Operarional Optimization Of Auxiliary Facilities For A 1000MW Ultra Super Critical Thermal Unit

Following the applications of coordinating control system(CCS)optimization and variable frequency operation of pumps consuming huge amount of electricity,energy saving and pollution emission reduction have been achieved to a great extent.This paper focuses on the operational optimization and automatic control of auxiliary facilities with the main contributions as follows:1)Online coal weight calculation technology based pulverization system whole process controlWhole coal mill working conditions can be divided into several different phases,such as warming,starting,initial coal feeding and etc.Considering variable coal weight and feeding characteristics under different working condition,mathematical predicting models and control algorithm blocks are used to calculate real-time coal weight in the CCS for air supplying and water feeding.Based on these,mills' whole process control system is designed to keep main steam temperature and pressure from influences of recently started or stopped mills,increasing safety and stability of thermal units.2)An integration separation control strategy for the denitrification system.In the selective catalytic reduction(SCR)reactor,NOx concentration sensors are heavily influenced by purging process,which happens every couple of hours,and lasts for approximate 6-7 minutes,this leads to integral saturation in PID controller.An integration separation method is proposed to solve this problem.When purging process initializes,the sensor stops sampling data,integral part of PID is separated from control loop and maintain original value.When process of purging is over,integral part starts calculating again,and transfers to refreshed sampling value smoothly..3)Desulfurization system pH controller design for the desulfurization system considering nonlinearities of limestone slurry valveLimestone slurry control valve can be affected by agglomeration and clots,performance of pH value control system decreases.New control valve linearity testifying and correcting method is proposed to solve this problem.And a cascade control system is designed for pH value control system in order to assure pH control precision.4)A thermal unit performance online monitoring system designBased on Distributed Control System(DCS)logic blocks and user interface configuration,online performance monitoring system is developed in this paper,and used to guiding operators with real-time performance calculation.This method compensates defects of Supervisory Information System(SIS),and unit's efficiency is greatly improved...