Method for preventing low-dropout pipeline in shutdown process

The invention discloses a method for preventing a low-dropout pipeline in a shutdown process, belonging to the field of shutdown control in blast furnace iron-making. The method comprises the following steps: in the shutdown process of a blast furnace, controlling a stockline at 10.0-13.0m in pre-damping down; after air supply, according to the direction of the furnace top temperature, adjusting the furnace top water quantity in the direction, and controlling the unidirectional furnace top temperature in the shutdown process to be not lower than 95 DEG C; measuring the furnace top gas every 0.5h and analyzing the H2 content of the furnace top gas in the shutdown process, wherein the H2 content is within 6.0%; in a descending stockline process, controlling the furnace top temperature at 450-500 DEG C, wherein after the stockline passes an inflection point, the highest temperature is lower than or equal to 600 DEG C, and the temperature of an airtight box is lower than 60 DEG C; and in the shutdown process of the blast furnace, the dropout and air quantity are in the following relation: dropout=800.1-1.071*air quantity+0.000490*air quantity . The method disclosed by the invention can prevent a pipeline in the case of low dropout of the descending stockline so as to promote smooth operation of shutdown.