Furnace Combustion Methods

The Dohrmann DX 20B system is based on combustion of a sample to produce a hydrogen halide, which is then swept into a microcoulometric cell and estimated. It is applicable at total halide concentrations up to 1000 pg/1 with a precision of 2% at the 10 pg/1 level. The detection limit is about 0.5 pg/1. Analysis can be performed in five minutes. A sample boat is available for carrying out analysis of solid samples. 

Mitsubishi also supplies an automatic total halogen analyser (model TOX-10) which is very similar in operating principles to the Dohrmann system discussed previously, i.e., combustion at 800-900 °C, followed by coulometric estimation of the hydrogen halide produced. 

Manatt [5] determined chlorine in polystyrene (PS) by C nuclear magnetic resonance spectroscopy. 

The Mitsubishi trace sulfur analyser models TS-02 and TN-02(S) again involve a microcombustion procedure in which sulfur is oxidised to sulfur dioxide, which is then titrated coulometrically with triiodide ions generated from iodide ions  

The Mitsubishi TSX-10 halogen-sulfur analyser expands the technology of the TOX-10 to include total chlorine and total sulfur measurement. The model TSX-10, which consists of the TOX-10 analyser module and a sulfur detection cell, measures total sulfur and total chlorine in liquid and solid samples over a sensitivity range of milligrams per litre to a percentage. Dohrmann also produces automated sulfur and chlorine analyser (models MCTS 130/120). This instrument is based on combustion microcoulometric technology. 

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ASTM D-5016. Standard Test Method for Sulfur in Ash from Coal, Coke, and Residues from Coal Combustion Using High-Temperature Tube Furnace Combustion Method with Infrared Absorption. 

ASTM D-4239. Standard Test Methods for Sulfur in the Analysis Sample of Coal and Coke Using High Temperature Tube Furnace Combustion Methods. 

Infrared absorption is one of three standard test methods for sulfur in the analysis sample of coal and coke using high-temperature tube furnace combustion methods (ASTM D-4239). Determination of sulfur is, by definition, part of the ultimate analysis of coal (Chapter 4), but sulfur analysis by the infrared method is also used to serve a number of interests evaluation of coal preparation, evaluation of potential sulfur emissions from coal combustion or conversion processes, and evaluation of the coal quality in relation to contract specifications, as well as other scientific purposes. Infrared analysis provides a reliable, rapid method for determining the concentration of sulfur in coal and is especially applicable when results must be obtained rapidly for the successful completion of industrial, beneficiation, trade, or other evaluations. 

Other procedures include high-temperature tube furnace combustion methods for rapid determination of sulfur in coal and coke, using automated equipment. The instrumental analysis provides a reliable and rapid method for determining sulfur contents of coal or coke. By this method, total sulfur as sulfur dioxide is determined on a continuous basis. 

Filter-pump, 44 Filtration through cloth, 131 under reduced pressure, 43 with fluted filter, 53 "Fischer s ester method, 133 Fluorescein, 187 Fluted filter, 53 Formic acid, 106 Fractional distillation, 136 Fractionating columns, 137 Freezing-point method, 32 I -riedel-Crafis reaction, 210 furnace, combustion, 4 tube, 23 ... 

At the USDA Forest Service, Forest Products Laboratory (FPL), Brenden and Chamberlain (6) examined the feasibility of measuring heat release rate from an ASTM E-119 furnace. Three methods of measuring heat release were considered the substitution method, oxygen consumption method, and weight of material/heat of combustion method. The oxygen consumption method was shown to be the most advantageous way to measure heat release. However, data were limited to a few assemblies. Chamberlain... 

Elemental composition H 1.56%, Te 98.44%. The gas is identified by its physical properties and measured by chemical analysis. Two most confirmatory methods recommended here are (1) GC/MS, the characteristic mass ions should be in the range 126 to 132, and (2) furnace-AA or ICP emission spectroscopic analysis for metalic tellurium. For the AA analysis, hydrogen telluride gas should be passed through water and the solution acidified and analyzed for tellurim. Hydrogen may be measured by the classical combustion method involving oxidation to form water, followed by gravimetry. 

The Determination of Selenium. The most difficult trace element to determine in coal by wet chemical methods is selenium. Two alternative dissolution techniques can be used—H. L. Rooks combustion method (7) and the oxygen bomb combustion method (4). Also, two alternative analytical methods can be used—the hydride evolution method (5) and the graphite furnace method. 

Kotz etal. (1972, Decomposition of biological materials for the determination of extremely low contents of trace elements in limited amounts with nitric acid under pressure in a Teflon tube) Hartstein et al. (1973, Novel wet-digestion procedure for trace-metal analysis of coal by atomic absorption) Jackson etal. (1978), Automated digestion and extraction apparatus for use in the determination of trace metals in foodstuffs) Campos etal. (1990, Combustion and volatilization of solid samples for direct atomic absorption spectrometry using silica or nickel tube furnace atomizers) Erber et al. (1994, The Wickbold combustion method for the determination of mercury under statistical aspects) and Woit-tiez and Sloof (1994, Sampling and sample preparation). 

The principles for flue gas cleaning will be similar to those for pulverized coal combustor boilers, except that in addition to the use of a selective catalytic reduction (SCR) system for NOx reduction, various other combustion methods can be used, such as two-stage combustion, and a rebum concept in which 15%-35% of the coal is pulverized, and added into the main boiler chamber, bypassing the cyclone furnace. 

For the low-temperature synthesis of LaA103, Taspinar and Tas (1997) proposed a self-propagating combustion synthesis from aqueous solution containing urea and the respective nitrate salts. A pure perovskite phase was obtained at 1023 K, which is one of the lowest temperatures reported for the powder s)mthesis of LaA103 so far. Han et al. (2006) used a combustion method for the s)mthesis of Eu " -activated YAIO3 and GdA103 by redox reactions between the respective metal nitrates and glycine in a preheated furnace at 773 K. 

Analysis of Metals (1) proposes the combustion method combined with iodo-metric titration for the determination of sulphur concentrations above 50 Mg/g. The sample weight is 1 g. The combustion is carried out in a tube furnace at 1250 to 1300°C, using oxygen. The combustion gases are absorbed in 100 ml hydrochloric acid (3+200). The titration is performed using a potassium iodate-iodide solution (0.2225 g KIO /l) and starch as indicator, whereby in the course of the combustion so much iodate solution has to be continuously added that the light blue colour of the solution does not vanish. When the combustion is running lower it has to be titrated slowly. 

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