High-temperature Facilities Research Articles

Heat Illness Prevention in the Outdoor Workplace

In the construction industry a large amount of work is completed outdoors where the sun may expose or heat up rooms that can affect employees while working. This research will recognize how companies combat with heat illness and heat prevention methods to keep employees healthy and safe while working in high temperatures. Each year in the United States thousands of employees fall ill to heat related illnesses, stem from heat rash to heat stroke, which can be fatal, if not treated properly. Research will examine what standards are required by the Occupational Safety & Health Administration (OSHA) and how many participants companies currently abide by those standards. Every day that employees who work outdoors or in high temperature facilities go without proper training and education about heat stress, the number of cases will rise and more will become ill to heat related complications. This study will give prevention methods to help keep American workers safe.

Energy Balances the Process Thermal Decomposition Methane in Cooling Conditions High-Temperature Technological Installations

A mathematical model the energy balances the process thermal decomposition methane under cooling conditions high-temperature installations is proposed. The model under study allows us to evaluate the possibility using regenerative heat use, in order to reduce heat losses through the fence a high-temperature installation by utilizing the heat of the liquid coolant, allowing to increase the productivity the high-temperature process. Natural gas as an energy carrier has a lot advantages and in comparison with other types fuel can be fully used, since it is easy to organize complete combustion with minimal heat loss. It is worth noting that natural gas does not contain ballast and harmful impurities, it also has a high calorific value and high temperatures develop during combustion. All high-temperature installations have the main task ensuring the continuity the process with minimal fuel consumption, using energy from both primary and secondary energy resources (SER). Under pyrolysis conditions, methane is most thermally stable, since thermal degradation methane is thermodynamically possible at temperatures above 560°C. However, when methane reaches significant speeds, it decomposes at temperatures about 900°C, and at temperatures above 1400°C it completely decomposes into carbon and hydrogen. The purpose calculations the mathematical model is to determine the heat transfer coefficient and the temperature field methane heating inside a single tube under specified boundary conditions and thermal parameter the system under consideration. Solving this problem will increase the energy efficiency the high-temperature process. Also, the input the calculations was the analysis of existing apparatus for the pyrolysis methane with liquid coolant for steelmaking, is determined depending on the heat transfer regime gas flow (Re⩽105), the number Nusselt, the amount heat received and given in the decomposition process, the temperature heating natural gas and represented by a graph fraction carbon and hydrogen inlet the thermal decomposition in terms the cooling high-temperature facilities.

Thermography of inner surfaces of high-temperature industrial facilities

Thermography of inner surfaces of high-temperature facilities is an important task of industrial non-destructive testing. Existing methods operating in the visible wavelength range require the spectral scanning during the image acquisition to determine the distribution of temperature across the field of view. The infrared imaging techniques require specific lenses and image sensors. In this paper, we propose a method for remote determination of the spatial temperature distribution that is not limited by the mentioned restrictions. It is based on the use of an image sensor with a mosaic spectral filter array installed on it. This paper presents the layout of the prototype and the possibility of its practical application demonstrated in laboratory conditions.

Influence of Beam Offset on Dissimilar Laser Welding of Molybdenum to Titanium.

Dissimilar joining of molybdenum (Mo) to titanium (Ti) is of great significance to the design and fabrication of high-temperature facilities. However, few reports were found about fusion joining of these two metals. The objective of this paper is to assess the feasibility of laser beam welding (LBW) of 2 mm-thick molybdenum and titanium. The effects of laser beam offset on the laser dissimilar joint of pure molybdenum to pure titanium were analyzed in terms of microstructure, chemical composition, microhardness, and tensile behavior. The results showed that the weld appearance improved with the increase of the offset. The fusion zone was strengthened because of the solid solution of these two elements. The mechanical properties of samples increased firstly and then decreased with the increasing of offset. When the laser beam irradiated on the titanium plate and the center of the laser spot was 0.5 mm away from the Mo/Ti interface, the joint performed the highest tensile strength, which was about 70% that of titanium base metal. LBW was demonstrated to be a promising method to join dissimilar Mo/Ti joint.

Investigations of the thermophysical properties of monocrystalline tungsten

Monocrystalline tungsten and its alloys are of interest in the design and manufacture of high temperature facilities operating at high (up to 2500 °C) temperatures in vacuum under mechanical loads. This paper demonstrates advantages of using monocrystalline tungsten as a structural material in high-tech industry in comparison with polycrystalline materials. The results of comparative studies of the thermophysical properties of polycrystalline and monocrystalline tungsten 4% tantalum alloy are presented. It is shown that monocrystalline tungsten based materials are more suitable for use under high temperatures and high mechanical stresses than polycrystalline. Use of monocrystalline tungsten as a structural material makes it possible to prolong the service life of modern technical facilities.

Controlling Factors of Localized Corrosion in Boiler Combustion Gas Environments

Localized corrosion (LC) sometimes appears in boiler tubes exposed in severely corrosive combustion gases including Cl, S and O, but prediction and on-site maintenance of LC is actually difficult in many cases. Therefore understanding the cause of LC is considered to be important to maintain safety services and estimate lifetime in high temperature facilities. This LC occurs due to formation of partially different corrosive conditions due to fuels, condition of combustion, designing of boilers, and materials. In this paper, investigation results of macroscopic LC and influenced factors formed in actual boilers were described with the four cases of fossil fuel, biomass and WTE boilers, and also described against any coatings. Mechanisms of each LC were considered individually by using cut-off samples of damaged tubes, detailed analyses of corrosive environments and results of laboratory tests. From these considerations, protective oxide layers and not only static factors but also dynamic factors arising in operated conditions such as temperature and composition fluctuations were concluded to be important for the accurate lifetime evaluations of tube materials and coatings.

Metallogenic mechanisms of super-large Cu and Au deposits in the Dexing region and simulating experiments

Based on the results of previous studies and under the direction of the theory of “ore deposit genesis”, the authors made use of high temperature and high pressure experimental facilities and conditions at the Tectono-geochemistry Research Room under the State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, and put the focus on the multi-source of tectonically controlling ore-forming materials, the characteristics of multi-stage and multi-episode hydrothermal activities and mineralization and the characteristics of multi-genesis and multi-ore deposition so as to shed light on the metallogenic mechanisms of super-large Cu and Au deposits. In addition simulating experiments were made on multi-stage and multi-episode tectonic activities and rock and ore deformation, multi-stage and multi-episode tectonic activities and mobilization and migration of ore-forming materials, and multi-stage and multi-episode tectonic activities and superimposition and enrichment of ore-forming materials. The experimental results showed that under the action of multi-stage and multi-episode tectonic stress the deformation and fragmentation of not only rocks and ores have been intensified, and but also the ore-forming materials originally disbursed in the rocks and ores have been mobilized and migrated and superimposed and enriched. The experimental results also provided the scientific experimental data and grounds for deep-going research on the rules of metallogenesis and geneses of super-large ore deposits in the Dexing region, Jiangxi Province.

Phase- and structure-formation processes during self-propagating high-temperature synthesis in the system Al – MgCO3 – SiO2 – C

Phase and structure formation processes occurring in the system Al – MgCO3 – SiO2 in the course of selfpropagating high-temperature synthesis are examined. The dependences of the structure and the phase composition of the composite materials formed on the ratio of the initial components are determined. It is shown that self-propagating high-temperature synthesis can be used to produce ceramic composite materials based on the spinel and silicon carbide phases. An effective method of obtaining composite materials is self-propagating high-temperature synthesis (SHS). SHS technology is a powder technology but it differs fundamentally from other powder technologies used in metallurgy by the fact that to realize synthesis powders are combusted and not heated in high-temperature facilities. The synthesis process proceeds by means of its own release of heat as a result of the interaction between the components of the initial mixture with valuable condensed products being formed, which makes it possible to decrease costs and reduce the energy consumption for production and, therefore, decrease prime costs [1]. Phase formation in the process of combustion of powdered mixtures occurs directly in the reaction volume, and the crystalline compounds formed grow into particles of other compounds. In the process it becomes possible to obtain composite crystalline phases, which is difficult to do under ordinary conditions. An example is a composition consisting of spinel and silicon carbide. Aluminomagnesia spinel MgO Al 2 O 3 is a ceramic material with adequate mechanical strength and good corrosion and radiation resistance; it is widely used in metallurgy, machine building, instrument building, the chemical industry as linings for inductors and electric resistance furnaces, filters for melts, high-temperature electric insulators, and articles for other purposes. Spinel ceramic finds wide applications in the manufacture of protective cases for thermocouples and crucibles for melting metals. Aluminomagnesia spinel is also a promising refractory material, used in heating equipment in its own form and with the addition of magnesia refractories during fabrication [2, 3]. The kinetic difficulties in the synthesis of spinel via the reaction

An interactive approach to creep behavior modeling

Design and inspection of components used in high-temperature facilities, as well as evaluation of their lifespan requires detailed knowledge of creep behavior of the employed materials. Over the past decades, numerous phenomenological creep equations, describing creep strain dependency of physical quantities like time, stress or temperature via a set of parameters, have been developed. This paper deals with a novel approach of creep model parameter identification by an interactive graphical computer-based application aimed to significantly reduce evaluation time by automating necessary calculations as far as possible while, at the same time, providing a maximum of adjusting possibilities to program users—typically, materials experts. During evaluation, intermediate results are instantly displayed numerically and graphically. Verification purpose creep experiments on gradient specimens, as well as relaxation experiments, demonstrate the quality of this approach.

High-Temperature Fixed-Point Facilities for Improved Thermocouple Calibration—Euromet Project 857

LNE, NPL, and PTB decided in 2005 to join their research efforts in the framework of Euromet Project 857 with the aim of reducing the calibration uncertainty of noble metal and other high-temperature thermocouples by at least a factor of two. This ambitious target will be met through the development and implementation of robust high-temperature fixed points based on metal–carbon eutectic technology. The Euromet project is structured around five work packages and ensures good and efficient cooperation between the partners to meet the objectives within the project timeframe of four years. Furthermore, a formal cooperative research agreement has been established with the National Metrology Institute of Japan (NMIJ) to demonstrate, on a worldwide basis, that this new method is a significant improvement over current calibration methods. In summary, the project consists of (a) the development of sets of cells at the cobalt–carbon eutectic point (1324◦C) and palladium–carbon eutectic point (1492◦C) and (b) the construction of platinum/palladium (Pt/Pd) thermocouples carefully stabilized for use to these temperatures. Supplementary research to be undertaken as part of this project is the improvement of fixed-point construction and realization capabilities through high-temperature furnaces with low thermal gradients. This paper describes the European project and gives an overview of current progress.

Analysis of the Temperature and Pressure Dependence of the 129Xe NMR Chemical Shift and Signal Intensity for the Derivation of Basic Parameters of Adsorption as Applied to Zeolite ZSM-5

Temperature and pressure dependences of the 129Xe NMR chemical shift and the signal intensity have been investigated using ZSM-5 as an adsorbent under routine conditions without using any high-pressure or especially high-temperature facilities. The use of a rigorously shielded system and a calibration sample for the signal intensity was found to be valuable to obtain reliable data about the chemical shift and the signal intensity. The 129Xe NMR data obtained between 0.05 and 1.5 atm and from 24 to 80 degrees C were analyzed based on the Dubinin-Radushkevich equation as well as the Langmuir type equation. In both analyses, chemical shift data succeeded only partially in providing the profile of adsorption, such as energetic aspects, surface area, saturated amount of Xe adsorption and specific parameters of 129Xe chemical shift. It was shown that the reliable total analysis was achieved when the chemical shift data were used together with the intensity data. Such an analysis of the chemical shift data, aided by the intensity data, will be useful in performing nano-material analysis on 129Xe NMR without invoking the traditional methodology of gravimetric or volumetric adsorption experiments.

Investigation of weld joints in high temperature facilities. Examples of creep damage (Type 4) and evaluation methods

(2003). Investigation of weld joints in high temperature facilities. Examples of creep damage (Type 4) and evaluation methods. Welding International: Vol. 17, No. 3, pp. 182-188.

Standardization of Surface Replication Procedures for Life Assessment of High Temperature Facilities

Surface replication is playing an important role in the assessment of creep damage and remaining life of high temperature components. As the replication procedures, however, have not been standardized in domestic industry, its standardization is proposed in this study. For this purpose, the 2.25Cr-IMo steel was heat treated(5 min at 1,300 0C and oil quenched) to produce a simulated HAZ microstructure, and crept in air at 575 0C and under 120 MPa to produce artificial cavities. Then, the effect of surface preparation procedures on the quality of replicas was investigated using this sample. As a result, it was demonstrated that the presence of cavities may be observed readily or missed depending on the surface preparation procedures followed. Therefore it is essential to repeat three polishing/etching cycles at least in order to reveal cavitation damage accurately, even though it may be tedious or time-consuming.

Protecting pressure gauges with grease in high temperature facilities

The thermal protection of pressure gauges used in shock tubes has to avoid inducing losses in response time and accuracy. A study was undertaken to this purpose, and a procedure for mounting and covering the gauges with a protection layer of grease has been developed. Results up to date show satisfactory behaviour.

Development of a National Toxic Waste Disposal Facility in the State of Bahrain

Bahrain is an example of a small, newly industrialized country with a limited range of both heavy and light industry. A survey of toxic and hazardous wastes identified only four significant streams of bulk solid wastes and three of oily wastes. In these circumstances, the establishment of a conventional centralized treatment facility complete with high-temperature incinerator and chemical treatment facilities could not be justified. This paper presents the results of a study aimed at developing a national toxic waste disposal facility appropriate to the specific needs and circumstances of Bahrain. As such, it will be of interest to other newly industrialized countries. A national disposal facility has been developed at a remote desert site. A hydrogeological site investigation showed that the site is, effectively, impermeable. Nevertheless, design of the land disposal facility focussed on the desirability of preventing rainfall infiltration during occasional flash floods. Oily wastes are being utilised to "seal" both the base of the site and the completed surface.