Friction stir welding, which does not require consumables or shielding gases, is being used to join large aluminum panels for offshore use. [9,258 bytes] Each time a generation of scientists feels they have uncovered the full catalytic potential of all possible chemical combinations, up pops a new one. And, each time the expense of developing and using a new catalyst is considered to be too great, new methods are found to make it economic. Researchers in the petroleum industry, who have many

Leonard Le Blanc

Debonding, converting combustion effluents may be final solution

Each time a generation of scientists feels they have uncovered the full catalytic potential of all possible chemical combinations, up pops a new one. And, each time the expense of developing and using a new catalyst is considered to be too great, new methods are found to make it economic. Researchers in the petroleum industry, who have many achievements in catalyst development, may soon have the challenge of a lifetime.

Aided by the global warming discussion, the environmental community is making substantial inroads in persuading the public that renewable energy forms must be expanded and oil and gas combustion reduced. The touted incentive is to reduce carbon dioxide and other effluents generated by oil and gas combustion, which the environmental community insists is related to global warming.

Unless there is a breakthrough in disproving the relationship, it appears the petroleum industry may be forced to deal with carbon dioxide effluent in some fashion. Solutions appear to be twofold - converting carbon dioxide into a benign compound or debonding the effluent into primary elements, carbon and oxygen.

An ideal situation would be to convert the gas into a more complex product, but that product would require containment and may be difficult to deal with on a large scale. Debonding would require carbon containment only, since the oxygen could be re-injected for combustion or vented to the atmosphere.

There is no inexpensive means of debonding carbon dioxide at this time. Breaking tough bonds (high kilocalories per mole) is not energy efficient. If the debonding process is to work, an as-yet-undiscovered catalyst or form of micro-filtration, or a combination of the two, will have to be developed. The cost of development will be huge, but the alternative is more costly, not only for the petroleum industry, but also for the automotive and power generation businesses.

The petroleum industry has been in such a dilemma before:

  • In the 1970s, researchers felt certain all catalytic possibilities had been exhausted in efforts to convert the major smog contributors in oil and gas combustion. Shortly afterward, catalytic converters were developed. Initially, they were considered abhorrently expensive. Today, they are a standard feature.
  • Only five years ago, the process of converting natural gas into liquids was feasible, but only at great cost. Today, that cost has plummeted as a result of new catalysts and changes in process.
  • Who knows what is possible, if the inducement is there.

New Statoil-MAN method could convert 90-100% of VOC

Statoil of Norway and MAN B&W of Denmark are working on a process that will bind 90-100% of volatile organic compounds (VOC) escaping during the loading of shuttle tankers and re-introduce most of the output as fuel. The process is efficient up to 70% of volume at the present, handling most propane and heavier hydrocarbons.

The escaping VOC is hydratized, which means the gas molecules of methane, propane, ethane are bound up in snow or ice - creating a frozen hydrated material. The process requires cooling only to the -30 degrees C level, and not the -163 degrees C required to liquefy methane.

The two researching organizations believe that as much as 90-95% of a shuttle tanker's bunker oil could be replaced by recovered VOC. In effect, the cleaner fuel will result in a 90% reduction of sulfur and smoke emissions, a 20-30% drop in nitrogen oxide emissions, and an unmeasured reduction in carbon dioxide. Nitrogen oxide is a key component in ozone and smog.

A system prototype will be mounted on the shuttle tanker Polyviking by the year 2000 to test the efficiency of the process. Statoil claims that sufficient fuel can be recovered from one loading to fuel a complete shuttle trip out to a North Sea field, cutting fuel costs substantially and providing an economic as well as environmental return. The cost of developing the prototype and installation aboard the Polyviking will be about NOK 65 million, but the cost of individual installations will be much less once the process is standardized.

Mineral, biological materials in optical storage and switching

The benefit of optical communications over electronics is the speed and volume of signaling. Unlike digital processes, however, the difficulty in optics is the storage of light signals until conversion into digital data and the ease of actuating processes through light-responsive switching. Inevitably, the optical signals must be slowed down and converted into analog or digital electronic signals in order to make use of optics.

Some types of storage devices, such as mechanical writing and reading devices (disks) can handle the volume, but not the speed and reliability. Currently, light signals are shunted onto short circular fiber channels for temporary storage. Both solutions wreck the efficiency of optics. Research is underway on three different processes that could solve the optics problems:

  • Researchers at the University of Munich (Munich) in Germany may have solved the storage problem in much the same way as digital storage in semiconductors. They've created an indium-gallium arsenide sandwich that responds to light by creating electron-sized holes. The holes take on an electrical charge, and can be released from storage as required. The device operates now in a cooled environment, but research is underway on sandwiches that can handle much tougher environments.
  • Researchers at the University of Cambridge (England) have developed an arsenic- selenium glass material (chalcogenide) that shrinks and expands when exposed to polarized light. The glass has anisotropic qualities. The tiny glass structures could be developed for use in light-responsive switches and actuators.
  • Research is just beginning at the University of California (LaJolla) on molecular variants of green fluorescent biological proteins, which light up when excited by a laser. The jellyfish proteins contain amino acids, which act as light-emitting chromophores. Each molecule acts as an individual light-activating source. Research is examining the development of channels on a microscopic scale to hit individual molecules in gel.

Friction welding used on aluminum panels

A new frictional welding process employing a rotating tool is being used on aluminum panels for shipping and offshore applications. Unlike previous friction welding applications which require radial, orbital, linear, or angular reciprocation to achieve friction heat, friction stir welding uses a rotating tool injected between the two work pieces. The process, developed by The Welding Institute in the UK, is ideal for aluminum and other soft metals.

The rotating tool contains a pin which is injected into the joint. As it moves along the joint, the tool plasticizes the material. No welding consumables or shielding gases are required. The key advantage of the process is that it can replace the use of large extrusion processes in the molding of panels.

Copyright 1997 Oil & Gas Journal. All Rights Reserved.

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