Towards practical application of gasification: a critical review from syngas and biochar perspectives

Abstract

Syngas and biochar production are mainly influenced by temperature, feedstock properties, gasifying agent, pressure, and the mass ratio between gasifying agent and feedstock with temperature being the most significant factor. Increasing temperature generally promotes syngas production while suppressing biochar production. The selection of gasifiers (fixed bed, fluidized bed, and entrained flow) is highly dependent on scale requirement (e.g., volume of feedstock and energy demand), feedstock characteristics (e.g., moisture and ash content), and the quality of syngas and biochar. Updraft fixed bed gasifiers are suitable for the feedstocks with a moisture content up to 50 wt.%. High ash feedstocks such as Indian coal, dried sewage sludge, and municipal solid waste that are not suitable for fixed bed gasifiers, have been successfully gasified in bubbling fluidized bed reactors. Woody biomass is not suitable for entrained flow gasifiers unless specialized feeding methods are employed such as wood torrefaction and grinding followed by the existing feeding methods for pulverized coals, biomass-oil biochar slurry preparation followed by pumping, wood or torrefied wood slurry preparation followed by pumping, etc. Syngas and biochar can potentially be contaminated by NH3, H2S, and tar, which can be removed using catalysts (e.g., Ni-based), metal oxides-based sorbents, and thermal and catalytic cracking methods. Existing syngas and biochar upgrading methods suffered from various problems such as economic infeasibility, limited productivity, and fouling, and future syngas and biochar upgrading methods should be aimed to have the features of reliability, security, affordability, and sustainability, towards the practical, largescale production of syngas-and biochar-based products. One potential solution is to develop integrated systems by combining biochar upgrading and application with syngas upgrading, which warrants an integrated perspective based on both life cycle assessment and economic analysis.

Biochar composition-dependent impacts on soil nutrient release, carbon mineralization, and potential environmental risk: A review

“…Each biochar produced from a specific feedstock using a specific production method (e.g., pyrolysis, gasification, and hydrothermal carbonization) using a specific temperature and with/without an activation or modification process will yield a unique biochar material (Igalavithana et al, 2017a;Yoo et al, 2018;You et al, 2017You et al, , 2018El-Naggar et al, 2019).…”

Visualizing the emerging trends of biochar research and applications in 2019: a scientometric analysis and review

“…(Lehmann and Joseph 2015). The strategies for biochar production include slow and fast pyrolysis, flash carbonization (Uchimiya et al 2015), gasification (You et al 2018), hydrothermal carbonization (Kambo and Dutta 2015), and torrefaction (Kung et al 2019). The most common methods used for biochar fabrication include slow pyrolysis and hydrothermal carbonization.…”

Thermal Effects of Natural Gas and Syngas Co-Firing System on Heat Treatment Process in the Preheating Furnace

“…0.7 MW on average). The lower heating value of a typical syngas produced by this type of gasifiers fluctuates in the range of 3-7 MJ/m 3 N [18]. As one of the adopted objectives to achieve higher efficiency of the co-firing system is to preserve the initial high temperature of syngas, it was assumed that the SG produced by the gasifier is not cooled down on the way to the furnace, and it enters the dedicated burners at 600 • C (873 K).…”