title: Technical design and assessment of tube equipment using two-phase flow for cleaning and disinfection.
abstract: Most pipeline systems in dairy and food processing plants are cleaned by circulating cleaning solutions under pressure with a liquid pump. The flow of the circulated solutions is single-phase or flooded flow. Milking system pipelines are subject to special requirements which distinguish them from those in dairy and other food processing plants. Milking 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 condition during the milking process. Milking machine Clean-In-Place (CIP) systems have historically used flooded flow to circulate cleaning solutions. The force to move liquid, however, is typically the vacuum provided by the same vacuum pump used during milking, rather than a positive pressure liquid pump. As the size and complexity 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 large diameter pipelines. The power available to achieve adequate flow velocity is also limited. Air admission has been used to produce two-phase (air/water) slug flow and overcome some of the limitations of fully flooded CIP. Cycled air admission can reduce the amount of water required for circulation and increase flow velocities and thus enhance mechanical cleaning action. Cycled air admission has been implemented in the field largely through trial and error methods. There has been a lack of fundamental design information and testing protocols for air-injected milking machine CIP systems. This has resulted in mixed success in 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 CIP systems and methods for field assessment of these systems. Just as properly implemented air-injection can improve 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.
authors.affiliation: College of Agricultural and Life Sciences, University of Wisconsin-Madison, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Reinemann
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying / Q000295:instrumentation*; D004203:Disinfection / Q000295:instrumentation*; D004866:Equipment Contamination / Q000517:prevention & control; D004867:Equipment Design; D005511:Food Handling / Q000295:instrumentation*; D006801:Humans; D012307:Risk Factors; D014922:Wisconsin