Gas Flame Heating Research Articles

Modeling of the process of heating of chip‑powder dispersions of ferrous metals in the pass‑through muffle furnace of hot briquetting. Message 2

The simulation of the chip heating process in the zones of gas-flame and induction heating of a continuous muffle furnace has been carried out. The mechanisms of heat transfer (conductive, convective, radiative) that have a conjugated character are considered in the approximation of interpenetrating continuums in the absence of any noticeable influence of filtration processes under conditions of a highly porous chip medium. As a result of the analysis of heat and mass transfer in the porous chip body and the working space of the furnace, a system of equations was obtained for calculating temperature and concentration fields and fields of thermal radiation intensity depending on the specified furnace productivity, natural gas consumption, and oil concentration in the coolant. The system of equations, which is a model of heat and mass transfer processes, is closed and allows us to solve the problem posed – to determine the heating temperature of the chips at the exit from the gas-flame heating zone, the composition and residual content of the liquid phase in it, and also to find the optimal height and temperature of the inductor muffle in induction heating zone, dimensions and electrical parameters of the inductor.

Investigations of thermal barrier coatings of turbine parts using gas flame heating

The development of methods for the calculated and experimental investigations thermal barrier coatings and thermal state of gas-turbine engine parts with a thermal barrier coatings is actual work. The gas flame heating was demonstrated to be effectively used during investigations of a thermal ceramic barrier coatings and thermal state of such gas-turbine engine parts with a TBC as the cooled turbine blades and vanes and combustion liner components. The gas-flame heating is considered to be preferable when investigating the gas-turbine engine parts with a TBC in the special cases when both the convective and radiant components of thermal flow are of great importance. The small-size rig with gas-flame flow made it possible to conduct the comparison investigations with the purpose of evaluating the efficiency of thermal protection of the ceramic deposited thermal barrier coatings on APS and EB techniques. The developed design-experiment method was introduced in bench tests of turbine blades and combustion liner components of gas turbine engines.

Method, Technology and Equipment for in Depth Surface Hardening

The present work deals with a new method, technology and equipment developed for “in depth surface hardening” of large rotary details and tools, made of constructional, carbon, alloyed or low-alloyed tool steels. According to the technical requirements the details and tools have to possess hardened layer with specific shape, depth in the range 20-35mm and surface hardness of 35-62 HRC. The “in-depth hardening” was performed by quenching and self-tempering. Preliminary volume heating and depth regulated local surface adjustable gas-flame heating were used. The gasflame heating was realized by gas-flame burners (CH4+O2) located near the details’ periphery, depending on the shape and depth of the hardened layer. The burners’ power and heating time were adjustable. The cooling was performed by showers located near the details’ periphery also depending on the shape of the hardened layer. Water or polymer water solution was used as cooling media and its capacity was adjusted in the beginning. Due to the heat accumulated during the preliminary heating and the heating up to the quenching temperature of the surface layer, after stopping the cooling, subsequent self-tempering was applied. All of the equipment for realizing the whole hardening cycle, temperature and time control and parameters of heating and cooling was developed. Series of different details were hardened: traversing wheels and gears, forming rolls, rolling disks etc., made of construction and tool steels. The hardened layers obtained were with specific shape, surface hardness in the range of 35-60HRC and depth of the hardened layer of 15- 25mm.

Investigations of thermomechanical fatigue for optimization of design and production process solutions for gas-turbine engine parts

A technique for thermomechanical fatigue of gas-turbine engine parts is discussed. It is shown that induction heating at a frequency of about 400 kHz is suitable for tests of parts with thermal barrier coatings (TBC). For thermocyclic tests at conditions when the radiant component of total thermal flow is significant, a rig with gas-flame heating has been developed. Some results of the tests are presented.

Equipment and technology for volume heat treatment with gas flame heating of large pressure vessels in assembling conditions

Equipment and technology for volume heat treatment with gas flame heating of large pressure vessels in assembling conditions

Nondestructive evaluation of weld defects by infrared thermography : Satonaka, S.; Ohba, H.; Shinozaki, K. Proceedings of the 14th International Conference on Offshore Mechanics and Arctic Engineering, Vol. 3 Copenhagen (Denmark), 18–22 Jun. 1995 pp. 305–312. American Society of Mechanical Engineers (1995). ISBN 0791813096

In order to clarify the applicability of infrared thermography to the nondestructive evaluation of weld defects, an infrared measurement was conducted on the welds with various artificial defects. Two heating methods, a moving gas flame and a Joule effect by electric current flow, were used for the fast and large area inspection with readily interpretable images of defects. Finite element analysis was also used for the theoretical analyses of beat conduction and electric current flow, together with the development of imaging technique for the evaluation of the shape and size of defects. As the results of infrared measurements and theoretical analyses, the selection of heating method and the acquisition of infrared images were important for the clear image and precise measurement of weld defects. As for the clear images, the Joule effect heating was useful for the detection of open-to-the-surface defects, while the moving gas flame heating was available to the inner defect parallel to the surface. It was also clarified that the types of defects were identified by the distribution of high and low temperature regions. In the measurement of defect size, defect edges were evaluated by the positions with maximum temperature gradient in the moving gas flame heating,more » and with minimum second derivative of temperature in the Joule effect heating. The effective images for the precise measurement of defect size were obtained from the ones immediately after current flow in the Joule effect heating, and just before the arrival of gas flame beneath the defect.« less

Mirror Heaters for High Temperature X-Ray Diffraction

For the generation of high temperatures in X-ray and neutron diffraction experiments various techniques such as resistance heating, radiation heating, induction heating and gas flame heating have been applied (Aldebert, 1984). Mirror heaters usually employ some kind of focussing geometry to concentrate the radiation emanating from the heating element onto the sample: Two large parabolic mirrors focussing heat radiation from a carbon arc were used by Stecura (1968) to reach sample temperatures up to 1700°C. Hubert et al. (1974) used radiation from a short arc xenon lamp focussed by two parabolical mirrors to reach sample temperatures of 3200°C.

単結晶X線回折実験用ガス炎加熱装置と温度測定方法

Gas-flame heating apparatus for X-ray diffraction studies designed by Yamanaka, Takeuchi and Sadanaga (1981) consists of gas flow controller and microburner set on the stand and provides temperatures higher than 2000°C. Control of the temperature of the sample is carried out by varying the mixing ratio of propane, oxygen and nitrogen gases. The last gas plays a role to regulate the heating temperature and to suppress a fluctuation of the gas-flame especially at low temperatures. It has been demanded to improve the microburner for a more applicable usage for the single-crystal X-ray diffraction studies. A newly devised heating system is composed of a joint assembly of gas-flame and electric resistance heater. Since the assembly is set on the χ-circle of a four-circle X-ray diffractometer, measurement of the diffraction intensities can be made throughout the same samplesetting from room temperature to high temperatures up to 2500°C and can be conducted at more stable and highly desired temperatures. The measurement of the sample-temperatures higher than 1500°C is carried out by a thermocouple of Pt-Rh (20-40%) or Ir-Rh (40%) and an optical pyrometer. For the precise temperature measurement during the collection of intensity data, the sample is mounted on the thermocouple attached to the goniometer head. The thermoelectric current is guided to the regulator and recorder through a ring terminal fixed to the goniometer.

On-site thermal treatment of chemical and petroleum equipment

Four on-site thermal treatments are recommended to reduce the manufacturing time of chemical and petroleum equipment. First, heating by panel heater of the annular section of the weld, or temper of the annular seam. Properly treated metal plates, cotton-ceramic insulation, and asbestos mats are recommended. Second, gas flame heating by small size units for local heating during minor repairs. This method has two drawbacks: high heat loss, and uneven heating. Third, which is the most advantageous method, heating by a heat-transfer agent admitted into the inner cavity of the unit. Finally, induction heating of annular seams by means of the high frequency unit as given.

Gas-flame heating equipment providing temperatures up to 2600 K for the four-circle diffractometer

Gas-flame specimen-heating equipment has been designed and constructed for structural investigations of materials which are not chemically affected by exposure to the combustion gas. The heating equipment is attachable to any standard four-circle diffractometer, preserving all the functions of the diffractometer, and provides specimen temperatures up to 2600 K. The ventilation of the hot exhaust gas and the use of a small flame prevent the elevation of temperature at any part of the diffractometer. The maintenance of high temperatures is controlled by constant gas flow and the temperature is stable within ± 15 K at temperatures between 1800 and 2600 K. The intensity data of an α-Al2O3 single-crystal were successfully collected at 2173 K.

Apparatus for gas flame heating heatresistant materials in fatigue testing

Apparatus for gas flame heating heatresistant materials in fatigue testing

Gas Flame Heating Equipment Providing up to 2300°C for an X-Ray Diffractometer

Gas-flame heating equipment for a single crystal x-ray diffractometer has been designed and constructed for the study of materials in the molten state up to 2300°C. An application of this equipment to structural investigation of molten platinum is discussed. Radial distribution functions were computed and analyzed employing the diffracted intensities.