CONTROLLING SYSTEM FOR COMBUSTION OF COAL

PURPOSE:To increase the controllability in combustion of coal, by enabling to evaluate the coal rate at the starting time and the stopping time of coal mills, by providing a circuit to calculate the flow rate of coal from the mill, based on the feeding rate of coal into the mill at the starting time and the stopping time of the mill. CONSTITUTION:The demanded value of coal rate is put out as a signal which is calculated by adding the output from a main steam pressure controller 10 to a preceeding value (the output 8 from a function generator) based on a function processed from the flow rate of main steam. This value is compared with an output signal from a total amount of coal (an adding processor 12) by a deviation detector 13, and is processed in a propertional plus integral controller 14; and the output from the controller 14 is given to each mill as a command of coal rate. On the other hand, the coal rate correcting circuit is provided between an operator 3 and a temporary delay operator 11. When a contact point 105 for the mill in operation or a contact point 106 for the mill in a halt is turned ON at the starting time or the stopping time of the mill, an auxiliary relay 104 is energized, and the output from a coal feeder speed transmitter is to be the output of coal rate which is corrected by a changing rate limiter 101. With such an arrangement, the controllability in combustion of coal can be increased.