WO2019045590A1

WO2019045590A1 - Pressure actuated seal arrangement

Info

Publication number: WO2019045590A1
Application number: PCT/RU2017/000636
Authority: WO
Inventors: Vitaly Vladimirovich Malinin; Kiran Kumar NARAIANAMURTKHI
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-08-31
Filing date: 2017-08-31
Publication date: 2019-03-07

Abstract

The present invention provides a pressure actuated seal arrangement (1) to regulate flow of a working medium flow from a high pressure area (2) to a low pressure area (3) through a gap (6) is presented. The pressure actuated seal arrangement (1) comprises a first part (4) and a second part (5), wherein the first part and the second part are located opposite to each other and arranged in such way that there is a gap (6) formed between the first part and the second part., The first part (4) and the second part (6) can be configured to be relatively rotatable parts, e.g. a rotor and a stator, or relatively stationary parts, e.g. various housing parts or cooling air plenums etc, within the rotating machine, e.g. within a gas turbine. The second part (5) comprises at least one flexible sealing arrangement (7) with at least one sealing element (8) extending in the gap (6). The at least one flexible sealing arrangement (7) is interposed between a high pressure area (2) and a low pressure area (3). According to the present invention at least one flexible sealing arrangement (7) further comprises a group of elastic elements (9). The group of elastic elements (9) is arranged in the high pressure area (2), and is adapted to move the at least one sealing element (8) depending on a pressure drop between the high pressure area (2) and the low pressure area (3) to regulate the extension of the gap (6).

Description

PRESSURE ACTUATED SEAL ARRANG ENT

The present invention relates to sealing arrangements employed to prevent a working medium to flow between two parts from a high pressure area to a low pressure area. In particular this invention relates to sealing in rotating machines, such as turbines (gas, steam, fluid), compressors, pumps, etc.

The control of the working medium (gas, steam, fluid) flow inside rotating machines is of paramount importance with regards to both functionality and effectiveness.

Seal arrangements are interposed between a high pressure area and a low pressure area to provide noncontact sealing. Different sealing techniques are used at various locations in the rotating machines to prevent leakage of the working medium both between two relatively rotating parts, e.g. a rotor and a stator, and two relatively stationary parts, e.g. various housing parts, cooling air plenums, etc.

Among the abovementioned seal arrangements labyrinth seals, mateface seals, strip seals, rope seals, finger seals could be distinguished.

The key issue in developing the seal arrangements is improving their sealing properties while maintaining the required life-span and reliability. One of the construction types satisfying these requirements are non-contacting finger seal arrangements.

The finger seal arrangements are known form prior art, f.e. US Patent N'6 811 154.

The finger seal arrangement operates due to the balancing of flexible sealing elements, often called a lift pads, on a 6

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thin film of the working medium that occurs on the surface of the opposite part to the one on which the finger seal arrangement is fixed to. In case of relatively rotating parts typically the finger seal arrangement is fixed on the stationary part. Therefore the flexible sealing element or the lift pad balances on a thin film of the working medium above the rotating part. The film thickness is very small, so leakage through the finger seal arrangement is to be 2-3 times lower than for a rigid labyrinth seal . The principle of such balancing is based on the arising of static and dynamic pressure of the working medium in a gap clearance under the lift pad. The appropriate choice and arrangement of all seal parameters, including the choice of initial gap clearance, allows ensuring the contactless operation of the seal with small gap clearance on different engine regimes .

The efficiency of the conventionally known finger seal arrangements could be improved by reducing the gap clearance. However, the gap clearance can only be reduced to a limited extent so as to avoid contact between the first part and the second part. In particular, such requirement should be satisfied for relatively rotating parts during the operation of the rotating machine since any contact of the first and the second part can result in damage to the parts of the rotating equipment.

The contact can be caused by many factors such as the eccentricity of a rotating part, centrifugal growth, vibrations, manufacturing tolerances, misalignment during assembling etc. Additionally to that if a rotating machine were to operate only under steady- state conditions, it would be a simple matter to establish the desired close gap clearance relationship to obtain the greatest possible efficiency without allowing frictional interference between the elements. However, in reality, all rotating machines must initially be brought from a standstill condition up to the steady-state speed, and then eventually decelerate to the standstill condition.

This transitional operation is not compatible with the ideal low gap clearance condition just described since the variation in rotor speed also causes a variation in the size. Further, as the rotating machine is brought up to speed from a standstill position, the temperature of the working medium passing there through may be increased proportionately, thereby exposing all parts of the rotating machine to variable temperature conditions. These conditions cause thermal growth of the structures, and if the structures have different thermal coefficients of expansion, which is generally true, then there is also the occurrence of relative thermal expansion between the elements.

In many applications of rotating machines, there is a requirement to operate at variable steady-state speeds, and to transit between those speeds as desired in the regular course of operation.

As mentioned hereinbefore, a primary concern is to maintain the minimum flow of the working medium between two parts, in most cases between the stator and the rotor of the rotating machine, i.e. to maintain the minimum gap clearance while preventing any mechanical interaction.

Accordingly, the object of the present invention is to provide another variant of the seal arrangement such that the flow of a working medium from a high pressure area to a low pressure area is regulated. Therefore, the efficiency of such seal arrangement is increased. The object of the present invention is achieved by a pressure actuated seal arrangement as defined in claim 1. Advantageous embodiments of the present invention are provided in dependent claims. Features of claim 1 can be combined with features of dependent claims, and features of dependent claims can be combined together.

In an aspect of the present invention, a pressure actuated seal arrangement to regulate flow of a working medium flow from a high pressure area to a low pressure area through a gap is presented.

The pressure actuated seal arrangement comprises a first part and a second part, wherein the first part and the second part are located opposite to each other and arranged in such way that there is a gap formed between the first part and the second part.

The first part and the second part can be configured to be relatively rotatable parts, e.g. a rotor and a stator, or relatively stationary parts, e.g. various housing parts or cooling air plenums etc, within the rotating machine, e.g. within a gas turbine.

The second part comprises at least one flexible sealing arrangement with at least one sealing element extending in the gap. The at least one flexible sealing arrangement is interposed between a high pressure area and a low pressure area. According to the present invention at least one flexible sealing arrangement further comprises a group of elastic elements .

The group of elastic elements is arranged in the high pressure area, and is adapted to move the at least one sealing element depending on a pressure drop between the high pressure area and the low pressure area to regulate the extension of the gap.

The present invention is based on the insight that the elastic elements of the group are arranged in the high pressure area and are deformed due to the existing pressure drop between the high pressure area and the low pressure area. The more the pressure drop the more the elastic elements of the group are affected by deformation, the more pressure is put on the sealing element, since the elastic elements of the group are in a contact with the sealing elements. Therefore the sealing element is moved towards the first part. So, the extension of the gap between the first part and the second part, in particularly a gap clearance between the sealing element and the first part, is decreased.

As soon as the pressure drop between the high pressure area and the low pressure area decreases, the elastic elements of the group return to their initial condition allowing the sealing element removed from the first part. Thereby the extension of the gap, in particularly the gap clearance between the sealing element and the first part, increases.

Such pressure drop influences the geometry of the elastic element due to the fact that the at least one flexible sealing arrangement is not hermetic and the pressure drop arises on the elastic element as well.

Thus, the present invention is proposed to provide a new pressure actuated seal arrangement to regulate flow of a working medium from a high pressure area to a low pressure area through the gap .

Further embodiments of the present invention are subject of the further sub-claims and of the following description, referring to the drawings . In a possible embodiment of the pressure actuated seal arrangement at least one elastic element of the group is adapted to move the at least one sealing element in a first direction that is towards the first part in case the pressure drop is more that a given threshold, and to allow moving the at least one sealing element in an opposite direction to the first direction in case the pressure drop is less than a further given threshold. Therefore the pressure actuated seal arrangement can be configured to regulate the extension of the gap depending on the given threshold and the further given threshold. It can be required to provide different gap clearance for different operational modes of the rotating machine. In other possible embodiment of the pressure actuated seal arrangement the bottom end of the at least one elastic element of the group is attached to the at least one sealing element, and the top end of the at least one elastic element of the group is rigidly fixed to the second part. Due to the facts that the top end is rigidly fixed to the second part, while the bottom end is just attached to the at least one sealing element, and that the elastic element is of material allowing it to be elongated under the pressure of the working medium flow, all forcing of the elastic element deformation are directed to the bottom end while the elastic element is being deformed under the pressure drop between the high pressure area and the low. Therefore the bottom end is pressing on the at least one sealing element extending in the gap moving it closer to the first part. As a result the extension of gap, in particularly the gap clearance between the sealing element and the first part, decreases.

And vise versa, as soon as the pressure drop between the high pressure area and the low pressure area decreases, the elastic element recovers its initial shape. The bottom end of the elastic element return to its initial place. The at least one sealing element does not feel pressure from the bottom end side. It allows the at least one sealing element moving back to the second part. Therefore the gap clearance between the sealing element and the first part increases.

Such feature provides more sensitivity of the pressure actuated seal arrangement to the pressure drop .

In enhanced embodiment of the pressure actuated seal arrangement, the bottom end is bedded in to a groove of the at least one sealing element. This feature allows providing more pressure to the at least one sealing element and to fix the bottom end on the at least one sealing element, to avoid dismounting of the elastic element off the at least one sealing element.

In enhanced embodiment of the pressure actuated seal arrangement in a state when the pressure drop is more that the given threshold, at least two neighboring elastic elements are overlapped with each other. This feature allows using different shapes of the elastic elements.

In fact in a state when the pressure drop is less than the further given threshold, when the elastic elements are in their initial shape, there can be spaces between two neighboring elastic elements. However as soon as the pressure drop growths the elastic elements starts deforming and may overlap each other. Such overlapping can be caused by shapes of the elastic elements and mutual placement of the neighboring elastic elements.

It should be taken into account that the less space between two neighboring elastic elements the better. In an ideal case there are no spaces between neighboring elastic elements of the group. In this case the elastic elements became more sensible to the pressure drop and the regulation of the gap between two parts became more precise.

On the other hand in some case such overlapping is required due to the shape of the first part and the second part to prove full coverage of the surface along the first part and provide the same height of the gap clearance along the first part .

In other possible embodiment of the pressure actuated seal arrangement the group of the elastic elements comprises at least three neighboring elastic elements that are assembled in a staggered way. It means that one side face of the elastic element overlaps the neighboring elastic element by- covering it from above, while an opposite side face of the elastic element is overlapped with the neighboring elastic element by being covered from above by this neighboring elastic element.

It is especially demanded when the first part and the second part are of irregular shape, not straight surfaces. For example, the first part is a stator and the second part is a rotor. In this particular case it is preferable to have all elastic elements of the group assembled in a staggered way in circumference direction.

Such assembling of the elastic elements allows avoiding existence of spaces between the neighboring elastic elements.

In addition to that such assembling allows providing the same height of the gap clearance along the first part of complex contours .

In other possible embodiment of the pressure actuated seal arrangement the at least one elastic element of the group is of a zigzag or wavy shape.

Possibility of selecting among different shapes of the elastic elements allows providing required regulation of the extension of the gap between the first part and the second part, in particularly the gap clearance between the sealing element and the first part, and allows providing required size of the gap clearance for different regimes of the rotating machine.

In other possible embodiment of the pressure actuated seal arrangement each elastic element of the group has a seal that is attached to the respective elastic element and arranged in such way that there is no spacing between the respective elastic element and the neighboring elastic element.

Absence of spacing between the respective elastic element and the neighboring elastic element allows providing more precise regulation of the gap clearance between the sealing element and the first part, since the group of elastic elements become more sensitive to the pressure drop and all pressure from the working medium flow participates in deforming the elastic elements of the group. In addition to that such assembly allows minimizing uncontrolled leakage of the working medium through the flexible sealing arrangement that is not hermetic.

In enhanced embodiment of the pressure actuated seal arrangement the seal is attached to at least two neighboring elastic elements. Such the seal attached to both neighboring elastic elements prevents the leaking of the working medium through the spacing between the respective neighboring elastic elements.

In other possible embodiment of the pressure actuated seal arrangement the at least one elastic element of the group is a bellows or sylphon. The bellows has its internal pressure that can be changed. This feature allows customizing the pressure actuated seal arrangement to the required conditions and to the particular rotating machine.

In enhanced embodiment the pressure actuated seal arrangement further comprises a control unit that is adapted to provide a predefined pressure within the at least one elastic element, that is the bellows. In other words the control unit allows controlling and changing the predefined pressure within the bellows . The pressure inside the elastic element also exerts impact on the force of pushing of the elastic element on the sealing element. The control unit can provide the pressure inside the elastic element that is less than the pressure in the low pressure area. The control unit can do it both in manual and automatic regimes.

Therefore such feature allows actively regulating the gap clearance between the sealing element and the first part with high accuracy during the operation of the rotating machine.

In other possible embodiment of the pressure actuated seal arrangement the at least one flexible sealing arrangement further comprises at least one temperature element. The at least one temperature element is adapted to prevent movement of the at least one sealing element by the at least one elastic element of the group till the temperature of the working medium is more that a given temperature threshold. It can be required for some operational modes of the rotating machines: when the pressure drop is already high, but the rotating machine is still in starting mode, and therefore the gap clearance between the first part and the sealing element is still needed to be large enough. The temperature element prevents the elastic element pressing the sealing element, and therefore prevents moving the sealing element towards the first part.

In fact the vise versa situation is possible as well, when the temperature element prevents the sealing element returning to its initial position.

In enhanced embodiment of the pressure actuated seal arrangement the temperature element is a bimetallic element. The bimetallic elements are well known. The bimetallic element bends one way if heated, therefore can be used as a temperature catch for the elastic element and / or for the sealing element.

In other possible embodiment of the pressure actuated seal arrangement at least one of the first part and the second part is a rotating part and another part is a stationary part. Therefore the first direction is a radial direction towards the first part. And therefore the at least one elastic element of the group is adapted to move the at least sealing element radially toward the first part in case the rotation frequency of the rotating part is more that a given rotating threshold. to allow moving the at least one sealing element radially outward of the first part in case the rotation frequency of the rotating part is less than the further given rotating threshold This feature allows using the pressure actuated seal arrangement to regulate the flow of a working medium from the high pressure area to the low pressure area through the gap between two relatively rotating parts, f.e. between the rotor and the stator in a turbine stage.

For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in accompanying drawings. The invention is explained in more details below using exemplary embodiments which are specified in the schematic figures of the drawings, in which:

FIG. 1 schematically illustrates a pressure actuated seal arrangement in accordance with the present invention;

FIG. 2 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG. 3 schematically illustrates a finger seal arrangement (prior art) ;

FIG. 4 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG. 5 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention; FIG. 6 schematically illustrates an example of the elastic element in accordance with the present invention;

FIG. 7 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention; FIG. 8 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG. 9 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG. 10 schematically illustrates an example of the elastic element in accordance with the present invention;

FIG. 11 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG. 12 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention; FIG. 13 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG 14 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG 15 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG 16 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention;

FIG 17 schematically illustrates an embodiment of the pressure actuated seal arrangement in accordance with the present invention; Various embodiments are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be noted that the illustrated embodiments are intended to explain, and not to limit the invention. It may be evident that such embodiments may be practiced without these specific details. It may be noted that in the present disclosure, the terms "first", "second", etc. Are used herein only to facilitate discussion, and carry no particular temporal or chronological significance unless otherwise is indicated.

FIG 1 illustrates a pressure actuated seal arrangement 1 to regulate flow of a working medium (gas, steam, fluid) from a high pressure area 2 to a low pressure area 3 in accordance with the present invention.

It is possible both to increase the flow of the working medium from the high pressure area 2 to the low pressure area 3 and to minimize it by the means of the pressure actuated seal arrangement 1.

The pressure actuated seal arrangement 1 comprises a first part 4 and a second part 5, wherein the first part 4 and the second part 5 are located opposite to each other, so the surface 12 of the first part 5 is opposite to the surface 13 of the second part 5. The first part 4 and the second part 5 are arranged in such way that there is a gap 6 of the height H between them.

The first part 4 and the second part 5 can be configured to be relatively rotating parts or relatively stationary parts within the rotating machines, such as turbines (gas, steam, etc.), compressors, pumps, etc.

In case of relatively rotating parts, the first part 4 may be, but not limited to, a rotor segment of a turbine, whereas the second part 5 may be, but not limited to, a stator segment of the turbine. /And vise versa, the first part 4 can be configured to be stationary within the rotating equipment and the second part 5 is configured to be rotatable within the rotating equipment, e.g. the first part 4 may be, but not limited to, a stator segment of a turbine, whereas the second part 5 may be, but not limited to, a rotor segment of the turbine .

In case of relatively stationary parts, the first part 4 and the second part 5 can be, e.g. various housing parts, cooling air plenums etc.

According to the present invention the second part 5 comprises at least one flexible sealing arrangement 7, with at least one sealing element 8 extending in the gap 6.

In fact in the enhanced embodiment of the pressure actuated seal arrangement 1 each of the first part 4 and the second part 5 may have the at least one flexible sealing arrangement 7 with the at least one sealing element 8 extending in the gap 6 as shown on FIG 2.

The pressure actuated seal arrangement 1 can include one flexible sealing arrangement 7 or a plurality of the flexible sealing arrangements 7 that are distributed along the second part 5 in the streamwise direction 11 and / or a direction that is perpendicular to a streamwise direction 11. Alternatively the plurality of the flexible sealing arrangement 7 may be distributed along both the first part 4 and the second part 5. W

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The sealing element 8 extends in the gap 6 towards the first part 4. The sealing element 8 can be either angled or slanted or parallel to the surface 12 of the first part 4.

The sealing element 8 can be of different configuration and shape. The sealing element 8 should be configured to be able to move and / or bend in the direction from the second part 5 to the first part 4 and backwards.

The flexible sealing arrangement 7 can comprise one sealing element 8 or a plurality of the sealing elements 8. The flexible sealing arrangement 7 with the at least one sealing element 8 extending in the gap 6 forms a barrier against the flow of the working medium between the first part 4 and the second part 5.

The flexible sealing arrangement 7 is configured to be able to change its longitude size. It can be implemented in different ways, for example by bending the sealing element 8 from the parallel state (when the sealing element 8, e.g. the lift pad, is parallel to the surface 12 of the first side 4) to the state when the sealing element 8 is angled or slanted with respect to the surface 12 of the first side 4. Other approach is to have the sealing element fixed on a holding element 27 that allows moving the sealing element 8 in the direction from the second part 5 to the first part 4 and backwards . The holding element 27, that is the element of the flexible sealing arrangement 7, can be, for example, a spring element or a bellows element. The holding element should fix the sealing element 8 allowing it to move only in the direction from the second part 5 to the first part 4 and backwards and without allowing the sealing element 8 to move in other directions . However the flexible sealing arrangement 7 is fixed to the second part 5 and not movable relatively to the second part 5.

The flexible sealing arrangement 7 with the sealing element 8 is not hermetic. So there can be some uncontrolled leakages of the working medium through the flexible sealing arrangement 7 with the sealing element 8. Such uncontrolled leakages of the working medium can be connected with a structure of the flexible sealing arrangement 7. The flexible sealing arrangement 7 can be a finger sealing arrangement (known from prior art) with lift pads extending in the gap 6 towards the first part 4 and oriented along the surface 12 of the first part 4. FIG 3 illustrates the finger sealing arrangement known from prior art. The finger sealing arrangement 7 comprises a front pate 100, an upstream plate with padless fingers 101, a downstream plate with padded fingers 102, and a back plate 103.

The finger sealing arrangement 7 interpose between the high pressure area 2 and the low pressure area 3 between the first part 4 and the second part 5 (not shown on FIG 3) . The downstream plate 102 has special lift pads 8 extended only to the low pressure area 3. The downstream plate 102 with padded fingers represents the holding element 27 with the sealing element 8. The working medium flows in the direction 11 from the high pressure area 2 to the low pressure area 3, meet a barrier in the form of the finger sealing arrangement 7 and leaks through the gap clearance 10 between the sealing element 8 and the surface 12 of the first part 4.

The structure of the flexible sealing arrangement 7 is out of the present invention framework. The flexible sealing arrangements 7 are know in prior art, for example from US Patent 6 811 154. According to the present invention the flexible sealing arrangement 7 comprises a group of elastic elements 9 (on FIG 1 only one elastic element is shown) . The group of elastic elements 9 can comprise one elastic element 9 or a plurality of the elastic elements 9.

Each elastic element 9 of the group has the ability of the longitudinal deformation. In other words, the elastic element 9 is capable to change its length 1. The length 1 of the elastic element 9 in terms of the present disclosure refers to the size 1 of the elastic element 9 in direction between the second part 5 and the first part 4, in other word from the top end 14 of the elastic element 9 to the bottom end 15 of the elastic element 9 as it is shown on FIG 3. Such elasticity of the elastic element 9 can be achieved both by shape of the elastic element 9 and material the elastic element 9 is made of .

In addition to that the elastic element 9 is able to return to its original size and shape when that influence or force causing its deformation is removed. There a lot of known materials, for example such as stainless steel, plastics, nickel based alloys, etc. that can be used for the elastic element 9.

Additionally the elasticity of the elastic element 9 can be achieved by the shape of the elastic element. For example the elastic element 9 can be of zigzag shape as shown on FIG 4 or of wavy shape as shown on FIG 6 or of spherical shape as shown on FIG 1.

In case of relatively rotating parts 4, 5, the flexible sealing arrangement 7 can be a ring shaped arrangement. And the zigzags or waves in the shape of the elastic element 9 are executed in circumference direction. In case of relatively stationary parts 4, 5, the zigzags or waves in the shape of the elastic element 9 are executed perpendicularly to the streamwise direction in the direction from the second part 5 to the first part 4. Also the elastic element 9 of the group can be a bellows as shown on FIG 6.

The shape and the material of the elastic elements 9 of the group should be selected by experts based on required working conditions of the rotating machine. The at least one flexible sealing arrangement 7 with the at least one sealing element 8 narrows the gap 6 between the first part 4 and the second part 5 leaving the gap clearance 10. The gap clearance 10 of height h is formed by the at least one sealing element 8, in particularly a surface 11 of the at least one sealing element 8 and the first part 4. By regulating the height h of the gap clearance 8 the regulation of the flow of a working medium from a high pressure area 2 to a low pressure area 2 through the gap 6 is achieved.

The group of elastic elements 9 is arranged in the high pressure area 2, and is adapted to move the at least one sealing element 8 depending on a pressure drop between the high pressure area 2 and the low pressure area 3 to regulate the extension of the gap 6 that is open for the working medium flow, in other words, the height h of the gap clearance 10.

The pressure actuated seal arrangement 1 works as follows.

The working medium flows in the direction 11 from the high pressure area 2 to the low pressure area 3 between the first part 4 and the second part 5. Such flow is nearly blocked by the flexible sealing arrangements 7 with the sealing element

8 and strongly compressed in the area of the sealing element 8. So there is the controlled flow of the working medium through the gap clearance 10 between the sealing element 8 and the first part 4 and the uncontrolled leakages of the working medium through the flexible sealing arrangement 7 due to the fact it is not hermetic.

According to the present invention the flexible sealing arrangement 7 comprises the group of the elastic elements 9 that is arranged in the high pressure area 2. Due to the ability of the elastic elements 9 to change its length (to the longitudinal deformation) , the length 1 of the elastic elements 9 is being changed while the pressure drop between the high pressure area 2 and the low pressure area 3 is changing .

The elastic element 9 has two sides 21, 22. A front side 21 of the elastic element 9 is turned to the flow of the working medium running in the direction 11. A back side 22 is an opposite of the front side 21. Due to the fact that the flexible sealing arrangement 7 is not hermetic, the pressure drop also appears on the elastic element 9. So, on the front side 21 of the elastic element 9 there is a high pressure area, but on the back side 22 of the elastic element 9 there is a low pressure area.

Therefore in case the pressure drop between the high pressure area 2 and the low pressure area 3 increases, the elastic element 9 while deforming presses on the sealing element 8 and moves the sealing element 8 in a first direction that is towards the first part 4 therefore the length of the flexible sealing arrangement 7 increases as well. As a result of it the height h of the gap clearance 10 decreases. Consequently the flow of the working medium through the gap 6 decreases. It is possible to select the elastic elements 9 with such characteristic that the flow of the working medium through the gap 6 is minimized, but still there is no direct contact between the sealing element 8 and the surface 12 of the first part 4.

And vise versa in case the pressure drop between the high pressure area 2 and the low pressure area 3 decreases, the elastic element 9 returns to its initial shape and length, therefore it allows moving the sealing element 8 in an opposite direction to the first direction, in other words towards the second part 5. As a result of it the height h of the gap clearance 10 increases. Consequently the flow of the working medium through the gap 6 increases as well.

Taking into account mentioned above it is possible to regulate the flow of the working medium through the gap 6 by means of the pressure actuated sealing arrangement 1.

In case the flexible sealing arrangement 7 would have been a hermetic arrangement, the pressure on the front side 21 of elastic element 9 and the pressure on the back side 22 of the elastic element would be the same and the present pressure actuated seal arrangement 1 would not work.

The shape and characteristics of the elastic element 9 should be defined by experts in such way to provide required sensitivity of the pressure actuated seal arrangement 1 to the working conditions of the rotating machine.

Additionally, it is possible to select the elastic element 9 in such way that the elastic element moves the at least one sealing element 8 in towards the first part 4 only in case the pressure drop is more that a given threshold.

Also it is possible to select the elastic element 9 in such way that the elastic element 8 returns to its initial length in case the pressure drop is less than a further given threshold. The given threshold and the further given threshold should be defined by experts based on requirements of the particular rotating machine.

The further given threshold is less than the given threshold. In order to provide more sensitive interaction between the elastic element 9 and the seal element 8 and transfer more pressure from the elastic element 9 to the seal element 8 it is recommended to fix rigidly the top end 14 of the elastic element 9 to the second part 5. The top end 14 can be fixed directly to the second part 5 or to the flexible sealing arrangements 7, but close to the second part 5. The key issue is that the top end 14 should remain unmovable in relation to the second part 5.

While the top end 14 of the elastic element 9 is rigidly fixed to the second part 5, the bottom end 15 of the elastic element 9 should be just attached to the sealing element 8. In other words, the bottom end 15 should be in contact with the sealing element 8 to be able to move it towards the first part 4 to narrow the gap clearance 10. The elastic element 9 has a section that is between the top end 14 and the bottom end 15, which is flexible and susceptible to the pressure drop.

Additionally there can be made a groove 16 in the sealing element 8 (shown on FIG 7) . And the bottom end 15 of the elastic element 9 can be bedded into this groove 16 to provide more solid interaction between the elastic element 9 and the sealing element 8 and to prevent dismount of the elastic element 9. Also it will increase sensitivity of the sealing element 8 to the pressing from the elastic element 9 side. The groove 16 should be located on the surface 17 of the seal element 8 that is opposite to the surface 13 of the second part 5. The location of the groove 16 on the surface 17 of the seal element 8 should be defined by experts since it can influence on the size of the movement of the seal element 8 and consequently to the height h of the gap clearance 10.

The two neighboring elements 9 can have a space between them, can contact each other partially or even can overlap with each other. For example in a state when the pressure drop is less than the further given threshold, the elastic elements 9 do not overlap with each other. But as soon as the pressure drop is more that the given threshold, at least two neighboring elastic elements 9, 9' , especially their bottom ends 15 can overlap with each other as it is shown on FIG 8. Such overlapping of the two neighboring elastic elements 9, 9' can be in the middle parts as it is shown on FIG 9. Such overlapping can appear in case the elastic elements 9, 9' of half sphere shape as it is shown on FIG 10.

It is preferable to assemble the elastic elements 9 of the group in such way that there are no spaces between the elastic elements 9 of the group. It will lead to more sensitivity of the pressure actuated seal arrangement 1 to the pressure drop and allow regulating the flow of the working medium with high accuracy. Also it will decrease the uncontrolled leakage of the working medium.

Such assembling can be done in different ways.

One way is to assemble the elastic elements in a staggered way as it is shown on the FIG 11. It means that one side face of each elastic element 9 overlaps the neighboring elastic element 9' by covering it from above, while another side face of the respective elastic element 9 is overlapped with the neighboring elastic element 9' ' by being covered it from above by this neighboring elastic element 9' ' .

In case of relatively rotating parts 4, 5 neighboring elastic elements 9, 9' , 9' ' are assembled in the staggered way in circumferential direction.

Other way of assembling of the group of elastic elements 9 is to have a seal 18 attached to each elastic element 9. Such seals 18 should be arranged in such way that there is no spacing between the respective elastic element 9 and neighboring elastic element 9' .

Such seal 18 can be attached to the respective elastic elements by different ways, for example, glued or fixed by other means. The seal 18 can be attached to the respective elastic element 9 both from the front side 21 of the elastic element 9 and from the back side 22 of the elastic element 9. The seal 18 covers the space between the respective elastic element 9 and the neighboring elastic element 9' .

Fig 12 illustrates the elastic element 9 with the seal 18 attached to the back side 22 of the elastic element (shown on FIG 12 (I) ) and two neighboring elastic elements 9, 9' with the seals 18 attached to the back side 22 of the elastic elements 9, 9' (shown on FIG 12 (II) ) .

In enhanced embodiment of the pressure actuated seal arrangement 1, the seal 18 is attached to at least two neighboring elastic elements 9, 9' and is adapted to avoid leaking of the working medium through the spacing between the respective neighboring elastic elements 9, 9' . In other words each two neighboring elastic elements 9, 9' have the seal 18 attached to both of them.

For example, sealing cloth, graphite pads, etc can be used as the seal 18. The material of the seal 18, its shape, and method of attaching to the elastic element 9 should be chosen by experts based on the temperature used in the rotating machine and other operational conditions .

In further embodiment the flexible sealing arrangement 7 comprises a temperature element 19 (shown on FIG 13) . The temperature element 19 is arranged in such way that it prevents movement of the at least one sealing element 8 in the first direction till the temperature of the working medium is more that a given temperature threshold. It can be accomplished in different ways. For example the temperature element 19 can keep the elastic element 9 from the pushing the sealing element 8 till the temperature of the working medium is more that the given temperature threshold. Or it can be adapted to prevent movement of the sealing element 8 independently on the pressure from the elastic element 9 side till the temperature of the working medium is more that the given temperature threshold. So, in fact the temperature element 19 works as a trigger. The temperature element 19 can be integrated into the flexible sealing arrangement 7. The given temperature threshold should be defined by experts.

The temperature element 19 can be mechanical, for example a bimetallic plate.

Such temperature element 19 can be accomplished as a bimetallic element that bends one way if heated. Therefore it can work as a temperature catch for the elastic element 9 and / or for the sealing element 8. While the temperature is less than the given temperature threshold the bimetallic element 19 is straight and prevent, for example, the elastic element 9 from putting pressure to the sealing element 8, and therefore prevents the sealing element 8 from moving towards the first part 4 and narrowing the gap clearance 10. As soon as the temperature of the working medium is more that the given temperature threshold, the bimetallic element 19 bends and releases the elastic element 9, therefore the elastic element 9 puts pressure to the sealing element 8 and moves it to the first part 4 narrowing the clearance gap 10.

Alternatively the temperature element 19 can be accomplished, for example, as a gas spring, bimetallic valve, etc.

In case the elastic element 9 is accomplished in form of a bellows, the elastic element 9 has its internal pressure in a bellows internal area 24. Therefore such elastic element 9 is adapted to move the at least one sealing element 8 depending on a pressure drop between the high pressure area 2 and the low pressure area 3 to regulate the extension of the gap 6. The internal pressure of the bellows 9 also influences on ability of the elastic element 9 to move the at least one sealing element 8.

An example of the embodiment of the pressure actuated seal arrangement 1 with the bellows as an elastic element 9 is shown on FIG 14. The bellows 9 rests on a bellows holder 25 that is the part of the flexible seal arrangement 7. The sealing element 8 takes stand on the bellows 9. The bellows holder 25 has a channel 23 inside it that connects the internal area 24 of the bellows 9 and the low pressure area 3. In such case the pressure actuated seal arrangement 1 works follows: as soon as the pressure drop between the high pressure area 2 and the low pressure area 3 growth, the pressure drop between high pressure area 2 and the bellows internal area 24 growth as well. As a result of it the bellows 9 is getting shorter and moving the sealing element 8 towards the first part 4. Therefore the height h of the gap clearance 10 decreases and the flow of the working medium between two parts 4, 5 decreases as well. And vise versa as soon as the pressure drop between the high pressure area 2 and the low pressure area 3 decreases, the pressure drop between high pressure area 2 and the bellows internal area 24 decreases as well. As a result of it the bellows 9 is getting extended and moving the sealing element 8 towards the second part 5. Therefore the height h of the gap clearance 10 increases and the flow of the working medium increases as well.

In fact the channel 23 can be equipped with the temperature element 19, such as bimetallic element. Therefore the internal pressure of the bellows 9 in the bellows internal area 24 can be regulated by such temperature element 19 depending on the temperature of the working medium. The location of the temperature element 19 regarding the channel 23 and the bellows 9 should be defined by experts. For example the temperature element 19 can close the orifice of the channel 23 that is located inside the bellows internal area 24 (not shown on FIG) or the opposite orifice of the channel 23 as it is shown on FIG 14. In enhanced embodiment of the pressure actuated seal arrangement 1 the flexible sealing arrangement and the temperature element 19 can be arranged in such way that the temperature element 19 prevents influence of high pressure on the bellows 9 depending on the temperature of the working medium. It can be done by equipping a channel 26 on the holding element 27 by the temperature element 19 as it is shown on FIG 15.

Alternatively the flexible sealing arrangement can be equipped with two temperature elements 19 as it is shown on FIG 15.

By choosing appropriate temperature elements 19 it is possible to regulate the height h of the gap clearance 10 and therefore to regulate the flow of working medium through the gap 6 depending on the temperature of the working medium.

In enhanced embodiment of the pressure actuated seal arrangement 1 it further comprises a control unit 20 that is adapted to provide a predefined pressure within the elastic element 9 that is a bellows. The control unit 20 can be managed in a manual regime or in automatic regime, or in combined way. The control unit 20 may be adapted to change the predefined pressure within the elastic element 9 during the time. Also the change of the predefined pressure within the elastic element 9 can be put into dependence from different internal parameters, such as temperature of the working medium, rotation frequency of a rotor, etc. and / or external parameters, such a time. The control unit 20 can receive signals form sensors established inside the rotating machine or outside of it.

Due to the ability of the control unit 20 to provide required predefined pressure within the elastic element 9, it is possible to regulate the height h of the gap clearance 10 and therefore to regulate the flow of working medium through the gap 6.

The work of the pressure actuated deal arrangement 1 with the control unit 20 and the bellows 9 as an elastic element is based on the fact that in case the pressure drop between the internal pressure of the bellows 9 and an outside pressure growth, the bellows 9 becomes shorter. And vise versa the less the pressure drop between the internal pressure of the bellows 9 and an outside pressure, the more elongated the bellows is .

In case the control unit 20 provides the predefined pressure within the elastic element 9 that is less than the high area pressure 2 the embodiment of the pressure actuated seal arrangement 1 can look as it is shown on FIG 16. The control unit 20 may provide the predefined pressure within the elastic element 9, for example, by a channel (not shown on FIG 16) arranged in the bellows holder 25 and connected with the bellows internal area 24.

In case the control unit 20 provides the predefined pressure within the elastic element 9 that is more than the high area pressure 2 the embodiment of the pressure actuated seal arrangement 1 may look as it is shown on FIG 17. The predefined pressure within the elastic element 9 may be provided, for example, through special orifices (not shown on FIG 17) in the second part 5.

In case relatively rotating parts 4, 5, the pressure of the elastic element 9 on the sealing element will depend on the rotation frequency of the rotating part 4, 5. The more rotation frequency of the rotating part 4, 5, the more elongated the elastic element 9 becomes, therefore the more pressure on the sealing element 8 the elastic element 9 provides. Therefore the sealing element is moved towards the first part 4 and the height h of the gap clearance 10 decreases. As a result the flow of the working medium through the gap 6 between the first part 4 and the second part 5 decreases and can be minimized.

And vise versa the less rotation frequency of the rotating part 4, 5, the shorter the elastic element 9 becomes, therefore the less pressure on the sealing element 8 the elastic element 9 provides. Therefore the sealing element moves towards the second part 5 and the height h of the gap clearance 10 increases. As a result the flow of the working medium through the gap 6 between the first part 4 and the second part 5 increases . While the present invention has been described in detail with the reference to certain embodiments, it should be appreciated that the present invention is not limited to those precise embodiments. Rather, in view of the present disclosure which describes exemplary modes for practicing the invention, many modifications and variations would present themselves to those skilled in the art without departing from the scope and spirit of this invention. The scope of the invention is, therefore, indicated by the following claims rather than by the foregoing description. All changes, modifications, and variations coming within the meaning and range of equivalency of the claims are to be considered within their scope.

Reference numerals

1 - pressure actuated seal arrangement

2 - high pressure area

3 - low pressure area

4 - first part

5 - second part

6 - gap

7 - flexible sealing arrangement

8 - sealing arrangement

9, 9' , 9' ' - elastic element

10 - gap clearance

11 - streamwise direction

12 - surface of the first part

13 - surface of the second part

14 - top end

15 - bottom end

16 - groove

17 - surface of the sealing element

18 - seal

19 - temperature element

20 - control unit

21 - front side

22 - back side

23, 26 - channel

24 - bellows internal area

25 - bellows holder

27 - holding element

100 - front plate

101 - upstream plate with padless fingers 102 - downstream plate with padded fingers

103 - back plate

Claims

PATENT CLAIMS

1. A pressure actuated seal arrangement (1) to regulate flow of a working medium from a high pressure area (2) to a low pressure area (3) through a gap (6) , comprising a first part (4) and a second part (5) , wherein the first part (4) and the second part (5) are arranged in such way that the gap (6) is formed between the first part (4) and the second part (5) , and wherein the second part (5) comprises at least one flexible sealing arrangement (7) with at least one sealing element (8) extending in the gap (6) , and a group of elastic elements (9) , wherein the group of elastic elements (9) is arranged in the high pressure area (2) , and is adapted to move the at least one sealing element (8) depending on a pressure drop between the high pressure area (2) and the low pressure area (3) to regulate the extension of the gap (6) .

2. The pressure actuated seal arrangement (1) according of claim 1, wherein at least one elastic element (9) of the group is adapted to move the at least one sealing element (8) in a first direction that is towards the first part (4) in case the pressure drop is more that a given threshold, and to allow moving the at least one sealing element (8) in an opposite direction to the first direction in case the pressure drop is less than a further given threshold.

3. The pressure actuated seal arrangement (1) according of any of claim 1 or 2 , wherein the at least one elastic element 9 comprises a bottom end (15) attached to the at least one sealing element (8) , and a top end (14) that is opposite to the bottom end (15) is rigidly fixed to the second part (5) .

4. The pressure actuated seal arrangement (1) according of claim 3, wherein the bottom end (15) is bedded in to a groove (16) of the at least one sealing element (8) .

5. The pressure actuated seal arrangement (1), according of any of claim 3 to 4 , wherein in a state when the pressure drop is more that the given threshold, at least two neighboring elastic elements (9, 9') overlap with each other.

6. The pressure actuated seal arrangement (1) according of any of claim from 1 to 4 , wherein the group comprises at least three neighboring elastic elements (9, 9', 9'') that are assembled in a staggered way.

7. The pressure actuated seal arrangement (1) according of any of claim from 1 to 5, wherein the at least one elastic element (9) of the group is of a zigzag or wavy shape.

8. The pressure actuated seal arrangement (1), according of any of claim from 1 to 7, wherein each elastic element (9) of the group has a seal (18) that is attached to the respective elastic element (9) and arranged in such way that there is no spacing between the respective elastic element (9) and a neighboring elastic element (9').

9. The pressure actuated seal arrangement (1), according of claim 8, wherein the seal is attached to at least two neighboring elastic elements and is adapted to avoid leaking of the working medium through the spacing between the respective neighboring elastic elements.

10. The pressure actuated seal arrangement (1) according of any of claim from 1 to 4 , wherein the at least one elastic element (9) of the group is a bellows.

11. The pressure actuated seal arrangement (1) according of claim 10, wherein the pressure actuated seal arrangement further comprises a control unit (20) that is adapted to provide a predefined pressure within the at least one elastic element (9) .

12. The pressure actuated seal arrangement (1) according of any of claim from 1 to 6 , wherein the at least one flexible sealing arrangement (7) further comprises at least one temperature element (19) that is adapted to prevent movement of the at least one sealing element (8) by the at least one elastic element (9) of the group till the temperature of the working medium is more that a given temperature threshold.

13. The pressure actuated seal arrangement (1) according of claim 12, wherein the at least one temperature element (19) is a bimetallic element.

14. The pressure actuated seal arrangement (1) according of any of claim from 1 to 13, wherein at least one of the first part (4) and the second part (5) is a rotating part and another part is a stationary part and therefore the first direction is a radial direction towards the first part, and therefore the at least one elastic element (9) of the group is adapted to move the at least sealing element (8) radially toward the first part (4) in case the rotation frequency of the rotating part (4, 5) is more that a given rotating threshold. to allow moving the at least one sealing element (8) radially outward of the first part (4) in case the rotation frequency of the rotating part (4, 5) is less than a further rotating given threshold.