High temperature flue gas treatment for dust bag filter

High temperature flue gas treatment for bag dust removal

Among all the flue gases that need to be treated, a part is the soot with high temperature. Such as high-temperature boiler smoke, various iron-making cupola smoke, some industrial kiln smoke, etc., and even some of the flue gas temperature is as high as about 550 ℃. If no cooling measures are taken before the high temperature dust is collected into the bag filter, bag burning will occur and the filter will be damaged.

So how to deal with high temperature smoke and dust?

1. High temperature coating

The anti-corrosion coating of the bag filter for high temperature flue gas is indispensable. Due to poor coating, it not only affects the appearance, but also accelerates corrosion and reduces the service life of the dust collector.

2. Insulation method

No matter how the ash hopper of the dust collector is arranged, the airflow will inevitably be blocked, so the thermal insulation method is adopted in the design. The structure of the thermal insulation layer is calculated according to the prevention of condensation.

3. Use high temperature dust removal bag

There are many varieties of high temperature dust removal bags and they are widely used. If the flue gas contains a certain amount of moisture or the flue gas is prone to condensation, it is necessary to choose a high temperature resistant dust removal bag that does not hydrolyze, such as P84.

4. Dust bag mouth way

When using a pulse bag filter to treat high temperature flue gas, it is necessary to prevent condensation on the part of the bag mouth from cooling. The temperature of the compressed air used for cleaning is low, and the temperature of the flue gas to be purified is relatively high. When the compressed air is sprayed into the dust bag through the blowing pipe, the compressed air is suddenly released, and the temperature around the bag mouth drops rapidly. When the temperature drops, the mouth of the dust bag with higher temperature is easy to cause condensation; if the compressed air quality is poor, water and oil, the condensation will be more serious.

5. Structural approach

In order to prevent condensation of the high-temperature flue gas after cooling, the area where the gas is blocked should be minimized first in the design of the internal structure of the bag filter. The dust collector enters from the lower part of the box according to the placement of the dust-laden air, and the outlet is arranged on the upper part of the box, on the same side as the inlet.

At this moment, the air flow will be stagnant in the lower area of the dust filter bag and the part opposite to the outlet, and dew is easy to condense due to heat dissipation and cooling on the wall of the box. In order to reduce the heat dissipation on the wall, it is planned to install a special method of reinforcing rib structure on the side of the box.

The environment-friendly non-asbestos gaskets and sealing materials used on the box should be materials that can withstand the set temperature.

6. Cooling method before the high temperature flue gas enters the dust collector

Since the temperature of the flue gas is as high as about 550°C, the existing general bag filter cannot be used to it. Therefore, three cooling and preventive measures are adopted when the flue gas enters the bag filter.