Drag Conveyors for Ethanol Plants

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Ethanol plants have improved dramatically from their original designs. Plants making 40 million gallons per year are now pushing 70 million. Those making 100 million gallons can now produce 130 million. Yet, while producers have invested in optimizing their output, they’ve relied mainly on the same conveyance systems they used when their facilities were first built. These systems are thus often pushed past the capacities for which they were designed and experience accelerated wear, straining maintenance personnel. But wear isn’t the only shortcoming of these systems. They’ve experienced other issues from the start, like poor humidity control, difficult maintenance, and dust spillage.

Operations managers would do well to address these challenges, and they’d undoubtedly like to do so. But what’s their recourse? What else is available besides the single-chain drag conveyors, screws, bucket elevators, and pneumatic conveyance systems they’ve always used?

The answer is SMART Conveyors™ from BE&E.

BE&E Drag Chain Conveyors

BE&E’s drag conveyors are the SMART choice for handling materials in both front- and back-end processes at ethanol plants. Corn, flour, wet cake, DDGS—SMART Conveyors™ can handle these materials more efficiently with less maintenance, dust spillage, and humidity infiltration than alternatives.

That’s quite the claim. But it’s one we’ll back up, as our customers attest.

Let’s walk through the processes at an ethanol plant that involve handling bulk materials and compare what operations typically use with BE&E’s SMART Conveyors™.

Corn Receiving

Ethanol plants use drag or screw conveyors to receive kernels. Of primary concern in these systems are their reliability and ability to withstand wear. The receiving system must perform without fail, which maintenance crews work relentlessly to achieve. The risk that something may go down is always on their minds because they know how finicky the conveyors can be. Agricultural-grade conveyors aren’t known for reliability.

SMART Conveyors™, however, are designed for continuous operation in conditions that routinely chew through agricultural-grade conveyors (as our customers have experienced). To this end, we’ve equipped them with paddles and frames meant to withstand a beating. The paddles are uniquely designed with “fingers”—cuts that allow them to flex when they encounter an obstruction. This feature protects the chains and shafts from damaging stress and helps prevent amperage spikes if an object wedges beneath the paddle.

The paddle frames are designed to prevent damage, as well. SMART Conveyors™ are a twin-chain system, so they hold the paddles on both sides. Thus, when a paddle encounters more stress than a finger can absorb, it bends into a scoop shape. This deformation stands in stark contracts to single-chain conveyors, the paddles of which all bend backward when they encounter loads too much for them to handle.

There are still more controlled fail points in our design. If the stress increases, the paddles will roll. And if that’s not enough (we’re talking about a considerable obstruction now), the pins connecting them to the chain will break.

With this design, SMART Conveyors™ have survived some severe damage when obstructions have formed or oversized objects have entered the material stream. Paddles have broken. Things have gotten wonky. But the conveyors have run despite damage.

Corn Milling

After having been received and stored, corn is transferred from the silos to the hammermills. To move it, ethanol plants again employ screws, belts or drag conveyors.

Besides reliability, moisture is a concern at this stage. When the flour gets exposed to humidity or rainwater, it becomes sticky and clings to the conveyors. Over time, the flour can build up to the point where it restricts flow and causes the material to back up into the transfer systems earlier in the process.

While BE&E’s SMART Conveyors™ aren’t airtight, we can seal them up better than the conveyors with clamp-on panels many ethanol plants employ. Our production team can easily seal our conveyors with gaskets to prevent rainwater and limit humid air from entering the box.

Besides moisture control, SMART Conveyors™ offer other advantages in front-end bulk handling. One, they require no hanger bearings as screw augers do. Hanger bearings are notorious for their brief service life, so they are unpopular with maintenance teams. If the bearings last between the service periods, crews religiously replace them the plant shuts down for maintenance twice a year. Waiting longer to replace them has proven impossible.

Two, SMART Conveyors™ don’t leak dust. They’re fully enclosed, meaning they contain dust inside the box. What’s more, we’ve tested them to ensure they can withstand the overpressure of an explosion when equipped with blast vents. Unlike other suppliers, we haven’t just relied on computer models to confirm whether our conveyors are as robust as we believe they are. We’ve proven it.

Dust is a safety issue, and it doesn’t take long for it to pile up to the ¼” limit on surfaces around the conveyors. Unfortunately, crews often fall behind in cleaning it up. This failure puts the entire plant at risk for primary and secondary deflagration events, which have become more common as plants have increased their production rates.

Handling Wet Cake and DDGS

SMART Conveyors™ are also excellent choices for handling spent grains, both wet and dry.

Pneumatic conveyance systems were popular for handling DDGS in early plant designs because engineering firms could easily reroute them to fit any plant’s layout. However, this conveyance method has posed several problems.

The first is the power they consume. Pneumatic conveyance systems are by nature inefficient. Most of their energy goes into moving air rather than the material. 600-hp blowers aren’t unheard of. The second issue with them is that they plug when the material’s moisture level suddenly changes—if the operators forget to switch the pneumatic system to “wet mode,” the DDGS quickly pack the pipe.

Fluctuations in moisture are also problematic for the drag conveyors plants commonly use. When the dryer system goes down, conveyors designed to handle DDGS are suddenly flooded with heavy, wet material, which bends the paddles. Whenever this happens, maintenance technicians must afterward spend hours bending back the paddles into their proper alignment so they can function again.

Chain conveyors also receive damage from other objects that make it into the material stream, such as broken dryer fins. And replacing the chains in these conveyors is a hassle. It’s so difficult that some mills don’t bother doing it themselves. They pay outside millwrights to perform the service.

SMART Conveyors™

All these issues SMART Conveyors™ can address. They’re up to 25 times more efficient than pneumatic systems in the same application. They also commonly require half the horsepower as competitors’ drag systems. They’re so efficient that one of our most frequently asked questions is, “Really?” People don’t believe our conveyors need so little horsepower.

But it’s true. Because the chains hold the paddles on their sides, we can keep them from touching the floors and sidewalls. We also run our chains outside the material path in UHMW-lined channels. The only steel-on-steel friction occurs at the sprocket.

There’s also no need for operators to switch modes when the material suddenly changes. As long as we plan for variances up front, the conveyor will always have enough capacity to take on extra weight; unplanned shutdowns needn’t occur.

SMART Conveyors™ have much to offer the ethanol industry—reliability, safety, energy efficiency, and they’ve proven themselves in hundreds of installations across North America. Are you ready for them to prove their worth at yours?

Contact us now to start a discussion!