| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently increase the transportation efficiency of discharged mud by forming a plug and prevent blocking of a pipe for discharged mud in advance by catching an omen thereof. SOLUTION: A valve for discharged mud 16 and a valve for introducing air 20 are alternately opened, closed, and controlled based on predetermined conditions to carry out discharged mud in a discharged mud tank 12 in a plug shape. Moreover, the presence of an omen of blocking is judged based on outputs of a hold up sensor 40, and when it is judged that there is an omen of blocking, the opening and closing control is temporarily stopped to close the valve for discharged mud 16 and open the valve for introducing air 20, and when the omen of blocking disappears, the operation is returned to the opening and closing control. |
