Effect of Tar-adsorbing Particles on Tar Components Generated by Lignite Gasification in a Fluidized Bed Gasifier

In a dual fluidized bed gasifier suitable for gasification of lignite, tar is generated as the raw material is gasified because the gasification reaction has at 1073-1173 K, which is a relatively low temperature, and there is a problem such as tar adhering to the piping of the cooling system in the subsequent stage. In this study, in order to reduce tar in the gasification of lignite, porous alumina particles were applied as a tar adsorbent to the upper stage of a laboratory-scale two-stage fluidized bed gasifier, and the gasification characteristics of the produced gas and the tar components were analyzed and its effect was investigated. From the analysis results of tar components using gas chromatograph mass spectrometry (GC/MS) and field desorption mass spectrometry (FD-MS), the tar components obtained under the respective gasification conditions of pyrolysis and steam were almost no difference, and the main components of tar were polycyclic aromatic hydrocarbons without substituents. It was also found that the main components of tar can be sufficiently identified by GC/MS analysis alone. The application of the porous alumina particles increased the gas yields due to the cracking effect of tar. Furthermore, it was confirmed that the gas yields increased under the steam gasification condition rather than pyrolysis condition, and the gasification reactions were promoted by steam. From these results, it is considered that the porous alumina particles are effective in reducing tar, and as a reformer using this, a dual-type reformer capable of using the tar adsorbent for a long period of time is suitable.