After several years of settling for an oil removal method that was inefficient and ineffective, a soybean processing operation turned to a vacuum truck service for help. Although this service was able to remove oily water from the company's below-ground pit, it had to be done several times a month and that was far too costly to sustain in the long run. So, the plant maintenance and engineering department went in search of an oil removal process that was efficient, cost effective and sustainable.
The plant, located in the Midwest, operates a high-volume facility that makes soybean oil. Soybean oil is a very popular and widely used oil that is extracted from the seeds of the soybean. It is a complicated process, but in short, the soy kernel is cracked by putting it under hydraulic pressure with a hexane solvent. In addition to soybean oil, by-products of the process include soybean meal which can be used for used for animal feed and for industrial biodiesel fuel.
Some waste oil is generated from residual soybean oil derived from the extraction process that combines with trace amounts of hydraulic oil that emanates from the hydraulic-driven presses and machinery.
When the processing equipment and facilities are cleaned, these waste oils are washed away and combine with the plant's maintenance wash water. The resulting oily water drains to a below-ground collection pit in an outdoor wastewater management area. The pit is surrounded by safety guard rail. The area is rated as an explosion proof zone because of the presence of flammable hexane solvent used in the extraction process.
When the wastewater management area was originally constructed, drum type oil skimmers were installed in the pit as a means of continuously recovering oil floating on the surface of the wastewater. This type of skimmer presented several challenges in this application.
First, because the unit itself actual floats in the oily wastewater, over time the unit became impregnated with oil building up on it and in it, eventually interrupting the flow of oil and precluding it from being pumped away to a collection vessel.
Second, its rotating oleophilic element floating in the oil follows a fixed path, so floating debris tended to accumulate in front of the device and block oil from reaching the skimmer.
Third, even when there was no floating debris in the way, the unit has no "reach" and if the oil didn't find its way towards the skimmer, it wouldn't be collected.
The monitoring and manual intervention required to keep this type of oil skimmer working became a burden to the maintenance staff at the processing plant. During the cold winter months, low temperatures would cause the oil to solidify, amplifying the issues and inefficiencies of the equipment in place. So, the decision was made to retire the drum oil skimmers and replace them with a vacuum truck service to address the plant’s oil removal needs.
When the plant started using a "vac truck" service they realized a new set of issues. The facility's oil removal needs were continuous, but service visits by the vacuum truck were occasional. Once the truck pulled away, the oil began to accumulate in the pit once again. Keeping up with the oil removal required more frequent visits from the vacuum truck, which led to added, recurring costs. In addition, while the service did a good job of removing the oil, it sucked up a lot of water in the pit along with the oil. Because the vacuum service charges by total volume removed, as well as for each visit, the combination of frequency of visits and the volume removed, much of it being water, made the vac truck an extremely expensive process.
As the facility manager at the extraction plant explained, “The vac trucks were effective, but certainly not efficient, and very expensive. We ended up paying for them to remove not just the oil, but also a lot of water that got taken away with it.”
The facility's management team knew they needed a more efficient, affordable and sustainable approach to their oil removal challenges. Online searches led them to the Oil Skimmers, Inc. web site where they reviewed the Oil Skimmers, Inc. line of oil skimmers, skimming systems and oil water separators, and learned about their considerable experience and applications knowledge gleaned from over 50 years in the oil removal solutions business.
After submitting an initial inquiry, and receiving a prompt, thorough response from the Oil Skimmers, Inc. regional and local representatives, the maintenance team at the soybean plant realized Oil Skimmers, Inc. had decades of expertise in providing solutions to the waste oil removal challenges presented in soybean plants around the world, and could provide them with an efficient, reliable, and affordable approach that would perform well year-round.
Oil Skimmers, Inc. assessed the plant’s application by understanding each of their challenges and reviewing their wastewater pits and the entire wastewater management area.
“The customer had a good understanding of the problem, and we reviewed all of the plant’s requirements,” said David Cehlar, Regional Manager at Oil Skimmers, Inc.
“We put a team together, listened carefully and got to work. Oil Skimmers, Inc. has provided oil removal solutions in many applications just like this around the globe. We have a significant inventory of potential solutions to bring to bear. But every situation is unique. We can employ standard solutions, we can customize those solutions, or we can develop a completely new solution to meet our customers’ specific needs.”
Oil Skimmers, Inc. prepared engineering renderings of the site, designed several possible solutions sets, and reviewed them with the soybean plant's management team.
In the end, Oil Skimmers, Inc. provided a multi-stage oil removal system that consisted of a Model 6V Brill® tube type oil skimmer with an insulated Oil Skimmers, Inc. Hi-Flow Sludge Funnel Spout, both mounted to a customized Oil Skimmers, Inc. Guard Rail Mounting System that was attached to the customer’s safety guard rail surrounding the wastewater pit. The “guard rail mount” was customized so that the oil skimmer could reach past the wall of the pit to avoid interference, and high over the pit to leverage gravity to move the oil once it is picked up. The collected oil was kept in a custom designed heated reservoir before being pumped into a nearby collection tank.
Unlike the drum type oil skimmers used in the same application years before, the Brill tube type oil skimmers are uniquely suited to this application. They are designed to ensure consistent operation, with minimal maintenance required. The Brill tube type oil skimmers utilize a closed-loop Free-Floating Collector Tube™ to pick up the oil. In the Brill system, only the collector tube touches the thick, oily water. The rest of the system stays out of the water. The tube floats freely on the water’s surface and the oil adheres to the outside of the tube, which is continuously driven across the surface of the water, and then pulled up into the system and through a set of scrapers that remove the oil, before sending the tube back into the pit to fetch more oil. The tube is designed to attract only floating oil, so the water remains in the pit. The collector tube is unaffected by floating debris and automatically adjusts to fluctuating water levels. It doesn’t follow a fixed path, so it’s able to snake over, under and through debris to continuously pick up oil.
Once the oil is picked up by the Model 6V oil skimmer, the next challenge to overcome in this application is moving the oil to a designated collection tank. The waste oil from soybean processing requires operating temperatures of 170 degrees to keep flowing. In lower temperatures it quickly solidifies. So, to keep this viscous oil flowing once it is recovered by the skimmer, the application demanded the Oil Skimmers, Inc. Hi-Flow Oil Discharge System. The Hi-Flow was designed to accommodate the thickest and most difficult fats, oils and grease that would choke other collection systems. The thick oil recovered by the Model 6V drops directly into the Hi-Flow’s collection spout that is designed to promote oil flow and prevent buildup. The spout is able to be heated and insulated to maintain the 170˚ temperature required to keep the oil flowing.
From there, the Hi-Flow spout directed the soybean waste oils into a custom-designed oil collection reservoir. The reservoir sits directly below the Hi-Flow’s spout to allow enough oil to accumulate before a 2” air-operated double diaphragm pump transfers it to a nearby 300-gallon tank. The pump is controlled by an adjustable pneumatic timer in the system’s explosion proof control panel which regulates the transfer of oil from the collection reservoir to a larger tank. When the pump activates, the oil is moved from the reservoir to an Oil Skimmers, Inc. 300-gallon collection tank, that is heated, insulated and explosion proof.
The entire system was wired to an explosion proof control panel which included controls for the oil skimmer, thermostat, heat, and transfer pump.
The soybean processing plant reports that they are satisfied with their new oil removal solution and all components of the system are performing as designed.
“The waste oil is being skimmed and is flowing easily to our collection tank – even when the temperature drops below freezing. No more oil build-up like our old skimmers,” shared the Facility Manager.
The comprehensive oil removal system designed by Oil Skimmers, Inc. addressed each and every one of the issues the plant experienced with their previous solutions. The Brill tube-type oil skimmer doesn’t clog, doesn’t get blocked by debris, doesn’t require frequent maintenance or adjustment, and doesn’t pick up a lot of water. The Hi-Flow funnel spout keeps the thick oil flowing. The Guard Rail Mounting System places the system in ideal position for operation, access, and maintenance. The collection reservoir and transfer pump regulate the flow of recovered oil to the 300-gallon tank.
The Facility Manager added, “This system really checks all the boxes. We are saving lots of money because we don’t need the vac trucks anymore. We are saving lots of time and labor because our maintenance team can trust the new system to just plain work. We’re confident now that we have the right oil removal solution in place. It’s effective, efficient, rugged and reliable - all year ‘round.”