DTF내 미분탄의 탈휘발 거동 해석 및 실험 장지훈(Jihoon Jang); 한가람(Karam Han); 유근실(Geun Sil Yu) ...
한국연소학회지,
06/2019, Letnik:
24, Številka:
2
Journal Article
Recenzirano
Devolatilization behavior of pulverized coal in a drop tube furnace (DTF) has been calculated with the measured gas temperature and velocity. The particle temperature and velocity were calculated ...from the energy and momentum equations of particle by using the fourth order Runge-Kutta method. The volatile evolved from the particle along with the reactor tube was also calculated varying the wall temperature of reaction tube as well as the particle diameter. The optimal kinetic parameters of subbituminous coal were obtained from the volatile evolution data of the devolatilization experiment in the DTF by error minimization. KCI Citation Count: 2
A power transformer is one of the main components in a power plant and transformer failure may provoke power plant shut-down with significant capital loss. Many techniques of vibration-based health ...diagnostics have been developed in order to prevent mechanical failures of the transformer. Vibration-based health diagnostics results are generally sensitive to the number of sensors and their locations. This study aims at developing robust health diagnostics for two dominant mechanical failure mechanisms of the transformer. Based upon the characteristics of transformer vibration, robust health indices were developed using sensitivity analysis. This study employed 33 transformers and each with 36~48 accelerometers for demonstration purpose. It is concluded that the proposed health index are suitable for robust health diagnostics and fault identification of power transformers.
This paper describes an optimal design of a notch filter for the active magnetic bearing (AMB) system which has unstable poles. A Notch filter is designed as 2 nd order standard transfer function ...with two zeros and two poles. We performed optimization to design a notch filter using sequential quadratic programming (SQP) and evaluate the closed loop stability with a designed notch filter. The designed notch filter is optimized to have the lowest peak sensitivity with respect to the disturbance closed loop system. The designed notch filter is examined for the compensation effect for the unstable 2 nd order system. We applied the design optimization to large scale flywheel energy storage system (FESS). FESS can store up to 5kWh of usable energy at the maximum speed of 18,000 rpm. The effect of the designed filter from optimization is simulated using simulation model of FESS and the simulation model is validated against experiments.
This paper describes a comparison of stability of two large-capacity flywheel energy storage systems (FESSs) supported by active magnetic bearings. We designed and manufactured two systems that can ...store up to 5 kWh of usable energy at the maximum speed of 18,000 rpm. One of them is optimized to store as much energy per weight as possible, resulting in a flywheel with a strong gyroscopic coupling. The other design has a much smaller gyroscopic coupling for the ease of control. In order to analyze the stability of the systems accurately, we derived dynamic models of the flywheel rotor using finite-element method, and reduced-order models using modal truncation. The rotor model is combined with those of active magnetic bearings, amplifiers, and position sensors, resulting in a system simulation model. This simulation model is validated using experimental measurements. The stability of the system is checked from the pole locations of the closed-loop transfer functions. We also investigated the sensitivity function to quantify the robustness of the systems to the disturbances such as mass unbalance and sensor noises.
The combined cycle plant is an integration of gas turbine and steam turbine, combining the advantages of both cycles. It recovers the heat energy from gas turbine exhaust to use it to generate steam. ...The heat recovery steam generator plays a crucial role in combined cycle plants, providing the link between the gas turbine and the steam turbine. Simulation of the performance of the HRSG is required to study its effect on the entire cycle and system. Computational fluid dynamics has potential to become a useful to validate the performance of the HRSG. In this study a solver has been implemented in the open source code, OpenFOAM, for combustion simulation in the heat recovery steam generator. The solver is based on the steady laminar flamelet model to simulate detailed chemical reaction mechanism. Thereafter, the solver is used for simulation of HRSG system. Three cases with varying fuel injections and gas turbine exhaust gas flow rates were simulated and the results were compared with measurements at the system outlet. Predicted temperature and emissions and those from measurements showed the same trend and in quantitative agreement.
배열형 음향센서를 이용한 발전설비 소음원 탐지시스템 개발 손석만; 김동환; 이욱륜 ...
KEPCO Journal on electric power and energy,
2015, Letnik:
1, Številka:
1
Journal Article
Odprti dostop
In this study, it has been initiated to investigate the specific abnormal vibration signal that has been captured in the power equipment. Array Microphone can be used in order to detect the direction ...and the position of the noise source. It is possible to track the abnormal mechanical noise in the power plant by utilizing the program and the microphone array system developed from this research. Array microphone system can be operated as a constant monitoring system.
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