Short-Residence-Time Coal Liquefaction

Longanbach, J.R.; Droege, J.W.; Chauhan, S.P.

doi:10.1021/bk-1980-0139.ch008

Cited by 3 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results show that the temperature has a strong positive effect on the production of THF solubles (see Table 10). Whitehurst et al (1977), Longanbach et al (1978), and Traeger et al (1979) have also reported a very fast increase in the formation of THF solubles for times u p to 4 min.…”

Section: A Effect Of Temperaturementioning

confidence: 89%

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

et al. 1984

View full text Add to dashboard Cite

show abstract

Section: A Effect Of Temperaturementioning

confidence: 89%

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

et al. 1984

View full text Add to dashboard Cite

show abstract

“…A variation on this concept was proposed before, whereby the total coal-solvent slurry was passed through the fired heater, but not the liquefaction reactor. , It was demonstrated that by rapid preheating of bituminous coal in tetralin to 390–422 °C an extract yield of the order 20–35% could be obtained within 2 s . This work was later extended to include subbituminous and lignite coals, with analogous results .…”

Section: Resultsmentioning

confidence: 90%

“…A variation on this concept was proposed before, whereby the total coal-solvent slurry was passed through the fired heater, but not the liquefaction reactor. 17,18 It was demonstrated that by rapid preheating of bituminous coal in tetralin to 390− 422 °C an extract yield of the order 20−35% could be obtained within 2 s. 19 This work was later extended to include subbituminous and lignite coals, with analogous results. 20 In all instances the temperature to which the coal was heated for short contact time dissolution was well within the temperature range where reactive decomposition of the coal took place.…”

Section: Extract Yield During Low Temperature Coal Dissolution 321 Co...mentioning

confidence: 93%

Direct Coal Liquefaction: Low Temperature Dissolution Process

Haghighat

Klerk

2014

Energy Fuels

View full text Add to dashboard Cite

The front-end design of a direct coal liquefaction process for the conversion of lignite into coal liquids by solvent extraction was investigated. The experimental work focused on physical coal dissolution in the temperature range 25−150°C. It was found that the kinetics of physical coal dissolution was rapid and essentially complete within 2 min at 25°C. There was a limiting extract yield, which increased with increasing temperature. Within the pore diameter range 0.1−10.7 μm, the volume of only pores with diameters <5 μm increased measurably on solvent extraction, while the shape of the pore size distribution remained the same. Additional pore volume created during extraction exceeded that of the liquid extract. Extraction took place from the bulk of the coal. Packed bed extraction was more efficient than batch extraction at otherwise similar conditions; an explanation was proposed. Even at the least severe conditions, 25°C for 2 min, mass transport was not limiting and the solventto-coal ratio did not meaningfully affect the extract yield. These observations were employed to propose potential improvements to the front-end design for direct coal liquefaction.

show abstract

“…The work also suggests that future industrial development of DCL processes should revisit process concepts based on short contact time liquefaction. ,, It was shown that, at short contact times, both physical and chemical dissolution contributes to a high initial liquefaction yield. , Although overall coal conversion can be improved, this is accompanied by a deterioration in product quality and, in the case of catalytic liquefaction, increased hydrogen consumption . It was found that longer residence time hydrogen disproportionation undermined coal liquid quality (Figure ).…”

Section: Discussionmentioning

confidence: 97%

“…The work also suggests that future industrial development of DCL processes should revisit process concepts based on short contact time liquefaction. 2,18,19 It was shown that, at short contact times, both physical and chemical dissolution contributes to a high initial liquefaction yield. 20,21 Although overall coal conversion can be improved, this is accompanied by a deterioration in product quality and, in the case of catalytic liquefaction, increased hydrogen consumption.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Effect of Direct Coal Liquefaction Conditions on Coal Liquid Quality

et al. 2015

View full text Add to dashboard Cite

Solvent extraction of coal was investigated with a focus on the quality of the coal liquids rather than coal conversion. The aim was to determine how the hydrogen/carbon ratio and other quality measures were influenced by liquefaction conditions. Liquefaction was performed using Canadian Bienfait lignite in the temperature range of 350−450°C, 4 MPa H 2 , solvent/coal ratio of 2:1, and residence times up to 30 min at liquefaction temperature. An industrial hydrotreated coal liquid was used as the solvent. The hydrogen/carbon ratio of the coal liquids decreased with an increase in coal conversion, so that coal liquid quality decreased with an increase in the maximum liquefaction temperature. Selective extraction of hydrogen-rich material during the initial stages of liquefaction could be explained in terms of the low solubility parameter of the solvent, the weaker association of less polar molecules, and the limited extent of hydrogen transfer between phases. At longer residence times, especially at higher temperature, the coal liquids became heavier (>550°C boiling material) and more aromatic and had a higher density and refractive index. These changes were partly due to increased coal conversion and partly due to increased time for hydrogen transfer, cracking, and recombination reactions to take place. It was further found that the nitrogen content of the coal liquids increased with increasing temperature and residence time. Some industrial implications of the changes in coal liquid quality on process development for coal liquefaction were discussed.

show abstract

Short-Residence-Time Coal Liquefaction

Cited by 3 publications

References 0 publications

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

Direct Coal Liquefaction: Low Temperature Dissolution Process

Effect of Direct Coal Liquefaction Conditions on Coal Liquid Quality

Contact Info

Product

Resources

About