The correct use of cyclone dust collectors

Abstract

Cyclone dust collectors rely on the rapid rotation of dusty gas within the dust collector and the centrifugal force to separate particulate dust from the gas. Therefore, their structure and principle are completely different from those of other mechanical dust collectors, and their operation, maintenance and management are particularly important. The operation of a cyclone dust collector includes start-up, operation and shutdown. The maintenance work mainly involves the analysis, elimination and prevention of common faults.

Key words

Operation, maintenance and management of cyclone dust removal for particulate dust

The correct operation of the cyclone dust collector

1.1 Preparations before Startup

1) Check whether all connection parts are firmly connected.

2) Check the airtightness of the junctions between the dust collector and the flue, the dust collector and the ash hopper, the ash hopper and the ash discharge device, ash conveying device, etc., and eliminate the phenomena of ash leakage and air leakage.

3) Close the baffle valve slightly, start the ventilator. After no abnormal phenomena are observed, gradually open the baffle valve wider to allow the dust collector to pass through the specified amount of dusty gas.

1.2 Technical Requirements during operation

1) Pay attention to the changes in easily worn parts such as the inner wall of the outer cylinder.

2) When the temperature of the dusty gas changes or the humidity drops, pay attention to the adhesion, blockage and corrosion of dust.

3) Pay attention to the changes in pressure difference and the color of the discharged smoke. Wear and corrosion can cause perforation in the dust collector and lead to dust emissions, resulting in a decline in dust removal efficiency, deterioration of exhaust smoke color, and changes in pressure difference.

4) Pay attention to the airtightness of all parts of the dust collector and check the changes in the gas flow rate of the cyclone cylinder and the dust collection concentration.

1.3 Technical work after the assignment

To prevent the adhesion and corrosion of dust, the dust collector should continue to operate for a period of time after the dust removal operation is completed. Only when the dust collector is completely replaced by clean air can the operation of the dust collector be stopped.

2) Eliminate the dust adhering to the inner cylinder, outer cylinder and blades, and clear the dust in the ash hopper.

3) Repair perforations caused by wear and corrosion when necessary.

4) Check the airtightness of all parts and replace the sealing elements if necessary.

5) Carry out routine maintenance of the fan in accordance with the provisions of the user manual.

Maintenance of cyclone dust collectors

When the cyclone dust collector is in operation, it is necessary to stabilize the operating parameters, prevent air leakage and wear of key parts, and avoid dust blockage; otherwise, it will seriously affect the dust removal effect.

2.1 Stable operating parameters

The operating parameters of a cyclone dust collector mainly include: the inlet air flow velocity of the dust collector, the temperature of the treated gas, and the inlet mass concentration of the dusty gas, etc.

1) Inlet airflow velocity. For a cyclone dust collector of a certain size, an increase in the inlet air flow velocity not only raises the gas processing volume but also effectively enhances the separation efficiency, but the pressure drop also increases accordingly. When the inlet air flow velocity increases to a certain value, the separation efficiency may decline accordingly, wear intensifies, and the service life of the dust collector shortens. Therefore, the inlet air flow velocity should be controlled within the range of 18 to 23m/s.

2) The temperature of the gas being processed. As the temperature of the gas rises, its viscosity increases, which intensifies the centripetal force acting on the dust particles, and thus the separation efficiency decreases. Therefore, dust collectors operating under high-temperature conditions should have a relatively large inlet air flow velocity and a relatively small cross-sectional flow velocity.

3) The inlet mass concentration of the dusty gas. When the concentration is high, large particle dust has a significant carrying effect on small particle dust, which is manifested as an improvement in separation efficiency.

2.2 Prevent air leakage

Once a cyclone dust collector leaks air, it will seriously affect the dust removal effect. It is estimated that when there is a 1% air leakage at the lower cone of the dust collector or the ash discharge valve, the dust removal efficiency will drop by 5%. When the air leakage is 5%, the dust removal efficiency will drop by 30%. There are three types of air leakage in a cyclone dust collector: the connection flanges at the inlet and outlet, the body of the dust collector, and the ash discharge device. The causes of air leakage are as follows:

The air leakage at the connection flange is mainly caused by the bolts not being tightened properly, the uneven thickness of the gasket, and the unevenness of the flange surface.

2) The main reason for air leakage in the dust collector body is wear, especially in the lower cone. Based on usage experience, when the dust mass concentration in the gas exceeds 10g/m ³, a 3mm steel plate can be worn out in less than 100 days.

3) The main reason for air leakage in the air unloading device is the poor sealing performance of the mechanical automatic type (such as the heavy hammer type) ash unloading valve.

2.3 Prevent wear and tear on key parts

The factors influencing the wear of key parts include load, air flow velocity and dust particles. The worn parts include the shell, cone and dust outlet, etc. Technical measures to prevent wear and tear include

1) Prevent the dust exhaust port from being blocked. The main approach is to select high-quality ash discharge valves and strengthen the adjustment and maintenance of the ash discharge valves during use.

2) Prevent excessive gas from flowing back into the ash discharge port. The ash discharge valve used should be tight and the counterweight should be appropriate.

3) Regularly check whether the dust collector has any air leakage due to wear and tear, so as to take timely measures to eliminate it.

4) At the areas where dust particles impact, use replaceable anti-wear plates or add wear-resistant layers.

5) Minimize the number of welds and joints. Any necessary welds should be ground smooth. The inner diameters of the flange stop and gasket should be the same and maintain good alignment.

6) The tangential velocity of the airflow at the wall of the dust collector and the inlet airflow velocity should be maintained within the critical range.

2.4 Avoid dust blockage and dust accumulation

The clogging and dust accumulation of cyclone dust collectors mainly occur near the dust outlet, followed by in the intake and exhaust pipes.

Mouth blockage and preventive measures. There are usually two reasons for the blockage of the dust exhaust port: One is that large pieces of materials or debris (such as wood shavings, wood chips, plastic bags, shredded paper, rags, etc.) remain at the dust exhaust port, and then dust accumulates around it. The second reason is that too much dust has accumulated in the ash hopper and has not been discharged in time. Measures to prevent the dust exhaust port from being blocked include: adding a grid at the suction port; Add hand-drilled holes at the upper part of the dust exhaust port (with gaskets on the hole cover and sealant applied).

2) Air inlet blockage and its preventive measures. The blockage of intake and exhaust ports is mostly caused by improper design - even slight roughness, right angles, bevels, etc. at the intake and exhaust ports can lead to the adhesion and thickening of dust, eventually causing blockage.