Experimental verification of a pilot pyrolysis/split product gasification (PSPG) unit

Abstract

In this study, effectiveness of a thermo-catalytic waste and biomass gasification unit consisting of a pyrolysis stage and a split product gasification stage (PSPG) was verified considering: increase of gas lower heating value (LHV), reduction of gas tar content (GTC), increase of cold gas efficiency (CGE) and carbon conversion efficiency (CCE). The unit consisted of three reactors: an auger pyrolysis reactor (PR), fixed-bed char gasification reactor (CHGR) and fixed-bed secondary catalytic reactor (SCR). A low-cost natural clay-based catalyst and a natural zeolite were used in the secondary catalytic reactor. Tar content in syngas and tar yield were significantly affected by the air split ratio. Splitting air between SCR and CHGR reduced the syngas tar content and gasification tar yield. Suitable equivalence ratio and air split ratio in the studied region were 0.1595 and 0.325, respectively. At these ratios, the highest LHV/GTC value was achieved (2.01), CGE was 62.33%, CCE 80.90%, and feed conversion was 94.15%. Tar concentration in syngas was 3.64 g.Nm−3 and tar yield was 5.21 g kg−1. The lower heating value of syngas was 7.34 MJ.Nm−3. To find overall optimal process conditions, higher equivalence and air split ratios will have to be studied.