Urea analysis system
Thread Content
Let’s discuss the pressure issue in the urea decomposition system – why does the decomposition become ineffective at a pressure of 0.5 MPa?
I’m not quite sure what the original poster means – when the pressure drops to 0.5, it stops working. Is it because the steam pressure is too low and thus can’t get in?
To be precise, it’s not that there’s no effect anymore, but rather the effect is weaker – that would be a more accurate description. According to the principles of desorption, lower pressure is more conducive to desorption; however, excessively low pressure will increase the water content in the gas exiting the desorption tower, which is not favorable for the system’s water balance ； Conversely, the higher the pressure, the less favorable it is for desorption; although it is possible to reduce the water content in the gas exiting the desorption tower to a certain extent, the efficiency of desorption will decrease.
That’s true, but I think one thing is clear: no matter how high the pressure is, as long as it is lower than the vapor pressure, the separation system can still function. As for the issue on the third floor related to water content, I believe the main factor affecting this is pressure. The higher the pressure, the better the absorption efficiency of the aqueous solution, and as a result, the levels of ammonia and carbon dioxide in the reflux liquid increase proportionally, which leads to a decrease in the amount of water in the system. Here, the pressure in the urea decomposition system has been increased from the original design pressure of 0.3 MPa to 0.35 MPa. With the existing decomposition systems, it is difficult to meet the design requirements due to process and production load constraints. However, if the pressure is reduced from 0.35 MPa to 0.3 MPa, the concentration in the ammonia tank cannot be maintained at a stable level.
Let’s explore this: keeping our analysis pressure at 0.48 Mpa yields good results. The steam pressure is 0.55; a certain pressure corresponds to a certain temperature. We aim to keep the temperature at the bottom of the distillation tower around 160 degrees. If the pressure is too low, the desired temperature cannot be achieved, and the efficiency of distillation decreases. Although the principle behind distillation is sound, it is still necessary to consider controlling the temperature of the liquid being produced even at lower pressures within a certain range. Especially 0.5 doesn’t work; it’s a bit confusing. Are the feed components different?