The drum granulator is the core equipment for fertilizer production, especially for compound fertilizers, organic-inorganic compound fertilizers, and some water-soluble fertilizer granules. Its parameters directly affect the granulation rate, particle strength, yield, and energy consumption. The following is a detailed explanation of key parameters, divided into three categories: process parameters, mechanical structure parameters, and supporting requirements, to help you accurately select or optimize production:
1、 Core process parameters (determining granulation effect)
Cylinder rotation speed (r/min):
Range: Typically 10-25 r/min (depending on diameter and process).
Function: Control the rolling state and retention time of materials. Low rotational speed, insufficient material rolling, and uneven particle formation; If the rotation speed is too high, the particles are easily broken and the granulation rate decreases.
Adjustment: A frequency converter with stepless speed regulation is required to adapt to different formulations and particle size requirements.
Cylinder inclination angle (°):
Range: usually 1 ° -5 ° (the larger the adjustable range, the better).
Function: Control the axial movement speed and retention time of materials inside the cylinder. The larger the inclination angle, the faster the material passes through, the shorter the particle growth time, and the smaller the particle size; The smaller the inclination angle, the longer the retention time, and the larger the particles, but they may be too wet or adhered.
Adjustment: The equipment should be designed with an adjustable tilt mechanism (hydraulic or mechanical).
Material filling rate (%):
Range: The optimal range is usually 20% -30% (proportion of cylinder cross-sectional area).
Function: Affects the rolling, collision, and bonding efficiency of particles. The filling rate is too low, resulting in fewer opportunities for particle collision and slower particle formation; The filling rate is too high, the material cannot roll smoothly, it is prone to clumping, and the particles are uneven.
Control: Adjust through the linkage of feed rate and cylinder speed/inclination angle.
Adhesive (liquid phase) addition method and location:
Method: Spray gun atomization (the most common and effective), drip addition.
Location: Multiple spray points are usually set within the length range of 1/3-1/2 of the cylinder at the feeding end.
Key: The atomization effect (droplet size), spray uniformity, and coverage area need to match the material's movement trajectory.
Granulation temperature (° C):
Range: 50-80 ° C (depending on material properties and binder).
Function: Affects the rate of water evaporation and particle hardening. Low temperature makes it difficult for moisture to evaporate, and the particles are soft and prone to deformation; Excessive temperature may cause material denaturation or wall sticking.
Control: Controlled hot air is usually introduced into the cylinder through a hot air stove and induced draft fan (associated with subsequent drying).
2、 Key mechanical structural parameters (determining equipment capability and lifespan)
Cylinder size (Dia × Length):
Mainstream models:
A diameter of 1.0m × 5m, 1.2m × 6m, 1.5m × 7m, 1.8m × 8m, 2.0m × 8m, 2.4m × 10m, 3.0m × 12m, etc.
Production relationship:
Roughly estimated (compound fertilizer): yield ≈ cylinder volume x filling rate x material bulk density x rotational speed coefficient x efficiency coefficient.
Experience reference (Φ 1.5m × 7m): about 3-5 t/h; Φ 2.4m × 10m: approximately 8-15 t/h.
Length to diameter ratio (L/D): usually 4:1 to 6:1. Large aspect ratio, long material retention time, suitable for the production of difficult to form particles or large particles.
Material and thickness of the cylinder:
Material: 304 or 316L stainless steel (standard, corrosion-resistant), special requirements can use lining wear-resistant materials (such as polymer board).
Thickness: Designed according to diameter and length to ensure rigidity (anti deformation), commonly 8-16mm (e.g. 12-14mm for a diameter 2.4m cylinder).
Internal structure:
Copying board (lifting board):
Types: Radial straight plate, angle bending plate, curved guide plate, etc.
Function: Elevate materials, form a waterfall like descent, and promote aggregation.
Layout: The feeding end can be encrypted or designed with special angles to prevent material sticking; The discharge end can be reduced or eliminated to promote discharge.
Retaining ring/blocking ring:
Used to control the axial movement speed of materials and prevent edge material retention.
Drive system:
Motor power (kW):
Range: from tens of kW (Φ 1.2m) to hundreds of kW (Φ 3.0m+).
Calculation basis: cylinder weight, material weight, frictional resistance, transmission efficiency.
Example: Φ 1.5m × 7m ≈ 18.5-22kW; Φ 2.4m × 10m ≈ 45-55kW.
Reducer: High torque hard tooth surface reducer (such as ZSY series).
Transmission mode: gear+ring gear (mainstream, reliable), roller friction transmission (rarely used).
Supporting structure:
Roller set: usually 2-3 sets, carrying the weight of the cylinder. The material needs to be wear-resistant (such as ZG55).
Wheel blocking set: prevent axial movement of the cylinder (hydraulic wheel blocking is preferred).
3、 Key parameters of supporting system
Hot air system (if drying function is required):
Hot air temperature (° C): 80-150 ° C (inlet), outlet temperature needs to be monitored to prevent too low (condensation) or too high (particle explosion).
Airflow (m ³/h): Calculated based on water evaporation rate.
Heat source: natural gas/diesel hot blast stove, coal-fired hot blast stove (requiring dust removal), steam heat exchanger.
Dust removal system (mandatory):
Airflow (m ³/h): Designed based on the outlet size of the cylinder and the dust content of the exhaust gas.
Equipment: Cyclone dust collector (primary)+water film/spray tower or bag filter (secondary fine dust collector).
Key: Exhaust emissions must meet local environmental standards (particulate matter concentration).
Control system:
Monitoring: cylinder speed, inclination angle, inlet and outlet temperature, hot air temperature/flow rate, motor current, vibration.
Adjustment: speed (variable frequency), tilt angle, hot air temperature/flow rate, adhesive flow rate, feed rate (interlock).
Automation: Advanced systems can integrate PLC/DCS to achieve automatic parameter optimization and recording.
4、 Key considerations in selection and use
Material adaptability is the core:
Powder characteristics: particle size distribution, flowability, viscosity, hygroscopicity, thermal sensitivity.
Adhesive properties: viscosity, surface tension, dosage, compatibility with materials.
Be sure to conduct material testing! Small/medium scale experiments have demonstrated particle size, optimal liquid phase volume, temperature, rotational speed, etc.
Three degree and one quantity linkage adjustment: The speed, inclination angle, temperature, and feed rate need to be adjusted together to find the optimal working condition.
Wear resistance and anti-corrosion:
The inner wall of the cylinder, the cutting plate, the inlet/outlet, and the lifting plate, which are prone to wear, require wear-resistant treatment (welding, lining plate).
The parts that come into contact with corrosive materials/steam must be made of stainless steel.
The experience of equipment manufacturers is crucial:
Examine successful cases and on-site operational effects of materials of the same type (especially your material).
Pay attention to the internal structural design details (layout of copied boards, anti sticking measures) and debugging capabilities.
Clear demand indicators (written into the contract):
Ensure production capacity (t/h)
Particle formation rate (%) (e.g. ≥ 85%)
Particle size range (mm) (e.g. 2-4.75mm, accounting for ≥ 90%)
Particle compressive strength (N) (according to product standards)
Stability of equipment operation (continuous running time)
Energy consumption index (kWh/t)
Material certificate (stainless steel grade, thickness)
