Experimental Study Of Biomass With High Temperature Steam Gasification For Hydrogen-rich Gas

In recent years, high temperature agent gasification (HiTAG) is considered a newdeveloping gasification technology. There are some advantages of this technology, such aswide use of raw materials, high gasification intensity and gasification efficiency. Currently,HiTAG technology could be divided into high temperature air gasification (HTAG) andhigh temperature steam gasification (HTSG). HTSG technology has the advantage of highhydrogen content in the synthesis gas which makes the synthesis gas have higherutilization value. HTSG of biomass has a great development value for hydrogen-rich gaswhich is explored and studied by many scholars. However, this technology is still in thedeveloping stage of related experimental research and theoretical exploration.Firstly, the development situation of HiTAG technology was introduced and thecharacteristics of HTSG technology were analyzed emphatically in the paper. It was alsopointed out that the technology had a promising prospect. Secondly, a experimentalplatform for hydrogen-rich gas was established, which included a high temperature steamgenerating system, a throated-type downdraft gasifier, a gas purification system, a samplegas collection system and a automatic control system. Additionally, the shakedown test ofthe experimental platform was used by pine wood shavings and saw dust. Finally, thegasification performance was evaluated using pelletized biomass which considered theeffects of reaction temperatures (700℃~950℃) and steam flow rates (0.3kg/h~0.9kg/h).Temperature was an important influence factor on the synthesis gas components ofbiomass high temperature steam gasification. When the steam flow rate was0.9kg/h, thefraction of H2increased with the raising of temperature and its value reached the maximum47.76%at950℃. The values of CO, CH4and CO2were23.69%,10.75%and14.80%respectively under this reaction conditions. In addition, the fraction of CnHmalso reachedits minimum0.57%. Steam flow rate was another important parameter on the HTSG ofbiomass. When the steam flow rate increased, the steam partial pressure in the gasifier increased and its can be helpful for the steam related reactions moving in the positivedirection. But, there was an optimal steam flow rate when the rising of steam flow rates.The fraction of syngas which included H2, CO and CH4was in the range of79.50%~85.34%with steam flow rate of0.6kg/h.When the HTSG of biomass in the downdraft gasifier was used, the gasificationreaction heat was supplied by high temperature steam and external heating source, whichstrengthened the course of reaction in the gasifier. And there were no distinct differencesabout drying layer, pyrolysis layer and gasification layer. The gasification layer becamethicker, the gasification intensity became stronger and the synthesis gas became better thanlow temperature steam gasification of biomass. And the effects of reaction temperature andsteam flow rate were considered synthetically. Through the analysis and comparison, thesynthesis gas quality was optimized at900℃with steam flow rate of0.6kg/h. Under theoptimal conditions, synthesis gas low calorific value was14.85MJ/m3and came up thestandards of medium calorific value gas; synthesis gas yield, hydrogen yield and cold gasefficiency reached the maximum with values2.56m3/kg,101.81g/kg,2.07, respectively.