Because their products are made for human consumption, the brewery and pharmaceutical industries have utilized sophisticated clean-in-place systems with all the bells and whistles. The ethanol industry, on the other hand, isn’t subject to the same stringent regulations and therefore hasn’t traditionally paid as much attention to this vital but easily overlooked part of the process. “Ethanol is getting there,” says Troy Humphries, engineering director and owner of Tank Cleaning Technologies Inc., which offers Scanjet equipment and services. “In the last three years (the industry has) really learned a lot about CIP that they didn’t know when they first started to do this seven to 10 years ago. And that’s making a big difference.”
Looking back on the ethanol boom, the industry’s main focus was getting plants built as fast as possible. “It was a matter of get it online, get it producing ethanol as fast as you can—we’ll worry about efficiency later,” he says. Frankly, mistakes were made, including in the area of cleaning, Humphries says. For example, he estimates that 70 percent or more of plants built didn’t install cleaning filtration systems. “Most everybody is installing that now, or going to cleaning units that can handle the high solids level. That wasn’t considered very much when the plants were being built.”
Jeff Robert, president of Rendezvous Consulting Inc., agreed. “CIP was typically considered as an auxiliary system,” he says. “It was a system people recognize needed to be installed but it was not as well-defined as it probably should have been.” Like Humphries, he’s seen the industry investing in retrofits and upgrades of its CIP systems in the past three or four years.
In batch plants, the majority of dry grind ethanol plants in production, CIP kicks in after each batch, meaning a single fermentation tank would be cleaned approximately 120 times a year. The goal is twofold—prevent fouling and bacterial contamination. For most ethanol facilities, cleaning starts with a rinse, followed by pushing a hot water and about a 5 percent sodium-hydroxide solution through the system.
If the sodium hydroxide solution falls too far below 5 percent, the facility runs the risk of poor cleaning, which could lead to bacterial infections and lost yield, says Hans Alwin, business development director for Biofuels Automation. If it goes above 5 percent, it causes foaming, also reducing the effectiveness of the cleaning solution. It also costs some plants money in the form of anti-foam solutions injected into the blend tank. Both too much and too little sodium hydroxide can cause problems, but the biggest risk is bacterial infection. “Foaming is a nuisance,” Alwin says, “poor disinfections are financially hazardous.”
The fact that CIP solution can be reused is both a blessing and a challenge for ethanol plants. The dairy industry, for example, spends big money on CIP and water treatment because it is required to use new CIP solution at each cleaning, Alwin says. The ethanol industry, however, recirculates its CIP solution and it becomes more spent and less effective over time. Pete Fernholz, research fellow in Ecolab’s global CIP food and beverage division, describes it this way. As ethanol plant fermenters go through the CIP cycle, CO2 in the tank neutralizes sodium hydroxide, or the caustic soda solution, into sodium carbonate—a far inferior chemistry for cleaning. “You end up with a very long clean or a very poor clean,” he says.
Fighting Infection, Fouling
The potentially negative impact on yield is a big reason ethanol plants need to pay attention to their CIP systems and practices, says Jason Van’t Hul, industry technical consultant for the grain, oil seed and biofuel group of Nalco, an Ecolab company. He references something said by Mike Ingledew, past scientific director of The Alcohol School, in a story printed in the January issue of EPM. Ingledew calculated a year ago that 1 to 4 percent yield losses for low infection levels in U.S. ethanol plants could total ethanol yield loss of 147 MMgy to 588 MMgy. In that context, Van’t Hul considers cleaning and sanitizing an area of 100 percent opportunity for ethanol plants. “I think costwise, people really haven’t looked at it enough to truly understand what the opportunity is to switch some costs away from antibiotics to cleaning and at that end of the day, how that would impact yield and performance through the plant,” he says.
Beyond just collecting data, ethanol plants need to analyze it to find and correct problems, says John Friedig, manager of plant optimization services for ICM Inc. Instead, some plants have a tendency to just buy more antibiotics. “But that adds to the cost to produce a gallon of ethanol and at these times and margins that’s not the correct thing to do,” he says. “You’ve got to put a little blood and sweat into finding the root cause of why you are running higher lactic acids or acidic acids. It’s not something that you find in a day.”
ICM emphasizes the importance of reducing infection levels by examining an ethanol plant’s piping, reducing dead legs and other areas where bacteria can grow. Sam Vander Griend, process development manager for ICM, pointed to an old saying, “An ounce of prevention is worth a pound of a cure.” An ethanol plant CIP system is much more effective if it isn’t constantly battling existing bacteria.
Fouling falls into two categories, protein and mineral, Vander Griend says. Mineral fouling varies from plant to plant, depending on water quality, which means it’s important that each plant is using the correct cleaning or raw water treatment method for the type of fouling it is experiencing.
Fouling prevents efficient heat exchange, causing an ethanol plant to consume more energy to complete the same amount of work. With today’s low cost of natural gas and electrical power, that might not be a huge concern. “The cost impact of having a nonoptimally clean system is probably fairly minimal in the scheme of things,” Robert says, “but as soon there’s a shift again in utility costs, that whole dynamic can change very rapidly.” In other words, if natural gas prices go up, he predicts it will separate the well- managed and maintained ethanol plants from those with lax cleaning procedures and extreme fouling problems.
Proper CIP practices, chemistry and equipment can also help reduce maintenance costs and save wear and tear on equipment. Consider an ethanol plant’s evaporator tubes, Fernholz says. A company with a good CIP system won’t have to spend as much on cleaning and maintenance to unplug its evaporator tubes if it has been cleaning properly throughout the year. “It’s just like your oven. If you clean your oven often you don’t have to go in there with Easy Off and a chisel,” he says, adding that it’s less expensive to maintain. Then there’s the cost of repair to consider. “If it goes on too long you can end up with deformed steel and cracked tube plates and major capital repairs required.”
Solving fouling issues can be a fairly complicated proposition, requiring a look at the original equipment design specifications and the expertise of engineers, Robert says. The idea is to check out the technology provider’s specifications for items such as pressure drops and flow velocity profiles to determine if current operation falls within the original design parameters. That’s difficult to do “in the heat of the battle” of daily operations, he says, but if the problem is ignored too long it can create long-term problems. Touching on the same topic, Fernholz points to CIP supply pump flow rates. Is the pump undersized or is it big enough to handle the flow rate needed for proper cleaning? “If there is one thing I see consistently, it’s undersized CIP supply pumps,” he says.
Solids, or beer stones, in the CIP wash water is another issue that impacts some ethanol plants more than others, depending on their water quality situation. Solids can damage equipment, such as CIP spray nozzles, and can build up in the fermentation tanks. Ideally, an ethanol plant should filter solids to between 200 and 300 microns, Humphries says, but not all plants have filtration systems in place. A self-flushing filtration system from Tank Cleaning Technologies costs between $20,000 and $30,000. “That’s not very much money when you consider that dumping that probably costs 70 to 80,000 dollars, a year,” he says, “and that’s not counting the costs of chemistries.”
Humphries has seen ethanol plants with as much as 30 percent solids in their CIP wash water—worse than an offshore drilling rig, known to be the industry with the worst problem with solids. The company worked with a Canadian ethanol plant, Noramera Bioenergy Corp., Weyburn, Saskatchewan, which had a fairly efficient CIP system but no filtration. The company had a severe solids problem that caused frequent clogging of the cleaning head, requiring it to take fermentation tanks out of service every 30 to 45 days. “They were looking for a short-term solution, which became long-term solution for them,” he says. The company equipped Noramera with a cleaning head that could handle high solids, which has made a dramatic difference. “They’ve been out there for five years, without one stoppage,” he says.
Optimizing an ethanol plant’s CIP system can also reduce water use and chemical costs, although this isn’t an area ethanol plants have really delved into as other industries have, Humphries says. He points to Coca Cola’s efforts at reducing water usage at a bottling facility that is about the same size as an ethanol plant. “Just one plant in California, through CIP optimization, saved water usage into the thousands of tons of water a year and put the bottom line over $3 million dollars,” he said. “So it’s pretty big.”
Robert sees a need for industry collaboration on CIP best practices documentation, tailored specifically for ethanol plants. He believes there’s room for improvement in the CIP chemistry and procedures ethanol plants utilize. To illustrate, he points to the changes in the yeast and enzymes first used in ethanol plants. Back in the mid-90s, the ethanol industry utilized products developed for the beverage alcohol industry. Over time, industry-specific yeast and enzymes were developed and an ethanol plant today would never think of going back to the old products. “I believe the same thing would hold true, if we got working much more diligently in the areas of CIP and cleaning the systems,” he says, adding that it would enhance long-term profitability. Partnering with chemical cleaning companies to identify better CIP chemistry is an opportunity to bring ethanol expertise and chemical expertise together. “They can help accelerate the learning curve,” he says.
The ethanol industry hasn’t traditionally considered more performance-based chemistries beyond the current use of sodium hydroxide, Van’t Hul says. However, with the marriage of Ecolab and Nalco, the two companies are well-positioned to assist in this area. In fact, the company is now planning field trials in an ethanol plant to test new chemistry and nonantibiotic methods of yield-loss management, Fernholz says. One potential benefit is reducing the time needed for a CIP cycle, which would allow an ethanol plant to push more product through the plant or increase fermentation time for higher yield, Van’t Hul adds.
The other side of the CIP chemistry coin is system automation. Compared to other industries, the ethanol industry is less automated, Alwin says, with more processes, including CIP, completed manually by plant employees, even though they could potentially be automated. “George knows how to do it,” he says. “George can open that manual valve on the concentrate and watch his wristwatch and count out how many gallons of sodium hydroxide he needs to put in there.” The problem is what he calls the human error factor. What if the employee passes out in the middle or is paged and walks away to take a call—something Alwin has actually watched happen, resulting in $10,000 in wasted chemical.
Friedig agrees that automation can make things faster, safer and more consistent. If CIP procedures are labor-intensive it can get tempting, over time, for operators to cut corners. “Human nature is to take the path of least resistance,” he says. On the other hand, although automation is important, there’s still value in doing a physical or audible check to make sure systems are operating correctly. That means periodically listening for the audible sound of the spray ball operating, physically removing spray balls and checking to make sure CIP pump discharge pressure is maintained. “That should be done on a routine basis, if plants are keeping up on preventative maintenance,” he says.
Author: Holly Jessen
Features Editor, Ethanol Producer Magazine
CIP for Advanced Biofuels
If clean-in-place systems are important at grain-ethanol plants, they are even more vital at advanced biofuel facilities. For maximum efficiency and to avoid system crashes, the equipment has to be “uber super clean,” says John Hyde, chairman and founder of Hyde Engineering and Consulting.
Among other things, the Colorado-based company works with the pharmaceutical, biopharmaceutical and biocommodity industries to design CIP and sterilization-in-place systems, including at specific cellulosic ethanol production facilities. Hyde believes it is critical for CIP to be integrated into the design from day one. Doing so can come with significant capital cost savings and improve the chances of success dramatically.
Unfortunately, however—similar to when the first generation ethanol industry was emerging—the advanced biofuels industry doesn’t completely comprehend the necessity of effective cleaning. “In our experience, especially with biocommodity plants, and within that especially ethanol plants, CIP is often considered as afterthought,” Hyde says.
For example, he’s seen plants with sections of pipe left out of the cleaning circuit design or with vessels or pipes that don’t drain. Drainage is a key feature needed for effective residue removal, and without it the process is vulnerable to contamination.
Cleaning is particularly important for facilities utilizing a genetically engineered organism for fermentation. These organisms aren’t typically as hardy or as fast-growing as nongenetically engineered, native species, he says. If a native species contaminates the process, it will out-compete the genetically engineered organism.
At smaller scale, fermentation equipment can be steam sterilized to get rid of all possible competing microorganisms. “In production-scale equipment, that’s virtually never done,” Hyde says. “It’s just not economically feasible to design vessels that big that can hold the pressure that the steam would require.”
Instead, commercial-scale advanced biofuels facilities typically install a scaled-up version of a CIP system, such as what’s utilized by the pharmaceutical industry. Again, similar to the CIP process in use by the corn-ethanol industry, this likely involves the use of heated water and sodium hydroxide mixture to remove postproduction residue, a potential trap for bacteria and other microbes, he says.
The solution is sent through pipes at high velocity and cleans tanks by spraying and generating turbulence. Some companies also add a sanitizing rinse of other solutions, such as hypochlorite or iodine-based products, for surface decontamination. Provided the facility does a reasonable job of cleaning, any remaining bacteria will be killed by high pH and temperatures, Hyde says.
Taking CIP Blending To the Next Level
Back in 2004, Biofuels Automation started searching for a solution for automated blending of sodium hydroxide for ethanol plant clean-in-place systems. “We saw so many costly manual errors with this procedure,” says Hans Alwin, the company’s business development director, who worked on the project personally.
The result of that search, which the Plymouth, Minn.-based company has marketed to ethanol plants since about 2008, is the Causticity Control Skid, or Causti-Clean. The skid, which comes in two sizes, sits near the CIP blend tank and—using a conductivity-based measurement—gauges the percentage of sodium hydroxide in the CIP mixture. As the mixture is used and becomes spent, a valve automatically opens, adding the correct amount of sodium hydroxide, meaning a perfect dilution every time for more effective sanitation.
Plants that blend CIP solution manually have to send a laboratory technician out to test the sodium hydroxide percentage, a cumbersome process that the Causti-Clean skid completes in less time and more accuracy. Although this may not seem like a problem, plants that have installed the automated system say it’s a big plus. “You don’t realize how much of a hassle it is, until you don’t have to do it anymore,” he says. Instead of taking and testing multiple samples a day, the Causti-Clean requires only a simple calibration every two weeks.
Another valuable feature of the skid is CIP solution filtration, which was originally added to maintain solution cleanliness for an accurate measurement. Although not every ethanol plant has problems with beer stones, Alwin has witnessed some extreme situations. Beer stones are abrasive, potentially causing damage to pumps, pipes and CIP spray balls. He talked to one plant manager who said he spends $25,000 yearly on spray ball maintenance parts and labor due to beer stones. Other plants have to send in their strongest maintenance employee to shovel solids out of the CIP tank. “There’s some plants, depending on water chemistry, that have three front-end loaders full of beer stone solids to remove every six weeks,” he says. For those plants, installing the Causti-Clean can mean significant savings in time and money spent on maintenance.
Still, market penetration of the product has been slow. The company has installed it in about 15 ethanol plants, with the most recent order right before Christmas, he says. Although Alwin still believes the system would still have benefits for most ethanol plants, the automated system may not be as attractive to facilities that don’t struggle with a combination of bacterial infections and beer stones in the CIP solution. The No. 1 factor in whether the Causti-Clean sells well, however, is the price of sodium hydroxide, which fluctuates between 5 and 22 cents a pound. Automation of sodium hydroxide blending eliminates overapplication, a common mistake in manual mode. “We’re pretty confident in universally stating that we reduce the sodium hydroxide chemical use by 25 percent,” he says, adding that's a conservative estimate. With a 100 MMgy ethanol plant bringing in a truckload of sodium hydroxide about twice a week, the savings can be significant. And, although the company doesn’t have any specific data on this, it’s believed that the Causti-Clean aids in better ethanol yield. “Everybody seems to agree that repeatable, effective disinfections help maintain high yields,” he says.