Goyang, South Korea
Goyang, South Korea

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Yu J.,Pusan National University | Yoo J.,XEONET Co. | Jang J.,Korea East - West Power Co, Ltd. | Park J.H.,Pusan National University | Kim S.,Pusan National University
Energy | Year: 2017

During startup or normal operations, tube monitoring systems for steam boilers can considerably improve efficiency and reliability in thermal power plants (TPPs). Although several attempts have been made to detect and locate boiler tube leaks, what seems to be lacking is the study for tube plugging, one of the fundamental causes of the leaks and other tube failures. Scale and deposit formations on inner surfaces of tubes cause the tubes to be plugged. Although the formations can be suppressed and removed by chemical treatments for boiler water and steam blowing during startup procedures, it is still difficult to monitor and prevent tube plugging during startup or normal operations. In this paper, a novel plugged tube detection and identification approach is proposed for final super heater (FSH) tube banks. Principal component analysis is applied to tube temperature data for plugging detection and identification. The data are collected from thermocouples installed on the FSH outlet header section. To identify plugged tubes, contribution analysis and the characteristics of plugged tube temperatures are employed. To verify the performance of the proposed method, tube temperature data from an 870 MW supercritical coal-fired TPP are used. The experiment results show that the proposed method can successfully detect and identify plugged tubes. The proposed method can help to decide how many times steam blowing should be performed, whether startup procedures should be delayed or stopped, and which tubes should be maintained. Furthermore, severe tube failures can be prevented by avoiding damage from overheating due to tube plugging. © 2017 The Authors

Lee S.-H.,Korea University | Yoon K.-B.,Chung - Ang University | Choe B.-H.,Korea University | Min D.-S.,Korea University | And 3 more authors.
Journal of Korean Institute of Metals and Materials | Year: 2010

The creep crack growth rate (da/dt) of the Cr-Mo steels tested by pre-crack and the voltage (or resistance) variables were related into fracture parameter (Ct), crack growth coefficient (H), and an exponent (q) in the parts of Base, weld and HAZ. The fracture parameter (Ct) has various variables relating to the specimen and crack shape, applied stress, and creep strain curve. The H and q was inferred by OLS regression (ordinary least square method), and the H values were solved in statistics and probability assessment, which were attained fromPDF's distributions (probability density function). The HAZ part has the highest value of q by OLS regression and the widest distribution of H by PDF of WEIBULL, which means that the crack sensitivity of HAZ should be cautioned against the creep crack growth and failure.

Ryu J.-S.,Korea East - West Power Co, Ltd. | Kim K.-S.,Inha University | Park S.-J.,Inha University
Applied Chemistry for Engineering | Year: 2011

In this work, various wood biomasses were used to determine the combustion characteristics for the fuel of cogeneration plant. Combustion characteristics of four types, i.e., (i) forest products, (ii) recycled wood, (iii) empty fruit bunch, and (iv) palm kernel shell, were examined via thermal gravimetric analyzer (TGA) in air atmosphere and coal was used as a comparison group. From the TGA results, the combustion of the wood biomass was occurred in the range of 280 to 420 °C, which was lower than that of coal. Forest product showed the lowest activation energy (0.4 kJ/mol) compared to that of other wood biomasses (about 6 to 14 kJ/mol) and coal (64 kJ/mol). In addition, the reaction rate constant of the wood biomass was lower than that of coal. These results indicate the higher combustion initiation rate of wood biomass due to the high content of volatile matter, which had a low boiling point.

Lee J.H.,KEPCO E&C | Lee D.W.,KEPCO E&C | Gyu J.S.,KEPCO E&C | Kwak N.-S.,KEPCO E&C | And 4 more authors.
Korean Chemical Engineering Research | Year: 2015

Estimating potential of CO2 emission reduction of non-capture CO2 utilization (NCCU) technology was evaluated. NCCU is sodium bicarbonate production technology through the carbonation reaction of CO2 contained in the flue gas. For the estimating the CO2 emission reduction, process simulation using process simulator (PRO/II) based on a chemical plant which could handle CO2 of 100 tons per day was performed, Also for the estimation of the indirect CO2 reduction, the solvay process which is a conventional technology for the production of sodium carbonate/sodium bicarbonate, was studied. The results of the analysis showed that in case of the solvay process, overall CO2 emission was estimated as 48,862 ton per year based on the energy consumption for the production of NaHCO3 (7.4 GJ/tNaHCO3). While for the NCCU technology, the direct CO2 reduction through the CO2 carbonation was estimated as 36,500 ton per year and the indirect CO2 reduction through the lower energy consumption was 46,885 ton per year which lead to 83,385 ton per year in total. From these results, it could be concluded that sodium bicarbonate production technology through the carbonation reaction of CO2 contained in the flue was energy efficient and could be one of the promising technology for the low CO2 emission technology.

Ryu J.-S.,Korea East - West Power Co, Ltd. | Kim K.-S.,Inha University | Park S.-J.,Inha University
Journal of Industrial and Engineering Chemistry | Year: 2012

Polystyrene (PS)/wood chip (WC) composites (PS/WC) were prepared by solution mixing method and the effect of polystyrene on thermal characteristics of WC was investigated with different PS/WC ratios. The copyrolysis and heating value of the PS/WC were determined by thermogravimetric analyzer and calorimeter, respectively. From the results, the PS/WC revealed copyrolysis features in the range of 360-440. °C compared to WC and PS and exhibited high heating value over about 5000. kcal/kg at low PS content (PS/WC = 2/8). These results were attributed to the combination effect by interaction between polystyrene and wood chip. © 2012 The Korean Society of Industrial and Engineering Chemistry.

Choi S.M.,University of Seoul | Lee W.S.,T sec Structural Engineering | Oh K.J.,Hee Sang Reinforce | Lee S.W.,Korea East - West Power Co, Ltd. | Moon J.Y.,University of Seoul
Proceedings of the 13th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2013 | Year: 2013

Braces controlling tension have been used to resist lateral force in most of medium and row-rise steel structures. Providing high stiffness and strength, these steel brace frames are effective to resist lateral force and control story drift. However, the steel braces are subject to compressive load, they experience the deterioration in load capacity due to bending buckling before yield stress and ideal energy dissipation is unfeasible, which causes unstable behavior of the structure. Therefore, this study has to do with a reinforcing method of the compression brace proposed as friction bolt connection. In order to verify the compressive behavior of the reinforced braces, structural performance test was conducted with variables of slenderness ratio and the amount of reinforcement.

Lee J.H.,KEPCO E&C | Lee D.W.,KEPCO E&C | Gyu J.S.,KEPCO E&C | Kwak N.-S.,KEPCO E&C | And 4 more authors.
Korean Chemical Engineering Research | Year: 2014

Economic evaluation of the manufacturing technology of high-value chemicals through the carbonation reaction of carbon dioxide contained in the flue gas was performed, and analysis of the IRR (Internal Rate of Return) and whole profit along the production plan of the final product was conducted. Through a carbonation reaction with sodium hydroxide that is generated from electrolysis and by using carbon dioxide in the combustion gas that is generated in the power plant, it is possible to get a high value products such as sodium bicarbonate compound and also to reduce the carbon dioxide emission simultaneously. The IRR (Internal Rate of Return) and NPV (Net Present Value) methods were used for the economic evaluation of the process which could handle carbon dioxide of 100 tons per day in the period of the 20 years of plant operation. The results of economic evaluation showed that the IRR of baseline case of technology was 67.2% and the profit that obtained during the whole operation period (20 years) was 346,922 million won based on NPV value. When considering ETS due to the emissions trading enforcement that will be activated in 2015, the NPV was improved to a 6,000 million won. Based on this results, it could be concluded that this CO2 carbonation technology is an cost-effective technology option for the reduction of greenhouse gas.

Yu J.,Pusan National University | Jang J.,Korea East - West Power Co, Ltd. | Yoo J.,XEONET Co. | Park J.H.,Pusan National University | Kim S.,Pusan National University
Journal of Electrical Engineering and Technology | Year: 2016

System failures in thermal power plants (TPPs) can lead to serious losses because the equipment is operated under very high pressure and temperature. Therefore, it is indispensable for alarm systems to inform field workers in advance of any abnormal operating conditions in the equipment. In this paper, we propose a clustering-based fault detection method for steam boiler tubes in TPPs. For data clustering, k-means algorithm is employed and the number of clusters are systematically determined by slope statistic. In the clustering-based method, it is assumed that normal data samples are close to the centers of clusters and those of abnormal are far from the centers. After partitioning training samples collected from normal target systems, fault scores (FSs) are assigned to unseen samples according to the distances between the samples and their closest cluster centroids. Alarm signals are generated if the FSs exceed predefined threshold values. The validity of exponentially weighted moving average to reduce false alarms is also investigated. To verify the performance, the proposed method is applied to failure cases due to boiler tube leakage. The experiment results show that the proposed method can detect the abnormal conditions of the target system successfully. © The Korean Institute of Electrical Engineers.

Korea Electric Power Corporation and Korea East - West Power Co, Ltd. | Date: 2013-07-17

There is provided a pipeline inspection device including: a body part contacting a pipeline and accommodating the pipeline; a coupling part coupled to the body part to enclose the pipeline; and a sensor part including a sensor on at least one of one side of the body part and one side of the coupling part which are in contact with the pipeline to inspect an internal state of the pipeline. The pipeline inspection device according to exemplary embodiments is capable of inspecting pipelines without increasing a gap between the pipelines even in a case in which the gap therebetween is relatively narrow, and is capable of readily and rapidly inspecting a large area of pipelines.

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