Control of the pressure control valve in the urea synthesis tower (full aqueous solution circulation)

P4 valves are generally automatic; manual control is used very rarely, as it is too dangerous. If not adjusted properly, overpressure can occur accidentally. The issue in your factory might be caused by improper settings of the control valve parameters, resulting in large fluctuations; the fact that the medium pressure stabilizes when manual adjustment is used clearly indicates a fault with the control valve.

Generally, manual control of valves provides better stability than automatic control, but it increases the workload for the operators; moreover, operators cannot keep monitoring and making adjustments at all times – even tigers take naps. In this sense, some valves should be set to automatic control; just as it was mentioned on the second floor, it’s better to use automatic control for the P4 valve. The poster is correct – usually, the pressure control valve of the urea synthesis tower (P4 valve) is operated in automatic mode; it can reflect the trends in various parameters and can also interact with other instruments. However, once automatic control is adopted, the system becomes unstable, especially with large fluctuations in medium pressure. Possible reasons for this include: 1. Unstable feeding of the three reactants, with fluctuations in flow rate, temperature, pressure, and composition. 2. There is a fault with the P4 valve itself or its control system; have the instruments checked, and it is also recommended to examine the settings of the PID parameters. 3. If the pressure controlled by the pitcher remains stable, it proves that there is no issue with the pressure measurement point; if it is unstable, further verification is needed. This post was last edited by Boating on the Five Lakes on 2009-3-14 23:08.]

It is understood that in actual production, the P4 valves in most aqueous urea plants are manually controlled. Automatic control can also be used, unless the ammonia synthesis plant system operates with great stability (the load on the ammonia synthesis systems of plants using coal as raw material may need to be more stable). As for the issue raised by the original poster, the reasons are likely as follows: First, the load in the previous section changes significantly; when P4 is under automatic control, its regulation cannot keep up, resulting in a lag. Second, the P4 valve is faulty and cannot achieve automatic control. Third, the operators in charge of urea control adjusted the settings too drastically, failing to make fine-tuned and frequent adjustments.

“ The feed of the three materials is unstable, with fluctuations in flow rate, temperature, pressure, and composition. ”If that’s the case, it won’t be very stable, whether manually or automatically. It can be said that in most cases with the full-circulation method for urea in aqueous solutions, the P4 setting is definitely automatic; it is impossible to ignore safety and use manual control instead.

The urea P4 process using the full-circulation aqueous solution method should be under automatic control; manual operation is far too unsafe. Manual control can be used for adjustments when the system is unstable, but otherwise it must be automated. Report the issue for maintenance or replacement as soon as possible.

The pressure control valve of the urea synthesis tower (P4 valve) is under automatic control; it can reflect the trends in various parameters and can also operate in conjunction with other instruments. Changing the valve to manual control increases the risk and is unsafe.

The urea P4 process using the full circulation of aqueous solutions should be under automatic control; manual operation is too unsafe