Laser Cleaning Of Sulfide Scale On Compressor Impeller Blade

In the project of "transforming natural gas from West to East", the surface of the integral centrifugal compressor impeller blades is often covered by sulfide scale, which causes abrasive wear and corrosive pitting because of the impurities that exist in gas such as water vapor and hydrogen sulfide. Direct discarding will cause enormous waste of resources owning to the large size and high manufacturing costs of the impeller. However, the sulfide scale becomes an obstacle to the remanufacturing process, so it is necessary to clean the sulfide scale firstly.The traditional cleaning methods, including pickling and sandblasting, are hazardous and environmentally destructive. Among multifarious surface preparations, laser cleaning is an environmentally friendly technique for direct removal of contaminants without altering or affecting bulk properties in numerous applications. Therefore, there is a huge technical study place of laser cleaning technique to clean sulfide scale of compressor impeller blade surface. The main researches of the thesis are as follows:(1) The sulfide scale was prepared in high pressure reaction kettle which simulated the real working environment. The result showed that the thickness of sulfide scale on compressor impeller blade surface increased as working time went on. The sulfide scale was divided into two layers gradually.(2) The mechanism of laser cleaning sulfide scale was analyzed and the characteristics of laser cleaning were revealed for explaining the reason of choosing pulse fiber laser. The mechanism interaction between laser and material was analyzed. The relationship between the cleaning force and the adhesive force was found. The result showed that the mechanism of laser cleaning of sulfide scale on impeller blade was spallation without oxidization.(3) The experiment platform for laser cleaning test was built. The surface before and after laser cleaning was investigated by SEM-EDS. The sulfide layer cleaning thresholds and the substrate damage threshold were obtained by the experimental study. The experimental result showed that both cleaning thresholds were less than damage threshold of substrate materials. Changes in surface topography before and after laser cleaning were investigated using 3D surface measurement. The surface roughness had reached the minimum after the blade surface sulfide scale was cleaned completely.