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Flowserve and Linde Group Form JV for Natural Gas Refueling Systems Using Ionic Liquid Compressor

Flowserve Corp., a global provider of flow control products and services for the global infrastructure markets, has formed a joint venture with The Linde Group to commercialize and deploy ionic liquid compressor iKompressor natural gas and biogas refueling systems in Europe.

Called Flowserve Compression Systems GmbH, the joint venture plans to deliver at least 70 iKompressor refueling systems by 2009 to Germany, Austria, and neighboring European Union (EU) countries. The iKompressor systems are designed to reduce energy costs by up to 20% at low-inlet pressures, substantially reduce maintenance costs, and deliver high system reliability.

The demand for alternative fuels continues to increase. In order to meet customer needs, the iKompressor is designed to deliver the critical element to deliver reliable, safe service at compressed natural gas and biogas refueling systems.

— Dr Aldo Belloni, a member of the Executive Board of Linde AG

Flowserve believes that iKompressor’s ionic compressor represents an advance in technology for multistage gas compression technology. The iKompressor’s design includes two new concepts: the use of proprietary ionic liquid as a liquid piston instead of a conventional fixed metal piston, and efficient gas compression at near isothermal conditions.

Linde has been working on the use of ionic compressors for hydrogen and natural gas for a number of years. Fixed metal piston compressors, used for pressures between 200 and 1,000 bar, have many moving parts, and the guides and bearings have to have good lubrication in order to prevent wear. For a fixed-piston compressor to be efficient for natural gas of hydrogen fuel, however, the gas-side space must be absolutely tight; otherwise, lubricant could get in and contaminate the gas. To avoid this problem, Linde developed the ionic compressor.

In contrast to ordinary molecular liquids, ionic liquids consist entirely of particles with negative and positive electric charges. The ionic liquid media developed by Linde are organic salts with melting points between below 100° C. Ionic liquids have no vapor pressure; the medium cannot mix with the ambient atmosphere provided it does not reach its decomposition temperature.

An ionic liquid compressor replaces the metal piston of a conventional compressor with a specially designed, nearly incompressible ionic liquid. The gas in the cylinder is compressed by the up-and-down motion of the liquid column, similar to the reciprocating motion of an ordinary piston. Because the ionic liquid does not mix with the gas, there is no need for seals and bearings in their compressor.

Use of liquid in place of solid pistons significantly reduces the number of moving parts and frictional losses contributing to energy efficiency and low wear and tear. Station owners, as a result, can experience at least a ten-fold increase in maintenance intervals—10,000 hours between scheduled maintenance versus 1,000 hours for conventional designs, according to the partners.

Further, the gas compression is performed at constant temperature using a water-cooled jacket around the compression cylinders. Gas compression at constant temperature (isothermal) is the most efficient thermodynamic compression cycle possible. Conventional reciprocating compressors operate on the efficient nearly isentropic compression cycle. This combined effect results is designed to use up to 20% less energy consumption at low-inlet pressure.

The joint venture will be headquartered adjacent to Flowserve (Austria) GmbH manufacturing facilities in Brunn am Gebirge, a suburb of Vienna, Austria. As part of the arrangement, Linde will supply the technology, ionic liquid, and ongoing applied research and development.

In Germany, natural gas vehicles are expected to increase to two million units by the year 2020, according to the International Energy Association.

Flowserve Corp. is a leading providers of fluid motion and control products and services. The Linde Group is a world leading gases and engineering company with more than 50,000 employees working in around 100 countries worldwide.




This invention is incredible, very powerful concept indeed, I have hard time to undersatnd why the compressed gaz doesn't dissole partly in the molten salt because of the high pressure achieve, maaaybe it saturates very fast and that's not a problem , but then when the pressure goes dowm on when the piston moes back the salt should release the gaz violentely.

Very impressive indeed

Paul F. Dietz

I don't see why having the ionic liquid being saturated with the gas would be a problem. The problem they are addressing is having the liquid evaporate into the gas, not the gas dissolving into the liquid.

Roger Arnold

The Linde compressor sounds like it could be a significant development for village-scale renewable energy storage in developing countries. A near-isothermal compressor enables efficient compressed air energy storage (CAES). The Linde Technology article on the pump quotes a 20% reduction in energy compared to a conventional multi-stage compressor. That would translate to a very substantial gain in round-trip storage efficiency for a CAES system.

Henry Gibson

The trompe liquid water air compressor was invented during the Roman Empire but was reinvented and used to supply compressed air for equipment. One seems to be still working at Ragged Chutes. They have even been proposed for use in combination with gas turbine engines and compressed air storage systems.

A trompe can also be built where there is any fall of water. The pressure output only depends on how deep the down and up shafts are constructed not on the fall of water. The amount of water available and the available drop of the water course determine the energy available and the volume of air that can be compressed.

Any rich person, who has a large stream flowing through his property and wants to use renewable energy, would be well advised to have a Trompe built underneath his property by a mining contractor and use an air turbine; an extra large air chamber can be built so that compressed air can be stored to meet power peaks. There are various ways to integrate solar and wind power with the air chamber.

Directional drilling techniques may well allow the construction of small trompes from the surface alone. And this may represent a better way of getting energy from small flows without much damage to the land surface. Again high speed air turbine-generators are cheaper to build and smaller and easier to control than water turbines. They can operate at exactly 50 or 60 Hertz so no inverter is needed.

A large buried plastic pipe can conduct the air right to the house without much energy loss, so the turbine generator can be placed close to the electrical use. Any source of heat, including a wood burning stove, can multiply the electric power available from the compressed air if run through a heat exchanger before it goes to the turbine.

Trompes should have been built at any high dam that has any chance of regular overflow. The cost of building such a unit is a small percentage of the cost of the dam and the compressed air can be used in much smaller turbines. The maintenance cost of a trompe is very low, and some continued in operation for many years without much care.

In contrast to water turbines that loose efficiency, the air turbines can be placed at high elevations where there is no danger of flood damage. Fuel can be injected and burnt for higher power at a small increase in operation cost.

There are other ways to use liquids for air compression. Liquid based compressors are very highly efficient and more should have been done with them. Perhaps oxygen machines can be made more efficient for cheaper coal to liquid conversions.

For low pressure or for a low pressure stage, an air bearing turbine compressor developed by MITI seems to have the best efficiency and the lowest maintenance. ..HG..

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