Tenneco Gas has broken ground at a site near Houston for a plant that will be typical of a new breed of worldscale methyl tertiary butyl ether (MTBE) plants. Those plants will make their own isobutylene and won't be tied to a source of isobutylene from a refinery or petrochemical plant.
The Tenneco project is an example of the route gas processing companies can take to upgrade their natural gas liquids to make what Robert C. Thomas, Tenneco Gas chairman, describes as "the fastest growing petrochemical in the world."
Thomas said Tenneco expects MTBE demand in 1993 to be double today's demand, which he places at 100,000 b/d, and triple that by 1995. To meet this demand, Thomas said, another 16 plants the size of Tenneco's will be needed.
"Meeting this demand," he said, "will require monumental capital expenditures."
TENNECO'S UNIT
To supply one of two essential feedstocks, isobutylene, for its 12,500 b/d MTBE plant, Tenneco will start with butane from its adjacent LaPorte, Tex., NGL butane isomerizer and fractionator on Morgan's Point. It will isomerize butane with UOP Inc.'s Butamer process, then dehydrogenate it to 12,500 b/d of isobutylene with UOP's new Oleflex process.
About 4,500 b/d of required methanol will come from an existing Tenneco methanol unit several miles away at Pasadena, Tex.
All MTBE plants built to date have had a by-product supply of isobutylene, mainly from fluid catalytic cracking at refineries. However, the supply is dwindling and poses a limit on MTBE production unless other sources of isobutylene are developed.
Environmental rules that will keep butane out of gasoline to limit vapor emissions also free up butane to make isobutylene-at a price-and indirectly respond to other environmental regulatory demands.
Methanol is a commodity whose supply has not been considered the limiting feedstock in MTBE production. The grain ethanol industry, with its government subsidy, is eager to replace methanol and allow production of ethyl tertiary butyl ether, which in its performance characteristics is marginally more desirable than MTBE.
The only other announced MTBE plants to date following the NGL to ether route are the 4,000 b/d Coastal Chem Inc. unit at Cheyenne, Wyo. and 12,500 b/d Global Octane Corp. plant at Deer Park, Tex. (OGJ, Apr. 29, p. 40; May 6, p. 30). Both are expected to start up in 1992, as is the Tenneco plant.
Global reportedly will employ the Catofin process from ABB Lummus Crest Inc.
Only one Oleflex unit is in operation. It is dehydrogenating propane in Thailand. UOP says about a dozen more such units are in the design stage or in start-up.
The Oleflex unit incorporates continuous catalyst regeneration (CCR), which was introduced with UOP's catalytic reforming process about 20 years ago. The MTBE portion of the Tenneco plant will employ the Huels MTBE process, licensed through UOP.
Although the product volume is relatively small, such MTBE projects are costly. Tenneco says it will spend more than $165 million for the Morgan's Point project, scheduled for start-up in early July 1992. M.W. Kellogg Co. is the contractor.
Kellogg also is building the Global unit.
The Tenneco site is in a strategic location from raw materials and product movement aspects. Tenneco's MTBE will be sold mainly under long term contracts to nearby refineries, although some will go into the spot market.
The plant is across the Houston Ship Channel from the huge Exxon Co. U.S.A. refinery at Baytown. Product can move on barges or by pipeline to Tenneco storage at Mont Belvieu, Tex., the hub of an elaborate product pipeline system.
Thomas also hinted that some MTBE could be exported to Europe.
CAPTIVE MTBE UNITS
The National Petroleum Refiners Association has conducted a survey of U.S, captive MTBE capacity and its utilization.
Captive units are those built within a refinery and using isobutylene feed from fluid catalytic cracking units (FCCUS). The survey did not include merchant plants.
The NPRA survey, released May 1, showed that during 1990 all 22 captive plants in the U.S. had a capacity of 42,205 b/cd and production of 28,618 b/cd for a utilization rate of 63.3% Utilization in 1988 and 1989 was 60.7% and 66.8%, respectively.
For the 3 year period, NPRA says the capacity utilization rate was an "unexpectedly low" 63.65%.
NPRA also says the major reason for the lower utilization rate was isobutylene supply.
A few refiners also cited lack of methanol as a reason. Seventeen of the respondents listed feedstock as the leading factor.
The MTBE unit is feedstock short when the FCCU is not running at maximum rate.
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