Low-temperature gasification of waste tire in a fluidized bed q Gang Xiao a,b, * , Ming-Jiang Ni b , Yong Chi b , Ke-Fa Cen b a Key Laboratory of Clean Coal Power Generation and Combustion Technology of MOE, Thermo-Energy Engineering Research Institute, Southeast University, Nanjing 210096, China b Institute for Thermal Power Engineering, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China article info Article history: Received 14 September 2006 Received in revised form 2 July 2007 Accepted 25 February 2008 Available online 8 April 2008 Keywords: Waste tire Gasification Fluidized bed Syngas Carbon black abstract In order to recovery energy and materials from waste tire efficiently, low-temperature gasification is pro- posed. Experiments are carried out in a lab-scale fluidized bed at 400–800 °C when equivalence ratio (ER) is 0.2–0.6. Low heat value (LHV) of syngas increases with increasing temperature or decreasing ER, and the yield is in proportion to ER linearly. The yield of carbon black decreases with increasing temperature or ER lightly. When temperature is over 600 °C, characteristics of carbon black is similar. When temper- ature is over 700 °C, LHV of syngas rises up lightly with increasing temperature, which indicates that it hardly facilitates gasification any more. It is suitable for tire gasification when temperature is 650– 700 °C and ER is 0.2–0.4. Under this condition, LHV and yield of syngas are about 4000–9000 kJ/Nm 3 and 1.8–3.7 Nm 3 /kg, respectively; surface area and yield of carbon black lie in range of 20–30 m 3 /g and 550–650 g/kg, respectively. The carbon balance of these experiments achieves 85–95% when temper- ature is over 600 °C. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction With increasing vehicles, more and more waste tire is produced in China. The best way to dispose it is to reuse it. Many researches have been involved in this area [1–5], such as remanufacturing for reuse, pyrolysis for oil, direct combustion for heat or electric power, gasification for syngas, etc. Remanufacturing is an economical way to recovery waste tire, but it has to face the stagnant demand [3,6], and finally nonrecov- erable tires need to be disposed by other methods. Pyrolysis is an efficient way to convert waste tire into oil and the yield can reach 35–45% [4,5]; because pyrolysis is an endothermic process, an external heating system is needed, which enhances complexity and investment. Direct combustion is a simple way to dispose waste tire and recovery heat or electric power, but it is not consid- ered to be the most economical way [1,4,7,8]. Gasification by air is an exothermic process. It is considered to be another attractive method to recovery energy and materials efficiently [4,9,10]. Wallman et al. [11] estimate the price of H 2 produced from waste tire based on results of a pilot-plant and comparing that from natural gas, and conclude that it is a compet- itive means. Leung and Wang [12] research on gasification effi- ciency of tire at 550–950 °C, find yield of carbon black and conversion ratio of fixed carbon lie in range of 24–37% and 14– 33%, respectively. Lee et al. [13] investigate the effect of oxygen concentration (0–11%) when waste tire is gasified at 700–880 °C, and discover that oxygen concentration can hardly affect energy conversion ratio, which is limited in range of 0.3–0.35. Phillips [9] reports results of waste tire gasification in a pilot-plant and finds that the yield of tar is far less than that of biomass gasification. It is not economical for gasification at high temperature (above 800 °C) if high temperature cannot facilitate gasification obviously, for more tangible heat will lose at higher temperature. So, low- temperature gasification is probably more attractive option to recovery energy (syngas) and materials (carbon black) from waste tire. Syngas can be used as fuel of gas turbine/engine. Carbon black can be used as a kind of SO 2 absorber directly or as activated car- bon after upgrading [14,15]. In order to find out the suitable condi- tions for low-temperature gasification of waste tire, waste tire is gasified at 400–800 °C when equivalence ratio (ER) is 0.2–0.6. The characteristics of syngas and carbon black are analyzed in de- tail and reported as following. 2. Experimental set-up and methodology The fluidized-bed gasifier is equipped with a steel tube of 30 mm inside diameter and 560 mm height. It is placed in an 0196-8904/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2008.02.016 q Foundation item: Specialized Research Fund for the Doctoral Program of Higher Education of China (NO. 20070286074). Open Foundation of State Key Laboratory of Clean Energy Utilization of China (ZJUCEU2006004), Hi-tech Research and Devel- opment Program of China (863 Program, 2006AA020101), National Basic Research Program of China (973 Program, 2005CB221202 and 2007CB210208). National Natural Science Foundation of China (50776019). * Corresponding author. Address: Key Laboratory of Clean Coal Power Generation and Combustion Technology of MOE, Thermo-Energy Engineering Research Insti- tute, Southeast University, Nanjing 210096, China. Tel.: +86 25 8379744; fax: +86 25 83795508. E-mail address: xiaogangtianmen@seu.edu.cn (G. Xiao). Energy Conversion and Management 49 (2008) 2078–2082 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman