How to Choose a Suitable Dust Collector for Dryers?

Dryers (such as grain dryers, sludge dryers, mineral dryers) generate a large amount of dusty flue gas during operation, which has the characteristics of high temperature, high humidity, high dust concentration (some up to 1000-5000g/m³), and different dust characteristics according to the dried materials. Choosing a suitable dust collector requires comprehensive consideration of flue gas temperature, humidity, dust concentration and material characteristics, and the key selection points are as follows:

First, adapt to high temperature and high humidity. The flue gas temperature of dryers is generally 80-200℃ (some high-temperature dryers can reach 300℃), and the relative humidity is ≥70%. The dust collector must have high temperature and moisture resistance: 1. For medium and low temperature dryers (≤130℃, such as grain dryers), pulse bag filters with polyester water-repellent oil-repellent filter bags are selected, and the equipment body is insulated to avoid dew formation. 2. For medium and high temperature dryers (130-200℃, such as mineral dryers), pulse bag filters with PPS or FMS filter bags are selected, which have good high-temperature and moisture resistance. 3. For high-temperature dryers (＞200℃, such as sludge incineration dryers), high-temperature resistant dust collectors (such as ceramic multi-tube dust collectors + high-temperature pulse bag filters) are selected, and the filter bags are made of PTFE or glass fiber materials.

Second, handle high dust concentration. The dust concentration of dryer flue gas is generally high, so pre-treatment devices must be configured to reduce the load of the dust collector. A cyclone dust collector is installed at the inlet of the dust collector to remove large-particle dust (≥10μm), reduce the dust concentration entering the filter bag, avoid filter bag wear and blockage, and extend the service life of the filter bag. For dust concentration ≥3000g/m³, a multi-stage cyclone pre-treatment device can be used to further reduce the dust concentration.

Third, match the dust characteristics of the dried materials. 1. For non-corrosive, non-viscous dust (such as grain dust, mineral dust), ordinary high-temperature filter bags (PPS, FMS) are selected. 2. For corrosive dust (such as chemical material dryers), filter bags with corrosion resistance (PTFE, FMS) are selected, and the equipment body is treated with anti-corrosion coating. 3. For viscous dust (such as sludge, organic material dryers), filter bags with anti-adhesion performance (PTFE coated) are selected, and the pulse cleaning frequency is appropriately increased to avoid dust adhesion and blockage. 4. For flammable dust (such as grain, wood chip dryers), the dust collector is equipped with anti-static and explosion-proof devices (anti-static filter bags, grounding, explosion-proof valves).

Fourth, select the appropriate dust collector type. 1. Pulse bag filter: The preferred type for most dryers, with high dust removal efficiency (≥99.9%), can capture fine dust, and can be customized according to temperature and humidity, suitable for most dryer types. 2. Ceramic multi-tube dust collector: Suitable for high-temperature, high-abrasion dryer flue gas (such as mineral dryers), with good high-temperature and wear resistance, but low dust removal efficiency (85-95%), generally used as pre-treatment equipment. 3. Wet dust collector: Suitable for high-temperature, high-humidity and highly corrosive dryer flue gas (such as chemical dryers), avoiding filter bag blockage caused by high humidity, but the treatment effect is general, and there is secondary water pollution.

Fifth, other considerations. The air volume of the dust collector should be 10-20% higher than the flue gas volume of the dryer to ensure that the flue gas is completely captured; the fan should be selected according to the system resistance and air volume, and high-temperature resistant fans should be used for high-temperature flue gas; the dust collector should be equipped with an automatic ash discharge system (star-shaped ash discharge valve, spiral conveyor) to timely discharge the collected dust and avoid dust accumulation.