Avoiding Maintenance Migraines

Cleaning, like other preventative maintenance practices, helps avoid the headache of an unscheduled shutdown.
By Katie Fletcher | October 15, 2014

It’s no simple process to schedule ethanol plant shutdowns for cleaning. Although producers agree it takes considerable planning and preparation, it can save time, money and unscheduled downtime in the long run. “If a facility does not make scheduled downtimes for these tasks, the plant will take it for them,” says Matt Werzyn, maintenance manager with Louis Dreyfus Commodities, Elkhorn Valley Ethanol LLC.

Jeff Larson, plant manager at Siouxland Energy Cooperative, agrees. “Bringing it down and starting it up is a timely process, but in the end it is worth it,” he says.

Werzyn points out that, as equipment gets dirtier, it impacts how the plant runs. “As we get closer to shut down, there is a definite performance decrease and an increase in the required energies needed to run the process,” he says.

Not cleaning an ethanol plant could have much more severe consequences than losing a set of keys in a dirty house. “If duct lines are not cleaned over a long period of time, duct fires can result, which can be very expensive, if not destructive, if they occur,” Werzyn says. “Regular cleaning is like any other preventative maintenance. If you maintain the equipment, it will perform its designed task longer and more efficiently, which is cheaper in the long run.”

Squeaky Clean Scheduling
Fall and spring seem to be the prime seasons when producers opt for plant cleaning, but it can occur anytime. “We pick an arbitrary month for shutdown,” Larson says. “We know that we have to shut down in August to do the annual boiler inspection, and then we space the other shutdown from that one.”

Tyler Edmundson, plant manager at Mid-Missouri Energy, a 40 MMgy ethanol plant, says shutdowns are typically based on the condition of the plant’s equipment, the availability of contractors and margins.

Edmundson has found that his plant has been able to avoid a second shutdown the past two years. “Over the years, we have been able track the life of certain disposable parts and found that we could run them longer without having to do anything other than routine preventative maintenance.” He adds that a shutdown in the spring must occur for mandatory pressure vessel inspections by the state.
Whether mandatory or just necessary, scheduling can get tricky during peak shutdown seasons with around 200 ethanol plants in the U.S. “A lot of the ethanol plants use the same contractors and their service calendars fill up fast,” Werzyn says.

Planning ahead is necessary. “Since contractors have to be scheduled so far in advance, sometimes the scope of work changes leading into the outage,” Edmundson says.

Shutdowns are scheduled anywhere from six to 10 months ahead of time for an average of two to five days. If scheduled far enough in advance, Larson says, many, if not all, contractors will work with them on the dates that are chosen for shutdown. “There are certain areas we cannot control, weather, for one, which may force a nonscheduled shutdown,” he says.

Picking a Provider
A number of industrial cleaning service providers offer to take on the dirty work. Decisions on which service provider and cleaning methods to use are thoughtfully made.  “We are loyal to those who have done a good job in the past,” Edmundson says. “If their dates start to fill up and we have not determined when exactly we will be down, they check in with us, which is helpful.”

Mid-Missouri Energy uses the services of Hydro-Klean LLC, but not all producers always stick with the same contractor. Larson, who currently works with Seneca Companies, has used four different vendors at Siouxland Energy. When shopping around for a service provider, he asks other producers for recommendations. “There is a lot of networking that happens in this industry, and I think that does help,” he says.

Werzyn at Elkhorn Valley Ethanol also chose a provider based on references from other plants. North American Industrial Services, formally Freez-it-Cleen, has serviced that plant.  Other traits producers look for in service providers, besides availability, are safety and training records as well as experience in the ethanol industry, Edmundson adds. 

Shutdown Prep and Precautions
Specific tasks to accomplish during the shutdowns are also scheduled. “Any task not completed is carried forward to the next shutdown,” Werzyn says. “The work list is compiled over those six months, plus there are scheduled tasks that are on an automatic schedule.”

Several people are usually involved in the planning process. “Myself, the maintenance manager and the environmental health and safety coordinator typically work together on scheduling and making sure we have the proper documentation, training records, etc.,” Edmundson says. “Safety is the No. 1 priority—making sure contractors have proper credentials and understand our policies and expectations.”

ElkHorn Valley Ethanol sends a contractor safety packet, which Werzyn says, “contains a letter outlining our general safety rules,” he says. “And we request a copy of their OSHA 300 log and a copy of their employee training records. Once their work crews are onsite, they must attend a contractor orientation before they are released to work.” After each shutdown the Elkhorn staff holds a post-shutdown review meeting to reflect on what went well and what could be improved.

Larson and his team at Siouxland contact utility providers and marketers six weeks before a shutdown and let them know one is scheduled so everyone is informed and can prepare.

Cleaning Method
Over the years, the need for annual to semiannual cleaning hasn’t diminished, but how it’s done has changed. “Initially the cleaning of a system like duct work would take a longer time because it was never done before,” Werzyn says. “Now that many tasks are preventative-maintenance generated, it is done every year or every six months, and the cleaning time required is fairly constant.”

Many plants use in-house, clean-in-place (CIP) systems to help prevent fouling and bacteria contamination, which, in turn, lightens the enormity of the contractor’s clean-up job during shutdown. Edmundson mentions new chemicals, enzymes and in-house caustic and acid CIP procedures as being helpful. “With current margins and how hard the plant is being run, fouling issues would be hard to stay on top of if in-house methods were not part of daily operations,” he says.

When it comes to cleaning methods deployed at the plants, producers use either hydroblasting, dry-ice blasting or a combination of both, as well as chemical circulation processes, vacuum services and others, based on a plant’s needs. “At this facility, we use high pressure water blasting to ‘punch’ tubes in the eight evaporators,” Werzyn says. “Dry ice blasting is used on the fin tube heat exchangers in the heat recovery steam generator and in the three-stack economizer units. Dryer interconnecting duct work gets cleaned with dry ice sponge media.”

Similar to Elkhorn Valley, a combination of dry ice and hydroblasting are used at some plants, Werzyn says. Mid-Missouri Energy uses hydroblasting on the plant’s evaporators, distillation vessels, product lines, tanks, dryers and dryer ducting, Edmundson says. Dry ice blasting is used on the plant’s centrifuges, economizers and air-to-air preheater, typically. “Refractory is the main reason we prefer dry ice,” he says. If the ceramic fiber modules used for insulation gets wet, it may need to be replaced.

Werzyn says another advantage of the dry ice method is that it is gentler on the steel fins used to increase surface area. He adds that dry ice reduces water usage and eases clean up. “All the water that would be used in a water blast method must be kept within the plant and processed through. This takes a lot of energy to complete and can reduce the time to return to full rates,” he says.

Some producers opt for hydroblasting over dry ice. “We don’t have the issue with getting rid of the water like other facilities might,” Larson says about Siouxland Energy. “We can hold quite a bit of water here at the plant.”

Some service providers have started offering a chemical circulation process for cleaning the shell side of the exchangers to remove scale buildup on the steam side of process vessels. Seneca and Mist Chemical performed this process at Siouxland Energy. Larson says it gave him and his team “peace of mind.” The process has also been used at ElkHorn Valley Ethanol. “The CIP of the shell side of the exchangers has made the vessels more efficient in their ability to evaporate,” Werzyn says.
Author: Katie Fletcher
Staff Writer, Ethanol Producer Magazine
[email protected]