A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is ba...A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.展开更多
This paper proposed a simple approach to determine noise frequency of boiler drum level in order to improve control performance. Based on analysis of uncertainty of drum level, the redundant oscillation component of s...This paper proposed a simple approach to determine noise frequency of boiler drum level in order to improve control performance. Based on analysis of uncertainty of drum level, the redundant oscillation component of signal, noise is ascribed to the surface wave of drum water. According to the characteristic of surface wave, a new method was proposed to determine noise’s frequency band. By gradually removing the lowest frequency component of signal, the variance of remained component is calculated and observed. An apparent turning point was found and the corresponding critical frequcncy was determined. With this result a low-pass filter was designed to separate noise component. Finally validation is conducted by comparing the proposed method and conventional ones. Results show the accuracy and simpleness of the proposed method.展开更多
A boiler drum BDT921 that is installed in the Control Laboratory, Department of Mechatronics and Robotics Engineering, Faculty of Electric and Electronic Engineering, Universiti Tun Hussein Onn Malaysia （UTHM） is be...A boiler drum BDT921 that is installed in the Control Laboratory, Department of Mechatronics and Robotics Engineering, Faculty of Electric and Electronic Engineering, Universiti Tun Hussein Onn Malaysia （UTHM） is being used as a model plant to achieve the digital control system since its analog. Implementing a digital system to boiler quite a though work. This paper covers analysis from the experiment done to match with digital design that will be implemented to the real system. The digital control design will come up with the mathematical model and will be analyzed with MATLAB and SIMULINK software named as ＂Discrete Analysis ofBDT921 Simulation＂. A proportional integral and derivative （PID） controller is being chosen as the control element in discrete form as the real system is using the same control element. The output responses behave as the second order system with a bit difference in rise times and peak times compared with data obtained from experiment. With regarding to the analysis done, the digital control can be implemented and for further viewing, to be controlled digitally with computer in the control room.展开更多
Numerical simulation of complex systems and components by computers is a fundamental phase of any modern engineering activity. The traditional methods of simulation typically entail long, iterative processes which lea...Numerical simulation of complex systems and components by computers is a fundamental phase of any modern engineering activity. The traditional methods of simulation typically entail long, iterative processes which lead to large simulation times, often exceeding transient real time. Artificial neural networks （ANNs） may be advantageous in this context, the main advantage being the speed of computation, the capability of generalizing from the few examples, robustness to noisy and partially incomplete data and the capability of performing empirical input-output mapping without complete knowledge of underlying physics. In this paper, the simulation of steam generator is considered as an example to show the potentialities of this tool. The data required for training and testing the ANN is taken from the steam generator at Abott Power Plant, Champaign （USA）. The total number of samples is 9600 which are taken at a sampling time of three seconds. The performance of boiler （drum pressure, steam flow rate） has been verified and tested using ANN, under the changes in fuel flow rate, air flow rate and load disturbance. Using ANN, input-output mapping is done and it is observed that ANN allows a good reproduction of non-linear behaviors of inputs and outputs.展开更多
In order to develop a feasible model of drum level sloshing, the mechanism of drum level sloshing was analyzed, and the model of drum level sloshing was developed on the Easy5 software flat. The thermodynamic property...In order to develop a feasible model of drum level sloshing, the mechanism of drum level sloshing was analyzed, and the model of drum level sloshing was developed on the Easy5 software flat. The thermodynamic property of the model was validated by using the reference model, which was set up by using the method of lump parameter. The results indicate that the model can precisely reflect the phenomena of thermodynamic property inside drum, and the numeric error is within 1%. And the hydraulic property of the model was validated by the analytical theory of liquid sloshing, and the results indicate that the hydraulic property inside drum can also be correctly reflected by the model, and the sloshing period error is within 5%. The important work was done for exploring modeling for drum level sloshing, research of drum level sloshing and precision controlling of drum level.展开更多
基金Funded by the National Science and Technology Support Project of China (No. 2006BAA03B02-03)
文摘A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermaUy insulated. Combining this model with the control-volume method provides temperatures at different points on a cross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonstrated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.
文摘This paper proposed a simple approach to determine noise frequency of boiler drum level in order to improve control performance. Based on analysis of uncertainty of drum level, the redundant oscillation component of signal, noise is ascribed to the surface wave of drum water. According to the characteristic of surface wave, a new method was proposed to determine noise’s frequency band. By gradually removing the lowest frequency component of signal, the variance of remained component is calculated and observed. An apparent turning point was found and the corresponding critical frequcncy was determined. With this result a low-pass filter was designed to separate noise component. Finally validation is conducted by comparing the proposed method and conventional ones. Results show the accuracy and simpleness of the proposed method.
文摘A boiler drum BDT921 that is installed in the Control Laboratory, Department of Mechatronics and Robotics Engineering, Faculty of Electric and Electronic Engineering, Universiti Tun Hussein Onn Malaysia （UTHM） is being used as a model plant to achieve the digital control system since its analog. Implementing a digital system to boiler quite a though work. This paper covers analysis from the experiment done to match with digital design that will be implemented to the real system. The digital control design will come up with the mathematical model and will be analyzed with MATLAB and SIMULINK software named as ＂Discrete Analysis ofBDT921 Simulation＂. A proportional integral and derivative （PID） controller is being chosen as the control element in discrete form as the real system is using the same control element. The output responses behave as the second order system with a bit difference in rise times and peak times compared with data obtained from experiment. With regarding to the analysis done, the digital control can be implemented and for further viewing, to be controlled digitally with computer in the control room.
文摘Numerical simulation of complex systems and components by computers is a fundamental phase of any modern engineering activity. The traditional methods of simulation typically entail long, iterative processes which lead to large simulation times, often exceeding transient real time. Artificial neural networks （ANNs） may be advantageous in this context, the main advantage being the speed of computation, the capability of generalizing from the few examples, robustness to noisy and partially incomplete data and the capability of performing empirical input-output mapping without complete knowledge of underlying physics. In this paper, the simulation of steam generator is considered as an example to show the potentialities of this tool. The data required for training and testing the ANN is taken from the steam generator at Abott Power Plant, Champaign （USA）. The total number of samples is 9600 which are taken at a sampling time of three seconds. The performance of boiler （drum pressure, steam flow rate） has been verified and tested using ANN, under the changes in fuel flow rate, air flow rate and load disturbance. Using ANN, input-output mapping is done and it is observed that ANN allows a good reproduction of non-linear behaviors of inputs and outputs.
基金The National Natural Science Foundation of China ( No. 5997022 )Edison Research Foundation from some famous American company (No.200310)
文摘In order to develop a feasible model of drum level sloshing, the mechanism of drum level sloshing was analyzed, and the model of drum level sloshing was developed on the Easy5 software flat. The thermodynamic property of the model was validated by using the reference model, which was set up by using the method of lump parameter. The results indicate that the model can precisely reflect the phenomena of thermodynamic property inside drum, and the numeric error is within 1%. And the hydraulic property of the model was validated by the analytical theory of liquid sloshing, and the results indicate that the hydraulic property inside drum can also be correctly reflected by the model, and the sloshing period error is within 5%. The important work was done for exploring modeling for drum level sloshing, research of drum level sloshing and precision controlling of drum level.
