A New Process For Compound Fertilizer Production From Melted Urea By Spraying Rotary Granulation

Based on the analysis of the present compound fertilizer production processes and the developing trend, a new process suitable for the Sichuan Tian Hua Limited company is selected and developed. By a spraying rotary granulation process using melted urea, this process effectively reduces the investment and makes the production process highly automation . Moreover, the component of the fertilizer product in this process is also very convenient to adjust.Depending on analysis to the process in theory and operation, the obtained optimal operation conditions are that the outlet temperature of granulator, cooler and dryer is about 60 , 70 and50, respectively, the inlet temperature of dryer is about 120, and the hot air flow rate is 28,00m3/h, the amount of 0.4MPa steam added must maintain the water content of the fertilizer from the granulator less than 4%. Through the pressure sprayer at 1.6Mpa, the product show a higher mechanical strength over 17N for a single granule, a good degree of sphericity over 0.8, and lower water content less than 1.4% by weight under the control of DCS. The openings of the shaking sieve are changed to rectangle from square, and the sieve is covered by a shield which effectively avoids the illusion of materials and improves the environmental condition. The fines in the flue gas are collected by a gravity settler and a wash tower and the result meets the need of environment that the concentration of the exhaust must be less than 30 mg/m3. The economical analysis shows that this process can create good economic benefit with a short investment refunding period and a good annual profit up to 4 million RMB after the taxes.