• Agricultural and Biosystems Engineering
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• v.3 no.2
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• pp.79-84
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• 2002

The seawater involving diverse chemical elements was mixed with wasted coals to improve the quality. The thermal and chemical characteristics of these seawater-mixed coals were investigated and compared with those of original coals. The contents of MgO, $Na_2O$, and $K_2O$ were increased by mixing seawater in wasted coals. The content of $Na_2O$ in these coal samples was greatly increased due to the sodium, which was the main component of seawater. Thus, it was expected that fusion temperatures of these coal samples were decreased. Coal samples mixed with seawater showed that the rapid weight loss was started at the lower temperature than those of original coal samples. In these coal samples, the temperatures of maximum heat emission were lowered by average $61^{\circ}C.$. Thus, it is suggested that some chemical constituents of the seawater act an important role on lowering the ignition temperature of wasted coal. By mixing seawater into wasted coals, the calorific values were increased. Especially, calorific values were greatly increased in the coal samples of lower quality as Baksan A and B with the improvement of 15~20%.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.163-165
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• 2012

Korea is now the country with shortage of electric power because of limits on power usage of businesses to prevent a possible blackout during the summer and winter. This is due to the failure to predict the total power usage. And the futhermore several accidents in the power plant during the overhaul maintenance threaten the stable power supply. Accidents were due to the combustion of low calorific coal and the shortage of the maintenance time. We should not incur a future great loss by pursuing a present small profit.

• Economic and Environmental Geology
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• v.22 no.2
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• pp.141-150
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• 1989

In order to make economic and geological evaluation of coal in Korea, proximate and ultimate analyses were carried out as well as coal petrological studies such as maceral analyses, vitrinite reflectance and sporinite fluorescence measurement. The coeffcient of correlation between each factor of both conventional utilization and coal petrological parameters were studied as in Table 5 and 6. Their conclusions were as follow: (1) for anthracite, the good parameters of coal rank are mean vitrinite reflectance, carbon content, hydrogen content and H/C atomic ratio: (2) for brown coal and sub-bituminous coal, the good parameters of coal rank are carbon content, calorific value, moisture content, hydrogen content, oxygen content and O/C atomic ratio as well as vitrinite reflectance and sporinite fluorescence. An attempt is made to infer the coalforming environment by utilization of coal petrological analyses and to make comparison of coal analyses with proximate and ultimate analyses throughout the island arc region including Japan, Philippine and Indonesia and continental region including USA, Canada and Australia. As a result, meceral composition of Paleozoic and Mesozoic anthracite are similar to that of the Paleozoic continental coals, which were formed under dry conditions or low water table, but the coalification degree suddenly increased during Daebo orogeny (middle Jurassic to lower Cretaceous). The Tertiary coal resembles those of Tertiary island arc region coal characterized by higher calorific value, volatile matter content and H/C atomic ratio and by the formation of coal under wet conditions or higher water table.

• Clean Technology
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• v.22 no.4
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• pp.299-307
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• 2016

These days, coal is one of the most important energy resources used for transportation, industry, and electricity. There are two types of coal: high-rank and low-rank. Low-rank coal has a low calorific value and contains large amounts of useless moisture. The quality of low-rank coal can be increased by simple drying technology and it needs to be stabilized by hydrocarbons (e.g. palm acid oil, PAO) to prevent spontaneous combustion and moisture re-adsorption. Spontaneous combustion becomes a major problem during coal mining, storage, and transportation. It can involve the loss of life, property, and economic value; reduce the quality of the coal; and increase greenhouse gas emissions. Besides spontaneous combustion, moisture re-adsorption also leads to a decrease in quality of the coal due to its lower heating value. In this work, PAO was used for additive to stabilize the upgraded coal. The objectives of the experiments were to determine the stabilization characteristic of coal by analyzing the behavior of upgraded coal by drying and PAO addition regarding crossing-point temperature of coal, the moisture behavior of briquette coal, and thermal decomposition behavior of coal.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.11a
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• pp.136-141
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• 2003

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.107-109
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• 2012

In Korean coal power plants, rising coal prices have recently led to the rapid utilization of low lank coals such as sub-bituminous coal with low calorific values and low ash fusion temperatures. Using these coals beyond the design range has resulted in important issues including slagging and fouling, which cause negative effects in boiler performances and unstable operations. The purpose of this study is to observe slagging and fouling characteristics resulted from burning various ranks of pulverized coals. We have tested 3 different coals: FLAME(bituminous), KCH(sub-bituminous) and MOOLARBEN(bituminous)coals in the pilot system $50kW_{th}$ scale. A stainless steel tube with preheated air inside was installed in the downstream in order to simulate water wall. Collected ash on the probe and the slag inside the furnace near burner were analyzed by SEM (scanning electron microscopy) to verify the formation degree, surface features and color changes of the pasty ash particles. Induced coupled plasma and energy dispersive X-ray spectroscopy were also performed to figure out the chemical characteristics of collected samples. As a result, KCH was observed that more slag was developed inside the walls of the furnace and on the probe than the other two kinds of coals, as shown in the calculate slagging and fouling indices as well.

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

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1374-1375
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• 2011

Mixed combustion expert system is implemented to prevent various problems in combustion process by increasing rate of mixing low calorific value coal to reduce costs. This system shows optimal coal mixture rate by interfacing CBS(Coal Blending Screener, Implementing slagging and fouling factors by coal characteristic and algorithm), SGE(Stream Generate Expert, Combustion process model) and CFS(Configured Fireside Simulator, Computational fluid dynamics).

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.209-212
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• 2012

This study was performed to analyze coal flames and measure tar and soot yields and structures of chars for two coals depending on the volatile content by the LFR(Laminar Flow Reactor) which can be applied to a variety of coal researches. The results show that volatile contents and oxygen concentration have significant influence on length and width of the soot cloud and it also indicate that the length and width of the cloud in condition of combustion decrease than those of pyrolysis atmosphere. Until the sampling height reach at 50 mm, the tar and soot yields of Berau (Sub-bituminous) coal contained relatively lots of volatile matters are less than those of Glencore A.P. (Bituminous) coal. On the other hand, tar and soot yields of Berau coal are higher than those of Glencore A.P. coal by reacted residual volatile matter. In addition, the images of samples obtained from the particle separation system of the sampling probe support for above results with the yields, and the pore development of char surface by devolatilization.

• Plant Journal
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• v.13 no.1
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• pp.44-50
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• 2017

This study calculates carbon dioxide emissions using the fuel analysis and the continuous measurement from 500 MW-class coal-fired power plants and evaluates the characteristics of each method. The emissions calculation using fuel analysis was the lowest calculation among the emissions calculation methods. This is because of low net calorific value analysis. When using the low calorific coals, it is beneficial to utilize the fuel analysis. Also it showed the characteristics of the lower calculation emissions when used the as fired coals than the as received coals. However, the difference is negligible to less than 2%. As sample analysis personnel and equipment are limited in the present circumstances, it is also deemed appropriate to use the as received coals to fuel analysis. Continuous measurement showed somewhat higher emissions than the fuel analysis, and lower emissions than calculation method using domestic emission factors. Thus, if the calculated emission using fuel analysis increases with the coal type changes, it is beneficial to using modified flow rate measurement method.