Whether you’re a large commercial operation or a small business, managing dust collection is a serious consideration. There may be myriad (oftentimes contradictory) considerations, so the best solution is to consult with experts in the dust domain.
Life is full of choices. The trick is to ensure that you make the correct decisions. The problem is that the “obvious solution” may not, in fact, provide the best option depending on your specific circumstances.
In the case of dust collection, for example, there are two main options, dry dust collectors and wet dust collectors (scrubbers), but which type is right for you?
What Type of Dust Collector is Best: Wet, Dry, or Both?
Not surprisingly, a large part of deciding on a dust collection system is involved with the dust itself. Where is the dust collector to be deployed? Which air quality standards are you required to meet? What size (or range of sizes) of dust particles is involved? Is it required to recover and reuse any collected dust particles or to discard them? Is the dust combustible (something that can burn in air), flammable (a combustible material that can ignite at ambient temperatures), and/or explosive? Will the dust require special treatment and handling based on its being poisonous, toxic, corrosive, and/or carcinogenic? And, of course, what is your dust load -- that is, how much dust do you need to collect, handle, and (potentially) dispose of -- and how do you determine this value?
When it comes to the systems used to collect the dust, dry dust options include baghouse collectors, cartridge collectors, and reverse air cyclones. Baghouse collectors are the preferred solution for the largest dust loads, cartridge dust collectors may be a better choice for dry, free-flowing dust, and reverse air collectors may be the ideal option if you need to save on energy or have limited access to a supply of quality compressed air.
Dust collectors that use liquid are known as wet scrubbers. In these systems, the scrubbing liquid (usually water) is introduced to a gas stream containing the dust particles. Greater contact of the gas and liquid streams yields higher dust removal efficiency. Wet scrubbing options include impingement, venturi, eductor, and packed-tower scrubbers.
One very important point to note is that choosing between dry dust collection and a wet scrubbing option may not be a binary decision. In certain situations, the most advantageous solution may be to use representatives of the two types in combination.
Contradictory Considerations
Even if you know everything there is to know about the dust you wish to collect, and even if you are familiar with the various wet and dry dust collection techniques and technologies available, there are still “gotchas” lurking out there for the unwary.
Consider a large industrial mixer in which dust escapes as a dry material is added to a liquid, for example. One’s initial thought may be that, since the material itself is dry, a dry dust collection system may offer the best solution. In this case, however, the dust extraction fans may draw up moisture from the liquid in the mixer, resulting in the filters being blocked by a sticky gunk. Thus, even though the material itself is dry, a wet scrubber may offer the best option in this scenario.
Many types of dust are combustible, which can lead to explosions if not handled correctly. Examples include metals, coal, and most organic materials (flour, sugar...). The finer the particles, the greater the risk and the larger the potential for explosion. Using a wet scrubber minimizes the risk of explosion, so this may seem to be the obvious choice. In many applications, however, it is required to recover the collected product, which may be adversely affected by moisture. If a dry dust collection system is used, it must be designed with appropriate isolation solutions, suppression systems, dampers, and explosion vents.
How big of a dust collector system do I need?
In the case where space may be an issue, cartridge filters may offer a smaller footprint over baghouse dust collectors. However, many substances -- including salts, sugars, and cellulose particles (such as those from cotton and paper) are hygroscopic, which means they attract and hold onto water molecules from the surrounding environment. Cartridge filters cannot tolerate moisture because it makes them hard to clean. By comparison, the pulsing and flexing of baghouse filters dislodge the hygroscopic particles before they can gather and block the filter.
In some cases, there are myriad considerations that appear to contradict each other. For example, the majority of baghouse dry dust collectors are designed to be operated at 500°F or lower, but some industrial processes involve temperatures of 800°F or higher. One option is to equip baghouse filters with high-temperature filters made from ceramic materials, but these can be extremely expensive. An alternative is to use a wet scrubber, which can dramatically reduce the temperature of the dust being collected. However, this can lead to problems associated with the disposal or treatment of the ensuing slurry. In the case of a smaller company that doesn’t already have water treatment facilities available, using a third-party may be cost-prohibitive. By comparison, this may not be a consideration for a larger company that already has suitable water treatment capabilities available on-site. So, what would be the optimal solution in this case? It’s time to call in the experts...
Bring Us Your Problem
As we’ve seen, when it comes to dust collection, there may be myriad (oftentimes contradictory) considerations. In certain situations, the most advantageous solution may be to use a combination of both wet and dry dust collection systems. In all situations, your best starting point is to consult with experts in the dust domain.
There’s an old saying that goes: “If the only tool you have is a hammer, everything looks like a nail.” The underlying concept is that, when equipped only with limited tools, single-minded people apply them inappropriately or indiscriminately.
Unfortunately, this applies to a wide variety of situations, including dust collection. As we’ve discussed, many dust collection problems may potentially be addressed using either dry or wet techniques. The issue is that most developers of dust collection systems specialize either in dry dust collectors or in wet scrubber systems. As a result, when faced with a dust collection problem, they may be tempted to promote their own solutions, even if they know that better alternatives are available in terms of cost, efficiency, energy usage, and so forth.
By comparison, in addition to the fact that Sly, Inc. has been helping companies to collect their dust and run clean and efficient for over 100 years, we are one of the few designers and manufacturers to offer both wet and dry dust collection systems. Furthermore, we don’t believe in a mass-produced “one size fits all” approach; instead, the flexibility of our engineering techniques allows us to customize solutions to better fit the task at hand.
We have 100 years of expertise, and we love collaborating with our customers, so bring us your dust collection problem and we will work with you to develop and customize the optimal solution that fully addresses your unique operation and application requirements.
