Gas-to-liquid Synfuel Technology steps Closer to Commercialization
Texaco, Brown & Root and Syntroleum Corp. announced on Dec. 10 an agreement to develop a 2,500-bbl/d gas-to-liquids (GTL) plant using the Syntroleum process. The proposed plant will be a modular design to be located outside the United States at a site to be announced during the first quarter of 1998.
The plant's design will incorporate the new HMX (hybrid multiphase technology) Fischer-Tropsch reactor that has been developed under a joint development agreement between Texaco and Syntroleum, with technical support from Brown & Root and Bateman Engineering. The 2,500-bbl/d plant will be capable of converting natural gas into light and heavy syncrude, which can be further processed into petroleum products.
Purchase orders are expected to be issued in the near term for items that could impact the plant's scheduled start-up during the third quarter of 1999. Brown & Root will act as the engineering procurement and construction contractor. Texaco will provide operating, process and technical expertise. "We are excited to get our first GTL project underway and expect to be incorporating Syntroleum's GTL technology into various locations worldwide as an additional means of adding value from Texaco's global gas reserves,'' stated Graham Batcheler, an executive at Texaco Global Gas and Power. Coincidentally, Texaco Chairman and CEO Peter I. Bijur mentioned the project as part of Texaco's "aggressive efforts to revitalize downstream" in coming years, during a presentation before security analysts in Harrison, N.Y., on the same day as the Syntroleum announcement.
A Dec. 4 announcement designated Brown & Root as an Approved Process Design Provider to provide technical assistance, design support services, and process design packages to Syntroleum, a relationship shared with Bateman Engineering, another engineering company. Brown & Root is also the Approved Engineering Contractor, providing screening studies, project, technical and economic evaluations, feasibility studies, and engineering, procurement and construction (EPC) services to Syntroleum licensees and prospective licensees. Two other engineering companies, Bateman and recently added AMEC Process and Energy Limited, provide similar services as Approved Engineering Contractors. Execution of this agreement expands the terms of the original agreement announced in February 1997.
"We expect that this will be the world's first economical GTL plant," stated Mark Agee, Syntroleum's president and COO. "We are delighted that Texaco, our first licensee, has taken the lead with Brown & Root to move the Syntroleum process forward to a commercial plant.'' Syntroleum has been working on the technology since 1984, built a 2-bbl/d pilot plant in Tulsa in 1990, and a second-generation unit in 1996. It has also licensed the process to Arco, Marathon and YPF S.A., Argentina's largest oil company.
Something of a GTL race is developing. Sasol Ltd., the Johannesburg, South Africa, energy and chemical company, has been running large syngas projects for years, due to the country's former condition as a non-importer of petroleum. Exxon Corp. (Irving, Texas) has developed a slurry bubble-column reactor called AGC-21, and is investigating a project in Qatar. And Shell International (London) has had a "Middle Distillate Synthesis" process, which has been in commercial use since 1993 in Bintulu, Malaysia, where it converts natural gas into fuels and specialty chemicals.
New-Generation Fischer-Tropsch
The Syntroleum process updates traditional syngas chemistry, using natural gas as a feedstock (Figure). Gas is reformed to syngas via a catalyzed reaction with air, producing a stream rich in hydrogen and carbon monoxide. The next step, the Fischer-Tropsch (F-T) synthesis, uses another catalyst to produce hydrocarbon chains (liquid fuels). The resulting syncrude is in the middle-distillate range (diesel, kerosene or naphtha), which can be upgraded via conventional hydrocracking.
The Syntroleum process (simplified) features a syngas reactor and the Fisher-Tropsch reactors. The lack of an air-separation system and a syngas recycle simplifies the process and improves economics
Besides the HMX reactor that Syntroleum will use in the latest project, the company has experimented with fixed-tubular and fluidized F-T reactors, and a fixed-bed horizontal design. It has also concentrated on F-T catalyst development, and claims to have a viable "chain-limiting" catalyst that optimizes the synthesis reaction in the middle-distillate region.
The process's economics are helped by avoiding air separation (i.e., oxygen liquefaction) and steam—the traditional reactants for syngas—while using air in an "autothermal reformer" that it has developed. Nitrogen buildup, a problem with closed-loop air-syngas reactors, is also avoided. In addition, the hydrocarbon-synthesis step produces water and waste heat. A 10,000 bbl/d unit, says Syntroleum, can produce 15,000 bbl/d of clean water and 50 MW of electricity. However, these technical innovations are minor compared to the key to Syntroleum's business plan: the use of "stranded gas." Such gas occurs is natural gas reservoirs that are too small, or too remote, to justify pipelining or the construction of LNG facilities. More than 40 percent of the world's gas fields, holding 95 percent of the world's gas, can be utilized economically by a Syntroleum unit producing less than 50,000 bbl/d over a nominal 30-year plant life. The production unit can be built in a small, modular unit, and installed on a barge, or at a pipeline gathering gas from a remote field. Syntroleum can even lay claim to displacing some carbon dioxide greenhouse-gas emissions, since much stranded gas is simply flared, especially gas associated with oil production.
The companies making the Dec. 10 announcement did not indicate where the 2,500-bbl/d unit would be installed, nor what it would cost to build. But Syntroleum literature offers a range of capital costs that trend downward as capacity goes up (2,500 bbl/d is the minimum size). A recent study it performed found a cost of $97million, fully installed, for a 5,600-bbl/d unit. In any case, Syntroleum's goal is to produce fuel-grade syncrude at around $20/bbl.
Syntroleum Corporation, 400 South Boston, Ste. 1000, Tulsa, OK 74103. Tel: 918-592-7900; Fax: 918-592-7979
By Nick Basta