Patent ID: 12241554

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

FIG.1shows a combination valve1with a quick-closing valve2and a regulating valve3in the closed state. The quick-closing valve2and the regulating valve3are arranged coaxially along a longitudinal axis3a.The combination valve1comprises a housing base body4with a sleeve60and a housing cover5. The sleeve60is inserted in the housing cover5and axially supported thereon. The housing base body4and the housing cover5are connected to each other with a screw connection6. The screw connection6, moreover, connects a valve attachment7and the housing cover5to the housing base body4. A regulating valve drive8is screwed to the valve attachment7. Alternatively, the valve attachment7can also be connected to the regulating valve drive8via a pin connection, welded to it or connected with a form-fitting connection.

The regulating valve3is embodied as a pressure-relieved tubular regulating valve and comprises a tubular valve body64, a stem shaft10and the regulating valve drive8. The regulating valve drive8is connected to the stem shaft10by a stem coupling11. The tubular valve body64comprises a labyrinth seal12and sealing rings13on its outside. The tubular valve body64also comprises an inner wall14which has a centric stem shaft bore15and pressure relief bores16arranged circularly around the former. The number of pressure relief bores16is designed in such a way that they provide a sufficient pressure flow area so that the regulating valve3only has to counteract a minimum pressure difference when closing. Preferably, four, six or eight pressure relief bores16are used. A larger or smaller number of pressure relief bores16is possible depending on the diameter of the pressure relief bores16.

The stem shaft10is guided through the stem shaft bore15and welded to the inner wall14. The stem shaft10is guided by the stem seal17. The stem seal17is arranged in the housing cover5and is axially fixed along the longitudinal axis3aby a tensioner18.

The inner diameter of the sleeve60is larger than the outer diameter of the stem shaft10. An annular interstice, in particular a gap area, is formed between the stem shaft10and the sleeve60so that an equalization of pressure is possible via this.

The quick-closing valve2comprises a quick-closing valve body19, a first cylindrical compression spring20, a second cylindrical compression spring21, a spring sleeve21awith an axial groove63, a bushing24and a tensioner22. The bushing24is connected to the quick-closing valve body19in a form-fitting manner and serves as a guide on the stem shaft10of the regulating valve3.

The tensioner22is screwed with self-blocking fine thread in the quick-closing valve body19according to a longitudinal dimension to be adjusted, whereby the tensioner22rests against the edge of the quick-closing valve body19and has a play of, for example, 0.2 mm towards the bushing24. The tensioner22has a hexagon head and can additionally be secured with a pin. Moreover, the tensioner22is also equipped with sealing rings23, which seal the internal space59against the spring chamber32in both directions via the movable stem shaft10.

The quick-closing valve2comprises a main steam channel25, a control valve26, a control line27, a chamber28, a shut-off line29and a shut-off valve30. The shut-off valve30is connected via a bore31to a spring chamber32. The spring chamber32is connected to the chamber28via eight bores33. The number of bores33is not limited to eight. The number and diameter of the bores33should be selected during the design such that the total area of all bores33corresponds to the area of the main steam channel25.

The annular interstice between the stem shaft10and the sleeve60is connected to the chamber28via at least one, in particular several, radial bores60a.Via the annular interstice and the radial bores60a,steam pressure from the spring chamber can decrease, as soon as, upon the opening of the quick-closing valve2, the tensioner22reaches the damping zone.

The steam chamber34is connected to the control valve26via the main steam channel25. When the control valve26is deactivated, the main steam channel25is connected to the control line27. The control line27ends in the chamber28, which is connected to the spring chamber32via the bores33. Consequently, when the control valve26is deactivated, the main steam can enter the spring chamber32through the main steam channel25, the control line27, the chamber28and the bores33and keep the quick-closing valve in the “closed” position.

The control valve26comprises a control drive35and a 3/2 way valve36, which comprises a valve body37which is embodied in particular as a valve cone. Furthermore, the control valve26comprises a channel38which is connected to the leakage steam line40by means of a shut-off valve39. Starting out from the activation state of the control valve26, the control line27is fluidly connected to the main steam channel25or the channel38.

The combination valve1comprises a guide sleeve41connected to the housing cover5, wherein the guide sleeve41is connected to the housing cover by a pin connection42. The guide sleeve41serves for guiding the quick-closing valve body19. Sealing rings43are arranged between the guide sleeve41and the quick-closing valve body19, which seal the steam chamber34against the spring chamber32.

The combination valve1comprises a steam strainer44with a steam strainer deflection45. The steam strainer44is connected to the housing cover5via a pin connection46. Furthermore, the steam strainer44rests in a recess47in the housing base body4.

Moreover, a diffuser49is arranged in the housing base body4at a steam exhaust port48. The diffuser49is connected to the housing base body4via a holding pin50.

The diffuser49has a first sealing area51and a second sealing area52. The first sealing area51serves as a valve seat for the quick-closing valve. The second sealing area52serves as a valve seat for the regulating valve3. Moreover, the diffuser49has a swirl-breaking device53. The swirl-breaking device53here has six swirl-breaking teeth54which are evenly distributed over the circumference of the diffuser49.

Hereinafter, the function of the combination valve1is explained with reference to various switching states.

InFIG.1the steam enters the combination valve1through a steam entry port55. The steam is then present at a control edge56of the quick-closing valve2. In addition, the steam guided through the main steam channel25, the control line27, the chamber28and the bore33is present at the back side of the quick-closing valve body19. Since the back side of the quick-closing valve body19has a larger control area than the control edge56, the quick-closing valve2remains closed due to the resulting force difference.

The regulating valve3is in the closed state. The steam is prevented from entering the steam exhaust port48by the first sealing area51and the second sealing area52.

FIG.2shows the combination valve1with the regulating valve3closed and the quick-closing valve2open. For this, the valve body37of the control valve26travels from a first end position57to a second end position58. The valve body37thus seals the main steam channel25and releases the channel38, which for the time being, however, is still closed towards the leakage steam line40by the shut-off valve39. The shut-off valve39is slowly opened via a ramp and the steam from the spring chamber32can escape through the bores33, the chamber28, the control line27, the 3/2 way valve36and the channel38via the leakage steam line40.

The quick-closing valve2is slightly lifted by the steam pressure present at the control edge56of the quick-closing valve2and, as soon as the complete front side of the quick-closing valve body19is exposed to pressure, it travels backwards into the spring chamber32and is opened. The quick-closing valve2travels backwards until the spring sleeve21a,supported by the spring force of the cylindrical compression spring21, covers the bores33and thus interrupts the steam flow to the leakage steam line40.

The quick-closing valve2has now reached the damping zone, and the pressure trapped in the spring chamber32then only slowly decreases via the gap until the tensioner22rests with its contact diameter Dkon the sleeve60and seals the spring chamber32. The opening process of the quick-closing valve is now complete and is confirmed by pressure measurements PT61in the control line27and PT62in the spring chamber32, both of which indicate ambient pressure.

The regulating valve3further preventing main steam from entering the steam exhaust port48via the second sealing area52. Depending on the embodiment of the regulating valve3and the diffuser49, the regulating valve3seals completely via the second sealing area52or allows a certain leakage steam flow.

FIG.3shows the combination valve with the quick-closing valve2open and the regulating valve3open. Here, the main steam is directed from the steam entry port55through the steam strainer44. The steam strainer deflection45of the steam strainer44deflects the steam flow by an angle α=45° in the direction of the steam exhaust port48.

The steam strainer deflection45minimizes the flow losses of the steam flow, which occur when the deflection is too strong. The steam flow flows via the steam chamber34in the direction of the steam exhaust port48. The swirl-breaking teeth54of the swirl-breaking device53in the diffuser49prevent turbulences of the steam flow and thus additionally reduce the flow losses of the steam. Moreover, the additional guidance of the regulating valve3in the swirl-breaking device53reduces the vibrations that occur.

The combination valve1according toFIG.3with opened quick-closing valve2and opened regulating valve3must completely shut off the steam supply within a very short time, in particular approx. 0.3 s, in order to protect or shut down the turbine. For this purpose, the control drive35is deactivated by means of a quick-closing command and the valve body37travels from its second end position58to the first end position57, as shown inFIG.1. As a result, the valve body37seals the channel38and releases the main steam channel25so that the steam enters the control line27and the chamber28via the 3/2 way valve36until it reaches the bores33.

Since the spring chamber32is first pressure less, the steam force present in the bores33shifts the spring sleeve21ain the closing direction against the considerably smaller spring force of the cylindrical compression spring21, thereby opening the inflow into the spring chamber32. At the same time, the entire back side of the quick-closing valve body19is exposed to pressure up to the contact diameter of the tensioner22on the sleeve60.

The steam impulse force and steam pressure force acting on the back side of the quick-closing valve body19, together with the mechanical closing force of the cylindrical compression spring20, cause the tensioner22to lift off the sleeve60, as a result of which the steam pressures on the front side and the back side of the quick-closing valve body19are now equalized, so that the quick closing operation on the quick-closing valve2is effected by shifting along the longitudinal axis3a.The quick-closing valve2has now returned to its initial position as shown inFIG.1, seals via the sealing area51on the diffuser49and shuts off the further steam inflow to the turbine. The closing operation is complete and is confirmed by the two pressure measurements PT61and PT62, both of which indicate the steam pressure in the steam entry port55.

The regulating valve3, as a redundant version as to the quick-closing valve2, also receives the quick-closing command, and the drive8, via the stem coupling11and the stem shaft10, shifts the regulating valve3along the longitudinal axis3auntil it is closed and seals the diffuser49via the sealing area52so that any steam inflow to the turbine is safely prevented. Since both valves, the quick-closing valve2and the regulating valve3, are now closed, the initial position according toFIG.1is reached.

FIG.4shows the combination valve1with the regulating valve3and quick-closing valve2open in the partial stroke test. For the partial stroke test, the shut-off valve30is slowly opened via a ramp during ongoing operation, i.e. with the regulating valve3open. Starting from the position shown inFIG.3, the main steam and the main steam pressure can now reach the spring chamber32via the main steam channel25, the shut-off line29, the shut-off valve30and the bore31and further via the axial groove63of the spring sleeve21ato the contact diameter Dkof the tensioner22, which rests on the sleeve60, with the result that the opened quick-closing valve2, due to the main steam pressure acting on the back side, altogether has a force component in the closing direction. Together with the spring forces of the mechanical closing components20and21acting in the closing direction of the quick-closing valve, the quick-closing valve2overcomes the steam pressure forces acting on the complete front side of the quick-closing valve body19and can thus leave its position towards the closing direction. The mechanical closing component20is designed not only to overcome the steam pressure force difference between the front side and the back side of the quick-closing valve body19, but also to have a sufficient closing force of approximately three times the mass of the quick-closing valve body19.

The steam present up to the contact diameter Dkof the tensioner22, supported by the closing force of the mechanical closing components20and21, thus displaces the quick-closing valve2in the longitudinal axis3ain the direction of the closed position thereof. This lifts the tensioner22off the sleeve60. The spring sleeve21a,supported by the spring force of the cylindrical compression spring21, first continues to seal the bores33, and via the axial groove63the tensioner22is now also completely exposed to pressure.

After a defined and adjustable stroke, the tensioner22strikes against the spring sleeve21aand shifts it coaxially to the longitudinal axis3a.This means that the bores33are no longer covered by the spring sleeve21a,so that the steam can escape through the bores33, the chamber28, the control line27, the 3/2 way valve36and the channel38into the leakage steam line40. This creates a balance of forces and a static pressure in the spring chamber32, which displaces the quick-closing valve into the partial stroke test position of about 15% to 20% of the full stroke and holds it there.

The successful partial stroke test is checked and confirmed via the two pressure transmitters PT61and PT62arranged upstream and downstream of the throttle point, respectively, by the pressure displayed in each case levelling off at a common mean pressure somewhere between the steam pressure in the steam entry port55and the ambient pressure. Then, the shut-off valve30is closed again. The pressure from the spring chamber32then decreases via the bores33, the chamber28, the control line27, the 3/2 way valve36and the channel38into the leakage steam line40. At the same time, the steam pressure on the complete front side of the quick-closing valve body19shifts the quick-closing valve2backwards into the spring chamber32until the spring sleeve21acovers the bores33and interrupts the steam flow to the leakage steam line40.

Just as in the opening process of the quick-closing valve2, now, here too, the damping zone is reached, and the pressure trapped in the spring chamber32then only slowly decreases via the gap until the tensioner22rests with its contact diameter Dkon the sleeve60and seals the spring chamber32. The quick-closing valve2has now again reached the end position “open”.

FIG.5shows a front view of the diffuser49. The swirl-breaking teeth54here, due to their uniform arrangement and shape, prevent the formation of eddies in the steam flow as the steam enters the diffuser49. The steam flow here is divided by the swirl-breaking teeth54at the border of the diffuser49. These divided streams thus cannot form large steam eddies and rejoin after the swirl-breaking teeth54to form a directed steam flow.

FIG.6shows a second embodiment of the combination valve1. The second embodiment differs with respect to the first embodiment in the design and mode of operation of the regulating valve3. All other reference signs remain the same in their function and position as in the first embodiment example ofFIGS.1to4, except for the sealing rings13which have been omitted here. The regulating valve drive8and the stem shaft10also correspond in their embodiment substantially to the first embodiment example.

In the second embodiment example, the regulating valve3is embodied as a pre-stroke regulating valve. Here, the regulating valve3comprises a tubular valve body64with a step65arranged on the inside of the tubular valve body64, a push body66, a pull body67and a tensioner68. The push body66has a centric bore69. The pull body67has pressure relief bores70.

The tubular valve body64is guided on the inside of the quick-closing valve body19. The sealing rings13are omitted, and as a result the labyrinth seal12now allows a small steam flow which reaches the step body72and ensures the function thereof. The push body66rests inside the tubular valve body64against the step65. The push body67rests against the pull body66. The tensioner68rests against the pull body67and secures the position of the push body66and of the pull body67. The pull body67is guided on the stem shaft10via a centric bore71.

For opening the regulating valve3, the stem shaft10travels backwards via the regulating valve drive8. Here, the step body72of the stem shaft10, after a short travel distance, rests against the pull body67and moves the tubular valve body64via the pull body67and the tensioner68.

For closing the regulating valve3, the stem shaft10travels forward by the regulating valve drive8. Here, the step body72of the stem shaft10, after a short travel distance, rests against the push body66. The stem shaft10then moves the tubular valve body64, by transmitting the force via the push body66and the step65, forward into the closed position. In the closed position, the tubular valve body64rests against the second sealing area52of the diffuser49.

Since such pre-stroke regulating valves have already existed since the 1960s and are described for example in Traupel, W.: “Thermische Turbomaschinen”, Springer-Verlag, 1982, and are known to the person skilled in the art, a detailed explanation will be dispensed with at this point. It should be clear, however, that this also applies to such pre-stroke regulating valves which have a different structure than the regulating valve shown inFIG.6.

FIG.7shows a side view of the spring sleeve21aand the tensioner22. The tensioner22is embodied with an external hexagon on one end face. The external hexagon has a flank distance which corresponds to a standardized wrench size. The surface of the external hexagon of the tensioner22is bulged. The bulge has a preferably line-shaped maximum in the contact diameter Dk.

The spring sleeve21ahas four axial grooves63. The axial grooves63are arranged uniformly at the circumference of the inner bore of the spring sleeve21a.The tensioner22is arranged in the inner bore of the spring sleeve21a.The tensioner22rests flat against the spring sleeve.

The axial grooves63function as flow channels and allow an equalization of pressure when the quick-closing valve is opened and closed. The design of the wrench head of the tensioner22as a hexagon and the number of axial grooves ensure here at least one at least partially bare flow channel, due to the geometry of the hexagon and the arrangement of the axial grooves63offset by 90° to each other. Pressure differences that cannot be equalized by a flow channel could lead to errors when opening and/or closing the quick-closing valve and thus negatively influence the function of the combination valve.