To enable extemporaneous and simple removal of accumulated ash content and slag small pieces without opening a monitoring window.
In a melting furnace 1 having a casing 2 to surround a molten substance flowing down from a gate 12, a monitoring window device is capable of monitoring the gate 12 from below through a monitoring window 22 disposed at the lower part of a cylinder part 21 for monitoring situated protruding obliquely downward from the side wall of the casing 2. A purge nozzle 3 through which a gas flow is blown against sediment on the inner surface of the monitoring window 22 is disposed in the proper position of the cylinder part 21 for monitoring. Downward piping 4 for discharge extending to the inside of the casing 2 from the inside of the monitoring window 22 is situated as the sediment is guided under its own weight as a discharge passage for the blown-off sediment.
YAMAYA KATSUHIRO
OGATA KAZUO
MISHIMA SHUNICHI
