Combustion Apparatus Research Articles

The Wickbold combustion method for the determination of mercury under statistical aspects

The combination of the Wickbold combustion apparatus with a mercury/hydride atomic absorption spectrometer for the routine determination of mercury is investigated. A flow injection system is used to introduce the solution from the decomposition into the spectrometer. The data obtained are treated by several statistical tests which have been recommended for quality control purposes. Simplicity of the statistical treatment is emphasized. The mercury content of certified reference materials is determined using the Wickbold combustion unit, and the resulting data are analyzed statistically.

The determination of tritium, 14C and 35S in milk and crop samples using a combustion technique

The use of a combustion technique for the determination of low energy beta-emitting radionuclides in solid and liquid samples has been in widespread use for a number of years. However, the sensitivity of measurements by existing commercially available combustion apparatus has been limited by the amount of sample that can be combusted before incorporating the combustion products into a liquid scintillator for subsequent counting. Consequently the determination of tritium, 14C and 35S at environmental levels has not been possible using commercially available equipment. This paper describes the apparatus and method that was developed at the Central Veterinary Laboratory for the determinatination of these low energy beta-emitters in milk and crop samples. A typical sample size of 20–50 g is routinely measured, although the apparatus is designed to be able to make sveral sequential combustions before measurement of the oxidation products by liquid scintillation counting.

Study of the thermal degradation of some varnishing systems applied in the automobile industry

The results of investigations on the thermal stability of selected automobile finishing lacquers are reported. Thermal analysis (TA) and pyrolysis techniques were used to study the degradation behaviour and to determine the residual quantity of ash. The samples were decomposed in air and additionally pyrolyzed in nitrogen at a temperature of 450°C and different residence times by the use of modified Bayer-ICI-Shell combustion apparatus (BIS). Qualitative and quantitative investigations of the decomposition or pyrolysis products were performed by gas chromatography-mass spectrometry (GC/MS).

5160069 Integrated power unit combustion apparatus and method: Reinhard M Klaass, Bert Minshall, Francis J Suriano, William Caan assigned to Allied-Signal Inc

5160069 Integrated power unit combustion apparatus and method: Reinhard M Klaass, Bert Minshall, Francis J Suriano, William Caan assigned to Allied-Signal Inc

Evaluation of the coke formation potential of residual fuel oils

Previously, engineering control and prediction of coke particulate emission has been hampered by the apparent inadequacy of the existing heavy fuel tests that were used as coking indicators, specifically: asphaltene contents (heptane and pentane), viscosity, specific gravity, and the Ramsbottom and Conradson Carbon Residues. A new measurement, the Coke Formation Index (CFI) has been established as a more accurate measure of the coke particulate formation propensity of residual oils. This parameter, combined with previously reported results concerning particle diameter dependence on initial droplet conditions, will allow more accurate prediction of heavy oil combustion particulate emissions than was previously possible. This improved understanding of the factors affecting cenospheric coke formation and oxidation will increase the potential for control of coke particulate emission. The CFI is measured using a free, isolated droplet combustion apparatus, closely simulating the conditions experienced by droplets in a real boiler and yet separating the coke formation and oxidation processes. The CFI has been evaluated for 41 different residual fuels. From these experiments the Coke Formation Index (CFI), or ratio of the particulate mass to the initial droplet mass, has been established as principally related to fuel properties. Correlation exists between the CFI and the fuel asphaltene content or the Ramsbottom or Conradson Carbon Residues, however there is also considerable variation. Close similarity to the carbon formation results reported by others using electrically heated foils is observed; however, the CFI technique also provides particle size, morphology and composition information not generated by other coke formation tests. Results suggest that, from a single experiment with only a small mass of fuel, the resultant particle size and mass distribution can be predicted for the spray distribution of full scale burners firing the same fuel.

Experimental investigation of free droplet combustion under microgravity

A new apparatus for free droplet combustion under microgravity was developed. The principle of the new apparatus is as follows: A fuel droplet is suspended at the overlapping ends of two opposed filaments. Under a microgravity condition, the filaments are rapidly pulled away from each other at the same time and speed to release the droplet immediately after ignition. For realizing the above process, a pin-jointed rhombic frame is employed, which is mounted around the combustion chamber. The feasibility and reliability of experiments with the apparatus are much higher than those of the previous one. By using the new apparatus, experiments were conducted to obtain the characteristics of droplet combustion with special reference to the middle and later periods of burning, and n-heptane and ethyl alcohol were examined as a sooting and a non-sooting fuel, respectively. The results obtained are as follows: The flame/droplet diameter ratio increases at the early period of burning for both fuels and then, at the later period, the ratio increases for n-heptane and decreases for ethyl alcohol, respectively. The assumption of quasisteady burning of droplets cannot be verified. Extinction can be observed for both fuels, and burn-out, only for n-heptane.

平成元年における重要な燃料関係事項 ８． 燃焼機器・熱機関

平成元年における重要な燃料関係事項 ８． 燃焼機器・熱機関

Investigations into the thermal decomposition of the pesticides metoxuron and chloridazon

The herbicides Metoxuron and Chloridazon were thermally decomposed in a VCI combustion apparatus developed by the ‘Verband der Chemischen Industrie’ at temperatures of 400, 600, 800 and 1000°C. Most of the decomposition products were identified and quantitatively determined by means of gas chromatography with flame ionization detection and combined gas chromatography/mass spectrometry. The compositions of the volatile degradation products of the two herbicides are quite similar. Aromatic compounds such as benzene, phenylisocyanate, benzonitrile, naphthalene, naphthonitrile and phenanthrene were formed during the combustion process. For Metoxuron additional compounds such as chlorobenzene, chlorophenylisocyanate, derivatives of chlorophenol and phenol, biphenyl, acenaphthylene, isoquinolineamine, propylisocyanate and 5-aminopyrozalidone were identified.

Investigations into the thermal decomposition of selected pesticides

Selected pesticides (Metolachlor and Captafol) were decomposed in a so-called VCI combustion apparatus which has been developed by the ‘Verband der Chemischen Industrie’. Most of the decomposition products could be identified by means of gas chromatography/ mass spectrometry. A quantitative gas chromatographic analysis was carried out for several pyrolyzates. For Metolachlor the aromatic compounds benzene, toluene, styrene, naphthalene and nitrogen-containing compounds like benzonitrile and indole derivatives were detected, among others. The thermal decomposition of Captafol yielded benzene, trichloroethylene, benzonitrile and phthalimide as the main products.

Thermal formation of polybrominated dibenzofurans from decabromodiphenyl ether in a polybutylene-terephthalate polymer matrix

Pure decabromodiphenyl ether (PBDPO) and several commercial polybutyleneterephthalate polymer samples containing PBDPO and antimony(III) oxide have been pyrolysed at temperatures ranging from 300°C to 800°C. The experiments were carried out in a vertical combustion apparatus with a constant air flow-rate of 165 ml/min, and the combustion products have been analysed for polybrominated dibenzofurans (PBDF). The polymer samples showed maximum formation of PBDF at 400–600°C in yields to 16%. At 300°C PBDF formation is very low, and at 800°C debromination is almost complete. With pure PBDPO the yields in the same combustion apparatus are much lower and the temperature maximum is higher (700°C).

Aerodynamic device for generating mono-disperse fuel droplets

A device has been developed for generating well-defined, one-dimensional streams of small (200–1000 μm), mono-sized droplets of a variety of fuels. The droplets produced are well separated (>30 droplet diameters), making this technique well suited to experimental combustion studies of unsupported, isolated droplets. This method has been used successfully to generate droplets of light and mid-distillate petroleum fuels, heavy oils, boron/JP-10 slurries, and coke/oil slurries, for a range of combustion studies. The principle of operation of the device is the aerodynamic stripping of incompletely formed droplets emerging from the tip of a capillary/fine wire which resides in the throat of a venturi or convergent nozzle. By varying the fuel flow rate through the capillary, the gas flow rate through the nozzle, and the diameter of the capillary, precise control of the initial droplet size, spacing, frequency, and velocity can be achieved. Design criteria, exemplary results, and a brief survey of other droplet generating schemes are presented, along with a description of the integration of this device into a laboratory combustion apparatus.

Thermal decomposition of decabromodiphenyl ether

Decabromodiphenyl ether has been decomposed by use of a vertical combustion apparatus, applying different air flow-rates and temperatures of 400, 600, 800 and 1000° C. The main decomposition products have been identified as brominated aliphatic and aromatic compounds such as tetrabromoethene, hexabromobutadiene, pentabromobenzene, hexabromobenzene, octabromostyrene, hexabromofuran, hexabromoindone, heptabromodibenzodioxin, heptabromodibenzofuran, octabromodibenzodioxin, and octabromodibenzofuran.

Extinction and structure of methane/very lean methane-air counterflow diffusion flames

Experimental studies of extinction and structure of methane/very lean methane-air counterflow diffusion flames were made using a porous cylinder burner. The extinction limit of diffusion flame, the onset of luminous carbon zone, thermal and chemical structure of the flame, and the limiting concentration of methane diluted with nitrogen, below which a laminar diffusion flame can never be established in the very lean methane-air mixture, were examined. The experimental results show that the critical stagnation velocity gradient for flame extinction and the critical stagnation velocity gradient for the onset of the luminous carbon zone increase almost linearly with the increase of the equivalence ratioof the very lean mixture, although the rate of increase of the latter is not so large as compared with the former. The increase of the flame strength is attributed to the extension of the high temperature region and the increase of the flame temperature. The limiting methane concentration decreases almost linearly with the increase ofin the range up to the lean flammability limit of the mixture. The results suggest that, when the diffusion flames are used in combustion apparatus, it is very attractive to use the very lean mixture as the oxidizer.

環境試料中の｀１２７´Ｉおよび｀１２９´Ｉの中性子放射化分析法

The analytical method of 127I and 129I in environmental samples has been studied and the background levels of these nuclides in soils, seaweeds and milk were measured.The analytical method consists of the combustion technique and neutron activation analysis (N. A. A.).The iodine was separated from samples by ignition at about 1, 000°C in a quartz combustion apparatus with an oxygen and a nitrogen stream, and was absorbed by small amounts of active charcoal. The iodine was then purified through the carbontetrachloride extraction method and the PdI2 decomposition method. Irradiation was conducted by JRR-4 (nth: 8×1013n/cm2·sec) for 40min. After irradiation, the iodine was purified by the solvent extraction method same as pre-irradiation extraction. Each activity of 126I and 130I, which was produced by 127I (n, 2n) 126I and 129I (n, γ) 130I reaction respectively, was measured by γ-spectrometry using a Ge-detector.The lower detection limits of 129I by this method were 4×10-7Bq/g for dry soil, 7×10-8Bq/g for fresh seaweeds and 7×10-6Bq/l for fresh milk, respectively. The relative standard deviation of 129I measurements in soil and milk were less than 10%.

Determination of rates of product consumption and soot formation during combustion of solvents commonly carried by rail

A two-phase study of the combustion of solvents carried in large quantity by rail was performed. The first phase involved development of protocol and apparatus for determining the amounts of soot produced and heats of combustion for several commonly carried commodities under varying conditions of oxygen availability. In the second phase, the rate of product consumption, hereafter referred to as the “burnrate“, was measured for solvents under controlled conditions. This paper presents a description of the combustion apparatus, the protocols used and the burnrate data obtained. The possibility of developing a predictive model for burnrate or amount of soot generated based on physical and chemical properties of the solvent is explored.

Combustion of poly(1-methyl hexamethylene) and poly(1-methyl tetramethylene) and identification of the main decomposition products

The Bayer-ICI-Shell apparatus has been used to carry out combustion experiments on poly(1-methyl hexamethylene) (PH) and poly(1-methyl tetramethylene) (PT) using different air flow rates at various combustion temperatures. The products were adsorbed on charcoal followed by benzyl-alcohol desorption. They were separated and identified using gas chromatography. The non-oxidized products were identified as short chain, saturated and unsaturated hydrocarbons while the main oxidized products are short chain ketones and alcohols. The intensities of the chromatographic peaks of the separated products depend upon the temperatures and air flow rates in the combustion apparatus.

An Inexpensive Combustion Apparatus for Preparation of Radioactive Samples

The combustion apparatus described provides a rapid and inexpensive alternative for measurement of radioisotopes in plant parts. The apparatus utilized a nickel-chromium resistance wire connected to a low-voltage transformer to generate the heat required to ignite the plant tissue. The nickel-chromium wire also served as the sample holder. Combustion was performed in an O2-flushed liquid scintillation vial, and the combustion gases containing either 14CO2 or 3H2O were trapped in situ, scintillant was added, and the vials assayed for radioactivity. The percentage of the radioactivity recovered after combustion was 96.0 for 14C and 93.4 for 3H with standard deviations of 6.8 and 3.0%, respectively.

Determination of traces of sulfur in selenium by molecular emission cavity analysis

The selenium sample (ca. 1 mg) containing 40–90 μg g -1 sulfur is decomposed in a combustion apparatus and the evolved sulfur dioxide is adsorbed on about 30 mg of silica gel. The silica gel is deposited in a cavity and the sulfur is determined by molecular emission cavity analysis. Incomplete sulfur recoveries (86 ± 4%) caused by incomplete conversion to sulfur dioxide necessitate a correction factor.

Automation of an In-Situ Combustion Tube and Study of the Effect of Clay on the In-Situ Combustion Process

Abstract A fully automated in-situ combustion apparatus supported by a minicomputer was designed, constructed, and tested. Results obtained from four adiabatic dry combustion runs to investigate the effect of clay on crude oil combustion are reported. Sand mixtures of varying clay (kaolinite) content were saturated with crude oil and water. The fourth run was performed with amorphous silica powder in the sand mixture for comparison with clay results. We concluded that the large surface area of the clays was a major contributor to the fuel deposition process. However, different oxygen utilization efficiencies obtained from both types of sand mixtures indicated that mechanisms controlling the combustion reaction also depended on the composition of the porous matrix. A thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC) were used to obtain kinetic data on the effects of kaolinite type clay on crude oil combustion. The addition of kaolinite clay or silica powder changed the shape of the crude oil TGA/DSC thermograms significantly, but sand had no effect. The major effect on DSC thermograms was a shifting of the large amount of heat produced from a higher to lower temperature range. Reduction of activation energy caused by the addition of kaolinite clay to the crude oil indicates both catalytic and surface area effects on combustion/cracking reactions.

The decomposition of oils and fats in a stream of oxygen for the determination of trace elements

For the determination of Al, Cr, Mn, Fe, Cu, Zn, Se, Cd, Hg and Pb at μg g -1 and ng g -1 levels in oils and fats by electrothermal atomic absorption spectrometry (a.a.s.), the sample is burnt in a stream of pure oxygen in a special combustion apparatus (Trace-O-Mat). Volatile elements are condensed on a cold finger cooled with liquid nitrogen. After combustion the trace elements are dissolved off the cooled areas and from the sample holder by refluxing with 2 ml of high-purity nitric acid (65%). Recoveries were tested on reference materials by electrothermal a.a.s. and were found to be ⩾ 95%.