The regular operational life of a baghouse filter can be shortened by a number of factors. In this article we will discuss the top 4 reasons:
The deterioration of filter bags through abrasion can be a result of a number of causes. It can be caused by bags physically rubbing against each other, from the type of cleaning mechanism used or from where the dust enters the bag and impacts the fabric. The most common is caused by excessive particulate loads in the gas stream. Poor inlet design may lead to particulate laden air striking the filters in certain spots more than others such as near the bottom cuff, or strike the filters closest to the dirty-air inlet. In shaker baghouses, bags can deteriorate prematurely due to vigorous shaking particularly at points where the bags are attached. In pulse jet baghouses the repeated rubbing of the bags against the support cages (especially if the cages are bent or rusty) can considerably shorten the working life of the baghouse filter. This is usually the case when the filters are not sized properly to the cage (otherwise known as the correct amount of “pinch”).
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2. Exceeding Maximum Operating Temperature
Baghouse filters are manufactured using various materials depending on the application they are being used for. These materials have different thermal durability, that is the upper temperature limit of the fabric. Thermal durability may also be a potential cause of early failure. When operating temperatures rise above the designed limits of the fabric, whether for short spikes or longer overages, filters will begin to degrade and eventually fail. This may be a sudden failure such as the filters melting or catching fire or it could result in less obvious damage that causes the bags to become brittle. Changes in the plant process, fuel source, maintenance shutdowns of other systems, etc., may result in temperature spikes that will irreparably damage the filters.
3. Chemical Attack
Baghouse filter failure can also occur from a chemical attack. In its simplest form, this can be caused by using the wrong fabric for the chemical makeup of the gas stream. If gas stream characteristics are not taken into consideration when selecting the filter fabric and/or treatments/finishes, chemical attack can cause considerable damage to the baghouse filter. Other times unexpected changes occur in the gas stream that can cause changes in the composition of the gas. For example, operating temperatures may drop below the dew point allowing chemicals in the gas stream to condense on the filters. This can have a dramatic effect on the life span of a baghouse filter, therefore proper fabric selection and maintain tight control over the process operating conditions and procedures can help eliminate bag deterioration caused by chemical attack.
Premature baghouse filter failure can also be caused by fire. This could range from a relatively mild occurrence to a far more serious event. A minor event could be caused by an ember or a spark entering the baghouse system. The ignition source can then be drawn through baghouse system and make make its way to the surface of the filter causing a hole to be burnt in the bag or for it to catch fire.
Additionally, if the dust collection system is not working properly dust accumulations may form that can then provide fuel for a potential fire or explosion. If then a spark or ember enters the system this built up dust can ignite causing a fire, which can then be dragged through the entire system causing a serious or even catastrophic conflagration. This often happens when a system is choked off with high pressure drop (differential pressure) across the filters or when the dust discharge system (baghouse airlock and any connected screw/pneumatic conveyors downstream) do not remove the dust from the baghouse quickly enough.
A properly designed, installed and maintained system can go a long way in preventing premature baghouse filter failure. Following a regular preventative maintenance provided by a reputable dust collector OEM like Baghouse.com can keep your system in good working order. At times a dye leak test among other things can help technicians identify the exact cause of early filter failure.