Primary Furnace Research Articles

Maximal utilization of purge gas in methanol plants with improved primary furnace burners: A CFD study

The focus of this study is to achieve a better design of burners installed in petrochemical steam methane reformeing (SMR) furnaces. The initial design for the burners of the primary furnace in the Marjan petrochemical plant was problematic; hot spots occured on the side walls of the radiant chamber when the purge gas of the plant was added to the fuel stream. Three distinctive improvements have been recommended to alleviate this problem and provide higher combustion efficiency. These three suggestions include introducing pre-mixing of air and fuel streams, lowering the fuel nozzle velocity, and additional staggered nozzle holes to the base design to achieve more uniform flames. The non-premixed combustion computational fluid dynamics (CFD) simulations are conducted with ANSYS Fluent software on only one array of the burners, given the periodic boundary conditions at the two sides of each array. The resulting temperature and velocity distributions are obtained to compare the designs. The results indicate that a more uniform temperature distribution will be achievable by adding the staggered nozzle holes, which provide a heat flux of 7604 W/m2 and reduce the radiant wall’s average temperature by 0.598%. However, the combustion phenomenon occurs at its highest efficiency—99.998%—through the second design, where the fuel velocity is lowered at the nozzles. Although the first design with the pre-mixing of air and fuel performs more effectively in pushing flame towards the reformer tubes and reducing temperature variations along the radiant walls, the possibility of flash-back occurrence is high; so further safety actions must be taken into account. Eventually, the third design is chosen for implementation as economic analysis indicates that $10 million/year will be saved by lowering the amount of natural gas injected into the burners.

Research of iron extraction from primary steelmaking slag

The article examines the issue of involving primary steel making slag in the processing with the extraction of iron and the production of slag, which can be used in the manufacture of construction products. Currently, primary steel slag is not used for the production of construction products due to the large amount of iron, and its use is limited to road construction and in most cases, primary slag is sent to landfills. In the Pavlodar region of the Republic of Kazakhstan, during steel production at electric steel making enterprises, the resulting electric furnace slag and dust are stored in slag dumps. They are practically not used, despite their high content of iron oxides and metallic iron particles (up to 40% by weight in some types of slag). The work experimentally determined the chemical and mineralogical composition of primary electric furnace slag with a total iron content of more than 20%. The slag contains the following minerals: wüstite (FeO), magnetite (Fe3O4), gehlenite (Ca2Al(Al,Si)2O7), merwinite (Ca3Mg(SiO4)2). In the course of experimental studies on the recycling of primary electric furnace smelting slags by reduction induction melting of slag-lime-coke pellets, the possibility of extracting iron in the form of iron-carbon alloys and using the slags for the production of concrete was established.

Production technology for Roman mosaic glass vessels: new data from the domus of Tito Macro in Aquileia (Italy)

• Focus on Roman mosaic glass vessels, dated to the 1st cent. AD, from Aquileia (Italy). • Base glass, colourants and opacifiers consistent with Roman glass-making tradition. • No links between mosaic glass vessels and specific primary furnaces. • Mosaic vessels-makers acquired coloured rods and canes from different suppliers. • Production model of mosaic glass vessels seems to be composed of at least three steps. The present work focuses on five mosaic glass vessels from the domus of Tito Macro in Aquileia (northeastern Italy). The vessels were typogically attributed to three kinds of mosaic glass (marbled, striped mosaic, and composite mosaic patterns), all dated to the 1st century AD and obtained by the juxtaposition of translucent/transparent and opaque coloured glass pieces for a total of 25 analytical samples., They were texturally and chemically analysed by optical microscopy (OM), scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS), and electron microprobe (EPMA). The results show that base glass, colourants and opacifiers are consistent with the early Roman glass-making tradition. Textural and chemical data suggest that the vessel makers acquired coloured rods and canes from different suppliers. There were no links between vessels and specific primary furnaces or amongst various colours of different vessels and similar colours in the same object, suggesting a complex production organisation, especially for composite canes, where the production of the single colour rods was probably separated from that of the canes. The effects of working processes on glass composition are also investigated.

Estimation of phosphorus distribution ratio at the end of blowing in BOF

In integrated steel plants, the removal of phosphorous normally takes place during the primary basic oxygen furnace (BOF) steelmaking process. Phosphorous is usually introduced to the integrated steelmaking process through blast furnace additions, such as iron ore, coke, sinter, and fluxes. Among the others parameters such as optimizing the charging system, oxygen supply system, oxygen lance parameters of the converter, the flux quality in combination with temperature process control can improve the BOF efficiency of Dephosphorization. Phosphorus partition ratio (LP) is usually used to evaluate the thermodynamic efficiency of the dephosphorization of slags with different compositions in steelmaking processes. However, this parameter is only useful in equilibrium conditions, and it is not accurate when used to evaluate slag efficiency in industrial processes. Because of this, the aim of this work was to study the phosphorus partition ratio estimated from the experimental results in real plant conditions of two different BOF steel plants and compare them with well-known published models. In the present study, data from two steel plants (further Plant A and Plant B) were evaluated applying Healy’s, Suito and Inoui’s, Zhang’s as well as Assis’s equations. The calculated values were compared against measured values.

Roles of MgO and Al2O3 on the Viscous and Structural Behavior of Blast Furnace Primary Slag, Part 1: C/S = 1.3 Containing TiO2

This research provides fundamental insight into the roles of MgO and Al2O3 on the viscous and structural behaviors of CaO−SiO2−MgO−Al2O3−10 mass% TiO2−5 mass% FeO (CaO/SiO2 = 1.3) system primary blast furnace slag. The slag viscosity is measured by the rotating cylinder method, which is essential to the efficient and stable operation of a blast furnace. The network structure characterization of the quenched vitreous samples was conducted using Fourier Transformation Infrared (FTIR) and Raman spectroscopy. Usual viscous behaviors (that the slag viscosity and the activation energy decrease or increase with increasing MgO or Al2O3 content) were observed, corresponding to changes in the network structure certified by FTIR and Raman analyses. It seems that the addition of MgO and Al2O3 prefers to modify the Si−O and Ti−O network in the present slag. When the slag composition reaches 10% MgO and 12% Al2O3, unexpected viscous behaviors (that MgO increases viscosity and Al2O3 decreases viscosity) are discovered. The roles of MgO and Al2O3 could be interpreted by changes in the arrangement structure of ions in liquid, corresponding to changes in the primary equilibrium phase region determined in phase diagrams and variation in the difference between the experimental and liquidus temperature, respectively.

Kinetic model of ignition and combustion of finely-disperse coal-water fuel

The article proposes a model of the process of ignition and combustion of fine water-coal fuel (FWCF) in a cyclone primary furnace. The model is intended to form an engineering approach to calculating the composition and quantity of combustion products of the FWCF and the definition of the structural and layout characteristics of the actual cyclone primary furnace. Approximation of process modeling is determined by the following assumptions: the quasistationarity of the processes; the constancy of heat capacities and heat transfer coefficients at an average process temperature; isothermal fuel particles; representation of fuel particles in the form of a water-coal drop of a given size; inertness of ash components; record keeping of the determining chemical reactions of interaction with the oxidizing agent; one-dimensional flow. This approach allows to carry out an analytical analysis of the process and to obtain final expressions suitable for engineering calculations.

Characterisation of Byzantine and early Islamic primary tank furnace glass

In order to improve the understanding of glass production and provenance, we present trace element and Sr, Nd and B isotope ratio data for 15 samples of raw natron glass from a single tank furnace in Apollonia (6th–7th century CE) and eight glass samples from two tank furnaces in Bet Eli'ezer (8th century CE) in Israel. This data provides information about the geochemical homogeneity within a single batch of raw glass and about the differences and/or similarities between different tank furnaces on a single site. Four glasses from a secondary workshop at Tell el-Ashmunein, Egypt (8th–9th century CE) are analysed for comparative purposes.All raw glass samples have uniform trace element patterns and ratios. Because of poor mixing of the glass batch before and during firing, absolute concentrations however can vary significantly within a single tank furnace. The concentrations of trace elements commonly associated with (de)colouring are very low and can be attributed to background concentrations in the sand raw materials. This indicates that there was no obvious recycling of glass cullet at this stage of the production process and that the tank furnace glass is primary glass in the true sense of the word. The isotopic compositions of Sr, Nd and B in the tank furnace glasses are relatively homogeneous. This confirms their potential as provenance indicators. The isotopic composition of Sr in tank furnace glass from Apollonia and Bet Eli'ezer indicates that the lime was derived from seashell, suggesting the glass was produced from beach sand. Glass from Tell el-Ashmunein contains Sr with lower 87Sr/86Sr ratios, pointing to the use of limestone as the source of lime. All primary glasses from Israel analysed have Nd isotopic compositions typical for an Eastern Mediterranean origin. δ11B indicates that natron used in the tank furnaces in Apollonia and Bet Eli'ezer was most likely imported from Egypt.

Working glass in Ptolemaic Egypt, a new evidence from Denderah

The current knowledge of both glass-making and glass-working in Ptolemaic Egypt is very poor. Excavations and surface surveys conducted in the region of Alexandria and in the Wadi Natrun located primary glass-making furnaces, but these appear to be later productive centres, operating only since the first century CE. Presently, we do not know any earlier primary workshop and it is also difficult to understand clearly which glass objects were actually produced in Ptolemaic Egypt. The reference to Alexandria in the ancient sources, as a glass producer, has shaped a centralized model, widely accepted in literature, with the capital acting as the leading centre for both glass-making and glass-working.However, the only glass-working sites located in Ptolemaic Egypt are four workshops specialised in making both monochrome and millefiori inlays, i.e. small plaques used to decorate religious and funerary furniture and none of them is in Alexandria. A survey conducted on glasses in the collections of the Egyptian Museum of Cairo allowed to identify a new large assemblage of glass finds, interpretable as glass-working waste from a further workshop making inlays, excavated in Denderah (Upper Egypt), at the beginning of the 20th century. This paper presents the preliminary results of a morphological observation conducted on unworked glass (cakes, lumps and chips from the workshop). The results suggest a technological continuity with LBA Egyptian tradition and the possibility that glass colouring was practiced in Denderah, inserting glass-working in the activities administrated by temples and located in the annexes.

МЕТОДЫ ВЫБОРА РАЦИОНАЛЬНОГО СОСТАВА ДОМЕННОЙ ШИХТЫ

The aim of the work is to solve the problem of choosing the optimal composition of iron ore materials for blast furnace loading. An analytical review of the existing approaches to assessing the quality and methods for selecting a rational composition of iron ore materials implemented as part of the control system of domestic and foreign blast furnaces in modern conditions has been carried out. A method of modeling the processes of directional formation of melts, developed at the Iron and Steel Institute, is proposed. The description of the processes of transformation of iron ore materials in a blast furnace and the properties of liquid smelting products was carried out using the parameters of interatomic interaction in melts. The technique uses a set of integral criteria and physicochemical models that allow estimating charge, gas-dynamic and temperature melting conditions. The influence of the quality of iron ore on the properties of primary melts and final products of blast-smelting is analyzed. An integral indicator of the quality of the charge and an integral indicator of the temperature blast mode have been developed. The main difference of the proposed approach to the selection of the composition of the charge from similar developments focused on the traditional criterion «basicity of the final slag» is the use of a set of physico-chemical criteria that characterize the quality and properties of iron ore, primary and final blast furnace slag. The use of the developed prognostic models and criteria as part of automated blast furnace control systems allows us to predict the chemical composition of iron and slag. Stabilization of slag properties within the specified limits ensures the smelting of cast iron of the required composition and a reduction in coke consumption in the current unstable conditions of smelting iron.

Failure Analysis of a Service Tube

One tube was cracked used in the primary reformer furnace in a fertilizer plant for two and half years. In order to find out the causes of cracking, the methods for chemical composition analysis, macro- and microstructure analysis, penetrant testing, weld analysis, crack and surface damage analysis, mechanics property analysis, high temperature endurance performance analysis, stress and wall thickness calculation were adopted. The integrated assessment results showed that the carbon content of the tube was in the lower limit of the standard range; the tube effective wall thickness was too small; local overheating leads to tube cracking in use process.

Estimation and Analysis of Excess Oxygen Input into Ladle During Liquid Steel Tapping

Carryover of oxidising slag from primary steelmaking furnace during tapping affects the quality of liquid steel in several ways. Secondary steelmaking practices, such as deoxidation, desulphurization, vacuum degassing as well as inclusion control in liquid steel bath, are greatly influenced by the amount and characteristic of carryover slag. Both, slag volume as well as ferro alloy consumption increases due to the presence of carryover slag during ladle refining treatment. Carryover of furnace slag in ladle during tapping cannot be avoided and results in consumption of excess electrical energy. Thus, control of carry over slag mainly during tapping is essential by suitably modifying the operational practice. In the present investigation, slag carry over during liquid steel tapping operation is quantified for the processed data obtained from an integrated steel plant based on material balance and equilibrium thermodynamic study. Some of the relevant operational factors related to slag, deoxidation, temperature and solutes (C, S and N) are identified and correlated with the amount of slag carry over. Though, the slag carry over during tapping operation is gravity dependent draining phenomena, scope for controlling the same is identified & discussed in the present study.

Evaluation of particulate matter emissions from manganese alloy production using life-cycle assessment

Life-cycle assessments (LCAs) provide a wealth of industry data to assist in evaluating the environmental impacts of industrial processes and product supply chains. In this investigation, data from a recent LCA covering global manganese alloy production was used to evaluate sources of particulate matter (PM) emissions associated with the manganese alloy supply chain. The analysis is aimed at providing an empirical, industry-averaged breakdown of the contribution that processes and emissions controls have on total emissions, manganese releases and occupational exposure.The assessment shows that 66% of PM emissions associated with manganese production occur beyond manganese facilities. Direct or on-site emissions represent 34% of total PM and occur predominantly as disperse sources during mineral extraction and hauling, and as primary furnace emissions. The largest contribution of manganese-bearing PM at ground-level is associated with fugitive emissions from metal and slag tapping, casting, crushing and screening.The evaluation provides a high-level ranking of emissions by process area, to assist in identifying priority areas for industry-wide initiatives to reduce emissions and occupational exposure of manganese. The range of PM emission levels in industry indicate that further enhancements in PM emissions can be achieved by sharing of best practices in emissions controls, limiting furnace conditions which lead to by-passing of emissions controls and application of secondary emission controls to capture fugitive emissions during tapping and casting. The LCA approach to evaluating PM emissions underscores the important role that process optimization and resource efficiency have on reducing PM emissions throughout the manganese supply chain.

Microstructural and failure analysis of welded primary reformer furnace tube made of HP-Nb micro alloyed heat resistant steel

Abstract In this paper, the failure of the reformer furnace tube, made of HP-Nb micro alloyed heat resistant steel is investigated. The failure was due to a longitudinal crack developing in the circumferential weld joint close to the outlet end of the tube, where the mean wall temperature had reached the highest value during service. According to the temperature records during the period of 7 years of being in service, the tube had experienced temperatures higher than the tubes designed temperature. This situation besides the occurrence of several sudden shutdowns caused the mechanical properties degradation. Macroscopic and microscopic examinations revealed that the failure had occurred due to the extensive fissuring initiated and developed from the heat affected zone (HAZ) adjacent to the root weld. The results of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) analysis, and the crack growth rate calculations indicated that the crack propagation rate was controlled by the overheating and the secondary thermal stress due to the sudden shutdowns. Moreover, the ductility at the tip of the crack had dwindled due to the nitrogen uptake at high temperature, which promoted the crack growth rate. Quantitative microstructural analysis performed at the uncracked and cracked sides of the weld joint showed that the area fraction of HAZ creep cavities were 0.3% and 0.7%, respectively, which were interpreted in turn as the accumulated creep damage level D and E. Finally, it was concluded that the creep cavities alignment and fissuring that took place at HAZ are the main causes of the cracking and failure of the tube.

Conversion of KVGM-100–150 boilers to cyclone-swirl burning of gas

Heating sources of Vladivostok with boilers reconstructed in 2011 to gas burning is presented. The historical reference of the experience of boiler conversion to cyclone-swirl technology of burning of fuel oil and gas is given. Stages of the primary furnace and boiler upgrading are shown. Taking BKZ 75-16 and BKZ-120-100 boilers as examples, the principal differences of the swirl type of fuel burning from the burner type are demonstrated. Data of the KVGM-100–150 MTs boiler with cyclone-swirl burning of gas and fuel oil is represented. The mathematical model developed for the primary furnace with the 65 MW capacity gives detailed explanations to the features of mixing in the combustion chamber of the primary furnace, which substantiate conditions and places of the fuel injection. The practical result is supported by test data obtained on the operating equipment. To enhance the effectiveness of fuel consumption on six converted KVGM-100-150 MTs boilers, the convective section was restructured and the water circulation circuit was optimized. Comparative analysis of estimated and operating characteristics showed the efficiency increment. The application of cyclone-swirl technology made it possible to increase the effectiveness of the KVGM-100-150 boiler and improve its environmental indicators.

The promise [and uncertainties] of Biochar

The promise [and uncertainties] of Biochar

Analysis of modern methods of combustionof lignite in primary furnace

The article analyzes the methods of heat treatment of lignite in primary furnace in order to create an efficient primary furnace for burning solid fuel with small dimensions. The article provides an overview of the existing technologies of combustion of solid fuel in the primary furnaces of steam boilers, and tested heat treatment technologies of lignite in a fluidized bed and in the vortex, in a fixed or movable dense layer, and in a circulating fluidized bed. From the above-mentioned methods of combustion of solid fuel for the heat treatment of lignite, the best is the cyclone or vortex method. It differs from others by the least necessary dimensions of the principal and auxiliary equipment. If the furnace provides a complete combustion mode, the ash will not contain carbon, and contraction at the outlet of the cyclone will prevent much of the ash in the boiler of the furnace. If the effective heat treatment of gas coal, without initiating fuel usually requires the temperature level of molten slag, for the more reactive lignite it may be sufficient to maintain the temperature not much less than the softening point of the ash. This greatly simplifies the deashing and requirements to materials of internal lining. This analysis can be used when developing new technologies of combustion of lignite in primary furnace installed in front of the existing boiler units designed to combust both coal and natural gas or fuel oil, mainly used in the municipal power system of Ukraine.

Western Mediterranean sand deposits as a raw material for Roman glass production

During the Late Roman and Byzantine period, natron glass was made from its raw materials in a limited number of primary production centres in Egypt and Syro-Palestine. For the earlier Hellenistic and Roman period, no primary furnaces have been found and the location of primary production during this era remains unclear. Ancient authors such as Strabo and Pliny the Elder suggest that glassmaking sands were found near the River Belus (Israel), in Egypt, near the mouth of the Volturno River (Italy) and also in Spain and France. However, primary production in the western part of the Mediterranean is not supported by any direct archaeological evidence and possible sand raw materials from these regions have never been evaluated for their suitability to produce glass.In this study 178 modern beach sands from Spain, France and Italy were analysed for their major and minor elemental compositions. By calculating the composition of the glasses that can be produced with these sediments after the addition of pure natron, and comparison with the composition of typical Roman natron glass, we were able to judge whether or not these sands are suitable for Roman glass production. The results indicate that good glassmaking sands are rather rare. Only a very limited number of the 178 analysed beach sands would produce a glass with major and minor elemental compositions within the ranges of Roman imperial natron glass. The rest of the analysed sands are unsuitable for glass production in their present form due to their insufficient SiO2, high Al2O3 and Fe2O3 and either too low or too high CaO contents. If the sand raw material was too low in CaO, extra lime could be added to the glass batch in the form of shell or limestone. This was taken into account in a second calculation.Overall we were able to define six limited areas where suitable sand raw materials would have been available to the Roman glassmaker. Good glassmaking sands occur in the Basilicata and Puglia regions (SE Italy), and Tuscany (W Italy). After the addition of an extra source of lime also sands from the Huelva province (SW Spain), the Murcia region (SE Spain) and from the Provence (SE France) would produce glasses with a typical Roman composition.

Combustion of coal, bagasse and blends thereof: Part I: Emissions from batch combustion of fixed beds of fuels

Batch combustion of fixed beds of coal, bagasse and blends thereof took place in a pre-heated two-stage electric laboratory furnace, under high-heating rates. The average input fuel/air equivalence ratios were similar for all fuels. The primary and secondary furnace temperatures were varied from 800°C to 1000°C. The effects of fuel blending, combustion staging, and operating furnace temperatures on the emissions from the two fuels were assessed. Furnace effluents were analyzed for carbon dioxide and for products of incomplete combustion (PIC) including CO, volatile and semi-volatile hydrocarbons, as well as particulate matter. Results showed that whereas CO2 was generated during both the observed sequential volatile matter and char combustion phases of the fuels, PICs were only generated during the volatile matter combustion phase. CO2 emissions were the highest from coal, whereas CO and other PIC emissions were the highest from bagasse. Under this particular combustion configuration, combustion of the volatile matter of the blends resulted in lower yields of PIC, than combustion of the volatiles of the neat fuels. Though CO and unburned hydrocarbons from coal as well as from the blends did not exhibit a clear trend with furnace temperature, such emissions from bagasse clearly increased with temperature. The presence of the secondary furnace (afterburner) typically reduced PIC, by promoting further oxidation of the primary furnace effluents.

Identification of complex nonlinear processes

The estimation of the unknown parameters in models described by algebraic equations, ordinary differential equations, and partial differential equations, as well as the initial state vectors in these models, was carried out by the maximum plausibility technique. As in problems of parametrical identification, quality functions have a complex form and contain a significant number of local minimums; to decrease their amount and simplify the form of the quality function in regions far from the absolute minimum, the method of asymptotic decomposition was suggested for problems of the identification and estimation of the parameters. For the application of the suggested procedure, the technology of the parametrical identification of the physical-chemical processes in a furnace plant working in the mode of gas production with a fluid bed was introduced. A measurement model was developed by the experimental data obtained during the combustion of brown coals in primary furnaces with a fluid bed at HES-2 in Chelyabinsk.

Thermal treatment of polychlorinated dibenzo- p-dioxins and dibenzofurans from contaminated soils

Thermal treatment technology was used to remove polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) from heavily contaminated soil. For a soil with an original PCDD/F content of 35,970 ng International Toxic Equivalents (I-TEQ)/kg, >99.99% PCDD/F removal efficiency was obtained with a primary furnace at two different treatment temperatures (750 °C and 850 °C), while a secondary furnace at 1200 °C gave >98% decomposition efficiency. The total PCDD/F I-TEQ contents in treated soils at 750 °C and 850 °C were 1.56 ng I-TEQ/kg and 2.15 ng I-TEQ/kg, respectively, which were far below the soil pollution standard of Taiwan (1000 ng I-TEQ/kg soil). Although air pollution control devices had significant effects on the removal of PCDD/Fs, the total I-TEQ concentrations in the upstream flue gas of PUF cartridge at 750 °C and 850 °C (2.61 ng I-TEQ/Nm 3 and 2.38 ng I-TEQ/Nm 3, respectively) were still higher than the stationary emission limit of the Taiwan EPA (0.5 ng I-TEQ/Nm 3). The above results also suggested that additional APCDs, such as activated carbon injection in front of the filter are needed to enhance PCDD/F removal efficiency.