Principle of operation and structure of rapid urea melting
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This post was last edited by lxq700918 on 2009-9-8 21:52. Dear HaiChuan, if anyone knows the melting principle and structure of the urea rapid melting tank, please share your knowledge. Thank you.
The rapid melting of urea relies on the principle that urea melts quickly when it comes into contact with water; urea and water can dissolve completely at very low temperatures. The urea melting tank is equipped with a jacket or coils; it comes with a mixer, and water can be added by connecting it to water pipes.
What the friend upstairs mentioned does exist at present, but it tends to cause an increase in the level of dicyandiamide. I’ve heard that a certain equipment manufacturer now produces a more advanced version that is very effective at controlling the level of dicyandiamide; it’s called rapid melting, and air is also used in this process.
The poster is very concerned about the formation of biuret. The primary condition for its formation is to control the melting temperature of urea; at lower temperatures, less biuret is produced. The purpose of adding water is to lower the melting temperature, and by doing so, the formation of biuret can be prevented. Using other methods that do not lower the temperature is of no benefit to the formation of biuret; if air is introduced, it will only increase the melting temperature. Do you think that’s possible?
The melting of the urea-based material takes place in a melting tank, where steam coils are used for melting; a small amount of water is added as well. There are stirring elements to ensure that the steam pressure remains appropriate, and the temperature of the steam pipes is kept at the level necessary for the formation of biuret. This approach should help to control the production of biuret. It’s just my personal opinion, for reference only.
Feitian Technology is right; their views are insightful. However, when urea is melted, the loss of effective nutrients also needs to be taken into account.
The urea rapid melting device used in our tall towers these days does not require water; there are no coils inside, instead, it features heating fins driven by two shafts.
There are many types of urea melters, and I disagree with the melting principle mentioned on the second floor; water must not be added during the melting of urea. The structure of melters includes multi-layer coils with stirring, as well as those with jackets and dual-axis stirring. The design with jackets and dual-axis stirring yields better results; many high-tower manufacturers use products from Henan Sanmenxia Haobo. Wuxi Xinlian produces tubular types with stirring, but their performance is not satisfactory. As for the formation of biuret, it is caused by excessively high melting temperatures and prolonged residence time of urine; it has nothing to do with the melter or the melting process, but rather results from operational factors.
Melting point: 132.70°C (101325 Pa). Enthalpy of fusion: 250 KJ/mol. Density (liquid): 1220 Kg/m3. Bulk density: 750 Kg/m3. Specific heat capacity (solid): 1.55 KJ/(Kg·K). Specific heat capacity (liquid): 2.09 KJ/(Kg·K). All of the above six values are related to melting.