Drum Dryer Machine

Equipment Introduction

Fertilizer rotary dryer machiness are core drying equipment in organic fertilizer, compound fertilizer, and bio-organic fertilizer production lines. They are primarily used to dry granulated or fermented wet materials to a safe storage moisture content.

In fertilizer production, dryers typically refer to rotary drum dryers, a traditional type of drying equipment with outstanding advantages such as reliable operation, high operational flexibility, strong adaptability, and large processing capacity. This equipment is widely used in fertilizer, building materials, metallurgy, chemical, and cement industries.

Taking organic fertilizer drying as an example, this equipment can directly dry livestock manure with a moisture content as high as 70%-80% to a safe storage moisture content of 13% in a single pass. The entire process is carried out within a closed system, effectively reducing environmental pollution during the drying process. The dryer is aesthetically pleasing, easy to operate, provides uniform drying, has low energy consumption, a long service life, and is easy to maintain, making it an advanced drying equipment in the fertilizer production field.

Structural Components of the Equipment

The fertilizer dryer can be divided into five core systems:

1. Cylinder System: The cylinder is the main body of the equipment, typically welded from high-quality medium carbon steel plates. Lifting flights are installed on the inner wall. The distribution angle of the lifting flights is optimized to repeatedly lift the material to the top of the cylinder and evenly distribute it, forming a "material curtain," greatly increasing the contact area between the material and hot air, improving thermal efficiency, and preventing material from sticking to the wall.

2. Support Frame System: The support frame is welded from medium carbon steel plates and channel steel. The support rollers are made of high-quality corrosion-resistant and wear-resistant materials, some using integrated casting technology. The support rollers cooperate with the cylinder's roller belts to bear the weight of the rotating parts of the machine and allow the cylinder to expand and contract freely due to thermal expansion and contraction.

3. Transmission System: This system consists of a main motor, reducer, pulleys/V-belts, split pinion gears, and a large gear ring fixed to the cylinder. The electric motor, after being reduced in speed, drives a small gear, which in turn drives a large gear ring to rotate the cylinder at a set speed (typically 3–8 r/min) at a uniform speed. The drive transmission between the reducer and the main shaft is achieved through a cross-shaped block or nylon pin coupling, ensuring smooth operation.

4. Hot Air System (Heat Source)

This includes a hot-blast stove, burner, blower, and induced draft fan. Fuels can be natural gas, liquefied petroleum gas, diesel, heavy oil, coal, or biomass pellets. The hot air temperature is typically adjustable within the range of 150–700°C. The induced draft fan generates negative pressure, drawing hot air into the cylinder for heat exchange with the material.

5. Feeding, Discharging, and Dust Removal System

Feeding End: Equipped with a feed chute or screw feeder to ensure uniform entry of wet material into the cylinder.

Discharging End: Equipped with a star-shaped discharge valve or discharger to prevent cold air backflow.

Dust removal system: Equipped with cyclone dust collectors, wet dust collectors or bag dust collectors to purify dust-laden exhaust gas and ensure that dust emissions meet standards.

Raw Material Characteristics and Feeding Requirements

The dryer can process raw materials in the following forms: powdery, granular, lumpy, and high-moisture viscous materials:

1. High-moisture materials: Fresh livestock and poultry manure can have a moisture content of 70%–85%. It needs to be dehydrated to about 60% using a solid-liquid separator before entering the dryer, which can significantly reduce energy consumption.

2. Granulated materials: The moisture content of granules is usually 6%–16%, which can be directly fed into the dryer for secondary drying.

3. Heat-sensitive materials: Some organic materials (such as microbial organic fertilizer containing bacteria) require the hot air temperature to be controlled ≤200°C to prevent killing beneficial microorganisms or causing organic matter carbonization.

Working Principle

The entire machine is installed at a slight 2.5° tilt. The motor drives the cylinder to rotate continuously at low speed via a reducer and gear pair:

Feeding and Conveying: High-moisture fertilizer granules are fed into the cylinder from the high-end feed inlet;

Hot Air Heat Exchange: High-temperature hot air is generated by a hot air furnace and drawn into the cylinder under negative pressure by an induced draft fan, with two heat exchange modes: co-current (hot air and material flow in the same direction) and counter-current (hot air flow in opposite directions);

Lifting and Drying: Lifting plates inside the cylinder rotate with the cylinder, continuously lifting and dropping the material at the bottom to form a uniform material curtain. Hot air penetrates the material curtain and removes the internal moisture of the material;

Discharge and Transfer: With the cylinder tilted and the rotational thrust, the material slowly moves to the lower end and is discharged from the outlet after reaching the required drying standard;

Exhaust Gas Treatment: Dust-laden, humid exhaust gas enters a dust collector at the tail end of the cylinder for purification before being released into the atmosphere. The entire process of feeding, drying, and discharging is continuous and automated, enabling large-scale uninterrupted production.

Applications of the Equipment

Fertilizer dryers have a wide range of applications:

1. Organic Fertilizer Production (Core Application)

Drying of livestock and poultry manure: chicken manure, pig manure, cow manure, sheep manure, horse manure, duck manure, etc.

Organic waste treatment: straw, pasture, distiller's grains, medicinal residue, fruit pomace, sugarcane bagasse, corn sauce, sludge, etc.

Large-scale production of bio-organic fertilizer and commercial organic fertilizer

2. Compound Fertilizer and Blended Fertilizer Production

Drying of compound fertilizer and blended fertilizer granules

Drying of phosphate fertilizer, ammonium sulfate, and other fertilizer products

3. Other Industries

Roller dryers are also widely used in metallurgy, building materials, chemicals, cement, ore, clay, kaolin, feed, and other industries.

Standard Operating Procedures and Daily Maintenance Methods

(I) Standard Start-up and Start-up Sequence

Start-up Procedure (Preheat the hot air furnace 30 minutes in advance)

Pre-start checks: Clean the feed chute of any blockages and remove debris from the combustion chamber; check bearing and gear lubrication; confirm the equipment grounding protection is intact; check the fan, hot air regulating valve, and seals;

Ignite the hot air furnace and adjust the damper to stabilize the hot air temperature;

Start the following in sequence: induced draft fan motor → dryer main motor → wet material feeding conveyor → dry material discharge transfer equipment;

Feed at a uniform speed, monitor the discharge moisture content and exhaust gas temperature in real time, and fine-tune the hot air temperature and feeding speed.

Shutdown Procedure

Stop adding fuel to the hot air furnace 30 minutes before shutdown;

First, stop feeding and completely empty the material from the drum;

Turn off the dryer main motor;

After the residual heat in the drum has dissipated, turn off the induced draft fan and the discharge conveyor;

Clean any remaining clumps of material from the drum and maintain the lubricated components.

(II) Strict Safety Precautions for Operation

Do not open the furnace door or add fuel while the hot air furnace is still supplying air, to prevent backfire burns;

Personnel are prohibited from walking under the cylinder while the equipment is running, and opening the cover for maintenance or removing protective devices is prohibited;

Insulating gloves must be worn when operating the motor or cable in case of malfunction. Do not start the equipment if it lacks a proper grounding wire;

Only 12V low-voltage portable lights are permitted for internal maintenance lighting. High-voltage lights are prohibited;

When drying heat-sensitive bacterial fertilizer, the inlet air temperature must not exceed 250℃ to avoid microbial inactivation.

(III) Graded Lubrication and Maintenance Standards

Gear meshing parts: Apply grease before starting the machine daily;

Cylinder roller surface: Apply grease every 7 days;

All bearing chambers: Add/replace grease every 3 months;

Reducer: Add gear oil upon initial installation, replace all gear oil every 4 months;

Regular inspection of vulnerable parts: Check the wear of V-belts, lifting plates, and pins monthly, and prepare replacements in advance.

(iv) List of vulnerable parts (common consumable parts) Triangular transmission belt, bearings, pinion, large gear ring, cylinder roller, internal lifting plate, coupling pin, sealing felt strips at both ends.

Common Faults, Causes, and Standardized Solutions

Target Customers for the Equipment:

1. Organic Fertilizer and Bio-organic Fertilizer Production Enterprises: Fertilizer dryers are core equipment in organic fertilizer production lines with an annual output of 10,000-500,000 tons. Suitable for large-scale production enterprises processing organic waste such as livestock and poultry manure, urban sludge, and straw.

2. Compound Fertilizer and Blended Fertilizer Production Enterprises: The drying process for granular materials is indispensable in the production of compound and blended fertilizers. Suitable for the large-scale production of various fertilizer products.

3. Livestock Farms: Large-scale livestock farms (chicken farms, pig farms, cattle farms, etc.) that need to process livestock and poultry manure into commercial organic fertilizer.

4. Biomass Energy and Environmental Protection Enterprises: Enterprises that process organic waste such as distiller's grains, medicinal residues, fruit pomace, and sludge.

Equipment Application in Production Lines

In modern fertilizer production lines, the dryer is typically located after the granulator and before the cooler, forming a standard process chain of "granulation → drying → cooling → screening → packaging":

Fermentation/Ingredient Mixing → Crushing → Mixing → Granulation → Dryer → Cooler → Screening Machine → Coating Machine → Packaging Machine

Process Functions:

1. Secondary Dehydration: Reduces the moisture content of granulated particles from approximately 15%–25% to ≤10%, meeting storage and transportation standards.

2. High-Temperature Sterilization: Temperatures above 80°C during drying kill residual pathogens, insect eggs, and weed seeds in the material.

3. Granule Polishing: The rotating drum polishes the granules, improving their appearance and marketability.

4. Connection and Buffer: As a key node in a continuous production line, it balances the capacity fluctuations between upstream and downstream stages. For organic fertilizer production lines, a dryer can also be set up after fermentation and before granulation to reduce the moisture content of fermented materials from 40% to about 20%, which facilitates subsequent crushing and granulation.

Analysis of the advantages and disadvantages of the equipment