Advantages of confining the fountain in a conical spouted bed reactor for biomass steam gasification

A study was carried out on the advantages of inserting a fountain confiner in conical spouted beds for biomass steam gasification and the results (gas yield and composition, tar content, carbon conversion efficiency and H-2 production) are compared with those obtained under conventional spouting regime. The experiments were carried out in a bench scale unit operating in continuous regime under the same gasification conditions in all the configurations (850 degrees C, S/B ratio of 2 and olivine as primary catalyst). The gaseous product was analyzed by on-line gas chromatography and micro-gas chromatography, and the tars by gas chromatography-mass spectrometry. The use of a fountain confiner allows enhancing process versatility, increasing gas velocity over the minimum spouting one, increasing the fountain height and reducing olivine particle size (enhanced fountain regime). Thus, as a result of a better gas-solid contact, tar content was reduced from 49.2 g Nm(-3) without fountain confiner to 20.6 g Nm(-3) under enhanced fountain regime, with the reduction of heavy PAHs being especially remarkable. In the same line, a great improvement in process conversion efficiency was attained under the enhanced fountain regime, with gas production reaching a value of 1.3 m(3) kg(-1) and that of H-2 production 5.0 wt%. (C) 2018 Elsevier Ltd. All rights reserved.