Total Sulphur In Coal Research Articles

Optimization of coal desulfurization method by sub/supercritical fluid extraction with binary mixtures of carbon dioxide and ethyl lactate as a solvent

Coal combustion for energy results in the emission of air pollutants such as NOx and SOx, which negatively affect human health and the environment. Reducing toxic gas emissions and ash production is needed to achieve cleaner coal. This study aimed to develop an extraction method for desulfurizing coal with non-toxic solvents before combustion. Mixtures of sub/supercritical carbon dioxide and ethyl lactate (EL) were used at temperatures of 60–80 °C and extraction times of 15–45 min. Box-Behnken design (BBD) was used to assess the influence of the extraction parameters and to optimize the extraction method. The results show that higher temperatures and lower EL content significantly increased desulfurization. The optimal conditions for desulfurization were CO2/EL (95:5, v/v) at 80 °C, 300 bar and 15 min, reducing total sulfur in coal from 1.90 to 0.13% by weight. The extraction was efficient for removing organic sulfur, sulfones and sulfates, whereas there were still traces of sulfoxides and sulfides remaining in the coal after extraction. Moreover, the ash content slightly decreased while the calorific value increased by 8% and 3% by weight, respectively. The use of a temperature less than 100 °C and an extraction time of 15 min make this method "greener" in comparison to other proposed "green" methods, which use temperatures above 200 °C. Thus, the method has the potential to produce clean coal.

Method of Identifying Total Sulfur Content in Coal: Geochemical and Geophysical Logging Data from the Upper Paleozoic in North China.

The research of sulfur content and logging parameters in coal seams is of great significance for accurate mining and efficient utilization of coal. Taking 81 coal samples collected from the Upper Paleozoic in North China as an example, coulometric titration and chemical reagent methods were used to determine the contents of total sulfur and morphological sulfur in coal seams, and correlation analysis and multivariate linear fitting methods were used to analyze the relationship between total sulfur in coal and the shape and peak value of logging curve. The results show that the content of total sulfur in the Upper Paleozoic coal seams ranges from 0.19% to 12.36%. The morphological sulfur in coal is mostly pyrite sulfur, followed by organic sulfur and sulfate sulfur. The logging curves of the deep lateral resistivity log (LLD), natural gamma ray (GR), short-distance gamma gamma (CGS), and spontaneous potential (SP) in coal seams from Shanxi Formation are funnel-shaped, tooth-shaped, box-shaped, and flat-shaped, respectively. The shapes of LLD corresponding to a few coal seams with a sulfur content of less than 3.0% are finger-shaped and bell-shaped, and GR is finger-shaped. The GR, CGS, acoustic (AC), and density (DEN) curves corresponding to Taiyuan Formation coal seams with a total sulfur content more than 3.0% (St,d ≥ 3.0%) are mainly box-shaped, and the LLD curve corresponding to high-sulfur coal seams is mostly tooth-shaped. The LLD, GR, CGS, and AC curves are second only to funnel-shaped, and the DEN curve is tooth-shaped. The LLD, GR, AC, CGS, and DEN curves of coal seams with a total sulfur content less than 3.0% are mainly box-shaped. GR, AC, and DEN curves are next to tooth-shaped, LLD is bell-shaped, and CGS curve is finger-shaped. The total sulfur content in coal has a negative correlation with LLD and CGS values and a positive correlation with GR, AC, DEN,and SP values. The prediction model of total sulfur in coal is established by using a multivariate linear fitting method through geophysical logging parameter values, which can provide a method for comprehensively quantifying the change of total sulfur content in coal seams.

Determination of total sulfur in coal by ultraviolet fluorescence method based on the large capacity combustion framework

In this paper, a systematic method for determination of total sulfur in coal by ultraviolet fluorescence is established based on a self-developed large capacity combustion framework (LCCF). The simple oxidation-combustion mode is upgraded to the pyrolysis-oxidation-combustion mode with the help of LCCF. Thus, components to be analyzed is pyrolyzed slowly and the whole decomposition process of sample is prolonged, which could improve the consistence of test results. The sampling size to be sent into LCCF is significantly increased, and the representativeness of samples is secured, which promotes the improvement of accuracy of testing results. Detection limits are augmented without additional hardware or software improvements by this way. The test systems equipped with conventional combustion tube (CCT) and self-developed LCCF are established differently to test standard coal samples (SCS) and ordinary coal samples (OCS) with different total sulfur range. Accuracy and precision of the two test systems are tested and the optimal injection quantity of the system with LCCF is determined. The results show that LCCF could support the injection quantity of 1000mg and ensure stable and complete combustion of sample, which is far more than that of CCT. The accuracy and precision of the test results are better than the requirements of the existing conventional analysis standards, which shows the excellent structure of LCCF and good performance. The new analysis system can further expand the application of ultraviolet fluorescence method in field of coal and others.

Waterberg coal characteristics and SO2 minimum emissions standards in South African power plants

Key characteristics of coal samples from the supply stock to the newly commissioned South African National Power Utility's (Eskom's) Medupi Power Station – which receives its supply coal from the Waterberg coalfield in Lephalale (Limpopo Province, South Africa) – were evaluated. Conventional coal characterisation such as proximate and ultimate analysis as well as determination of sulphur forms in coal samples were carried out following the ASTM and ISO standards. Coal was classified as medium sulphur coal when the sulphur content was detected in the range 1.15–1.49 wt.% with pyritic sulphur (≥0.51 wt.%) and organic sulphur (≥0.49 wt.%) accounted for the bulk of the total sulphur in coal. Maceral analyses of coal showed that vitrinite was the dominant maceral (up to 51.8 vol.%), whereas inertinite, liptinite, reactive semifusinite and visible minerals occurred in proportions of 22.6 vol.%, 2.9 vol.%, 5.3 vol.% and 17.5 vol.%, respectively. Theoretical calculations were developed and used to predict the resultant SO2 emissions from the combustion of the Waterberg coal in a typical power plant. The sulphur content requirements to comply with the minimum emissions standards of 3500 mg/Nm3 and 500 mg/Nm3 were found to be ≤1.37 wt.% and ≤0.20 wt.%, respectively.

99/02913 Improvement of determination of total sulfur in coal by Eschka gravimetric method

99/02913 Improvement of determination of total sulfur in coal by Eschka gravimetric method

98/03507 Rapid reliable determination of ash and total sulfur in coal

98/03507 Rapid reliable determination of ash and total sulfur in coal

Coal oxidation and calcium loading on oxidized coal

Abstract A Pittsburgh No. 8 coal, and two IBC (Illinois Basin Coal) 101 and 112 coals were oxidized in a 2 1 Parr Stirred Bench Top Reactor. The oxidation time was varied up to 5 h; the temperature from 150°C to 225°C, the oxygen pressure from 100 to 600 psi, and coal dosage from 15 to 60 g in 600 ml of distilled water. The oxidation of coal was evaluated by measuring total acidic group formed on the coal surface as well as by measuring adsorption of calcium ion on the oxidized coal from a solution in a separate system. It was found that upon oxidation of coal, acidic groups were formed on the coal surface and were responsible for the adsorption of calcium ion. The oxidation increased with increasing oxygen pressure without much leveling-off effect. However, the oxidation increased sharply with increase in temperature from 150°C to 180°C and then tended to level off above 180°C. The optimum oxidation conditions were determined by considering BTU loss and Ca/S molar ratio where S is the total sulfur in coal. The optimum oxidation conditions of Pittsburgh No. 8 coal were 170°C and 500 psi O 2 with 60 g of coal for 3 h, while those of IBC 112 coal were 150°C and 500 psi O 2 with 60 g of coal for 3 h. Under these conditions, the Ca/S molar ratio reached approximately 1.3 and the BTU loss was less than 20%. This value of Ca/S molar ratio may be high enough to capture sulfur during fluidized combustion and coal gasification. Thus, it is concluded that the present method has the potential to be used in a commercial process for preparation of a feed stock for fluidized-bed combustion and coal gasification.

蛍光Ｘ線法による石炭中硫黄の分析 Ｉ 全硫黄

Correction for absorption is necessary for inorganic elements when X-ray fluorescence is applied to the determination of total sulfur in coal slab sample . The merit is that inorganic elements can also be determined at the same time . The correction procedure of X-ray fluorescence method developed by Berman and Ergun is simplified by calculation of absorption coefficients using temporary concentrations of sulfur and inorganic elements obtained from intensities and calibration lines, and the accuracy of the present X-ray results is discussed by comparing with the results by combustion-IR method . The coal in medium rank is used to prepare standard samples for calibration lines. The inorganic elements, Sr, Fe, Ti, Ca, K, Cl, P, Si, Al and Mg, are taken up for the absorption coefficient correction . Circular slab sample is made by pressing finely powdered sample of coal in aluminium ring.Experiments were carried out with 26 coal samples of various ranks from lignite to low volatile bituminous by this proposed method and the combustion-IR method . The results of the analyses of total sulfur show that this method is useful to determine the total sulfur in coal and that the increase of the main inorganic element number adopted for absorption coefficient correction improves the precision to some extent. The limit of ash content for this method is found to be about 50%.

Determination of total sulphur in coal by x-ray fluorescence spectrometry

A precise x-ray fluorescence method for the determination of sulphur in coat. The sample is mixed with calcium oxide and active carbon and is gradually heated to 900°C. After coding, lithium tetraborate and lead oxide are added and a prepared. The Pb M α line is used as an internal standard for the K K α line. The results for coal have a relative standard deviation of approximately 1% and exhibit.

Sulphate capture in ash and boiler deposits in relation to SO 2 emission

The paper reviews the chemical reactions and physical changes of mineral impurities in pulverized coal-fired flames which result in the formation, deposition and retention of sulphates in boiler deposits and in the ash captured in the electrical precipitators. The review is based mainly on the author's own work and it includes the results of laboratory research and boiler plant investigations. British coals when consumed in pulverized fuel-fired boilers result in a retention of sulphates in the ash and boiler deposits which accounts for between 12 and 18% of the total sulphur in coal. The residual alkalinity of pulverized fuel ash derived from bituminous coals is equivalent to a further 4–6% of SO 2 in the flue gas.

Rapid and simple determination by combustion of total sulphur in coal

A simple and rapid procedure for determining total sulphur in coal is described. A stoichiometric recovery from a wide variety of coal types containing 0.1–8 wt% sulphur is obtained by ignition at 1160–1180 °C in the commonly available resistance-type tube furnaces such as those used for carbon determinations. The procedure is accurate and uses readily available materials. It is particularly rapid as it consists of only two steps: sample weighing and mixing with a solid oxidant and combustion in a furnace for 7.5–9 min in an alternating nitrogen-oxygen stream with an accompanying titration. The sample and oxidant (vanadium pentoxide and chromic oxide) are heated to ≈1170 °C, any sulphur trioxide produced is reduced to sulphur dioxide by copper heated to near its melting point and chlorine is removed by a hot aluminium gauze plug. To ensure complete recovery of sulphur, oxygen is introduced in brief cycles into the nitrogen carrier flow system. The resulting sulphur dioxide is absorbed in perchloric acid solution and titrated with potassium iodate.

The determination of total sulphur in coal by a semi-micro tube-combustion method

The determination of total sulphur in coal by a semi-micro tube-combustion method

A pH finish to the oxygen-flask method for analysing total sulphur in coal

A pH finish to the oxygen-flask method for analysing total sulphur in coal

燃焼法による燃料中の全硫黄の定量について（主として石炭，コークス及び重油中の全硫黄の定量について）

燃焼法による燃料中の全硫黄の定量について（主として石炭，コークス及び重油中の全硫黄の定量について）