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Factors Affecting the Formation of Biuret and Its Formation Process I. In production, the formation of biuret is primarily related to urine concentration, ammonia partial pressure, temperature, and residence time; these factors are discussed as follows: (1) Relationship with urine concentration: When a urea solution is heated at a constant temperature, as the urine concentration increases, the rate of biuret formation accelerates； ⑵Relationship with ammonia partial pressure: As the ammonia partial pressure increases, the content of biuret **decreases** ； ⑶Relationship with temperature: At a certain urine concentration, the rate of biuret formation increases as the temperature rises ； ⑷Relationship with residence time: As the residence time increases, the urea formation rate also increases. II. The increase in biuret during the urea production process: The liquid coming out of the urea synthesis tower contains 0.3–0.4% (W) of biuret; after the first stage of decomposition, this amount rises to 0.5%, and after the second stage it increases to 0.6%. After evaporation in the first stage, the concentration reaches 0.7%, and after evaporation in the second stage it rises to 0.75%. Finally, after granulation using spray nozzles, the concentration reaches 0.9%. III. Main equipment: Stage I and Stage II evaporators. The two-stage evaporator is a combined device of a two-stage evaporation heater and a separator; the urine from the first stage of evaporation enters the heater through pipes. Due to the low pressure, urine passes through the heating tube in just a few thousandths of a second, reducing the formation of biuret. The gas-liquid separator consists of two parts. A vane separator is installed at the outlet end of the heater, where a large number of liquid droplets are captured in the vane channels ； The mist droplets entrained by the rising steam are captured in the top swirl plate separator, and an annular flushing water pipe is provided to prevent urea crystallization on the swirl plate fins.