Experimental and Modeling Studies on the Release and Condensation of Inorganics in a Pressurized Biomass Fluidized Bed Gasification Process
Time: Thu 2025-02-13 10.00
Location: LOGOS, Teknikringen 42
Video link: https://kth-se.zoom.us/webinar/register/WN_XIERKif7R1quWK-eodPJuw#/registration
Language: English
Subject area: Chemical Engineering
Doctoral student: Wei Wan , Processteknologi
Opponent: Professor Tobias Richards, Högskolan i Borås
Supervisor: Professor Klas Engvall, Processteknologi; Doktor Weihong Yang, Processer, Tillämpad termodynamik och kylteknik
QC 20250121
Abstract
A major challenge facing society today is the emissions of fossil CO2(g) that strongly contributes to global warming. It is therefore crucial to find ways to reduce these emissions. Biomass is only stored energy, deriving from direct or indirect photosynthesis in plants, and is therefore considered a carbon-neutral fuel. An attractive technology to utilize this stored energy is thermochemical conversion by means of gasification.
During biomass gasification, impurities, such as alkalis, particulates, tars, HCl(g), H2S(g), COS(g), NH3(g), and HCN(g), are released into the gas phase. To find strategies to deal with these impurities in a gasification-based process, the release and condensation of inorganics and tars under different conditions should be investigated.
In this thesis work, a process model of steam/oxygen blown fluid bed gasification, predicting the release and condensation of minor elements (i.e., Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti, and Zn), was developed using SimuSage software. Results of experiments performed in a pilot-scale steam/oxygen blown fluidized bed gasification facility, were used to validate the developed process model and customized thermodynamic database. The process model and customized thermodynamic database were used to study the speciation of inorganics in the condensed phase during gas cooling. The model was improved by combining a model in Aspen Plus with SimuSage, to predict the release of major elements (i.e., C, H, O, N, S, and Cl), using a semi-empirical model. This combined model was also used to investigate the effects of various operating parameters, including gasification temperature, biomass composition, pressure of syngas in downstream processes, and using CO2(g) as a gasification agent, on the fate of inorganics during gasification and downstream processes.