7 Economical Ways to Improve the Performance of a Baghouse Dust Collector

The baghouse dust collector is an integral component to many industrial processes. However, many baghouses in operation do not offer adequate technology to accommodate today’s aggressive production demands. Thus, plant operators and owners are faced with one of three possible decisions concerning their inefficient baghouse: 

• Allow the baghouse to continue operating without modifications.
• Buy a new baghouse or upgrade the baghouse to a new, more efficient design, such as a pulse-jet, that can take advantage of high-efficiency pleated filter elements instead of filter bags and  cages.
• Make minor modifications and/or employ modestly priced devices and tools to improve the operation of the existing baghouse.

This article will focus on the last item and outline many cost-effective methods that can have an immediate impact on overall performance, without the need for a full rebuild of the baghouse.

1. Proper Design of New Equipment

Many baghouses in operation today were improperly designed from their inception, which may cause problems during the entire life of the baghouse. Some of these units were not engineered properly or were sized too small to save money in a budget decision. One of the most important aspects in design that is sometimes overlooked is a proper air-to-cloth ratio. 

This ratio is an expression that shows how much air volume is being handled versus how much cloth area is available in the baghouse. Pulse-jet baghouses that utilize felted material and clean while on-line can operate at higher air-to-cloth ratios. Shaker and reverse-air units that use woven material and clean off-line require more filter area.

The air-to-cloth ratio is a very important factor to consider in the design and operation of a baghouse. Improper ratios can contribute to inefficient operation of the baghouse. Operating at an air-to-cloth ratio that is too high may lead to a number of problems, including high pressure drops, insufficient cleaning and inadequate ventilation at the pickup point.

Shaker and reverse-air systems should not be sized to operate above a 2.5-to-1 air-to-cloth ratio.Most pulse-jet systems should be sized at no more than a 6-to-1 air-to-cloth ratio (and much lower on units that utilize fiberglass filter media). The correct design from the initial installation will definitely save money over the life of the unit.

2. Optimize Differential Pressure

Proper operation of a baghouse dust collector requires the use of differential pressure gauges on the entire collector. Gauges measure differential pressure by installing one port on the clean side and one port on the dirty side of the baghouse or plenum. 

By indicating a sudden decrease in pressure, a system leak can be detected. A sudden rise in pressure denotes the filter bags are becoming “blinded” or caked with particulate. Magnehelic gauges are available for point-of-use or remote installation.

U-tube manometers can also be used for the same purpose as Magnehelic gauges, but they are less technically advanced. These can also help identify problems with dampers and bags by indicating the difference in pressure across the baghouse.

3. Bag-to-Cage Fit

A major cause of failures in pulse-jet systems is improper fit of the filters to the support cage. For proper performance of the pulse-jet filters, the fit relationship between the bag and cage is critical. Filters that are too loose or too tight will severely limit collection efficiency and lead to premature failure.

A related area is the importance of the proper support cage to support the filter bag. There are many types of cages in the marketplace, but proper care must be taken to ensure that the cage construction will properly support the filter bag as well as optimize cleaning and efficiencies. The variables that are important for review include the number of vertical wires used and what type of ring spacing should be employed to operate properly in the dust collection equipment.

4,  Conditioning of New Bags

Conditioning agents are injected into a baghouse to establish a porous control layer on the filter bag surface. This protects the bags from particulate bleedthrough, blinding, and problems caused by hydrocarbons and moisture carryover. Conditioning agents should be utilized to pre-coat all carryover can lead to baghouse fires. These agents are of similar composition to the standard agents, but with the addition of spark-retarding chemicals.

As a spark comes into contact with the agent, a chemical reaction occurs that extinguishes the spark. Injection procedures should be available for all agents and should be followed exactly to ensure proper installation. This simple process will improve efficiencies and prolong filter bag life once in service.

 

                                          Incorrect (a) and correct (b) sequencing in pulse-jet systems

5, Correct Filter Bag Installation

Correct filter bag installation is important to maximize the life of the fabric. The recommended procedure for installing bags in pulse-jet collectors is to position all bag seams facing the same direction. This can provide a reference point that helps to identify problems that result from inlet abrasion. This can be a very useful troubleshooting technique that provides a history on bag failures. 

Bags with flanges or cuffs that fold over the tops of their support cages should be checked for smoothness around the edge to prevent leakage and bag abrasion. Seam placement on bottom-load bags should be 180° from the split or gap in the cage collar. The clamp on these bags should be installed 90° in relation to the seam on the bag and positioned on the groove in the cage. 

Snapband bags for top access pulse-jet units should be installed with the seams all facing the same direction. This allows for identification of areas where problems are occurring and improved troubleshooting of the unit. Filter bags installed in reverse-air collectors should have the seams positioned at a 45° angle to the walkway and access door, which allows for easy verification that seams are installed straight and plumb. This also ensures the bags are the maximum distance apart, reducing the potential for bag-to-bag abrasion.

6. Filter Bag Testing and Analysis

The only way to accurately analyze how a filter bag has performed while in operation is a filter bag analysis conducted by a reputable testing organization. Bags removed from the collector must be kept in their actual removal state so that accurate test results can be completed. 

The used filter bag should then be sealed completely in aproper container and sent to the testing laboratory.
Properly equipped laboratories will provide troubleshooting for fabric filters by doing complete lab testing on weight, breaking strength, permeability, mullen burst, flex cycles, and chemical analysis of the fabric and dust. 

Test reports should also be written in clear and concise language, complete with well-organized conclusions and recommendations. This information will then need to be evaluated against the current operating parameters of the equipment to make proper adjustments.Some labs also offer testing procedures that help in selecting the proper filter media for a baghouse.

 

7, Proper Sealing of Access Doors 

Access doors allow for maintenance personnel to enter the baghouse equipment for leak detection, filter bag changes and proper identification of operational problems. These doors need to create a positive seal to reduce baghouse air inleakage and heat loss on all negative systems. They also need to seal properly to reduce condensation that can cause bag failure and severe corrosion.

Care needs to be taken to ensure a positive contact between the door seal and the door pan to prevent air infiltration. Door seal material is used to help prevent the problems of metal corrosion and filter bag damage caused by inleakage of ambient air into the baghouse. 

There are various designs to meet all specific needs of many doors and applications based on gas chemistry, temperature, and door configuration. The proper use of door seal is a very inexpensive and easily installed fix that can prevent many problems from occurring. 

All doors should be inspected and analyzed to determine the materials are needed to properly seal the doors. This evaluation should be done on a periodic basis and whenever the baghouse equipment is down for repairs or changeouts.

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