Nothing to Sneeze At—5 Keys to Improving Dust Removal Efficiency

There are at least five keys to help improve your dust collection system and greatly reduce if not eliminate these consequences by increasing dust collection efficiencies for a cleaner, safer work environment and enhanced product quality and production.  

Five Keys to Improving the Efficiency of Your Dust Collection System 

Air filtration systems supply a critical function in almost every industry where the presence of dust can pose serious consequences that can impact workplace safety, air permit compliance, and ultimately corporate finances. These can include employee health, regulatory fines, air permit violations, damaged equipment, reduced product quality, and unplanned shutdowns—not to mention the bad press and costs associated with resolving these issues. 

These air filtration systems or more commonly called, dust collection systems, are engineered and designed to capture the majority of airborne particles that result from utility, industrial, mining, pharmaceutical, food-related or agricultural practices, before these particles can negatively impact worker and workplace safety, product quality,  plant production, and emissions to the environment.   

Dust collection systems help companies comply with air pollution control or air quality workplace standards established by federal, state or local governing bodies, including the Environmental Protection Agency (EPA), the National Fire Protection Association (NFPA), the Occupational Health and Safety Administration (OSHA), and more.  

 There are at least five keys to help improve your dust collection system and greatly reduce if not eliminate these consequences by increasing dust collection efficiencies for a cleaner, safer work environment and enhanced product quality and production.  

• System Design 
• Filter Bag Media/Material Selection 
• Proper Bag Installation 
• Regular Maintenance 
• System components 

System Design Establishes Firm Foundation for Dust Collection Efficiency 

System design impacts dust collection efficiency and operational costs from the start, with several factors playing a critical role in an engineered dust collection system. A pulse jet dust collection system, or a baghouse system, operates through a high-pressure air cleaning that discharges a pulse or blast of air through an air filter, or bag, that dislodges the majority of the dust cake for disposal. During the design phase, below are some of the important factors to consider when designing a baghouse: 

Air to cloth ratio—The air to cloth ratio ensures adequate surface area to capture the dust based on the flow rate. The type of material being captured as well as the inlet dust concentration and required removal efficiency are all factors used to determine the proper air to cloth ratio.  

Interstitial velocity—This factor is directly related to bulk density of the captured material. It is defined as the upward velocity of the air through the open area between the filter bags inside a dust collector. If it is too fast, when the controller pulses, the material will tend to stay in suspension and be recaptured on the bag rather than fall into the hopper. 

Material characteristics—These can include factors such as: 

• Particle size—For extremely fine matter, the design might feature a high inlet baghouse, with the baghouse inlet located on top of the unit rather than through the hopper.  
• Moisture level—This would include moisture level in the material itself or the relative humidity of the plant or processing environment. Special design features can accommodate moisture levels, or oily material/dust collection.  
• Abrasiveness—Highly abrasive materials might call for special design features such as an abrasive inlet or guards on the bags, prevent bag erosion. 

Regulatory Requirements—All SLY systems are designed to help facilities comply with federal and local regulatory bodies. Access platforms and ladders are designed to OSHA specifications.  

Environment—Any baghouse design should take into consideration environmental factors related to its location, such as wind loading, snow loads, live loads and seismic loading (earthquake).  

Media Selection for Bag House Filters 

The number of filter bags and the type of material used for the filter bag is dependent upon the objectives for dust capture and local or state regulations. Some bag media or materials can achieve higher particulate removal than others. This choice of bag media is determined by the following factors: 

• The characteristics of the particulate that requires capture (i.e. particle size distribution, abrasives, moisture, followability, etc.)   
• Required emission rates
• Gas characteristics (i.e. gas composition, operating temperature, humidity, etc) 

In facilities with more stringent emissions policies, bag options can include a tighter weave or membranes to achieve greater filtration. Emission allowances vary from one locale and in the U.S., from one state to another. For example, California has stricter emissions policies than some other states.   

Properly Installed Filter Bags Close the Gap 

Typically, the customer’s contractor or construction firm will install filter bags into a new baghouse. The bags must be installed with the proper sealing method, otherwise the dust particles will bypass the bags. In addition, improper installation practices can rip or tear the bags, which also would decrease or void their dust collecting capacity.  

Depending on system design, filter bags are either top-loaded or bottom-loaded. Bottom-loaded bags must have properly tightened clamps to eliminate any gaps. Top-loaded bags have a band at the base which must seal against the tube sheet.  

Various signs that indicate improper bag installation: 

• Loose seal against the tube sheet (the point where the bags connect to the system) 
• Bags that turn easily 
• Loose clamps (on bottom-loaded bags) 

Scheduled Maintenance Helps Determine Bag Replacement 

While a pulse system baghouse offers years of reliable operations, the bags themselves, or the filters, will need eventual replacement. An optimized controller that cleans the bags to the right degree and on a regular cycle helps minimize the amount of cleaning cycles, which results in lower compressed air usage, reduced filter wear and lower operating differential pressures to reduce energy consumption. 

The controller determines bag cleaning cycle, which is commonly based on a timed cycle or pressure drop. When the pressure drop reaches a preset pressure, it automatically initiates a pulse or cleaning cycle. This pressure drop offers a key indicator for bag replacement. A change in pressure drop outside of the norm indicates the bags are starting to “blind” or become so loaded with dust they can no longer be cleaned effectively and must be replaced.  Higher than optimal system differential pressure results in higher operating costs. 

Cleaning the bags to the right degree means not pulsing or cycling too frequently. Each bag should retain a certain amount of caked up dust, because this helps with the filtration. An experienced baghouse operator knows a bit of caked dust on the bags aids with system efficiency.  

As a general rule, a bag inspection is recommended once per year. If the dust or particles collected are more abrasive, this could translate into a more frequent bag inspection. Bag changes are easy with a SLY LLC “no tools required” design. 

Components and Services that Complement Baghouse Functions  

For baghouses that are used for nuisance dust collection, it is important to have a properly designed industrial ventilation system to effectively vent the material from the work area to the baghouse. Typically, a fan pulls air through a specially designed hood via the duct work to the baghouse. The fan needs to provide enough flow and suction to capture all the dust generated through processing.  An adequate flow keeps the air and particulate moving through the duct work dust collection.  

The use of energy efficient motor (EEM) can be used as a tool to reduce operating coat of the system. An EEM is a motor that gives you the same output strength by consuming lesser amounts of power. This motor doesn’t necessarily impact dust collection efficiencies; however, it can help with overall operational costs for energy expenditure.  

As part of SLY startup services, customers can take advantage of commissioning, that starts up and tests equipment for proper bag installation. SLY also provides operator training for operations, care and maintenance of the baghouse and dust collection system.  

Protect your workforce and workplace, avoid high emissions and maintain plant productivity with an engineered dust collection system from SLY, LLC.  

Questions about improving the efficiency of your dust collection system? Our engineers are available to help determine the specifications for an efficient baghouse system for your processing environment.