TECHNICAL DESIGN AND ASSESSMENT OF TUBE EQUIPMENT USING 2-PHASE FLOW FOR CLEANING AND DISINFECTION

Most pipeline systems in dairy and food processing plants are cleaned by circulating cleaning solutions under pressure with a liquid pump. T he flow of the circulated solutions is single-phase or flooded flow. M ilking system pipelines are subject to special requirements which dist inguish them from those in dairy and other food processing plants. Mil king system pipelines are considerably larger in diameter than product lines in dairy plants because they must carry both milk and air in a stratified flow rendition during the milking process. Milking machine Clean-In-Place (CIP) systems have historically used flooded flow to ci rculate cleaning solutions. The force to move liquid, however, is typi cally the vaccum provided by the same vacuum pump used during milking, rather than a positive pressure liquid pump. As the size and complexi ty of milking machines has increased in recent years, flooded flow CIP systems have become inadequate. The amount of water required to fully flood a milking system becomes impractical with very long and/or larg e diameter pipelines. The power available to achieve adequate flow vel ocity is also limited. Air admission has been used to produce two-phas e (air/water) slug flow and overcome some of the limitations of fully flooded CIP. Cycled air admission can reduce the amount of water requi red for circulation and increase flow Velocities and thus enhance mech anical cleaning action. Cycled air admission has been implemented in t he field largely through tiral and error methods. There has been a lac k of fundamental design information and testing protocols for air-inje cted milking machine CIP systems. This has resulted in mixed success i n the application of air injected systems. This paper summarizes both laboratory and field research conducted at the University of Wisconsin Milking Research and Instruction lab to provide basic information for the design of air injected CTP systems and methods for field assessme nt of these systems. Just as properly implemented air-injection can im prove cleaning and sanitation in milking machines with less water and energy, so to it may have applications in the cleaning of other types of tube equipment.