Quality requirements for liquid ammonia used in urea production
Thread Content
As the title suggests, what are the requirements for the quality of liquid ammonia used for urea? What potential problems might arise from using recovered liquid ammonia in the synthesis of urea from coal gasification wastewater?
Requirements for liquid ammonia: Pressure: 2.5 MPa, Temperature: 9–40 degrees; NH3 ≥ 99.5% (by weight); Oil ≤ 10 ppm (by weight); Water + inert substances ≤ 0.5% (by weight)
Does the acidic substance (H2S) affect urea synthesis?
It has an impact! It will cause corrosion to pipes, equipment, and compressors～
The recovered ammonia certainly cannot be used in products such as urea
What problems might exist? The purity of ammonia meets the requirements
Purity is just one aspect; for example, it may contain carbon dioxide, hydrogen sulfide, etc., which can cause corrosion of the equipment. Trace impurities can also lead to a decrease in the urea conversion rate, and organic substances may accumulate in the system, posing risks. In short, the costs outweigh the benefits and the risks are too high
As a supplementary note, it is recommended not to rush into deciding to use the recovered ammonia for urea production. First, operate the ammonia recovery unit normally for over a year to address any issues related to operation and equipment corrosion, before considering its use in urea production. The process and equipment requirements for urea production are extremely stringent; to date, only a few companies in China have truly mastered this technology. There have been more than a dozen explosions in these production facilities, resulting in severe casualties – people there really dare nothing