Kuniyuki Kitagawa

Time-Resolved Temperature Profiling of Flames With Highly Preheated/Low Oxygen Concentration Air in an Industrial Size Furnace

A high-speed video camera was combined with a newly developed optical system to measure time resolved two-dimensional (2D) temperature distribution in flames. This diagnostics has been applied to measure the temperature distribution in an industrial size regenerative test furnace facility using highly preheated combustion air and heavy fuel oil. The 2D distributions of continuum emission from soot particles in these flames have been simultaneously measured at two discrete wave bands at 125 frames/sec. This allowed us to determine the temperature from each image on the basis of two-color 2D thermometry, in which the ratio of the 2D emission intensity distribution at various spatial position in the flame was converted into the respective 2D temperature distribution with much higher spatial resolution as compared to that obtainable with thermocouples. This diagnostic method was applied to both premixed and diffusion flames with highly preheated low oxygen concentration combustion air using heavy fuel oil. The results show that higher temperature regions exist continuously in the premixed flame as compared to the diffusion flame. This provided clear indication of higher NO emission from the premixed flame as compared to diffusion flames during the combustion of heavy fuel oil under high-temperature air combustion conditions. This observation is contrary to that obtained with normal temperature combustion air wherein diffusion flames result in highei-HO x emission levels.

Examination of Methane-Hydrogen Mixture Flame Using Isotope Shift/PLIF Spectroscopy

‡We describe and use a new diagnostic method of planar laser-induced fluorescence spectroscopy to observe two types of OH radicals produced from the combustion of hydrogen and methane in a CH4-H2-air premixed flame. Incorporation of planar laserinduced fluorescence spectroscopy is expected to enable one to make two-dimensional (2-D) combustion measurements using an isotopic tracer, which are very difficult in case of using spontaneous emission measurements. We utilize this new diagnostic method to visualize 2-D profiles of OH radical produced from two different sources of CH4-air and H2-air combustion reactions in a CH4-H2-air premixed flame under fuel-lean condition. The results showed high fluorescence intensity of OH radical, concentrated in narrower area around the inner cone of the flame, from H2-air combustion as compared to that obtained from CH4-air combustion. Since OH radical is one of the influential chain carriers in combustion reaction, it is expected that H2-air burning tend to finish more quickly than CH4-air burning in the CH4-H2 fuel mixture flame under oxygen-rich conditions. This is attributed to faster burning velocity and the higher combustibility of H2 as compared to CH4 fuel combustion. These results assist in the co-use of hydrogen with other fuels that may be difficult to burn or pose problems of flammability limits.

Profiling of Redox Atmosphere in Flames by Chemical Seeding/Planar Laser-Induced Fluorescence (CS/PLIF)

Knowledge on the local value of reducing and oxidizing (redox) atmospheres inflames is among the most important issues to be desired by combustion engineers. In this study, the spatial distribution of a redox atmosphere inflames has been measured experimentally by the chemical seeding/laser-induced fluorescence (CS/LIF) technique. A solution of iron was sprayed into a premixed propane-air flame supported on a slot burner. The LIF intensity of FeO band was compared to that of a Fe line to estimate the experimentally determined degree of atomization in the reaction FeO→Fe+O. The flame temperature profile was determined as a rotational temperature and was obtained by comparing the LIF (laser-induced fluorescence) intensities of OH rotational lines. The degree of atomization was theoretically calculated on the basis that simple thermal dissociation takes place in the reaction. The redox atmosphere, or a redox index, is defined as the ratio of the experimentally determined to theoretically calculated degrees of atomization. Two-dimensional distributions or profiles of the excitation temperature, experimentally determined degree of atomization, and redox index have been measured using a charge coupled device (CCD) camera fitted with an optical bandpass filter and the associated signal processing using a computer. This method has been successfully applied to quantitatively illustrate the local atmosphere and profile of the redox atmosphere in flames.

Isotope Shift/Planar Laser Induced Fluorescence Diagnostics for Examining Hydrogen-Methane Flames

The chemical species in a mixture of hydrogen-hydrocarbon flame can be classified into two types according to their origins; one is produced from the hydrogen-air combustion reactions while the other from the hydrocarbon-air combustion reactions. For the separate visualization of the distributions of these two types, we have devised a new diagnostics tool for planar laser-induced fluorescence (PLIF) spectroscopy using isotope shift (herein called IS/PLIF spectroscopy). This diagnostics has been applied for separate visualization of the two-dimensional (2-D) distribution of the fluorescence intensity of the OH radicals produced from the CH4-O2-air combustion reactions and the 2-D distribution from the H2-O2-air combustion reactions in a CH4-H2-O2-air premixed flame. The selectively visualized 2-D distributions of OH radicals showed that the OH radicals produced from the H2-O2-air combustion reactions tend to exist upstream in the flame as compared to the OH radicals produced from the CH4-O2-air combustion reactions. For a quantitative comparison, we calculated the ratio of the 2-D integrated value of the OH fluorescence intensity produced from the CH4-O2-air combustion reactions to the 2-D value of all the OH fluorescence intensity in the CH4-H2-O2-air flame. This ratio is directly proportional to the number of moles of H atoms contained in CH4 in the CH4-H2 mixture.

Environmental Impacts of Hydrogen Production by Hydrothermal Gasification of a Real Biowaste

© 2012 Bircan et al, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Environmental Impacts of Hydrogen Production by Hydrothermal Gasification of a Real Biowaste

Suppression and Monitoring of CO Adsorption onto Pt Catalyst of PEFC

An effect of oxygen supply in to the anode of a polymer electrolyte fuel cell (PEFC) was investigated for suppression of carbon monoxide adsorption onto a platinum catalyst surface . In order to monitor the catalyst reactions, attenuated total reflection infrared (ATR -IR) spectroscopy w as applied. It was revealed from the present study that the oxygen supply is effective for the suppression of the carbon monoxide poisoning onto a platinum catalyst.

New Mass Spectrometric System for Direct Detection of Intermediate Species in Flames

To obtain energy with high efficiency and reduce the toxic emission during combustion, identification of intermediate chemical species in flames is important for better understanding of reaction mechanisms. We have developed a unique system based on ion attachment mass spectrometry (IAMS) for this purpose. In this system, the chemical species generated in flames under atmospheric pressure are introduced directly through a sampling cone of a newly developed interface into the ionization chamber (2Pa). Then the species are ionized by Li + ion attachment and introduced into a quadrupole mass spectrometer operating at 1 x 10 -3 Pa. Intermediate species in flames have successfully been detected. It should be noted that the production of highly toxic environmental pollutants, such as formaldehyde (HCHO) and acetaldehyde (CH3CHO), were confirmed to be produced during combustion of promising alternative fuels, dimethyl ether (CH3OCH3, DME) and ethanol (CH3CH2OH). Additionally, by moving the burner position for detection of the species at various positions, the

Two-dimensional Visualization of Premixed Hydrogen-Oxygen High Temperature Flame

We applied new type high–speed CCD camera to obtain the 2D chemical composition distributions in premixed hydrogen–oxygen flame. This camera can obtain set of four spectrograph images simultaneously by four channels with interference filters. As a measuring object, the combustion flame of the pre–mixed hydrogen–oxygen gas generated by electrolysis was selected. This electrolyzer equipment can generate the high–temperature flame easily, and it has the ability to substitute the conventional acetylene–oxygen frame. As a result, we obtained the distributions of temperature, OH radical and hydrogen beta line i nt heflame. The usefulness of this new type camera was verified.

Two-Dimensional Temperature Distributions of the Surface of Heated Materials by Spectroscopic Measurements

In order to investigate the characteristics of the surface of substrates without destroying and touching them, two-dimensional (2D) surface brightness distributions have been measured with a CCD camera equipped with optical filter (700-800 nm). The images measured with each wavelength gave 2D temperature distributions by two-color thermometry. In addition 2D emissivity distributions were also derived from the derived 2D temperature distribution and the measured images. We demonstrate the convenience and usefulness of this method for heated materials with different surface roughness or with and without coasting of high emissivity material. Subject headings: 2D-temperature distribution, two color method, high temperature, emissivity