2018 06 Baboo Caking of urea in summer season
In India the ambient temperature goes to 46-48 oC in peak summer. The prills temperature goes to higher i.e.in our plants, line-1- prills temperature is 70-72 oC and sometime reached 78 oC at higher plant load with recovery of urea solution and that of line-2- prills temperature is 64-66 oC without Bulk Flow cooling. The caking of urea fertilizer is investigated in a ware house of large scale in National Fertilizers plant. In this article the caking tendency of urea investigated in silo and urea bags. The main cause of caking is the growth of crystal bond on contact point of prills, the caking tendency increases with moisture, ammonia contents causes water to mitigate through the pile. This to increases the caking tendency. The effect of plant load, temperature, relative humidity, and storage time on the formation of a bridge between these particles was analysed. The objective was to describe the geometrical changes in the contact region and to measure the strength of the resulting inter particle bridge. Urea particles are used which are known for creating solid bridges under well-defined climatic conditions. The measurements indicate that unlike to isotropic materials the bridge between two particles has higher shear than tensile strength. Moreover, the strengthening of the bridges with storage time is very inhomogeneous. The effect of load, temperature, relative humidity, and storage are the main objective of the study.