Application of pulse bag dust collector in organic fertilizer granulation and drying industry

The granulation and drying process of organic fertilizer (such as the fermentation, granulation, and drying of raw materials such as chicken manure, straw, and food waste) generates a large amount of dust. This dust is primarily composed of organic debris, uncomposted particles, salt, and trace amounts of ammonia. It is characterized by high humidity (30%-50% moisture content before drying), strong viscosity (including oils and fats), and prone to compaction.

Pulse bag dust collectors, with their high-efficiency filtration, strong adaptability, and material recyclability, have become core equipment for dust control in this industry.

The following analysis focuses on industry characteristics, technical suitability, and optimization solutions:

I. Dust Characteristics and Control Needs in the Organic Fertilizer Industry

1. Core Dust Characteristics

High Moisture and Viscosity: Dust after granulation and before drying has a high moisture content (20%-30%) and is mixed with incompletely decomposed organic matter (such as grease from food waste), easily adhering to the inner walls of equipment and forming lumps.

Broad Particle Size Distribution: Particles ranging from 10 to 200 μm account for 70%, with fine particles (<50 μm) easily dispersing with airflow and requiring high-efficiency filtration materials for interception.

Corrosiveness and Odor: Contains small amounts of ammonia (NH₃) and hydrogen sulfide (H₂S), which may corrode equipment over long-term operation. Dust also carries fermentation odors, requiring coordinated control.

2. Core Control Needs

Purification Efficiency: Must meet the "Comprehensive Emission Standards for Air Pollutants," with particulate matter emission concentrations ≤30 mg/m³ and workshop dust concentrations ≤10 mg/m³.

Material Recovery: Collected dust contains a high amount of organic matter and can be reused in the granulation process, reducing raw material loss (typically 3%-5% of raw materials can be recovered).

Anti-blocking and Anti-sticking: High-humidity dust-induced filter bag sticking and pipe blockage must be addressed to ensure continuous equipment operation.

II. Technical Compatibility of Pulse Bag Dust Collectors

1. Working Principle and Industry Compatibility

Pulse bag dust collectors filter dust-laden air through filter bags, trapping dust on the bag surface. Periodically, 0.3-0.5 MPa compressed air pulses are used to clean the dust, ensuring that the purified air meets emission standards.

Their core compatibility lies in:

High-efficiency filtration: When using heat-resistant, anti-stick filter media, the filtration efficiency of organic fertilizer dust can reach 99.9%, effectively intercepting fine particles (<50μm).

Dry recovery: This eliminates the loss of organic matter associated with wet dust removal. Collected dust can be directly reused in granulation after screening, saving approximately 5%-8% in annual raw material costs.

Flexible Control: The cleaning frequency can be adjusted (e.g., every 30-60 seconds) to address the adhesion of high-humidity dust.

2. Key Component Selection

Filter Bag Material:

Low-humidity dust after drying (moisture content <10%) → Polyester needle-punched felt (heat-resistant to 130°C, low cost, suitable for general organic fertilizer);

High-humidity/greasy dust before drying → PTFE-coated filter bags (water- and oil-repellent, heat-resistant to 150°C, excellent anti-stick properties, suitable for processing food waste organic fertilizer).

Cleaning System: Utilizes offline pulse cleaning (single chamber offline does not affect overall operation) with a high-flow nozzle (16-20mm diameter) to ensure thorough removal of dust from the filter bag surface.

Casing Material: Due to the presence of small amounts of corrosive gases, Q235 steel plate with epoxy primer anti-corrosion treatment or 304 stainless steel (for high-humidity conditions) is recommended.

III. Application Advantages and Optimized Design

1. Core Application Advantages

Stable Operation: Compared to cyclone dust collectors (which have an efficiency of less than 70% for dust particles <50μm), pulse bag dust collectors can maintain emission concentrations below 20mg/m³ for extended periods, meeting environmental protection requirements.

Manageable Costs: The filter bag replacement cycle is 6-12 months (depending on operating conditions), and the annual operating cost is approximately 60% of that of a wet dust collector (without wastewater treatment costs).

Resource Recycling: A case study at a chicken manure organic fertilizer plant shows that pulse bag dust collectors recover approximately 200 tons of dust annually, equivalent to raw material value exceeding 100,000 RMB.

2. Targeted Optimized Design

Pre-treatment Cooling: If the flue gas temperature after drying is >120°C, a heat exchanger should be added to cool it to below 80°C to prevent high-temperature aging of the filter bags.

Anti-condensation measures: Apply an insulation layer (50-80mm thick, thermal conductivity ≤0.05W/m·K) to the exterior of the housing to prevent condensation from forming on the filter bags in low-temperature environments.

Duct design: Ensure an inclination angle of ≥60°, install deflectors at elbows, and control air speeds between 18 and 22 m/s to minimize dust accumulation and clogging.

IV. Actual Case and Operational Results

Case Study: Granulation and Drying Line of a Straw Organic Fertilizer Plant with an Annual Production Capacity of 50,000 Tons

Dust Conditions: Flue gas dust concentration after drying: 1500-2000 mg/m³, 15% moisture content, 80-100°C, containing small amounts of straw fiber and salt.

Equipment Configuration:

Pulse Bag Dust Collector (15,000 m³/h air volume, 200 filter bags, PTFE-coated filter media);

Offline Pulse Cleaning (0.4 MPa pressure, 45-second cleaning interval);

Housing Insulation + 304 Stainless Steel Ash Hopper (Corrosion Resistance). Operational Results:

Emission concentrations stabilized at 15-20 mg/m³, and dust concentrations in the workshop dropped to 8 mg/m³.

Filter bag replacement intervals were 8 months, and 180 tons of dust were recovered annually for reuse in the granulation process, increasing raw material utilization by 4%.

The equipment's continuous operation failure rate was less than 5%, meeting 24-hour uninterrupted production requirements.

V. Precautions and Future Trends

Daily Maintenance: Check the filter bag pressure differential daily (normal range: 800-1500 Pa). If the pressure differential is excessive, clean or replace the filter bags promptly. Clean the ash hopper weekly to prevent dust accumulation.

Technological Upgrades: In the future, intelligent control systems can be integrated to dynamically adjust the cleaning frequency using dust concentration sensors and AI algorithms, further reducing energy consumption.

Antibacterial filter media (such as silver-loaded polyester felt) can be developed to inhibit the growth of microorganisms in dust and reduce odor.

Through optimized filter media and structural design, pulse bag dust collectors effectively address the challenges of high-humidity, sticky dust control in the organic fertilizer granulation and drying industry. They combine purification efficiency with resource recovery value, making them the preferred equipment for achieving environmental compliance and reducing costs and increasing efficiency in this industry.