SERVICE TIP

Troubleshooting A Baghouse

Dust Collectors on Concrete Batch Plants Come in Three Basic Types:

Shaker Type - Low Capacity Dust Collectors that are normally installed on cement and flyash silos. This unit draws in dust laden air by an electric blower or by displaced air passing through into a single filter bag compartment. To clean, the bags are shaken by an electric motor driven shaker assembly.

Reverse Air - Medium Capacity units. This unit usually consist of two or three filter compartments. To clean, the air reverses in one compartment while the other compartment or compartments still cleans dust laden air.

Jet Pulse- This system allows for continuous cleaning of all filter elements. Dust collected in filter cartridges is removed by surges of air sequences a few seconds apart. Any type of Dust Collection Equipment requires proper installation and maintenance. If the baghouse is installed, turned on, and forgotten about until it stops working, it may be too late for repairs. At that point the baghouse may have to be rebuilt or even scrapped.

Any type of Dust Collection Equipment requires proper installation and maintenance. If the baghouse is installed, turned on, and forgotten about until it stops working, it may be too late for repairs. At that point the baghouse may have to be rebuilt or even scrapped.

• Opacity Monitor

• Pressure Drop Monitor

• Flow Monitor

The most valuable tools, however, are your eyes, ears, nose, and brain. Use them to establish a good baseline of normal operating data so you can quickly identify

the causes of problems that occur.

• Check Pressure Drop

• Monitor Gas Flow Rate

• Observe Outlet, visually or with continuous monitor

• Monitor cleaning cycle

• Check compressed air on pulse jet baghouse

• Spot check bag connection condition

• Check all moving parts on shaker baghouse

• Check fan for material build up

• Inspect baghouse body for rust and holes

• Thoroughly inspect the bags

• Check ducting for dust build up

• Observe dampen valves for proper seating

• Check gaskets on all doors

• Check all welds and bolts

• Check hopper for wear

• Replace high wear parts on cleaning system

Basically, filter bags fail one of two ways: By physically tearing and ripping, or by blinding, in which case the filter bags become plugged and severely limit the flow of the gas stream. 

The most common cause of bag failure is overfilling the cement or flyash silos, and excessive transport truck blower pressure. The following tips should be followed:

• Inspect high level bin level indicators and visual / audible signals for proper operation to avoid silo overfill.
  
  

• Install Anti-Overfill system on silo fill lines which works with high level bin indicators to positively eliminate accidental overfilling of silos by transport operator.
  
  

• Shaker mechanisms should be run for two to three minutes after filling silo. Pulse Jet Dust Collectors should be operated according to manufactures instructions.
  
  

• Transport truck blower pressure should not exceed 10 P.S.I. to avoid silo and baghouse damage. 

Possible causes of short bag life included:

1. Excessive Bag Tension

2. Poor top cuff design

3. Chemical Attack

1. Bag to bag abrasion

2. Bag to structure abrasion

1. Poor bag to thimble Connection

2. Poor thimble design

3. Inlet dust abrasion

4. Lack of bag tension

5. Lack of bottom cuff

6. High gas to cloth ratio

1. Poor ring cover fit
2. Poor ring cover stitching
3. Bag to bag abrasion
4. Excessive reverse air flow
5. Rapid reinflation after bag cleaning or reverse air system
6. Insufficient null time before reversing flow

1. Excessive blower pressure
2. Excessive gas to cloth ratio

Inspecting and changing bags takes a long time and is the highest maintenance cost in a baghouse. Bag failures occur at varying times depending on the operation of the collector. The longer the time between bag change-outs the lower the maintenance cost to the owner.

It is important to keep track of the bag failure rate. This can be helpful in correcting any condition that would cause premature bag failure. In addition, it is helpful in scheduling a complete bag change-out at a convenient time.

(Author Unknown)
Posted 22 January 2001