Why does the liquid output from the gas tower have an elevated temperature when the conversion rate is low?
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The high pressure drop in the tubes of the air lift tower is what causes the urine to remain there for an extended period of time. This post was last edited by yunanshu on 2008-5-30 16:09.]
Yes, a low conversion rate results in low gas efficiency and high steam consumption.
When the conversion rate is low, the content of ammonium carbamate in the output from the synthesis tower increases, while the amount of urea produced decreases. As a result, more ammonia and carbon dioxide need to be stripped out in the stripping tower, which significantly affects the efficiency of stripping. This leads to an increase in the levels of ammonia, carbon dioxide, and ammonium carbamate in the liquid output from the stripping tower, a decrease in the specific heat of the urine, and an increase in temperature. At the same time, the resistance encountered by the synthesis liquid as it passes through the split tubes of the stripping tower increases, the residence time of each unit volume of synthesis liquid within the stripping tube is prolonged, and the temperature of the liquid exiting the tower also rises. The above are my personal opinions.
What’s the matter? Aren’t there any other urea veterans here to give us some guidance? Urgent!
The feed composition of the stripping tower plays an important role in its operational performance. If the urea synthesis reaction experiences a decrease in conversion rate due to factors such as an imbalance in the N/C ratio and H2O/Ur ratio, as well as high inert gas partial pressures in the system, the amount of unreacted substances in the urine increases. Under constant steam pressure in the shell side, this increases the load on the stripping tower, resulting in reduced gas efficiency and thus an increase in the amount of unreacted substances in the effluent. The increase in liquid volume leads to a thicker liquid film, which prolongs the residence time of the liquid within the tubes; as a result, the temperature of the effluent rises or even exceeds the optimal level
The conversion rate is low; since the urea formation reaction is endothermic, it will definitely cause the temperature to rise.
I don’t entirely agree with the views expressed above. I believe there are mainly two reasons for the low conversion rate and the overheating of the stripping tower: 1) An imbalance in the ammonia-to-carbon ratio in the system, as well as an imbalance in the water-to-carbon ratio; too much water entering the high-pressure section leads to high system pressure and a high temperature of the liquid coming out of the gas tower. Another possible reason is blockage of the pores in the liquid distributor at the upper part of the gas tower, which results in poor stripping efficiency, low system conversion rate, and a high temperature of the liquid output
In a sense, it represents a decrease in the vapor-liquid ratio!
What process are you looking at? Also, find out what is causing the low conversion rate? In China, the carbon dioxide stripping process and the ammonia self-stripping process (Snem) are commonly used; generally, very high water-to-carbon ratios or very low ammonia-to-carbon ratios result in high liquid outlet temperatures. In the carbon dioxide stripping process, issues such as clogged distribution heads, insufficient level of installation, and poor sealing can lead to a decrease in stripping efficiency and overheating of the liquid output. It is also possible that poor gas lift leads to a decrease in conversion rate; a comprehensive analysis taking into account the condition of the equipment and the process is required.