Agglomeration in the Spray Zone of a Spray Drier: Determining anAgglomeration Index

摘要

Agglomerated milk powders are produced by the dairy industry to give improved powderrndispersibility and flowability. Agglomeration occurs initially at the top of the spray drier, wherernspray droplets of milk concentrate contact the fines recycle stream. Successful agglomerationrndepends on the probabilities of particle collision followed by adhesion. The process ofrnagglomeration is complex and is best understood as a series of micro-level processes of dropletrnformation, coating, coalescence and drying. However, it is difficult to isolate and study each ofrnthese individual steps within the industrial situation. The measurable streams are the spray, thernpowder and the dry agglomerated product. Measurements in-between are difficult to obtainrnbecause the process is very rapid. Therefore, agglomeration performance is best measured by anrnindex that relates the properties of these measurable streams. This paper reviews existingrnagglomeration indices in the literature and offers some new suggestions. The experimental workrnwas performed on a small scale Niro spray drier installed with a specially designed powder curtainrnand spray.