ANALYSIS OF FAULTS IN OPERATION OF MPS TYPE MEDIUM SPEED COAL PULVERISERS AND RETROFIT OF ITS CONTROL FUNCTIONS

On the basis of analysing the operating condition and fault phenomena of MPS type medium speed coal pulverizers equipped for unit no.3 in Huaneng Jinggangshan Power Plant and unit no.5 in Huaneng Fuzhou Power Plant,the loading control function of original coal pulverizers has been retrofitted,the functions,such as logic for tripping the coal pulverizer due to the rollers being unlifted up,and automatic reduction of the set value for reactive oil pressure in case of lowering the rollers for loading the coal pulverizer etc.being added.After refrofit,the control logic can realize automatic adjustment of the rollers,and regulation of the loading curves,as well as the closed-loop astatic regulation of the oil pressure etc..Results of operation show that the control logic after retrofit overcomes the defects of the original control logic,such as single function and frequent setting etc.,prevuenting effectively the vibration of coal pulverizer and coal plugging in the coal pulverizer due to the pulverizing ability is unmatch with the coal quantity and the coal quality.