Disc Conveyors: Down the Tube

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Are disc conveyors (tubular conveyors) a good material handling solution for woodchips?

In short, no. Disc conveyors (a.k.a. tubular conveyors, tubular drag conveyors, tubular chain conveyors) do not handle woodchips well, especially in high volume or continual-use applications.

As manufacturers, we appreciate companies’ interest in expanding into industries outside their core clientele. We do the same—while wood processors make up the bulk of our customer base, we know our SMART Conveyors™ can handle many materials beyond wood waste. So, we constantly research new applications for our machines and network in industries that don’t process “biomass.” And we’ve had success in doing so. We’ve worked with DDGS in the ethanol industry, ground tires for a recycler, and birdseed for a feed producer.

But when we find an application in which our equipment doesn’t work well, we don’t pursue it. We have no desire to tarnish our reputation in failed efforts, and we want to save our customers the trouble.

However, some disc conveyor manufacturers market and sell their conveyors as adequate solutions for handling biomass despite repeated failures with the material. Again, we understand manufacturers’ desire to grow their businesses—we fault no one for that. Neither do we fault the attempt. But when there are so many examples of subpar performance, it’s time to draw a line and say, “Not this material.”

Still, we can’t assign motives. We don’t track what manufacturer installs its conveyors where, so as far as we know, separate companies have partaken in these failed attempts as they’ve tried individually to break into the biomass industry. But motives are beside the point. We’re writing to help you identify the best solution for handling biomass, not take shots at our competitors. Plus, ultimately, it’s up to you to determine the best machine for your material. No machine vendor can make you sign a purchase order.

So, why don’t disc conveyors handle biomass well? Friction and wear.

Disc conveyors have the same problem as the first iterations of our SMART Conveyors™, which we equipped with stiff, straight-edged paddles: material can wedge between the paddle and floor (or in the case of disc systems, the puck and the tube wall). When this occurs, the friction load on the system spikes and can cause failures in the chains, motor, or shafts. Such events are not uncommon in conveyors with enclosed chain paths: the system must release the energy somewhere, and it often damages the machine when it does so. (Read about how we address this issue in our SMART Conveyors™ with the paddle design and intentional fail points.) We hear about such events from customers that have utilized disc conveyors ­to transfer their biomass, with broken chains being a common complaint.

Wedging also contributes to wear. Biomass is not only frictional, but it’s abrasive. Thus, when it wedges under the puck, it scrapes away at the tube wall, especially in the curves. The wear invariably leads to high operational costs as maintenance technicians regularly replace or patch sections of the conveyors.

While we’re sure that disc conveyors generally work well for their core clientele—batch processors that handle materials with good flow characteristics—they do not work well for biomass. For such applications, we instead advise you consider our SMART Conveyors™. We designed our conveyors in and for the biomass industry and have hundreds of conveyors active in the field. Biomass is our core, and you can be sure we serve it well.

But why take my word for it? Contact us today to receive references and discuss how we might assist you in overcoming your material handling challenges.


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