Over the last several decades, mechanical dust collectors have evolved from air pollution control devices into a reliable, low-maintenance means of erosion protection for downstream system equipment. They are an increasingly important part of your steel mill’s air handling systems.
The Evolution of Mechanical Dust Collectors
For over 60 years, mechanical dust collectors have been used with biomass-fired boilers to extend the operational life of induced draft (ID) fans and pollution control equipment by removing ash and sand particles.
In the 1950s, the first generation of mechanical dust collectors, known as the STD (standard or limited access) design, began being installed in large numbers. This design was characterized by a sloped top tube sheet, close spacing between tube assemblies, and varied outlet tube lengths. This design was only effective when the tube row depth was limited, as applications with excessive depth could lead to unbalanced gas distribution.
The second generation of mechanical dust collectors, known as the AU (totally accessible unit) mechanical dust collectors, was introduced several years later. These dust collectors had hoods over uniform-length outlet tubes and alleyways between groups of tubes.
The older STD design didn’t accommodate inspections or part replacement without an extensive, labor-intensive rebuilding effort, but the updated AU design had space for a technician to perform required cleaning and maintenance services. It also enabled a more balanced gas distribution, which significantly impacts performance on deep dust collectors.
Benefits of Larger Inlet Tubes
Earlier versions of mechanical dust collectors used small diameter inlet tubes (6″), believing smaller tubes create greater centrifugal force, causing more particulate to be separated from the airstream, but most manufacturers offered several tube sizes. Nine and ten-inch tubes became the most popular and most used for biomass-fired boiler applications. Many manufacturers and users felt that these tubes struck the perfect balance between air volume handling ability and collection efficiency.
Many designs called for nine and ten-inch, even in medium to large-size boilers that required mechanical dust collectors to handle huge flue gas volumes (100,000 acfm and greater). Performance on these designs dropped significantly over time.
Testing and analysis concluded that using fewer, larger tubes made it easier for all of the tubes to work equally hard, providing better overall efficiency. These larger tubes handled more flue gas, reducing the total number of tubes required and opening up passages between tubes.
These insights led to the creation of the current generation of mechanical dust collectors, known as the AU24″ design. This design was introduced in the early 1990s and combined total accessibility and larger 24″ diameter tubes. The current generation of mechanical dust collectors provides improved performance and a longer operational life.
ProcessBarron offers four different mechanical dust collector inlet tube sizes: 9″, 11.5″, 14″, and 24″, including totally accessible (AU) and limited access (STD) mechanical dust collector arrangements. See our dust collector tubes here.
Mechanical Dust Collector Maintenance Services
Our experts have been designing, engineering, fabricating, and installing dust collectors for over 40 years. We know the ins and outs of this equipment and understand that the right solution for your plant will be unique to your industry, needs, and budget.