Layered calorific value modification method for multi-coal blended burning unit

The invention relates to a layered calorific value modification method for a multi-coal blended burning unit. Through a 'layered rough setting + automatic fine adjusting' calorific value modification mode, the method comprises the following steps: (1) respectively setting the calorific values of all coal beds, and calculating the average calorific value after layered setting to obtain an average calorific value modification coefficient K1 after layered rough setting; (2) obtaining a calorific value modification coefficient K2 through an automatic calorific value modification loop; and (3) obtaining a final calorific value modification coefficient K through the formula (K=K1*K2) and outputting the final calorific value modification coefficient K to a control system for modification control. Compared with the prior art, the layered calorific value modification method realize quick and effective calorific value modification when the unit is under the multi-coal burning working condition, so that the operation safety and economy of the unit under the condition of changeable coals are improved.