Morphysorb^® Accepted for Commercial Application

GTI and Uhde jointly developed the Morphysorb^® physical solvent acid gas removal process over the past decade with funding assistance from Gas Research Institute (one of GTI's predecessor organizations), the U.S. Department of Energy—National Energy Technology Laboratory (DOE-NETL), and GTI's Sustaining Membership Program. The process uses N-formyl and N-acetyl morpholine mixtures to remove acid gases (H₂S and CO₂) from natural gas. The process has a number of advantages over competing physical solvents, particularly higher acid gas absorption capacity and lower absorption of light hydrocarbons (e.g., methane and ethane). These features result in lower pumping energy costs, lower compression horsepower for flash gas recycle, and smaller equipment. The process was extensively tested in VLE and bench-scale units at GTI and in pilot plant equipment at a host site in south Texas. Data from these tests was modeled with advanced chemical process simulators.

In March 2000, GTI discussed with Westcoast Energy, Inc., the use of Morphysorb in a plant which was then on the drawing boards. The risks of using a new solvent in the plant were deemed too high to undertake at that time, but the process was evaluated by Westcoast again in late 2001. By that time the plant had been designed for a competing solvent and was under construction. GTI and Uhde were again contacted about the possibility of using Morphysorb in the plant. GTI recalculated the expected performance of the process using the site-specific details now available. Westcoast's economic rationale had shifted, and the enhanced performance available by using Morphysorb was sufficiently attractive to pursue its use again.

At a critical meeting in January 2002, GTI and Uhde presented the project to a large group of Westcoast staff who were stakeholders in the project. Westcoast Energy was acquired by Duke Energy Gas Transmission Company around this time.

Plant and Project Description
The plant—the Kwoen Sour Gas Upgrader, near Chetwynd B.C., Canada—is designed to treat 300 MMscfd of natural gas with approximately 25% acid gases (H₂S and CO₂ in roughly equal amounts). About 33 MMscfd of acid gases are desired to be removed (about 1/2 of the total), and the sweetened (but still quite sour gas) is sent to the Pine River Gas Plant, where the remainder of the acid gas is removed and sulfur is recovered. Removal of the acid gases at Kwoen was found to be the cheapest way to process the additional gas coming onstream in the area. Acid gas at Kwoen is reinjected downhole. Details of the plant and project can be found in the paper, Performance of Morphysorb® Solvent in a Commercial Acid Gas Treating Plant, (pdf 962 kB), by Glenn Kowalsky of Duke Energy Gas Transmission Company, and others (presented at the 2003 Laurence Reid Gas Conditioning Conference, Norman, Oklahoma, February 2003).

The plant consists of two large (~8 ft. diam.) contactors, each sized to process 150 MMscfd of natural gas and operating at 1000 psi. The Morphysorb liquid, laden with acid gas, goes to a series of four flash drums in series. In the drums, the pressure is let down progressively, releasing the contained acid gas. Some of the acid gas (that from the first two contactors) is recompressed to the absorbers, and the remaining flash gases are recompressed to injection-well pressures and flowed downhole. The solvent, substantially free of acid gases, is returned to the absorber by pumps. For details on the process in general, visit the Uhde website and view articles on Morphysorb^® under Oil and Gas.

GTI's Role
GTI is the process co-developer and funder (through GRI) of the project and has responsibility for solvent provisioning, process training for plant staff, and the conduct of an acceptance test that will demonstrate a number of important, contractual performance warranties, which deal with issues such as:

• solvent loss
• light hydrocarbon losses
• and acid gas removal capacity.

A 72-hour period of steady operation has been agreed to as sufficient to address these metrics. DOE-NETL, a cofunder of earlier development work on the Morphysorb process, is funding the preparation of a non-proprietary, public-domain report of Morphysorb's performance in this first commercial-scale application. GTI set up a laboratory at the plant site to perform key analyses in near real time, such as Karl Fischer and GC analyses. GTI further designed sample stations to enable the safe collection of the high acid gas content gases at various locations in the plant. Before plant startup, GTI also performed critical tests of various materials used for gaskets, seals and O-rings to ensure compatibility with Morphysorb. GTI evaluated the effect of elemental sulfur (which is present in the feedgas) on the solvent, and GTI and Uhde carried out numerous simulations and checks of performance for various off-design and startup scenarios.

Field Test Results
The plant has progressed through various stages of startup since mid-August 2002. Startup issues were unrelated to the Morphysorb process performance and involved reinjection well performance, compression, and mechanical issues. Nonetheless the plant has been able to feed gas at up to approximately 100 MMscfd, in one contactor, more or less continuously, through the end of September. In October 2002, several fixes, repairs and improvements were made to enable full capacity testing. Acceptance testing began in early November 2002, and proceeded according to plan. Approximately 54 hours of steady operation at two distinct operating points was achieved. GTI collected gas and liquid samples and carried out on-site analyses. A few additional samples were collected for analysis at GTI's Des Plaines laboratories. A single contactor was operated at the target rate of 150 MMscfd and at the target circulation rate. GTI prepared a proprietary Acceptance Test Report and submitted it to Duke Energy management for review. In early December 2002, Duke Energy reviewed the GTI report and then formally accepted Morphysorb for continual, commercial use at the Kwoen Plant. No foaming or other solvent-related upsets have occurred. Up to 20 MMscfd of acid gas (CO₂ and H₂S) has been rejected from the natural gas and injected downhole.

Preliminary performance at partial throughput has also been well within expectations, based on extrapolation using the simulator. No foaming issues or plant upsets due to Morphysorb have been observed. Approximately 15 Bcf of natural gas had been processed in the plant as of February 2003.

Ready for Commercialization
The Morphysorb process has been thoroughly tested and developed and now is in the early stages of commercial use. The risk of applying Morphysorb has been greatly reduced at this point, and its adoption may now be justified, based on its superior performance capabilities in many applications. GTI and Uhde are ready to evaluate additional applications for customers, and Uhde is ready to provide a license to use the technology commercially. For applications of Morphysorb outside the envelope of what has been tested and proven, additional commercial-scale field experiments can be evaluated.