CN104870815A - Pumping unit for pumping light gases, and use of the pumping unit - Google Patents

Abstract

A pumping station for pumping light gases, said pumping station having: a dry-compressed first pump (12) connected to a chamber (10) to be evacuated, and said first pump (12) dry-compressed ( 12) Second pump (14) for dry compression connected. The pump station likewise has further dry compression pumps arranged in parallel or in series with these pumps. In order to avoid contamination of the light gas by providing an oil-tight pump or by providing purge gas, according to the invention it is a dry-compressed pump which is hermetically sealed with respect to the surrounding environment, This enables low process pressures to be generated in the chamber (10) to be evacuated.

Description

Pumping station for pumping light gas and use of pumping station

technical field

The invention relates to a pumping station for pumping light gases such as helium, hydrogen or isotopes thereof. Furthermore, the invention relates to the use of pumping stations for pumping such light gases.

Background technique

When pumping light gases, there is the problem that these gases flow back due to leaks present within the pump. For example, screw pumps have a gap between the helical pump element and the housing, through which gap light gases can flow back. In order to reduce the return flow of light gas, it is known to mix the light gas to be pumped with purge gas. It is also known to increase the internal tightness of pumps by using a fluid, such as oil, for the internal sealing. Pumps using purge gas and also oil seals have the disadvantage that the pumped light gas is contaminated. This leads to the fact that the gas has to be cleaned in a complex manner. Corresponding cleaning is technically difficult and expensive. This is particularly disadvantageous when the pumped light gas is recycled and is to be fed back to the manufacturing process, for example. Even small amounts of contamination with correspondingly light gases can lead to detrimental changes in the process. Small amounts of contamination, for example, are harmful when transporting the light gas tritium in nuclear fusion experiments.

Contents of the invention

The object of the present invention is to provide a pumping station for pumping light gases, by means of which pumping station achieves a high pumping capacity at low inlet pressures while avoiding contamination of the light gases. In particular, the object of the present invention is to provide a pumping station for pumping light gases by means of which a pressure of less than 100 mbar can be achieved in the chamber to be evacuated. In particular, the object of the invention is to achieve a sufficient suction capacity at an inlet pressure of 100 mbar to 0.1 mbar.

According to the invention, this object is achieved by the features of the pump station according to claim 1 or by the use of the pump station according to claim 12 .

The pumping station for pumping light gases according to the invention has a dry compressed first pump. The inlet of the first pump is preferably connected directly to the chamber or receiver to be evacuated. In particular, the second dry-compression pump is connected directly to the first dry-compression pump, ie in particular directly to the outlet to the first dry-compression pump. Dry-compression pumps are in particular screw pumps or Roots pumps, the required tightness of the pumps being achieved not by means of oil or the like but by means of high-precision production. In order to be able to achieve a low process pressure, in particular less than 100 mbar, in the chamber or receiver to be evacuated according to the invention and to additionally avoid contamination of the pumped light gas by purge gas or an oil-tight pump According to the invention, the dry-compression pump is designed to be hermetically sealed with respect to the surrounding environment. A gas-tight seal is defined here as the spatial separation of the gas mixture inside the vacuum pump from the gas mixture outside the vacuum pump. The sealing prevents ambient gas from contaminating the gas mixture to be pumped, so that it significantly affects the application.

It is therefore essential according to the invention to use a dry, gap-tight vacuum pump. The sealing of such pumps takes place without oil or frictional/sliding seals. In particular, the vacuum pump is a screw pump. The use of such pumps prevents lubricants or components of the seal from getting into the conveyed gas.

In a particularly preferred embodiment, a further third dry-compression pump is arranged in parallel to the first dry-compression pump. This third pump is likewise connected to the chamber or receiver to be evacuated. Preferably, the two dry-compression screw pumps arranged parallel to one another are then jointly connected to a second dry-compression screw pump arranged downstream. Preferably, the two outlets of the first and third dry-compression pumps preferably converge together and are commonly connected to the inlet of the second dry-compression screw pump. With this arrangement of three dry-compressed bolt pumps, it is possible to further increase the overall suction capacity at lower pressures of less than 100 bar.

In an alternative embodiment, three dry-compressing pumps are arranged one behind the other in series, so that the second dry-compressing pump is directly connected to the other dry-compressing pump. In this way, even without the use of an oil-tight pump and even without the use of a purge gas, at low pressures of less than 100 mbar, a high concentration can be achieved, especially for hydrogen and hydrogen isotopes. suction capacity.

It is obviously also possible to connect two dry-compression pumps in parallel and then arrange two further dry-compression pumps in series in the pumping direction. With this arrangement of a total of four dry-compression pumps, very high pumping capacities can be achieved, especially for hydrogen and hydrogen isotopes, at low pressures of less than 100 mbar.

In order to further reduce the pressure achievable in the receiver, it is possible, together with the last dry-compression pump in the pumping direction, ie the second or fourth dry-compression pump according to the embodiment, to provide Backing vacuum pump for pumping. The backing pump is, for example, a dry positive displacement vacuum pump, in particular a Roots pump, a claw pump, a piston pump and/or a screw pump. According to the invention, the backing pump is designed as a dry compression pump in order to avoid contamination of the light gas to be pumped.

In particular, by providing according to the invention only dry-compressed pumps and due to the disuse of purge gas, it is possible to pump light gases with high efficiency to achieve Low process pressure. Since the gas is not contaminated, complex cleaning is avoided, making it especially possible for the pumped gas to be used again, for example, in a circulation system.

According to an embodiment it is preferred that the first and/or third pump is directly connected to the chamber or receptacle to be evacuated. Furthermore, it is preferred according to an embodiment that the second pump is directly connected to the first and/or third pump. Furthermore, it is preferred that all the dry compression pumps used are designed as screw pumps.

It is especially preferred that the entire pumping station forms an externally hermetically sealed system.

With the aid of the pump station according to the invention, light gases can be pumped in a very efficient manner, wherein contamination of the gas is avoided here. Light gases are especially hydrogen, hydrogen isotopes, deuterium, tritium, helium, helium isotopes or mixtures thereof.

The pumping station according to the invention for pumping light gases can be used in particular for the compression of light gases in a pure vacuum, ie from about 0.01 mbar to ambient pressures of about 1 bar, with a sufficiently effective pumping capacity.

Furthermore, the invention relates to the use of a pumping station with at least two dry-compressed pumps, which are hermetically sealed with respect to the surrounding environment, in order to pump light gases. The pumping station used is advantageously modified as described above and in particular pumps the light gases mentioned above.

Description of drawings

The present invention is explained in detail below according to different embodiments with reference to the accompanying drawings.

The accompanying drawings show:

1 to 3 show different schematic views of a pump station according to the invention.

Detailed ways

According to a first preferred embodiment, the chamber or receptacle 10 to be evacuated is in particular directly connected to the inlet of a first dry compression pump 12 designed as a screw pump. In the exemplary embodiment shown, the outlet of the screw pump 12 is connected to the inlet of a second dry compression pump, also designed as a screw pump 14 . The outlet of the dry compressed second pump 14 can be connected to a backing pump, not shown, via other elements of the installation or via a line 16 . The two dry-compressing screw pumps provided in the first exemplary embodiment are each designed as a hermetically sealed pump with respect to the surrounding environment.

In a development according to FIG. 2 of the embodiment shown in FIG. 1 , a third dry-compression screw pump 18 is provided parallel to the first dry-compression screw pump 12 . A dry compressed screw pump 18 is directly connected to the receiver 10 . The two outlets of the screw pumps 12 , 18 converge and are then jointly connected to the inlet of the screw pump 14 . The outlet of the screw pump 14 is connected via a line 16 to the atmosphere or to a backing pump (not shown).

A further preferred embodiment of the invention according to FIG. 3 is a combination of the embodiments shown in FIGS. 1 and 2 . According to this embodiment, the receiver 10 is directly connected to the two screw pumps 12 , 18 arranged parallel to one another. The outlets of the two screw pumps 12 , 18 converge and are jointly connected to the inlet of the screw pump 14 . A further dry compressed fourth pump 20 is connected to the outlet of the screw pump 14, said fourth pump being preferably likewise a screw pump. The outlet of the fourth screw pump 20 is connected in the exemplary embodiment shown via a line 16 to a backing vacuum pump 22 which then pumps against the atmosphere.

In all exemplary embodiments, the screw pumps are provided as dry compression pumps, wherein these screw pumps are always hermetically sealed against the surrounding environment. The backing pump 22 is also a dry-compression pump, so that contamination of the light gas to be pumped is avoided.

Claims (13)

1. A pumping station for pumping light gas, said pumping station having: a first pump (12) of dry compression connected to the chamber to be evacuated; and a second pump (14) of dry compression connected to said first pump (12) of dry compression, It is characterized in that, These pumps ( 12 , 14 ) in dry compression are hermetically sealed against the surrounding environment and are not provided with a supply of purge gas. 2. The pump station according to claim 1, characterized in that, a third pump (18) for dry compression is arranged in parallel with the first pump (12) for dry compression, and the third pump is connected with the pump to be pumped. The chamber (10) is connected to vacuum. 3. The pumping station according to claim 2, characterized in that the first and third pumps (12, 18) of dry compression are jointly connected with the second pump (14) of dry compression. 4 . The pump station as claimed in claim 1 , characterized in that a further dry-compression pump ( 20 ) is provided, in particular directly connected to the second dry-compression pump ( 14 ). 5. The pumping station according to any one of claims 1 to 4, characterized in that a particularly opposite A backing vacuum pump (22) for pumping in the atmosphere. 6. Pumping station according to any one of claims 1 to 5, characterized in that said first and/or third pumps (12, 18) of dry compression are directly connected to said chamber to be evacuated Chamber (10) is connected. 7. Pumping station according to any one of claims 1 to 6, characterized in that the second pump (14) of dry compression is directly connected to the first pump of dry compression and/or the third pump The pumps (12, 18) are connected. 8. The pumping station according to any one of claims 1 to 7, characterized in that the first pump and/or the second pump and/or the third pump and/or the further pump of the dry compression are configured as screw pump. 9. The pumping station according to any one of claims 5 to 8, characterized in that the backing vacuum pump (22) is a dry displacement vacuum pump, such as a Roots pump, a claw pump, a piston pump or a screw pump Pump. 10. The pumping station according to any one of claims 1 to 9, characterized in that, the entire pumping station forms an externally hermetically sealed system. 11. The pumping station according to any one of claims 1 to 10, characterized in that light gases, in particular hydrogen, hydrogen isotopes, deuterium, tritium, helium, helium isotopes and/or mixtures thereof, are pumped. 12. Use of a pumping station according to any one of claims 1 to 11 for conveying light gases out of a chamber to be evacuated without a supply of purge gas. 13. Use according to claim 12, wherein only gas is conveyed out of the chamber to be evacuated by the vacuum pump of the pumping station.