Abstract: The sludge eliminating apparatus of the present invention consists of a plurality of metal cylinders having several protruding eliminating teeth and outflow passing grooves, a plurality of spacers positioned in-between metal cylinders, a supporting member having a water pressure plate and several circular plates each plate having several notches, the supporting member contacting one end of the last one of the metal cylinders, a fixing pin for penetrating and fixing the metal cylinders, the spacers and the supporting member, and an inserting hole formed at the center of the water pressure plate. The present invention can completely eliminate sludge remnant undetached from the protruding eliminating teeth's first scratching by a low pressure state in-between the circular plates generated by the conveying power of the apparatus and receiving higher water pressure. Further, the present invention can eliminate sludge in the pipes of the U-shaped heat exchanger by using a elastic supporting member.