Slagging tendency estimation of aquatic microalgae and comparison with terrestrial biomass and waste

Due to their different growth environments, the slagging problem of aquatic biomass such as microalgae Chlorella vulgaris (C. vulgaris) is different from that of other fuels such as wood, herbaceous biomass and wastes. Three sample groups of microalgae C vulgaris were made into ash after different pretreatment processes: non-washing (NW), water-washing (WW) and acid-washing (AW). The slagging-predictive indices (SI), the ash fusibility temperatures (AFT) and ternary equilibrium phase diagram SiO2-CaO-K2O (SCK) system were applied separately to estimate the slagging tendency of aquatic biomass C. vulgaris, six terrestrial biomasses and six wastes. The results showed that the elemental composition of ash for C. vulgaris differed from that of other biofuels, especially regarding the content of P2O5. The WW and AW methods were effective for potassium and sulfur removal from C vulgaris. The results from SI, AFT and SCK system showed that the three groups of C vulgaris ash had high slagging tendency caused by the high phosphorus content. The results of SCK were consistent with the SI results of R-B/A and R-Fu for biomass and wastes. (C) 2020 Elsevier Ltd. All rights reserved.