Novel coordinated control method with coal-quality correction of circulating field bed boiler
To improve the load-following capability and the coal-quality applicability of a circulating field bed boiler (CFBB), a new coordinated control method with coal-quality correction is proposed in this paper. This method takes the primary air as another new control variable into the coordinated control of CFBB, which can take advantage of the unburned carbon in bed to improve its load-following capability. Simultaneously, a multivariable predictive controller based on augmented state space model is designed to deal with the CFBB's characteristics such as time-delay and strong coupling. Finally, an improved strategy to correct coal-quality online based on the disturbance observer is provided. Compared with the conventional control scheme, the simulation results for a 330MW CFBB shows that the method proposed in this paper can significantly improve the load-following capability and the coal-quality applicability.
Coordinated Control in 135MW CFB Boiler
CFB(Circulating Field Bed) is an advanced coal-burning technology which has grown rapidly in recent years,because of its high efficiency,low pollution,fuel flexibility and good performance in load control.It has been widely used in most of power plant boilers from 12MW rubbish incineration to Sichuan Baima 600MW supercritical pressure circulating fluidized bed(SCCFB) power plant under construction.For realization of units Automatic Generation Control(AGC),coordinated control system(CCS) has been widely used in CFB generation units.All units with capacity more than 135MW has adopted coordinated control system.However,due to the characteristics of long time-delayed,strongly coupled and nonlinear time-varying,as well as current control system is based on linearization or identification model,so when there is suddenly changes of coal type,it will cause significant fluctuations to unit load and steam pressure,leading to not ideal result of failure coordinated control.Based on this situation,some proposal for CCS optimization to 135MW XX power plant is presented.Adding predictions of changes of coal type in control scheme,with combination of ideal model and prediction model,coordinated control to turbine and boiler will obtain better effect.
The Application of Intelligent Control to Combustion Control System of CFB Boiler
The combustion in circulated fluidized-bed (CFB) boiler is a complex and multi-variables coupling process. It is too difficult to build an exact mathematic model to describe the process. The main stream pressure control is an important subsystem of burning system, and it is difficult for the norm PID algorithm to control it. According to these, the human-simulated intelligent control technique is applied to the main steam pressure. It compensates the disadvantages of traditional control method and had perfect advantages in economy and in reality. The control rules of the controller can be modified, compensated and perfect in the practical operation. The practice shows that this controller has strong self-adaptability.