The pneumatic conveying technology of double casing pipe with positive pressure and dense phase has been widely used in coal-fired power plants.In the practical application of double casing pipe

serious wear occurs in the tube certain part including both the inner and outer pipe. Analysis show that

due to the gap existed in connection joint of the two pipes

the compressed air sprays from the gap with high speed

which changes the normal state of conveying material and formes the irregular strong turbulence

leading to serious wear of the pipeline.Thus

the connection way of inside pipe was reformed to the ferrule tube fitting to eliminate the connection gap

making the working condition back to normal in the section of two pipe connection area.The problem was solved completely.