An air preheater (APH) is a general term used to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process. They may be used alone or to replace a recuperative heat system or to replace a steam coil. Normal air preheater exist the problem of collection of ash,worn down,low temperature corrosion to effect the safe and economical operation for the boiler unit. So HTEG established the exclusive enamel research and development center to supply the complete solution and organize the scientific reserach personnel to tacle key problems and develop the new heat transfer parts-enameld tubes air preheater