• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.323-330
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• 2019

The 500 MW Korean standard coal-fired power plant is the largest standardized power plant in Korea and has played a pivotal role in domestic power generation for over 20 years. In addition to the aging degradation due to long term operation, the probability of failure of power generation facilities is increasing due to frequent startup and stop caused by the lower utilization rate due to air pollution problem caused by coal-fired power plants. Among them, steam piping plays an important role in transferring high-temperature & pressure steam produced in a boiler to turbine for power generation. In recent years, failure of steam piping of large coal-fired power plant has frequently occurred. Therefore, in this study, failure analysis of high pressure piping weld was conducted. We identify the damage caused by high stress due to abnormal supporting structure of the piping and suggest improved supporting structure to eliminate high stress through microstructure analysis and piping stress analysis to prevent the occurrence of the similar failure of other power plant in the case of repetitive damage to the main steam piping system of the 500 MW Korean standard coal-fired power plant.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.455-460
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• 2020

In order to identify the characteristics of fine particle emissions from thermal power plants, this study conducted measurement of the primary emission concentration of TPM, PM₁₀ and PM_2.5 according to Korea standard test method (ES 01301.1) and ISO 23210 method (KS I ISO 23210). Particulate matters were sampled in total 74 units of power plants such as 59 units of coal-fired power plants, 7 units of heavy oil power plants, 2 units of biomass power plant, and 6 units of liquid natural gas power plants. The average concentration of TPM, PM₁₀, PM_2.5 by fuel are 3.33 mg/m³, 3.01 mg/m³, 2.70 mg/m³ in coal-fired plant, 3.02 mg/m³, 2.99 mg/m³, 2.93 mg/m³ in heavy oil plant, 0.114 mg/m³, 0.046 mg/m³, 0.036 mg/m³ in LNG plant, respectively. These results of TPM, PM₁₀ and PM_2.5 were satisfied with the standards of fine dust emission allowance in all units of power plants, respectively. Also, this study evaluated the characteristics of fine particle emissions by conditions of power plants including generation sources, boiler types and operation years and calculated emission factors and then evaluated fine particle emissions by sources of electricity generation.

• Plant Journal
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• v.18 no.3
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• pp.28-40
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• 2022

As the proportion of renewable energy generation is expected to increase, public power generation businesses need to actively consider implementing the expansion of biomass mixing, In this study, the biomass co-firing rate is being changed from 0wt.% to 5.0wt.% at 500MW coal-fired power plant, measuring the major operation characteristics of the pulverizer. First, the composition analysis and grinding characteristics of lignocelluosic biomass were examined, and the effect of volume increase on dirrerential bowl pressure difference, motor current, coal spillage, outlet temperature, and internal fire count was analyzed. As the co-firing rate increased, it was confirmed that the difference in the differential bowl pressure, motor current, and coal spillage treated increased, and the outlet temperature was minimal. The number of internal fires is difficult to find a clear correlation, but it has been confirmed that it is highly likely to occur in combination with other driving factors.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.596-603
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• 2007

Rapid or on-line coal analysis is of great interest in coal industry as it would allow efficient plant operation. Multivariate analysis has been applied to near-infrared(NIR) spectra coal for investigating the relationship between coal properties(%) (moisture, ash, volatile matter, fixed carbon, carbon, hydrogen, nitrogen, oxygen, sulfur), heating value(kcal/kg) and corresponding near-infrared spectral data. The quantitative analysis was carried out by applying PLS(partial least squares regression) to determine a methodology able to establish a relationship between coal properties and NIR spectral data being applied mathematical pre-treatments for minimizing the physical features of the samples. As a results of the analysis, this technique is able to classify the species of coals and to predict the all coal properties except ash, nitrogen and sulfur. The efficient operation of coal fired power plant is expected owing to real time on-line coal analysis of moisture and heating value.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.5
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• pp.552-559
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• 2008

Three dimensional numerical analysis were performed to investigate the combustion characteristics in a tangentially fired pulverized coal boiler. The predicted values at the outlet of economizer for the gas temperature, O$_2$, NO, CO were been compared with the measured data. By using the actual operating conditions of the power plant, the distribution of velocity, gas temperature, O$_2$, CO, CO$_2$ and NO as well as the particle tracking in the boiler were investigated. Throughout the present study, the non-uniform distribution of flue gas temperature in front of the final superheater might be resulted from the residual swirl flow in the upper furnace of the boiler. The present analysis on non-uniform distribution of the gas temperature could provide the useful information to prevent the frequent tube failure from happening in the final superheater of the tangentially coal-fired boiler.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.137.2-137.2
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• 2010

With current real economic growth of more than 10% per year, the Chinese energy consumption is rapidly increasing. Coal supply consists of the vast majority of China's total energy consumption requirements in 2008. China, the largest energy consumer, is expected to be heavily dependent on coal for future power generation, too (IEA,2009). A growing concern on global warming, on the other hand, drives Chinese government to declare her commitment to the reduction of CO2 emission by 2020. In this paper, China's energy market is examined for the current and future primary energy mix. Coal is found to be the biggest part accounting for 68.7% of total primary energy consumption while coal-fired power accounts for over 80% of the total power generation. The importance of Clean Coal Technology is being discussed based on the findings of the importance of coal in China's economy and its sustainable development. Among the technologies involved, a brief investigation of IGCC(Integrated Gasification Combined Cycle) technology with a review on current IGCC projects in China are provided from the perspective of environmental benefits. Studies on regional Chinese power market is also conducted. It is found that the regulated power tariff in electricity system makes the power suppliers suffer from financial loss and changes in the electricity price system is under serious consideration by Chinese government. Even though Chinese power market system causes difficulties of commercialization for IGCC technology, the potential benefits will be high due to China's huge requirements of power generating capacity and its heavy reliance on coal if the electricity price system can be changed smoothly.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.433-440
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• 2022

Environmental pollution caused by power plant exhaust gas is highlighted and eco-friendly regulations are being strengthened. However, due to the abundant reserves and low prices of coal, still the most used for power generation in the world. Therefore, flexible operation of coal-fired power plants to reduce emissions has become an inevitable option. However, lowering the output increases the possibility of acid dew point corrosion as the exhaust gas temperature decreases. The dew point corrosion occurs when condensable gases such as SO₃, HCl, NO₂ and H₂O cools below the saturation temperature. SO₃ is already well known to cause severe low- temperature corrosion in coal-fired power plants. Therefore, this study aims to prevent damage that may occur during operation by analyzing the dew point and corrosion resistance with exhaust gas temperature and sulfuric acid concentration of the power plant economizer tube.

• Journal of the Korean Society of Combustion
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• v.15 no.2
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• pp.1-11
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• 2010

Power generation systems based on the oxy-coal combustion with carbon dioxide capture and storage (CCS) capability are being proposed and discussed lately. Although a large number of lab scale studies for oxy-coal power plant have been made, studies of pilot scale or commercial scale power plant are not enough. Only a few demonstration projects for oxy-coal power plant are publicized recently. The proposed systems are evolving and various alternatives are to be comparatively evaluated. This paper presents a proposed approach for performance evaluation of a commercial 100 MWe class power plant, which is currently being considered for 'retrofitting' for the demonstration of the concept. The system is configurated based on design and operating conditions with proper assumptions. System components to be included in the discussion are listed. Evaluation criteria in terms of performance are summarized based on the system heat and mass balance and simple performance parameters, such as the fuel to power efficiency and brief introduction of the second law analysis. Also, gas composition is identified for additional analysis to impurities in the system including the purity of oxygen and unwanted gaseous components of nitrogen, argon and oxygen in air separation unit and $CO_2$ processing unit.

• Journal of Energy Engineering
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• v.19 no.2
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• pp.136-142
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• 2010

Combustion reactivity and thermal behavior of two imported coals used as a pulverized fuel of commercially thermal power plant were investigated by thermogravimetric analysis (TGA) and large scale test furnace of 200 kg/hr. TGA results showed that combustion efficiency of high moisture coal has lower than reference coal due to the slow combustion completion rate although it has the low ignition temperature, and activation energies of high moisture coal with 79 kJ/mol for overall combustion was higher than reference coal of 53 kJ/mol. Test furnace results ascertained that flame of black band of high moisture coal during the combustion in boiler broke out compared to reference coal and then it becomes to unburned carbon due to the less reactivity and combustion rate. But, Blending combustion of high moisture coal with design coal of high sulfur are available because sulfur content of high moisture coal was too low to generate the low SOx content in flue gas from boiler during the combustion. The ash analysis results show that it was not expected to be associated with slagging and fouling in pulverized coal fired systems due to the low alkali metal content of $Na_2O$ and $K_2O$ compared to bituminous coal.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.841-844
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• 2008

Non-refining fly ash and bottom ash, the byproducts generated from the coal-fired power stations, have usually been disposed of in onshore ash disposal sites. With an increase of power consumption due to industrial development, the generation of coal ash has been growing tremendously. Current insufficiency of disposal sites and environmental concerns over newly-built disposal sites have also led a growing need to utilize the coal ash. Accordingly, this paper compares and analyzes the fundamental properties of the coal ash collected from each disposal sites in order to increase the usability of the coal ash generated from coal-fired power stations. The results of the study indicate that coal ash shall be separately applied by the properties for each intended use as the ash greatly differs in its properties depending on the site of disposal. In particular, it is shown that the overall evaluation on the ash shall be necessary as the quality might be varied by the change of absorptance when applied as an aggregate for concrete. From the examination on the salt content, it has been observed that the ash can be applied as an aggregate for concrete only after more than 3 times of washing process.