Study on the fate of metal elements from biomass in a benchscale fluidized bed gasifier

Fuel xxx (2011) xxx–xxx Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Study on the fate of metal elements from biomass in a bench-scale fluidized bed gasifier Hong Cui ⇑, Scott Q Turn, Vheissu Keffer, Donald Evans, Thai Tran, Michael Foley Hawaii Natural Energy Institute, University of Hawaii at Manoa, 1680 East–West Road, POST 109, Honolulu, HI 96822, United States a r t i c l e i n f o Article history: Received 26 September 2010 Received in revised form 13 July 2011 Accepted 15 July 2011 Available online August 2011 Keywords: Biomass gasification Syngas Trace elements Fluidized bed gasifier a b s t r a c t Two types of biomass fuel were gasified in a steam atmosphere using a bench-scale fluidized bed reactor Filter char, bed material and the product gas stream were sampled and analyzed for a total of 21 elements including Al, Ca, Fe, K, Mg, Na and Si defined as major elements (ME), and Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, P, Sr, Pb, Ti, V, and Zn defined as trace elements (TE) The effects of the sampling system and gasification system on the measurement were determined Mass balances for ME and TE are reported for individual elements and overall It was found that most ash particles or metal elements can be captured by a silicon carbide candle filter that removes small particles from the gas phase, but some of volatile elements pass through the filter and are present in the gas stream Ó 2011 Elsevier Ltd All rights reserved Introduction Biomass gasification is a carbon neutral technology producing fuel gas or synthesis gas (syngas), which must be cleaned up and qualified for downstream devices such as gas turbines, solid oxide fuel cells (SOFC), or catalysts for liquid chemical/fuel synthesis Contaminants of concern present in the syngas are tar components [1–8], alkali metals [9–16], sulfur [1,6,17–21], and chloride species [11,20–26], as well as trace elements [9,13,15,27–43] Some specific inorganic elements [44], including As, Be, Cl, Cd, Cr, Hg, Na, K, P, Pb, Sb, Se, V, and Zn, which may be present as vapor in syngas at high temperature, have been found to have strong effects on SOFC performance For alkali metals (Na and K), the concentrations are limited to 0.1 ppm or 50 ppb in fuel gas according to specifications for the protection of gas turbine hardware [13,45] A more strict tolerance of