Visualization of solid distribution with heterogeneity inside fixed bed gasifier
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ORIGINAL ARTICLE
Visualization of solid distribution with heterogeneity inside fixed bed gasifier Hajime Yasuda1 · Takahiro Murakami1 Received: 5 September 2019 / Accepted: 23 April 2020 © Springer Japan KK, part of Springer Nature 2020
Abstract Fixed bed gasifiers are frequently used for biomass gasification as they have a relatively high efficiency for the conversion biomass to syngas, on a small scale. The distribution of solid particles inside a fixed bed gasifier is usually heterogeneous. This distribution is unknown as the currently used reactions cause the particles to continuously change states. A novel gasi‑ fier has been designed to investigate the distribution of these particles inside the gasifier. An opening system at the bottom of the gasifier was equipped to collect particles, without affecting the shapes and positions of the particles remaining inside the gasifier after quenching, at any given point of operation. Because only the bottom of the reactor is opened, the distribution of particles inside the gasifier can be known without the need for transportation, tilting, or splitting of the reactor itself. The gasification performance of this novel gasification system was investigated by varying the distribution of different particles inside the gasifier. Different phenomena, such as product gas distribution were observed during the operation of the gasifier. These phenomena were confirmed by direct observation, using the novel collection/visualization system for solid particles inside the gasifier. Keywords Gasifier · Fixed bed · Moving bed · Observation · Particle
Introduction Gasification is a promising process for the conversion of bio‑ mass to energy and other useful chemicals via combustible gases as the reaction products. Fixed bed gasifiers, used for the conversion of biomass, have a relatively high conver‑ sion efficiency on a small scale. A solid biomass particle can reside in a fixed bed gasifier for several tens of minutes to more than an hour with changing incrementally to ash residue. Therefore, the distribution of solid particles inside the fixed bed gasifier is heterogeneous, particularly in the vertical direction. Several layers, such as a combustion layer, gasification layer, pyrolysis layer, and drying layer are usu‑ ally formed. Also, the horizontal direction, differences in particle distribution may also occur between the center of the layer and near the wall in some cases. Parameters such as the type of biomass used, gasification conditions, and * Hajime Yasuda yasuda‑[email protected] 1
National Institute of Advanced Industrial Science and Technology (AIST), 16‑1 Onogawa, Tsukuba 305‑8569, Japan
distribution, and composition of the solid particles inside the gasifier are proposed as possible variables that might influence this particle distribution. Thus, a change in these variables would affect the particle distribution also affecting the product gas composition and/or temperature distribution in the gasifier, even in the horizontal direction. It is believed that the
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