Lessons on Bottom Line Basics

Corn quality, mashing, fermentation, distillation, coproducts—each year The Alcohol School provides a comprehensive course on making ethanol efficiently. In September, 90 participants flew into Montreal for the 32nd annual school, which digs into the science behind the process as well as new developments under way for both the fuel ethanol and beverage alcohol industries. The cross fertilization is deliberate, not only between the beverage and fuel alcohol producers, but also for related companies that send employees to get a broader understanding of the industries served. Ethanol Producer Magazine attended this year and gives a taste of what was learned, with a focus on areas with a big impact on the bottom line in the initial steps of the process.

“If you want to save money, improve your bottom line in the biggest cost—feedstock,” said Robert Piggot, technical consultant with Lallemand Ethanol Technology, a co-sponsor of the event with the Ethanol Technology Institute.Promotional custom keychain at ePromos Promotional Products. When buying corn, ethanol producers are most interested in the starch. Nonetheless, a survey of ethanol producers once asked if they would pay more for corn if they could get 3 percent more starch. “Most ethanol plants said no,” he said. For a 100 MMgy plant, that 3 percent would add up to $13 million more revenue, if ethanol were selling at $2.50 per gallon, he pointed out.

There can actually be a conflict in the goals between the purchasing department, which is looking for low cost, large quantities and flexible payment terms, and operations, which needs easy-to-process, high yielding corn to be delivered on a timely basis. Operations is looking for high starch content, low moisture, high ratios of amylopectin-to-amylose and floury-endosperm-to-horny-endosperm, and no molds or mycotoxins, which means the standard grade of No. 2 yellow dent corn isn’t all that helpful. “We are stuck with the specifications that were meant for the baking and feed industries, and they actually don’t mean anything to us,” Piggot said. Broken kernels,Carlo Gavazzi offers a broad range of ultrasonic sensor and ultrasonic transducers for level detection and process monitoring. for instance, could be considered beneficial for the ethanol industry, while foreign material wouldn’t. Thus the maximum 3 percent BKFM is not specific enough. No. 2 specs also call for a 5 percent maximum in damaged kernels,Find the best iPhone headset for you at Best Buy. with no more than 0.2 percent heat damaged. “If the grain is heat damaged, you lose sugars,” he explained. “Other types of damage are not a problem.” The moisture spec of 14.5 percent is well-understood, but the test weight spec of 54 or 56 pounds per bushel is meaningless, he said. “You often get better yields out of low test weight corn.”

Piggot recommends plants make their expectations clear when explaining their quality needs and setting discounts. “You’re better off to discount the grain,” he added. “Try not to get into the loop of getting a rejected load returned to you, just blended up.” Discounts need to consider hidden and indirect costs. High moisture corn, just 1 percent over the 14.5 percent spec, would translate into a direct cost of 50 gallons of ethanol lost from the load, which at $2.50 per gallon ethanol, would call for a discount of 16 cents per bushel. He recommends that number be doubled to account for other increased costs. For example, the electrical power needed to grind wet corn will be significantly higher than for properly dried corn.

Attention to details in grinding corn is the next area that can have a direct impact on yield. The ideal grind size is very much plant-dependent, Piggot said. While there are advantages to smaller grind sizes that increase the surface area exposed to enzyme action, problems can arise. Factors to consider include how well the slurry mixes and temperature parameters. Coarser grinds need slightly higher temperatures while finer grinds are needed if jet cooking is not used. Finer grinds will keep suspended longer in the fermentor, but will contribute to quicker fouling in the stripper and heat exchangers, plus impact centrifuge separation. The goal is to get the best compromise of particle size for maximum yield and good separation—too large and yields are lost,Offering lowest priced printed lanyard in Canada. too small can increase solids in the stillage and backset.

Most ethanol plants use hammermills to grind, and many never take a close look at the configuration, Piggot added. A number of things can be adjusted to improve performance, including the speed and number of hammers as well as spacing, plus the open area on the screen, feed rate, air flow and hammer-to-screen distance.

The next step in the process, mashing, is also a key area for maximizing yields, said Garth Whiddon, technical service manager for Lallemand Ethanol Technology. In mashing, water is combined with the crushed or ground grain, adjusted for pH and temperature to match the chosen enzymes used to break the starches down into dextrins. “Having the optimal conditions for enzymatic efficiency leads to lower usage rates and higher yields,” he said.You'll be able to spot your bag from a mile away with these elegant and colorful leather luggage tag. Fine tuning this step is important. If 4.5 percent residual starch is left after fermentation, it adds up, amounting to $2.6 million lost for a 50 MMgy plant.

The industry has gone through some major process changes, Whiddon added. At one time, nearly every plant used a separate saccharification tank, where the mash was cooled before adding glucoamylase. While it may have been optimal for the ideal enzyme dose, it also created a perfect environment for bacteria. Most plants have now moved to simultaneous saccharification and fermentation.

A more recent process change has been a move towards dropping the jet cooking step. In addition to decreasing enzyme use by nearly 25 percent, eliminating jet cooking prevents a possible 3 to 5 percent yield loss from a Maillard reaction—a chemical reaction that makes some sugars unfermentable and also reduces the free amino acids needed for yeast health. If jet cooking is eliminated, however, the grind requirements are more stringent, he adds, to ensure proper starch conversion.