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Liquefaction of blended coal
Letters to the Editor
Liquefaction
of blended
coal
Yoshiki Sato National Research Institute for Pollution Tsukuba-gun, lba?aki 305, Japan (Received 11 October 1982)
and Resources,
16-3
Onogawa,
Yatabe-cho.
The effect on liquefaction of the blending of two coals of different rank has been evaluated in a conventional autoclave experiment at ~400°C by the solvent-refined coal (SRC) method as well as by short-contact-time hydrogenation at temperatures up to 550°C without solvent and using a specially designed cylindrical autoclave. Using the latter method, higher conversions of coal to gas and liquid, than those calculated by the additivity rule, were observed. (Keywords:
coal;
coal
liquefaction;
yield)
Recently, liquefaction of various types of coal has been studied not only on the laboratory scale but also on the pilot scale to produce new clean fuel.’ -4 The liquefaction of Miike, Taiheiyo (Japanese bituminous and subbituminous coals, respectively) and Newdell coal (Australian bituminous coal) by means of the solventrefined coal (SRC) method’ as well as by hydropyrolysis 6F’ has been reported already. Miike coal gave a higher conversion to liquid than the other coals using both experimental methods. This paper describes an examination of the effect of blending of different types of coal on liquefaction reactivity with or without solvent using a conventional autoclave and a cylindrical autoclave specially designed for short-contact-time hydrogenation. Miike coal (C, 83.5; H, 63 wt% daf; ash, 9.0 wt% db), Taiheiyo coal (C, 75.0; H, 6.4 wt% daf; ash, 11.1 wt% db) and Newdell coal (C, 83.5; H, 5.8 wt%daf; ash, 8.9 wt% db) were crushed and sized to pass 200 Tyler mesh. Liquefaction with solvent was carried out, using a 500 ml autoclave, at 400 and 420°C under a hydrogen pressure of 7.8 MPa. The hydrogenation experiments at short contact time were carried out at 500 and 5%X and a hydrogen pressure of 14.7 MPa using a cylindrical autoclave (3 cm i.d. and 1 m length) equipped with a magnedrive handling device for moving the sample holder with w 1 g of coal, up to the reactor zone from the bottom of the autoclave where the sample was kept cool. The reaction conditions were selected to give the highest conversion to gas and liquid for each coal. Details of the apparatus, experimental procedures and data obtained with the single coals are described in previous papers.5 - ’ The results obtained by the short-contact-time hydrogenation of Miike coal blended with Taiheiyo or Newdell coal at 500 and 550°C with a pressure of 14.7 MPa as shown in Figure I, indicated an interesting feature. Extraction yields with pyridine were lower than those predicted on the basis of additivity when the blending ratios of Miike to the other coals were < 1. The amount of gaseous products consisting mainly of methane was < 10 wt% (dafcoal basis) in all the experiments. This indicates that with the two different types of coal there is a negative interaction on degradation under the conditions used. The extraction yield of the blends containing excess Miike coal (Miike/Taiheiyo or Newdell-4) showed comparable conversions to those obtained from Miike 00162361/82/09087~02%3.00 @ 1982 Butterworth & Co (Publishers)
Ltd.
coal only. This indicates that Taiheiyo and Newdell coals react more when used as part of a blend, their reactivities being similar to that of Miike coal. Liquefaction reactions of the blends in five times the amount of creosote oil (b.p., 250-280°C) were studied at 400 and 420°C under a pressure of 7.8 MPa of hydrogen and for 30 min (Figure 2). There was no appreciable effect on the liquefaction yield and the additivity rule could be applied. The effects of blending two coals may be compensated in the presence of excess solvent. To understand the reaction behaviour observed in the short-contact-time hydrogenation, the liquefaction of Taiheiyo coal, mixed with various amounts of SRC or ash produced from Miike coal, was examined. Assuming that the SRC was still soluble in pyridine after the reaction, the extraction yields of Taiheiyo coal were calculated according to the following equation:
:>~_=--_-Z--_
---
_-e----d,
----
0
5
--. -_ C--
50
0 Concentmtlon
of Mllke cwl
(wt%)
hydrogenation of blending coal. Figure 1 Short-contact-time Hydrogen pressure, 14.7 MPa. -, Extraction yield; - -, gas yield. 0, Miike-Newdell blend: 500°C, 10 s; 0, Miike-Newdell blend: 550°C. 5s;A. Miike-Taiheiyo blend: 550°C. 5s
FUEL,
1982,
Vol 61, September
875
Letters to the Editor 1OOr
Table 1 Effects of additives on short-contract-time hydrogenation of Taiheiyo coal Gas yield Additives SRC,
Ash,
20wt% 40wt% 6Owt% 2Owt% 40wt% 60 wt % 60 wt %a
Extraction yiefdb
Total convarsiono
(wt %, daf basis) 4.2 2.7 3.5 10.0 5.5 6.1 4.9
14.4 41.6 68.0 9.5 9.2 6.6 6.8
18.6 44.3 71.5 19.5 14.7 12.7 11.7
a Ash from Taiheiyo coal b Extraction yield = 1 -
Total pyridine-insoluble material (g, daf)
Taiheiyo coal charged (g, daf) + SRC(gI ’ Total cobversion = gas yield + extraction yield Temperature, 550°C; hydrogen pressure, 14.7 MPa; time, 5 s
0
100
50 Concentration of Mrike cool (wt %)
Figure 2 Liquid-phase reaction of Miike coal blended with Taiheiyo coal. Hydrogen pressure, 7.8 MPa; time, 30 min.‘ .,400”C;o,420°C
Extraction yield = Total pyridine-insoluble material (g,daf) Taiheiyo coal charged (g,daf)
(1)
The yields were similar to those of pure Taiheiyo coal even when the reactant consisted of 40 wt% Taiheiyo coal and 60 wt% SRC produced from Miike coal (Table I). The lower the ratio of SRC to Taiheiyo coal, the lower the calculated extraction yield of Taiheiyo coal. Similarly, the yield decreased with the addition of ash. This behaviour cannot be explained by the assumption that the ash acts as a type of catalyst. The conversion of blended coal is thought to be controlled by the ratio of degradation to polymerization in the reaction system. Addition of SRC or ash was not sufficiently effective to improve the
Structure in a coking microscopy study
coal vitrinite
-
degradation in this case. Lighter compounds, similar to creosote oil, or radical species which are produced from the reactive coal in the reaction system, may accelerate the degradation. In the presence of excess solvent, radicals may react rapidly with the solvent to terminate the chain cycle. The interaction between two different coals should be studied with increasing interest in the detailed structural analysis of liquefied products. The reaction behaviour of blended coals and the addition of reaction initiators would be especially promising subjects as regards coal pyrolysis. REFERENCES Sturm, Jr., G. P., Dooley, J. E., Thomson, J. S., Woodward, P. W. and Vogh, J. W. Am. Chem.Sot. Div. Fuel Chem. Preprints 1980,25(l), 25 Shih, S. S., Angevine, P. J., Heck, R. H. and Sawruk. S. ibid. reference Lp.152 Lytle, J. M., Wood, R. E. and Wiser, W. H. Fuel 1980,59,471 Given, P. H., Schleppy, R. and Sood, A. ibid. reference 3, p. 747 Yamakawa, T., Imuta, K.. Sato. Y.. Yamashita. Y. and Itoh.~H. J. Fuel Sot. Japan 1981,6B, 321. Sato, Y., Imuta, K. and Yamakawa, T. Fuel 1979,58, 322 Sato, Y., Imuta, K. and Yamakawa, T. Fuel 1981,60, 1159
a high resolution
electron
Harry Marsh and David Crawford Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK (Received 26 March 1981; revised 15 April 1982)
A coking vitrinite was oxidized in air at 378 K and subsequently carbonized to 873 K under 230 MPa pressure. The purpose of this treatment was to preserve and examine the structure of the parent vitrinite. The carbonized products were examined by high resolution phase contrast electron microscopy. Analysis of fringe images confirmed directly the sizes of crystallites predicted by X-ray diffraction studies. (Keywords:
coal; instrumental
methods
of analysis;
In 1951 Franklin published the results of her studies of structure in hard (isotropic, non-graphitizing) and soft (anisotropic, graphitizing) carbon as well as her results on 00162361/82/09087603$3.00 0 1982 Butterworth & Co (Publishers) Ltd.
878
FUEL, 1982, Vol 61, September
vitrinite)
anthracites.’ Oberlin and Terriere233 studied structure in anthracites by high resolution electron microscopy and concluded that structures in anthracites were best studied
Liquefaction
of blended
coal
Yoshiki Sato National Research Institute for Pollution Tsukuba-gun, lba?aki 305, Japan (Received 11 October 1982)
and Resources,
16-3
Onogawa,
Yatabe-cho.
The effect on liquefaction of the blending of two coals of different rank has been evaluated in a conventional autoclave experiment at ~400°C by the solvent-refined coal (SRC) method as well as by short-contact-time hydrogenation at temperatures up to 550°C without solvent and using a specially designed cylindrical autoclave. Using the latter method, higher conversions of coal to gas and liquid, than those calculated by the additivity rule, were observed. (Keywords:
coal;
coal
liquefaction;
yield)
Recently, liquefaction of various types of coal has been studied not only on the laboratory scale but also on the pilot scale to produce new clean fuel.’ -4 The liquefaction of Miike, Taiheiyo (Japanese bituminous and subbituminous coals, respectively) and Newdell coal (Australian bituminous coal) by means of the solventrefined coal (SRC) method’ as well as by hydropyrolysis 6F’ has been reported already. Miike coal gave a higher conversion to liquid than the other coals using both experimental methods. This paper describes an examination of the effect of blending of different types of coal on liquefaction reactivity with or without solvent using a conventional autoclave and a cylindrical autoclave specially designed for short-contact-time hydrogenation. Miike coal (C, 83.5; H, 63 wt% daf; ash, 9.0 wt% db), Taiheiyo coal (C, 75.0; H, 6.4 wt% daf; ash, 11.1 wt% db) and Newdell coal (C, 83.5; H, 5.8 wt%daf; ash, 8.9 wt% db) were crushed and sized to pass 200 Tyler mesh. Liquefaction with solvent was carried out, using a 500 ml autoclave, at 400 and 420°C under a hydrogen pressure of 7.8 MPa. The hydrogenation experiments at short contact time were carried out at 500 and 5%X and a hydrogen pressure of 14.7 MPa using a cylindrical autoclave (3 cm i.d. and 1 m length) equipped with a magnedrive handling device for moving the sample holder with w 1 g of coal, up to the reactor zone from the bottom of the autoclave where the sample was kept cool. The reaction conditions were selected to give the highest conversion to gas and liquid for each coal. Details of the apparatus, experimental procedures and data obtained with the single coals are described in previous papers.5 - ’ The results obtained by the short-contact-time hydrogenation of Miike coal blended with Taiheiyo or Newdell coal at 500 and 550°C with a pressure of 14.7 MPa as shown in Figure I, indicated an interesting feature. Extraction yields with pyridine were lower than those predicted on the basis of additivity when the blending ratios of Miike to the other coals were < 1. The amount of gaseous products consisting mainly of methane was < 10 wt% (dafcoal basis) in all the experiments. This indicates that with the two different types of coal there is a negative interaction on degradation under the conditions used. The extraction yield of the blends containing excess Miike coal (Miike/Taiheiyo or Newdell-4) showed comparable conversions to those obtained from Miike 00162361/82/09087~02%3.00 @ 1982 Butterworth & Co (Publishers)
Ltd.
coal only. This indicates that Taiheiyo and Newdell coals react more when used as part of a blend, their reactivities being similar to that of Miike coal. Liquefaction reactions of the blends in five times the amount of creosote oil (b.p., 250-280°C) were studied at 400 and 420°C under a pressure of 7.8 MPa of hydrogen and for 30 min (Figure 2). There was no appreciable effect on the liquefaction yield and the additivity rule could be applied. The effects of blending two coals may be compensated in the presence of excess solvent. To understand the reaction behaviour observed in the short-contact-time hydrogenation, the liquefaction of Taiheiyo coal, mixed with various amounts of SRC or ash produced from Miike coal, was examined. Assuming that the SRC was still soluble in pyridine after the reaction, the extraction yields of Taiheiyo coal were calculated according to the following equation:
:>~_=--_-Z--_
---
_-e----d,
----
0
5
--. -_ C--
50
0 Concentmtlon
of Mllke cwl
(wt%)
hydrogenation of blending coal. Figure 1 Short-contact-time Hydrogen pressure, 14.7 MPa. -, Extraction yield; - -, gas yield. 0, Miike-Newdell blend: 500°C, 10 s; 0, Miike-Newdell blend: 550°C. 5s;A. Miike-Taiheiyo blend: 550°C. 5s
FUEL,
1982,
Vol 61, September
875
Letters to the Editor 1OOr
Table 1 Effects of additives on short-contract-time hydrogenation of Taiheiyo coal Gas yield Additives SRC,
Ash,
20wt% 40wt% 6Owt% 2Owt% 40wt% 60 wt % 60 wt %a
Extraction yiefdb
Total convarsiono
(wt %, daf basis) 4.2 2.7 3.5 10.0 5.5 6.1 4.9
14.4 41.6 68.0 9.5 9.2 6.6 6.8
18.6 44.3 71.5 19.5 14.7 12.7 11.7
a Ash from Taiheiyo coal b Extraction yield = 1 -
Total pyridine-insoluble material (g, daf)
Taiheiyo coal charged (g, daf) + SRC(gI ’ Total cobversion = gas yield + extraction yield Temperature, 550°C; hydrogen pressure, 14.7 MPa; time, 5 s
0
100
50 Concentration of Mrike cool (wt %)
Figure 2 Liquid-phase reaction of Miike coal blended with Taiheiyo coal. Hydrogen pressure, 7.8 MPa; time, 30 min.‘ .,400”C;o,420°C
Extraction yield = Total pyridine-insoluble material (g,daf) Taiheiyo coal charged (g,daf)
(1)
The yields were similar to those of pure Taiheiyo coal even when the reactant consisted of 40 wt% Taiheiyo coal and 60 wt% SRC produced from Miike coal (Table I). The lower the ratio of SRC to Taiheiyo coal, the lower the calculated extraction yield of Taiheiyo coal. Similarly, the yield decreased with the addition of ash. This behaviour cannot be explained by the assumption that the ash acts as a type of catalyst. The conversion of blended coal is thought to be controlled by the ratio of degradation to polymerization in the reaction system. Addition of SRC or ash was not sufficiently effective to improve the
Structure in a coking microscopy study
coal vitrinite
-
degradation in this case. Lighter compounds, similar to creosote oil, or radical species which are produced from the reactive coal in the reaction system, may accelerate the degradation. In the presence of excess solvent, radicals may react rapidly with the solvent to terminate the chain cycle. The interaction between two different coals should be studied with increasing interest in the detailed structural analysis of liquefied products. The reaction behaviour of blended coals and the addition of reaction initiators would be especially promising subjects as regards coal pyrolysis. REFERENCES Sturm, Jr., G. P., Dooley, J. E., Thomson, J. S., Woodward, P. W. and Vogh, J. W. Am. Chem.Sot. Div. Fuel Chem. Preprints 1980,25(l), 25 Shih, S. S., Angevine, P. J., Heck, R. H. and Sawruk. S. ibid. reference Lp.152 Lytle, J. M., Wood, R. E. and Wiser, W. H. Fuel 1980,59,471 Given, P. H., Schleppy, R. and Sood, A. ibid. reference 3, p. 747 Yamakawa, T., Imuta, K.. Sato. Y.. Yamashita. Y. and Itoh.~H. J. Fuel Sot. Japan 1981,6B, 321. Sato, Y., Imuta, K. and Yamakawa, T. Fuel 1979,58, 322 Sato, Y., Imuta, K. and Yamakawa, T. Fuel 1981,60, 1159
a high resolution
electron
Harry Marsh and David Crawford Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK (Received 26 March 1981; revised 15 April 1982)
A coking vitrinite was oxidized in air at 378 K and subsequently carbonized to 873 K under 230 MPa pressure. The purpose of this treatment was to preserve and examine the structure of the parent vitrinite. The carbonized products were examined by high resolution phase contrast electron microscopy. Analysis of fringe images confirmed directly the sizes of crystallites predicted by X-ray diffraction studies. (Keywords:
coal; instrumental
methods
of analysis;
In 1951 Franklin published the results of her studies of structure in hard (isotropic, non-graphitizing) and soft (anisotropic, graphitizing) carbon as well as her results on 00162361/82/09087603$3.00 0 1982 Butterworth & Co (Publishers) Ltd.
878
FUEL, 1982, Vol 61, September
vitrinite)
anthracites.’ Oberlin and Terriere233 studied structure in anthracites by high resolution electron microscopy and concluded that structures in anthracites were best studied