• Journal of Energy Engineering
• /
• v.23 no.2
• /
• pp.1-6
• /
• 2014

Upgrading technology has been studied for efficient utilization of low rank coal. Spray coating of heavy oil was applied on the upgrading process in order to stabilize low rank coal against spontaneous combustion. Low rank coal, which contains more than 30wt% of moisture, was upgraded to high calorific coal and stabilized by spray coating of heavy oil. It was identified that spray coating of heavy oil after drying coal is the optimum procedure of upgrading low rank coal. The experimental results show that more than 2wt% of heavy oil should be adsorbed on the coal in order to stabilize sufficiently for spontaneous combustion.

• Resources Recycling
• /
• v.29 no.2
• /
• pp.37-47
• /
• 2020

According to Vietnam government establishes additional thermal power plant, processing the coal ash from power plant is urgent issue. This study targeted reducing unburned carbon contents in low quality fly ash to below 6% that according to international standards. As a result, the unburned carbon contents of low quality fly ash was high and irregular as 5.3~23.6%, and it was possible to reduce unburned cabon contents to under 6%, in case of unburned carbon contents below 9.8% ashes using air classification, in case of unburned carbon contents below 23.6% ashes using combined process composed of air classification and electrostatic separation.

• Clean Technology
• /
• v.19 no.4
• /
• pp.469-475
• /
• 2013

In this research, the stabilization characteristics of upgraded coal using palm oil residues were investigated. The Eco coal, which is the Indonesian low-rank coal, was used as a raw material. The low-rank coal was mixed with palm fatty acid distillate (PFAD), and then dried in a nitrogen atmosphere at $107^{\circ}C$. The trend of spontaneous combustion of upgraded coal was studied by measuring of crossing-point temperature (CPT), low temperature oxidation and moisture readsorption. The results of the CPT measuring and low temperature oxidation showed that the propensity of spontaneous combustion of the upgraded coal was improved compared to the dried coal. The moisture readsorption characteristics of the upgraded coal was also improved. The upgraded coal was stabilized through the surface coating with PFAD, and stability of upgraded coal was proportional to the content of PFAD.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.23 no.4
• /
• pp.11-20
• /
• 2015

In the present work, a basic study on the in-situ biogenic methane generation from low grade coal bed was conducted. Lignite from Indonesia was used as a sample feedstock. A series of BMP (Biochemical Methane Potential) tests were carried out under the different experimental conditions. Although nutrients and anaerobic digester sludge were added to the coal, the produced amount of methane was limited. Both temperature control and particle size reduction showed little effect on the increase of methane potential. When rice straw was added to lignite as an external carbon source, methane yield of 94.4~110.4 mL/g VS was obtained after 60 days of BMP test. The calorific value of lignite after BMP test decreased (4.5~12.1 %) as increasing the content of rice straw (12.5~50 wt % of lignite), implying that anaerobic digestion of rice straw led to partial degradation of lignite. Therefore, rice straw could be used as an external carbon source for the start-up of in-situ biogas generation from low grade coal bed.

• Journal of Energy Engineering
• /
• v.18 no.4
• /
• pp.213-220
• /
• 2009

The experimental characteristics for fry drying method was investigated using low-rank coal with a high moisture content. Final temperature, mixing ratio between coal and kerosene, content of coal or kerosene, total weight of the mixture and mixing methods were varied to find out the optimum conditions by measuring moisture of coal. Evaporation of the coal moisture was not completed below $120^{\circ}C$ of final temperature. The amount of moisture was not significantly different over $130^{\circ}C$. Coal moisture was easily evaporated by increasing coal content, which showed that the moisture evaporation could be significantly enhanced by the remove of evaporated moisture from kerosene rather than by heat transfer to the coal. High total weight of the mixture resulted in lowering moisture content of coal with long evaporation time. On the other hand, low total weight was difficult to reduce the moisture below a certain level, but could reduce evaporation time. Thus, it can concluded that kerosene content should be lowered to the extent maintaining the mobility of the mixture in order to enhance evaporation. It was also observed that evacuation and mixing by using nitrogen could improve drying of coal.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.25 no.1
• /
• pp.57-65
• /
• 2017

In a column experiment with low rank coal, rice straw was additionally supplied to induce methane gas generation by microorganisms in the state of supplying microorganisms and nutrients, and long-term biogas production characteristics were observed. When the weight ratio of the rice straw to coal was 0.04 or less, there was no significant gas generation. At 0.08, the biogas was generated for about 90 days. However, the methane gas generation was only 5% compared with the vial test result at optimum condition. Therefore, in order to produce biogas in the coal deposit in situ, a reactor that operates at COD concentration of 2000 mg/L or more at a ratio of 1:3 or more of rice straw to coal should be installed on the ground or under the ground. Liquid from the column filled with coal and rice straw and a liquid from vial containing rice straw were analyzed by microbial community analysis using pyrosequencing method, and compared the dominant microbial species among the two samples. In terms of the uniformity and diversity of the bacteria, the coal-filled column showed various species distribution, which has shown to be a disadvantageous microbial distribution to methane production.

• Korean Chemical Engineering Research
• /
• v.53 no.2
• /
• pp.231-235
• /
• 2015

The characteristics of binderless briquettes for dried low-rank coal was studied in this work. Two kinds of Indonesian coals were used to briquette after drying them in electric oven. The characteristics of briquettes have been examined by moisture contents, particle size, hydraulic force, and storing period. The optimum moisture contents of briquettes were observed at between 10 wt% and 15 wt%. The strength of coal briquette was stronger as particle size became smaller. The strength of coal briquette was proportional to the hydraulic force under 300 kN, whereas there was little difference among the briquettes made at more than 300 kN of hydraulic force. The strength of briquettes sharply decreased for a week after produced, and then showed the tendency of converging. The results from this work can be a useful guideline of manufacturing and managing upgraded coal briquettes.

• Journal of Energy Engineering
• /
• v.21 no.4
• /
• pp.325-338
• /
• 2012

Currently, there are the technologically urgent needs of fabricating the hyper coal (HC) based on the approach to extracting mainly effective organics from low rank coals (LRCs), because some industrial countries pursue global sustainability dealing with hot issues such as local energy supply security as well as global warming. In this study, as of the fabrication of clean HCs via LRCs upgrading, we comprehensively review the R&D status of two solvent extraction technologies, namely, Ohm heating (OH) and microwave irradiation (MI) extraction processes on the basis of the performance indicator such as a HC extraction yield.

• Plant Journal
• /
• v.8 no.4
• /
• pp.34-39
• /
• 2012

This study presents how low quality coal combustion affects the desulfurizer draft system by correlating of draft loss in a coal-fired thermal power plant and predicts the stall occurrence time of a booster fan. In case of low quality coal, a lot of coal is needed to generate equivalent output power, thereby the rating of increasing draft loss was faster than designed amount of coal. We surely confirmed that draft loss affects the specific energy of a booster fan strongly. On this basis, it is possible to predict the occurring time of stall for a booster fan from current operation specific energy to stall limit specific energy. This study suggests increasing speed of draft loss in each caloric value and the impact of specific energy at a booster fan, it expects to help safe operating in a thermal power plant.

• Resources Recycling
• /
• v.5 no.2
• /
• pp.45-51
• /
• 1996

Domestic coal contains approximnlely 03 to 7 percentage of sulfur. When the suliur in coal is burned, exhaust gas , nay be thc causc of air pollution problcms as well as acid rain. Thc government dccideil lo strengthen the environmcnlal protection policy a1 the 270 ppm of SO, for the coal-Ered plants and to stari in Ian. 1, 1999. This study was carried out lo rcmove the stlfur and mineral mancrs in the samplw using wet msg~xiic separatol ant1 oil agglomeration apparatus. The rcsults for the wet magnetic separalion showed that the total sulfur removal from Kangnung coal sample was 60.8% with 82.6% combustible recovery. For the results of oil agglomeration testa, combustible recavety, ash nod sulfur rcmovcl horn Maro coal sample were 98.0, 70.9 and 95.7 percent, respectively.