What should be done if urea is yellow in color and does not form good granules?
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This morning, the employees noticed that the urea was yellow in color, and its granules were of poor quality – only half of them existed, with it seeming as though half of the granules had been cut off. What should be done?
It’s a urine-water treatment device, I guess. The ammonia/CO2, which are the raw materials used to produce urea, may become contaminated by sulfides, oils, and organic substances present in coal, causing the urea to turn yellow (it may turn slightly red if the equipment is corroded). This has happened before; the urea particles become irregular in shape, and this isn’t necessarily related to the yellowing of the urea. It’s most likely that the nozzles used for granulation are clogged with dirt and need to be cleaned.
1. It is necessary to control the oil content in the feed gas CO2, as there are no water coolers in the fifth stage of the process design, making it impossible to remove oil from it. Oil-free lubrication can be used. 2. It is necessary to address the issue of the levels of organic sulfur and inorganic sulfur. 3. In the first-stage urea decomposition system, care must be taken to control the amount of secondary oxygen-supplementing air introduced. 4. A conical flask can be used to take samples from the urine pipeline for comparative analysis in order to determine the source of the yellow color. 5. During normal production, pay attention to maintaining a stable load to prevent oil from the secondary evaporator and surface cooler from introducing particles.
Following the experts’ advice, the ammonia system was inspected, and oil-water presence was detected； Stop the machine to check the granulation nozzle; there is a little dirt inside the nozzle ； Check the urine filter before the nozzle again; indeed, the filter element is damaged ； I wonder if there are any other reasons?
This post was last edited by lxq700918 on 2010-5-14 00:20. The particles are yellowish, and there is a lot of oil in the system; it’s necessary to determine whether this comes from within the system itself (such as the compressor, ammonia pump, ammonium pump, etc.) or from outside sources (such as liquid ammonia). The granulation is not good; it seems that impurities have been introduced, blocking the small holes in the nozzles.
The yellow color of the urea is caused by oil in the raw materials; the granulation is poor – only half of the material forms particles, and it seems that half of those particles get cut off. Large fluctuations in temperature can also cause this issue. Impurities in the nozzles, as well as foreign substances, can likewise lead to poor particle size.
It’s not just the materials that are oily; the CO2 gas contains too many sulfides, the urea particles are also yellow in color, and they can also cause corrosion to the equipment. Check it out.
Does yellowing indicate equipment corrosion, such as insufficient oxygen in the high-pressure system?
The main reason for the yellowish color of urea is the high oil content in the process medium of the synthetic feed gas compressor.
An article mentioned that benzene compounds are present in CO2 gas; when they enter urea production equipment, they react to form *** amines in the final product, which can cause the color to darken. Does anyone know the methods for the trace analysis of benzene?
Based on our company’s experience, yellowing is mainly caused by the following factors: the presence of machine oil during the freezing process of liquid ammonia； The process of using iron oxide for desulfurization has drawbacks ； If mechanical oil or impurities are present in the ammonia water recovered from other systems and introduced into this system, it can cause problems. Yellowing mostly occurs in the early stages of driving ； Or it occurs more often when the ammonia tank is emptied ；