Sulfur In Coal Research Articles

Sulfur Conversion of Mixed Coal and Gangue during Combustion in a CFB Boiler

The construction of a power plant using a 660 MWe supercritical circulating fluidized bed (CFB) boiler with co-combustion of coal and gangue has been proposed in China. Therefore, this study simulated the distribution law and transformation mechanism of sulfur-containing phases using three low-calorific samples of gangue and coal mixtures under different conditions, based on the thermodynamic simulation software HSC Chemistry. The results showed that sulfur low in calorific value coal is mainly converted into gas phase SO2, solid phase alkali metal sulfate (Na2SO4 and K2SO4), and alkaline earth metal sulfate (CaSO4 and MgSO4) in an oxidizing atmosphere. Under a reductive atmosphere, sulfur in coal is mainly converted into gaseous H2S, COS (Carbon oxysulfide), and solid FeSx. With an increase in the O/C ratio, the distribution curve of sulfur-containing substances contracted to lower temperatures. It was established that the sulfur fixation capacity of coal ash depends on the relative amounts of basic oxides and sulfur present in it. Relevant conclusions were also verified and compared to those of the laboratory small-fluidized bed test bench and the 3 MWth CFB combustion test bench.

РОЗПОДІЛ РТУТІ У ВУГІЛЬНОМУ ПЛАСТІ C7Н ПОЛЯ ШАХТИ «ПАВЛОГРАДСЬКА»

Purpose. Investigation of regularities of mercury distribution in coal of formation c7n of the Pavlogradska mine field. Methodology. Method of atomic absorption analysis of furrow samples of wells. Processing of geochemical and structural-geological data by methods of mathematical statistics using Excel 2016 and Statistica 6.0. The computer program Surfer was used to build maps/ Results. In article considered the distribution of mercury in the coal seam c7н of the Pavlohradska mine field of the Pavlohrad-Petropavlivka geological and industrial district of Donbas. As a result of the study, a map of isoconcentrates and a map of the regional component of mercury content in the coal of the seam were constructed and analyzed. Correlation coefficients between mercury concentration and formation morphological parameters and coal sulfur were calculated. The regression equations between this element and the ash content of coal are also established, which will allow predicting their concentration in the main working coal seams of the geological-industrial area relative to the values of coal ash content. The nature of sulfur distribution is established and the weighted average concentrations and the main descriptive statistics of this element are calculated. Scientific novelty. Peculiarities and regularities of mercury accumulation in coal of formation c7n are revealed. Practical significance. The constructed maps and established correlations are the factual basis for long-term forecasting of mercury concentrations in extracted raw materials and adjustment of technological schemes of coal beneficiation. Keywords: mercury, mine, coal height, ash content, stratum depth, sulfur content, regression equation, correlation coefficient.

Appraisal of SOx Emission from Flue Gas in Thermal Power Station and Dry Sorbent Injection (DSI) Method to Reduce SOx

Electrical vitality created in any nation is one of the advancement estimates happens in that nation. The vitality delivered is principally founded on the accessible assets, for example, streaming water, coal, oil, gas, atomic fills, wind, sunlight based and so forth. The accessibility of wealth coal in India had incited the influence plant organizers to introduce coal based warm influence stations. During the pre-autonomy and post-freedom period in mid fifties, the need was to produce control and consequently much consideration was not paid to the contamination perspective and this proceeded up to late seventies. Most of intensity plants in India extending from not many MW to 500 MW or more are of pummeled fuel terminated boilers using low calorific, low coal sulfur, high debris content sub-bituminous coal. Because of consuming of the coal, discharges, for example, Particulate Matter (PM), Oxides of Sulfur (SOx) and Oxides of Nitrogen (NOx) aside from CO2, CO are diverted to the climate through the vent gas. The mindfulness made by contamination impact on the general public and the tremendous measure of disintegration exposed to the gear constrained the specialists to make contamination standards increasingly stringent. In this paper, the methodology to reduce SOx from flue gas in an old lower capacity power station is discussed and the optimum and cost effective methodology adopted is Dry Sorbent Injection (DSI) by injecting sodium bicarbonate or sodium carbonate or trona in the flue gas path after furnace and before/after Air-preheater to remove SO2/SO3 from the flue gas. The removed sulphate will be collected along with ash in ESP or Fabric Filter in a Bag house

Development of Flue Gas Desulphurization Reactor for Reducing SOX Emission from Flue Gases Emitted in Thermal Power Plants

Electrical energy produced in any country is one of the development measures takes place in that country. The energy produced is mainly based on the available resources such as flowing water, coal, oil, gas, nuclear fuels, wind, solar etc. The accessibility of bounty coal in India had provoked the power plant organizers to introduce coal based warm power stations. During the pre-autonomy and post-freedom period in mid fifties, the need was to create control and subsequently much consideration was not paid to the contamination angle and this proceeded up to late seventies. The awareness made by contamination impact on the general public and the colossal measure of disintegration exposed to the gear constrained the specialists to make contamination standards increasingly stringent. These convincing standards which appeared in eighties required the power plant faculty to change the contamination control gear in the current power plants introduced during early days. Most of intensity plants in India going from not many MW to 500 MW or more are of pounded fuel terminated boilers using low calorific, low coal sulfur, high debris content sub-bituminous coal. Due to burning of the coal, emissions such as Particulate Matter (PM), Oxides of Sulphur (SOx) and Oxides of Nitrogen (NOx) apart from CO2, CO are carried away to the atmosphere through the flue gas. In this paper, the methodology to reduce SOx from flue gas in a coastal power station in is discussed and the optimum methodology adopted is Seawater Flue Gas Desulphurisation (SWFGD) using the alkalinity of the seawater to scrub SO2 from the flue gas. The seawater used in the FGD system is from the once through Condenser outlet of the Turbine system and since there is no by-product to be disposed, the seawater FGD is the optimum SOx reducing mechanism for a coastal thermal power station.

Total Sulfur and Ash Yield of Tanjung Formation Coal in Sekako, Barito Basin, Central Kalimantan: Implication of Depositional Process

Tanjung Formation is one of the major coal-bearing deposit in the Barito Basin, Central Kalimantan. The distribution of total sulfur and ash yield in coal is closely related to the depositional environment. This study was to determine the total sulfur and ash yield and the interpretation of the dynamics of depositional process. Coal seam A and B generally have low to medium ash yield 2.82 to 9.23 (wt.%, db) and low total sulfur content of <1 (wt.%, db), except for the 6PLY1 coal sample which has total sulfur content that relatively high at 1.55 (wt.%, db). Coal samples 5PLY1A, 5PLY1B, 5PLY3, 5PLY5, 6PLY2, 6PLY4, 6PLY5, 6PLY7, and 6PLY9 which have low to medium ash yield and low total sulfur content <1% (wt.%, db) are formed in the topogeneous mire (freshwater swamp) in a fluvial environment. The total sulfur content was interpreted to be derived mainly from the parent plant materials. Meanwhile, the 6PLY1 coal sample which has an ash yield of 5.83 (wt.%, db) and total sulfur content of 1.55 (wt.%, db) formed in topogeneous mire in an environment that is invaded by sea water, and the total sulfur content were interpreted coming from the parent plant materials and the effect of seawater invasion which is rich in sulfate (SO4) compounds. It is also supported by the occurrence of syngenetic mineral content (framboidal pyrite) and epigenetic pyrite of 1.23 (vol.%).

Distribution of Sulfur during Solvent Extraction of Coals and Desulfurization of Extracted Product

Three kinds of coal with different ranks and sulfur contents were extracted using 1-methyl naphthalene at 350°C. The sample coals were fractionated into three fractions: a solvent-soluble fraction, a deposited fraction from the solvent-soluble fraction at room temperature, and the solvent-insoluble fraction. The forms of sulfur in the raw coals and the extracted products were determined by X-ray adsorption near edge structure analysis. Most of the inorganic sulfur was transferred to the solvent-insoluble fraction and the organic sulfur was distributed among the three fractions. Interestingly, the solvent-soluble fraction contained organic sulfur without inorganic sulfur, and only thiophenic sulfur was detected independent of coal type. Because of the high selectivity of imidazolium type ionic liquid for thiophenic sulfur, dimethyl imidazolium methyl sulfate was applied to extract the sulfur contained in the solvent-soluble fraction. The extractive experiment using ionic liquid showed that the sulfur content decreased linearly with the number of extraction stages. A high extent of desulfurization was obtained with a high concentration of ionic liquid.

Transformation characteristics of sodium, chlorine and sulfur of Zhundong coal during O2/CO2 combustion in circulating fluidized bed

Transformation characteristics of sodium, sulfur and chlorine during the high-sodium Zhundong coal combustion were investigated by performing both air combustion and O2/CO2 combustion experiments in a 50 kW circulating fluidized bed testing system. Via analyzing the chemical compositions and crystalline phases of ash samples, the following results were obtained. In comparison with air combustion, sodium release into gas phase was inhibited under O2/CO2 combustion atmosphere at the identical oxygen concentrations. While increasing the inlet oxygen concentration under O2/CO2 combustion could promote the release of sodium. Chlorine almost finished total release from the coal under all experimental conditions. Besides, sulfation reaction affected the transformation of sodium, sulfur and chlorine markedly, for it could alter the chemical form of sodium from chloride to sulfate and further influence the release and condensation process of sodium during the combustion process. In particular, elevating the inlet oxygen concentration could promote the sulfation reaction and reduce the content of chlorine in deposits significantly.

Study on the modification of high energy electron beam irradiation of high sulfur coking coal

ABSTRACT This study was designed to illustrate how high-energy electron beam (HEEB) irradiation can be used to treat Gao Yang coking coal (GY) and Shui Yu fat coal (SY). The effects of different irradiation (5 kGy, 10 kGy, and 20 kGy) on coal quality characteristics and physical and chemical structure were also studied. The structure of the coal samples was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Industrial analysis results showed that irradiation of samples reduced the amount of moisture and ash. The dehydration rate of SY coal when using an irradiation of 20 kGy reached a maximum of 48.11%. XPS results showed that irradiation treatment could not directly remove organic sulfur, but it possibly transforms the thiophene sulfur (low valence state) in coal to sulfones (high valence state). The FTIR spectra showed that the side chain of fats and the C = C of aromatic hydrocarbons in the coal were destroyed during radiation. XRD spectra showed the inorganic mineral composition on the surface of coal samples changed. In addition, irradiation effectively improves the pore capacity and pore channel structure of coal samples, resulting in an apparent increase in the specific surface area.

Investigation on the synergistic mechanism of coal desulfurization by ultrasonic with microwave

ABSTRACT This investigation reports the exploration on synergistic action of ultrasound and microwave treatments during coal desulfurization. The sulfur content, surface property, and sulfur form variations of Xinyu coal samples were determined after treating by different methods with peroxyacetic acid, including ultrasonic (US), microwave (MV), MV followed by US (MV-US), and US followed by MV (US-MV). Experimental results showed that in the order of US-MV > MV-US > MV > US had positive effects on coal desulfurization. It was found that the surface characteristics of coal samples were improved due to the physical effects of the US, which was conducive to the further oxidation of sulfur-containing groups in the following MV treatment. The organic sulfur in coal could be oxidized deeply using the combined treatment of US and MV. These findings confirmed that the synergy of US and MV treatments could serve as a reference for further optimizing the coal desulfurization process.

Changes in sulfur functionality during solvent extraction of coal in HyperCoal production

In this paper, the structural changes of the chemical forms of sulfur in coal, as induced by thermal extraction with industrial solvents (HyperCoal [HPC] production), were examined using X-ray photoelectron spectroscopy (XPS). In raw coal, thiophenic sulfur is more common than alkyl sulfides, and the observed structural changes during solvent extraction depend on the initial chemical form of sulfur. The majority of sulfur remains in the residue after extraction, and inorganic sulfur is found only in the residue. Only thiophenic sulfur (~84%) and sulfoxides (~16%) were found in the resulting HPC; no other types of sulfur (e.g., alkyl sulfides) were detected. These results demonstrate that, during HPC extraction, sulfates are not extracted and that some or most of the extracted alkyl sulfides, sulfoxides, and sulfones are likely decomposed and eliminated as gases. It was found that thiophenic and sulfate sulfur are unaffected by the extraction process and are found in the HPC and/or the extraction residue.

Screening of bacteria for coal beneficiation

Biobeneficiation is considered to be a clean coal technology as an alternative method to reduce sulfur and ash content present in coal by using microbes, in particular bacteria. Recent studies have demonstrated that bacteria can oxidize iron and reduced sulfur compounds present in coal because they promote the oxidative conversion of the reduced forms of sulfur to soluble, easily washed-out compounds. Moreover, the use of bacteria in coal beneficiation has the following advantages, such as simple operation, extensive installation, performed under the mild condition without harmful product, low energy consumption and eco-friendly method. Hence, this study dealt with the investigation of the bacteria capable of oxidizing iron and sulfur compounds and also reducing ash content present in coal. Nine bacteria isolated from mercury-contaminated gold mine sites in Bandung, West Java Province, Indonesia were screened for their ability to oxidize iron and sulfur compounds and reduce ash content. Of the nine bacteria studied, two bacteria (i.e., Pseudomonas plecoglossicida and Pseudomonas hibiscicola) were able to oxidize iron and sulfur compounds and reduce ash content at pH of ~4. The findings of this study provide evidence that both bacteria could be employed as an oxidizing agent that will be applicable for the beneficiation of coal.

Experimental study on ash deposition of Zhundong coal in oxy-fuel combustion

To facilitate the large-scale utilization of high-alkali and -alkaline earth metals (AAEMs) coals in power generation, the ash deposition behaviors of a typical Zhundong coal in oxy-fuel combustion were experimentally investigated using a drop tube furnace. A wall-temperature-controlled ash deposition probe by which the bulk gas temperature could be measured simultaneously was designed and employed in the experiments. The deposition tendencies, ash morphologies, chemical compositions of deposited ash particles were studied respectively under various oxygen concentrations, bulk gas temperatures, probe surface temperatures and probe exposure times. The experimental results revealed that the oxygen concentration had a significant influence on the deposition behavior during oxy-fuel combustion of high-alkali coal. Compared with air case, more fine ash particles were generated during the combustion of Zhundong coal in 21% O2/79% CO2 atmosphere but the deposition tendency was weaker. However, a higher oxygen concentration could aggravate the tendency of ash deposition. The high contents of iron (Fe), calcium (Ca), sulfur (S), and sodium (Na) in Zhundong coal could result in the generations of low-melting point compounds. Calcium in flue gas existed as CaO and was captured prior to SO3 by the probe surface during the ash deposition process. At the initial 30 min of the ash deposition process, the dark spherical fine ash particles rich in Fe, Na, oxygen (O), and S were largely produced, while in the range of 60–90 min the light spherical fine ash particles with high contents of Ca, barium (Ba), O, and S were generated on the other hand. The deposition mechanisms at different stages were different and the melted CaO (BaO)/CaSO4 (BaSO4) would give rise to a fast growth rate of ash deposit.

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

An open air stockpile of conical shape was formed with 3.5 m base diameter and 5 m height using 500 tons of − 200 mm size ROM thermal coal on a concrete floor. Coal sample from the stockpile were collected at 30 days interval for analysis of various chemical properties like; proximate analysis, ultimate analysis, gross calorific value (GCV) and various combustion related properties such as ignition temperature, peak temperature, burnout temperature, maximum combustion rate, ignition index, burnout index, combustion performance index and combustion rate intensity index. Experimental results show that, due to weathering of coal fixed carbon decreased from 35.6% to 19.9%, elemental carbon (C) decreased from 46.6% to 28.6%, hydrogen (H) decreased from 3.3% to 2.9% and GCV decreased by up to 55% of original value during 330 days of storage of coal in an open atmosphere. Ash content of coal increased form 29.2% to 46.6% due to loss of combustibles. Sulfur (S) of coal was found to get increased from 0.33% to 1.08% during storage. The activation energy of coal combustion increased from 22 kJ/mol to 54 kJ/mol. Variation in combustion parameters signifies that weathering has significant negative impact on coal combustion properties as coal become difficult to ignite.

Lignite oxidative desulphurization: notice 3\u2014process technological aspects and application of products

The study reviews the process of oxidative desulphurization of high-sulphur Ukrainian lignite, which was performed by coal treatment using an air or air–steam mixture. In the process, sulphur-free fuel and tar from the decomposition of coal organic matter was obtained. Hence, the sulphur in the coal was converted into hydrogen sulphide. The coal desulphurization process is critical to power generation, power generation and technology, and technology field of application. The coal desulphurization process ensures the maximum recovery of the highest content of sulphur and hydrogen sulphide (H2S) in desulphurized gases at minimal energy costs. The process also enhances the maximum decomposition of tar and sulphur recovery (> 50%) during coal power generation. Based on summarized field studies, a block schematic diagram coupled with heat and material balances of the process was developed for the calculations. The application of the technology at the first stage of coal combustion in thermal power plants will enable the utilization of over 50% of recovered coal sulphur in the form of concentrated H2S or commercial elemental sulphur. This will, nevertheless, allow for a reduction of sulphur oxide pollution in the environment by at least 53%–56%. It has been suggested that the product of thermal decomposition of coal organic matter (tar) can be used as a component of furnace fuel oil or as a plasticizer of petroleum-based road bitumen.

Mechanism of coal electrochemistry desulfurization under alkaline conditions

To study the desulfurization mechanism of coal-derived pyrite and organic sulfur in coal, the experiment used the solution of NaOH whose concentration is 2.0mol/L as electrolyte to dispose high sulfur coal samples whose content is 3.08% with the H type undivided electrolytic cell, and analyzed the before and after desulfurization of coal samples by scanning electron microscope, XRF and IR spectrum and the filtrate is from after electrolyzing coal sample by ion chromatograph. The results showed that the inorganic sulfur of coal sample mainly in the form of Pyrite that is a fine granular distribution in the coal and disseminates on the coal particle, then pyrite is removed by generating sulfate at the anode oxidation reaction, and finally, organic sulfur in coal samples mainly is removed by electrochemical reaction that can convert into the form of sulfate radicals.

Desulfurization of low rank coal co-pyrolysis with reduced iron powder followed by dry magnetic separation

Organic sulfur in coal is usually integrated with macromolecular skeleton structure of organic components and hence difficult to remove through physical separation. Chemical leaching and biological treatments are considered as the effective methods for the removal of organic sulfur from coal, however these treatment processes require huge investment and long treatment period. In this paper, low rank coal co-pyrolysis with reduced iron powder (Fe powder) and then followed by dry magnetic separation was used to reduce the sulfur content of low rank coal. After dry magnetic separation, the organic sulfur content can be reduced from 2.00% for low rank coal before the pyrolysis to 0.33% for the coal after 700 °C co-pyrolysis with Fe powder at the coal/Fe-powder mass ratio of 4:1. However, the organic sulfur content can be only reduced to 1.28% for the coal after 700 °C pyrolysis without Fe powder. The Fe powder can promote/enhance the decomposition of organic sulfur and the released sulfur can be bonded with Fe powder to form the sulfocompounds which is separated along with the Fe powder during dry magnetic separation. X-ray photoelectron spectroscopy was used to indicate the sulfur forms in the separated Fe powder (namely magnetic tailings) and showed the magnetic tailings contained more FeS and FeS2 compounds than the Fe powder before the pyrolysis. The magnetic tailings contained about 4.6% sulfur content at the co-pyrolysis temperature of 700 °C while the sulfur content of the Fe powder before the pyrolysis was nearly zero. A large proportion of organic sulfur was transferred to the Fe powder and then was separated along with the magnetic tailings by dry magnetic separation.

Feasibility study of reduction removal of thiophene sulfur in coal

The present work investigated an effective reductive desulfurization method for thiophene sulfur in high organic sulfur coal utilizing the potassium tert-butoxide/hydrosilane. Maximum decreases of 65.8% and 64.2% in organic sulfur for Xinyu coal and Guxian raw coals were, respectively obtained under the optimized conditions of the molar ratio of reductive assistant to sulfur of coal (15), treatment time (80 min), temperature (215 °C). According to the results of XPS, more than 80% mercaptan, sulfoether and thiophene on the raw coals surface were removed without destroying the macromolecular structure of coal. Sulfur on treated coal surface samples mainly existed in the form of sulfonate and sulfone due to the hydrolysis and oxidation of intermediate products generated in the reduction desulfurization reaction. These findings confirmed the possibility of effective removal for thiophene sulfur in coal utilizing the reductive system, which could give a reference for thiophene sulfur removal of high organic sulfur coal.

A deep insight into arsenic adsorption over γ-Al2O3 in the presence of SO2/NO

Arsenic is easily evaporated during coal combustion, which not only raises serious environmental concerns but also results in the deactivation of catalyst in selective catalytic reduction (SCR) systems. It is a promising method to use sorbents for the capture of arsenic vapors (As2O3(g)) before As-containing flue gas entering SCR catalyst. However, arsenic has a strong affinity with sulfur in coal and SO2 in the coal combustion flue gas strongly suppresses As2O3(g) capture by typical Ca/Fe-based sorbents. This study estimated the selective capture of As2O3(g) by γ-Al2O3 and the effects of SO2 and NO on the arsenic adsorption were investigated. The results showed that As2O3(g) adsorption over γ-Al2O3 was effectively conducted at temperatures ranging from 300 to 400 °C. In the reacted γ-Al2O3, arsenic was predominantly in the form of As3+ through reactions with Al-O bonds and positive charged alumina ions. SO2 was slightly adsorbed on γ-Al2O3, which had a limited effect on arsenic adsorption. The adsorption of SO2 on γ-Al2O3 mainly occurred on the sites of hydroxyl groups (Al-OH) and few adsorbed SO2 was bound with positive charged alumina ions. NO was catalytically oxidized by γ-Al2O3 and released as NO2. Nevertheless, NO competed with As2O3(g) to adhere to positive charged alumina ions and strongly suppressed arsenic adsorption over γ-Al2O3. Fortunately, in the presence of SO2, NO was mostly transformed into intermediate (-SO3NO) at the sites of Al-OH on γ-Al2O3. As a result, the adverse effect of NO on the adsorption of As2O3(g) was weakened.

Biodesulfurization of high sulfur fat coal with indigenous and exotic microorganisms

Abstract Coal is the most abundant fossil fuel in the world and its combustion accompanies with the emission of SOX, which is responsible for serious environmental problems. To reduce the emission of SOX is essential for clean fuel. In the present study, indigenous microorganisms acclimatized from fat coal itself and exotic microorganisms from sewage sludge were used for coal biodesulfurization. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectral analysis were used to investigate the structural change of fat coal during the bioleaching. Results showed that kaolinite and quartz were the main minerals, and pyrite was the main inorganic sulfide in fat coal. After 36-day biodesulfurization, the total sulfur in fat coal decreased from 5.07% to 2.77% and 2.75%, and the pyritic removal was 77.68% and 87.88% with indigenous and exotic microorganisms, respectively. The exotic microorganisms were more effective to oxidize the pyrite than the indigenous microorganisms. But both microorganisms did not interact with the organic sulfur, which existed as C S bond in fat coal. FT-IR analyses showed the damage of kaolinite structure, indicating potential microbial effect on kaolinite, which has not been reported before. Raman spectral analysis was for the first time used to investigate the changes of coal macromolecular structure during the bioleaching. FT-IR and Raman spectra confirmed the changes of aromatic C H, O H bonds, which led to the increase of carbon crystallinity index.

A comparative study on characteristics of sulfur and nitrogen transformation and gaseous emission for combustion of bituminous coal and char

The characteristics of sulfur and nitrogen transformation and the emissions’ comparison of sulfurous and nitrogenous gas were investigated using SEM, XPS, TG-FTIR and TG-gas analyzer during the combustion process of Shenmu bituminous coal (SM coal) and its char. SEM indicated that porosity and specific surface area of char were enlarged after coal pyrolysis and a large amount of space could be provided for the oxidation reaction of various sulfur species with oxide during the combustion process. The sulfur and nitrogen species of the two samples analyzed by XPS showed that, pyritic sulfur, organic sulfide sulfur, sulfone and sulfoxide sulfur in coal were partly transformed to thiophenic sulfur and sulfate sulfur in the pyrolysis of coal, and the total sulfur content in char was reduced. Besides, the sulfur and nitrogen species’ changes in SM coal, char and the ashes determined by XPS showed that sulfur fixation effect was enhanced in the presence of calcium oxide during combustion. The component analysis of the gas during combustion via TG-FTIR indicated that SO2 and NO2 began to escape at 300 °C and reached maximum at about 1100 °C, by contrast, the emissions of SO2 and NO2 of char were below that of SM coal throughout the whole combustion process. The wide range of TG-gas analyzer analysis revealed that the SO2 and NOx emissions of SM coal were 2.51 and 1.71 times as much as char burning, respectively.