Spinning Again

Most startups are installing new machines, but purchasing second-hand decanter centrifuges is a technology sacrifice some ethanol producers are willing to shoulder. Several U.S. dealers and brokers offer a variety of used and reconditioned decanter centrifuges. EPM explores the pros and cons of this option.
By Tom Bryan | August 01, 2003
Machine Description:
A decanter centrifuge, or horizontal solid-bowl centrifuge, is a mechanism used to dewater spent grains. A decanter is one type of centrifuge among perhaps 30 or more manufactured worldwide. The machine's function is to separate - or literally decant - liquids from solids in the ethanol-making process. A typical 40-mmgy ethanol plant would install four, sometimes five, decanters.

Sharples, a company purchased by Alfa Laval several years ago, arguably supplied more decanters to first-generation U.S. ethanol plants than any other manufacturer of the era. In fact, many of the used and reconditioned decanters available today are Sharples machines. Known for lasting durability - but not necessarily great efficiency by modern standards - it is not uncommon to find robust Sharples decanters in use today that were originally manufactured in the early 1970s.

The Leading OEMs:
While several international companies manufacture new decanter centrifuges, the U.S. ethanol industry is supplied principally by three original equipment manufacturers, or OEMs: Westfalia Separator, Inc., with sales offices in Northvale, N.J., Alfa Laval, with sales offices in both Oak Brook, Ill., and Richmond, Va., and Flottweg Separation Technology, of Florence, Ky.

Used, Reconditioned Sales & Service:

The decanter aftermarket is made up of several small companies that sell used and reconditioned machines and also service existing machines for producers.

Bensenville, Ill.-based Aaron Equipment, a third-generation family-owned business, is one of the largest dealers of new, used and reconditioned process equipment in the world and the largest international dealer of used and reconditioned centrifuges. Aaron Equipment has been selling used centrifuges, dryers, evaporators, stand-by generators, seed tanks, fermentation tanks and other process equipment to the ethanol industry since the early 1980s.

Over the last decade, Aaron Equipment has supplied many of the used and reconditioned Sharples centrifuges used in the ethanol industry today. The company remains concentrated on supplying used and reconditioned Sharples centrifuges with "state-of-the-art, new drive and control systems" that meet industry standards. In addition, the company has been involved in selling surplus parts and equipment from ethanol plants.

Roemer Machine of Davenport, Iowa, is a service provider that ordinarily rebuilds decanters purchased from Aaron Equipment's inventory. Roemer Machine is arguably the ethanol industry's most experienced decanter reconditioning and rebuilding service provider, with 34 years in the business. Producers say the company has impeccable quality standards and has earned one of the best reputations for machine repair in the ethanol industry. In fact, some of the repair procedures and specifications the company pioneered are today's industry standards.

"Service is the name of our game," Roemer Machine shop supervisor Carl Stark told EPM. "About 70 percent of our business is in the ethanol industry."

Jenkins Centrifuge, of North Kansas City, Mo., is a broker and small OEM that offers ethanol producers reconditioned decanters, as well as decanter rebuilding and repair services. Owner Doc Jenkins has a team of 27 employees primarily dedicated to rebuilding decanters. However, due to demands from its customers, Jenkins Centrifuge began manufacturing its own make of decanters (largely for the meat-packing and rendering industry) in 1990. Jenkins told EPM his company sells about four or five new decanters a year.

In addition, Kyte Centrifuge Sales & Consulting (KCS & C), of New Bern, N.C. is a small broker that offers the ethanol industry used and reconditioned decanters and decanter parts. KCS & C, operated by Ken Kyte, sells reconditioned centrifuges and offers testing services, process recommendations, troubleshooting, inspections, reconditioning assistance, parts location assistance, appraisals and centrifuge disposal.

Cost, Materials & Engineering:
While decanters are not particularly substantial in size, the machines are highly engineered and, as a result, quite expensive. Purchased new, the leading models range from $250,000 to $400,000 apiece, according to two industry sources.

According to Aaron Equipment owner Alan Cohen, decanter centrifuges, both new and used, are costly because an extensive amount of engineering goes into the equipment's design; the raw materials used to manufacture the equipment are very expensive (e.g., stainless steel centrifugal castings and carbide composite wear protection), and the manufacturing process entails a great deal of high-tolerance machining.

For this reason, Aaron Equipment, Roemer Centrifuge, Jenkins Centrifuge, KCS & C and other dealers source, supply and sometimes recondition used decanter centrifuges, offering models from the leading manufacturers at reduced costs, they told EPM.

Buying used decanters, while often considered a risk and a sacrifice on new technology, can save producers 20 to 40 percent - often more. For instance, Jenkins told EPM his company could remanufacture a used Sharples centrifuge for approximately $100,000.

Manufacturers' Claims:
Most dry-mill ethanol plants coming on line today are purchasing new decanter centrifuges, mainly from Alfa Laval, Westfalia and Flottweg. EPM learned that at least one dry mill that came on line in 2002 purchased multiple reconditioned decanters from a broker, but was considering replacing them with new decanters this year or next.

Cohen and Jenkins claim little or no operational difference between a new decanter centrifuge and a properly reconditioned machine. The disparity, they assert, is in price and time of delivery. They say a new decanter could take several months to build and deliver, while a remanufactured decanter could be ready in less than six weeks. Aaron Equipment currently has about 325 decanter centrifuges in stock and offers all the major manufacturers' models, Cohen told EPM.

However, the manufacturers contend, the turnaround time on a new centrifuge for an ethanol plant under construction is not problematic because it takes nearly a year to build the facility, giving the manufacturer several months to assemble and deliver the centrifuge.

More importantly, today's decanters are higher-speed, higher-integrity versions of the models manufactured two decades ago.

Higher speeds provide higher G-forces and greater separation efficiency, the OEMs said, and new decanters have built-in pumps for pressure discharge of the thin stillage, meaning there is no need for tanks, pumps or controls under the centrifuge. New decanters from Alfa Laval, Westfalia and Flottweg generally have lower motor horsepower requirements and a smaller footprint than old models. And there is evidence that new decanters provide cleaner thin stillage and drier wet cakes then the previous models, one OEM said.

"There's simply no comparison [of the new vs. the old]," a leading manufacturer's rep told EPM.

Furthermore, the manufacturers asserted, even though many reconditioned decanters are sold with warranties (Aaron and Jenkins both offer solid warranties), buying new typically comes with an assurance of having the latest technology and the best technical support structure available; these contracts typically include service and parts replacement guarantees and other advantages.

Disparity of Opinions:
As expected, companies that sell remanufactured decanters stand behind their machines whole-heartedly. Jenkins, for example, frankly told EPM, "There is no reason to ever scrap a centrifuge."

The major manufacturers - and apparently the leading ethanol plant builders - tend to disagree.

"Even when the machines are reconditioned, they are still used. It's very similar to buying a new car versus a used one," one sales representative said. "You can buy new parts, but you are still putting them into old, tired machines."

The OEMs also say new decanters run more efficiently and have lower operating costs.

Cohen said, the top ethanol plant builders use new centrifuges to trim down design time and also to transfer process guarantees to the OEMs. But that can be avoided, he said.

"If an ethanol plant knows its flow requirement, it can save a great deal on used or reconditioned centrifuges," Cohen said.

Indeed, manufacturers of new decanters will sometimes dabble in used equipment as well, but that usually means decanters that were used for a few years - or even as little as a few months - in a pilot plant or research setting. Companies selling used and reconditioned decanters will sometimes sell machines that are up to 20 or 30 years old, but offer newer models as well.

"Many of the centrifuges we provide are unused or have only been in service a short time," said Whitney Craig of Aaron Equipment.

Interestingly, the OEMs and used dealers both provide service support and parts for reconditioned centrifuges used in the ethanol industry. They generally provided new drive and control systems with full mechanical warranties on the centrifuges themselves.

Manufacturers say their equipment is built to last about two decades. While the conceptual design of decanters has not changed much over the last 20 years, the systems built today are computerized. According to the manufacturers, that means getting parts for used models sometimes entails obtaining hard-to-find drawings and parts that are in short supply, and also custom-modifying machines.

Find out more about used and reconditioned decanter centrifuges at Aaron Equipment's Web site, www.aaronequipment.com; Roemer Machine at www.roemermachine.com; KCS & C at www.kcentrifuge.com; and Jenkins Centrifuge at www.jenkinscentrifuge.com.

Listings for the Alfa Laval, Westfalia Seperator and Flottweg can be found on Page 80 of the 2003-2004 Fuel Ethanol Industry Directory. EP