Distributed Generationthe Fuel Processing Example

Richard A. Victor Praxair, Inc. Tonawanda, New York 14151

Paul J. Farris Valerie Maston International Fuel Cells Corporation South Windsor, Connecticut 06074

The increased costs of transportation and distribution are leading many commercial and industrial firms to consider the on-site generation for energy and other commodities used in their facilities. This trend has been accelerated by the development of compact, efficient processes for converting basic raw materials into finished services at the distributed sites.

Distributed generation with the PC25™ fuel cell power plant is providing a new cost effective technology to meet building electric and thermal needs. Small compact on-site separator systems are providing nitrogen and oxygen to many industrial users of these gases. The adaptation of the fuel processing section of the PC25 power plant for on-site hydrogen generation at industrial sites extends distributed generation benefits to the users of industrial hydrogen.

Industrial hydrogen, although handled in laige quantities at refineries, is used in much smaller quantities by nearly all basic industries throughout the world. Presently, hydrogen typically is produced in large plants where substantial and dependable long-term volumes of low-cost feedstock are available from established production processes in heavily industrialized areas. Most customers use hydrogen in the gaseous state. Local low-volume users can get gas delivered in tube trailers which normally operate at ranges less than 200 miles. For the larger volume users and for longer distances, there has been a cost advantage in producing, delivering and storing liquid and converting it back to gas at the point of use. Liquefaction is energy intensive and thus represents a substantial portion of the cost of delivering hydrogen.

Typically, distribution represents more than 30 percent of the overall cost of delivered hydrogen. Therefore, there is considerable incentive to develop low cost, compact systems for on-site hydrogen generation.

Praxair and International Fuel Cells Corporation (IFC) have designed and are marketing small on-site hydrogen generators with capacities of up to 25 million standard cubic feet per month (708,000 cubic meters). A flow schematic of the hydrogen generation system is shown in Figure 1. The plant incorporates a steam reforming system incorporating fuel processing equipment and technology from IFC's PC25 power plants, and compression and hydrogen purification systems designed by Praxair. The purification offgas is recycled to the reforming system to provide energy for the reforming process.

Figure Is Hydrogen Generation System Schematic

The hydrogen generation plants are modular in design and can be scaled to have rated output capabilities ranging from 5,000 to 25,000 standard cubic feet per month. Other features of the plant are listed in the Table. The design features such as automatic, unattended operation, high reliability and low maintenance provide favorable economics for on-site hydrogen generation. The plants are projected to have a significant cost savings over liquid hydrogen deliveries presently used to meet this need.

Table

Hydrogen Generation System Features

• Five plant sizes, from 6,000 to 30,000 cubic feet (160 to 800 cubic meters) per hour

• Compact plot requirements from 1,800 square feet (170 square meters)

• Standard modular design

• Hydrogen purities up to 99.999 percent

• Delivery pressure as needed

• Natural gas or propane feedstock

• Skid-mounted portability

• Automatic, unattended operation

• Low emissions

Two hydrogen generation plants incorporating these technologies are scheduled to begin operation in 1996. Figure 2 shows the first reformer skid being shipped from IFC's facility in South Windsor, Connecticut. This pallet is 10 ft. by 36 ft. and incorporates five (5) PC25 fuel processing units, and a control system which communicates with the overall plant controller to provide start-up, shutdown and normal operation of the reformer section. The control system automatically adjusts the hydrogen rich Syngas output in response to signals from the overall plant controller.

The Syngas is then compressed to feed a pressure swing absorption system which removes impurities, yielding a gaseous hydrogen with a purity level up to 99.999 percent.

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