PPS filter bag anti-oxidation protective measures

PPS filter bag anti-oxidation protective measures

1. Establish and maintain a protective layer

It is an effective method to cut off the direct contact between the flue gas and the dust filter bag.

(1) Protect the dust layer: The filtration of dust-containing gas mainly depends on the dust layer. The first dust layer plays a more important role than the filter cloth. It greatly improves the dust removal efficiency and isolates the flue gas directly from the filter bag. Protect the dust filter bag. Therefore, protecting the primary dust layer can protect the filter bag from damage.

(2) Surface treatment of the filter material: The filter bag adopts some surface post-treatment methods to block the harmful components in the flue gas (including oxygen) from the direct effect of the filter material and damage it.

2. Reduce the oxygen content and consumption of compressed air

The volume ratio of oxygen in the air is 21%, which is relatively high. Therefore, reducing this part of the oxygen content is an important aspect.

(1) Use a compressed gas source for ash removal with very low oxygen content: If compressed nitrogen is used for ash removal, the oxygen content in the flue gas will not increase or even decrease.

(2) Adopt high-pressure pulse dust cleaning: Because compressed air has high pressure, high flow rate, and small flow, if the “online” mode is assisted, the amount of compressed air will be much smaller.

(3) Reduce the number of injections: The differential pressure control method is generally more scientific than the timing control, which can reduce the number of pulse injections, and reducing the number of injections means a reduction in the amount of compressed air mixed in.

(4) Reduce the residence time of compressed air: using online dust removal, the residence time of compressed air is less than 1 second, which can greatly shorten the reaction time, while the offline method will reach a few minutes.

(5) Reduce air leakage rate: improve manufacturing and installation quality and sealing effect, and reduce air mixing.

3. Increase drainage volume

Increase the amount of drainage. In fact, it reduces the amount of compressed air required.

(1) On-line dust removal: To increase the amount of drainage, it is necessary to use online dust removal. "Off-line" cleaning cuts off the flue gas passage of the warehouse, without the supplement of flue gas, the drainage effect will not be very satisfactory.

(2) Install a suitable venturi nozzle. The venturi has two functions: one is to increase the drainage flow; the other is to maintain the cleaning pressure to the bottom of the filter bag. The shape of the venturi is the ratio of the drainage air volume to the blowing air volume. Have a greater impact. When compressed air is sprayed into the venturi nozzle, the venturi nozzle acts as a jet pump, which generates negative pressure in the filter bag through the high-speed jet, which can suck up to 80% of the pulsed air volume from the upper part of the dust removal filter bag. The purified gas enters the dust bag through the venturi nozzle for dust removal.

(3) Use a small diameter filter bag: increase the specific surface area of the filter bag. In the case of the same air-to-cloth ratio, the volume is reduced, and the amount of compressed air required is also reduced.

4. Control to run at an appropriate temperature

The temperature is the condition of the oxidation reaction, so that the inlet temperature of the dust collector is reduced as much as possible, and the high temperature protection measures can play a great role. But the temperature cannot be too low, it should be higher than the dew point temperature. Otherwise, the moist flue gas will condense, and the water vapor will be absorbed by the powder cake on the surface of the filter bag, making the powder cake layer very sticky and difficult to remove. In severe cases, water vapor and powder cake will react, causing acid corrosion to the dust filter bag and the dust collector box.