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Parametric analysis of pyrolysis process on the product yields in a bubbling fluidized bed reactor

Citation

Jalalifar, S and Abbassi, R and Garaniya, V and Hawboldt, K and Ghiji, M, Parametric analysis of pyrolysis process on the product yields in a bubbling fluidized bed reactor, Fuel, 234 pp. 616-625. ISSN 0016-2361 (2018) [Refereed Article]

Copyright Statement

Copyright 2018 Elsevier Ltd.

Official URL: https://www.sciencedirect.com/science/article/pii/...

DOI: doi:10.1016/j.fuel.2018.07.070

Abstract

This paper presents a numerical study of operating factors on the product yields of a fast pyrolysis process in a 2-D standard lab-scale bubbling fluidized bed reactor. In a fast pyrolysis process, oxygen-free thermal decomposition of biomass occurs to produce solid biochar, condensable vapours and non-condensable gases. This process also involves complex transport phenomena and therefore the Euler-Euler approach with a multi-fluid model is applied. The eleven species taking part in the process are grouped into a solid reacting phase, condensable/non-condensable phase, and non-reacting solid phase (the heat carrier). The biomass decomposition is simplified to ten reaction mechanisms based on the thermal decomposition of lignocellulosic biomass. For coupling of multi-fluid model and reaction rates, the time-splitting method is used. The developed model is validated first using available experimental data and is then employed to conduct the parametric study. Based on the simulation results, the impact of different operating factors on the product yields are presented. The results for operating temperature (both sidewall and carrier gas temperature) show that the optimum temperature for the production of bio-oil is in the range of 500–525 °C. The higher the nitrogen velocity, the lower the residence time and less chance for the secondary crack of condensable vapours to non-condensable gases and consequently higher bio-oil yield. Similarly, when the height of the biomass injector was raised, the yields of condensable increased and non-condensable decreased due to the lower residence time of biomass. Biomass flow rate of 1.3 kg/h can produce favourable results. When larger biomass particle sizes are used, the intraparticle temperature gradient increases and leads to more accumulated unreacted biomass inside the reactor and the products’ yield decreases accordingly. The simulation indicated that the larger sand particles accompanied by higher carrier gas velocity are favourable for bio-oil production. Providing a net heat equivalent of 6.52 W to the virgin biomass prior to entering the reactor bed leads to 7.5% higher bio-oil yields whereas other products’ yields stay steady. Results from different feedstock material show that the sum of cellulose and hemicellulose content is favourable for the production of bio-oil whereas the biochar yield is directly related to the lignin content.

Item Details

Item Type:Refereed Article
Keywords:biomass, fast pyrolysis bubbling, fluidized bed reactor, Euler-Euler approach, multi-fluid model, bio-oil
Research Division:Engineering
Research Group:Automotive engineering
Research Field:Automotive combustion and fuel engineering
Objective Division:Transport
Objective Group:Environmentally sustainable transport activities
Objective Field:Environmentally sustainable transport activities not elsewhere classified
UTAS Author:Jalalifar, S (Mr Salman Jalalifar)
UTAS Author:Garaniya, V (Associate Professor Vikram Garaniya)
ID Code:127331
Year Published:2018
Web of Science® Times Cited:12
Deposited By:NC Maritime Engineering and Hydrodynamics
Deposited On:2018-07-22
Last Modified:2018-11-26
Downloads:0

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