Hueon Namkung

Coal fouling characteristic to deposit probe with different temperatures under the gasification condition

Coal gasification was carried out to verify the coal fouling characteristic in a drop tube furnace (DTF). Four pulverized coal samples, in the range of bituminous and sub-bituminous, were used. To analyze the fouling characteristic by different temperature of deposit probe, a two-stage deposit probe was used in the experiment. Ash deposition rate was at upper deposit probe higher than at lower one. The X-ray fluorescence (XRF) results indicated that coal fouling included acid minerals such as SiO2 and Al2O3 at upper deposit probe more than that at lower deposit probe. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the fouling particles at high deposit temperature were agglomerated more than those at low deposit temperature. And the convective heat transfer efficiency was reduced by ash deposition on probe. Especially, the convective heat transfer coefficient substantially declined with small particle size of fouling and Fe2O3, CaO, and MgO.

Experimental Study on Drying of Low Rank Coal by Changed Temperature and Particle Size

Nowadays, coal plays an essential role in our global energy mix. With the increasing energy costs and dwindling supplies of petroleum and natural gas, low rank coal has been becoming more and more attractive and practicable, which accounts around 45% of the world’s coal reserves and is cheaper than other fossil fuels. However, low rank coal such as lignite contains 30–60% moisture content and 25–40% volatile matter have kept it from being aggressively exploited until recently. Therefore, how to reduce the moisture content of low rank coal has been an increasingly necessary to solve. The objective of this paper is to obtain appropriate parameters of drying of low rank coal using the heating method. This drying process is heated by Electronic Moisture Balance (EMB) method through changing temperature and particle size. We choose three different particle sizes as the experimental samples to conduct this experiment at three different temperatures. According to the analysis of this experiment and the TGA results, we conclude that the optimal temperature of causing to a dramatically decrease of moisture content is at 107 � C and the drying time of low rank coal is set as 30 min, the three different particle sizes which are chose in this experiment and are less than 3 mm have no distinctive drying effect at 80, 107, 150 � C, respectively, the optimal drying temperature range of low rank coal is from 103 to 123 � C and the drying rate accelerates with the increasing of the temperature which is in agreement with the theory of convection heat flux.

Drying Kinetics Characteristic of Indonesia Lignite Coal (IBC) Using Lab Scale Fixed Bed Reactor

Recent instability of energy market arouse a lot of interest about coal which has a tremendous amount of proven coal reserves worldwide. South Korea hold the second rank by importing 80 million tons of coal in 2007 following by Japan. Among various coals, there is disused coal. It’s called Low Rank Coal (LRC). Drying process has to be preceded before being utilized as power plant. In this study, drying kinetics of LRC is induced by using a fixed bed reactor.

Study on deposition tendency of coal ash under various gasification environments through DTF

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Prediction of coal fouling using an alternative index under the gasification condition

One of the major operation obstacles in gasification process is ash deposition phenomenon. In this investigation, experiment was carried out to examine coal fouling characteristics using a laminar DTF (Drop Tube Furnace) with variation of operating condition such as different coal size, and probe surface temperature. Four different samples of pulverized coal were injected into DTF under various conditions. The ash particles are deposited on probe by impacting and agglomerating action. Fouling grains are made of eutectic compound, which is made by reacting with acid minerals and alkali minerals, in EPMA (Electron Probe Micro-Analysis). And agglomeration area of fouling at top layer is wide more than it of middle and bottom layer. The major mineral factors of fouling phenomenon are Fe, Ca, and Mg. The deposition quantity of fouling increases with increasing particle size, high alkali mineral (Fe, Ca, and Mg) contents, and ash deposition temperature.