Biting the Bullet on Major Replacements

FROM THE APRIL ISSUE: Ten-year inspections, and sometimes outright failures, focus attention on needed capital investments in long-term assets.
By Susanne Retka Schill | March 20, 2018

The ethanol industry is small enough that word travels fast. “I believe something happened about three years ago, some failures started happening because all of a sudden my phone started blowing up from the ethanol industry,” recalls Mike Ferguson, president of Eddy Current USA. His specialty is nondestructive testing to find scaling and pitting in difficult-to-inspect tubing in condensers, heat exchangers and chillers.

The biggest issue he’s seen at ethanol plants is with the 190 condenser—the system that concentrates raw ethanol vapors into liquid. He’s known of some failures, and found early indications at other plants he’s monitoring after taking baseline readings. “We can follow the problem so it doesn’t become a catastrophic failure,” he says. “There’s a good probability of protection and life extension.” And it buys a little time to budget for retubing or replacement.

“I don’t think it’s the age of the facility or the equipment that dictates the degradation,” he continues. “I believe it’s mostly a factor of process controls and how hard they’re run and how good the maintenance program is. With the 190s, a lot of what I see is because of running the machine really hard.” He adds that from his decades of experience in the chiller industry, it is helpful to do testing even when equipment is new. “My records show almost 20 percent of tubes had original defects in the tube from the manufacturer.”

Ferguson compares the ethanol industry today to what he was seeing in the chiller industry 30 years ago, when it was cheaper to deal with freon leaks than to invest in testing or replacing the components at the root cause. Often, the result for the large industrial and commercial air conditioning systems was catastrophic failure. Today, he says, “everybody knows what to do. Now that the chiller industry has caught up and is aware, there is minimal catastrophe.”

As manager of reliability services for ICM Inc., James Weber concurs with Ferguson’s observation that there’s no direct correlation between the age of a plant and what is found during inspections. “We’ve seen equipment at 12-year-old plants that looks brand new.”  And, he adds, some inspections find a potential failure just weeks away, creating a big problem. “You never find out about it until the middle of a shutdown, and it could prevent you from starting up on time.”

Many places doing 10-year inspections are opening up areas that haven’t been looked at since start-up, Weber says. In some cases, better maintenance could have prevented issues, and in others, new protection measures or better technologies are available. There were early indicators of some issues, he adds, showing up as minor problems. “Standing back, asking why and looking at the root did not seem to happen as much as it should.”

Weber shares his list of issues seen as plants age. The 190 condensers in distillation are on his list. Many plants are finding tube failures exceeding the 15 to 20 percent allowable tolerance, he says. “So they’re going in and replacing those. And it’s the same with sieve vaporizers—we’re seeing tube failures there. What it’s actually from, whether it’s water quality or vibration, we don’t know yet. But we’re seeing plants looking at replacement options.”

Another area seeing tube failures is in the economizers at those plants with thermal oxidizers, he says. “That, again, is a costly problem, but there are solutions in place and they can install newer and better ones, with better materials and better designs.”

Internal inspections of sieve bottles, another 10-year requirement, are finding some cracking, he continues. “These are mostly repairable, but it is something people should be aware of.” Again, the root cause hasn’t been determined yet, he says. “It could be in the manufacturing of the vessel, it could be excessive vibration.”

Pipes and Tanks
The miles of piping and rows of tanks circulating material through an ethanol plant also are among the long-term assets showing signs of wear at many facilities. Slurry tanks, in particular, are starting to show fatigue, Weber says. “The original steam system in a lot of these slurry tanks causes a lot of vibration. There’s better equipment available today that reduces that vibration and a lot of people have done upgrades to extend the life of the tank.” Ethanol storage tanks also are on the 10-year inspection list, and some plants are finding holes or pitting of the floors. “There’s systems that can be installed that help reduce that,” Weber says.

Clean in place (CIP) piping is showing wear in plants that were designed with carbon steel piping. It can perform well over time, Weber explains, as long as the process is maintained correctly, but in places where there was excessive heat or poorly controlled chemical dosing, the CIP pipes may need replacement. “There are plants starting to change out to stainless steel,” Weber says. “The problem is, it’s a lot of piping—it runs all through the plant.” One strategy is to replace small chunks at a time during regularly scheduled shutdowns.

Another system showing corrosion is in the gas-train piping, he says, primarily because of condensation. “It’s a hot environment and you have cold gas coming through, so you get condensation on the lines,” Weber explains. Again, there are protection solutions that can be employed.

Two systems originating in the grains building also are on his list. “In the last couple of years, we find conveyors that haven’t been well-maintained to the point where it’s full replacement.” Not a critical system, conveyors can get overlooked, he says. “It seems to be doing fine, it’s not making noise, no bearings smell like they’re burning, so they just keep on running it.” He recommends annual inspections with the covers pulled off to check bearings and seals, making sure bolt holes aren’t getting egg shaped and causing extra movement.

The bag houses filtering dust from moving grain and distillers may not have a lot of moving parts, but they are another long-term asset showing wear in some situations. “Just in the last year, we’ve seen corrosion on the inside,” Weber says. “People are having to patch the skin and look at replacement.” A lot of that, he says, is a result of conveying higher moisture DDGS in pneumatic systems.

Maturing Approach
As he stands back to think about his list of big-ticket replacement and repair items, Weber says it’s partly a function of the rapid expansion of the industry in the mid-2000s when so many plants were operating with all-new equipment and so many maintenance teams were new to ethanol plants, and often to industrial maintenance altogether. In some cases, a farmer mentality prevailed, he says. “You fix it when it’s broken and if you can tape it back together to run another six months, you tape it back together. That doesn’t necessarily work in a facility of this size, especially with what you’re trying to do with it.”

It’s come a long way, he adds. “I think everyone at the plants, from maintenance guys up through the board members are starting to understand what is truly the maintenance cost and how much money they need to set aside for capital improvements or general maintenance of larger pieces of equipment,” he says. “Just the equipment alone is $100,000-plus, which is a hard pill to swallow. But knowing they got 10 years of life out of the original piece helps. And they’re all starting to understand they’re not the only ones having to do this higher dollar maintenance and replacement.”

Making that major capital expenditure is not an easy decision. Bob Jewell, energy systems chief at Chippewa Valley Ethanol Co., recalls the plant’s experience before replacing the cooling tower at the 20-year mark. “We realized the issue long before we replaced the cooling tower—but that was several million dollars versus a couple hundred thousand to replace a condenser.” The plant was also replacing heat exchangers. “Those failures were directly related to the cooling tower,” he says. “After we bit that bullet and replaced the cooling tower, it was really an eye opener.” In addition to solving the cooling system issues, he says, “We experienced quite an increase in production.”

Jewell recommends the ethanol industry leverage the experience of others—not just among ethanol peers, but outside, pointing to his area in the energy sector. “The power production industry is relatively old and they’ve learned a lot of lessons. Some of that experience is transferrable to us.”

Author: Susanne Retka Schill
Freelance journalist