Spontaneous ignition of milk powders in a spray‐drying plant

Abstract

A company operating a spray‐drying plant for skimmed milk and fat‐filled powders asked the Fire Research Station for help in determining the cause of a series of fires. The subsequent investigation showed that the powders could undergo spontaneous ignition in certain circumstances. The thicknesses of powder deposit on the spray‐drier walls necessary for there to be a risk of self‐ignition were calculated. These were sufficiently close to those encountered in practice to suggest that self‐ignition represents a real problem. Mechanisms for the occurrence of fires in the fluid‐bed instantizers are also put forward. Preventive measures are suggested.

Fire and explosion hazards in the spray drying of milk

“…Apart from being able to say that whole milk and buttermilk probablypresent more of a problem than other products, a ranking of the rest cannot be made. However, it is apparent that the skim milk tested by Saprygin & Kiselev (1968) is more hazardous than the other two quoted and also the whole milk tested by the Fire Research Station (Beever, 1984). In addition the three powders tested by Beever (1984) from one creamery appear less hazardous than comparable powders tested by other authors.…”

“…However, it is apparent that the skim milk tested by Saprygin & Kiselev (1968) is more hazardous than the other two quoted and also the whole milk tested by the Fire Research Station (Beever, 1984). In addition the three powders tested by Beever (1984) from one creamery appear less hazardous than comparable powders tested by other authors. The test method used by all the workers was very similar so these differences cannot be attributed to that cause.…”

“…Various workers (Pisecky;Saprygin & Kiselev, 1968;Beever, 1984) have studied the variation in critical size with ambient temperature for self-ignition in milk and milk based powders. A summary drawn from the results is given in Table 1.…”

Fire and explosion hazards associated with milk spray drying operations*

“…This investigation is reported in detail by Beever (1984). Reay (1979) quoted a case where the atomizer wheel in a spray drier handling dairy products was given too much lubricating oil.…”