Research and Discussion on Abnormalities in the Production of Powdered Ammonium Phosphate

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Dear colleagues, in order to expand our market share and increase product diversity, the company began producing ammonium phosphate powder in 2015, on top of its existing production capacity of 150,000 tons of granular ammonium phosphate. The purity of this powdered product is 60%-58%, with a production volume of 150,000 tons. We would like to share with you the performance metrics obtained over the past six months of operation, and we welcome your feedback on any shortcomings in our production process. The phosphoric acid concentration is 21-22%; the slurry density ranges from 1.50-1.51 (this value can rise to 1.53-1.54 after heating following the double-effect concentration process). The vacuum level in the second stage of the process is -0.055 MPa. The current production capacity of the system is 480 tons per day. The specifications of the powder spraying tower are Ø9600X36000; the diameter of the bed layer is 4500, and the diameter of the air outlet holes is 7.0 mm*8, with a total of 3200 such holes. The air volume delivered by the blower is Q=130,000 m3/h, with a pressure of H=9,000 Pa. The area of the air heater is F=2,000 m2. The temperature in the gas chamber ranges from 140-160°C, the pressure at the top of the gas chamber is 2,200 Pa, while the overall pressure in the gas chamber is 6,500 Pa. The moisture content of the product is less than 1.0%. Existing problems include: 1. The sealing balls and plungers of the piston pump have a short service life, resulting in high maintenance costs. 2. Scarring occurs in the powder spraying tower; in severe cases, the entire bed layer becomes scarred. In more common situations, scarring appears in localized areas, and the temperature of the material in those areas rises to 140–160°C. 3. There is no material layer in the powder spraying tower – even though the height of the outlet plate has been increased to 500 mm, no material layer remains there