Five Crucial Considerations for Biomass Material Handling Design

Mid-South Engineering’s Vice President Scott Stamey has more than 20 years of experience working with projects in the building products and biomass energy industries. Below, he highlights five critical design components when it comes to designing mat
By Biomass Magazine | February 02, 2022

1) Material Characteristics. “Understanding the characteristics of the biomass material you’re handling may seem like a no-brainer, but it’s the basis for all the other decisions you have to make with respect to how you’re going to handle the material,” Stamey says. “Moisture content can influence things like whether or not there are explosion or fire risks, and to what degree. Particle size and bulk density are important for deciding not only what type of conveyance you might use, but also in correctly sizing it, in terms volume to be handled and horsepower required.”

Material consistency should also be considered, as some pieces of equipment are more tolerant to a wide range, according to Stamey. “For example, bark—if it is always sized consistently, that makes things easy, but that’s uncommon. Equipment should be planned around that variation or to screen the material out. If there are seasonal differences, like the bark may come off differently in summer vs. winter, you must be able to accommodate both.”

Conveying equipment. “For conveying equipment, you will choose mechanical verses pneumatic,” Stamey says. “Mechanical is more common in biomass, as pneumatic does come with some downsides—it means fewer pieces of equipment, but typically it has a higher horsepower demand, as well as potential for safety risks like explosion and fire, and some environmental risks with emission points, which you may not have with mechanical.” There are many types of conveyors for mechanical handling, Stamey adds, and it’s important to choose the right fit for the material and the operation. “Additionally, conveying systems need good controls and automation to handle a range of operational conditions, and they should be easy to operate. I recommend an integrated supplier or independent engineering firm to put together the entire system to ensure it is designed properly and all components work together.”

Transition design. “Good transitions are critical,” Stamey emphasizes. “Most people realize that, but it can be overlooked. You want good transitions between different pieces of equipment that minimize damage to material and the transition itself. Along with this is optimizing loading, to ensure material is delivered into each piece of equipment correctly to minimize plugging, dust or other damage.”

Storage and reclaiming. Open verses closed storage have different capital costs—closed systems cost more, but pile storage typically has environmental and contamination risks, which doesn’t bode well for operations requiring a clean final product. “Determining the right amount of storage volume is usually an operational consideration or based on the delivery schedule of raw material,” Stamey says. Flow rates in and out of storage may be very high depending on the process, and first-in, first-out (FIFO) is an important factor. “Certain types of receiving systems will accommodate FIFO, but some don’t,” he says. “The amount of time the material is being stored should be considered.”

And, Stamey adds, whether the systems are automated or manual usually comes down to capital cost vs operational cost. “A highly automated system typically costs less to operate due to material handing efficiency, but it comes at much higher capital costs. However, there are ways to design manual systems that have lower capital costs, but the ability to add in automated systems later.”

Safety. “This is part of every decision we make when it comes to design, and some are minimum OSHA requirements like proper guarding on equipment and safety shutdown devices,” Stamey says.
“There are some minimums, but also recommendations that make systems safer, which an experienced equipment provider or design engineer can offer to the owner—for example, a plugged chute indication, which may not be included with the equipment itself, but can be engineered in.” Fire, spark and ember detection and suppression is critical with biomass, Stamey adds, as well as sprinklers and deluge systems. “Factory Mutual Approvals does offer some guidelines for that, and some insurers require FM compliance. They are a good resource for offering some guidance on what sprinklers and deluge systems are available for biomass handling systems.”