Bulk materials handling is a term used for the transport and storage of various types of materials. This could be anything from aggregate products such as rock or powders to biomass based products such as grains, wood chips, bark etc. At ProcessBarron our expertise centers around the industrial market where we design material handling systems for boilers, kilns, and furnaces. In a recent conversation, our resident expert in material handling, Joe Waite, explained the different aspects of conveying systems to increase efficiency and minimize plant downtime.
What is a Mechanical Ash Handling System?
A Mechanical Ash Handling System (MAHS) is commonly used to collect, transport, and store fly and bottom ash from industrial boilers utilizing biomass as a fuel. These systems typically utilize drag chain conveyors, screw conveyors, and storage silos. Unlike pneumatic systems which rely on air as the transport media, mechanical ash systems offer distinct advantages in terms of safety and reliability. Oftentimes the fly ash collected, especially in biomass boilers, may include unburned fuel.
The mechanical system which does not introduce ambient air like a pneumatic system presents a lower fire risk due to the absence of oxygen. Mechanical systems are also more robust and typically use less energy than a pneumatic system.
Key Fuel Types in Mechanical Conveying
The most complex aspect of a biomass fuel handling system is typically at the feed end, where variability in incoming materials poses significant challenges. While the output material, post-combustion or after processing, is generally similar in size and composition, the input fuxel can vary, especially with bark and biomass. Engineering specifications for new boiler systems often call for fuel that is clean and sized at 2 inches or less.
However, once a facility is operational, cost considerations can drive purchasing decisions, leading to the use of cheaper, off-spec material, sometimes much bigger in size or containing a high percentage of dirt and contaminants. For example, following major storm events like hurricanes in the Southeast, facilities may source large volumes of storm debris as fuel. While this is a cost-saving solution, the material is often inconsistent and outside the design specifications of the boiler.
Recognizing this reality, ProcessBarron designs and engineers conveyors with built-in overcapacity and durability to accommodate a wide range of fuel qualities, ensuring the system remains reliable even when handling suboptimal or contaminated fuel.
If you drive in rural parts of the country, you’ll see chicken houses, long buildings with fans on the wall. You’ve probably seen them before.
Each time farmers grow a new stock, they have straw litter on the ground, and that’s what absorbs the feces from the chickens. In the past, every time farmers cleaned out the chicken houses, they were taking the material, and disposing of it in a landfill. Fast forward to today, we have found an alternative that isn’t as wasteful. Instead of throwing it into a landfill, we burn the contaminated straw in an incinerator and turn it into steam, and a boiler then generates power with it.
Not only are we repurposing the material, but we’re also generating power from it—a zero-waste solution.
For example, if we are dealing with lime, it’s very caustic, and when it mixes with moisture, it can burn you, which is important to know in advance. If we’re dealing with fly ash, which has high amounts of Carbon in it, the material can potentially catch on fire. From a safety perspective, this is a crucial part of the conversation.
Another example is if we are working with bottom ash that is wet, we know that there are not many hazards with that. It’s just a matter of figuring out the best way to convey it. When handling bark, there are typically no hazards. It could be cottonseed, it could be plastics, or it could be pellets for a wood mill. All of the different fuel types play a part in recommending and designing the right equipment for material handling.
In the last 20 years, Waite has created a technical library that shows the different products ProcessBarron has incorporated in material handling applications. These are the specimens he collected from different customers to help the team determine the best conveying solution.
Biomass
Biomass can come in many different forms ranging from clean wood chips all the way to very poor quality fuel stocks such as bark and forest debris. The most challenging can be the typical fuel stocks like bark which can vary widely in size, moisture content and often contain lots of foreign debris such as dirt and silica. Designing and supplying the right equipment for these challenges is what Process specializes in doing.
Alternative Fuels
Wood is oftentimes not the only fuel used. Tire Derived Fuel (TDF), Municipal Waste, Plastics, Sludge, Saw Dust, and even garbage are sometimes used as fuel as well. Sometimes they are used as a stand alone fuel but often are used in conjunction with other fuels such as bark. All of them have their own unique challenges
Choosing the Right Conveyor for Each Fuel
Selecting the right equipment for conveying your materials is not a one-size fits all approach. Our skilled team members are on call to help guide and support you through the process.
Here are our select conveyors and their uses.
Drag Chain Conveyors
Drag chain conveyors are specifically engineered for vertical material handling applications, capable of transporting bulk materials such as coal, wood, tire-derived fuel (TDF), lime, and other flowable solids while minimizing degradation and preserving particle integrity. ProcessBarron’s engineers can design fully customized drag conveyor systems with multiple feed (inlet) and discharge points. These configurations are optimized based on material characteristics, required throughput, and spatial constraints to ensure efficient, continuous operation and seamless integration into existing process systems.
Screw Conveyors
Screw conveyors are highly adaptable design options, supporting multiple inlet and discharge points to suit complex material handling requirements. Standard, off-the-shelf systems often fail when it comes to the specific needs of industrial operations. We custom-engineer screw conveyor systems using high-strength, abrasion-resistant steels and specialty alloys to ensure durability in the harshest environments. Our conveying systems are designed to efficiently move free-flowing and non-free-flowing dry or semi-dry bulk materials, making them ideal for demanding applications in the biomass, cement, and steel industries. Whether handling wood waste, kiln dust, or mill scale, we tailor each solution to optimize performance, reliability, and plant integration.
Belt Conveyors
Belt conveyor systems are best suited for dry materials, as damp or sticky substances can cause clogs and make cleaning difficult. For hot, sticky, or corrosive materials, screw or drag chain conveyors are more effective. Typically, belt conveyors are simple systems with a belt, platform, and pulley, but they are not ideal for wet or corrosive products, which can damage the belt. Depending on needs, they can operate alone or alongside other conveyors in a more complex system.
Comparison of Conveyors
Our Process
Whenever ProcessBarron is replacing a piece of equipment or learning about it, we want to have a material spec from the customer. This is the first step in the process.
“We need to know exactly what we’re conveying, the density and the flow rate. A lot of times, what we’ll do is ask the customer to send us, say, a five-gallon bucket of the material that we can physically look at and test. This helps our team understand what we’re moving, but we’ve encountered so many different materials over the years that there isn’t much we haven’t seen,” explained Waite.
We recommend our customers perform regular maintenance on their conveyor systems, with a thorough inspection conducted during the plant’s annual shutdown, typically lasting a few weeks. During this time, maintenance teams should open all the lids and inspect key components. Because fly ash is abrasive, critical wear parts like slide rails, chains, and sprockets will wear down. Be sure to monitor wear patterns and identify potential equipment failures to avoid unnecessary downtime. ProcessBarron can assist you with the spare parts needed to keep your plant running 24/7/365.
Real-World Applications
Two biomass plants in Georgia were developed under the green energy initiative, taking advantage of government incentives and tax credits for burning biomass, which is classified as renewable fuel. The original plant design included a front-end dryer to reduce moisture content in the incoming fuel, primarily bark, debris, and waste wood, from approximately 50% down to 10%, aligning with the boiler’s combustion specifications.
However, the dryers never functioned as intended. As a result, the boilers, which were designed to burn dry fuel, were forced to process fuel with a significantly higher moisture content. This change drastically altered the combustion dynamics, requiring more airflow, longer residence time, and additional energy to evaporate moisture before ignition could occur. To cope, the plants were forced to reduce the boilers’ capacity and output, which directly impacted revenue.
Wet fuel also introduces material handling challenges. It tends to be heavier, stickier, and more prone to causing buildup in the system. On the back end, the ash handling systems, particularly the conveyors, are dealing with a higher volume of unburned or partially burned fuel due to incomplete combustion. Ash conveyors, originally sized for drier, fully combusted material, now experience excessive wear and frequent overloading. Components that were expected to last five years are now wearing out in a single year, leading to significant maintenance costs and operational downtime.
Adding to the risk, a substantial portion of the unburned wood resembles charcoal, still hot or even flaming as it exits the boiler. If oxygen is introduced into the ash conveyor system through leaks or poor seals, secondary fires can ignite. These fires are hot enough to damage steel components, warp conveyor flights, and even cause structural failure.
From an engineering and maintenance perspective, the fuel quality cannot be easily controlled without redesigning the boiler, an investment costing tens of millions of dollars. In the meantime, ProcessBarron works with the plant to reinforce and upgrade the existing equipment so it can withstand the harsher conditions.
It’s critical that plant operators keep the conveyors well-sealed and maintained while conducting repairs during scheduled outages. Failure to do so risks complete system failure. If ash cannot be removed, the boiler must be shut down, leading to production losses that can cost thousands or even millions of dollars.
Material Handling Challenges and Solutions
“Many of these projects develop while talking with customers. They have an issue, like bridging in a silo, conveyors backing up or materials not going down a chute. We’ve done this for so many years that we can look at something pretty quickly and go, okay, I think I know what your problem is. Your clearances are too tight. You’ve got the raw material on your screw flights. It needs to be wider. You’re going too fast. You need to make a better angle for that chute. We know how to make systems flow better. And like I said, it is learned knowledge over the many years of working in manufacturing,” said Waite.
Partner with Us
“I think as far as a company that can go into a plant, look at an existing system that’s running, and diagnose it, I don’t think there’s anybody else who can figure out the problems with the material handling system, mainly on the feed system, better than we can. We’ve got a lot of experienced salespeople. We’ve done so many of these projects. One of the biggest things about material handling is that it’s never an easy answer,” explained Waite.
ProcessBarron aims to increase efficiency and minimize maintenance. We have the conveyor parts you need ready and available for quick delivery and installation. We can provide multiple styles and sizes of drag chain for all your conveying requirements, as well as a wide selection of sprockets and hubs in stock, and have a full-service machine shop ready 24/7 for boring and machining. ProcessBarron handles everything better. Find a ProcessBarron sales representative today!