Fertilizer manufacturing equipment – purpose of a prilling tower In which fertilizer process flowsheet is a prilling tower used to form solid spherical prills from a molten melt?

Introduction / Context:
“Prilling” converts a molten stream into near-spherical solid particles by dropping droplets down a tall tower with countercurrent air cooling. Identifying which fertilizer commonly uses prilling helps connect process equipment to product form and handling properties.

Given Data / Assumptions:

• Molten product capable of forming droplets that solidify in air.
• Desire for uniform particle size for storage, blending, and application.
• Alternative finishing routes include granulation and pastillation.

Concept / Approach:
Urea, produced from ammonia and carbon dioxide, exits the synthesis and concentration sections as a melt. This melt is commonly solidified in a prilling tower (or granulator) to form urea prills. Ammonia is liquefied or stored as anhydrous liquid but not prilled. Superphosphate and triple superphosphate are typically granulated or cured, not produced via prilling of a melt.

Step-by-Step Solution:

Verification / Alternative check:
Plant layouts and vendor brochures show urea finishing units with prilling towers or fluidized-bed/granulation alternatives.

Why Other Options Are Wrong:

• Ammonia: Stored under pressure; not prilled.
• Superphosphate and triple superphosphate: Produced by acidulation and granulation, not by prilling a melt.

Common Pitfalls:
Confusing prilling (falling droplets) with granulation (agglomeration in rotating drums/pans or fluidized beds).

Final Answer:
urea