DE1939087A1 - Steam vacuum pump - Google Patents

Description

United Kingdom Atomic Energy Authority, London, UK

Steam vacuum pump

The invention relates to vapor vacuum pumps in which & aa Fluid to be sucked into one or more steam jets (en) is diffused in at high speed or is carried along by these and in this way transported in the desired pump direction and in the direction of the The outlet side of the pump is compressed, the invention concerns especially the vaporizer and steam generation » Devices for such Daiapf-Vakaiampumperi.

It is characteristic of the conventional steam vacuum pumps that the pre-steamers, in which the working steam is generated, require a considerable amount of time to reach the operating temperature when the pumping operation is to commence, and the resulting temperature Longer than the start of pumping can be extremely undesirable . It is also inherent in certain conventional vapor vacuum pumps that the working fluid flow may be impaired if air at atmospheric pressure enters the evaporator of the pump while the evaporator and

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its content still changes after a period of pumping operation are at the operating temperature. For the reasons mentioned above, it is common to use D ^ mpf vacuum pumps or to equip your evaporator with valve systems, by means of which the whole pump, or at least the evaporator part the pump, - disconnected at operating temperature can be, in such a way that the apparatus from which is pumped will be placed under atmospheric pressure can, as soon as this is desired, without either the The pump's evaporator is cooled by air before the inlet k or the evaporator of the pump to be reheated needed if the connected apparatus is evacuated again shall be. Such valve systems are expensive and, moreover, often very eperrigo

Another part of some conventional vapor vacuum pumps is the need to use large evaporators with a large amount of work fluid (which can be an expensive material).

Furthermore, there is also the risk of periodic boiling surges during evaporation, so that the output and speed of steam generation and, correspondingly, the evaporation pressure generated may vary over time.

The invention is intended to create a damping vacuum package of the type mentioned at the outset, at walcher the named Hachtelle of the known pumps are avoided.

For this purpose, a steam vacuum package according to FIG Invention provided that for the evaporation of Arbeitscströmuagsmittel sin electrical resistance heating element

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is provided which consists of a porous resistance material consists, through the pores of which the working fluid to be evaporated is diffused.

The applicability of the invention is not limited to single-stage steam vacuum pumps and also not to steam vacuum pumps -rom ⁿ Xondenaations ⁿ -type, in which the work fluid is condensed when it first contacts the pump housing after exiting the nozzle.

Bas according to the invention provided heating element of the evaporator consists of a porous material, the pores of which communicate with each other and have a controlled size, and therefore have a high internal surface area having. Such a heating element is heated by applying an electric current and at the same time se iae porous material structure of that to be evaporated. Fluid flows through it so the heat transfer can take place the fluid due to the very large contact surface with only a small temperature drop at the Interface between solid and fluid take place. The fluid can during its passages duroh the porous heating element is heated and vaporized »in such a way that it emerges from the porous heating element in the form of a steam suitable for pumping operation emerges. In some In cases it is advantageous to have a porous element on the side of the porous element through which the liquid enters To apply a layer of an electrically insulating material, so that there is no electrical heating however, ensures that the liquid enters the porous structure before evaporation occurs »The exceptionally good heat transfer conditions inside of the porous heating element allow the use of a

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Element of relatively small size, volume and smaller Mass, based on the extent to which steam is generated. this - In connection with the direct heating of the element by the electrical current passed through it - enables the simple achievement of the for the operation of a Pump according to the invention desired rapid heating-UQd-cooling cycles.

The evaporative heating element according to the invention is generally small compared to the volume of the pump; For example, all evaporator elements can be cylindrical Sleeve of 3 l / S "(approx. 7.5 cm) length, 2" (approx * 5 cm) inside * diameter and 3 1/2 "(approx. 7.5 cm) outer Durohmeseer serve. Dae means that the evaporator element according to the invention can be housed in a housing that on or is arranged partially or entirely within the pump housing, whereby the structure and in particular also the Arrangement for the supply of the working fluid both to the evaporation element as well as from the element to the The pump is much simpler.

The minor hassle of the vaporizer element according to the invention and the required amount of co-fluid to be heated means also that the pumping operation can be started and ended very quickly.

In the following, examples of the invention are described with the aid of the drawing.

Flg.l in a schematic vertical view of a single-stage electric steam jet vacuum pump according to * ■■ an embodiment of the invention.

Pig. 2 one of the top half of Pig. 1 corresponding view a two-stage pump.

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Pig. 3 shows a corresponding payout for a single-stage horizontal pump.

4 shows a two-stage pump in a schematic side view.

The Flg. Figures 5 and 6 are schematic views of two types of diffusion pumps according to two embodiments of the invention.

Pig · 7 Ib aohematlsoher view «in © Dampfstr & hlpaap · genää an embodiment of the invention.

In the case of the in Flg. 1 finds a sluggish, oily pump Liquid as a working fluid use} the Liquid is evaporated in a steam generator unit 11, and the steam is fed to a nozzle 12, which has an all · » common in the pumping direction along the axis 13 of the main pump housing directed diverging steam jet generated at high speed. The gases to be pumped from the inlet opening 14 mix with this steam jet and are carried away by it and through the - "pump housing transported in Riohtung on the outlet opening 15 and compressed. The working steam finally hits on the cooled walls 16 of the pump housing and condenses to these; from there it flows back in a liquid form into a storage container 17 of the working fluid. The pump usually works in series with a primary vacuum pump, to which the pumped gases are fed from the outlet opening 15 for further compression and release to the atmosphere.

The evaporator has a porous element 18 in shape a thick-walled, on seinegt. End face of open cylinder which is carried by electric current in the axial direction

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will flow. At one end of the cylinder the cylinder is closed by a clamping plate 19 which is connected to an electrical supply line 21; at the other end, the interior of the cylinder is connected to a steam line 22 leading to the nozzle 12. Liquid is sucked into a housing 23 surrounding the element 18 via a supply line 24 which is connected to the storage container 17 via a measuring pump 25. The liquid is blown through the metering or furderpuap at a controlled speed through the feed line. Ataotnea and flows inward through the porous wall of the element 18; The liquid is evaporated in the wall in such a way that steam in a suitable quantity and at a suitable pressure for supplying the pamphlet nozzle 12 emerges into the steam line 22. Controlled overheating can also be provided. The nozzle creates an effective jet of steam to operate the pump, as explained above.

The fluid reservoir is conveniently under the outlet end of the pump arranged in such a way that the Working fluid flows back into the reservoir after condensation. The working fluid is in the storage tank at a temperature that is only moderately above the cooling water temperature. the The metering pump 25 (which can be arranged inside the storage container) continuously withdraws liquid from the storage container when the Vaktauw pump is in operation and thus ensures a constant supply of liquid to the porous evaporator element.

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It is readily apparent that when commissioning dei ^ umpe of the evaporation element 18, its thin-

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walled (tohäua © 29 and the Sampfdttse 12 formed small thermal hatred can be brought up to operating temperature quickly. The main reservoir 17 for the Operating flow means and the liquid contained therein as well as the supply line 24 to the dttsenbereioh do not need to be heated to the evaporator temperature · You electrical hot energy is fed directly to the evaporator element, in such a way that it is heats up extremely quickly. To end the push forward only the electrical current supply ■ α dea test steam element «obe retained. You feed cool working fluid from the storage container can be continued for a short time; it causes rapid cooling of the evaporator element and the directly arranged housing to an external safety temperature for the admission of atmospheric air. Alternatively Irann Si® PurdermeSpunpe 25 shut down (and if necessary »fall in desired for a few seconds reverse PCrderrichtung be operated so that they pump working fluid from the area of the porous evaporator unit). If you proceed in this way, the porös® Yerdampfereleaent and the hot surfaces on the surface are exposed very quickly of the working fluid, so that there is no working fluid is at a high temperature, which could be impaired or reset if atmospheric air enters. In this way, the invention makes them very quick Working or operating cycles without the use of a system Sound separation valves allows.

The storage tank, the FöräermeSpump and the porous element form a much lighter and more compact one Unit than otherwise for the generation of steam with comparable

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Able Gesohwiadigkeit when using: a conventional Evaporator units would be required. So it has in Pig. 1 shown evaporator element 18 has a length of only about 3 1/2 "(about 7» 5 cmK

The inventive method of generating steam by means of heat transfer within the body of porous material "such that a controlled conveyed liquid stream is transferred by heat transfer with a very large surface Koηtaktfläche into steam, the unregelaäSige, shock, evaporation is avoided, as at the free surface a liquid reserve can occur.

It is possible to use several nozzles of a multi-stage pump To supply steam which is generated in porous evaporator elements which are arranged immediately adjacent to each nozzle, the liquid supply to the various evaporator elements by separate conveying meters (one for each evaporator unit) takes place,

which take the liquid from a central storage container. Alternatively, two or more nozzles can be used also from an evaporator containing a porous element. unit are supplied.

Fig. 2 shows a two-stage pump in which nozzles 31 ^ and 32 of a first and second stage, respectively, of a porous _Vaporator element 18 are supplied. The nozzle 31 of the The first pump stage receives steam through radial openings 33 in line 22, while line 32 is the second Pump stage supplied the steam directly from the tube 22 receives. The Fig. 2 also shows an alternative, however

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largely similar branch of attachment and bracket dee elements 18.

Of course, it could also be provided that the Liquid is supplied to the element from the inside and the vapor is removed from the cylindrical outer surface.

fig. 3 shows a single-stage horizontal pump with a similar 7-evaporator element 18. Corresponding ropes are included denoted by the same bosses as in FIG and a separate description of this example does not appear to be necessary »

A pump according to this exemplary embodiment could, for example, be used as the third stage of a three-stage pump by having the inlet opening 14 with applied to the outlet of the two-stage pump according to Pig · 2 · The metering pump 25 could also come from the Convey sump or gate container 17, and the sump * or storage container 17 'of the third stage could over a drain line with the sump or reservoir 17 of the first and second stages must be connected.

Alternatively, it is possible to use the various nozzles in one multi-stage pump each separate from their own To supply porous evaporator elements, these evaporator elements being fed with liquid by separate feed pumps from separate storage containers. In this way, a multi-stage pump can be created in which different pumping fluid to the Operation of the various pump stages can be used in such a way that to operate the stage closest to the pump inlet (which must therefore deliver the highest vacuum)

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Very low vapor pressure working fluid and to operate the one closest to the pump outlet port Stage, (which push the pumped Gee out of the pump against the highest possible back pressure must) a more volatile working fluid B medium is used would. For example, the input stage could be steam from an inert diffusion pump oil, and the output stage operated with steam of sufficiently high steam pressure in such a way that this stage can work directly against the atmospheric pressure. For those in between Medium volatility fluids can be used. Two with each other in this sense connected · separate stages are sohematiech in Fig. 4 shown. It is readily apparent that there are innumerable different arrangements and combinations of 7erdMapfer units and pump stages are possible.

Zn the Pig. 5 and 6 is application of the invention to Diffusion pumps illustrated. Such pumps can work with very low evaporator pressures, eo dag it It is possible (and in some cases desirable) to design a diffusion pump in such a way that a Metering pump for supplying the working fluid to the Evaporator becomes dispensable. The gate parts are very quick to heat up and very quick to cool down with these Use cases often less important than the benefit ' of shock-free vaporization.

Figure 4 shows a two stage diffusion pump with one 7 evaporator element 18 according to the invention, which is in the vicinity of the lower end of the pump and connected to the working fluid is supplied via a line 41, which supplies from an annular space 4-2, in which the condensed working fluid is after the drainage collects on the cooled pump wall 43

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In the supply line 41 is adjustable by means of a Control valve 44 to a suitable liquid flow adjustable with the evaporator unit.

Damped fluid rises in a steam pipe upwards and is moved downwards against the walls by means of deflection devices 46 of a first and second stage of the condenser, which are cooled by cooling coils 47, in such a way that a stream of condensed liquid flows back into the sump or storage container 42 can. According to the well-known principle of a diffusion pump including the condensing flow of gas from the pump inlet 14 with, the one connected to the pump outlet 15 Backing pump can be pumped out.

Figure 6 illustrates a similar type of pump, however with a Tssdaspfereleaent 49 of disk shape, in which the electric current flows in the radial direction. The evaporator element is arranged in the lower part of a bell-shaped evaporator cover 51, which has cavity walls 52 to control the heat transfer. The evaporator cover carries a steam pipe 45ι in which the steam flows up to the pump nozzles 46. This The evaporator is initially charged with liquid which has the R-> by 53 in the housing below the evaporator element

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fills and saturates the evaporator element in such a way that this is almost completely immersed in the liquid * During operation, you quickly see a state in which the inside of the bell-shaped evaporator hood 51 vapor pressure generated by a column of liquid 54 standing outside the bell-shaped evaporator cover is kept in equilibrium, which · is continuously from steam condensate supplemented on the cooled walls 43 of the pump housing flows downwards. The. arrangement can be such that a large part of the The working fluid stored in the pump is in the area of this standing when the pump is in operation Liquid column is located. During operation of the pump occurs hence the liquid continuously τοη down in dee disk-shaped porous evaporator element and is baiBDttrohwBQdera dee element · rerdaapft.

. ? ig. 7 shows a steam jet point according to a floodplain leading to »- form of the invention «Too the steam eleaent 18 generated Baapf is beaohleanigt through the nozzle 55, and air as well Moisture (or some other flow to be pumped * medium) sound 14 is produced in a combined sonic biffusor unit 56 for compression and delivery.

For the sake of simplicity and clarity, in d «n last figures of the drawing the measures only electrical power supply not shown

In general, the electrical power supply can τοllotentially in done conventionally. The voltages used in each case only have to be such that electrical discharges are in Termieden inside the vacuum pumps.

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Certain features in connection with diffusion pumps have been described as an introduction; however, these various characteristics can also apply to vapor vacuum pumps in general Find application.

- patent claims -

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Claims (8)

^: . ■■■. "..; - Ή -." ■.: ■. ■■ '. ■. Claims Vapor vacuum pump, in particular a fusion or vapor pump, with a work fluid to be vaporized. characterized in that an electrical resistance heating element (18) made of a porous resistance material is provided as the evaporator, through the pores of which the working flow medium to be evaporated diffuses. 2. Pump according to claim 1, thereby ge k β η η ze i ο h α e ty * that the evaporator Helaelement in the form of a cylinder Maa tele is trained. 3. Doll according to claim 1, as a result, I do not know that the evaporator heating element has to be blinded in the form of a disk . 4. Puspe after 6iaem or more of the preceding Aneprüohe, in multi-stage execution, thereby g e k β η η ζ e i c h η θ t » that each stage - a separate own evaporator hot element having. 5. Pump according to one or more of the claims 1 "to 3 _f in a multi-stage design, characterized in that that a single evaporator element causes the supplies medium for all levels (Flg. 2, 5 and 6). ■ "■ - ^: - .-: ■■■■■," ■ - · ■ -. -.15-- "- ■■■■: ■■■ ■ 000835/1200 - 15 - 6. Puap «according to one or more of the preceding Expectations" characterized, the dae or each of the evaporator heating elements on wire in the pump housing is arranged. 7. Pump according to one or more of the preceding Expectations, characterized, da8 the evaporator heating element is small compared to the volume of the lamp housing. 8. Pump after an ode? several of the. previous Expectations, thereby gekeoßs®.wages, dmS da · T @ räaspfer-Heisel «» at himself aa S-Bingangseade ·· alt dtr Pumpefuf © wmibnnüenmn Ihapfronree is located. 9 »Puap» RÄofe & in <m Q & m: ^^> ^ :: · οη 4er Torh »rgeh« odea sprüoh «, in Auebilauog as diff osionspusp ©« tedoreh g % k ο η α s β i ο 3 & η et, da8 at End · tor Pnapkunicr «lae Sa3Be« 13 »s» es? for da · Ar beltsetröaungeaittel is provided, the »it Atm Mittelelngang de «Evaporation is connected. 009835 / 12C0