Caking of powder detergents is not only a problem in process equipment but it also presents an obstacle for consumers using the product. Though this problem has existed for many years, little is fundamentally understood of the conditions that produce the cakes. An experimental investigation and mathematical modeling of the mechanism of caking will lead to a better understanding of these events. In this study the yield strength of sodium carbonate was measured as a function of consolidation pressure, the amount of water in the sample and the number of temperature cycles to which the powder was exposed. It was shown that sodium carbonate monohydrate tends to cake only with the addition of sodium carbonate decahydrate over a 24 hour cycle. It is believed that caking in this system depends on the conversion of monohydrate to higher order hydrates. This conversion leads to a system that loses and gains moisture of due to temperature fluctuations. This suggests that temperature or humidity fluctuations are a primary cause of caking and will be explored as part of this paper. The strength of the cakes also shows a strong dependence on the consolidation pressure and amount of moisture initially present in the sample.
展开▼
