Optimal control for fast boiler start-up based on a nonlinear model and considering the thermal stress on thick-walled components

2002 ◽  
Author(s):  
K. Kruger ◽  
M. Rode ◽  
R. Franke
Keyword(s):  
Optimal Control ◽  
Thermal Stress ◽  
Nonlinear Model ◽  
Start Up

Coordinated Control of Gas and Steam Turbines for Efficient Fast Start-Up of Combined Cycle Power Plants

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Yasuhiro Yoshida ◽  
Kazunori Yamanaka ◽  
Atsushi Yamashita ◽  
Norihiro Iyanaga ◽  
Takuya Yoshida
Keyword(s):  
Thermal Stress ◽  
Steam Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Thermal Stresses ◽  
Control Method ◽  
Coordinated Control ◽  
Combined Cycle ◽  
Steam Turbines ◽  
Start Up

In the fast start-up for combined cycle power plants (CCPP), the thermal stresses of the steam turbine rotor are generally controlled by the steam temperatures or flow rates by using gas turbines (GTs), steam turbines, and desuperheaters to avoid exceeding the thermal stress limits. However, this thermal stress sensitivity to steam temperatures and flow rates depends on the start-up sequence due to the relatively large time constants of the heat transfer response in the plant components. In this paper, a coordinated control method of gas turbines and steam turbine is proposed for thermal stress control, which takes into account the large time constants of the heat transfer response. The start-up processes are simulated in order to assess the effect of the coordinated control method. The simulation results of the plant start-ups after several different cool-down times show that the thermal stresses are stably controlled without exceeding the limits. In addition, the steam turbine start-up times are reduced by 22–28% compared with those of the cases where only steam turbine control is applied.

scholarly journals Optimal Control Strategy for SEIR with Latent Period and a Saturated Incidence Rate

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Abta Abdelhadi ◽  
Laarabi Hassan
Keyword(s):  
Optimal Control ◽  
Latent Period ◽  
Incidence Rate ◽  
Nonlinear Model ◽  
Control Strategy ◽  
Optimal Control Strategy ◽  
Vaccination Strategies ◽  
Saturated Incidence Rate ◽  
Saturated Incidence

We propose an SEIR epidemic model with latent period and a modified saturated incidence rate. This work investigates the fundamental role of the vaccination strategies to reduce the number of susceptible, exposed, and infected individuals and increase the number of recovered individuals. The existence of the optimal control of the nonlinear model is also proved. The optimality system is derived and then solved numerically using a competitive Gauss-Seidel-like implicit difference method.

Turbine Start-Up Algorithm Based on Prediction of Rotor Thermal Stress

1996 ◽  
Vol 29 (1) ◽  
pp. 6867-6872 ◽  
Author(s):  
Akimasa Nakai ◽  
Masashi Nakamoto ◽  
Atsuyuki Kakchi ◽  
Shinji Hayashi
Keyword(s):  
Thermal Stress ◽  
Start Up

scholarly journals Optimization on start-up process of high-pressure rotor for large power steam turbine

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 815-822 ◽  
Author(s):  
Qiu-Wan Du ◽  
Zhao-Li Zheng ◽  
Yong-Hui Xie
Keyword(s):  
Thermal Stress ◽  
Time Allocation ◽  
Thermal Structure ◽  
Equivalent Stress ◽  
Pattern Search ◽  
Transient Temperature ◽  
Obvious Effect ◽  
Large Power ◽  
Start Up ◽  
Maximum Equivalent Stress

This paper combines thermal-structure coupling technique and pattern search optimization algorithm to establish an optimization system for the start-up process of a turbine unit. Firstly, a finite element model for thermal-structure coupling calculation is established to accurately analyze the transient temperature field and thermal stress field, which can obtain the thermal stress distribution during start-up process. Afterwards, a program of optimization on rotor start-up process is exploited to improve the time allocation in each operating stage of start-up process, which minimizes the maximum equivalent stress of rotor. The maximum equivalent stress has reduced 25.7% after the optimization, which reveals obvious effect.

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