Strict relation between the substituents or functional groups attached to the coal macromolecules and the generation of the volatile products, e.g., CH 4 , H 2 O, CO, CO 2 , etc., during the coal pyrolysis is an important but confusing subject. In this paper, quadrupole mass spectrometry, gas chromatography, and 13 C nuclear magnetic resonance are applied to real-time monitoring the formations of volatile products, off-line quantitative determination of the total products from the pyrolysis of a sub-bituminous coal (SC), and the changes of diverse substitents in the SC along with coke foamation, respectively. These measurements are also performed for the pyrolysis of a caking coal to contrast SC. The qualitative and quantitative data reveal that, during coal pyrolysis, the functional groups related with the formation of CO, i.e., ether, carbonyl, and anhydride, can directly generate CO via bond breaking, or take a detour of the formation of other intermediates via condensation and recombination firstly. Moreover, the formations of CO 2 and CH 4 are related to the direct removal of -COO-and -CH 3 , respectively.
Chemical structure of coal is evolutionary changed during pyrolysis that accompanies gas release. The chemical structural change and gas formation profiles play important roles in determining caking property and physical properties such as strength and size of the resultant coke. However, analyses of volatile components and structural analysis of solid char have been mostly performed individually, and it is difficult to combine both and to obtain quantitative understanding on the thermal decomposition of coal at mechanistic level. In this study, simultaneous analyses of solid chemical structures of the heat treated coals and gas formation profiles were conducted for two kinds of coals that were pyrolyzed at an identical condition. On-line gas analysis with a quadrupole mass spectrometer and spectroscopic methods (NMR and FT-IR) were employed for quantitative evaluation of gas formation characteristics and solid chemical structure, respectively. The information obtained were then integrated to acquire new insight for coal pyrolysis mechanism. Here an approach to quantify the transferable hydrogen that contributes to stabilize radicals formed in pyrolyzing coal was proposed. It includes the quantitative assessment of aromatic cluster growth, decomposition of hydroxyls, and releases of hydrogen and pyrolytic water into gas phase. The proposed approach suggested that a bituminous coal that exhibits plasticity during pyrolysis had 3.5 mol/kg-coal transferable hydrogen, whereas the amount of transferable hydrogen of the sub-bituminous coal, a non-caking coal, was 1.3 mol/kg-coal, during pyrolysis up to 500°C.
This study develops a video-rate stereo range finding circuit to obtain the depth to objects in a scene by processing video signals (R, G. B, and brightness signals) from binocular, CCD cameras. The electronic circuit implements a dynamic threshold method to decrease the affection of signal noises in characteristic points detection. where a video signal from each CCD camera is compared with multiple thresholds shifling dynamically by feeding back the previous comparison result. Several object depth measurement experiments for simple indoor scenes show that the dynamic threshold method gives high acquisition and correct rates of depth data compared with those by a fixed threshold method for the video signals and a relative method for R. G, and B signals utilized in the authors' previous range finders.
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