ADVANTAGES AND USE OF A CO2 METER ON A FORCED DOWNDRAFT PERIODIC KILN AS TO TEMPERATURE DISTRIBUTION1

Notes on forced downdraft system used on dry-pressed electrical porcelain fired to cone 12 flat are discussed. The type and general construction of the kiln, heat distribution, fuel used per firing, and the use of the CO₂ meter for adjusting the draft for various conditions to get uniformly fired kilns, both as to time of firing and appearance of ware, are given.     

NOTES ON FIRING TERRA COTTA1

Some notes are given on the firing behavior of a 14-foot diameter muffle type terra cotta kiln, using coal as a fuel. The need of more data on periodic fired kilns in all branches of the ceramic field is stressed.     

Evolution of fluorine emissions during the fast firing of ceramic tile

The present paper examines the emission–adsorption phenomena of fluorine compounds in various ceramic tile body compositions with different fluorine and calcium contents, processed by fast firing cycles in an electric laboratory batch kiln and in continuous fast-cycle industrial combustion kilns (roller kilns). In the roller kilns, fluorine emission was monitored by analysing the fluorine content in both solid and gas samples throughout the kilns.It was found that fluorine emission during firing in air atmosphere in the laboratory batch kiln began at temperatures above 800 °C and increased progressively up to peak firing temperature. In the roller kilns, however, the emissions started at lower temperatures and decreased in certain kiln zones. This decrease indicates that there are regions in these kilns in which fluorine is adsorbed rather than emitted by the material being processed.A fluorine adsorption process is thus shown to occur in the preheating stage in the roller kilns, despite the rapid heating rate. However, encouraging this adsorption process in order to foster the formation of crystalline phases is ineffective in abating fluorine emissions when ceramic tiles are fired at peak temperatures exceeding 1100 °C.     

Firing lightweight Dinas in a tunnel-type kiln

Conclusions The best type of stacking has been ascertained for lightweight dinas on tunnel-type kiln cars.The dinas can be fired in tunnel-type kilns together with ordinary dinas without altering the firing conditions.The lightweight dinas fired in the tunnel-type kilns included the larger types PM-17 and PM-20, so there is no doubt that standard size lightweight dinas can also be fired in these kilns.The satisfactory results of the experiments have enabled the plant to begin firing this dinas in tunnel-type kilns.     

VALIDATION OF A DYNAMIC MODEL FOR A DEHUMIDIFIER WOOD DRYING KILN

ABSTRACT

The validation of a dehumidifier wood drying kiln model established previously has been conducted by using the performance data for a commercial scale kiln. The good agreement between the modelled and measured performance results shows that the model can be used for the design and analysis of dehumidifier wood drying kilns.     

PRODUCER GAS FOR BURNING REFRACTORIES1

History of installations in the United States of producer gas for burning fire brick. Causes of failure or abandonment of producer gas firing. Continuous regenerative kiln necessary for successful burning at high temperatures with producer gas. The compartment kiln, fired with producer gas, best adapted for general refractories. Advantages of the compartment kiln over the car tunnel kiln. Essential features of continuous kilns for the successful burning of refractories. Special features of gas producers for ceramic kilns. Temperatures from producer gas. Economy of producer gas as compared with natural gas, oil and powdered coal. Investigation of designs and methods of operating gas producers.     

陶瓷隧道窑热耗的计算机模拟

介绍陶瓷燃料隧道窑热耗数学模型的建立及计算机模拟的方法.将计算机模拟结果与实测数据相比较,表明建立的热耗数学模型是基本符合实际的,可以应用于对陶瓷燃料隧道窑热耗的各种因素的定量分析,寻求节能的正确途径.     

Low firing temperature ceramic for microcircuit substrates

Methods for fabricating substrates based on low-temperature (firing temperature below 1000°C) ceramic, fired together with a deposited metal coating, are examined. Materials which are promising for use as low-temperature simultaneously fired ceramic (LSC) in the systems B₂O₃-CaO-SiO₂ and B₂O₃-CaO-Al₃O₃ are proposed.     

CLAY SEWERPIPE MANUFACTURE1 VI. Heat-Balance Determinations

Heat-balance determinations were conducted on a number of sewerpipe kilns and the kiln efficiencies were found to vary from 14.97% to 29.03%. The method of calculating the heat balance is described in detail. Kiln efficiencies for individual periods range higher for the second period in most cases with some of the kilns reaching upward of 40% efficiency. In general as the kiln reaches higher temperatures the kiln efficiency decreases due to increasing stack and kiln structure losses. In all, thirty-four kiln tests were conducted in six plants in various sections of the country, in twenty-six of which heat-balance calculations were made, the remainder being auxiliary tests giving only general operating data such as tonnage of ware, fuel consumption, temperature schedule, and ware analysis.     

陶瓷窑炉墙体新型砌筑方法与节能

辊道窑是陶瓷工业的新型窑炉，其具有很多优点。有利于实现烧成工序的机械化与自动化，是快速烧成较理想的窑炉，但由于辊子长度的限制。窑墙结构较薄；但无论窑炉多先进，耗热大还是陶瓷窑炉的重要课题。笔者曾对窑墙散热计算时发现。在不改变耐火材料及保温材料的厚度及种类。只改变耐火材料及保温材料的砌筑方法，得到不同保温性能，从而可进一步探讨改进辊道窑窑墙结构的方案。     

SILLIMANITE KILN REFRACTORIES MADE FROM AN ANDALUSITE BASE1

Some andalusite refractories are high in transverse strength. Bars 12 inches long, 2 inches wide, and 1/2 inch thick tested across an 11-inch span supported a 45-pound load with 13/32-inch sag at cone 16^1/4 and a 1/2-pound load at cone 34 down with 1/16-inch sag. A standard 9-inch brick tested under a load of 50 pounds per square inch at 1525°C showed no deformation. They are relatively constant in volume, are not affected by kiln gases, and tend to improve rather than to deteriorate under continued heating owing to the formation of an increased amount of mullite. Andalusite saggers used at cone 12 are estimated to have stood 180 cycles and are still in good condition. Saggers in continuous use at cone 16^1/4 have an estimated average age of 1^1/2 years and many are four years old. The andalusite lining of a periodic kiln being fired regularly at 3000 to 3200°F is still serviceable after 110 firings. Cars built of andalusite refractories have given five years of continuous service in tunnel kilns operating at cone 16^1/4, whereas cars built of fireclay refractories were unfit for use after three to four months. Side walls, damper boxes, expansion sleeves, and flame shields of Dressler tunnel kilns operating at cone 16^1/4 have proved satisfactory.     

EFFECT OF VARIOUS GASEOUS ATMOSPHERES ON THE VITRIFICATION OF CERAMIC BODIES*

Various types of ceramic bodies were fired in atmospheres of O₂, N₂, CO₂, H₂, and H₂. A marked increase in the rate of vitrification occurred when bodies containing feldspar were fired in an atmosphere of H₂O. This effcct was explained on the basis of a feldspar-water eutectic.     

Data-driven research on chemical features of Jingdezhen and Longquan celadon by energy dispersive X-ray fluorescence

The energy dispersive X-ray fluorescence (EDXRF) is used to determine the chemical composition of celadon body and glaze in Longquan kiln (at Dayao County) and Jingdezhen kiln. Forty typical shards in four cultural eras were selected to investigate the raw materials and firing technology. Random forests, a relatively new statistical technique, has been adopted to identify chemical elements that are strongest explanatory variables to classify samples into different cultural eras and kilns. The results indicated that the contents of Na₂O, Fe₂O₃, TiO₂, SiO₂ and CaO vary in celadon bodies from Longquan and Jingdezhen, which implies that local clay was used to manufacture celadon bodies in Jingdezhen kiln. By comparing the chemical composition in glaze, we find that the chemical elements and firing technology of Jingdezhen kiln are very similar to those in Longquan kiln, especially for Ming dynasty. This study reveals the inheritance between Jingdezhen kiln and Longquan kiln, and explains the differences between two kilns.     

Experimental investigation and mathematical modelling of wood combustion in a moving grate boiler

The use of biomass to generate energy offers significant environmental advantages for the reduction in emissions of greenhouse gases. The main objective of this study was to investigate the performance of a small scale biomass heating plant: i.e. combustion characteristics and emissions. An extensive series of experimental tests was carried out at a small scale residential biomass heating plant i.e. wood chip fired boiler. The concentrations of CO, NO_x, particulate matter in the flue gas were measured. In addition, mathematical modelling work using FLIC and FLUENT codes was carried out in order to simulate the overall performance of the wood fired heating system. Results showed that pollutant emissions from the boiler were within the relative emission limits. Mass concentration of CO emission was 550-1600 mg/m³ (10% O₂). NO_x concentration in the flue gas from the wood chips combustion varied slightly between 28 and 60 ppmv. Mass concentration of PM₁₀ in the flue gas was 205 mg/m³ (10% O₂) The modelling results showed that most of the fuel was burnt inside the furnace and little CO was released from the system due to the high flue gas temperature in the furnace. The injection of the secondary air provided adequate mixing and favourable combustion conditions in the over-bed chamber in the wood chips fired boiler. This study has shown that the use of wood heating system result in much lower CO₂ emissions than from a fossil fuel e.g. coal fired heating system.     

DYNAMIC MODELLING OF A DEHUMIDIFIER WOOD DRYING KILN

ABSTRACT

For the optimum design and operating information of heat pump dehu-midifier wood drying kilns, a comprehensive kiln model has been developed, which solves the fundamental balance equations for the whole system. The model is suitable for analysing the influence of design and control variables on the performance of the system as a whole. To illustrate the application of the model, the operation of a dehumidifier wood drying kiln has been analysed under typical operating conditions and kiln controls. The drying performance has been discussed in detail.     

DESIGN FOR LUMBER DRY KILN USING SOLAR/WOOD ENERGY IN TROPICAL LATITUDES

Developing countries with a timber resource that can be manufactured into finished products either for local use or export often lack the capital to build high-cost dry kilns. Many of these countries are in the tropics where solar radiation and ambient temperatures are high. The low-cost solar/wood energy lumber dry kiln described in this report was designed and tested for such countries where solar dry kilns can be built and operated at low cost.

The design is for a 14-m"6,000-fbm capacity kiln having an insulated drying compartment, an external horizontal solar collector, and a furnace room containing a wood burner. Capacities larger or smaller than 6,000 fbm are also possible. This design allows collector and wood burner sizing to match the energy demands of the dryer. The design also incorporates low-cost controls that allow unattended drying when operated as a solar-only dryer. Manual firing is necessary when the wood-burning system is supplying the energy.     

基于网络的陶瓷窑炉"用户群"技术支撑平台的初步研究

针对国内众多陶瓷窑炉用户对燃烧节能系统及其优化控制技术的需求,以及部分企业窑炉使用维护不方便等问题,提出了以陶瓷窑炉节能及其优化控制系统为基础的,基于网络的面向陶瓷窑炉“用户群”的技术支撑平台,以形成窑炉制造者和用户双方相互交融的技术链,以便实现陶瓷窑炉节能及其优化控制技术的产业化。     

基于网络的陶瓷窑炉"用户群"技术支撑平台的初步研究

针对国内众多陶瓷窑炉用户对燃烧节能系统及其优化控制技术的需求,以及部分企业窑炉使用维护不方便等问题,提出了以陶瓷窑炉节能及其优化控制系统为基础的,基于网络的面向陶瓷窑炉“用户群”的技术支撑平台,以形成窑炉制造者和用户双方相互交融的技术链,以便实现陶瓷窑炉节能及其优化控制技术的产业化。     

Sintering of magnesia refractories through the formation of periclase–forsterite–spinel phases

Effect of calcined kaolin additions on sinterability of dead-burned magnesia was studied through additions of Egyptian kaolin. Five batches containing powders of 100/0, 90/10, 80/20, 70/30 and 60/40 magnesia/kaolin, respectively, were mixed, dried and fired up to 1550 °C for 4 h. Their physical (bulk density and apparent porosity), mechanical (cold crushing strength) as well as refractory (thermal shock resistance and refractoriness under load) properties were tested according to the International Standard Specifications. The phase compositions of the fired batches were investigated using X-ray diffraction as well as scanning electron microscope to illustrate the effect of the different developed phases on the above properties compared with the main magnesia source itself. Generally, samples containing 10–20 wt.% kaolin are characterized by their high sintering, mechanical and refractory properties, so they are recommended for use as a lining for different parts of steel furnaces as well as heating zone of cement rotary kilns. Samples containing 30–40 wt.% kaolin with lower refractory properties can be used in the heat exchangers or as kiln furniture in ceramic industries.