Steven Brandon C and Paul Dawson L
Plugging often occurs when fluid foods are processed in parallel-tube devices (e.g., tubular heat exchangers and membrane filtration modules, especially when fluids are concentrated). Plugging reduces productivity by reducing performance and causing downtime to remove the plug. The cause of plugging is explained here for the first time and a means of avoiding it is described. Plugging rarely occurs during normal operation while fluid food is being pumped through the tubes, but rather when the tubes are flushed with water, e.g., prior to routine cleaning. The study identified two prerequisites for plugging to occur: tubes must have unequal resistances to flow and the fluid food must possess a yield stress that exceeds a value which depends on the device geometry.