EP3676496B1 - Liquid ring pump - Google Patents

Description

The invention relates to a liquid ring pump which is used, for example, to convey gases or to generate a vacuum.

Liquid ring pumps are usually used to convey gaseous media and usually include an approximately circular-cylindrical pump housing in which a pump wheel is eccentrically rotatable. The impeller is usually an impeller that is approximately star-shaped when viewed in cross section. A pump liquid (also referred to as "ring liquid") is also arranged in the pump housing. This is circulated by rotation of the pump wheel in the circumferential direction of the pump wheel within the pump housing and forms a liquid ring along the inner circumference of the pump housing due to centrifugal force when the pump wheel rotates at a sufficient speed. Due to the eccentricity of the impeller, the individual blades in the circumferential direction are immersed to different depths in the ring liquid, specifically the liquid ring. The gas standing between the individual vanes during operation of the liquid ring pump is thus compressed and/or displaced from the interspaces between the guide vanes as the impeller rotates due to the ever deeper immersion of the vanes in the liquid ring. This compression or displacement effect is used by a suitable design of the pump housing in order to convey the gas out of the respective intermediate space through an associated housing opening.

Since the impeller is sealed off from the pump housing by means of the pump liquid and therefore there are hardly any components that slide against one another are present, sparking during operation of the liquid ring pump can be effectively prevented and thus explosive gases can be conveyed comparatively safely. Furthermore, the pump liquid also serves as a cooling medium and, in particular, absorbs the thermal energy that occurs during the compression of the gases. This, in turn, is advantageous when conveying heat-sensitive gases.

A disadvantage of liquid ring pumps, however, is that the vapor pressure (value) of the ring liquid limits the achievable suction pressure (specifically its value). In addition, due to dynamic flow processes in the pump housing, in particular due to sudden pressure relief, a liquid-gas mixture is formed, which is pumped out of the respective intermediate space, which also contributes to limiting the achievable suction pressure value, and depending on the pressure difference, deflagration from the respective gap out or into the respective gap. For water as the ring liquid, the achievable suction pressure (value) is therefore around 30 mbar. The deflagration also leads to a comparatively high level of noise, which makes operation of the liquid ring pumps unattractive, particularly in laboratories.

The invention is based on the object of specifying an improved liquid ring pump.

This object is achieved according to the invention by a liquid ring pump having the features of claim 1. Further advantageous and partly inventive embodiments and developments of the invention are set out in the dependent claims and the following description.

The liquid ring pump comprises a pump housing surrounding a pump chamber, with a pump liquid, also referred to below as ring liquid, being filled into the pump chamber in the intended operating state. Furthermore, the liquid ring pump includes an impeller, which is arranged within the pump chamber and around a Axis of rotation is rotatable. The impeller serves to convey a gaseous working medium. The impeller has on its outer circumference a number of pumping chambers that are separated from one another at least in the circumferential direction. The conveying chambers are preferably separated from one another by partition walls that run radially to the axis of rotation or are inclined in the circumferential direction. The impeller also has an outlet opening assigned to each delivery chamber and made locally in a bottom wall of the impeller that delimits the respective delivery chamber radially on the inside for fluidic connection of the respective delivery chamber to a pressure area (also: "high-pressure area") of the pump chamber. The bottom wall in each delivery chamber is inclined along the axis of rotation (ie viewed in the axial direction) on both sides of the outlet opening, at least in sections to the axis of rotation (and preferably also to the radial direction) and runs (from both sides) in the direction of the outlet opening. In this case, the outlet opening is in each case arranged at a point in the respective delivery chamber which has the smallest radial distance from the axis of rotation.

The term “local” is understood here and in the following in particular to mean that the outlet opening is small compared to the areal extension (for example along the axial direction) of the bottom wall and thus also of the delivery chamber. In other words, the term “local” describes that the outlet opening does not extend over the entire surface of the respective delivery chamber running along the axial direction.

In addition, the outlet opening is preferably arranged centrally in the bottom wall of the conveying chamber, viewed in the axial direction.

The term “inclined” is understood here and in the following in particular to mean that the bottom wall (at least in sections) is set at an angle to the axis of rotation or - viewed in a section along the axis of rotation - has a curved course (and is therefore locally inclined).

According to the invention, the outlet opening is therefore arranged in the respective pumping chamber in such a way that - when the impeller rotates, which is positioned eccentrically to the pump housing, and thus when the corresponding pumping chamber is increasingly immersed in the ring liquid, in particular in a liquid ring formed by the ring liquid - first the to conveying working medium (in particular a gas) and then a preferably small, in particular adjustable amount of ring liquid enters the outlet opening. It can thus advantageously be made possible for the working medium to be conveyed to be expelled as completely as possible from the respective conveying chamber by the following ring liquid. Due to the bottom wall of the respective pumping chamber, which is inclined on both sides towards the outlet opening, a streamlined chamber shape is made possible, which prevents or at least reduces a (wave-like) impact of the ring liquid on the bottom wall that contributes to the formation of the mixture (in particular to the formation of foam), and rather a directed flow in Supported towards the outlet opening. In particular, the bottom wall tapering towards the outlet opening also ensures that the ring liquid "pushes" the working medium to be conveyed in front of it in the direction of the outlet opening and the risk of mixing of the ring liquid and the working medium is reduced.

Due to the above-described flow control of the ring liquid and the resulting reduction in mixture formation, suction pressures can be achieved which come particularly close to the value range of the respective vapor pressure of the ring liquid.

In a particularly expedient embodiment, the impeller is arranged eccentrically in the pump chamber (and this is preferably also filled with ring liquid) such that a liquid ring formed by the pump liquid during normal operation, particularly in the pressure area the pump chamber completely covers at least one of the pumping chambers (in particular the "last" one or also the one ejecting the working medium) in the radial direction (on the inside). This means that the impeller in the region of this delivery chamber (ie in the pressure region) dips so deeply into the liquid ring that preferably the bottom wall of this delivery chamber also dips into the liquid ring. Particularly preferably, the respective outlet opening is at least partially below the "level" of the liquid ring. As a result, it is achieved in a particularly simple manner that the working medium that is standing and compressed in this delivery chamber is completely pushed out of this delivery chamber.

The respective outlet opening is preferably arranged and designed in such a way that (preferably in combination with the eccentricity selected above and the fill level of the ring liquid) in normal operation after the working medium has been ejected, at least a small proportion of the ring liquid flowing through the pumping chamber is also ejected . This enables the working medium to be conveyed “completely” out of the respective conveying chamber in a simple manner.

In a preferred embodiment, each delivery chamber is formed symmetrically to a radial plane of the impeller, which in this case at least partially represents a mirror surface. In this case, the exit opening is advantageously arranged in the mirror surface, touching at least this mirror surface. With such a symmetrical design of the delivery chamber, the annular liquid can also flow symmetrically and thus in a comparatively ordered manner in the respective delivery chamber. Due to the symmetrical design of the pumping chamber, in conjunction with the inclined course of the bottom wall, it is possible in particular that--when the impeller rotates--the speed of the annular liquid flowing radially inward increases approximately linearly. As a result, the ring liquid can flow in the direction of the outlet opening in a particularly orderly manner and while avoiding the formation of mixtures as completely as possible. The outlet opening is at the ("geodesically") lowest point - ie at the point with the smallest radial distance to the axis of rotation - the pumping chamber.

In a further preferred embodiment, in particular in combination with the above-described symmetrical design of the delivery chamber, the inclined bottom wall along the axis of rotation is essentially (i.e. exactly or approximately) U-shaped or V-shaped. As already described above, the outlet opening is arranged in particular at the lowest point of the U or the V. The bottom wall thus runs curved on both sides to the mirror surface (in the case of the U's) or in a straight line at an angle ("funnel-like"; in the case of the V's) towards the outlet opening.

In an expedient embodiment, each delivery chamber is delimited at the front (i.e. in the axial direction) by at least one side wall (also referred to as front or end wall), preferably by one side wall each. The or the respective side wall preferably connects to the bottom wall. The individual delivery chambers are delimited from one another in the circumferential direction by the partition walls described above. The side walls preferably run in a radial direction. The side walls serve to delimit the respective delivery chamber from the pump chamber. Optionally, both side walls or at least one of the two side walls are formed integrally (i.e. monolithically) from an impeller body forming at least the bottom wall of the pumping chambers. The other side wall or alternatively both side walls are optionally designed as "side shields" or "cover plates" and placed on the impeller body.

According to the invention, the impeller has, for each delivery chamber, an inflow opening locally in one of the walls delimiting the delivery chamber, in particular in the bottom wall or the side wall or one of the side walls, for the fluidic connection of the respective delivery chamber with a suction area (or "low-pressure area") of the pump chamber . i.e. When the liquid ring pump is in operation, the working medium to be pumped flows through this inflow opening into the respective pumping chamber.

As the impeller rotates further, this delivery chamber, in particular this inflow opening, is covered, for example, by the ring liquid, so that the working medium is prevented from flowing out of the corresponding delivery chamber through this very inflow opening. Alternatively, particularly if the impeller does not dip into the liquid ring at at least one point on its circumference, the working medium to be conveyed can also flow into the impeller via the conveying chamber, which is preferably open on the (outer) circumference of the impeller. Alternatively or additionally, the working medium to be conveyed can flow into the respective conveying chamber even if one or both side walls are missing and/or if at least one of the side walls has a correspondingly shortened radial extent, even without a specifically designed inflow opening.

In particular to prevent working medium and/or ring liquid from the high-pressure area of the pump chamber (in particular through the outlet opening) from flowing back into the respective delivery chamber, in an advantageous embodiment a non-return valve, which preferably limits the delivery chamber (in particular on the outlet side), is arranged inside the respective outlet opening. This check valve is designed to open in the exit direction from the respective delivery chamber and to seal against the exit direction. Advantageously, the check valve arranged in the outlet opening (also referred to as "outlet valve") is also set up to only open above a predetermined value of a delivery pressure (or: compression pressure) within the delivery chamber. This makes it possible to specify (adjust) a pressure difference between the suction area and the pressure area in the pump chamber in a targeted manner. In addition, such a non-return valve can prevent or at least significantly reduce deflagration effects out of the delivery chamber or back into it. As a result, the noise generated by the liquid ring pump during operation can advantageously be reduced. In order to enable a particularly high degree of efficiency of the liquid ring pump during operation (e.g. when using the liquid ring pump to convey the working medium into a space which is under a pressure value that is higher than atmospheric pressure), this is in the respective outlet opening The built-in outlet valve is designed for the lowest possible pressure loss (value). Furthermore, the outlet valve preferably also has a high sealing effect. The respective outlet valve is preferably mounted in the impeller in such a way that its closing function is brought about, or at least supported, by the centrifugal force (occurring due to the rotation of the impeller) during operation of the liquid ring pump. In this case, valve springs or comparable means for closing the respective outlet valve are optionally omitted.

In a further expedient embodiment--preferably in addition to the check valve arranged in the outlet opening--a check valve which preferably delimits the delivery chamber (in particular on the inflow side) is arranged inside the inflow opening. This is designed in such a way that a backflow of the working medium (and possibly also the ring liquid) from the delivery chamber into the suction area of the pump chamber is prevented. The “loading” (ie the filling) of the delivery chamber with working medium can thus advantageously be controlled by means of this “inflow valve”. Especially with a combination of the inflow valve and the outlet valve, a particularly precise control of the loading and unloading of the respective delivery chamber is possible, preferably purely as a function of the pressure. In addition, deflagration is effectively prevented against the direction of action of the valves. The noise development of the liquid ring pump during operation is thus further reduced. In addition, a specially shaped control disc, via which the inflow and/or outflow from the respective delivery chamber is controlled by means of a specially shaped opening, can be omitted. Furthermore, it is possible to use the liquid ring pump as a compressor, in particular because there are separate flow spaces and therefore separate pressure areas within the pump chamber when the two check valves are combined. The respective inflow valve is also advantageously designed for the lowest possible pressure loss (value) in order to increase the efficiency. Furthermore, in an optional variant (comparable to the outlet valve), the respective inflow valve is mounted in the impeller in such a way that its function is supported by the centrifugal force. In particular, the respective inflow valve is here installed in such a way that opening of the inflow valve in the inflow direction is supported by centrifugal force.

The inflow valves and optionally also the outlet valves are preferably designed as diaphragm valves. In a further optional embodiment, the inflow valves and/or the outlet valves are formed by flaps, pressure-controlled valves (for example valves produced by a printing process) or the like.

According to the invention, the outlet openings of the pumping chambers open into a (preferably common) outlet chamber arranged on the impeller (in particular on the outlet side). This outlet chamber is preferably designed for the centrifugal force-related separation of the working medium from the ring liquid. This means that the outlet chamber is set up for the separation ("separation") of gases and liquids. In particular, for this purpose the outlet chamber has an outer wall running parallel or preferably obliquely to the axis of rotation and thus in the latter case approximately a hollow conical shape. During normal operation of the liquid ring pump, this outer wall rotates with the impeller, so that due to the centrifugal effect, the ring liquid is deposited on the outer wall and can flow off along it, in particular along its sloping course. The ring liquid separated off in this way is preferably (directly or indirectly via a reservoir) fed back to the liquid ring, so that it is at least not continuously reduced in size during normal operation. However, within the framework of the independent invention described above, the respective outlet chamber can also be omitted.

In an expedient embodiment, the reservoir described above also has a cooling device, by means of which the separated ring liquid is cooled before it is returned to the liquid ring during normal operation.

In an optional additional embodiment, means for supporting the separation of the working medium from the ring liquid are arranged in the outlet chamber. These means are, for example, guide vanes or, in particular, radially aligned guide disks, which promote the separation caused by centrifugal force, for example, by means of targeted guidance in particular of the ring liquid. This makes it possible in a particularly simple manner to convey a sufficiently large quantity of ring liquid through the outlet opening for the most complete possible emptying of the working medium from the respective delivery chamber, but to keep the loss of ring liquid due to mixing with the ejected working medium to a sufficiently low level to reduce. Advantageously, a device downstream of the liquid ring pump (on the pressure side) for separating the working medium from the ring liquid can be dispensed with or at least simplified. Preferably, the above-described outer wall of the outlet chamber and a drain device (or: "liquid drain") optionally used to drain the separated ring liquid are arranged in such a way that the ring liquid is guided over a gap between the impeller and the pump housing during operation and thereby acts as a gas barrier Sealing of the gap causes.

In an alternative embodiment, in particular to the outlet valves described above, the liquid ring pump comprises a control ring which can be rotated relative to the impeller and is preferably arranged in a stationary manner relative to the impeller during normal operation. This control ring closes a large number of the outlet openings of the impeller in sections against the impeller on the output side. In particular, at least one of the outlet openings—namely preferably the ejecting outlet opening or additionally also a number of the outlet openings trailing behind the ejecting outlet opening in the direction of rotation of the impeller—is open for the outflow of the working medium. To set the pressure ratio between the suction and pressure areas of the pump chamber, the control ring can be adjusted so that it releases a different number of outlet openings. The larger the number of open outlet openings, the lower the pressure ratio. Preferably, the liquid ring pump comprises in this case also an adjusting device for adjusting this control ring. For example, the control ring for adjusting the released number of outlet openings comprises two partial rings that can be rotated in relation to one another and lie one above the other with bores that form a through-opening that can be adjusted in size (by rotating the partial rings in relation to one another). Alternatively, the control ring (which in particular carries bores) (or only ring sectors thereof) can also be displaced radially or axially in order to release a different number of outlet openings. For example, the control ring also has bores of different sizes.

In an optional development of the control ring described above, the liquid ring pump includes means for throttling the suction flow in addition to this control ring. For example, a throttle, in particular a throttle valve, is arranged on the inlet side of the pump chamber to reduce the pressure value present in the suction area of the pump chamber. In this way, the delivery pressure value that can be achieved in the delivery chamber in the pressure region of the pump chamber can also be set, in particular lowered, as a result of which deflagration effects from the respective delivery chamber can advantageously be reduced or avoided.

In a particularly expedient embodiment, a poly-alpha-olefin is used as the ring liquid. As a (ring) liquid, a poly-alpha-olefin advantageously has a vapor pressure value that is significantly lower (in particular by a multiple, for example at least ten times) compared to water, so that suction pressure values in the range below 1 mbar are also possible. It is thus advantageously possible to also use the liquid ring pump described above for the so-called fine vacuum range. In addition, the poly-alpha-olefin can also have a lubricating effect and/or contribute to sealing gaps between components due to its comparatively high viscosity.

The conjunction “and/or” is to be understood here and in the following in such a way that the features linked by means of this conjunction can be designed both together and as alternatives to one another.

Fig. 1

in einer schematischen Darstellung eine Flüssigkeitsringpumpe mit Blick auf eine Stirnseite eines Pumpenrads bei geöffnetem Pumpengehäuse,

Fig. 2 und 3

in einer schematischen Schnittdarstellung II-II gemäß Fig. 1 jeweils ein alternatives Ausführungsbeispiel des Pumpenrads,

Fig. 4

in Ansicht gemäß Fig. 1 ein weiteres Ausführungsbeispiel der Flüssigkeitsringpumpe, und

Fig. 5 bis 7

in Ansicht gemäß Fig. 2 jeweils wiederum ein alternatives Ausführungsbeispiel des Pumpenrads.

The invention is explained in more detail below using several exemplary embodiments in a drawing. Show in it:

1

in a schematic representation of a liquid ring pump with a view of a front side of an impeller with the pump housing open,

Figures 2 and 3

in a schematic sectional view according to II-II 1 each an alternative embodiment of the impeller,

4

in view according to 1 another embodiment of the liquid ring pump, and

Figures 5 to 7

in view according to 2 each in turn an alternative embodiment of the impeller.

Corresponding parts and sizes are always provided with the same reference symbols in all figures.

In 1 a liquid ring pump 1 is shown schematically. The liquid ring pump 1 comprises a pump housing 2 (represented schematically as a hollow cylinder) which encloses an interior space referred to as the pump chamber 3 . The liquid ring pump 1 also includes a pump wheel 4 , which is arranged inside the pump chamber 3 such that it can rotate about an axis of rotation 6 . The pump wheel 4 is arranged eccentrically to the pump housing 2 with its axis of rotation 6 . The impeller 4 serves to convey a gaseous working medium, specifically a gas. For this purpose, the impeller 4 has on its outer circumference a number of delivery chambers 8 which are separated from one another in the circumferential direction. The delivery chambers 8 are separated from one another in the circumferential direction by intermediate walls 10 . Each delivery chamber 8 also has an outlet opening 12 which is arranged at a point in the respective delivery chamber 8 which is at the smallest radial distance from the axis of rotation 6 .

For pump operation, a pump liquid called ring liquid 14 is filled into the pump chamber 3 . By rotating the impeller 4 in a - in 1 Direction of rotation 16, indicated by an arrow as an example, the ring liquid 14 is also set in rotation along the inner wall of the pump housing 2 and forms there due to the centrifugal force an in 1 schematically indicated liquid ring 18 from. Due to the eccentricity of the axis of rotation 6 in relation to the pump housing 2 , the impeller 4 and thus also the individual delivery chambers 12 dip into the liquid ring 18 at different depths along the direction of rotation 16 . The liquid ring 18 seals the delivery chambers 8 that are open on the outer circumference of the impeller 4 (cf. partial section II-II in 2 ) and pushes the gas in the pump chamber 3 and the respective pumping chamber 8 in front of it in the direction of the respective outlet opening 12 with increasing immersion depth of the impeller 6 in the liquid ring 18 .

In order to convey the gas, in an area in which the impeller 4 only dips slightly into the liquid ring 18 (in 1 the position at about 11:00 a.m.) the gas is introduced into the pump chamber 3 via a supply opening (not shown in detail). This area is also referred to as the suction area 20 of the pump chamber 3 . In this suction area 20, the gas enters the respective pumping chamber 8, which is located in the suction area 20 at this point in time, and when the pump wheel 4 rotates due to the "rising" liquid level of the ring liquid 14 in the respective pumping chamber 8 - due to the progressive immersion of the pump wheel 4 the ring liquid 14 flows into the liquid ring 18 in a radial direction into the respective delivery chamber 8 -- pressed in the direction of the outlet opening 12 . As described in more detail below, the liquid ring pump 1 is designed in such a way that the outlet openings 12 of the impeller 4 are initially closed on the outlet side. Only in a pressure area 22 that is essentially diametrically opposite the suction area 20 and in which the liquid level of the liquid ring 18 reaches up to a bottom wall 24 that delimits the respective delivery chamber 8 radially on the inside (in 1 in the range of about 5:00 a.m.) or even radially inside exceeds (or: "covers"; cf. 2 ), the respective outlet opening 12 is open and the compressed gas can flow out of the respective pumping chamber 8 and out of the pump housing 2 via a corresponding gas guide line, not shown in detail. The outlet opening 12 thus serves to fluidically connect the respective delivery chamber 8 to the pressure area 22 of the pump chamber 3.

In 2 an embodiment of the impeller 4 is shown in more detail. In this case, the impeller 4 comprises two side walls 26 for covering the respective pumping chamber 8 at the front (or: axial end) and which in the exemplary embodiment shown are formed in one piece (ie monolithically) from an impeller body 28 forming the impeller 4 . Radially on the inside, the side walls 26 merge into the bottom wall 24, which is U-shaped. i.e. the bottom wall 24 runs in an arc along the axis of rotation 6 from two sides in the direction of the "geodetically lowest" point (ie the point with the smallest radial distance from the axis of rotation 6) of the pumping chamber 8. At this point (axially on the inside of the impeller 4). the outlet opening 12 is arranged. In the illustrated embodiment according to 2 is the respective pumping chamber 8, specifically its geometric structure symmetrical to a mirror surface 30, which is formed by a radial plane to the axis of rotation 6. A uniform flow of the ring liquid 14 in the direction of the outlet opening 12 is thereby achieved. In the exemplary embodiment shown, the outlet opening 12 is designed as a right-angled bore and thus represents a channel that first leads in the radial direction out of the respective pumping chamber 8 and then out of the impeller 4 parallel to the axis of rotation 6 on an end face 32 . On the opposite end face 34 , an inflow opening 36 is made in the side wall 26 there, which allows the gas to flow into the delivery chamber 8 in the suction area 20 . This inflow opening 36 is particularly expedient when the liquid level of the ring liquid 14 is selected in such a way that the outer circumference of the impeller 4 is constantly immersed in the liquid ring 18 .

through the in 2 The illustrated shape of the bottom wall 24 enables an approximately linear increase in speed of the annular liquid 14 flowing into the conveying chamber 8 . The arched or inclined bottom wall 24 positioned against the axis of rotation 6 also prevents the annular liquid 14 from hitting the bottom wall 24 abruptly and the development of foam (ie mixture) and noise associated therewith. The fact that the outlet opening 12 is arranged at the lowest point of the pumping chamber 8 also makes it possible for the ring liquid 14 to push the gas in front of it and in the pressure region 22 of the pump chamber 3 the gas can initially flow out via the outlet opening 12 . As in 2 indicated, in a variant for operating the liquid ring pump 1, the filling quantity of the ring liquid 14 and the eccentricity of the axis of rotation 6 in the pump housing 2 are selected such that the liquid level of the liquid ring 18 in the pressure area 22 completely covers the outlet opening 12. This makes it possible for the gas standing in the conveying chamber 8 and the outlet opening 12 to be completely expelled through the ring liquid 14 and even for a portion of the ring liquid 14 to also be conveyed out of the conveying chamber 8 . The measures described above make it possible to pump the gas out of the respective pumping chamber 8 to a negligible proportion, so that a suction pressure value in the range of the vapor pressure of the ring liquid can be achieved.

In 3 an alternative embodiment of the impeller 4 is shown. The side walls 26 are formed by plates or shields placed on both sides of the impeller body 28 (and thus produced separately from it). The bottom wall 24 is V-shaped and thus has two straight sections running obliquely to the axis of rotation 6 (ie one section on each side of the mirror surface). Consequently, the bottom wall 24 runs in section according to FIG 2 viewed like a funnel towards the outlet opening 12 . Furthermore, the outlet opening 12 , specifically its channel section leading out of the impeller body 28 , is also set at an angle to the axis of rotation 6 . This makes it possible for the annular liquid 14 to always push the gas in front of it, even within the outlet opening 12 . The risk of (turbulent) mixing of the ring liquid 14 with the gas is thus further reduced.

In an exemplary embodiment that is not shown in detail, the side walls 26 can also be omitted, in particular if the "V" of the bottom wall 24 is raised laterally.

In 4 an exemplary embodiment of the liquid ring pump 1 is shown, in which a control ring 40 serves to release the outlet openings 12 into the pressure area 22 . For this purpose, the ring body of the control ring 40 covers the outlet openings 12 on the outlet side against the impeller 4 . To release the outlet openings 12 in the pressure area 22, the control ring 40 has an annular gap 42, within which the outlet openings 12 are not covered. In order to be able to set a pressure difference between the suction area 20 and the pressure area 22 , the control ring 40 can be rotated about the axis of rotation 6 with respect to the pump wheel 4 . The more the outlet openings 12 are open in the pressure area 22, the lower the pressure difference. Optionally, it is also possible to choose between control rings 40 with annular gaps 42 of different sizes.

In figure 5 is a to 4 alternative embodiment of the liquid ring pump 1, specifically the impeller 4, shown. To control the pressure ratio between the suction area 20 and the pressure area 22 and for the targeted discharge of the gas in the delivery chamber 8 and compressed by the rising ring liquid 14, there is a check valve in the respective outlet opening 12 of each delivery chamber 8, referred to below as the outlet valve 50 , arranged. the inside 4 illustrated control ring 40 can thus be omitted. The outlet valve 50 advantageously also prevents gas that has already been expelled from the pressure area 22 from flowing back into the already discharged delivery chamber 8 or even deflagrating back into this delivery chamber 8 as the impeller 4 rotates further and the liquid level of the ring liquid 14 decreases. This increases the efficiency of the liquid ring pump 1 and effectively prevents the development of unwanted noise. Due to the outlet valve 50, each pumping chamber behaves in isolation like an oscillating positive displacement pump (where the liquid ring 18 locally forms a liquid piston). The respective outlet valve 50 is set up in such a way that it opens when the delivery pressure value present in the delivery chamber is sufficiently high, for example corresponds to the pressure value required on the output side of the liquid ring pump 1 .

In 6 another alternative embodiment of the impeller 4 is shown. The outlet opening 12 leads via the outlet valve 50 into an outlet chamber 54 which is arranged on the impeller body 28 and is specifically formed therein. For this purpose, the outlet chamber 54 has at least one chamber surface 56 inclined to the axis of rotation 6 . Due to the centrifugal force acting on the ring liquid 14, the ring liquid 14 that is also ejected is separated from the gas at this chamber surface 56, in that the ring liquid 14 is deposited on this chamber surface 56 and flows along it to the (front) side 32 of the impeller 4. In addition to the gas supply line, which is not shown in detail, there is also a liquid discharge line in the form of a pipeline (optionally integrated in the gas supply line) on this side 32, via which the ring liquid 14 separated from the gas is discharged during operation, fed to a cooling device and then returned to the pump chamber 3 becomes. In a variant that is not shown in detail, the chamber surface 56 runs parallel to the axis of rotation 6 and thus represents an inner surface of a circular cylinder.

In a further variant that is not shown in detail, means for supporting the gas-liquid separation are additionally arranged in the outlet chamber 54 . These are guide vanes that support the centrifugal force-related separation of the ring liquid 14 .

On the other side 34 of the impeller 4 is in 6 illustrated embodiment, the inflow opening 36 is also formed in the bottom wall 24 of the pumping chamber 8. In the inflow opening 36 there is also a non-return valve (hereinafter referred to as inflow valve 58) which prevents the gas from flowing back and thus also deflagrating from the delivery chamber 8 in the suction area 20 prevents. The use of the inflow valve 58 and the outlet valve 50 enables particularly precise control of the loading and unloading of the pumping chamber 8 with the gas to be pumped. In addition, the development of noise as a result of dynamic pressure relief in or out of the respective delivery chamber and any associated foaming between the gas and the ring liquid 14 are effectively prevented. In this exemplary embodiment, the inflow valves 58 and the outlet valves 50 are each designed as membrane valves. Due to the arrangement in the bottom wall 24 described above, the sealing or closing effect of the outlet valves 50 is supported by the centrifugal force. Correspondingly, in this arrangement, the opening of the inflow valves 58 is also assisted by the centrifugal force.

In 7 another exemplary embodiment of the impeller 4 is shown. The line of intersection of this schematic sectional view runs in particular approximately vertically. As an additional means (as an alternative to the guide vanes mentioned above) to support the gas-liquid separation, a guide disk 60 is arranged in the (common) outlet chamber 54, which supports the centrifugal force-induced separation of the annular liquid 14. Specifically, the guide disk 60 is coupled to the pump base body 28 in a torque-proof manner. The outlet opening 12 (in particular the channel formed by it) and/or the outlet valve 50 are aligned in such a way that the outflowing gas and the following annular liquid 14 impinge on the guide disk 60 rotating with the impeller 4 . Passage openings 62 for the gas are arranged radially on the inside in guide disk 60 (distributed over its circumference). Due to the centrifugal force caused by the rotation of the guide disk 60 , the annular liquid 14 runs off radially outwards on the guide disk 60 . The ring liquid 14 then runs off to the side 32 on the (conically widening and rotating) chamber surface 56 . Across a gap 64 , which is sufficiently small to prevent at least excessive inflow of the ring liquid 14 into the gap 64 , the ring liquid 14 flows onto the stationary region of the liquid ring pump 1 , specifically onto the pump housing 2 .

An annular channel 66 is formed in the pump housing 2 , which is designed as a kind of drainage channel for the annular liquid 14 , which runs off the chamber surface 56 onto the pump housing 2 . On an underside of the pump housing 2, an outlet is formed in the ring channel 66, which represents the liquid discharge described above. The drain is designed in such a way that the passage of gas is prevented. For example, the outlet is designed like a siphon or has such a small diameter that there is always a residual liquid level of the ring liquid 14 at the outlet and thus closes it against the passage of gas.

The subject of the invention is not limited to the embodiments described above, but is only defined in the claims. Rather, further embodiments can be derived from the above description by a person skilled in the art. In particular, the individual features described with reference to the various exemplary embodiments and their design variants (for example the arrangement and design of the outlet and inflow valves 50 and 58 and the side walls 26) can also be combined with one another in other ways.

Reference List

1

liquid ring pump

2

pump housing

3

pump chamber

4

impeller

6

axis of rotation

8th

conveyor chamber

10

partition

12

exit port

14

ring liquid

16

direction of rotation

18

liquid ring

20

suction area

22

print area

24

bottom wall

26

Side wall

28

pump body

30

plane of symmetry

32

side

34

side

36

inflow opening

40

control ring

42

annular gap

50

exit valve

54

exit chamber

56

chamber area

58

inflow valve

60

idler disk

62

passage opening

64

gap

66

ring canal

Claims (11)

1. Liquid ring pump (1), having a pump housing (2) which surrounds a pump chamber (3) into which a pump liquid (14) is filled in the intended operating state, and having an pump wheel (4) which is arranged inside the pump chamber (3) and is rotatable about an axis of rotation (6) for conveying a gaseous working medium,

   - the pump wheel (4) having on its outer circumference a number of delivery chambers (8) separated from one another at least in the circumferential direction,

   - the pump wheel (4) having in each case an outlet opening (12), which is assigned to each delivery chamber (8) and is introduced locally into a bottom wall (24) of the pump wheel (4), which delimits the respective delivery chamber (8) radially on the inside, for the fluidic connection of the respective delivery chamber (8) to a pressure region (20) of the pump chamber (3),

   - wherein the bottom wall (24) runs along the axis of rotation (6) on both sides of the outlet opening (12) at least in sections inclined to the axis of rotation (6) in the direction of the outlet opening (12),

   - wherein the respective outlet opening (12) is arranged at a point of the respective conveying chamber (8) with the smallest radial distance to the axis of rotation (6),

   characterized in that
   the pump wheel (4) has for each delivery chamber (8) in each case an inflow opening (36) made locally in one of the walls bounding the delivery chamber (8) for fluidic connection of the respective delivery chamber (8) with a suction region (20) of the pump chamber (3).
2. Liquid ring pump (1) according to claim 1,
   wherein the pump wheel (4) is arranged eccentrically in the pump chamber (3) in such a way that a liquid ring (18) of the pump liquid (14) in the pressure region (20) of the pump chamber (3), which ring forms in the intended operation, completely covers at least one delivery chamber (8) in the radial direction.
3. Liquid ring pump (1) according to claim 1 or 2,
   wherein each delivery chamber (8) is formed symmetrically with respect to a radial plane of the pump wheel (4) forming a mirror surface (30), and wherein the outlet opening (12) is arranged in the mirror surface (30).
4. Liquid ring pump (1) according to one of claims 1 to 3,
   wherein the respective bottom wall (24) delimiting the delivery chamber (8) radially on the inside is substantially U-shaped or V-shaped along the axis of rotation (6).
5. Liquid ring pump (1) according to one of the preceding claims,
   wherein the inflow opening (36) is provided in the bottom wall (24) or a side wall (26) bounding the respective delivery chamber (8) on the end side.
6. Liquid ring pump (1) according to one of the preceding claims,
   wherein a check valve (50) is arranged within the outlet opening (12).
7. Liquid ring pump (1) according to any one of the preceding claims,
   wherein a check valve (58) is arranged within the inflow opening (36).
8. Liquid ring pump (1) according to one of the preceding claims,
   wherein the respective outlet opening (12) opens into an outlet chamber (54) arranged on the pump wheel (4), which is designed for centrifugal separation of the working medium from the pump liquid (14).
9. Liquid ring pump (1) according to claim 8,
   wherein means, in particular guide vanes or guide discs, are arranged in the outlet chamber (54) for assisting the separation of the working medium from the pump liquid (14).
10. Liquid ring pump (1) according to any one of claims 1 to 5,
    having a control ring (40) which is rotatable relative to the pump wheel (4) and closes the outlet openings (12) of the pump wheel (4) in sections on the outlet side against the pump wheel (4).
11. Liquid ring pump (1) according to any one of the preceding claims, wherein a poly-alpha-olefin is used as pump liquid (14).

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