Double roller granulator:
The double-roll extrusion granulator is a machine that employs a dry extrusion granulation process, primarily used for granulation in industries such as fertilizers, chemicals, pharmaceuticals, food processing, and dyes. It forms granules directly from dry powder materials through double-roll extrusion, eliminating the need for binders or water. By utilizing a room-temperature process that requires no drying, it can reduce subsequent drying costs by 30% to 50%. The complete equipment system features a compact, scientifically sound layout and advanced technology; it offers energy efficiency, generates no waste (solid, liquid, or gas), and ensures stable, reliable operation and easy maintenance.

Structural composition of the equipment:

The structural system of the double-roll extrusion granulator primarily comprises the following:

Feeding system: Typically includes a hopper, a screw feeder, and an adjustment mechanism. The hopper stores powdered material and may be equipped with an agitator to prevent bridging; the screw feeder conveys material uniformly, while the adjustment mechanism controls the feed rate.

Extrusion system: The core component, consisting of two parallel, counter-rotating rolls (pressure rolls). The rolls are made of high-strength alloy steel, with specially shaped grooves on their surfaces to enhance material gripping. The roll gap and pressure are adjustable, directly influencing the quality of the granules. One roll has a fixed axis, while the other utilizes an eccentric shaft design to ensure a precise, minute gap between the two rolls.

Drive system: Responsible for driving the extrusion rolls to rotate synchronously in opposite directions; it typically consists of a motor, a gearbox, couplings, and gears. In the DZJ-I model, the two rolls are driven by a pair of meshing gears, whereas in the DZJ-II model, they are driven directly by two output shafts from a specialized gearbox.

Pressurization unit: Supplies the high pressure required for extrusion and includes overload protection.

Crushing and granulation system: Crushes, granulates, and screens the extruded sheet-like material.

Equipment operating instructions:

1. Pre-start Preparation:

Place the equipment on a level surface and secure it, ensuring sufficient clearance around it for operation and maintenance.

Check the oil level in the gearbox and the lubrication points on the drive assembly; apply grease to all lubrication points.

Verify that electrical and power connections meet specifications; the machine may fail to start if the voltage is below 360V.

Check all fasteners to ensure connections are secure and intact.

Check the gap between the two rollers (factory setting is typically 1–1.5 mm; for organic fertilizer production, the gap should be 0.5–1 mm).

Check the vertical and horizontal alignment of the cavities between the two roller dies.

Verify the correct direction of rotation for all drive components.

Operators must possess basic mechanical knowledge and operational understanding, and must complete training before operating the machine.

2. Startup Procedure:

Clean any oil or debris from the feed hopper and the surfaces of the rollers.

Start the machine under no-load conditions; starting with material inside is strictly prohibited.

Turn on the power; begin feeding material slowly only after the machine is running smoothly without load and the current has stabilized.

Monitor current fluctuations when operating under full load.

3. Operational Monitoring:

Continuously monitor the temperature of the machine body.

If the gearbox bearing area becomes hot to the touch or emits abnormal noise, inspect it immediately and replenish the lubricant.

If the bearings at either end of the main unit's bearing housing become hot to the touch or emit abnormal noise, shut down the machine for inspection and apply grease.

Equipment maintenance methods:

1. Daily Maintenance:

After shutdown, clear residual material from the roller surfaces, feed inlet, and discharge outlet to prevent caking or corrosion.

Check the area around the equipment for debris.

Apply grease to the gears before startup.

2. Periodic Maintenance:

Apply grease to chains and sprockets every 7 days.

Replenish or replace grease in the bearing housings every three months.

Add gear oil to the speed reducer before initial use and change the oil every four months.

Fill the speed reducer with No. 0 gear oil or No. 30 machine oil; apply machine oil via drip lubrication to gears, chains, and sprockets; and apply calcium-based grease to other transmission components.

Periodically (every 50–100 hours of operation) inspect the rollers for wear.

Periodically check and tighten all screws and fasteners to prevent vibration and malfunctions caused by loosening.

3. Maintenance for Long-term Storage:

Thoroughly clean and lubricate the equipment.

Apply anti-rust treatment.

Common Equipment Issues and Solutions:

Issue 1: Granules fail to form spheres or appear as flat cakes

Causes: Insufficient material feed; excessive gap width; gap is narrower at the ends and wider in the middle

Solutions: Ensure adequate material feed; adjust the gap between the rollers; grind down the edges to reduce the gap width

Issue 2: Axial or circumferential misalignment of the briquetting pockets

Causes: Loose anchor bolts on the adjustment sleeve; loose fit between the roller shell and the shaft

Solutions: Align the pockets and tighten the bolts; replace the roller shell or the shaft

Issue 3: Roller wear

Solutions: Use high-hardness roller shells to extend equipment service life. For minor wear, adjust the roller gap to continue operation; for severe wear, replace the rollers

Issue 4: Insufficient granule strength

Solutions: Control material moisture content within an optimal range (typically 5%–10%); reduce the roller gap to increase extrusion pressure; regularly repair or replace worn roller surfaces; optimize the formula by adding an appropriate amount of binder

Issue 5: Material blockage

Solutions: Resolve by adjusting operating parameters and applying proper maintenance techniques

Operational Precautions:

Strictly prevent the entry of ferrous materials to avoid breaking the rollers.

Do not start the machine while loaded with material.

Monitor and control the moisture content and temperature of the material.

Avoid overloading and the use of substandard materials; shut down and inspect immediately if any abnormalities occur.