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

• Journal of Radiation Industry
• /
• v.10 no.4
• /
• pp.173-179
• /
• 2016

Coals and coal ashes, raw materials and by-products, in coal-fired power plants contain naturally occurring radioactive materials (NORM). They may give rise to internal exposure to workers due to inhalation of airborne particulates containing radioactive materials. It is necessary to characterize radioactivity concentrations of the materials for assessment of radiation dose to the workers. The objective of the present study was to analyze radioactivity concentrations of coals and by-products at four coal-fired plants in Korea. High purity germanium detector was employed for analysis of uranium series, thorium series, and potassium 40 in the materials. Radioactivity concentrations of $^{226}Ra$, $^{228}Ra$, and $^{40}K$ were $2{\sim}53Bq\;kg^{-1}$, $3{\sim}64Bq\;kg^{-1}$, and $14{\sim}431Bq\;kg^{-1}$ respectively in coal samples. For coal ashes, the radioactivity concentrations were $77{\sim}133Bq\;kg^{-1}$, $77{\sim}105Bq\;kg^{-1}$, and $252{\sim}372Bq\;kg^{-1}$ in fly ash samples and $54{\sim}91Bq\;kg^{-1}$, $46{\sim}83Bq\;kg^{-1}$, and $205{\sim}462Bq\;kg^{-1}$ in bottom ash samples. For flue gas desulfurization (FGD) gypsum, the radioactivity concentrations were $3{\sim}5Bq\;kg^{-1}$, $2{\sim}3Bq\;kg^{-1}$, and $22{\sim}47Bq\;kg^{-1}$. Radioactivity was enhanced in coal ash compared with coal due to combustion of organic matters in the coal. Radioactivity enhancement factors for $^{226}Ra$, $^{228}Ra$, and $^{40}K$ were 2.1~11.3, 2.0~13.1, and 1.4~7.4 for fly ash and 2.0~9.2, 2.0~10.0, 1.9~7.7 for bottom ash. The database established in this study can be used as basic data for internal dose assessment of workers at coal-fired power plants. In addition, the findings can be used as a basic data for development of safety standard and guide of Natural Radiation Safety Management Act.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.8
• /
• pp.545-552
• /
• 2010

Research and development efforts to reduce $CO_2$ emission are in progress to cope with global warming. $CO_2$ emission from fossil fuel fired power plants is a major greenhouse gas source and the post-combustion $CO_2$ capture is considered as a short or medium term option to reduce $CO_2$ emissions. In this study, the application of the post-combustion $CO_2$ capture system, which is based on chemical absorption and stripping processes, to typical fossil fuel fired power plants was investigated. A coal fired plant and a natural gas fired combined cycle plant were selected. Performance of the MEA-based $CO_2$ capture system combined with power plants was analyzed and overall plant performance including the energy consumption of the $CO_2$ capture process was investigated.

• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.2
• /
• pp.83-92
• /
• 2019

Spontaneous combustion propensity of various coals of carbonization grade as a pulverized fuel of coal-fired power plant has been tested from an initial temperature of $25^{\circ}C$ to $600^{\circ}C$ by heating in an oven with air to analyze the self-oxidation starting temperature. These tests produce CPT (Cross Point Temperature), IT (Ignition temperature), and CPS (Cross Point Slope) calculated as the slope of time taken for a rapid exothermic oxidation reaction at CPT base. CPS shows a carbonization rank dependence whereby wood pellet has the highest propensity to spontaneous combustion of $20.995^{\circ}C/min$. A sub-bituminous KIDECO coal shows a CPS value of $15.370^{\circ}C/min$, whereas pet coke has the highest carbonization rank at $2.950^{\circ}C/min$. The nature of this trend is most likely attributable to a concentration of volatile matter and oxygen functional groups of coal surface that governs the available component for oxidation, as well as surface area of fuel char, and constant pressure molar heat.

• Journal of Environmental Health Sciences
• /
• v.36 no.2
• /
• pp.128-135
• /
• 2010

The main purpose of this study was to develop the greenhouse gas emission factor for power plant using sub-bituminous coal. In Korea, Fired power plant are a major source of greenhouse gases within the fossil fuel combustion sectors, thus the development of emission factors is necessary to understand the characteristics of the national specific greenhouse gas emission and to develop nation specific emission factors. These emission factors were derived from the $CO_2$ concentrations measurement from stack and fuel analysis of sub-bituminous coal. Caloric value of sub-bituminous coal used in the power plants were 5,264 (as received basis), 5,936 (air-dried basis) and 6,575 kcal/kg (dry basis). The C emission factors by fuel analysis and $CO_2$ concentration measurement was estimated to be 26.7(${\pm}0.9$), 26.3(${\pm}2.8$)tC/MJ, respectively. Our estimates of C emission factors were comparable with IPCC default value.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.3
• /
• pp.157-166
• /
• 2009

The pulverized coal combustion behavior in the coal fired utility boiler has been investigated with the CFD and process analysis techniques. The used commercial software were CFX and PROATES, and these were coupled each other to get more reliable boundary condition set-up, resulting in more reliable solution. For two cases which were the actual operation condition of A power plant, the calculated values from the coupled CFD and process analysis for thermal energy system were compared with the plant data, and the good agreements were obtained for Case 1 and 2. The calculated temperature distributions on the surface of heat exchangers were compared with the plant data for the steam temperatures across heat exchangers, and these explained the actual operating situation very well. The temperature deviation across the final superheater tube, which was believed to be the main cause of the frequent tube failure, were also explained very well with the calculated distributions of gas temperature and radiation on the plane of the final superheater.

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

• Plant Journal
• /
• v.10 no.3
• /
• pp.34-38
• /
• 2014

Coal-fired power plants have used oil as fuel for start-up but plasma burner is recently introduced in order to reduce costs. It provides fuel oil-free start-up. But at initial operation of Plasma burner, an increase in unburned carbon remains as still pending issue. Also research and operational standards for this problem are insufficient. In this paper, operating procedure will be proposed through analyzing the impact of unburned carbon in accordance with the Plasma arc current. It is also possible to contribute to the national plant industry by demonstrating economics of Plasma burner in commissioning coal-fired power plants.

• Journal of Environmental Science International
• /
• v.14 no.8
• /
• pp.761-770
• /
• 2005

Scanning electron microscopy / energy dispersive X-ray analyzer(SEM/EDX) has played an important role for evaluation the source of atmospheric particle because it is a powerful tool for characterizing individual particles. The SEM/EDX system provides various physical parameters like optical diameter, as well as chemical information for a particle-by-particle basis. The purpose of the study was to classify individual particle emitted from the point sources based on clustering analysis and physico-chemical analysis by SEM/EDX. The total of 490 individual particle were analyzed at 8 point sources including coal-fired power plant, incinerator, H-C oil boiler, and metal manufacturing industry. The main components were Si and AI in the coal-fired power plant, Cl and Na in the domestic waste Incinerator, S in the H-C oil boiler and S and Fe in the metal manufactory industry, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.10
• /
• pp.67-72
• /
• 2010

G8 summit meeting held in July 2008 decided to set up a long-term goal, by 2050, reducing the world greenhouse emissions by half of those emitted in 1990. In November 2009, the Government announced to reduce the national $CO_2$ emission by 30[%] of BAU by 2020. Electric power industries in Korea produce most of their electricity by burning fossil fuels, and emit approximately 28[%] of national $CO_2$ emissions. Monitoring the $CO_2$ emissions. Monitoring the $CO_2$ emission of electric power plants is very important. This paper presents a method to calculate the hourly $CO_2$ emission for a thermal power plant burning mixture of coal and oil using the performance test data and coal-oil mix rate. An example of $CO_2$ emission calculation is also demonstrated.