The issue of two-stage evaporation temperature
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A high temperature in the second-stage evaporation leads to higher levels of biuret. So, if the temperature is lower, are there any other hazards besides the risk of pipe blockage? For example, in a two-stage vacuum with a pressure of 96.14 KPa and a temperature of 132.9°C, what are the potential hazards if the time exceeds 10 minutes?
The temperature is a bit low; the vacuum level is 96.15 Kpa, with a temperature of around 138°C. It may result in excessive moisture levels. In severe cases, it affects granulation
It is obvious that the temperature is not at the required level, resulting in high moisture content in the finished product; furthermore, this leads to pipe blockages.
The vacuum level is related to the local air pressure to some extent, but 132.9 is already the crystallization point. Apart from blockages in the pipes, issues such as blockages in the nozzles and poor granulation may also occur; as a result, the urine solidifies partially before it exits the nozzles, preventing proper granulation and leading to the formation of dust or lumps. Furthermore, if the Rongrong pump is self-sealing, it may cause the mechanical seal to be damaged frequently. Therefore, for evaporation control, the lower the temperature, the better. Within the range of high-quality products, it is necessary to consider the stable operation of the system. Thank you.
This post was last edited by Xieshui on 2010-4-23 at 20:46. The pressure for two-stage evaporation is 3.86 KPA (absolute), and the temperature is 132.9 degrees. If the thermometer is accurate, then the temperature is slightly above the crystallization temperature. Urine keeps flowing within the pipes; even if 10 minutes pass, crystallization and blockage do not occur immediately. Granulation can also be achieved using nozzles, but the quality of the particles will be poor. If the temperature measurement is inaccurate, or if the substance is exposed to that temperature for an extended period, especially during cold seasons, it’s hard to say what will happen. When faced with such conditions in the evaporation process, there’s no need to persist, particularly when it’s unclear what the subsequent process conditions will be (such as whether there’s enough steam). It’s safest to switch to a circulation mode and break the vacuum right away. Safety must be prioritized in production, and it’s necessary to adhere to process rules and procedures.
If the temperature does not meet the specified levels, the moisture content will definitely be too high, which affects granulation and leads to sticking to the tower, resulting in substandard quality of the finished product
The nozzle is partially blocked; urea particles turn into a powder form. Crystals also cause blockages in the pipes. High moisture levels pose another issue, and the melt pump loses pressure