Cleaning Comes with Choices

Quality service providers offer wide variety of techniques, mediums to meet plant needs. Spongeblasting and other techniques discussed in this contribution from the June print edition of Ethanol Producer Magazine.
By Mark Parenteau | May 18, 2017

When it comes to industrial plant cleaning, there is no one right way to effectively get the job done. In fact, ethanol plant managers have many choices to make when deciding how to get their plant as clean as possible for optimal performance. They can choose one service provider for the entire cleaning contract, or they can hire multiple companies to perform different aspects of the cleaning. They can also choose which combination of cleaning techniques will best suit their plant’s design.

Typically, a mix of wet and dry techniques is necessary for proper cleaning to protect the different equipment used throughout the plant and to achieve optimal performance. Every method and medium has its own pros and cons, however, so staying up-to-date on available techniques and best practices can be very beneficial for plant managers. Which set of techniques is the right fit for your particular plant? Let’s review the options available.

Dry Methods
Dry ice, sand and sponge are the three most common types of dry cleaning materials.
Sand blasting is a cleaning technique that has been around for centuries. While it is an affordable and effective way to clean, it is also very aggressive and presents some risk of damage to both the equipment and the worker. Sand blasting can profile equipment, making it more susceptible to dust and grime and ultimately requiring more frequent cleanings. Also, workers who use sand to clean are exposed to increased risk of dust inhalation, which can lead to health issues.

Slurry blasting—a combination of water and sand—is sometimes used as a solution to this issue. Some states have even passed regulations requiring slurry blasting to be used instead of sand blasting for outdoor applications because slurry produces a more containable waste stream as compared to sand. Some OEMs require sand to be used to clean their products. It is important for plant managers to know which items may have such restrictions.

Other dry cleaning methods include dry ice and sponge blasting. The two techniques are comparable methods in cost and cleaning ability, but the mediums are very different.

Sponge differs from other dry media in that it can be used near rotating equipment and adjacent coatings without being concerned that the material will ricochet. Premium Plant Services began offering sponge blasting in 2012 as an alternative to dry ice cleaning for duct work, energy centers, dryers and other applications, in response to plant demand.

Sponge blasting is a precise method for cleaning; however, it is less powerful than some other methods. Therefore, more time is required for proper cleaning. While it does take more time, emissions and dust are not an issue when using sponge to clean, so it is a safer option than sand for cleaning crews. Sponge is also more environmentally friendly than other cleaning mediums. Sponge can be recycled multiple times on site at each job, which reduces waste. More importantly, sponge requires no water, eliminating run-off concerns and the need for auxiliary tanks to hold used water. Finally, unlike wet cleaning methods, sponge blasting leaves no slippery floors behind, doesn’t present electrical hazards and eliminates the risk of expensive pieces of equipment rusting out after the job.
While it does have many positives, sponge blasting is not the perfect technique for all applications, and there are certain specific precautionary measures that should be taken. For example, plants that produce distillers grains must be extra cautious when using sponge for cleaning, particularly if the sponge medium used by the contractor contains aluminum oxide. Plant managers who choose to use sponge to clean those plants should plan for extra time to sweep and vacuum all nooks and crannies of the area carefully to ensure no media is left behind.

Wet Methods
Hydro blasting with water has been a top choice for industrial plant cleaning for decades, and continues to be the most popular form of cleaning for ethanol plants. The reasons are simple: It’s cost effective, fast and efficient.

Hydro blasting requires the least amount of manpower of any cleaning technique, which is what makes it cost-effective and efficient. Hydro blasting equipment can utilize 350 HP (horsepower). Sponge blasting equipment, by comparison, maxes out at 132 HP. A wider variety of tools is available to aid in hydro blasting as well, which can speed the process. Confined spaces can be cleaned by a mechanical device, for example, which limits safety concerns for cleaning crews. By contrast, when using dry methods like sponge blasting, personnel must climb into the confined space to clean the area. It’s fairly dangerous, and some plants require a rescue team to be onsite as a precautionary measure, which increases the time and cost for the project.

Water is most likely to be used to clean areas of the plant where sponge and other dry media are not useful, such as distillation units and exchangers. Additional benefits of hydro blasting include no dust, no risk of profiling surfaces, and no need to postpone service times in case of inclement weather. A little rain makes no difference when your cleaning medium is already water.

Hydro blasting is not always the ultimate cleaning solution, however. Thousands of gallons of water are required for each cleaning, which requires precautionary measures to prevent run-off, auxiliary tanks for holding water and other preparatory steps. Through experience, though, some service providers have greatly reduced the amount of water. Premium Plant Services has reduced the typical amount of water it uses when cleaning an energy center in a 50 MMgy ethanol plant from 30,000 gallons several years ago to less than 15,000 gallons currently, and continues to further reduce the amount of water needed for cleaning.

Choosing the Right Mix  
The ideal cleaning solution for most ethanol plants is a combination of wet and dry applications. A dry medium like sponge can perhaps best be used in sensitive areas of the plant such as the energy center. And while sponge can also be used to clean structural steel, tanks and other areas, most plant managers find that its environmental benefits do not outweigh the increased cost and time for the majority of the plant’s cleaning needs. In those areas, hydro blasting continues to be the most likely choice for efficient, quality cleaning. A perfect combination, for example, could include using dry ice on the RTO economizer, sponge on the fans, and water for other areas of the plant.

Plant managers should ask questions when consulting with a cleaning contractor to find the mix of approaches that works best for their plant. A quality cleaning company will provide advice and help identify the best solutions. If they don’t, seek out a company that will.

Author: Mark Parenteau
CEO, Premium Plant Services