Method for discharging granular powder brought into fixed state inside hollow structure
A rack rail is suspended into a silo from an opening formed in a ceiling portion of the silo and a lifting body is lowered into the silo along the rack rail from the opening. A work scaffold is built on the lifting body using a part carried into the silo from the opening, a worker connected to the work scaffold with a safety belt pokes and breaks down a granular powder in a state where a discharge port of a silo bottom portion is closed, the poked and broken down granular powder drops to a rat hole (or boring hole), the worker connected to the work scaffold with the safety belt adds a rack rail in a state where the rat hole is blocked with the granular powder, the discharge port is opened to discharge the granular powder stored in the passage, and then the work scaffold is lowered to the added rack rail.
1. A method for, when a granular powder stored inside a hollow structure is brought into a fixed state and cannot be discharged from a discharge port of a bottom portion of the hollow structure, breaking down the granular powder in the fixed state, and then discharging the granular powder from the discharge port, the method comprising
the steps of:
suspending a rack rail of a predetermined length into an upper space in the hollow structure from an opening formed in a ceiling portion of the hollow structure;
lowering a lifting body moving along the rack rail from the opening to the upper space in the hollow structure along the rack rail;
building a work scaffold so as to project in a horizontal direction on the lifting body in the upper space in the hollow structure using a part carried into the hollow structure from the opening;
poking and breaking down the granular powder in the fixed state under the work scaffold by a worker connected to the work scaffold with a safety belt in a state where the discharge port of the bottom portion of the hollow structure is closed:
dropping the poked and broken down granular powder to a passage formed in the granular powder in the fixed state under the work scaffold from a top surface of the granular powder to the discharge port in the closed state of the bottom portion of the hollow structure;
adding a next rack rail to a lower end of the rack rail under the work scaffold by the worker connected to the work scaffold with the safety belt in a state where the passage is blocked with the poked and broken down granular powder;
opening the discharge port of the bottom portion of the hollow structure to discharge the granular powder stored in the passage; and
lowering the lifting body to the added rack rail to lower the work scaffold.
2. The method for discharging a granular powder brought into a fixed state inside a hollow structure according to claim 1 , wherein
the passage is a rat hole formed in a vertical direction in the granular powder stored in the hollow structure from the top surface of the granular powder to the discharge port of the bottom portion of the hollow structure by fixation and lamination of the granular powder in the hollow structure on an inner surface of the hollow structure and is formed before the method for discharging the granular powder is carried out.
3. The method for discharging a granular powder brought into a fixed state inside a hollow structure according to claim 1 , wherein the passage is an artificial hole formed in the vertical direction by boring in the granular powder brought into the fixed state in the hollow structure and is formed before the step of poking and breaking down the granular powder in the fixed state under the work scaffold by the worker connected to the work scaffold with the safety belt.
4. The method for discharging a granular powder brought into a fixed state inside a hollow structure according to claim 1 , wherein
the step of suspending the rack rail of a predetermined length into the upper space in the hollow structure from the opening formed in the ceiling portion of the hollow structure includes
repeating steps of temporarily placing the lifting body in the opening, inserting the rack rail into the lifting body from above,
driving a pinion provided inside the lifting body to send out the inserted rack rail below the lifting body,
stopping the sending-out once in a state where an upper end of the rack rail while being sent out projects from an upper portion of the lifting body,
adding a next rack rail to the upper end of the rack rail projecting from the upper portion of the lifting body, and
sending out the added rack rail below the lifting body.
5. The method for discharging a granular powder brought into a fixed state inside a hollow structure according to claim 4 , wherein
the step of lowering the lifting body moving along the rack rail from the opening to the upper space in the hollow structure along the rack rail includes
supporting the upper end of the rack rail projecting upward from the lifting body temporarily placed in the opening on a mount provided on the ceiling portion of the hollow structure,
releasing the temporal placement to the opening of the lifting body, and
driving the pinion provided inside the lifting body in a direction opposite to a direction when sending out the rack rail downward to thereby lower the lifting body along the rack rail from the opening.