New lubes plants use state-of-the-art hydrodewaxing technology

Hydrodewaxing processes produce clean, high-quality base stocks suitable for use in new finished lubricant grades. Shown here is a sample of the water-white base oil that Excel Paralubes produces at its new Westlake, La., plant (Fig. 1).

Excel Paralubes, a 50/50 joint venture of Conoco Inc. and Pennzoil Products Co., was the first to license Chevron Research & Technology Co.'s Isodewaxing process. Shown here is Excel Paralubes' new 18,000 b/d lubes complex in Westlake, La. (Fig. 6 [10,696 bytes]).

Two new lubricant base oil plants are using state-of-the-art hydrodewaxing technology to produce clean, high-quality base stocks (Fig. 1 shown above).

The hydroprocessed base stocks are particularly suited to producing new grades of finished lubricants.

Excel Paralubes, a 50/50 joint venture of Conoco Inc. and Pennzoil Products Co., started up an 18,000 b/d plant in Westlake, La. (OGJ, Apr. 21, 1997, p. 27). And Petro-Canada has expanded base oil production at its Mississauga, Ont., plant by 7,500 b/d.

These two projects have increased North American base oil capacity by almost 10%. In addition, China National Petrochemical Corp. and China National Petroleum Corp. have added 16,000 b/d, or almost 33%, to China's base oil capacity in the past 2 years (OGJ, July 7, 1997, p. 44).

As a result of these capacity additions, world production capacity for lube base stocks has increased almost 117,000 b/d, or 15.5%, in the past 2 years (Table 1 [13,158 bytes]). This increase has led to surplus supplies, and even some shutting in of capacity.

Base stocks, lube oils

Finished lubricants contain 70-99% base oils. The American Petroleum Institute's base oil specifications are shown in (Table 2 [10,621 bytes])

Conventional base oils fall into API Group I and are produced by separation processes such as distillation, solvent extraction, and solvent dewaxing. (Fig. 2 [26,211 bytes]) shows a conventional processing scheme for producing base oils, waxes, and white oils.

Newer processing schemes involving severe hydrotreating and hydro-cracking, however, are being used to make Group II base oils. These hydroprocessed oils contain much lower levels of aromatics, sulfur, and nitrogen, compared to Group I stocks (Table 3 [8,456 bytes]). The performance properties of API Groups I-IV base stocks are shown in (Table 4 [29,048 bytes]).The International Lubricant Standardization & Approval Committee (ILSAC) determines finished lubricating oils grades. The Group II base stocks produced by hydroprocessing schemes are used in ILSAC GF-2 finished lubricants. (ILSAC is expected to issue GF-3 specifications in 2000.)

Catalytic dewaxing

Gary Everett, director of licensing for Lyondell Petrochemical Co., and Art Suchanek, manager of technology development for Criterion Catalyst Co. LP, compared the available catalytic dewaxing technologies in a paper presented at the 1996 National Petroleum Refiners Association annual meeting.

"The initial move away from solvent refining to remove wax compounds began with catalytic dewaxing (CDW), which relied on shape-selective mole sieves to effect the selective 'cracking' of long-chained normal paraffins," say Everett and Suchanek. "Later, noble metals were added to the catalyst structure to create a bi-functional catalyst that would achieve some wax isomerization as well as shape-selective cracking."¹

This second process they term "Iso-CDW." It is exemplified by two processes available for license:

Isodewaxing, developed by Chevron Research & Technology Co., Richmond, Calif. (Fig. 3 [19,437 bytes]).
Mobil Selective Dewaxing (MSDW), developed by Mobil Oil Co., Fairfax, Va. Everett and Suchanek say a third CDW route is to isomerize the wax fraction separated via solvent dewaxing. This approach uses a catalyst designed primarily for n-paraffin isomerization, and is mostly used for producing base oils with a very high viscosity index. (Table 5 [51,266 bytes]) shows a comparison of the process conditions and product characteristics of the CDW, Iso-CDW, and wax isomerization processes.

Yukong Ltd., Seoul, is producing base oils using a processing scheme called Unconverted Oil (UCO). (UCO employs Isodewaxing). A flow diagram of the Yukong process is shown in (Fig. 4 [29,631 bytes]).Yukong reports that base stocks produced via the process have a viscosity index of 123.2 Lube oil yields are about 59%. Unit investment costs were $70 million in 1994, and operating costs were $19.20/bbl, including depreciation, return on investment, maintenance, and overhead costs. (This compares to operating costs of $35/bbl for conventional schemes.) ²

The new plants

The new Excel Paralubes and Petro-Canada plants combine hydrocracking and Isodewaxing to produce the new-generation base stocks. Isodewaxing provides the ability to produce base stock from a broader range of crudes containing higher levels of sulfur.

The process differs from conventional base oil dewaxing in that it isomerizes the wax molecules rather than removing them. This not only increases yields, but also boosts viscosity index, reduces volatility, and improves oxidation stability (Fig. 5 [18,458 bytes]).These improvements in product performance and quality make the new base stocks especially suited for new grades of motor oil (GF-3, and later, GF-4, for passenger cars; and PC-7 for heavy-duty vehicles).

The Isodewaxing process was demonstrated commercially at Chevron's 14,000 b/d Richmond lubes plant in 1993. Chevron's first commercial license was to Excel Paralubes in 1994. The Petro-Canada project was the second Isodewaxing license.

"We are very pleased with the continued commercial success of our technology," said Al Caccamo, former president of Chevron International Oil Co.

Excel Paralubes

The Excel Paralubes plant started up earlier this year on a site adjacent to Conoco's 226,000 b/d Westlake refinery (Fig. 6 [10,696 bytes]). The plant uses state-of-the-art technologies to produce water-white lubricants.

The main units are a 32,000 b/d UOP hydrocracker and a 20,000 b/d Isodewaxing unit. Vacuum gas oil (VGO) from Conoco's refinery is fed to a vacuum distillation tower, where 15,000 b/d of lighter distillates are removed and returned to the refinery.

The hydrocracker, operating at 3,000 psi and 1,000° F., converts the waxy gas oil and removes sulfur and nitrogen impurities. The effluent flows to the dewaxer, which improves the pumpability of the base oil and enables it to resist the formation of gels, even at low temperatures.

The dewaxed stream is hydrogenated to remove aromatics and stabilize the product. In the dewaxing section, a saturated-gas plant removes propane, butane, and naphtha from the reaction products.

The lubes plant has two sulfur-recovery units, each with a capacity of 90 long tons/day without oxygen enrichment, and 180 long tons/day with oxygen enrichment. Oxygen and nitrogen are purchased from a nearby pipeline.

A 2.5 million bbl tank farm stores feedstocks and products for the lubes plant.

In order to produce feedstock for the lubes plant, Conoco has implemented a $250 million expansion at its Westlake refinery to increase VGO output. The expansion included:

40,000 b/d atmospheric distillation capacity
60,000 b/d vacuum distillation capacity
34,000 b/d catalytic reforming capacity.

Hydrogen from the new UOP Platformer is used in the lube oil hydrocracker.

Petro-Canada

According to David McFall, contributing editor for Lubes 'n' Greases magazine, "Petro-Canada was the first base oil plant in North America to abandon solvent refining in favor of hydro cracking, with solvent dewaxing." ³ With the addition of the new plant, Petro-Canada doubled base oil capacity at its Mississauga, Ont., site to 15,000 b/d.

The new 7,500 b/d lubes plant combines hydrocracking with Chevron's Isodewaxing and Lube Hydrofinishing processes. The $100 million (Canadian $135 million) project uses these technologies to convert lube feedstocks into high-quality base oils.

Lubes markets

These projects and other capacity expansions have produced a world base oil capacity of almost 948,000 b/d. Industry observers say the Excel Paralubes and Petro-Canada plants have added 25,500 b/d to North American base oil capacity, which was already oversupplied by 5-8%. ⁵

The oversupply may depress lube oil prices. In addition to the overall market imbalance, demand increases for the new base stocks are expected to outpace capacity additions, creating a shortage after 2000, which may cause producers to convert some existing solvent-based capacity to hydroprocessing capacity.

(Fig. 7 [17,186 bytes]) shows a possible supply scenario, composed by Lubrizol Corp.'s Margaret Lemmon, Kirk Metzger, and John Taracha.⁴

To adjust to the changing market, Conoco plans to phase out its solvent-refined products by early next year, reported Deborah Hairston in Chemical Engineering magazine.⁵ And Petro-Canada's plans call for converting most of its finished lubricants to the new base stock, according to Hairston.

In a similar move, Star Enterprise plans to convert its Port Arthur, Tex., base oil plant to hydroprocessing, and has licensed the Isodewaxing process. Its existing 16,500 b/d lubes plant will be shut down when the new 15,000 b/d plant comes on stream in the latter part of 1998. The new plant will be designed to produce base oils to API Group II and Group III standards.

Also, as an adjustment to changing markets, Lyondell-Citgo Refining Co. Ltd. (LCR) shut down 1,700 b/d of solvent-neutral base oil capacity because of increased competition and falling margins in the solvent-neutral base oil market. According to a written announcement from LCR's Dave McNiel, vice-president of manufacturing, and Joe Thiel, manager of lubricants, "These new plants are going to produce a higher-quality product and take their share of the existing market."

LCR retains 5,300 b/d of naphthenic base oil capacity. "We will remain in and we expect to grow our naphthenic oil, white oil, and compounded oil businesses," said Thiel.

LCR recently completed a $1.1 billion heavy-oil upgrade project at its Houston refinery (OGJ, Mar. 21, 1994, p. 60). As a result of the expansion, the refinery has excess hydrogen supply. LCR is conducting a lubricants technology evaluation study to determine the future viability of various options for manufacturing severely hydroprocessed base stocks.

References

Everett, Gary L., and Suchanek, Art, "Lubricant Oil Production: The Proper Marriage of Process and Catalyst Technologies," NPRA annual meeting, Mar. 17-19, 1996, San Antonio.
André, Jean-Philippe, Hahn, Soo-Kuhk, Kwon, Sook-Hyung, and Min, Whasik, "An Economical Route to High Quality Lubricants," NPRA annual meeting, Mar. 17-19, 1996, San Antonio.
McFall, David, "Petro-Canada Builds a Base Oil 'Boutique,'" Lubes 'n' Greases, November 1996, p. 16.
Lemmon, Margaret, Metzger, Kirk, and Taracha, John, "Impact of Base Oil Trends on Future Lubricant Formulations-The Additive Approach," NPRA annual meeting, Mar. 16-18, 1997, San Antonio.
Hairston, Deborah W., "Slip Sliding in Lubricants," Chemical Engineering, October 1996, p. 65.
Sztenderowicz, Mark, and Lok, Brent, "Base Oils to Meet Future Lubricant Requirements: ILSAC GF-3 and Beyond," NPRA annual meeting, Mar. 16-18, 1997, San Antonio.