Improved coal grinding and fuel flow control in thermal power plants

Abstract

A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated in the mill by employing a special variant of a Luenberger observer. The controller uses the rotating classifier to improve the dynamical performance of the overall system. The proposed controller is compared with a PID-type controller with available pulverized coal flow measurements under nominal conditions as well as when parameter uncertainties and noise are present. The proposed controller lowers the grinding power consumption while in most cases exhibiting superior performance in comparison with the PID controller.

Review of control and fault diagnosis methods applied to coal mills

“…A substantial reduction in the power consumption and superior performance compared to the PID control is achieved by P. Niemczyk and J. D. Bendtsen [71] after designing a controller for coal grinding and pulverized fuel flow control based on the optimal control theory for bilinear systems with integral action. Angular velocity of the classifier is used as the control variable.…”

“…Methods like MPC [66][67][68][69][70][71][72][73][74][75][76][77] are able to achieve tight control with less overshoot for the mill system. The strength of using MPC is that the constraints on the input and output variables can be handled easily and the large time delay encountered in the milling system can be taken care of by the feed forward design of MPC, but these methods need accurate mathematical models for mills.…”

“…Hence, the control performance is highly influenced by the accuracy of the model. The MPC approach developed for mill control [66][67][68][69][70][71][72][73][74][75][76][77] should be checked under different and varying operating conditions of the mill.…”

A Review on Novel Approach towards the Methods for Detection of Growth Parameters in Plants

“…The sample preparation included that plant sample cuttings transferred to a normal water tank with six to ten small chambers. Hoagland nutrient provided and proper nitrogen and phosphorus concentrations regulated [12]. Then root cuttings cultivated in a greenhouse under a photoperiod of 16h temperature at 25 °C/20 °C in day/night [13] .…”