Experimental investigation on an entrained flow type biomass gasification system using coconut coir dust as powdery biomass feedstock

Effects of operating parameters on co-gasification of coconut petioles and refuse-derived fuel

Coconut agro-industry in the western region of Thailand generates a large amount of residues. This study investigated the energy production potential of discarded coconut petioles, with a focus on co-gasification with refuse-derived fuel (RDF). Gasification tests involving petioles, RDFs and their mixtures (25%, 50%, 75% or 100% by weight) were conducted in a laboratory-scale fixed bed reactor. Fuel samples of 5 g were gasified at 700°C-900°C for 60 minutes, using simulated air (79% N₂ to 21% O₂, by volume) as a gasifying agent. Gasification of petioles generated producer gas with lower heating values, estimated at 0.43-0.75 MJ Nm^-3, while RDF produced 0.92-1.39 MJ Nm^-3. Adding greater quantities of RDF to the fuel mixture resulted in an increase in the heating value of the producer gas and cold gas efficiency. The operating temperatures and gasifying-agent flow rates affected the efficiency of process differently, depending on the fuel composition. However, the maximum cold gas efficiency from both fuels was detected in tests conducted at 800°C. In co-gasification and pure refuse-derived-fuel tests, higher temperatures and gasifying-agent flow rates led to outputs with higher energy yields. Our findings suggested that co-gasification of petiole is a viable alternative waste-treatment technology for this region.

Syngas Derived from Lignocellulosic Biomass Gasification as an Alternative Resource for Innovative Bioprocesses

A hybrid system based on lignocellulosic biomass gasification and syngas fermentation represents a second-generation biorefinery approach that is currently in the development phase. Lignocellulosic biomass can be gasified to produce syngas, which is a gas mixture consisting mainly of H2, CO, and CO2. The major challenge of biomass gasification is the syngas’s final quality. Consequently, the development of effective syngas clean-up technologies has gained increased interest in recent years. Furthermore, the bioconversion of syngas components has been intensively studied using acetogenic bacteria and their Wood–Ljungdahl pathway to produce, among others, acetate, ethanol, butyrate, butanol, caproate, hexanol, 2,3-butanediol, and lactate. Nowadays, syngas fermentation appears to be a promising alternative for producing commodity chemicals in comparison to fossil-based processes. Research studies on syngas fermentation have been focused on process design and optimization, investigating the medium composition, operating parameters, and bioreactor design. Moreover, metabolic engineering efforts have been made to develop genetically modified strains with improved production. In 2018, for the first time, a syngas fermentation pilot plant from biomass gasification was built by LanzaTech Inc. in cooperation with Aemetis, Inc. Future research will focus on coupling syngas fermentation with additional bioprocesses and/or on identifying new non-acetogenic microorganisms to produce high-value chemicals beyond acetate and ethanol.

Investigation on the high-temperature flow behavior of biomass and coal blended ash

The high-temperature flow behavior of biomass (straw) and coal blended ash was studied. The variation of viscosity and the temperature of critical viscosity with different straw content were investigated. It is found that the straw ash with high viscosity is unsuitable for directly gasification and the 20% straw content sample can effectively decrease the viscosity. The solid phase content and mineral matters variation calculated by FactSage demonstrate the change of viscosity. In addition, the network theory illustrates that the Si-O-Si bond decreases to improve the viscosity of 20% straw content sample. The variation of mineral matters in XRD analysis validates the change of viscosity. Furthermore, the temperature of critical viscosity and lowest operation temperature reach the minimum when the straw content is 20%. Hysteresis between heating and cooling process of the sample with 20% straw content is more obvious than that of the samples with 40% and 80% straw content.