Particulate matter emission and K/S/Cl transformation during biomass combustion in an entrained flow reactor Xuebin Wang a , Zhongfa Hu a , Adewale Adeosun b , Bin Liu c , Renhui Ruan a , Shuaishuai Li a , Houzhang Tan a, * a MOE Key Laboratory of Thermo-Fluid Science and Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China b Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA c China IPPR International Engineering Company Limited, Beijing, 100089, China article info Article history: Received 16 August 2017 Received in revised form 4 October 2017 Accepted 9 October 2017 Available online xxx Keywords: Biomass combustion Fine particle Sulfur High temperature Potassium abstract This study aims to demonstrate the effect of ash chemistry, especially, the transformation of potassium (K), chlorine (Cl), and sulfur (S) species, on the fine particle emission during biomass combustion. Biomass was burned in an entrained flow reactor at varied temperature from 1000 to 1300  C, where fine particles were sampled using a 13-stage low pressure impactor, and the morphology and composition of the fine particles were analyzed. The fates of K, Cl, and S during biomass combustion were compared between the entrained flow reactor and the muffle furnace. Results show that the particle size distri- butions of PM 10 are bimodal for all studied cases. A higher concentration of fine-mode particle is observed at 1000  C, with the peak position at 0.274 mm. When the temperature is increased from 1000 to 1100  C or higher, the concentration of fine-mode particle is reduced by about 50%, and its size be- comes smaller with a peak position at 0.097 mm. K, Cl and S are enriched as potassium chloride and sulfate, dominantly in PM 1.0 ; while Mg, Ca and Si are enriched in PM 1.0e10 . A certain amount of sulfur in PM 1.0 at 1000  C is observed, while the sulfur disappears above 1100  C. This indicates that the process of potassium sulfation tends to occur at a moderate temperature, and affects the emission amount and the particle size distribution of particulate matters. Analyzing results of the fates of K, Cl and S in the particle phase indicate a completed sulfur-release from biomass ash above 1200  C, as well as a maximum capture efficiency for potassium-containing vapors at 1100  C, which results in a minimum PM 1.0 emission at 1100  C. © 2017 Energy Institute. Published by Elsevier Ltd. All rights reserved. 1. Introduction Biomass is regarded as a renewable and alternative fuel because of its net reduction in CO 2 and SOx/NOx emissions [1e3]. Billions of tons of biomass in China per year are of great potentials for reducing fossil fuel utilization and ensuring energy supply security. According to the latest Chinese government five-year biomass utilization plan, the expected development goal of biomass-fired power plants is to reach the total installed capacity of 15 GW at the end of 2020, and at presently the installed capacity of biomass-fired power plants in China is over 10 GW. However, biomass combustion in conventional boilers faces hugechallenge because high contents of alkali metal and chlorine in biomass induce severe problems of ash deposition, fouling, slagging, corrosion, thus leading to negative impact on boiler efficiency [4e6]. Most of the alkali metal and chlorine species are released into the flue gas in the flame zone [7,8]. After undergoing several processes including gas phase reaction, nucleation, and coagulation in the post-flame region, biomass combustion produces a large numbers of aerosols rich in alkali chlorides and sulfates [9,10]. These fine aerosols tend to adhere on the surface of heat exchanger, and initiates ash deposition of large ash particle. Apart from promoting deposition, fine aerosols are difficult to capture by the conventional gas cleaning devices, and then are directly emitted into the atmosphere environment [11]. * Corresponding author. E-mail addresses: wxb005@mail.xjtu.edu.cn (X. Wang), tanhz@mail.xjtu.edu.cn (H. Tan). Contents lists available at ScienceDirect Journal of the Energy Institute journal homepage: http://www.journals.elsevier.com/journal-of-the-energy- institute https://doi.org/10.1016/j.joei.2017.10.005 1743-9671/© 2017 Energy Institute. Published by Elsevier Ltd. All rights reserved. Journal of the Energy Institute xxx (2017) 1e10 Please cite this article in press as: X. Wang, et al., Particulate matter emission and K/S/Cl transformation during biomass combustion in an entrained flow reactor, Journal of the Energy Institute (2017), https://doi.org/10.1016/j.joei.2017.10.005