Rice straw gasification was carried out in a laboratory fluidized bed reactor system from 600 to 800 • C in order to well-understand the release and occurrence mode of alkali metals as a function of temperature during the gasification process. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was applied to analyze the original rice straw and obtained fly ash at different temperatures. The results show that the Water-Soluble, Ammonium acetate-Soluble, Hydrochloric acid-Soluble, and Aluminosilicate Combination-Soluble modes of the Na and K contents in rice straw decreased in sequence. The content of Water-Soluble salts of Na and K accounts for more than 50%, while the content of the Aluminosilicate Combination-Soluble mode is the lowest: less than 5%. The release rate of Na appears to be consistent but nonlinear, increasing with gasification conversion ranges between 50.2% and 70.8%, from which we can deduce that temperature is not the only factor that impacts Na emission. The release of K can be divided into two stages at 700 • C. At the first stage, the release rate of K is almost invariable, ranging from 23.3% to 26%. At the second stage, the release rate increases sharply: up to 55.9%. The concentration and the proportion of the Water-Soluble, Ammonium acetate-Soluble, and Hydrochloric acid-Soluble modes of Na in fly ash decrease with a temperature increase. The release of K can be explained as follows: one path is an organic form of K converted into its gaseous phase; the other path is a soluble inorganic form of K that is volatile at a high temperature. With a temperature increase, the Aluminosilicate Combination-Soluble mode of both Na and K increases.

Oxygen-enriched gasification of single-feed refuse-derived fuel (RDF) and dry sewage sludge (DSS) in a laboratory-scale fluidized bed was investigated. The optimal temperature, equivalence ratio (ER), and oxygen concentration of RDF and DSS gasification were 800 °C, 0.292, 50% and 750 °C, 0.321, 44.7%, respectively. The low heating values (LHVs) and cold gas efficiency (η values) of syngases from RDF and DSS were 6.79 MJ/Nm 3 , 53.0% and 6.51 MJ/Nm 3 , 49.2%, respectively, under optimal conditions. To improve the quality of DSS syngas, the effect of the RDF mixing ratio on RDF and DSS cogasification was investigated at 800 °C, with an ER of 0.321 and an OC of 44.7%. The gas yield increased continuously with increased RDF mixing ratio, and η rose to 55.0% with relatively high LHV of producer gas at a 25% mixing ratio of RDF.