Dennis W. Brinkman
Safety-Kleen Corp.
Elk Grove Village, III.
Recent technology enhancements and a marketing decision to significantly increase volume throughput have combined to produce the next generation of used oil refineries.
The first of these units is in full production in East Chicago, Ind.
With a feedstock capacity of 75 million gal/year, or 4,890 b/d, it is believed to be the largest used oil refinery in the world.
Fig. 1 shows the facility under construction.
While most used lubricating oil is still blended and reprocessed into an industrial fuel, increasing pressures for resource conservation and optimum material utilization have put the focus back on rerefining the "waste" to produce high-quality lube oil basestocks.
Federal procurement guidelines published by the U.S. Environmental Protection Agency (EPA) encourage the use of rerefined oils.' Federal legislation and subsequent regulations directly discussing used oil or indirectly affecting used oil have stressed the importance of properly handling this resource. 2 3 4
Several states have already decided to list used oil as a hazardous waste because of the contaminants often found in the oil as it moves through the recycling system. Contrary to the fears of some, this designation has not caused a decrease in volumes recycled in those states.
Because of the contamination levels and the patchwork (or state-by-state) regulatory environment, it is Safety-Kleen's policy to handle used oil as a hazardous waste, regardless of location.
A key factor in the demise of the rerefining industry over the past 30 years has been the problem of scale.' As environmental, safety, and technological problems have escalated the requirements for waste treatment, storage, and disposal facilities, most recyclers have not had sufficient volume throughput over which to spread the associated costs.
Such requirements typically include water treatment systems, vapor emissions scrubbers, fire protection systems, secondary containment for all storage and processing areas, and a modern laboratory to monitor all materials as they arrive and are stored, processed, and shipped to the customer.
At 75 million gal/year, the plant described in this article is five to ten times larger than those considered economical, and possibly as large as could be practically supported with feedstock as recently as 10 years ago.6
COLLECTION SYSTEM
A key factor in the decision to construct the refinery in the Midwest was the ability to push volumes as high as possible in order to lower the fixed costs/gal ratio as much as possible.
The primary difference permitting the construction of a much larger volume facility is the use of the existing collection system in Safety-Kleen's industrial solvent servicing businesses.
With over 500,000 mineral spirits parts washers and 30,000 immersion cleaners in service at automotive and industrial locations, an extensive infrastructure, including 165 branch distribution/accumulation sites, already existed in the U.S. alone. Adding a service to collect used oil (as well as antifreeze) was a natural extension of current operations.
Further, the purchase of the Breslube Inc. operations and several smaller used oil recyclers brought with it additional facilities and collection networks that allowed the company to rapidly expand to the current combined volume of over 125 million gal/year. This system is now referred to as the SK Breslube division, or SK oil division.
TECHNOLOGY
Once the plant volume and location had been selected, a technology for producing high-quality lubricating oil basestocks was sought.
The consensus of the industry seems to be that the most practical approach is to combine thin-film vacuum distillation and fixed-bed catalytic hydrotreatment, though there have been recent innovations published .7
After investigating several alternative approaches, a decision was made to build on this proven technology.
It is easier to understand the process approach if one first looks at the basic composition of used oils, as illustrated in Fig. 2.
Used oil is composed of dissolved water and solvents kept in solution by detergent/dispersant additives, fuel components and heavier solvents, lubricating oil, dirt, and sludge.
Fig. 2 is a simulated distillation curve, which shows that the contaminants can be separated rather well from the lube oil by distillation.
A flowchart of the plant in East Chicago is shown in Fig. 3. The initial atmospheric flash drum removes the water and light solvents, then the vacuum flash tower removes most of the fuel and heavier solvents.
The aqueous by-product from the first flash is sent for water treatment while low-boiling hydrocarbon contaminants recovered from all steps are combined for use as a fuel within the plant. This fuel has a relatively high chlorine content, which must be taken into account in designing the boiler system.
Vacuum distillation performs the combined functions of separating the lube oil from the heavy ends and generating multiple product streams. Because of the tendency of this material to foul heated surfaces over time, it is common practice to use thin-film evaporators.
The final step is a finishing process involving hydrogenation of the streams over a series of fixed beds of NiMo catalyst. This step is performed in stages to minimize catalyst fouling and to enhance final product quality.
Hydrogenation improves color, odor, and thermal stability while reducing polynuclear aromatics, which are thought by some to be a potential mutagenicity/carcinogenicity source.
PRODUCT YIELDS
As described above, the material entering the plant contains many contaminants. In addition to removing water, solvents, fuel components, and the heavy ends, most modern processes remove as much of the additive packages as possible so that the final basestock is of known quality.
This makes it more attractive to custom blenders and virgin producers who blend the recycled material with virgin material before incorporating the additives. They do not want the basestock to contain additive remnants that might cause problems with their packages.
Some typical data for various process streams are shown in Table 1. As can be seen, each stage of processing removes a somewhat different portion of the contaminants.
The initial flash reduces the quantity of both light ends and water. This reduces the flash point, but does nothing to the metals. The metals are removed in the vacuum distillation step.
Hydrotreating removes higher-boiling halogenates and polar compounds, thereby reducing the acid number.
The Safety-Kleen facility in Breslau, Ont., takes in about 35 million gal/year of used oil and produces about 19 million gal/year of basestocks.
This lube oil yield of about 55% on a raw feedstock basis is typical of a modern operation. It represents a high recovery of the lube oil portion of the waste material (typically around 95% of theoretical lube oil material) .6
Because the new plant is assumed to achieve at least as good an efficiency as the Breslau plant, a yield of around 42 million gal/year (or about 2% of the total U.S. lubricants market) is projected.
Another product is the vacuum distillation bottoms. This material is sold as an asphalt extender or as fuel for industrial furnaces fitted with emission controls. Current expectations are that about 9 million gal/year of vacuum distillation bottoms will be produced.
Thus, this process generates essentially no unusable by-products. Even the spent catalyst from the hydrotreater beds can be sent off for reclamation.
PRODUCT QUALITY
While rerefined oil has been used in automotive and industrial applications for many decades, there has often been a presumption that the quality was not as good as virgin material from crude oil. Marketing of rerefined oil usually involved sufficient discounts to offset this perception.
However, there is no technical reason why rerefined oils should be any different than virgin Oils. The key for either is quality control, as it is in any production process.
The new plant involves significant statistical process control features. The primary tool is a central computer control panel that collects and analyzes data from throughout the plant, generates control charts for visual monitoring, and ultimately assists in improving the overall process, as well as performing the immediate function of controlling the process steps.
The relative quality expected for the new rerefinery can be extrapolated from the quality of the product from the Breslau plant because the process technologies are very similar.
Safety-Kleen has recently completed qualification of a 10W-30 blend using only rerefined baseoils under MIL-L46152 procedures, as documented in Table 2. (MIL-L46152 refers to U.S. Department of Defense military lubricant specifications.) All engine tests were passed on the first attempt.
The engine sequence testing was augmented by a special requirement for the demonstration of basestock consistency applied only to recycled oils. This testing covered over a year of production and showed no more variability than was observed in similar cuts from two major virgin refineries.
In addition, Safety-Kleen is running its own fleet testing, focusing primarily on heavyduty diesel vehicles. Engines dismantled to date have shown no abnormal deposits or wear.
No engine failures have occurred.
ECONOMICS
All of this advanced processing equipment and extensive laboratory work does not come cheaply. A new grassroots facility such as the one at East Chicago requires a capital investment of over $60 million.
The sophistication of the staff members operating a high-pressure hydrotreater or an inductively coupled plasma spectrophotometer is several levels above that of the personnel at the old batch plants.
The obvious question is whether all of this can be put together in an efficient package that produces a profit. This is where a widespread collection/distribution network becomes an important part of the equation.
Safety-Kleen's system of 165 branches, all of which have Resource Conservation and Recovery Act (RCRA) Part B permits and tankage for storage of waste solvents and oils, provides the comprehensive coverage required by this diffuse resource.
The used oil collection system has grown from 36 million gal/year to over 125 million gal/year in 3 years. At the same time, the price received for collecting the oil has increased as generators have become more aware of the enormous cost of using cheaper, but sometimes less stable or ethical, collectors.
The other key feature in the economics discussion is volume. Although a used oil refinery of 10 million gal/year input was considered very large 10 years ago, it is now believed to be much too small.
Regulatory requirements dictate large expenditures for features such as those described. Thus, the size of the plant must be as large as the collection network will allow.
The short-term economics of rerefining will always be controlled, to some extent, by others. This is because industrial fuel prices tend to control the value of used oil, and virgin lube oil prices tend to control the value of the rerefined product.
The rerefining company can give itself a fighting chance by spreading costs over a large volume.
MARKETING
Marketing large volumes of high-quality lube oil from any new facility can be a problem for an independent producer. Marketing large volumes of rerefined lube oil in the 1990s presents added challenges.
Although modern rerefineries can produce high-quality lubricants, a certain stigma, resulting from past problems, exists in some markets involving lube suppliers, equipment vendors, and procurement people.
On the other hand, users are becoming more educated about the quality of rerefined oil and are consciously trying to take advantage of the availability of recycled products in general.
Today SK Oil supplies a wide variety of independent blenders and compounders, as well as major oil companies, with lube oil basestocks.
In addition, a line of blended and packaged oils such as motor oils, hydraulic oils, transmission oils, gear oils, and other automotive and industrial lubricants, are off e red.
Natural market forces, environmental pressures, and likely legislative inducements to preserve this valuable resource instead of destroying it through burning or other one-time uses, are combining to make the future bright for recycling.'
REFERENCES
- "Guidelines for Federal Procurement of Lubrication Oils Containing Re-refined Oil," Federal Register (40CFR252), June 30, 1988, Vol. 53, No. 126, p. 24699.
- Resource Conservation and Recovery Act, P.L. 94-580, 1976.
- Used Oil Recycling Act, P.L. 96-463. 1980.
- Hazardous and Solid Waste Amendments, P.L. 98-616, 1984.
- Mueller Associates Inc., "Waste Oil: Technology, Economics, and Environmental, Health & Safety Considerations," U.S. EPA, January 1987.
- Brinkman, D.W., Whisman, M.L., Weinstein, N.J., and Emmerson, H.R., "Environmental, Resource Conservation, and Economic Aspects of Used Oil Recycling." DOE/BETC/RI-80/11, April 1981, p. 49, 31.
- Kalnes, T.N., Youtsey, K.J., James, R.B., and Hedden, D.R., "Recycling Waste Lube Oils for Profit (UOP Direct Contact Hydrogenation Process)," Hazardous Waste & Hazardous Materials, Vol. 6, 1989, p. 51.
Copyright 1991 Oil & Gas Journal. All Rights Reserved.
