Valve assembly for hot gases

Abstract

A gate valve assembly (1) for hot pressurized gases, said gate valve assembly (1) comprising: a valve housing (2) having a first opening (2.10) with a first sealing seat (2.11) and an opposite second opening (2.20) with a second sealing seat (2.21), wherein both seats are opposing stationary sealing seats; a valve gate (3) comprising a blocking region (3.10) for blocking a gas path (2.0) between the first and second openings (2.10, 2.20), wherein the valve gate (3) is movably disposed within said valve housing (2) between a closed valve position, thereby blocking said gas path (2.0) and an open valve position wherein said blocking region (3.10) is in a position outside said gas path (2.0), wherein the blocking region (3.10) has a thickness smaller than the first distance; and wherein the valve gate (3) further comprises a lateral projections (3.21, 3.22) arranged on said peripheral edge (3.13) and wherein the valve housing (2) comprises clamping mechanisms (2.30, 2.40), each comprising a pivoting lever (2.31, 2.41) with a driver end (2.32, 2.42) configured for engaging one of said projections (3.21, 3.22) in the closed valve position, wherein the clamping actuators (2.34, 2.44) act on the pivoting levers (2.31, 2.41) to sealingly engage the blocking region against either of the first or second sealing seat (2.11, 2.21) in a sealed valve position.

Description

VALVE ASSEMBLY FOR HOT GASESTechnical fieldThe present invention generally relates to a valve assembly for hot gases, such as for example for use in a shaft furnace installation and more specifically to a valve assembly for use in a hot gas injection system in a shaft furnace.Background Art

[0001] With the Paris Agreement and near-global consensus on the need for action on emissions, it is imperative that each industrial sector looks into the development of solutions towards improving energy efficiency and decreasing CO2 output.

[0002] In this context, considerable efforts are being made to reduce the usage of carbonaceous fuel for the operation of shaft furnaces such as blast furnaces. Substitution of coke by other energy sources, mostly injected at tuyere level, is nowadays widely employed, and higher and higher amounts of hot gases mainly containing reducing species such as CO and H2 are injected in shaft furnaces.

[0003] Such reducing gases are commonly heated to very high temperatures, i.e. up to 1400 °C and even up to 1600 °C, in order to provide sufficient energy to the shaft furnace in addition to the reactive reducing species.

[0004] Any valve used to control the flow of such a hot reducing gas would thus be exposed to extreme conditions in that not only the temperature is very high, but also the pressure of the injected gas is high. Moreover, in such applications, the injected hot gas contains CO and H2, which may spontaneously inflame when leaking to the outside or may form an explosive atmosphere when mixed with air, so that the flow control valve should thus be totally gas-tight and leak-free in order to ensure safety of the shaft furnace installation.

[0005] Conventional hot blast valves (used for controlling the flow of injected hot blast in blast furnaces) may generally handle high pressures, i.e. up to about 6 bar, and very high temperatures, i.e. up to 1400 °C. However, these valves work only in one direction and they are not sufficiently gas-tight, as they commonly leaka hundred times more gas than what is desired and admissible for a reducing gas having a high concentration of e.g. H2 and / or CO.

[0006] A shut-off valve design for high temperatures and pressure has been proposed in EP 3 067 596 A1 , wherein the shut-off valve has a valve housing, a seat ring cage, which is mounted in a stationary manner in the valve housing, and a shut-off element arranged within the seat ring cage and adjustable by means of a drive. The seat ring cage is guided in a sealed manner in the valve housing in the area of its end facing away from the bearing in the valve housing, thereby ensuring an improved gas-tight sealing of the valve compared to conventional hot blast valve. However, such a valve was designed to resist to temperatures up to 1100 °C only.Technical problem

[0007] It is thus an object of the present invention to provide an improved design of a valve assembly for hot or even very hot gases, such as for use in a shaft furnace, having an improved gas-tightness, being able to withstand high pressures and very high temperatures, and having a reduced leakage.

[0008] This object is achieved by a gate valve assembly as claimed in claim 1 , a controlled gate valve assembly as claimed in claim 11 and a method for controlling the flow of hot pressurized gases according to claim 15.General Description of the Invention

[0009] In order to achieve this object, the present invention proposes, in a first aspect, a gate valve assembly for hot pressurized gases, said gate valve assembly comprising: a valve housing having a first opening and an opposite second opening; the first opening comprising a first sealing seat and the second opening comprising a second sealing seat, wherein both sealing seats are opposing stationary sealing seats arranged in parallel at a first distance of one another inside the valve housing; a valve gate comprising a blocking region, with a first side, a second side and a peripheral edge (connecting the first side to the second side), for blocking a gaspath between the first and second openings, wherein the valve gate is movably arranged within said valve housing (for moving) between a closed valve position wherein said blocking region is in alignment with said openings between the first and second sealing seats, thereby blocking said gas path and an open valve position wherein said blocking region is in a position outside said gas path, wherein the blocking region of the valve gate has a thickness smaller than the first distance; and wherein the valve gate further comprises a first lateral projection and a second lateral projection arranged on said peripheral edge and wherein the valve housing comprises a first clamping mechanism and a second clamping mechanism, each clamping mechanism comprising a pivoting lever with a driver end configured for engaging one of said first and second projections in the closed valve position and an opposite actuated end configured for being actuated by a clamping actuator, wherein the clamping actuators act on the pivoting levers to sealingly engage the blocking region against either of the first or second sealing seat in a sealed valve position.

[0010] Such a gate valve assembly is thus advantageously a perfectly gastight, leak-free valve assembly for conveying and controlling the flow of a pressurized hot to very hot gas, e.g. a reducing gas, such as a syngas or even pure hydrogen, or any other gas or mixture of gases. For example, such gate valve assemblies are ideal for pressures generally above about 2 bar, such as at least about 5 bar, preferably at least about 6 bar or more and / or temperatures generally above about 200 - 400 °C and up to about 1400 °C, preferably up to about 1500 °C, more preferably up to about 1600 °C or even above.

[0011] A merit of the invention is that such gate valve assemblies can be used for various applications, such as for controlling the flow of a gas for use in a blast furnace, a direct reduction reactor, ... , wherein a hot (at a temperature above at least 800 °C) gas (such as a combustible or reducing gas) is to be conveyed and controlled, as the sealing system with their fixed sealing seats allow for a safe and reliable shut-off and minimal leak rates of the gate valve assembly.

[0012] One of the problems addressed by the gate valve assembly according to the invention is thus that such valves are intended to be exposed to very harshand largely varying conditions of temperature, pressure and dust, which are challenging all attempts to provide gas-tight valves. Indeed, due to largely varying temperatures all parts undergo significant thermal expansion and contraction, which is especially detrimental to appropriate sealing for extended life-times. High pressures and dust only exacerbate the problems of gas-tightness. The gate valve assembly according to the invention therefore comprises two fixed sealing seats on the valve housing allowing for providing a perfectly planar and sturdy sealing seats. Thanks to its sealing in two steps, bringing the valve gate in a closed valve position wherein the valve gate is blocking the gas path between the first and second opening, yet without being gas-tight and then its bringing into a sealed valve position wherein the blocking region of the valve gate is pushed and pressed by the clamping mechanisms against one of the sealing seats. Hence, the gate valves of the invention basically have three working positions, an open valve position, wherein the blocking region of the valve gate is taken out of the gas path, providing an unhindered passage to the gas; a closed valve position wherein the blocking region of the valve gate is entirely obstructing the gas path, yet without being gastight, as small amounts of gas may still flow through the small gaps on either side between the blocking region and the sealing seats; and a sealed valve position, wherein the blocking region is sealingly applied against one of the fixed sealing seats. As will be explained later, although the blocking region could be pushed against any of the two sealing seats, it is particularly advantageous to press the blocking region to the sealing seat on the side of the lowest gas pressure, meaning that when and once the blocking region is in a sealing position, the pressure differential between the first and second opening will contribute to or enhance the sealing quality of the blocking region on the respective sealing seat by the forces of the gas pressure. Hence, the clamping mechanisms as such do not need to (permanently) provide for the required sealing pressure against the sealing seat, the sealing mechanisms can moreover be relatively simple by providing only few, e.g. two, positions for applying mechanical sealing pressure to the blocking region. Yet, this technical simplicity is further paired to the advantage that the clamping actuators, which may e.g. be electric actuators or pneumatic or hydraulic pistons, etc., due to their pivot levers can be placed at a certain distance from the gas path or even at the outside of the valve housing, which not only relieves them from (an essential) part of the thermal stress from the hot gas insidethe gas path, but also increases their reliability and accessibility for maintenance or replacement.

[0013] In fact, the sealing mechanisms used in the present invention make advantageous use of a pivoting lever to provide the required movement to the blocking region, while allowing for an advantageous placement of the clamping actuators, e.g. outside the valve housing. Such a pivoting action of the pivoting lever may be obtained by known methods, preferably however the pivoting lever is mounted on a spherical plain bearing acting as a pivot point, allowing for a tilting movement of the pivoting lever. Even in (the preferred) case when the clamping actuators are placed outside of the valve housing, due to the limited movements of the clamping mechanisms, a gastight sealing of any of its components can readily be obtained by known means, such as for example by providing the first and second clamping mechanisms with metal bellows, which may be sealingly attached and preferably welded in place for most reliable and long-lasting gas tightness.

[0014] Moreover, the two-step closing and sealing of the gate valve assembly of the invention, wherein the thickness of the blocking region is smaller than the (fixed) distance between the first and second sealing seats protects the sealing seals from damage (scrapes and scratches) during the closing and opening movement of the valve gate, while taking into account that due to the potentially huge temperature variations the dimensions, especially the thickness of the blocking region may significantly vary.

[0015] What is more, the gate valve assembly of the invention can be operated in both directions for the sealing, meaning that it can be sealingly gas tight whether the flow / pressure is from / on the side of the first opening or from / on the side of the second opening. Even in case the pressure differential abruptly changes, the sealed valve position can be switched from one sealing seat to the other almost instantly, either by control, or in case of sufficient pressure difference, automatically.

[0016] The movement of the valve gate from an open valve position to a closed valve position or vice-versa can be of any type, such as by rotation or translation or a combination thereof. Hence, in preferred embodiments, the valve gate isslidably and / or swingingly movable between the open valve position and the closed valve position, i.e. the valve gate can be moved solely through a (linear) sliding movement (i.e. a sliding valve), solely through a (arcuate) swinging movement (i.e. a swinging valve) or even through a combination of both movements. For dimensional and operational reasons, it may be advantageous to effect the opening and closing movements by a translational movement only. Hence, in particularly preferred embodiments, the valve gate is slidably movable between the open valve position and the closed valve position, i.e. the valve gate can be moved solely through a (linear) sliding movement (i.e. a sliding valve). In such cases, the first and second lateral projections are beneficially arranged on said peripheral edge of the blocking region, such as at opposite sides of the blocking region.

[0017] When the valve gate is in a closed valve position, it will be moved to a sealed valve position by the clamping mechanisms acting with their driver ends on the projections provided on the edge of the blocking region. The shape of the projections and the driver ends can be chosen among known solutions as long as the driver end is able to engage and laterally move the blocking region against the first or second sealing seats. Hence, the driver ends and said first and second projections, thus acting as followers, have (roughly) complementary shapes. In preferred embodiments, said driver ends have a U-shape, e.g. they are configured as U-shaped forks, and said first and second projections have an I or (inverted) T- shape, e.g. they are configured as I or T-shaped followers. Advantageously, the driver ends may have a projection-centering outline, meaning that their shape is such that the projections, during the closing of the valve gate, are centered within the driver ends of the clamping mechanism, e.g. with a V-shape in the moving / sliding / swinging direction. Hence, during the opening / closing movement, the valve gate may only be guided by static seats which prevent it from substantially moving along the axial axis. However, in or near the closed position, the driver end of the clamping system guides the T-shaped follower. Alternatively, or additionally, the valve housing may comprise guiding means, such as guiding rails or grooves, for guiding said first and second projections on the edge of the valve gate during opening and closing movements. Depending on the movement of the valve gate, such guiding means may be straight (e.g. for a sliding gate vale)or arcuate (e.g. for a swinging gate valve) This allows to further warrant that the blocking region remains at a controlled and safe distance between the first and second sealing seats at any time during movement of the valve gate.

[0018] To further enhance the reliability of the valve gate movement, it may be of benefit to provide the valve housing and / or the guiding means with end position abutments for limiting the movement of the valve gate in the open valve position and / or in the closed valve position.

[0019] The shape and size of the gas path within the present gate valve assemblies will generally adapt to the conducts in which it is intended to install such a flow control. Hence, often the first and second openings of the valve housing will have a circular cross-section, the blocking region of the valve gate is disc-shaped and the first and second sealing seats are circular. Of course, other shapes are possible, such as in particular polygonal, e.g. rectangular, rounded or oval.

[0020] While not mentioned yet, a huge advantage of the present invention is also the technical simplicity of the blocking region, which advantageously basically is a one-piece flat polygon or disc, as opposed to complex multipart assemblies known in the art. Indeed, such technically simple blocking regions are not only more reliable, but moreover are easily adaptable to an active cooling system, which is of particular relevance for very hot gases, such as at temperatures above 800 °C. Therefore, in advantageous embodiments, the valve gate and / or the blocking region comprise one or more cooling channels. The cooling channels are preferably provided within the blocking region, but they may also be foreseen in other parts of the valve gate, such as in the part linking the blocking region to a valve gate actuating mechanism. If necessary or desired, the valve housing may also be provided with a cooling system, e.g. cooling channels within the thickness of the housing.

[0021] The valve housing may be inserted within a gas path or conduct by any known means, such as by welding or affixing with bolts, etc. It generally is advantageous that the first and second openings are provided with respective mounting flanges, allowing the removable, yet gas-tight attachment to corresponding flanges on the gas conduct. The valve housing as such is gas-tight,e.g. as defined in the context of pressure containment and corresponding proof test in accordance with the relevant Pressure Equipment Directive 2014 / 68 / EU of 15 May 2014 and preferably comprises a gas purging system allowing to purge any gas contained within the valve housing or to inject any desired gas, such as for example cold and / or inert gas, e.g. for maintenance or in emergency situations. Alternatively or additionally, a gas purging system can be installed up or downstream the gate valve assembly, such as in case of two gate valve assemblies installed in series (e.g. in case of a double block and bleed arrangement).

[0022] In addition, or alternatively to being actively cooled, the valve housing may comprise a refractory lining within its gas path to protect the (uncooled) metal parts from the action of the hot / aggressive gas, and / or it can be insulated, thereby further protecting operators working in the proximity of the valve assembly from the high temperature of the gas flowing through the valve assembly. In most preferred embodiments, the housing can withstand high pressures, e.g. up to 5- 6 bar, high temperatures (e.g. up to at least 1400 °C) and high mechanical stress (e.g. up to 9 MN).

[0023] The valve housing may comprise removable cover(s) on one or more of its sides. Such a removable cover may be used as entry port for facilitating inspection and / or maintenance operations.

[0024] In a second aspect, the invention proposes a controlled gate valve assembly (configured) for controlling the flow of hot pressurized gases, comprising a gate valve assembly according to the first aspect of the invention, and additionally comprising: a first pressure sensor configured for measuring a first gas pressure to the side of the first opening and a second pressure sensor configured for measuring a second gas pressure to the side of the second opening, a control unit connected to said first and second pressure sensors and to the clamping actuators of said first and second clamping mechanisms, wherein the control unit is configured for controlling the clamping actuators when the valve gate is in a closed valve position, to sealingly engage the blocking region of the valve gate against the sealing seat of the valve housing, in the sealed valveposition, on the side of the first and second openings with the lowest gas pressure among first and second gas pressures.

[0025] The first and second pressure sensors may be installed directly in the valve housing within the gas path, e.g. within or near the first and second openings (i.e. on either side of the valve gate / blocking region), or they may be installed within the gas conduct further up- and downstream of the gate valve assembly. Indeed, when the valve gate is moved from an open valve position to a closed valve position, although the valve isn’t entirely blocking the gas flow (as some gas may still flow around the blocking region through the remaining distance between each sealing seat and the blocking region), a pressure differential between upstream and downstream gas conduct will build up and this pressure difference (or the separately measured up- and downstream pressures themselves) may be used to determine whether to sealingly press the blocking region to the first sealing seat or to the second sealing seat. While basically both options would work, the advantage of sealingly pressing the blocking region to the sealing seat on the side of the lowest pressure has the advantage of allowing to use the forces of the pressure difference itself to assist the sealing action of the clamping mechanisms. This thus not only provide for a more uniformly applied sealing force to the blocking region onto the sealing seats, but also serves as a passive sealing of the blocking region (i.e. not requiring the clamping mechanisms to continue to keep the blocking region in sealing contact with the sealing seats) depending on the pressure difference.

[0026] The clamping mechanism may feature one or more position sensors, such as analogic position sensors, which allow(s) the control unit to determine or measure the actual position of the clamping actuator. Advantageously, it also allows the control unit to stop the clamping actuator in their idle position before sealingly engaging the valve gate in its sealed valve position or releasing the valve gate to its closed valve position. This not only ensures that valve gate is in its intended position, but also to safeguard the valve gate and especially the sealing seats of the valve housing and the sealing region of the valve gate are not damaged, i.e. through scratching, during the opening and closing.

[0027] The valve gate can be moved from its open valve position to its closed valve position by any know means, such as by a rod or the like that extends to theoutside of the valve housing and is actuated hydraulically, pneumatically, electrically, manually, or any combination thereof. Preferably, the controlled gate valve assembly comprises one or more valve gate actuator(s), which may e.g. be electric actuators or pneumatic or hydraulic pistons, etc., configured for moving said valve gate between the open valve position and the closed valve position and vice-versa, wherein the control unit is further configured for controlling the movement of the valve gate through the control of the valve gate actuator. In such embodiments, it becomes possible to fully automate the control of the gate valve assembly and / or to integrate it in an existing automation (which could then take over the role and functions of the control unit).

[0028] As already hinted at above, it may be advantageous or desirable to more reliably know the open or closed state / position of the gate valve assembly. Hence, in embodiments, the controlled gate valve assembly may further comprise open valve gate and / or closed valve gate detecting means, which are preferably connected to said control unit, said control unit being configured for detecting whether said valve gate is in the open valve position or in the closed valve position. These detecting means may be placed at appropriate positions within the valve housing, such as on the guiding means or the corresponding abutments, etc. Moreover, the control unit connected to said open valve gate and / or closed valve gate detecting means may be further configured for controlling the movement of the valve gate through the control of the valve gate actuator.

[0029] The present invention also considers a method for controlling the flow of hot pressurized gases, using a gate valve assembly according to the first aspect or a controlled gate valve assembly of the second aspect, wherein control of a pressurized gas is effected by moving the valve gate from an open valve position into a closed valve position, preferably through the control and action of one or more valve gate actuator(s), and then, once the blocking region / valve gate is in the closed position, by moving it into a sealing position by pressing the blocking region of the valve gate against one of the first or second sealing seats; or by releasing the blocking region from the sealing seats into the closed position and then, once the blocking region / valve gate is back in the closed position, by moving the valve gate from the closed valve position into the open valve position, preferably through the control and action of one or more valve gate actuator(s).Brief Description of the Drawings

[0030] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:Fig. 1 is a perspective cross-sectional view through the center of a preferred embodiment of a gate valve of the invention, wherein the valve gate in an open valve position;Fig. 2 is a perspective partial view of a cross-section of the preferred embodiment shown in Fig. 1 , but with the valve gate in a closed valve position;Fig. 3 is a cross-sectional detail view of the clamping mechanism used in Fig. 1 and 2, wherein the valve gate in a closed valve position;Fig. 4 is a further cross-sectional detail view of the clamping mechanism of Fig. 3, wherein the valve gate in a sealed valve position;Fig. 5 is a front view of a preferred embodiment of the valve gate as shown in Fig. 1 to 4;Fig. 6 is a partial perspective view showing more particularly an embodiment of a lateral projection;Fig. 7a is a cross-sectional schematic side view of an embodiment of a controlled gate valve of the invention with a control unit, wherein the valve gate in a closed valve position;Fig. 7b is a cross-sectional schematic side view of another embodiment of a controlled gate valve of the invention with a control unit, wherein the valve gate in a closed valve position;Fig. 8a is a cross-sectional schematic front view of a still further embodiment of a controlled gate valve of the invention with a control unit, wherein the valve gate in its open valve position;Fig. 8b is the corresponding cross-sectional schematic front view of the controlled gate valve of Fig. 8a, wherein the valve gate in its closed or sealed valve position;Fig. 9a is a cross-sectional schematic front view of a still further embodiment of a controlled gate valve of the invention with a control unit, wherein the valve gate in its open valve position; andFig. 9b is the corresponding cross-sectional schematic front view of the controlled gate valve of Fig. 9a, wherein the valve gate in its closed or sealed valve position.

[0031] Further details and advantages of the present invention will be apparent from the following detailed description of several not limiting embodiments with reference to the attached drawings.Description of Preferred Embodiments

[0032] In the attached drawings, the same features are represented by the same reference. However, due to the type of the views, not all references will be shown (because they are part of the missing cross-section) or visible (because they are hidden by other features in the drawing).

[0033] As mentioned, Fig. 1 is a perspective cross-sectional view through the center of the valve housing 2 of a preferred embodiment of a gate valve 1 , wherein the valve gate 3 is in an open valve position. Fig. 2 is a perspective partial view of a cross-section of the preferred embodiment shown in Fig. 1 , but with the valve gate 3 with its blocking region 3.10 in a closed valve position, i.e. now blocking the gas path 2.0. For the valve housing 2, this cross-section may actually represent one of two essentially identical or mirrored parts that can easily be (dis)assembled. Furthermore, the first and second openings 2.10, 2.20 of the valve housing 2 may advantageously be provided with respective mounting flanges 2.60 for mounting the gate valve 1 into a gas conduct.

[0034] In the open valve position, the valve gate 3 with its blocking region 3.10 actuatable through actuating members 3.30 (partially shown) is retracted from the gas path 2.0 formed between the first opening 2.10 (not shown) and the second opening 2.20.

[0035] The blocking region 3.10 comprises a first (front) side 3.11 (not shown), a second (back) side 3.12 (not visible) with a peripheral edge 3.13 joining said first and second sides 3.11 , 3.12. On the peripheral edge 3.13 are mounted a first lateral projection 3.21 and a second lateral projection 3.22 configured for engaging into the driver ends 2.42 of the respective first and second clamping mechanisms 2.30, 2.40, once the valve gate 3 is in the closed valve position (see Fig. 2). It is to be noted that if the blocking region is not disc-shaped as in Fig. 1 , more lateral projections could be appropriate or desirable, such as e.g. four (e.g. two in anupper portion and two in a lower portion) in the case of a(n essentially) rectangular blocking region. The valve gate 3 and more particularly the blocking region 3.10 are preferably provided with a cooling system, such as cooling channel(s) 3.50. These cooling channels 3.50 may be provided in a double front-to-back spiral pattern as depicted in the drawings or any other appropriate configuration depending on the required or desired cooling capacity and / or the shape and thickness of the blocking region 3.10.

[0036] The valve housing may further comprise guiding means, such as guiding rails or grooves (2.50 indicates the position of such optional guiding rails or grooves) configured for guiding the lateral projections 3.21 , 3.22 during its movements from the open valve position to the closed valve position or back. At one or both ends of these guiding means, corresponding abutments may be provided to precisely limit the movement of the valve gate 3. Furthermore, corresponding end or intermediate detecting means, such as limit switches, may be provided to detect the position of valve gate 3.

[0037] Each opening 2.10, 2.20 within the gas path 2.0 comprises a respective (first or second) fixed sealing seat 2.11 (not shown) and 2.21. The opposing sealing seats are at a (uniform) distance of one another, said distance being (slightly) greater than the thickness of the blocking region, thereby forming a gap or clearance on each side in the closed valve position as will be explained more in detail below in relation with the clamping mechanisms 2.30, 2.40.

[0038] As can be seen more particularly in Fig. 2, the first and second lateral projections 3.21 , 3.22 of the blocking region 3.10 are now engaged within or around (depending on their shape) the respective driver end 2.32, 2.42 of the pivoting levers 2.31 , 2.41. Although not clearly visible in Fig. 2, the clamping mechanisms are in their idle position, meaning that the pivoting levers 2.31 , 2.41 are in their neutral (non-pivoted) position, wherein the blocking region 3.10 of the valve gate 3 is (essentially) centered between the first and second sealing seats 2.11 , 2.21 , with a gap 3.112, 3.122 on each side as shown more in detail in Fig. 3.

[0039] The valve housing may further comprise one or more gas purging ports / systems and / or condensate drainage ports 2.70. While the gas purging ports may be place in a number of locations of the housing for purging the valvehousing, condensate drainage ports are located at a lowermost point in the valve housing or at different locations where condensate may accumulate.

[0040] Fig. 3 is a cross-sectional detail view of the clamping mechanism used in Fig. 1 and 2, wherein the valve gate in a closed valve position; whereas Fig. 4 is a further cross-sectional detail view of the clamping mechanism of Fig. 3, wherein the valve gate in a sealed valve position.

[0041] The position of the blocking region 3.10 in Fig. 3 corresponds to that in Fig. 2, meaning that the blocking region is in a closed valve position, but it is not yet sealingly applied to one of the sealing seats 2.11 , 2.21. Hence, on each side of the blocking region 3.10 at its peripheral first and second sealing regions 3.111 , 3.121 there is a first and second gap 3.112, 3.122, respectively. These gaps allow for some limited gas passage, hence the gate valve in its closed valve position does not yet obturate entirely the gas flow in the gas path 2.0. As can be seen, the pivoting lever 2.31 is in its idle (non-pivoted) position around pivoting axis 2.35 and the driver end 2.32 is (loosely) engaged with a (here the first) lateral projection 3.21 of the blocking region 3.10. The clamping actuator 2.34 (here placed outside the valve housing) configured to act on the actuated end 2.33 of the pivoting lever 2.31 is also in its idle position.

[0042] Now regarding the second step of the closing-sealing sequence, reference is made to Fig. 5, which is a (more limited) view similar to that of Fig. 4, but once the blocking region 3.10 is in a sealed valve position. This is obtained through the action of clamping actuator 2.34 (not shown in Fig. 4) which pulled on the actuating end 2.33 of the pivoting lever 2.31 , thereby pushing the peripheral first sealing region 3.111 of the blocking region 3.10 against the first sealing seat 2.11 and sealingly closing the first gap 3.122.

[0043] Conversely, if the clamping actuator 2.34 had been actuated to push on the actuated end 2.33 of the pivoting lever 2.31 , the driver end 2.32 would have moved the blocking region 3.10 with its second sealing region 3.121 against the second sealing seat 2.21 , thereby sealingly closing the second gap 3.122.

[0044] Fig. 3 and 4 also show the bellow assembly 2.36 allowing to hermetically close the clamping mechanism 2.30, thereby permitting the placement of the clamping actuators outside the valve housing 2. In the shown embodiment thebellow assembly allows for ensuring that the area around the gate valve assembly is not classified as ATEX (explosive atmosphere) according to the ATEX Directives (Directive 2014 / 34 / EU and / or Directive 1999 / 92 / EC).

[0045] Fig. 5 and 6 show the valve gate 3 with its blocking region 3.10 and its actuating members 3.30 as shown in Fig. 1 to 4 in a front view, respectively as a partial perspective view of an embodiment of a (second) lateral projection 3.22.

[0046] The drawings show the first (front) side 3.11 with its peripheral first sealing region 3.111 , its edge peripheral 3.13 joining the (back) second side 3.12 of the blocking region 3.10 with a corresponding second sealing region 3.121 (not visible). On each side of the blocking region 3.10 are provided first and second lateral projections 3.21 , 3.22, which, as shown in Fig. 6, may be screwed to the edge 3.13 of the blocking region 3.10 or they may be attached in another appropriate way, such as by welding.

[0047] Fig. 7a and 7b show cross-sectional schematic side views of controlled gate valves of the invention with a control unit 4, wherein the valve gate in a closed valve position. In this schematic embodiment, a first pressure sensor 4.10 is provided in the upstream gas conduct 5.10, whereas a second pressure sensor 4.20 is installed in the downstream gas conduct 5.20. Based on the measurement of both sensors 4.10 and 4.20, the control unit 4 determines to which sealing seat of the gate valve housing the sealing region of the valve gate should be pressed by the clamping mechanisms to provide a sealing contact in the sealed valve position.

[0048] The open and / or the closed position of the valve gate may be determined by the control unit 4 through open valve detecting means 4.40 and / or closed valve detecting means 4.45. Advantageously those open and / or closed valve detecting means 4.40, 4.45 are installed outside of the valve housing in order not to be exposed to the harsh conditions inside the housing and for easy accessibility during maintenance and replacement.

[0049] Now, Fig. 8a, 8b, 9a and 9b show a cross-sectional schematic front view of controlled gate valves of the invention with a control unit 4, wherein the valve gate in their open valve position in Fig. 8a and 9a and in their closed or sealed valve position in Fig. 8b and 9b. These schematic embodiments essentiallycorrespond to that of Fig. 7a and 7b seen from an axis parallel to up- and downstream gas conducts 5.10, 5.20. As in Fig. 7a and 7b, the open and / or the closed position of the valve gate may be determined by the control unit 4 through open valve detecting means 4.40 and / or closed valve detecting means 4.45. Furthermore, the clamping mechanisms include clamping actuators and position sensors 4.50 such that control unit 4 may determine at any desirable time the position of the clamping mechanism and / or of the clamping actuator and / or of the driver end and / or of the actuated end of the pivoting lever.

[0050] Fig. 7b, 9a and 9b further show an end position abutment 4.60 for the valve gate in open valve position and an end position abutment 4.65 for the valve gate in closed valve position. Furthermore, a purging line outlet 4.70 is provided for in the valve housing.Legend:1 Gate valve assembly2 Valve housing2.0 Gas path2.10 First opening2.11 First sealing seat2.20 Second opening2.21 Second sealing seat2.30 First clamping mechanism2.31 Pivoting lever2.32 Driver end2.33 Actuated end2.34 Clamping actuator2.35 Pivoting axis2.36 Bellow assembly2.40 Second clamping mechanism2.41 Pivoting lever2.42 Driver end2.43 Actuated end2.44 Clamping actuator2.45 Pivoting axis2.46 Bellow assembly2.50 Position of optional guiding rails or grooves2.51 End position abutment in open valve position2.52 End position abutment in closed valve position2.60 Mounting flange(s)2.70 Gas purging system and / or condensate drainage port3 Valve gate3.10 Blocking region3.11 First side3.111 First sealing region3.112 First gap3.12 Second side3.121 Second sealing regionSecond gap Peripheral edge First lateral projection Second lateral projection Actuating member Cooling channel(s) Control unit First pressure sensor Second pressure sensor Valve gate actuator Open valve gate detecting means Closed valve gate detecting means Clamping actuator and position sensor End position abutment in open valve position End position abutment in closed valve position Purging line outlet Upstream gas conduct Downstream gas conduct

Claims

Claims1 . A gate valve assembly (1 ) for hot pressurized gases, said gate valve assembly (1 ) comprising: a valve housing (2) having a first opening (2.10) and an opposite second opening (2.20); the first opening (2.10) comprising a first sealing seat (2.11 ) and the second opening (2.20) comprising a second sealing seat (2.21 ), wherein both sealing seats are opposing stationary sealing seats arranged in parallel at a first distance of one another inside the valve housing (2); a valve gate (3) comprising a blocking region (3.10), with a first side (3.11 ), a second side (3.12) and a peripheral edge (3.13), for blocking a gas path (2.0) between the first and second openings (2.10, 2.20), wherein the valve gate (3) is movably disposed within said valve housing (2) between a closed valve position wherein said blocking region (3.10) is in alignment with said openings (2.10, 2.20) between the first and second sealing seats (2.11 , 2.21), thereby blocking said gas path (2.0) and an open valve position wherein said blocking region (3.10) is in a position outside said path between the first and second openings (2.10, 2.20), wherein the blocking region (3.10) has a thickness smaller than the first distance; and wherein the valve gate (3) further comprises a first lateral projection (3.21) and a second lateral projection (3.22) arranged on said peripheral edge (3.13) and wherein the valve housing (2) comprises a first clamping mechanism (2.30) and a second clamping mechanism (2.40), each comprising a pivoting lever (2.31 , 2.41 ) with a driver end (2.32, 2.42) configured for engaging one of said first and second projections (3.21 , 3.22) in the closed valve position and an opposite actuated end (2.33, 2.43) configured for being actuated by a clamping actuator (2.34, 2.44), wherein the clamping actuators (2.34, 2.44) act on the pivoting levers (2.31 , 2.41 ) to sealingly engage the blocking region against either of the first or second sealing seat (2.11 , 2.21 ) in a sealed valve position.

2. The gate valve assembly (1 ) as claimed in claim 1 , wherein the valve gate is movable by a sliding movement or a swinging movement or a combination of those movements between an open valve position and a closed valve position, the first and second lateral projections (3.21 , 3.22) preferably being arranged on said peripheral edge (3.13) at opposite sides of the blocking region (3.10).

3. The gate valve assembly (1 ) as claimed in any of claims 1 or 2, wherein the driver ends (2.32, 2.42) and said first and second projections (3.21 , 3.22) have complementary shapes, preferably said driver ends (2.32, 2.42) are configured as U-shaped forks and said first and second projections (3.21 , 3.22) are configured as T-shaped followers.

4. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the pivoting lever (2.31 , 2.41 ) is mounted on a spherical plain bearing acting as a pivot point, allowing for a tilting movement of the pivoting lever (2.31 , 2.41 ).

5. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the first and second clamping mechanisms (2.30, 2.40) comprise a metal bellow.

6. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the first and second openings (2.10, 2.20) of the valve housing (2) have a circular cross-section, the blocking region (3.10) of the valve gate (3) is disc-shaped and the first and second sealing seats (2.11 , 2.21) are circular.

7. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the valve gate (3) comprising one or more cooling channels (3.50).

8. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the first and second openings are provided with respective mounting flanges (2.60).

9. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the valve housing (2) is gas-tight and comprises a gas purging system and / or a condensate drainage port (2.70) and / or a cooling system.

10. The gate valve assembly (1) as claimed in any of the preceding claims, wherein the valve housing (2) comprises end position abutments (2.51 , 2.52) for limiting the movement of the valve gate (3) in an open valve position and / or in a closed valve position, the valve housing (2) preferably also comprises guiding means for guiding said first and second projections (3.21 , 3.22) of the valve gate (3).

11. A controlled gate valve assembly for controlling the flow of hot pressurized gases, the controlled gate valve assembly comprising: a gate valve assembly (1 ) as claimed in any of claims 1 to 10, a first pressure sensor (4.10) configured for measuring a first gas pressure to the side of the first opening (2.10) and a second pressure sensor (4.20) configured for measuring a second gas pressure to the side of the second opening (2.20), a control unit (4) connected to said first and second pressure sensors (4.10, 4.20) and to the clamping actuators (2.34, 2.44) of said first and second clamping mechanisms (2.30, 2.40), wherein the control unit (4) is configured for controlling the clamping actuators (2.34, 2.44, 4.50) when the valve gate (3) is in a closed valve position, to sealingly engage the blocking region (3.10) of the valve gate (3) against the sealing seat (2.11 , 2.21 ) of the valve housing (2), in the sealed valve position, on the side of the first and second openings with the lowest gas pressure among first and second gas pressures.

12. The controlled gate valve assembly as claimed in claim 11 , further comprising a valve gate actuator (4.30) configured for moving said valve gate (3) between the open valve position and the closed valve position and vice-versa, wherein said control unit (4) is further configured for controlling the movement of the valve gate (3) through the control of the valve gate actuator (4.30).

13. The controlled gate valve assembly as claimed in claims 11 or 12, further comprising: open valve gate and / or closed valve gate detecting means (4.40, 4.45) connected to said control unit (4), said control unit (4) being configured for detecting whether said valve gate (3) is in the open valve position or in the closed valve position.

14. The controlled gate valve assembly as claimed in claims 13, wherein said control unit (4) connected to said open valve gate and / or closed valve gate detecting means (4.40, 4.45) is further configured for controlling the movement of the valve gate (3) through the control of the valve gate actuator (4.30).

15. A method for controlling the flow of hot pressurized gases, using a gate valve assembly as claimed in any of claims 1 to 10 or a controlled gate valve assembly as claimed in any of claims 11 to 14, wherein control of a pressurized gas is effected by moving the valve gate from an open valve position into a closed valve position, preferably through the control and action of one or more valve gate actuator(s), and then, once the blocking region / valve gate is in the closed position, by moving it into a sealing position by pressing the blocking region of the valve gate against one of the first or second sealing seats; or by releasing the blocking region from the sealing seats into the closed position and then, once the blocking region / valve gate is back in the closed position, by moving the valve gate from the closed valve position into the open valve position, preferably through the control and action of one or more valve gate actuator(s).

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