Modification of coal by subcritical steam: pyrolysis and extraction yields

Graff, R.A.; Brandes, S.D.

doi:10.1021/ef00001a016

Cited by 63 publications

(50 citation statements)

References 4 publications

(4 reference statements)

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“…Low Pressure Experiments=A set of water pretreatment experiments was done at 350°C, for 20 minutes or 180 minutes and 1,000,-2,000 pslg instead of 4,000 psig with the Wyodak subbituminouscoal. This was done to study the effects of water pretreatmentunder lower pressure conditionswhich were more common in previousstudies (Graftand Brandes, 1986Brandes, , 1987Khan, et al, 1989). Additionallow pressure(1000 psig) watei pretreatmentexperiments were done with the Illinoiscoal at 350°C, 180 minutes.…”

Section: _-mentioning

confidence: 99%

Fundamental studies of water pretreatment of coal

Serio¹,

Kroo²,

Solomon³

et al. 1991

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During the past year, a set of water pretreatment experiments was completed on four different coals (Zap, Wyodak, Illinois No. 6, and Pittsburgh No. 8) under two different ranges of conditions (very short and very long pretreatment times). Additional water pretreatment experiments were done with Illinois No. 6 and Pittsburgh seam bituminous coals at selected intermediate points to cover the range of pretreatment behavior. The objective of this work was twofold: 1) to determine how bituminous coals behave during water pretreatment under similar conditions: 2) to verify the effects of water pretreatment on liquefaction yields, which previously hav_ been shown to be different,than expectations, i.e, the conditions which give the highest pyrolysis tar yield relative to the raw coal (short pretreatment times) give the lowest liquefaction yields relative to the raw coal and vice versa.

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Section: _-mentioning

confidence: 99%

Fundamental studies of water pretreatment of coal

Serio¹,

Kroo²,

Solomon³

et al. 1991

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“…They found that the hydrogen bonds of the coals were broken thermally during preheating, resulting in increased total volatiles and tar yields of the coals by 3-4%, compared to those of parent coals. Brandes et al [24] and Graff and Brandes [25] proposed that treatment in steam at 5 MPa from 320 to 360 C gave rise to an increase in total volatile yield due to the decomposition of oxygen functional groups. A study by Serio et al [26] obtained a similar conclusion.…”

Section: Introductionmentioning

confidence: 99%

Combustion and Pollutant Emission Characteristics of Lignite Dried by Low Temperature Air

et al. 2014

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Lignite is a kind of coal that has high moisture content and needs to be dried before being utilized. In this article, a Chinese lignite was dried in air at 120-180 C and the changes in its physical and chemical structures after drying were investigated. The results showed that the pore volume and specific surface area of the lignite decreased after drying. Some of the methylene and methyl groups were oxidized by the oxygen in the drying air, resulting in an increase in oxygen functional groups. The combustion characteristics of the dried coals and parent coal (dry basis) were studied via thermogravimetric analysis. The total volatile yields of the dried coals increased compared to the parent coal. The burnout temperatures of the dried coals were higher than the parent coal, whereas the ignition temperatures stayed almost unchanged. An entrained flow system was set up to study the release of nitrogenous gas products during rapid pyrolysis and combustion. The HCN yields of the dried coals during pyrolysis were higher than that of the parent coal, and a similar trend was found for the NO yield during combustion. The mechanism changes of combustion and pollutant emission characteristics were discussed according to the results of the physical and chemical structure analyses.

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“…[10][11][12] The consensus reached from many studies for catalytic flash pyrolysis is that the catalyst is effective only for the secondary gas phase reaction. 13 Graff et al 14 pretreated coal by subcritical steam before pyrolysis and observed a drastic increase of both total volatile and the tar yield by pyrolyzing a bituminous coal at 900°C. However, Kahn et al could not observe any significant increase when they repeated this method.…”

Section: Introductionmentioning

confidence: 99%

Flash Pyrolysis of Lakhara Lignite Utilizing Effective Radical Transfer

Awan¹,

Tahira²,

Nisar³

2004

J Chinese Chemical Soc

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Flash pyrolysis of raw and tetralin treated coal samples were carried out in nitrogen atmosphere. Two representative coal samples from Lakhra coalmines labeled Lakhra-3 (L3) and Lakhra-6B (L6B) were pyrolyzed in their raw state and after treatment with tetralin. Initial experiments were carried out at 700°C with 2 milligrams of 80 mesh size samples. The main hydrocarbon products detected from both samples were methane, ethylene, ethane, propane, butane, pentane, benzene, toluene and xylene (BTX). The ratio of the total hydrocarbon yield from L3 and L6B raw samples is 1:1.49, respectively, while the relative yield of aliphatic C 1-C5 straight chain products to BTX are 7.65:5.49.Theses differences in product yields clearly indicate the compositional variation between the two samples. The total hydrocarbon yield (C1-C5 +BTX) of tetralin swollen L3 coal and L6B coal was larger than the raw coal at all temperatures, and larger by 50.6% and 32.6%, respectively, at 700°C. The treatment of coal samples has a more pronounced effect on BTX yield than C 1-C5 aliphatic hydrocarbons. BTX yield of tetralin treated L3 coals at 700°C was 3.5 times higher while for L6B coal the BTX yield was 2.1 times higher than the raw samples. These significant increases in hydrocarbons yields can be explain in terms of the suppression of the cross-linking reactions of coal fragments due to the penetration of tetralin in to the micropores of coal, as well as the effective H radicals transfer from tetralin to coal fragments during pyrolysis.

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Modification of coal by subcritical steam: pyrolysis and extraction yields

Cited by 63 publications

References 4 publications

Fundamental studies of water pretreatment of coal

Fundamental studies of water pretreatment of coal

Combustion and Pollutant Emission Characteristics of Lignite Dried by Low Temperature Air

Flash Pyrolysis of Lakhara Lignite Utilizing Effective Radical Transfer

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