Preparation of homogeneous gas mixtures with SF.sub.6

Details Preparation of homogeneous gas mixtures with SF.sub.6 Preparation of homogeneous gas mixtures with SF.sub.6

1999-08-03

2000-08-22

Douglas, Steven O.

Fluent material handling, with receiver or receiver coacting mea

Processes

Filling dispensers

141 9, 141100, 141 3, 2221451, B65B 104

Patent

active

061056316

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a method for the preparation of essentially homogeneous, compressed gas mixtures with SF.sub.6, and to a mixing station, particularly a mobile mixing station, which can be used for this purpose.
In principle, separate gases can be converted into a homogeneous gas mixture by transferring the gases into a container and waiting for a sufficiently long period of time, until a corresponding homogeneous gas mixture is formed by diffusion. However, since extremely long times are required for this purpose, such a method cannot be used industrially. Of course, mixing is also observed when gas streams are passed into a stationary mixer and/or into a common pipeline. In such a case however, mixing is not always so thorough, that the mixtures achieved can be considered to be "homogeneous", especially if gases of greatly different densities, such as those containing SF.sub.6, are to be mixed. Such a gas mixture is the mixture of SF.sub.6 (sulfur hexafluoride) and N.sub.2 (nitrogen). As a gas, SF.sub.6 has a density of 6.18 g/l and N.sub.2 a density of 1.170 g/l, in each case determined at a temperature of 15.degree. C. and a pressure of 1 bar absolute (normal conditions in the sense of this application). Such gas mixtures are used, for example, as an insulating gas for underground cables carrying a current. In this connection, it is a particular problem that the gas mixtures (which are required in large quantities) expediently must be prepared on site. If namely gas mixtures, pre-fabricated in a factory, are to be used, these mixtures would have to be transported in gas cylinders under a high pressure in order to keep the transporting costs as a low as possible; however, this is not possible, since a portion of the SF.sub.6 would then condense and corresponding demixing would occur.


SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method with which homogeneous, compressed gas mixtures of SF.sub.6 and other gases, the density of which is very different, can be produced. It is moreover an object of the present invention to provide a mixing station, which can be used for this purpose, especially a mobile mixing station, which can be used for this purpose. Yet another object of the invention is to provide a mixing station, which is protected against the effects of dirt and weather. These objectives are accomplished by the inventive method and/or the inventive mixing station.
For the inventive method of producing essentially homogeneous compressed gas mixtures of separate gases, one gas being SF.sub.6, and the other gas or gases having a density, which under normal conditions is at least 4 g/l below that of the SF.sub.6, the separate gases are pre-mixed with formation of an inhomogeneous gas mixture, the inhomogeneous gas mixture is passed into a static mixer and/or a buffer tank, the gas mixture is passed from the buffer tank or the static mixer into a compressor, which delivers an essentially homogeneous, compressed gas mixture. If a buffer tank is provided, a portion of the essentially homogeneous, compressed gas mixture, which is delivered by the compressor, is returned via a return line into the buffer tank.
The inventive method makes it possible to produce homogeneously mixed gas mixtures at the site of use. It is therefore no longer necessary to supply homogeneously mixed gas mixtures from the factory. It is a further advantage that high rates of flow (for example, greater than 200 Nm.sup.3 per hour!) can be handled; at the same time, the degree of mixing is independent of the cross section of the pipelines used. The metered delivery of the finished, homogeneous gas mixture is possible.
If a static mixer and a buffer tank are provided, it is advantageous to pass the gas initially through the static mixer and then through the buffer tank.
In accordance with a preferred embodiment, the method is carried out using a buffer tank, and a control valve is installed in the return line. With this control valve, the return of a portion of th

REFERENCES:
patent: 4734371 (1988-03-01), Schmolke et al.
patent: 5137047 (1992-08-01), George
patent: 5356533 (1994-10-01), Nakagawa
patent: 5451104 (1995-09-01), Kleen et al.
patent: 5904190 (1999-05-01), Patel

Affiliated with

Also associated with

Rating

Preparation of homogeneous gas mixtures with SF.sub.6 does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Preparation of homogeneous gas mixtures with SF.sub.6, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of homogeneous gas mixtures with SF.sub.6 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-569852