For obtaining high shale oil yield as well as treating shale char efficiently and in an environmentally friendly way in a new comprehensive utilization system of oil shale, a series of fundamental experiments have been conducted for exploring the effects of retorting factors on shale oil yield and shale char characteristics. Based on these previous studies, in this article, combustion experiments of shale chars obtained under various retorting conditions were performed with a Q5000IR thermogravimetric analyzer and a Leitz II-A heatable stage microscope and the effects of retorting factors were discussed on the combustion characteristics of shale char. Among four studied retorting parameters, retorting temperature and residence time exert very significant influence on the combustion characteristics of shale char. Either elevating the retorting temperature from 430 to 520 °C or lengthening the residence time at a low retorting temperature will largely decrease residual organic matters within shale char, resulting in decreasing mass loss in the low-temperature stage of combustion process of shale char, an elevation of ignition temperature and a shift of ignition mechanism from homogeneous to heterogeneous. One set of retorting condition was also recommended as a reference for designing the comprehensive utilization system of oil shale studied in this work: retort temperature of 460–490 °C, residence time of 20–40 min, particle size of <3 mm, and low heating rate of <10 °C/min.
1. Qian JL , Wang JQ, Li SY. World’s oil shale available retorting technologies and the forecast of shale oil production. In: Proceedings of the eighteenth international offshore and polar engineering conference, 6-11 July, 2008, Vancouver, Canada, p. 19–20.
2. Trikkel, A, Kuusik, R, Maljukova, N. Distribution of organic and inorganic ingredients in Estonian oil shale spent shale. Oil Shale 2004 21:227–236.
3. Kuusik, R, Martins, A, Pihu, T, Pesur, A, Kaljuvee, T, Prikk, A et al. 2004 Fluidized-bed combustion of oil shale retorting solid waste. Oil Shale 21:237–248.
4. Han, XX, Jiang, XM, Cui, ZG. Study of the combustion mechanism of oil shale semicoke in a thermogravimetric analyzer. J Therm Anal Calorim 2008 92:595–600 .
5. Lyon, RK, Hardy, JE. Combustion of spent shale and other nitrogenous chars. Combust Flame 1983 51:105–107 .
6. Jiang, XM, Han, XX, Cui, ZG. New technology for the comprehensive utilization of Chinese oil shale resources. Energy 2007 32:772–777 .
7. Jiang, XM, Han, XX, Cui, ZG. Progress and recent utilization trends in combustion of Chinese oil shale. Prog Energy Combust Sci 2007 33:552–575 .
8. Han, XX, Jiang, XM, Cui, ZG. Studies of the effect of retorting factors on the yield of shale oil for a new comprehensive utilization technology of oil shale. Appl Energy 2009 86:2381–2385 .
9. Han, XX, Jiang, XM. Effects of retorting factors on combustion properties of shale char. 1. Pyrolysis characteristics. Energy Fuels 2009 23:677–682 .
10. Han, XX, Jiang, XM, Cui, ZG, Liu, JG, Yan, JW. Effects of retorting factors on combustion properties of shale char. 3. Distribution of residual organic matters. J Hazard Mater 2010 175:445–451 .
11. Han XX , Jiang XM, Cui ZG, Liu JG, Yan JW. Effect of retorting parameters on pore structure of Dachengzi oil shale char. Submitted to Energy Fuels. 2010.
12. Kök, MV, Iscan, AG. Oil shale kinetics by differential methods. J Therm Anal Calorim 2007 88:657–661 .
13. Kök, MV. Heating rate effect on the DSC kinetics of oil shales. J Therm Anal Calorim. 2007;90:817–821 .
14. Yağmur, S, Durusoy, T. Kinetics of the pyrolysis and combustion of Goynuk oil shale. J Therm Anal Calorim 2006 86:479–482 .
15. Degirmenci, L, Durusoy, T. Effect of heating rate and particle size on the pyrolysis of Goynuk oil shale. Energy Sources 2005 27:787–795 .
16. Yağmur, S, Durusoy, T. Kinetics of combustion of oil shale with polystyrene. J Therm Anal Calorim 2009 96:189–194 .
17. Aboulkas, A, El Harfi, K, El Bouadili, A, Nadifiyine, M, Benchanaa, M. Study on the pyrolysis of Moroccan oil shale with poly (ethylene terephthalate). J Therm Anal Calorim 2009 96:883–890 .
18. Kaljuvee T , Keelmann M, Trikkel A, Kuusik R. Thermoxidative decomposition of oil shales. J Therm Anal Calorim. 2010. doi: .
19. Arenillas, A, Rubiera, F, Arias, B, Pis, JJ, Faundez, JM, Gordon, AL et al. 2004 A TG/DTA study on the effect of coal blending on ignition behaviour. J Therm Anal Calorim 76:603–614 .
20. Kök, MV. Temperature-controlled combustion and kinetics of different rank coal samples. J Therm Anal Calorim. 2005;79:175–180 .
21. Kök, MV. Thermal analysis applications in fossil fuel science: literature survey. J Therm Anal Calorim. 2002;68:1061–1077 .
22. Krishnaswamy, S, Bhat, S, Gunn, RD, Agarwal, PK. Low-temperature oxidation of coal 1. A single-particle reaction-diffusion model. Fuel 1996 75:333–343 .
23. Kök, MV, Pokol, G, Keskin, C, Madarasz, J, Bagci, S. Combustion characteristics of lignite and oil shale samples by thermal analysis techniques. J Therm Anal Calorim 2004 76:247–254 .
24. Vantelon, JP, Breillat, C, Gaboriaud, F, Alaoui-Sosse, A. Thermal degradation of Timahdit oil shales. Behaviour in inert and oxidizing environments. Fuel 1990 69:211–215 .
25. Wen, CS, Kobylinski, TP. Low-temperature oil shale conversion. Fuel 1983 62:1269–1273 .
26. Tiikma, L, Zaidentsal, A, Tensorer, M. Formation of thermobitumen from oil shale by low-temperature pyrolysis in an autoclave. Oil Shale 2007 24:535–546.
27. Miknis, FP, Turner, TF, Berdan, GL, Conn, PJ. Formation of soluble products from thermal decomposition of Colorado and Kentucky oil shales. Energy Fuels 1987 1:477–483 .