrete mixes were prepared which had exactly the same aerification of the mixture. All types of samples were made using recyclable aggregates of sanitary ceramics selected and crushed to 0-4 mm and 4-8 mm. This particular type of aggregate, as proved in previous authors’ workshowed very favorable features in terms of the influence for thermal loads. Selected samples were subjected to a thermal treatment according to the standard curve “temperature-time” for 120 minutes until the furnace chamber temperature reached approximately 1050°C. With interative concrete mixture method design, assuming that the mixture substrates were limited to the commonly used cements and the appropriate amount of air entraining admixture, there were received tight concrete with high strength parameters, which also demonstrates resistance explosive concrete particles’ chipping off under conditions of high temperatures.

Calculation of temperature and velocity fields in the furnace chambers of tube ovens

This paper presents the results of calculations of velocity and temperature fields in the radiation chamber of an energy-intensive technological tubular oven during the combustion of methane in air using acoustic burners of floor flame. The calculation method is based on the joint numerical solution of difference analogs of three-dimensional equations of energy transfer by radiation, convection and turbulent thermal conductivity, the movement of flue gases and the methane combustion model in the air. The radiation selectivity of flue gases is taken into account using a six-band model. The paper contains a diagram showing the organization of a three-dimensional modelling of acoustic burners. It also represents the isotherms of combustion products, the lines of the velocity vectors in the radiation chamber, distributions of surface densities of heat fluxes to the heating surface.

Properties of B-pillar made of aluminium 7075 in warm forming process

Abstract This paper presents the properties of warm forming of a B-pillar from 7075 aluminum alloy in state T6. Based on preliminary mathematical modeling, it was determined that the greatest strains and risk of aluminum cracking occur in the foot of B-pillar, therefore the forming process was simplified and conducted only for this part. The most important issue was to select the proper forming temperature and heating time, so as to preserve state T6 of the aluminum. Conducted tests demonstrated that the best mechanical properties without cracking were obtained for component place in a chamber furnace preheated to temperature 350°C. After approx. 5-6.5 minutes, it reached a temperature of 240°C.

WET BURNING – THE MODERN TREND IN ENVIRONMENTAL BENIGN FUEL COMBUSTION AND IN SOLUTION TO THE PROBLEM OF SUSTAINABLE DEVELOPMENT OF THE POWER GENERATION

The article considers the role and place of water and water vapor in combustion processes with the purpose of reduction the effluents of nitrogen oxides and carbon oxide. We have carried out the complex of theoretical and computational researches on reduction of harmful nitrogen and carbon oxides by gas fuel combustion in dependence on humidity of atmospheric air by two approaches: CFD modeling with attraction of DRM 19 chemical kinetics mechanism of combustion for 19 components along with Bowman’s mechanism used as “postprocessor” to determine the [NO] concentration; different thermodynamic models of predicting the nitrogen oxides NO formation. The numerical simulation of the transport processes for momentum, mass and heat being solved simultaneously in the united equations’ system with the chemical kinetics equations in frame of GRI methane combustion mechanism and NO formation calculated afterwards as “postprocessor” allow calculating the absolute actual [CO] and [NO] concentrations in dependence on combustion operative conditions and on design of furnace facilities. Prediction in frame of thermodynamic equilibrium state for combustion products ensures only evaluation of the relative value of [NO] concentration by wet combustion the gas with humid air regarding that in case of dry air – oxidant. We have developed the methodology and have revealed the results of numerical simulation of impact of the relative humidity of atmospheric air on harmful gases formation. Range of relative air humidity under calculations of atmospheric air under impact on [NO] and [CO] concentrations at the furnace chamber exit makes φ = 0 – 100%. The results of CFD modeling have been verified both by author’s experimental data and due comparing with the trends stated in world literature. We have carried out the complex of the experimental investigations regarding atmospheric air humidification impact on flame structure and environmental characteristics at natural gas combustion with premixed flame formation in open air. The article also proposes the methodology for evaluation of the nitrogen oxides formation in dependence on moisture content of burning mixture. The results of measurements have been used for verification the calculation data. Coincidence of relative change the NO (NOx) yield due humidification the combustion air revealed by means of CFD prediction has confirmed the qualitative and the quantitative correspondence of physical and chemical kinetics mechanisms and the CFD modeling procedures with the processes to be studied. A sharp, more than an order of reduction in NO emissions and simultaneously approximately a two-fold decrease in the CO concentration during combustion of the methane-air mixture under conditions of humidification of the combustion air to a saturation state at a temperature of 325 K.

Numerical studies on heat coupling and configuration optimization in an industrial hydrogen production reformer

Steam methane reforming furnaces are the most important devices in the hydrogen production industry. The highly endothermic reaction system requires reaction tubes in the furnace to have a large heat transfer area and to be operated under high temperature and pressure conditions. In order to enhance heat transfer efficiency and protect reaction tubes, the controlling and optimization of the furnace structure have increasingly received more and more research attention. As known from the furnace structure, it is essential to couple the exothermic combustion with the endothermic reforming reactions due to the highly interactive nature of the two processes. Thus, in this paper, the combustion process in the furnace was numerically studied by using computational fluid dynamics (CFD) to model the combustion chamber, coupled with methane steam reforming reaction inside the reaction tubes, defined by a plug flow model. A set of combustion models were compared for the furnace chamber and a plug flow reaction model was employed for reforming reaction tubes, and then a heat coupling process was established. The predicted flue gas temperature distribution showed that the heat transfer in the furnace was not uniform, resulting in hot spots and heat losses on the tube wall. Therefore, structure optimization schemes were proposed. Optimization on arrangements of the tubes and the nozzles promoted the uniform distribution of flue-gas temperature and then improved heat transfer efficiency, thereby enhancing performance of the steam reforming process.

Experimental Study on the Bubble Formation Mechanism during the Sintering of Coal and Biomass Ash Blends

This paper presents an experimental study on bubble formation in the process of sintering of Zhundong coal and corn stalk (CS) ash blends in a horizontal chamber furnace. The effect of the blend ra...

A new method of manganese alloys obtaining

High cost of the ferromanganese production by traditional methods resulted in searching of new technologies for its production. The main objective of the study was to establish the technological parameters of a new process for the ferromanganese production by using ITmk3 process elements in laboratory conditions. The studies were carried out in the “Nabertherm” chamber furnace, which allows for simulate the temperature and time parameters of ITmk3 process elements in a rotary hearth furnace.The charge for ferromanganese obtaining consisted of manganese ore from the Zhayremsk deposit (Kazakhstan) and non-scarce coal, the consumption of which provided close to stoichiometric one in carbon for the direct reduction of manganese and iron from the correspondent oxides. The composition of the ore gangue and coalash provided a mixture with a slag melting point below 1400 °C.The maximum yield of ferroalloy and the conversion of manganese into the ferroalloy from the burden was achieved at a temperature and duration of thermal treatment of 1500 °C and 10 min, respectively. Information obtained during the study may be used for large-scale testing in a commercially size rotary hearth furnace.

Experimental study on seismic performance of post-fire reinforced concrete frames

To investigate the post-fire seismic behaviour of reinforced concrete (RC) frames with different column-to-beam bending capacity ratios, four specimens were fabricated, which included a strong-beam-weak-column frame and a strong-column-weak-beam frame either under room temperature or after being exposed to fire. The fire test was conducted in a furnace chamber, followed by quasi-static tests under a low-frequency cyclic load. The crack patterns, hysteretic loops, plastic hinges, and failure modes were investigated in the loading process. The influence of two factors, i.e., the fire exposure and the column-to-beam bending capacity ratio, on the mechanical performance, ductility, stiffness degradation, and energy dissipation was compared and analysed. The experimental results indicated that the ultimate bearing capacity, the stiffness, the ductility factor, and the energy dissipation capacity of the RC frames decreased after fire exposure. The bearing capacity of the strong-beam-weak-column frame decreased even more seriously. Although the yielding displacements of the post-fire frames increased, their ultimate displacements decreased. In addition, the strong-column-weak-beam frame under room temperature failed in the form of beam-end plastic hinging, while after being exposed to fire, the failure mode changed to shear-bond failure in column.

Improvement of pellet fuel bed combustion technology in low power boilers

This paper describes different ways of efficiency improvement in pellet fuel bed combustion and proposes methods of pellet fuel combustion, ensuring high environmental and energy performance. The constriction in the form of a convergent-divergent passage in the furnace chamber with simultaneous delivery of the secondary air at the point of maximum dispersal of the exhaust gases has reduced unburned combustible losses by 39%. At the same time, the constriction has reduced heat transfer surface area and residence time of hot gases in the furnace chamber, which increased the exhaust gases temperature at the combustion chamber outlet by 98°C. Ansys CFX software package was actively used for numerical simulation during the development of innovative furnace chamber design. To verify simulation results, the firing test bench was designed.

OPTIMIZATION OF HEATING OPERATION CONTROL IN CHAMBER-TYPE THERMAL FURNACE

Using local systems of automatic control of temperature and surplus pressure of heating in the working volume of flaming thermal furnace of chamber type, settings, as a rule, are selected separately without the account of their interconnection. At the same time in control of expense of fuel and air not only temperature but also pressure changes in the working chamber of furnace, that, in turn, is accompanied by change of gaseous exchange with a medium and renders substantial influence temperature in a working chamber. All this is accompanied by substantial excessive consumption of gaseous fuel, and, as a result, by the rise of costs of metal heat treatment. Using heating chart with the constant volume of products of burning in the furnaces of such type, the control of its heat power is in combining charges of different components of gaseous fuel at condition of providing of the given temperature in the working volume. According to the principle of Bellman dynamic programming, optimization of control for the cycle of metal heat treatment was provided by choice of the applied fuel which is optimal on a cost composition for every period of quantum. The present cost of fuel serves as the linear function of middle charges of its separate components in periods of quantum and finding of its minimum value for every discrete moment of time, presented as a decision of task of the linear programming. The determination algorithm for optimal values of charges of gaseous fuel separate components was worked out, as well as for the expense of surplus air, used as controlling influences for the automatic systems of adjusting of temperature and surplus pressure of heating medium in the working volume of furnaces. The functional cart of automatic control system is provided, which implementation allows not only optimization of heating technology by cost of separate fuel components, but also provision of the control autonomy of temperature and surplus pressure of heating medium in the working chamber of furnaces of chamber type by means of self-adjustment. In real-time control process is executed with optimization of cost of separate components of fuel self-adjustment of the system.

Effect of Carburization Parameters on Hardness of Carburized Steel Using MOORA Approach

In this research, (MOORA) approach based– Taguchi design was used to convert the multi-performance problem into a single-performance problem for nine experiments which built (Taguchi (L9) orthogonal array) for carburization operation. The main variables that had a great effect on carburizing operation are carburization temperature (oC), carburization time (hrs.) and tempering temperature (oC). This study was also focused on calculating the amount of carbon penetration, the value of hardness and optimal values obtained during the optimization by Taguchi approach and MOORA method for multiple parameters. In this study, the carburization process was done in temperature between (850 to 950 ᵒC) for 2 to 6 hours. Quenching was done for the specimens after heat treatments in furnace chamber by using different quench solutions, water, salt and polyvinyl alcohol. Analysis of variances - (ANOVA) were performed for nine experiments in order to optimize the problem that was associated with multiple criteria (parameter) to achieve maximum hardness and depth penetration. The program results showed that the optimum conditions are carburization temperature (950 oC), carburization time (2 hrs.), tempering temperature (200oC), tempering time (10 hrs.), and activator (10 wt. %). Furthermore, the best quenching media was the polyvinyl alcohol.

Effect of Carburization Parameters on Hardness of Carburized Steel Using MOORA Approach

In this research, (MOORA) approach based– Taguchi design was used to convert the multi-performance problem into a single-performance problem for nine experiments which built (Taguchi (L9) orthogonal array) for carburization operation. The main variables that had a great effect on carburizing operation are carburization temperature (oC), carburization time (hrs.) and tempering temperature (oC). This study was also focused on calculating the amount of carbon penetration, the value of hardness and optimal values obtained during the optimization by Taguchi approach and MOORA method for multiple parameters. In this study, the carburization process was done in temperature between (850 to 950 ᵒC) for 2 to 6 hours. Quenching was done for the specimens after heat treatments in furnace chamber by using different quench solutions, water, salt and polyvinyl alcohol. Analysis of variances - (ANOVA) were performed for nine experiments in order to optimize the problem that was associated with multiple criteria (parameter) to achieve maximum hardness and depth penetration. The program results showed that the optimum conditions are carburization temperature (950 oC), carburization time (2 hrs.), tempering temperature (200oC), tempering time (10 hrs.), and activator (10 wt. %). Furthermore, the best quenching media was the polyvinyl alcohol.

Effect of Carburization Parameters on Hardness of Carburized Steel Using MOORA Approach

In this research, (MOORA) approach based– Taguchi design was used to convert the multi-performance problem into a single-performance problem for nine experiments which built (Taguchi (L9) orthogonal array) for carburization operation. The main variables that had a great effect on carburizing operation are carburization temperature (oC), carburization time (hrs.) and tempering temperature (oC). This study was also focused on calculating the amount of carbon penetration, the value of hardness and optimal values obtained during the optimization by Taguchi approach and MOORA method for multiple parameters. In this study, the carburization process was done in temperature between (850 to 950 ᵒC) for 2 to 6 hours. Quenching was done for the specimens after heat treatments in furnace chamber by using different quench solutions, water, salt and polyvinyl alcohol. Analysis of variances - (ANOVA) were performed for nine experiments in order to optimize the problem that was associated with multiple criteria (parameter) to achieve maximum hardness and depth penetration. The program results showed that the optimum conditions are carburization temperature (950 oC), carburization time (2 hrs.), tempering temperature (200oC), tempering time (10 hrs.), and activator (10 wt. %). Furthermore, the best quenching media was the polyvinyl alcohol.

Coal Chemical Wastewater Treatment Process Based on Computer Simulation Technology

With a focus on coal chemical wastewater treatment, this study establishes a numerical simulation algorithm based on JAVA language for microwave-assisted coal chemical wastewater treatment, compares the testing results with the numerical simulation results, verifies the validity of the proposed numerical calculation method, and analyzes the effects of different pH values and H2O2 amount on coal chemical wastewater treatment by numerical simulation. In addition, the study analyzes the working principle of microwave-assisted coal chemical wastewater processor under multi-coupling action by calculating the electric field distribution, average power density, temperature field and concentration field in the furnace chamber. When pH = 3 and pH = 4, the removal rate of PNP in wastewater is the highest, reaching above 92.6%. When pH = 3, the reaction rate reaches 0.213/min. When H2O2 amount increases, both the removal efficiency and reaction rate of PNP increase obviously. The highest removal rate of PNP can amount to 93% and the highest reaction rate is 0.211/min. Therefore, the optimal pH value of wastewater treatment is determined to be 3, and the optimal H2O2 amount is 350mg/L.

Design and Fabrication of Crucible Furnaces by using Black Smithy Setup

The main aim was, to design Pit Furnace from the setup of black smithy. As the Smithy setup was not in use so it is converted into Pit Furnace setup. The purpose of using Pit Furnace is to melt nonferrous material. The Nonferrous materials such as Aluminum, Aluminum alloy, Copper, Brass, etc. The Aluminum has less melting point (680ᵒ C, 1218ᵒF) and cheaper than other. The thermal efficiency of furnace is 13.72% which is obtained by melting 2 kg of Aluminum for 75 minutes. Normally thermal of pit furnace is between 4-19%. The blower is used to supply the air into the furnace chamber to burn the coal. For melting the Aluminum, Crucible should sustain higher temperature so Graphite Crucible is used. This Crucible has thinner wall and have more refractory properties.

Design and Fabrication of Crucible Furnaces by using Black Smithy Setup

The main aim was, to design Pit Furnace from the setup of black smithy. As the Smithy setup was not in use so it is converted into Pit Furnace setup. The purpose of using Pit Furnace is to melt nonferrous material. The Nonferrous materials such as Aluminum, Aluminum alloy, Copper, Brass, etc. The Aluminum has less melting point (680ᵒ C, 1218ᵒF) and cheaper than other. The thermal efficiency of furnace is 13.72% which is obtained by melting 2 kg of Aluminum for 75 minutes. Normally thermal of pit furnace is between 4-19%. The blower is used to supply the air into the furnace chamber to burn the coal. For melting the Aluminum, Crucible should sustain higher temperature so Graphite Crucible is used. This Crucible has thinner wall and have more refractory properties.

Optimal Thermal Control of a Chamber Furnace

When using local automatic control systems, the temperature and excess pressure of the hot gas in a chamber furnace are generally chosen independently, without regard for their interrelationships. At the same time, regulation of the fuel and air consumption involves changes in not only the temperature but also the pressure in the furnace chamber. That, in turn, changes the gas transfer with the surroundings and has a considerable influence on the temperature in the working chamber. As a result, the combustion of the gaseous fuel is excessive, and consequently furnace operating costs are increased unnecessarily. With constant volume of combustion products in such furnaces, control of the thermal power entails combining different components of the gaseous fuel with specified temperature in the working volume. On the basis of Bellman dynamic programming, the control of the heat-treatment cycle in the furnace may be optimized by selecting the optimal fuel composition (in terms of fuel cost) for each quantization period. The fuel cost is regarded as a linear function of the mean consumption of the individual fuel components in the quantization periods. Its minimum value for each instant is found by linear programming. An algorithm is developed for determining the optimal consumption of individual components of the gaseous fuel and also the consumption of the excess air, which is used in automatic control of the temperature and excess pressure of the hot gas within the working volume of the furnace. The proposed automatic control system not only permits optimization of the heating process in terms of the cost of the individual fuel components but also ensures autonomous control of the temperature and excess pressure of the hot gas in the working volume of the chamber furnace. With real-time control and cost optimization of the fuel components, the system is self-adjusting.

Дослідження впливу розрідження на процес нагріву багатокамерної печі випалювання димовими газами

Changing the parameters of the technological mode of the process of baking carbon products allows to achieve a qualitative thermal mode, which fully determines the quality of products. Investigation of the temperature field of the furnace which depend on the technological parameters, and their rational use allows to achieve a lower output of defective products. Therefore, it is important to model these processes taking into account the maximum number of factors that will minimize the time and cost of finished products. The investigation of the influence of underpressure on the temperature fields of the furnace chamber and the process of heating the flue gases in general have been carried out. The regularities of the change in the mean value of the temperature drop across the blanks under different operating conditions were revealed. The main attention of the research was paid to the issues of homogeneity of the temperature field of blanks, which significantly affects their quality.

INFLUENCE OF THE TWO-STAGE SINTERING MODE ON STRUCTURE FORMATION AND PROPERTIES OF POWDERED ALL-PRESSED BIMETALLIC IRON-BASED MATERIALS

The paper justifies the urgency and efficiency of obtaining bimetallic iron-based materials by two-step isothermal sintering to enable forming the structure of the product bases at the first stage and activating diffusion processes in the wear-resistant layer only at the second stage to eliminate any high-porosity areas and brittle inclusions at interlayer boundaries typical for powder materials doped with carbides, nitrides and borides. The analysis of equation solutions for diffusion in two-component heterogeneous powder systems made it possible to propose an option for determining the time and temperature of homogenizing sintering of bimetallic materials taking into account grain-size distribution of powders, concentration and partial diffusion coefficients of components, charge bulk density, initial and final porosity of the products. Experiments proved that bimetallic materials containing 15– 20 wt.% of chromium carbide, 20–25 wt.% of ferrochromium and iron as the rest component in the wear-resistant layer charge have the best combination of hardness, wear resistance and radial compression strength after sintering in a chamber furnace in protective medium at 1150–1180 °C with a holding time of 1,5–2,0 hours at the first stage, and in an induction furnace at 1350– 1370 °C for 25–35 s with a heating rate of 450–470 °C/s at the second stage. Structure formation peculiarities of the interlayer boundaries and wear-resistant layer during two-step sintering of all-pressed bimetallic materials are shown. It is found that for high-temperature sintering by high-frequency (8 or 16 kHz) heating at the second stage, the depth of chromium diffusion from the wear-resistant layer to the matrix is 120–130 μm, and Cr concentration in various points of interlayer and interparticle boundaries varies between 1 and 30 wt.% thus allowing formation of a transition layer with a structure consisting of a ferritic-austenitic matrix with martensitic colonies and dispersed particles of (Cr,Fe)23C6, (Cr,Fe)7C3 and (Cr,Fe)3C2 ferrochromium carbides uniformly distributed over the volume.

Determination of optimum parameters of melting and converting of iron-containing melt with the production of vanadium-containing slag

The development of a comprehensive technology for processing titanomagnetite concentrate at the Masalsky field will enable the production of an iron-containing alloy and a vanadium product.The processing of the titanomagnetite concentrate of the Masalsky deposit includes rework firing, magnetic separation of the cinder, the melting of a large phase of the reduced metal and the magnetic fraction of the cinder, and further conversion of the cast iron to produce vanadium-containing slag and iron-containing alloy. In this paper, the main direction was to determine the optimal melting parameters and convert the iron-containing melt to produce a vanadium-containing slag. Melting of the magnetic fraction and class +0.1 mm of cinder after reduction firing was carried out at temperatures of 1400, 1450 and 1500 °C. It was found that the optimum melting temperature of the class +0.1 mm and the magnetic fraction of the cinder is 1450 ° C for 20 min. Chemical, mineralogical and electron probe analysis of the obtained alloys showed that after melting the phases become more homogeneous, structured and magnetic. The composition of the glandular matrix consists of 88-90 % of reduced iron and manganese inclusions of about 7%. The aggregative structure of the matrix is due to the presence of rounded, oval separations with a cementing mass, detected at relatively high magnifications. Vanadium in all samples is concentrated in the interstices between the rounded ferruginous segregations. Carbon together with iron is in large inclusions. Composition of the obtained cast iron, wt. %: 88.3-90.2 Feсоmm; 0.286-0.354 V; 0.012-0.236 Ti; 3.54-4.06 C. The cast iron was converted into a laboratory unit consisting of a Kejia chamber furnace, an air flow meter, an air supply pump 2FY-1B. The parameters of the conversion of cast iron were determined: a temperature interval of 1200-1450 °C, a duration of 110 minutes with an air supply of 5-10 liters / min. Vanadium-containing slags of the following composition, wt. %: 13.8-16.05 V2O5; 35.9-42.8 Fecomm; 3.5-11.17 TiO2; 3.78-17.66 SiO2; 1.6-2.9 Cr; 5.95-9.5 Mn. The composition of iron-containing alloys, wt. %: 96.8-97.1 Fecomm; 0.11-0.26 Ti; 0.1-0.14 V; 0.78-1.2 C; 0.1-0.13 Si; 0.035-0.40 Cr; 0.3-0.4 Mn. The cast iron and vanadium slag obtained by us correspond to the existing analogues in terms of the content of impuritycomponents.