[en] The use of natural gas to cut metals, in particular steels, is briefly outlined. 9 ills

[en] A new gas burner developed by Radian Corporation and manufactured by Todd Combustion can attain NO_x emission levels of less than 10 ppm. By going back to the fundamentals of the combustion process, it has come up with a burner which gives NO_x levels previously attainable only with selective catalytic reduction. (author)

[en] This study aims to develop a low-temperature catalytic burner using propane and toluene alternately as a fuel and to apply it to the drying of acrylic coatings on textiles. Pt catalysts deposited on ceramic fibres (Al₂O₃) were employed. For propane, the diffusive catalytic burner was used. The combustion efficiency of the diffusive catalytic burner deteriorated rapidly when it was installed in downward position. Two concepts of forced diffusion combustion and premixed combustion were introduced to improve the downward placed diffusive catalytic burner. The combustion efficiency was enhanced with these modifications, but the forced diffusion was preferred since premixed combustion raised the temperature of the catalyst above 700degC leading to sintering of the catalysts. For the toluene catalytic burner the premixed combustion mode was adopted. Its optimum operation conditions were obtained by analysing the temperature within the catalyst layer and by adjustment of the toluene mixture. Field tests were performed on the drying acrylic coatings using the catalytic burners. The results showed that the use of catalytic burners had several benefits such as energy savings and less pollutant emissions. (Author)

[en] All analyses concur in predicting the brilliant future of gas and its high anticipated contribution to the development of the world economy. Demand is expected to increase by over 50% by the year 2010 and to double between now and the year 2030, inter-regional gas exchanges are forecast to triple within 30 years. This article presents the World Gas Congress (WGC-2000) which will take place at Nice (France) in June 2000, the presentation is followed by an overview of some of the newest equipment and services being displayed by French manufacturers and suppliers in the large World Gas Exhibition organized along with WGC-2000 in Nice

[en] Burner configuration in a double burner system effects its performance. Generally, interference between burners degrades their performance and hence increases air pollution from incinerators or industrial burners. However, it has been found that there is a preferred interference that improves the performance of the burners. The selection of a burner configuration that gives the best performance has been found to depend on the equivalent ratio of the feed. A configuration of parallel burners is preferred in a premixed fuel lean case. However a configuration of perpendicular burner is preferred for non premixed diffusion flames. In the premixed fuel lean case, the difference of CO concentration in the fuel gas between the worst and best gas configurations has been found to be 34%. In the premixed fuel rich case, the difference of CO concentration reached 88%. For laminar diffusion flames, where no premixed air is used, the differene has been found to be 167% for CO and 116% for CH4. (author)

[en] The conventional background-oriented schlieren (BOS) technique is an image-based technique that can calculate the density field in fluids using two static images [i.e., an undistorted background image (reference image) and a distorted background image due to the density change in fluids (target image)]. This paper proposes the smartphone BOS (SBOS) technique, which offers the measurement of the density gradient using the high-speed imaging feature of the smartphone being carried with a moving observer. The conventional BOS with a fixed camera visualizes the density gradient by comparing the reference image and the target image. In contrast, SBOS can obtain the time difference of the density gradient field. A reference image in SBOS is a target one at a previous time step. The movement of the smartphone is canceled using a registration technique for image accurate alignment. Three demonstrations are conducted to perform SBOS. First, in a static situation, the density field of heated air by a gas burner is visualized by comparing between SBOS and conventional BOS. Second, the local displacement of density field and the error displacement is estimated quantitatively when the smartphone is moving. Third, SBOS using an embossed wallpaper to visualize the density field is performed in the mobile condition. These achievements suggest that SBOS is an effective system to visualize the density field using only the smartphone, and is expected to be a useful tool such as a preliminary experiment in the laboratory and a teaching tool for general smartphone users.

[en] Mean velocities and turbulence characteristics in the swirling flow of a gun-type gas burner (GTGB) were measured with a triaxial hot-wire probe (T-probe) and compared with previous data measured with an X-type hot-wire probe (Xprobe). Vectors and axial mean velocity data obtained by the measurement of the two types of probes in the horizontal plane and in the cross section differ in magnitude, but have very similar shape in overall distribution. Axial mean velocity components show especially wide differences around the slits and outer part of the swirl vanes within the range of X/R=2. Also, various turbulence intensities appear in a similar trend to axial mean velocity components within the range of X/R=2. The radial component of turbulence intensity around the slits and the outer part of swirl vanes above the range of X/R=2 has an opposite phenomenon. On the whole, the T-probe's measurements appear smaller than the X-probe's. This shows that the X-probe is better than the T-probe, especially on the swirling flow because it is much easier to use

[en] The feasibility of determining the location of a metal target within a gas flame with the aid of a laser rangefinder was theoretically analysed. The effect of the gas flame composition and the combustion regime on the optical parameters of the flame, on the possibility of extracting the signal from the target against the background of the signal reflected from the flame, and also on the accuracy of determination of the target location inside the flame is taken into account.

[en] For many years, due to its intrinsic qualities, flexibility, cleanness, etc., natural gas has been one of the major energy sources used in industry. This paper examines gas appliances of a new conception which use ceramic products in order to reach temperatures of about 1400 degrees C: jet gas burners, counter-rotation burners, integrated preheating burners, high speed burners, double recuperation burners and regenerative ones. Furthermore, the paper deals with these burners applied to industrial furnaces, radiant panels, liquid heating systems and to thermal treatment and crucible furnaces. Particular reference to made to the steam pump, which permits reaching the highest efficiency, and to the gas combustion regulator. With the increased marketing of these new appliances, natural gas ill certainly consolidate its leading position in the industrial and energy fields

[en] Measurements of the content of nitrogen oxides and 16 polyaromatic hydrocarbons (PAH), including napthaline, in flue gas from four natural-gas fired process burners with low emission of nitrogen oxides are presented in addition to measurements of the content of oxygen and carbon dioxide. PAH2 emission was highest at high temperatures and an input effect where the proportion of primary air was low. NO_x emission was dependent on the variation of the proportion of primary air, flue gas temperature and input effect. NO_X emission was highest where the input effect was low, and lowest where the proportion of primary air was low and input effect and flue gas temperature were high. It was possible to adjust the burners so that NO₂ emission was reasonably low without PAH2 emission becoming high. It was concluded that the extent of carbon monoxide emission can be used to indicate that of PAH2. Several gas burners of varying design and combustion principles were evaluated with regard to emission of NO_x and PAH. Fiber burners gave low emission except in the case of PAH2 which was the same as for the other burners. Carbon monoxide emission was higher in the case of duct burners, but in this case it did not mean that PAH2 emission was higher. (AB)