Solutions for overpressure in urea systems using carbon dioxide stripping
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This post was last edited by Purification OK on 2016-3-27 at 12:01. Urgently seeking solutions for overpressure during the startup of urea production using the carbon dioxide stripping method, as well as low liquid temperature in the lower washer. The system was kept insulated and under pressure for 24 hours; during operation the pressure dropped to 5.0 MPA. After feeding the material, everything worked normally, and granulation proceeded as usual. After 3 hours of operation, the system pressure began to rise gradually until it exceeded the allowable level. The temperature of the liquid flowing out of the high-pressure washer was 147°C, which is on the low side and not high enough. Despite making adjustments over 4 hours, there was no improvement. Now, we have stopped the gas supply and started feeding the material again. I hope some expert can offer some advice to help resolve this issue.
The washer temperature is low; could there be a phenomenon of liquid overflowing from the synthesis tower? What is the suction capacity of the ejector, and is the backup pressure sufficient?
The pressure is too low at startup; a low temperature of the high-pressure washer indicates low ammonia and carbon levels. The system should be insulated to maintain pressure, and the pressure at startup should be no less than 7.0 MPA.
Could you be more specific? From what you describe, it seems that the N/C ratio is low
After sealing the tower and starting the machine, the components of the system will definitely become disrupted; it is preliminarily assumed that a high water-to-carbon ratio is responsible for the decrease in conversion rate as well as the high system pressure. It is recommended to reduce the load and adjust the frequency of the methylammonium pump to keep the system from operating under excessive pressure; the situation should improve within one shift.
This post was last edited by 1025199692 on 2016-3-31 at 11:20. What are the temperatures of the water inlet and outlet in your system? What were the temperatures before starting the machine, and what are they now? Was the tower not properly purged during the high-pressure washer operation, resulting in some blockage?
This post was last edited by 1025199692 on 2016-3-31 11:21. After starting up the operation, the water-to-carbon ratio will definitely increase, but the low liquid outlet temperature indicates a low level of NH3 during this process.