I need some advice/ operating experiences on deciding the compressed air quality for the pulse-jet cleaning of filter bags that treats flue gases in a municipal solid waste (MSW) plant.
The cleaning will be decided on the pressure drop across the bag. When the drop is high, compressed air will be pulsed/shot on the inside of the bags which then flexes outwards. This releases the dust captured on the outside of the bags.
In some plants I have seen compressed air of quality specified to <0.1 Micron, +3 deg. C (37F) dew point and 0.01 mg/m3, while others have a dew point of -20 deg C (-4F)
We have had some damage to bags before when dew point air was high. However, this can be due to other problems such as upsets, misalignment of the air nozzles to bag, excessive operating temperatures. I do not know the actual causes, unfortunately.
The plant will treat 100,000Nm3/hr in 6 compartments. I anticipate ~200 bags of 200mm diameter x 5m long will be used in each compartment. For pulse cleaning, I expect to use air at 50Nm3/h per compartment. Moisture content in flue gas is 20%. The flue gas temperature is 180 deg. C while the ambient temperature is always +/-25 deg. C and there is no winter/ freezing.
My main point of concern is if compressed air of a high dew point say +3 deg. C is used will this cause any damage to the bags due to its high moisture content? I looked at the physics of the problem. My conclusion is that the due to the relatively low consumption of compressed air used versus the actual amount of flue gases past the bags and the flue gas moisture content, this compressed air quality is a non-issue.
Question is: am I right or is there something that I am missing here?
Thanks.
Kai
The cleaning will be decided on the pressure drop across the bag. When the drop is high, compressed air will be pulsed/shot on the inside of the bags which then flexes outwards. This releases the dust captured on the outside of the bags.
In some plants I have seen compressed air of quality specified to <0.1 Micron, +3 deg. C (37F) dew point and 0.01 mg/m3, while others have a dew point of -20 deg C (-4F)
We have had some damage to bags before when dew point air was high. However, this can be due to other problems such as upsets, misalignment of the air nozzles to bag, excessive operating temperatures. I do not know the actual causes, unfortunately.
The plant will treat 100,000Nm3/hr in 6 compartments. I anticipate ~200 bags of 200mm diameter x 5m long will be used in each compartment. For pulse cleaning, I expect to use air at 50Nm3/h per compartment. Moisture content in flue gas is 20%. The flue gas temperature is 180 deg. C while the ambient temperature is always +/-25 deg. C and there is no winter/ freezing.
My main point of concern is if compressed air of a high dew point say +3 deg. C is used will this cause any damage to the bags due to its high moisture content? I looked at the physics of the problem. My conclusion is that the due to the relatively low consumption of compressed air used versus the actual amount of flue gases past the bags and the flue gas moisture content, this compressed air quality is a non-issue.
Question is: am I right or is there something that I am missing here?
Thanks.
Kai
