Problems with the operation of the urea high-pressure system
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Due to the inaccurate liquid level in our synthesis tower, which generally ranges between 40% and 60%, the level changes in a linear manner – either dropping or rising steadily. As a result, the capacity of the synthesis tower is relatively low; it was previously used to produce 300,000 tons per year, but now it produces only 450,000 tons per year. The headspace available is also limited. Here, we operate the high-pressure system, and the speed of the ammonia pump is often adjusted by a few degrees; the outlet valve of the synthesis tower is also frequently adjusted, with it being turned on and off repeatedly. In my opinion, this approach isn’t very good. How do you guys operate the high-pressure system?
I don’t understand the ammonia stripping method and the full aqueous solution circulation method; is there an obvious liquid level indicator in the synthesis tower? (Rays or something else?) ) Could you let me know?
The carbon dioxide gas method uses a thallium source for level measurement.
The liquid level is inaccurate; try not to adjust the load when the liquid level is visible. After controlling the ammonia-to-carbon ratio, find an appropriate setting for the outlet valve of the synthesis tower, so that the liquid level can remain relatively stable. If the rise is gradual, the speed of the methylammonium pump can be reduced slightly, but not by too much – 1–2 revolutions is sufficient. Increase the speed of the ammonia pump slightly as the liquid level drops slowly. If the liquid level rises or falls after adjustment, the original rotation speed should be restored. The liquid level in the synthesis tower can be stabilized by making slight adjustments to the speed of the ammonia pump or the ammonium pump. Be sure not to make adjustments in multiple directions at the same time, otherwise stability will not be achieved.
The main thing to monitor here is the ammonia consumption; therefore, these people keep opening and closing the discharge valve – whenever the liquid level rises slightly, they open the discharge valve. Additionally, there is a specification regarding the outlet temperature of the high-pressure methamine condenser, which must not exceed 168.3 degrees. When the temperature rises, more ammonia is added, and when it drops, less ammonia is added
Frequent operation of the liquid discharge valve indicates poor operational skills; when the load is stable, the valve does not need to move
In devices that operate in continuous production, evaluating consumption leads to fierce competition among different teams, thereby making the system less stable. We have experience in this area. Assessment is possible, but it should be moderate.
Upstairs, how do you conduct assessments? What specific methods do you use?