Dehydration and Upgrading of Lignite with Microwave

Abstract:

For solving the problems of high energy consumption and high capacity of water-absorption, microwave dehydration technology of lignite was studied in this paper. A self-developed microwave system was used for the experiment on dehydration of lignite from eastern Inner Mongolia. It was proved that the condition of moisture migration was improved and microwave dehydration had a unique mechanism. By analyzing the effects of microwave powers, coal particle sizes, and lignite qualities on drying characteristics, it was found that the moisture decreased when the microwave power increased. it was found that the higher the power was, the faster the moisture decreased; the smaller the particle size was, the faster the moisture decreased; the less the lignite was, the faster the moisture decreased. Through the scanning electron microscope analysis, it was concluded that microwave had no significant effect on the smooth particles, and the fibrous particles and clusters particles tended to be smooth under the effect of microwave. Therefore, the interface of lignite was relatively stable, and not easy to reabsorb water after microwave.

• Periodical: Applied Mechanics and Materials (Volumes 423-426)
• Pages: 667-673
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.423-426.667
• Online since: September 2013
• Authors: Fan Wen Xin*, Zhi Qiang Xu, Ya Nan Tu, Wei Yang, Xiang Yu Han, Peng Fei Geng
• Keywords: Dehydration, Lignite, Microwave, Oxygen Functional Groups, Pore Structure

References

[1] Karthikeyan M, Zhonghua W, Mujumdar A S. Low-rank coal drying technologies-Current status and new developments [J]. Drying Technology, 2009, 27(3): 403-415.

DOI: 10.1080/07373930802683005

[2] Wan Yongzhou. Study on the mechanism and technology of lignite hot-pressing dehydration [D]. Xuzhou: China University of Mining & Technology, 2012: 10-17. (in Chinese).

[3] Li Xianchun. The study on lignite upgrading and its effect on combustion characteristics [D]. Dalian: Dalian University of Technology, 2011: 4-8. (in Chinese).

[4] Li Pei. Mechanism and economy research on thermal-pressure dewatering for east of Inner-Mongolia lignite [D]. Hangzhou: Zhejiang University, 2011: 10-16. (in Chinese).

[5] Bergins C. Kinetics and mechanism during mechanical/thermal dewatering of lignite [J]. Fuel, 2003, 82(4): 355-364.

DOI: 10.1016/s0016-2361(02)00310-1

[6] Bergins C. Mechanical/thermal dewatering of lignite. Part 2: A rheological model for consolidation and creep process [J]. Fuel, 2004, 83(3): 267-276.

DOI: 10.1016/j.fuel.2003.08.002

[7] Bergins C, Hulston J, Strauss K, et al. Mechanical/thermal dewatering of lignite. Part 3: Physical properties and pore structure of MTE product coals [J]. Fuel, 2007, 86(1): 3-16.

DOI: 10.1016/j.fuel.2006.06.019

[8] Hulston J, Chaffee A L, Bergins C, et al. Comparison of physico-chemical properties of various lignites treated by mechanical thermal expression [J]. Coal Preparation, 2005, 25(4): 269-293.

DOI: 10.1080/07349340500444505

[9] J. Hulston, G. Favas, A.L. Chaffee, Physico-chemical properties of Loy Yang lignite dewatered by mechanical thermal expression [J], Fuel 84 (2005) 1940-(1948).

DOI: 10.1016/j.fuel.2005.03.024

[10] Favas G, Jackson W R. Hydrothermal dewatering of lower rank coals. 1. Effects of process conditions on the properties of dried product [J]. Fuel, 2003, 82(1): 53-57.

DOI: 10.1016/s0016-2361(02)00192-8

[11] Favas G, Jackson W R. Hydrothermal dewatering of lower rank coals. 2. Effects of coal characteristics for a range of Australian and international coals [J]. Fuel, 2003, 82(1): 59-69.

DOI: 10.1016/s0016-2361(02)00191-6

[12] Favas G, Jackson W R, Marshall M. Hydrothermal dewatering of lower rank coals. 3. High-concentration slurries from hydrothermally treated lower rank coals [J]. Fuel, 2003, 82(1): 71-79.

DOI: 10.1016/s0016-2361(02)00190-4

[13] T. Uslu, U. Atalay. Microwave heating of coal for enhanced magnetic removal of pyrite [J]. Fuel Processing Technology 85 (2004) 21-29.

DOI: 10.1016/s0378-3820(03)00094-8

[14] Marland S, Merchant A, Rowson N. Dielectric properties of coal [J]. Fuel, 2001, 80(13): 1839-1849.

DOI: 10.1016/s0016-2361(01)00050-3

[15] Lester E, Kingman S. The effect of microwave pre-heating on five different coals [J]. Fuel, 2004, 83(14): 1941-(1947).

DOI: 10.1016/j.fuel.2004.05.006

[16] Ge L, Zhang Y, Wang Z, et al. Effects of microwave irradiation treatment on physicochemical characteristics of Chinese low-rank coals [J]. Energy Conversion and Management, 2013, 71: 84-91.

DOI: 10.1016/j.enconman.2013.03.021

[17] Cheng J, Zhou JH, Li YC, et al. Improvement of coal water slurry property through coal physicochemical modifications by microwave irradiation and thermal heat [J]. Energy & Fuels, 2008, 22(4): 2422-2428.

DOI: 10.1021/ef7005244

[18] Zhou Junhu, Li Yanchang, Cheng Jun, et al. Research of improving slurrying property of Shenhua coal by microwave pre-heating [J]. Journal of China Coal Society, 2007, 32(6): 617-621. (in Chinese).

[19] Dai Caisheng, Yan Yandong. Experimental study of dehydration of brown coal in Yunnan Province [J]. Mineral Engineering Research, 2012, 1: 59-63. (in Chinese).

[20] Wang Aiying, Cheng Jun, Liu Jianzhong, et al. Effect of microwave on drying and slurryability of lignite [J]. Energy Engineering, 2012, 1: 1-5. (in Chinese).