Petrographic and geochemical investigation of coal slurries and of the products resulting from their combustion

Jelonek, Iwona; Mirkowski, Zbigniew

doi:10.1016/j.coal.2015.02.005

Cited by 10 publications

(8 citation statements)

References 34 publications

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“…Physical properties of these slurries depend on factors such as size and distribution of the particles, concentration of solids, agitation of the mixture, temperature, and viscosity of the carrier. Water is the most used fluid, but several mineral and vegetable oils, or even biodiesel or alcohol, can also be used [10].…”

Section: Coal-water Slurriesmentioning

confidence: 99%

Potential of Coal–Water Slurries as an Alternative Fuel Source during the Transition Period for the Decarbonization of Energy Production: A Review

Nunes

2020

Applied Sciences

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Coal–water slurry or coal–water mixture (CWS or CWM) is a complex solid–liquid dispersion. Several research works have been done concerning the production and use of CWSs being developed worldwide in several different governmental, industrial and academic facilities. In the present paper, studies on the developments achieved in the past three decades with regard to the field mentioned above are systematically reviewed, with particular regard to several different aspects during the combustion process. The structure and properties of the coal are highlighted, as are the different additives used and their adaptability with different types of coal, where the particle size distributions are of great importance in determining both the slurryability of coal and the rheological behavior of a produced CWS for its intended characteristics. At a time when there is much debate about the end of the age of coal as a primary source of thermal and electrical energy, alternative forms of use that can contribute to the reduction of pollutant emissions, as well as particles, in the atmosphere offer alternatives that may allow us to continue using coal, at least during this transition period until a viable alternative is found. In-depth knowledge of these coal slurries may allow, in the future, the development of similar products produced from fuels derived from biomass, such as charcoal or torrefied biomass.

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Section: Coal-water Slurriesmentioning

confidence: 99%

Potential of Coal–Water Slurries as an Alternative Fuel Source during the Transition Period for the Decarbonization of Energy Production: A Review

Nunes

2020

Applied Sciences

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“…The sludge-containing CWS, called coal sludge slurry (CSS), which is similar to oil, can be burned as fuel in power station boilers, industrial boilers, and furnaces and can be utilized as gasification materials [6,7]. The CSS technology has the following advantages: (a) it does not need to pre-dry the sludge before utilization; (b) the high content of water in the sludge can be transformed into free-flowing water by proper pretreatment, and the water used during CSS preparation is saved; and (c) the energy contained in the sludge is well recycled, and the harmful bacteria are completely killed when CSS is combusted or gasified.…”

Section: Introductionmentioning

confidence: 99%

Improving the slurry fuel preparation performance to recycle municipal sewage sludge by combined alkali and ultrasonication pretreatment

et al. 2016

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Municipal wastewater sludge (hereafter, sludge) is economically recycled by mixing with coal to prepare slurry fuels, called coal sludge slurry (CSS). However, raw sludge needs to be pretreated before being prepared as CSS because of its high viscosity. Alkali and ultrasonication pretreatment can effectively disrupt the sludge flocs and improve slurrying performance. The alkali pretreatment method takes a long time but has a low cost, whereas the ultrasonication pretreatment method needs a high energy input but takes a short time. This study combined these two methods with complementary advantages to reduce the sludge pretreatment time and ultrasonication energy demand to improve the slurrying performance for sludge. Results showed that, compared with only alkali and only ultrasonication, the combined alkali and ultrasonication pretreatment method had stronger effects on reducing slurry viscosity. The characteristic viscosity g c of CSS prepared by raw sludge was 1663.60 mPa s. It was reduced to 1033.44 and 1472.10 mPa s, respectively, after the sludge was only pretreated by NaOH and Ca(OH) 2 at a dosage of 10 % dry sludge (DS) for 2 h, while it was reduced to 1205.43 mPa s after the sludge was only pretreated by ultrasonication of 30 kJ/g DS. After combined pretreatment, g c of CSS was reduced to 774.98 mPa s (NaOH of 10 % DS for 2 h ? ultrasonication of 30 kJ/g DS) and 1083.24 mPa s (Ca(OH) 2 of 10 % DS for 2 h ? ultrasonication of 30 kJ/g DS), respectively. Apparently, the combined method can effectively decrease the alkali dosage or the ultrasonication energy input.

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“…The greatest amount of unburned carbon (35% on average and up to 45%) is recorded in ashes collected from grate boilers (Brown and Dykstra, 1995;Fang et al, 1999). In the case of ashes collected from fluidized bed boilers, the amount of unburned carbon may be comparable or slightly lower (from a few to a dozen or more %) than in the case of pulverized boilers (Bartoňová et al, 2007;Jelonek and Mirkowski, 2015). There is a possibility of a reduction in the amount of unburned carbon in the ashes through the appropriate supply of coal and air to different parts of the boiler (Gao et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The results of numerous studies suggest the special importance of macerals from the inertinite group; macerals with strong high reflectance are crucial for the increased amount of unburned carbon in ashes and slags (Nandi et al, 1977;Tsai and Scaroni, 1987;Crelling et al, 1988;Suárez-Ruiz and Crelling, 2008;Valentim et al, 2013). The high content of macerals from the inertinite group is not always a reason for an increase in unburned carbon (Jelonek and Mirkowski, 2015) When it comes to resistance to pyrolysis, macerals from the inertinite group can be divided into reactive and non-reactive (Kruszewska, 1990). Reactive macerals from the inertinite group are subjected to degassing and combustion.…”

Section: Introductionmentioning

confidence: 99%

Petrographic composition of coals and products of coal combustion from the selected combined heat and power plants (CHP) and heating plants in Upper Silesia, Poland

Mirkowski

Jelonek

2019

International Journal of Coal Geology

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Coal samples and by-products resulting from the combustion process collected from seven combined heat and power (CHP) plants and heating plants located in Upper Silesia, southern Poland, were subjected to petrographic analysis. The coal used as a fuel in these plants was collected from mines of the Upper Silesian Coal Basin; it occurs in a wide range of coalification and has variable quality parameters. The coal is dominated by macerals from the vitrinite group; however, a high content of macerals from the inertinite group has also been observed. Based on petrographic analysis of ash and slags, a highly variable mineral matter content, confirming variable combustion efficiency, has been found. In the case of samples collected from large CHP plants with pulverized and fluidized bed boilers, the mineral matter content is high. The share of mineral matter in combustion products clearly decreases in the case of smaller power plants and heating plants, especially those using grate boilers. The increased content of unburned coal can be explained by the fact that coals of higher rank are often used as fuels in the mentioned plants. The greatest diversity of char forms can be observed in the case of samples collected from small CHP plants. In the case of three samples of slag, collected from small heating plants using grate boilers, additional presence of coke, thermally altered, and unaltered coal has also been found.

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Petrographic and geochemical investigation of coal slurries and of the products resulting from their combustion

Cited by 10 publications

References 34 publications

Potential of Coal–Water Slurries as an Alternative Fuel Source during the Transition Period for the Decarbonization of Energy Production: A Review

Potential of Coal–Water Slurries as an Alternative Fuel Source during the Transition Period for the Decarbonization of Energy Production: A Review

Improving the slurry fuel preparation performance to recycle municipal sewage sludge by combined alkali and ultrasonication pretreatment

Petrographic composition of coals and products of coal combustion from the selected combined heat and power plants (CHP) and heating plants in Upper Silesia, Poland

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