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With the development of modified asphalt waterproofing membrane in China, an exhaust gas purification system was introduced in this paper which had been applied in a waterproofing material company in Hangzhou city of China. In allusion to the shortcomings of current purification methods, a new optimization scheme: high-temperature combustion＋heat recovery＋spray was designed. After optimization, it not only reduced the number of equipment, simplified the management, but also achieved remarkable purification effect. Experimental results showed that the total running costs of the optimized system could be reduced by 837,300 yuan per year, of which the heat recovery system of high-temperature exhaust gas could save natural gas about 95,000 m 3 and costs about 265,050 yuan. [ABSTRACT FROM AUTHOR]

An experimental procedure with post processing to measure the temperature fields in premixed turbulent flame is presented. Temperature measurements were performed on turbulent premixed flame CH4-air with an equivalence ratio ϕ=0.6/1.3. It utilizes the Fine Wire Compensated Thermometry (FWCT) technique. Using fine wire thermocouples for a temporal resolution of the measurement in high temperature requires specific treatment of these values. When the temperature of the environment is high, the radiant loss becomes important. The temperature measured by the hot junction is less than the environment temperature. These losses are estimated by one model, which make it possible to correct the difference between thermocouple temperature and gas temperature. Temperature measure by Fine Wire Compensated Thermocouple requires knowledge of flow velocity, the experimental conditions, the acquisition parameters (sampling frequency) for post-processing. In addition to this, the catalytic effect was incorporated to the final balance equation. The flame temperature and its fluctuations are analyzed by digital processing algorithms. Measurements validation made by the FWCT technique with optical measurement methods (Rayleigh scattering) shows a good agreement. [ABSTRACT FROM AUTHOR]

The growing interest in production of green chemicals and biofuels from biomass provides an incentive for pulp mills to identify new possibilities in recovering more wood components from the pulping process. One possibility is to use lignin, separated from black liquor. We undertook this work to determine the combustion properties of reduced-lignin black liquors--two kraft liquors and one soda liquor--in a laboratory-scale, singleparticle furnace. The combustion times, maximum swollen volume, nitric oxide formation, cyanate formation, and sulfur release were measured for the original liquors, the filtrates, and intermediate levels of lignin reduction. Combustion experiments were conducted at 900°C in 10% oxygen. Cyanate formation experiments were carried out by pyrolyzing the droplets at 800°C in 100% nitrogen to form a char. The chars were then gasified at 800°C in a 13% carbon dioxide/87% nitrogen atmosphere to obtain the smelt. Sulfur release was studied by pyrolyzing the samples at temperatures ranging from 300°C to 900°C. Liquors with the lowest lignin content had a smaller maximum swollen volume than the original sample. The devolatilization time was not affected by the lignin removal to any great extent, but lignin removal did have a clear effect on the char burning time. The amount of formed nitric oxide (g N/kg black liquor solids) remained constant or decreased slightly with increasing lignin removal in the kraft liquor samples, while for the soda samples the amount of nitric oxide formed increased. The amount of cyanate decreased clearly when comparing the samples with lowest lignin content to the original liquor samples. The peak sulfur release occurred at 500°C for both kraft liquors. In almost all experiments, the share of sulfur released was highest for the original samples and lowest for the sample with lowest lignin content. These results provide new data on combustion properties for reduced-lignin black liquors and indicate that for lignin removal levels up to about 20%, no significant changes are expected in the combustion behavior. [ABSTRACT FROM AUTHOR]

Abstract: The implosion technique has been used to extend measurements of turbulent burning velocities over greater ranges of fuels and pressures. Measurements have been made up to 3.5MPa and at strain rate Markstein numbers as low as −23. The implosion technique, with spark ignition at two opposite wall positions within a fan-stirred spherical bomb is capable of measuring turbulent burning velocities, at higher pressures than is possible with central ignition. Pressure records and schlieren high speed photography define the rate of burning and the smoothed area of the flame front. The first aim of the study was to extend the previous measurements with ethanol and propane–air, with further measurements over wider ranges of fuels and equivalence ratios with mixtures of hydrogen, methane, 10% hydrogen–90% methane, toluene, and i-octane, with air. The second aim was to study further the low turbulence regime in which turbulent burning co-exists with laminar flame instabilities. Correlations are presented of turbulent burning velocity normalised by the effective rms turbulent velocity acting on the flame front, , with the Karlovitz stretch factor, K, for different strain rate Markstein numbers, a decrease in which increases . Experimental correlations are presented for the present measurements, combined with previous ones. Different burning regimes are also identified, extending from that of mixed turbulence/laminar instability at low values of K to that at high values of K, in which is gradually reduced due to increasing localised flame extinctions. [Copyright &y& Elsevier]

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Abstract: Shock tube measurements of ignition delay times with high activation energies are strongly sensitive to variations in reflected shock temperatures. At longer shock tube test times, as are needed at low reaction temperatures, small gradual increases in pressure (and simultaneous increases in temperature) that result from incident shock wave attenuation and boundary layer growth can significantly shorten measured ignition delay times. To obviate this pressure increase, we made use of a recently developed driver-insert method of Hong et al. that allows generation of near-constant-volume test conditions for reflected shock measurements. Using this method, we have measured propane ignition delay times in a lean mixture (0.8% C3H8/8% O2/Ar) over temperatures between 980 and 1400K and nominal pressures of 6, 24 and 60atm, under both conventional shock tube operation (with post-shock fractional pressure variation dP 5/dt ∼1–7%/ms) and near-constant-volume operation (with dP 5/dt ∼0%/ms). The near-constant-volume ignition delay times provide a database for low-temperature propane model development that is independent of non-ideal fluid flow and heat transfer effects. Comparisons of these near-constant-volume measurements with predictions using the JetSurF v1.0 mechanism of Sirjean et al. and the Curran et al. mechanism of NUI Galway were performed. Ignition delay times measured with dP 5/dt ∼1–7%/ms were found to be significantly shorter (about 1/3 of the near-constant-volume values) at the lowest temperatures and highest pressures studied. However, these ignition times are successfully simulated using the JetSurF v1.0 mechanism when an appropriate gasdynamic model that accounts for changes in pressure and temperature is used. [ABSTRACT FROM AUTHOR]

Abstract: A systematic exploitation of state variable correlations for increasing the accuracy and significance of laser-based measurements in combustion is proposed, formally developed and applied to an example. Correlations between state variables (species concentrations and temperature) lead to the phenomenon that the realizable states in a combustion system are on or close to low-dimensional manifolds in state space, allowing an approximate description of the system state in terms of a few variables. This makes it feasible to approximately determine the full state of a combustion system by means of just a few simultaneous laser-based measurements. As an example application of the method, a simple system with a low-dimensional manifold is constructed by steady and unsteady flamelets. The fuel and oxidizer correspond to a series of well-documented, turbulent, non-premixed methane/air jet flames (Sandia Flames A–F). This low-dimensional manifold is then used to determine state variables via polarized/depolarized Rayleigh-signals. The results show that even in very complex, turbulent flames, many quantities can be determined by means of just two signals. Some quantities are more prone to errors than others. The errors originate in the sensitivities of species with respect to signal noise and with respect to deviations of the actual states from the assumed, steady/unsteady-flamelet-based low-dimensional manifold. [Copyright &y& Elsevier]

Liquefied petroleum gas (LPG) is a popular fuel for domestic and commercial cooking as it offers clean cooking environment as well as high heat content. Large increases in the demand of LPG in developing countries like India, in the face of its dwindling reserve, underscores the need for performance improvement of LPG cook stoves. The present paper investigates the combustion and emission characteristics of the LPG cook stove burners commonly used in India, and have suggested performance improvement through different designs modifications in the burner cap and fuel injection nozzle. It is found that the increase in the diameter of the ports admitting the fuel–primary air mixture and obliquely orienting the ports to impart swirl to the flow enhances the performance through better efficiency and reduced emissions and soot formation. The smaller orifice hole in the fuel injection nozzle also improves the performance through increased efficiency and reduced emission at the expense of decreasing burner loading. The design improvements are easy and economic to implement, and can lead to nearly 3% of improvement in system thermal efficiency and significant reduction in emission. [ABSTRACT FROM AUTHOR]

Abstract: Simultaneous CH and OH planar laser-induced fluorescence (PLIF) and stereoscopic particle image velocimetry (PIV) measurement have been developed to investigate the local flame structure of turbulent premixed flames. In this system, high-speed CMOS cameras were adopted to capture clear stereoscopic particle images without contamination by the flame radiation. The effects of scattering of CH PLIF laser by tracer particles are carefully investigated to improve signal-to-noise ratio in CH fluorescence images. The developed simultaneous two radical concentrations and three-component velocity measurement on a two-dimensional plane was applied to relatively high Reynolds number turbulent premixed flames in a swirl-stabilized combustor. All measurements were conducted for methane–air premixed flames in the corrugated flamelet regime. Simultaneous CH and OH images suggest the presence of the isolated burned gas in the unburned mixture and the isolated unburned mixture in the burned side, which have been predicted by direct numerical simulations. Detailed analysis of simultaneous CH and OH images reveals that the minimum curvature radius of the flame front coincides with the Kolmogorov scale. Strong three-dimensional velocity fluctuations, which are measured by the stereoscopic PIV, imply that misunderstanding of the flame/turbulence interactions would be caused by the analysis of two-component velocity distributions in a cross-section. Furthermore, comparisons of CH–OH PLIF and three-component velocity fields show that the burned gases do not always have high-speed velocity in a relatively high Reynolds number turbulent premixed flame. The Reynolds number dependence of the flame front was clearly captured by the simultaneous CH–OH PLIF and stereoscopic PIV measurements. [Copyright &y& Elsevier]

Abstract: Chemiluminescence sensing is shown to be a useful approach for monitoring local, reaction zone equivalence ratios. For natural gas combustion, the ratio of CH? to OH? chemiluminescence is shown to be a useful indicator of equivalence ratio (?). The ratio of peak intensities (CH?/OH?) is shown to monotonically increase with ? for the operating regime studied (0.6< ? <1.2). A “universal” relationship between CH?/OH? and ? was demonstrated, for the first time, in various natural gas combustor configurations ranging from unconfined jet flames to swirl- and dump-stabilized combustors. This relationship was also not sensitive to moderate changes in flowrate (velocity), air preheating, and fuel composition (methane vs. natural gas). The universal dependence of CH?/OH? on ? is obtained by correcting the peak chemiluminescence intensities for broadband background radiation associated with other gases (e.g., ) and hot surfaces. Pressure does impact CH?/OH?; the results indicate an increase in the ratio with pressure (for fixed ?). There may be a nonmonotonic behavior below 3bar for near stoichiometric (? >0.8) mixtures. In addition, the sensitivity of CH?/OH? to changes in ? decreases with pressure. A swirl-stabilized, liquid-fueled (n-heptane) combustor was also investigated. Volume-integrated measurements in this nonpremixed combustor show that is a more sensitive measure of ? for complex fuels, compared to CH?/OH?, with measurable signals even in lean mixtures (unlike the natural gas results). In addition, the chemiluminescence sensing technique successfully tracts the variation of fuel–air ratio with axial location in this nonpremixed combustor. [Copyright &y& Elsevier]

Abstract: Intracavity laser absorption spectroscopy (ICLAS) was used to measure concentration profiles of NH2 in low pressure (30Torr) methane/oxygen/nitrogen flames doped with small amounts of N2O, NO, and NH3. The effective optical length of ICLAS, which dictates the sensitivity of the method, is controlled by the generation time of the quasi-cw-laser. The effective optical length of 0.87km, reached at generation time of 75μs, provides very high sensitivity: from 5×1010 molecules/cm3 at 500K in the vicinity of burner up to 2×1011 molecules/cm3 in the burned gas zone (T ∼1800K). The radial profile of NH2, measured using a tomographic technique, indicates that the radical is located mainly inside a cylinder with diameter equal to the burner diameter. For the first time, the absolute mole fraction profiles of NH2 were measured in hydrocarbon flames with different dopants and compared with one-dimensional calculations based on the GRI-3.0 mechanism. The dependence of the NH2 concentrations on the equivalence ratio is in excellent agreement with the model prediction. The absolute NH2 concentration values for different dopants are predicted very well by the calculations apart from the NO-doped flame where GRI-Mech 3.0 overpredicts the NH2 concentration by a factor of 2. In the ammonia-doped flame, the calculations predict an additional concentration maximum located close to the burner. This maximum is not observable in the experiment. All the experimental profiles exhibit 1–2mm shift further from the burner surface in comparison with the predicted ones. The reasons of those discrepancies are discussed. [Copyright &y& Elsevier]

Abstract: An extrapolation technique that provides semi-quantitative estimates for the infrared absorption coefficients of gaseous fuels at temperatures beyond those for which measurements are generally practical (>700K) is presented. The new method is based on a simplified expression for molecular line intensities consisting of three fitting parameters and two variables (temperature and frequency). The accuracy of the extrapolations was tested first by comparing predictions of absorption coefficients for CO, CO2, and H2O vapor to the corresponding values obtained directly from the HITEMP molecular database. Finally, to establish the practical utility of the method, the spectrum of propane at 1000K obtained from the extrapolation technique was compared to actual experimental measurements. [Copyright &y& Elsevier]

The characteristics of natural-gas direct-injection combustion under various fuel injection timings were studied by using a rapid compression machine. Results show that natural-gas direct injection can result in combustion that is much faster than homogeneous combustion while shortening the time interval between injection timing and ignition timing can markedly decrease the combustion duration. Unburned hydrocarbon would increase over a wide range of equivalence ratios, shortening the time interval between injection timing and ignition timing can decrease the value to that of homogeneous-mixture combustion. The NO[sub x] level is high but the CO level is low over a wide range of equivalence ratios and is little affected by fuel injection timing. High values of pressure rise due to combustion can be realized and it is insensitive to the variation in fuel injection timing. High combustion efficiency can be achieved, which is also independent of injection timing. [ABSTRACT FROM AUTHOR]

Improving estimates of carbon inventories in soils is currently hindered by lack of a rapid analysis method for total soil carbon. A rapid, accurate, and precise method that could be used in the field would be a significant benefit to researchers investigating carbon cycling in soils and dynamics of soil carbon in global change processes. We tested a new analysis method for predicting total soil carbon using laser‐induced breakdown spectroscopy (LIBS). We determined appropriate spectral signatures and calibrated the method using measurements from dry combustion of a Mollisol from a cultivated plot. From this calibration curve we predicted carbon concentrations in additional samples from the same soil and from an Alfisol collected in a semiarid woodland and compared these predictions with additional dry combustion measurements. Our initial tests suggest that the LIBS method rapidly and efficiently measures soil carbon with excellent detection limits (∼300 mg/kg), precision (4–5%), and accuracy (3–14%). Initial testing shows that LIBS measurements and dry combustion analyses are highly correlated (adjusted r2 = 0.96) for soils of distinct morphology, and that a sample can be analyzed by LIBS in less than one minute. The LIBS method is readily adaptable to a field‐portable instrument, and this attribute—in combination with rapid and accurate sample analysis—suggests that this new method offers promise for improving measurement of total soil carbon. Additional testing of LIBS is required to understand the effects of soil properties such as texture, moisture content, and mineralogical composition (i.e., silicon content) on LIBS measurements. [ABSTRACT FROM AUTHOR]

Alalyses the results when ammonia and ethene are mixed in the combustion chamber of a circulating fluidised-bed boiler. Details on the procedure; Comparison of the concentration profiles for ammonia; Conclusion reached.

Describes the results of an experimental study undertaken in an industrial regenerative flow-type oil-fired furnace for the production of glass containers. Industrial glass-melting furnace and instrumentation; Carbon monoxide and nitrous oxide exhaust levels; In-flame temperature profiles; Importance of the results on the development of 3-D mathematical models.

The article presents an historical note concerning the title of the novel "Fahrenheit 451," by Ray Bradbury, a Talmudic tale of a Rabbi being immolated, and the actual combustion temperature of paper. The Jewish legend is retold, describing the slow burning of the letters of the Torah during the incident and commenting on the physical explanation of the phenomena. Details are also given describing the rationale behind the title of "Fahrenheit 451," citing Bradbury's mistake in using the Fahrenheit scale instead of Celsius.