Kiln

Distribution by Scientific Domains

Kinds of Kiln

  • cement kiln
  • rotary cement kiln


  • Selected Abstracts


    LEAD ISOTOPE ANALYSIS OF TANG SANCAI POTTERY GLAZES FROM GONGYI KILN, HENAN PROVINCE AND HUANGBAO KILN, SHAANXI PROVINCE

    ARCHAEOMETRY, Issue 4 2010
    J. F. CUI
    Through the use of MC,ICP,MS, this study analyses the lead isotope ratios of 19 Tang Sancai pottery glazes unearthed from the Gongyi and Huangbao kiln sites. According to their different lead isotope ratios, the two kilns can be grouped separately. The research also suggests that the Gongyi and Huangbao kilns are independent production centres of Tang Sancai in the Tang Dynasty. The data from the Huangbao kiln indicates that the lead in the glazes originates from the Northern China geochemical province, while the data from Gongyi kiln suggests its source as the Yangtze geochemical province. Furthermore, the results obtained for the Tang Sancai pottery indicate that the lead sources for glaze making of these two kilns were very consistent, which suggests that lead isotope analysis could be a helpful method to identify the kilns producing Tang Sancai artefacts. [source]


    PETROGRAPHIC AND CHEMICAL CHARACTERIZATION OF POTTERY PRODUCTION OF THE LATE MINOAN I KILN AT HAGHIA TRIADA, CRETE,

    ARCHAEOMETRY, Issue 4 2007
    C. M. BELFIORE
    Pottery from the Late Minoan I kiln at Haghia Triada in the Mesara Plain, southern Crete, was analysed by a range of techniques, comprising thin-section petrography, scanning electron microscopy, X-ray diffraction, X-ray fluorescence and neutron activation analysis. The project characterizes the ceramic fabrics and probable raw materials, correlates paste recipes with shape, reconstructs the firing conditions of the kiln and establishes a chemical reference group, taking into account post-burial alteration and contamination. Comparison of the reference group formed with that from the neighbouring, broadly contemporary, kiln at Kommos shows an unexpected differentiation of the two kilns. [source]


    THE BLUE ENAMELS IN THE BAROQUE DECORATIONS OF THE CHURCHES OF PALERMO, SICILY: FE2+ -COLOURED GLASSES FROM LIME KILNS*

    ARCHAEOMETRY, Issue 2 2009
    G. ARTIOLI
    Deep blue glasses coloured by octahedral Fe2+ cations are often reported as textbook examples of blue pigmentation. However, despite the possibility of laboratory synthesis under reducing conditions, to date there are no well-reported occurrences of their production and use in the past. A thorough historical, ethnographic, mineralogical, and chemico-physical investigation of the ,smaltini di calcara' from several baroque churches in Palermo, Sicily, has revealed that the blue enamels widely used for altar decorations in the 17th and 18th centuries are actually a unique case of ancient blue glasses pigmented by divalent iron cations in distorted octahedral coordination. This mixed-alkali glass was accidentally produced under severely reducing conditions in the local kilns during production of lime. [source]


    Chemical Composition of Ancient Celadon Material (1127,1279 A.D.) from Zhejiang, China and Its Implication

    ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2006
    PENG Zicheng
    Abstract: The microprobe EDXRF equipment was used for analysis of the major and trace elements in glaze layer-transitive layer-body layer of the celadon from the Altar Yao (Kiln) and Laohudong Yao in the Southern Song Dynasty (1127,1279 A.D.), Zhejiang, China. The K values of the discriminant factor for the celadon wares are larger than 8, which means the celadon of the Altar Yao and Laohudong Yao are different from that of the Longquan Yao. The former two belong to the Guan Yao system (the Chinese imperial kilns), but the latter to the Min Yao system (the Chinese popular kilns). The principle component analysis shows their relationship between the Altar and Laohudong wares with provenance postulation. The thickness of the transitive layer in the Altar and Laohudong wares is obviously different, which reveals the microstructure characteristics of the celadon even though both kinds of wares belong to the imperial kiln system. [source]


    Progress in the Modelling of Air Flow Patterns in Softwood Timber Kilns

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2004
    T.A.G. Langrish
    Progress in modelling air flow patterns in timber kilns using computational fluid dynamics (CFD) is reviewed in this work. These simulations are intended to predict the distribution of the flow in the fillet spaces between boards in a hydraulic model of a timber kiln. Here, the flow regime between the boards is transitional between laminar and turbulent flow, with Reynolds numbers of the order of 5000. Running the simulation as a transient calculation has shown few problems with convergence issues, reaching a mass residual of 0.2% of the total inflow after 40 to 100 iterations per time step for time steps of 0.01 s. Grid sensitivity studies have shown that non-uniform grids are necessary because of the sudden changes in flow cross section, and the flow simulations are insensitive to grid refinement for non-uniform grids with more than 300,000 cells. The best agreement between the experimentally-measured flow distributions between fillet spaces and those predicted by the simulation have been achieved for (effective) bulk viscosities between the laminar viscosity for water and ten times that value. This change in viscosity is not very large (less than an order of magnitude), given that effective turbulent viscosities are typically several orders of magnitude greater than laminar ones. This result is consistent with the transitional flows here. The effect of weights above the stack can reduce the degree of non-uniformity in air velocities through the stack, especially when thick weights are used, because the stack may then be separated from the eddy at the top of the plenum chamber. [source]


    Combustion of a substitution fuel made of cardboard and polyethylene: influence of the mix characteristics,modeling

    FIRE AND MATERIALS, Issue 7 2008
    S. Salvador
    Abstract The model proposed in this paper describes the combustion of a porous medium subjected to a radiative heat flux at its surface. There is no forced convection of air through the medium; hence this situation corresponds to the one encountered at the surface of fuel elements such as pellets, bricks or ballots, inside a furnace or kiln. Ash is not removed from the surface. No assumption is made a priori in terms of the limiting phenomena. The medium is composed of cardboard and polyethylene (PE). Based on previous experimental work (Fuel 2004; 83:451,462), the material is assumed to be a macroscopically homogeneous porous medium. Local thermal equilibrium is also assumed. Most of the parameters required for the modeling were determined from specific experiments. Good predictions of the sample mass evolution and of the temperature levels inside the sample body were obtained for a large range of densities and PE content. A devolatilization front of about 20,mm first propagates inside the medium. The volatile matter flux is advected to the surface, which leads to the formation of the flame above the surface. Then a second char oxidation front propagates, starting from the surface. The front thickness is approximately 25,mm under the experimental conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    Early pyrotechnology in the Near East: Experimental lime-plaster production at the Pre-Pottery Neolithic B site of Kfar HaHoresh, Israel

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2008
    Y. Goren
    A characteristic hallmark of the Pre-Pottery Neolithic B (PPNB) in the southern Levant was the extensive use of lime plaster for architectural and other purposes. Yet no obvious kilns have been identified in archaeological contexts. Here we present details of an experimental pit-kiln modeling lime-plaster production based on observed burnt stone accumulations in pits at the PPNB site of Kfar HaHoresh in the lower Galilee. The experimental kiln was loaded in layers with ,500 kg of limestone (pebbles and stones) and ,1000 kg of fuel (branches and dung). Fired for 24 hours, and reaching a maximum 870°C, the kiln yielded almost 250 kg of quicklime (calcium oxide, CaO). Micromorphological samples, general observations, and scaled plan view drawings made immediately following and nine years after ignition demonstrate that the original shape of the kiln and residual quicklime within and around it rapidly dissipated through bioturbation, trampling by animals, erosion, rain, and exposure to the elements. This could account for the seeming absence of kilns within sites, although they were probably located close to where lime-plaster was applied, given the unstable nature and toxic effects of handling quicklime. Calculations of the manpower and fuel involved indicate that PPNB lime-plaster production may have been less labor intensive and less detrimental to the environment than previously portrayed. © 2008 Wiley Periodicals, Inc. [source]


    Estimating baking temperatures in a Roman pottery kiln by rock magnetic properties: implications of thermochemical alteration on archaeointensity determinations

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2006
    Simo Spassov
    SUMMARY Absolute past geomagnetic field intensity determinations requiring laboratory heating are labourious and the success rate is rather low, mostly because of induced thermochemical magnetic mineral alterations. Archaeomagnetic intensity determinations are mainly limited to displaced ceramics produced in kilns. In this study, the suitability of an in situ baked structure is investigated. Different magnetic properties of baked material taken from the combustion chamber wall and floor of a Roman pottery kiln, with variable colouring, are examined in dependence on the distance to the combustion chamber. The temperature distribution is re-constructed based on rock magnetic experiments after stepwise heating. The rock magnetic temperature estimates agree fairly well with a mathematical heat conduction model demonstrating the penetration of heat into the combustion chamber wall. The rock magnetic results show that blackish- and greyish-coloured kiln parts, that had been in close contact with the fuel, during ancient kiln operation, are not suitable for intensity determinations. Although sufficiently baked, they strongly alter during laboratory heating and new remanence-carrying minerals are formed. The brownish-coloured material at a distance 65,80 mm away from the combustion chamber seems to be most suitable as its magnetic properties remain nearly unchanged during laboratory heating. Rock magnetic and modelled temperature estimates for this material consistently indicate ancient baking temperatures of about 600°C. The model demonstrates that cooling takes longer in the inner parts of the combustion chamber wall. Retarded cooling affects the blocking temperatures and hence the strength of the thermoremanent magnetization. The variability of cooling rates should be taken into account when investigating archaeointensities of specimens cut from large samples, or of samples taken from different parts of a kiln. [source]


    Experimental modelling and intelligent control of a wood-drying kiln

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2001
    Givon Chuen Kee Yan
    Abstract Proper control of the wood-drying kiln is crucial in ensuring satisfactory quality of dried wood and in minimizing drying time. This paper presents the development, implementation, and evaluation of a control system for a lumber drying kiln process incorporating sensory feedback from in-wood moisture content sensors and intelligent control such that the moisture content of lumber will reach and stabilize at the desired set point without operator interference. The drying process is difficult to model and control due to complex dynamic nonlinearities, coupling effects among key variables, and process disturbances caused by the variation of lumber sizes, species, and environmental factors. Through system identification scheme using experimental data and recursive least-squares algorithm for parameter estimation, appropriate models are developed for simulation purpose and controller design. Two different control methodologies are employed and compared: a conventional proportional-integral-derivative (PID) controller and a direct fuzzy logic controller (FLC), and system performance is evaluated through simulations. The developed control system is then implemented in a downscaled industrial kiln located at the Innovation Centre of National Research Council (NRC) of Canada. This experimental set-up is equipped with a variety of sensors, including thermocouples for temperature feedback, an air velocity transmitter for measuring airflow speed in the plenum, relative humidity sensors for measuring the relative humidity inside the kiln, and in-wood moisture content sensors for measuring the moisture content of the wood pieces. For comparison, extensive experimental studies are carried out on-line using the two controllers, and the results are evaluated to tune the controller parameters to achieve good performance in the wood-drying kiln. The combination of conventional control with the intelligent control promises improved performance. The control system developed in this study may be applied in industrial wood-drying kilns, with a clear potential for improved quality and increased speed of drying. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    Process Optimization in Tableware Industries Using Taguchi's Design of Experiments

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2010
    Birgit Palm
    The essential influences of 15 parameters on defects (cracks and bubbles) during production of tableware have been studied with 16 experimental progressions using a L16(215) experimental design by G. Taguchi. Evaluation (analysis of means and analysis of variance) indicated that in this production liter weight, drying time, moisture before biscuit firing, and position in the biscuit-firing kiln have a significant influence on cracks. Concerning bubbles, parameters with an influence are liter weight, gate system, mold material, and moisture content before glost firing. Rejects of the article used in the experiments were reduced from 2.44% to 2.27% with respect to cracks and from 6.22% to 0% with respect to bubbles. [source]


    Comparison of drying behaviour, quality and yield of copra processed in either a solar hybrid dryer on in an improved copra kiln

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2007
    Thiruchelvam Thanaraj
    Summary Drying copra in a solar hybrid dryer reduces the moisture content from around 50% to 7% after 71 h of continuous drying. The copra was graded as 73% white copra, 21% Milling Ordinary Grade II (M.O.GII) and the remaining 6% M.O.GIII (dusty copra). Thermal efficiency was about 10%. In the Coconut Research Institute copra kiln, the moisture content of copra was reduced from around 52% to 8% in 62 h of intermittent dying. The copra was graded as about 82% M.O.GI and the remaining 18% M.O.GIII (burnt copra). Thermal efficiency was about 15.5%. High quality white copra could be processed in solar hybrid drying. However, no white copra could be processed in kiln drying. [source]


    Olive oil mill waste water as a replacement for fresh water in the manufacture of fired clay bricks

    JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2006
    Houda Mekki
    Abstract This paper describes the introduction of olive mill wastewater (OMW) to replace fresh water normally used in clay brick manufacture. OMW is recognised as the major agro-food industry pollutant in the Mediterranean/North African olive-growing region. The research involved adding OMW to laboratory-produced clay bricks following the same making procedure used at a collaborating Tunisian brick factory. The samples containing OMW were found to be comparable in forming/extrusion performance to a control product that used fresh water. If introduced at the factory scale, this innovation would allow a substantial volume of OMW to be recycled, saving on the fresh water currently used in the brick-forming process. During the subsequent brick drying operation, most of the OMW (,98% water) would be released as vapour. Once in the kiln, the remaining solids in the bricks (calorific value 21,23 MJ kg,1) would liberate additional heat, reducing the gross energy from fossil fuel currently required during firing. Copyright © 2006 Society of Chemical Industry [source]


    Cement Manufacture and the Environment: Part I: Chemistry and Technology

    JOURNAL OF INDUSTRIAL ECOLOGY, Issue 1 2002
    Hendrik G. van Oss
    Summary Hydraulic (chiefly portland) cement is the binding agent in concrete and mortar and thus a key component of a country's construction sector. Concrete is arguably the most abundant of all manufactured solid materials. Portland cement is made primarily from finely ground clinker, which itself is composed dominantly of hydraulically active calcium silicate minerals formed through high-temperature burning of limestone and other materials in a kiln. This process requires approximately 1.7 tons of raw materials per ton of clinker produced and yields about 1 ton of carbon dioxide (CO2) emissions, of which cal-cination of limestone and the combustion of fuels each con-tribute about half. The overall level of CO2 output makes the cement industry one of the top two manufacturing industry sources of greenhouse gases; however, in many countries, the cement industry's contribution is a small fraction of that from fossil fuel combustion by power plants and motor vehicles. The nature of clinker and the enormous heat requirements of its manufacture allow the cement industry to consume a wide variety of waste raw materials and fuels, thus providing the opportunity to apply key concepts of industrial ecology, most notably the closing of loops through the use of by-products of other industries (industrial symbiosis). In this article, the chemistry and technology of cement manufacture are summarized. In a forthcoming companion ar-ticle (part II), some of the environmental challenges and op-portunities facing the cement industry are described. Because of the size and scope of the U.S. cement industry, the analysis relies primarily on data and practices from the United States. [source]


    Solid-solid reactions in series: A modeling and experimental study

    AICHE JOURNAL, Issue 9 2009
    A. K. Suresh
    Abstract Reactions among particulate solid phases are important and abundant in many materials, chemical, and metallurgical process industries. Many of these are reaction networks, and not single-step reactions as normally assumed. There is no theoretical framework available for the analysis of such systems, and single-reaction models derived from the gas,solid literature continue to be used. Formation of cement clinker in the rotary cement kiln is a prime example of the genre, in which mechanistic aspects play an important role in determining energy efficiency and the composition and nature of the phases that form. In the present study, we formulate a model within the ambit of the "shrinking core" class of models, for reactions in series among solid phases. The model shows the presence of one or two moving fronts in the reacting particle, depending on the relative rates of the processes involved. A single Thiele-type parameter controls the model behavior, at once describing the relative rates of the intermediate formation and consumption processes, and the diffusion-reaction competition for the product formation step. The model has been shown to reduce to the well known single reaction models at the limits of low and high values of the Thiele parameter. Experimental data have been obtained on the calcia-alumina system, an important one in cement manufacture, in the temperature range 1150,1250°C. The model has been fitted to these data and the kinetic parameters determined. The comparison bears out the salient features of the theory, and shows that a degree of diffusion limitation exists for the intermediate conversion step under these conditions. The diffusivity values estimated are in the range of 10,19 to 10,18 m2/s and agree with values found in the literature for similar systems. The rate constant for the intermediate conversion step is of the order of 10,6 s,1. This being among the first such determinations, this value awaits confirmation from other studies. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]


    HAZARDOUS WASTE DISPOSAL: A WASTE-FUEL BLENDING APPROACH

    PRODUCTION AND OPERATIONS MANAGEMENT, Issue 3 2003
    A. DALE FLOWERS
    The disposal of hazardous wastes creates major economic and environmental problems. One productive use of hazardous wastes is to blend them into fuel, which mitigates damage to the environment by recycling waste into fuel and reducing fossil-fuel consumption. Operations personnel face a daunting task of efficiently blending hazardous waste into fuel, while simultaneously maintaining environmental regulatory requirements. This research develops a goal-programming approach to the waste-fuel-blending process that considers the diverse objectives of fuel managers. A realworld case study at a cement kiln illustrates the effectiveness of this approach, where the implementation followed principles of team building and quality management. [source]


    Application of magnetic and spectrometry methods in the detection of human activity in soils: a case study at the archaeological site of Kitros (Northern Greece)

    ARCHAEOLOGICAL PROSPECTION, Issue 3 2001
    E. V. Aidona
    Abstract In the present study the archaeological site of (Louloudies,Kitros) (northern Greece) is investigated by the use of magnetic and spectrometry geophysical methods. Soil samples were collected from several trenches within the archaeological site, as well as from radial traverses around kilns, which were used for glass production. Moreover, samples were collected from a long traverse, starting from the middle of the archaeological site and extending outside the site, in order to identify the limits of the settlement. Measurements were successful in identifying the different occupation levels and the boundaries of the archaeological site. High values of magnetic susceptibility and iron oxide content correlated well with the periods of intense human activity. Around the kilns, the mean values of the magnetic susceptibility indicated the effect of the fire mechanism in the surrounding area and gave some first evidence concerning the use of the kilns. Comparison of the magnetic and chemical properties of the anthropogenic soils suggests that their enhancement may be used as an index for locating areas and features of archaeological interest. Additionally, archaeomagnetic data have been obtained from a pottery and a glass kiln of the site. The magnetic directions (D = 355°, I = 62°, a95 = 3.6 and D = 356°, I = 51°, a95 = 2.3) were correlated to the reference curves compiled for Bulgaria and showed a satisfactory consistency for the declination, but the inclination values of the recorded magnetic field were divergent by about 10°. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    LEAD ISOTOPE ANALYSIS OF TANG SANCAI POTTERY GLAZES FROM GONGYI KILN, HENAN PROVINCE AND HUANGBAO KILN, SHAANXI PROVINCE

    ARCHAEOMETRY, Issue 4 2010
    J. F. CUI
    Through the use of MC,ICP,MS, this study analyses the lead isotope ratios of 19 Tang Sancai pottery glazes unearthed from the Gongyi and Huangbao kiln sites. According to their different lead isotope ratios, the two kilns can be grouped separately. The research also suggests that the Gongyi and Huangbao kilns are independent production centres of Tang Sancai in the Tang Dynasty. The data from the Huangbao kiln indicates that the lead in the glazes originates from the Northern China geochemical province, while the data from Gongyi kiln suggests its source as the Yangtze geochemical province. Furthermore, the results obtained for the Tang Sancai pottery indicate that the lead sources for glaze making of these two kilns were very consistent, which suggests that lead isotope analysis could be a helpful method to identify the kilns producing Tang Sancai artefacts. [source]


    PETROGRAPHIC AND CHEMICAL CHARACTERIZATION OF POTTERY PRODUCTION OF THE LATE MINOAN I KILN AT HAGHIA TRIADA, CRETE,

    ARCHAEOMETRY, Issue 4 2007
    C. M. BELFIORE
    Pottery from the Late Minoan I kiln at Haghia Triada in the Mesara Plain, southern Crete, was analysed by a range of techniques, comprising thin-section petrography, scanning electron microscopy, X-ray diffraction, X-ray fluorescence and neutron activation analysis. The project characterizes the ceramic fabrics and probable raw materials, correlates paste recipes with shape, reconstructs the firing conditions of the kiln and establishes a chemical reference group, taking into account post-burial alteration and contamination. Comparison of the reference group formed with that from the neighbouring, broadly contemporary, kiln at Kommos shows an unexpected differentiation of the two kilns. [source]


    A scientific study of Choson white ware: early porcelain from a royal kiln at Kwangju Usanni

    ARCHAEOMETRY, Issue 2 2002
    C. K. Koh Choo
    Scientific study of kiln site no. 9 at Usanni, one of the earliest royal Kwangju kiln complexes in operation (from the early 15th to the early 16th century), shows that the technological expertise used to produce white ware was inherited from the celadon technology of the Koryo dynasty. The body material, of low Al2O3 and high SiO2 content, is based on porcelain stone. Such a material, with almost no titanium and a low level of iron, was a rediscovery of the white ware material used earlier at the Sori kiln from the 9th century through to the 11th century. Ash continued to be one of the major ingredients of the glaze, and wares were fired in much the same way as the Koryo celadon, in kilns constructed of mud and rocks and in two steps. The Confucian philosophy and aesthetic of frugality and simplicity adopted from the Ming dynasty onwards by the new government acted as the catalyst for the successful ascent of the new technology. [source]


    Estimation of the Production Parameters of Very Large Medieval Bricks from St. Urban, Switzerland

    ARCHAEOMETRY, Issue 1 2002
    S. Wolf
    The aim of the present study is to determine the production technology of a particular type of large medieval brick. The firing temperature and their soak times are estimated using a combination of colour and fabric, as well as mineralogical, microstructural and open porosity analysis. A replication experiment was carried out in order to validate the estimated predictions, and to give a realistic idea of the time needed to dry and fire each large brick. The experiment also suggests the temperature distribution and firing atmosphere in the kiln, as well as providing an estimate of fuel consumption. Analytical results and replication both provide information to assess the production technology, the time parameters and the firing temperatures involved in the production of the medieval bricks of St. Urban. [source]


    Chemical and Mineralogical Alteration of Ceramics from A Late Bronze Age Kiln At Kommos, Crete: the Effect On the Formation of A Reference Group

    ARCHAEOMETRY, Issue 3 2001
    J. Buxeda I Garrigós
    The formation of reference groups comprises an important procedure in chemical provenance studies of archaeological pottery. Material from ancient kilns is thought to be especially suitable for reference groups, as it comprises a definite unit of past production. Pottery from the Late Minoan IA kiln excavated at Kommos, Crete was analysed in order to produce a reference group in this important area of Minoan ceramic production. The samples were characterized by a combination of techniques providing information on the chemistry, mineralogy and microstructure of the ceramic body. Initially, the study was unable to establish, in a straightforward manner, a chemical reference group. Different ceramic pastes and a range of selective alterations and contaminations, affected by variable firing temperatures and burial environment, were shown to be responsible for the compositional variability. Procedures are described to compensate for such alterations and the perturbations in the data that they produce. [source]


    CFD modeling of rotary cement kilns

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2008
    Kaustubh S. Mujumdar
    Abstract Rotary cement kilns are widely used to convert calcineous raw meal into cement clinker, and are key components in the cement industry. In this article, we report a comprehensive computational fluid dynamics (CFD)-based model to capture key transport processes in rotary cement kilns. Separate but coupled computational models were developed for the bed and the freeboard regions of the rotary kiln. The complex swirling airflow produced by kiln burners, coal combustion, gas-phase combustion of volatile matter and radiative heat transfer in the freeboard region were modeled. The clinkerization reactions in the bed region were modeled assuming solids as pseudo fluids. Coating formation in cement kilns (for both bed and freeboard regions) was considered. Appropriate source and sink terms were developed to model transfer of CO2 from the bed to the freeboard region due to calcination reaction in the bed region. The developed bed and freeboard models were coupled by mass and energy communication through common interface. These coupled computational models were able to quite satisfactorily predict the available data from industrial kilns and previously published results. The computational models were also able to capture the intricacies of the burning zones of rotary cement kilns for changing burner-operational parameters like axial to swirl ratio and oxygen enrichment. The developed approach, computational models and simulation results will not only help in developing better understanding of cement kilns but also provide quantitative information about influence of burner design and other design parameters on kiln performance. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]


    Progress in the Modelling of Air Flow Patterns in Softwood Timber Kilns

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2004
    T.A.G. Langrish
    Progress in modelling air flow patterns in timber kilns using computational fluid dynamics (CFD) is reviewed in this work. These simulations are intended to predict the distribution of the flow in the fillet spaces between boards in a hydraulic model of a timber kiln. Here, the flow regime between the boards is transitional between laminar and turbulent flow, with Reynolds numbers of the order of 5000. Running the simulation as a transient calculation has shown few problems with convergence issues, reaching a mass residual of 0.2% of the total inflow after 40 to 100 iterations per time step for time steps of 0.01 s. Grid sensitivity studies have shown that non-uniform grids are necessary because of the sudden changes in flow cross section, and the flow simulations are insensitive to grid refinement for non-uniform grids with more than 300,000 cells. The best agreement between the experimentally-measured flow distributions between fillet spaces and those predicted by the simulation have been achieved for (effective) bulk viscosities between the laminar viscosity for water and ten times that value. This change in viscosity is not very large (less than an order of magnitude), given that effective turbulent viscosities are typically several orders of magnitude greater than laminar ones. This result is consistent with the transitional flows here. The effect of weights above the stack can reduce the degree of non-uniformity in air velocities through the stack, especially when thick weights are used, because the stack may then be separated from the eddy at the top of the plenum chamber. [source]


    Early pyrotechnology in the Near East: Experimental lime-plaster production at the Pre-Pottery Neolithic B site of Kfar HaHoresh, Israel

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2008
    Y. Goren
    A characteristic hallmark of the Pre-Pottery Neolithic B (PPNB) in the southern Levant was the extensive use of lime plaster for architectural and other purposes. Yet no obvious kilns have been identified in archaeological contexts. Here we present details of an experimental pit-kiln modeling lime-plaster production based on observed burnt stone accumulations in pits at the PPNB site of Kfar HaHoresh in the lower Galilee. The experimental kiln was loaded in layers with ,500 kg of limestone (pebbles and stones) and ,1000 kg of fuel (branches and dung). Fired for 24 hours, and reaching a maximum 870°C, the kiln yielded almost 250 kg of quicklime (calcium oxide, CaO). Micromorphological samples, general observations, and scaled plan view drawings made immediately following and nine years after ignition demonstrate that the original shape of the kiln and residual quicklime within and around it rapidly dissipated through bioturbation, trampling by animals, erosion, rain, and exposure to the elements. This could account for the seeming absence of kilns within sites, although they were probably located close to where lime-plaster was applied, given the unstable nature and toxic effects of handling quicklime. Calculations of the manpower and fuel involved indicate that PPNB lime-plaster production may have been less labor intensive and less detrimental to the environment than previously portrayed. © 2008 Wiley Periodicals, Inc. [source]


    Estimating baking temperatures in a Roman pottery kiln by rock magnetic properties: implications of thermochemical alteration on archaeointensity determinations

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2006
    Simo Spassov
    SUMMARY Absolute past geomagnetic field intensity determinations requiring laboratory heating are labourious and the success rate is rather low, mostly because of induced thermochemical magnetic mineral alterations. Archaeomagnetic intensity determinations are mainly limited to displaced ceramics produced in kilns. In this study, the suitability of an in situ baked structure is investigated. Different magnetic properties of baked material taken from the combustion chamber wall and floor of a Roman pottery kiln, with variable colouring, are examined in dependence on the distance to the combustion chamber. The temperature distribution is re-constructed based on rock magnetic experiments after stepwise heating. The rock magnetic temperature estimates agree fairly well with a mathematical heat conduction model demonstrating the penetration of heat into the combustion chamber wall. The rock magnetic results show that blackish- and greyish-coloured kiln parts, that had been in close contact with the fuel, during ancient kiln operation, are not suitable for intensity determinations. Although sufficiently baked, they strongly alter during laboratory heating and new remanence-carrying minerals are formed. The brownish-coloured material at a distance 65,80 mm away from the combustion chamber seems to be most suitable as its magnetic properties remain nearly unchanged during laboratory heating. Rock magnetic and modelled temperature estimates for this material consistently indicate ancient baking temperatures of about 600°C. The model demonstrates that cooling takes longer in the inner parts of the combustion chamber wall. Retarded cooling affects the blocking temperatures and hence the strength of the thermoremanent magnetization. The variability of cooling rates should be taken into account when investigating archaeointensities of specimens cut from large samples, or of samples taken from different parts of a kiln. [source]


    Experimental modelling and intelligent control of a wood-drying kiln

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2001
    Givon Chuen Kee Yan
    Abstract Proper control of the wood-drying kiln is crucial in ensuring satisfactory quality of dried wood and in minimizing drying time. This paper presents the development, implementation, and evaluation of a control system for a lumber drying kiln process incorporating sensory feedback from in-wood moisture content sensors and intelligent control such that the moisture content of lumber will reach and stabilize at the desired set point without operator interference. The drying process is difficult to model and control due to complex dynamic nonlinearities, coupling effects among key variables, and process disturbances caused by the variation of lumber sizes, species, and environmental factors. Through system identification scheme using experimental data and recursive least-squares algorithm for parameter estimation, appropriate models are developed for simulation purpose and controller design. Two different control methodologies are employed and compared: a conventional proportional-integral-derivative (PID) controller and a direct fuzzy logic controller (FLC), and system performance is evaluated through simulations. The developed control system is then implemented in a downscaled industrial kiln located at the Innovation Centre of National Research Council (NRC) of Canada. This experimental set-up is equipped with a variety of sensors, including thermocouples for temperature feedback, an air velocity transmitter for measuring airflow speed in the plenum, relative humidity sensors for measuring the relative humidity inside the kiln, and in-wood moisture content sensors for measuring the moisture content of the wood pieces. For comparison, extensive experimental studies are carried out on-line using the two controllers, and the results are evaluated to tune the controller parameters to achieve good performance in the wood-drying kiln. The combination of conventional control with the intelligent control promises improved performance. The control system developed in this study may be applied in industrial wood-drying kilns, with a clear potential for improved quality and increased speed of drying. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    The Archaeology of the Kelp Industry in the Northern Islands of Ireland

    INTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 2 2006
    W. Forsythe
    The manufacture of kelp in Ireland from the 17th to early 20th centuries provided soda and later iodine for contemporary industries. It was an immensely important element of coastal economies, and notably for island communities, often impoverished and with limited agricultural means. This paper traces the origins and development of the industry in Ireland and examines the evidence for production in the islands off the northern coast. The results of a recent survey of surviving kelp monuments are presented. The form of the monuments, in particular kilns, is considered as well as the role of the industry in island economies. © 2006 The Author [source]


    Application of the self-potential method to archaeological prospection: some case histories

    ARCHAEOLOGICAL PROSPECTION, Issue 2 2004
    M. G. DrahorArticle first published online: 12 MAY 200
    Abstract The self-potential (SP) method is very rarely used in archaeological prospection because related phenomena are not very well known. The aim of this study is to discuss the different SP phenomena that might be observed at archaeological sites, and therefore the SP method was applied at different archaeological sites in Anatolia (Turkey), such as Acemhöyük, Amorium, Burgaz and Ulucakhöyük archaeological areas and the Sinop amphorae workshop site. These studies indicated that SP anomalies existed over both burned or unburned materials at archaeological sites, such as walls, pits, kilns, etc. Furthermore, SP anomalies were also found over areas of complex soil distribution and visible physical changes on the surface. Other kinds of SP anomalies were also observed in those archaeological structures located very close to the coastline. These results were confirmed by archaeological excavations, which were carried out after geophysical surveys in the areas studied. All the studies supported that electrokinetic and electrochemical potentials might be the main cause of SP anomalies in the buried archaeological structures. The SP data collected with the gradient and total measurement techniques were processed by forward and inversion methods, and the main SP parameters (h, Q and x0) were determined. In addition, the SP results were compared with other applied geophysical methods such as resistivity and magnetic. Copyright © 2004 John Wiley & Sons, Ltd. [source]


    Application of magnetic and spectrometry methods in the detection of human activity in soils: a case study at the archaeological site of Kitros (Northern Greece)

    ARCHAEOLOGICAL PROSPECTION, Issue 3 2001
    E. V. Aidona
    Abstract In the present study the archaeological site of (Louloudies,Kitros) (northern Greece) is investigated by the use of magnetic and spectrometry geophysical methods. Soil samples were collected from several trenches within the archaeological site, as well as from radial traverses around kilns, which were used for glass production. Moreover, samples were collected from a long traverse, starting from the middle of the archaeological site and extending outside the site, in order to identify the limits of the settlement. Measurements were successful in identifying the different occupation levels and the boundaries of the archaeological site. High values of magnetic susceptibility and iron oxide content correlated well with the periods of intense human activity. Around the kilns, the mean values of the magnetic susceptibility indicated the effect of the fire mechanism in the surrounding area and gave some first evidence concerning the use of the kilns. Comparison of the magnetic and chemical properties of the anthropogenic soils suggests that their enhancement may be used as an index for locating areas and features of archaeological interest. Additionally, archaeomagnetic data have been obtained from a pottery and a glass kiln of the site. The magnetic directions (D = 355°, I = 62°, a95 = 3.6 and D = 356°, I = 51°, a95 = 2.3) were correlated to the reference curves compiled for Bulgaria and showed a satisfactory consistency for the declination, but the inclination values of the recorded magnetic field were divergent by about 10°. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    LEAD ISOTOPE ANALYSIS OF TANG SANCAI POTTERY GLAZES FROM GONGYI KILN, HENAN PROVINCE AND HUANGBAO KILN, SHAANXI PROVINCE

    ARCHAEOMETRY, Issue 4 2010
    J. F. CUI
    Through the use of MC,ICP,MS, this study analyses the lead isotope ratios of 19 Tang Sancai pottery glazes unearthed from the Gongyi and Huangbao kiln sites. According to their different lead isotope ratios, the two kilns can be grouped separately. The research also suggests that the Gongyi and Huangbao kilns are independent production centres of Tang Sancai in the Tang Dynasty. The data from the Huangbao kiln indicates that the lead in the glazes originates from the Northern China geochemical province, while the data from Gongyi kiln suggests its source as the Yangtze geochemical province. Furthermore, the results obtained for the Tang Sancai pottery indicate that the lead sources for glaze making of these two kilns were very consistent, which suggests that lead isotope analysis could be a helpful method to identify the kilns producing Tang Sancai artefacts. [source]