The Study Of The Medium-speed Pulverizer's Intelligent Control And Air Distribution Influence On The Boiler's Economical Operation

Coal resource is abundant in our country, so thermal power generation accounts for more than 80 percent of the country's total generating capacity.As the improving of technology and the requirements of energy saving and emission reduction, there are emerged increasing contradictions between electricity and coal, so the development of large-capacity and high-parameter ultra-supercritical (USC) unit has become the main trend. Both the number of having already run and being under construction of the USC, our country occupies the world leader. On the one hand the efficiency of the USC is higher and the effect of the environmental protection is better, on the other hand the high parameter has brought the difficulty for unit's coordination control. How to control the units quickly and accurately becomes the primary problem for the researchers.First, as the main auxiliary engine of the power unit -pulverizer, this article analyzes all kinds of pulverizers, and then the mathematical model of the MPS pulverizer is established according to its workings. The main parameters, such as the output of pulverizer, the differential pressure between import and export and the outlet temperature are calculated by this model. we study the influence of the pulverizer's output and outlet temperature with the changing the amount of the coal by simulink.Second, according to statistics, more than 80 percent of loss of the boiler is due to the air distribution. The heat loss due to exhaust gas and unburned carbon are the main parts of the boiler's loss.How to match the wind reasonably is not only on direct effects to the combustion and exhaust gas temperature, but also a key factor to reduce the heat loss due to exhaust gas and unburned carbon. Therefore distributing the wind reasonably can make combustion optimization, reduce heat loss and improve the boiler's efficiency. Because theBP neural network can describe the complicated and nonlinear systems easily, the BP neural network for air system with the six inputs and three outputs is established for fitting the function of the inputs and outputs in this paper. This BP neural network can predict the temperature of exhaust gas and the efficiency of boiler accurately. The best combination of boiler Load, the pressure of primary and secondary air, the speed of coal feeder and so on are determined by this function which can ensure the combustion completely. On the basis of the existing operation parameters, opening degree of the primary and secondary air values are recorded for the operator to adjust each air throttle's opening with the the change of boiler load timely and accurately. So it can meet the requirement of pulverizer and the boiler and improve security and economy of the milling system and combustion system.Basing on the conventional control strategy of the pulverizer, an improved control strategy with differential pressure control is introduced in this paper.Finally, there are two methods that can calculate the effciency of the boiler: AMSE standard and national standard.Then a new simplified method is presented on the base of national standard.This process is programmed with the purpose of caiculating the efficiency more conveniently and quickly in the permissible error of the engineering. It is of some value to the safety and stability of the unit.