“…Up to now, many works have been carried out for the kinetic study of DCL, and various kinetic models have been reported. − Several reaction pathways were tried, and the best pathway was chosen, as shown in Figure . The model included serial and parallel reactions, as shown in the figure.…”
Section: Results
and Discussionmentioning
confidence: 99%
“…To solve the model, the following assumptions were made: (1) First-order irreversible reactions were assumed for all reaction paths. − (2) All of the rate constants fitted the Arrhenius law. (3) The length and inner diameter of the reactor were 12.5 m and 15 mm, respectively.…”
In order to study the direct coal liquefaction in the isothermal stage of Shenhua Shendong bituminous coal, the direct coal liquefaction with iron-based catalyst was carried out in a 0.01t/d continuous tubular facility in the temperature range of 445℃ to 465℃, with hydrogenated anthracene and wash oil as solvent. A 8-lump kinetic model of the isothermal stage was proposed, and the kinetic parameters were estimated. The result showed that in the isothermal stage the oil was mainly obtained from PAA rather than from coal directly. The model was valid for the isothermal stage of direct coal liquefaction.
“…Up to now, many works have been carried out for the kinetic study of DCL, and various kinetic models have been reported. − Several reaction pathways were tried, and the best pathway was chosen, as shown in Figure . The model included serial and parallel reactions, as shown in the figure.…”
Section: Results
and Discussionmentioning
confidence: 99%
“…To solve the model, the following assumptions were made: (1) First-order irreversible reactions were assumed for all reaction paths. − (2) All of the rate constants fitted the Arrhenius law. (3) The length and inner diameter of the reactor were 12.5 m and 15 mm, respectively.…”
In order to study the direct coal liquefaction in the isothermal stage of Shenhua Shendong bituminous coal, the direct coal liquefaction with iron-based catalyst was carried out in a 0.01t/d continuous tubular facility in the temperature range of 445℃ to 465℃, with hydrogenated anthracene and wash oil as solvent. A 8-lump kinetic model of the isothermal stage was proposed, and the kinetic parameters were estimated. The result showed that in the isothermal stage the oil was mainly obtained from PAA rather than from coal directly. The model was valid for the isothermal stage of direct coal liquefaction.
“…Therefore, the increase of the residue yield shown in Figure seems to depend on the increase of the asphaltene fraction. Kidoguchi et al and Itoh et al . have proposed the reaction scheme of the NEDOL process and calculated the reaction rate constant for each reaction path and that, in the initial stage of the liquefaction reaction, heavy oil (623−811 K of boiling range) and asphaltene are formed from coal, and that the asphaltene and heavy oil decompose slowly.…”
A maximum oil yield in the NEDOL coal liquefaction process was obtained with coal containing 76-78% carbon, while gas and water yields decreased with an increase in the carbon content. On the other hand, residue yield increased with an increase in the carbon content and this was attributed to an increase in asphaltene [(hexane insoluble)-(toluene soluble)] in the residue. From the experimental results, it was inferred that decomposition of the asphaltene is inevitable for improvement of the oil yield and that prolonged residence time in the liquefaction reactors is the most effective and practical measure for decomposing the asphaltene under the operating conditions of the NEDOL process. The average structure of the hexane soluble, asphaltene and preasphaltene [(toluene insoluble)-(THF soluble)] in the liquefaction residue exhibited the similar structural parameters in coals tested in the NEDOL coal liquefaction plants. The asphaltene fraction was then extracted from the residue by commercially applicable extraction conditions following which the extract was hydrotreated. About 35% of the extract was recovered as oil, which is lighter than 811K boiling point, by hydrotreatment. Furthermore, coal liquefaction experiments that used the extract as a part of solvent were conducted and an increase in total liquefaction oil yield was confirmed comparing with a coal liquefaction experiment without the extract.
“…The kinetic constants for these reactions were estimated by autoclave reaction tests. Because details have been reported elsewhere, 9 only the main points are addressed in this paper. The coal was pulverized into particles of less than 100 mm in size, and a 3 g sample was suspended in 7 g of the equilibrated recycle solvent, which was produced in the PSU.…”
Section: Simulator For the Preheatermentioning
confidence: 99%
“…The conversion of PAAO to oil was neglected in the simulator for the initial reactions, but a slight conversion might occur. 4 Yields at the outlet of the PSU preheater (from Kidoguchi et al).…”
Direct coal liquefaction test plants have been constructed and successfully operated under
subsidies from the New Energy and Industrial Technology Development Organization. To analyze
the data, which had been collected on these plants, a simulator was constructed for the material
and enthalpy balances in the preheaters and reactors. This simulator was evaluated in a process
supporting unit (PSU) with a capacity of 1 ton of dry coal/day and a pilot plant (PP) with a
capacity of 150 tons of dry coal/day, from the standpoint of vapor−liquid equilibria, reaction
rate constants, and hydrodynamics in the reactors. Reaction rate coefficients were determined
in the PSU by iteration until the calculated yields at the outlet of the third reactor coincided
with the observed data. The kinetic data were then applied to the PP, which was operated under
conditions similar to those of the PSU, and the liquefaction product yields at the outlet of the
third reactor were calculated. The calculated values were in general agreement with the observed
data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
