High-Tower Slurry Spray Granulation Equipment: Core Equipment for Compound Fertilizer Production

Basic Definition and Core Principle

Core Working Principle

1. Raw Material Melting and Mixing: Melt urea (or ammonium nitrate) at high temperature (above about 132.7℃), and fully mix it with raw materials such as ammonium phosphate and potassium chloride to form a uniform slurry.
2. High-Altitude Spray Atomization: The slurry is delivered to the top of the high tower through a conveying system, and sprayed into tiny droplets at high speed through a rotary nozzle (the diameter of the nozzle hole is usually 2.5-3.0mm).
3. Cooling, Solidification and Forming: During the falling process (the tower height is usually 90-120m), the droplets contact the cold air rising from the bottom of the tower in counter-current to complete heat exchange and cool and solidify into spherical particles.
4. Finished Product Processing: The particles fall into the bottom of the tower, and after screening and surface treatment (such as anti-caking coating), the final product is obtained.

 Equipment System Composition

Performance Characteristics and Advantages

Product Advantages

1. Excellent Particle Quality: The particles are uniform and round (particle size 2-4mm), with smooth and dense surface, high compressive strength (≥25N), and not easy to pulverize and break.
2. Good Physicochemical Properties: Low moisture content (<1%), low caking rate, acicular pores inside the particles, fast dissolution rate and high water solubility (≥90%).
3. Uniform Nutrient Distribution: Each particle has consistent nutrients without stratification, ensuring stable fertilization effect.

Process Advantages

1. No Drying Process Required: Utilize natural cooling and solidification, relatively low energy consumption, and reduce exhaust gas emission.
2. High Degree of Automation: Full computer control, reduce manual intervention, and ensure stable product quality.
3. Continuous Production: Can operate continuously for 24 hours with large production capacity (1000-3000 tons per day for a single tower).

Application Scope and Raw Material Limitations

Application Scope

• Mainly used for the production of high-concentration urea-based compound fertilizers (N≥22%), especially suitable for formulas with balanced NPK ratios.
• Suitable for producing water-soluble compound fertilizers for efficient fertilization methods such as drip irrigation and sprinkler irrigation.
• A supported agricultural project encouraged by the state, in line with the development direction of agricultural modernization.

Raw Material Limitations

1. Liquid Phase Requirement: The proportion of molten urea (or ammonium nitrate) shall not be less than 30% to ensure slurry fluidity.
2. Phosphorus Content Limit: Phosphorus content ≤15%. Excessively high phosphorus content is prone to cause high slurry viscosity and nozzle blockage.
3. Raw Material Purity Requirement: High-purity raw materials are required. Excessively high impurity content will affect product quality and equipment operation.
4. Formula Limit: Not suitable for low-nitrogen, high-phosphorus/high-potassium formulas, which are difficult to form stable slurry.

Advantages and Disadvantages Comparison

Industry Development Trends

1. Technical Optimization: Improvement of nozzle structure (anti-blocking and corrosion-resistant) to enhance equipment operation stability; optimization of mixing tank (adding thermal insulation and improving agitator) to improve slurry uniformity.
2. Development of Low-Tower Technology: Development of 60-80m low-tower process to reduce construction cost and technical difficulty while ensuring product quality.
3. Intelligent Upgrading: Introduction of AI control system to real-time monitor parameters such as slurry temperature, viscosity and air velocity to achieve precise control.
4. Environmental Protection Improvement: Optimization of tail gas treatment system to reduce dust emission; development of low-energy-consumption process to reduce carbon footprint.
5. Formula Expansion: Expanding the scope of applicable formulas through additive technology to produce low-nitrogen, high-phosphorus/high-potassium compound fertilizers.

Comparison with Other Granulation Processes

Key Technical Parameter Reference