Valve assembly for hot gases
The valve assembly addresses the challenge of maintaining gas-tightness in extreme conditions by using a clamping unit with unclamped devices and a rotating flow control body, ensuring reduced leakage and improved maintenance in controlling hot reducing gases.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PAUL WURTH SA
- Filing Date
- 2026-01-07
- Publication Date
- 2026-07-23
AI Technical Summary
Existing valve assemblies for controlling the flow of hot reducing gases in shaft furnaces face challenges in maintaining gas-tightness under high pressures and temperatures, with conventional designs leaking significantly and failing to withstand extreme conditions.
A valve assembly with a clamping unit that includes movable clamping devices, which are unclamped during rotation to prevent frictional damage and ensure gas-tightness, combined with a flow control body that rotates between open and closed positions, using seals and hydraulic actuators for precise control and sealing engagement.
The design provides a leak-free and reliable valve assembly capable of withstanding high pressures and temperatures, reducing leakage, and facilitating easier maintenance, while ensuring safety and efficiency in controlling the flow of hot gases.
Smart Images
Figure EP2026050171_23072026_PF_FP_ABST
Abstract
Description
VALVE ASSEMBLY FOR HOT GASESTechnical Field
[0001] The 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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 leak a 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.
[0007] Alternative designs of gas valves are known e.g. from US 3,901 ,474 A, US 6,378,841 B1 and CN 211 550600 U wherein valve seats are provided for ensuring gas-tightness of the valve between a casing and a rotating plug, and are actuated, e.g. by means of hydraulic means, when the plug is to be rotated. Such designs however suffer the same drawbacks as conventional hot blast valves and they commonly leak a 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.
[0008] A shut-off valve design for high temperatures and pressure has been proposed in EP 3067596 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 shutoff 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
[0009] 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.
[0010] This object is achieved by a valve assembly as claimed in claim 1. General Description of the Invention
[0011] The present invention provides a valve assembly for an industrial plant, said valve assembly comprising:- a gas-tight (valve) housing with a first flow opening arranged in a first lateral side thereof and a second flow opening arranged in a second lateral side thereof;- a clamping unit comprising a first clamping device with a first sealing seat and a second clamping device with a second sealing seat, the clamping devices being respectively arranged at the first and second flow openings; and- a valve insert arranged within said (valve) housing between said first and second flow openings,wherein said valve insert comprises:- a bearing unit comprising at least two bearings and a shaft rotatable around a rotation axis of the bearing unit;- a flow control body comprising a blocking region for blocking a path between the flow openings and a pass-through region for opening said path; the flow control body being rotatable around the rotation axis of the bearing unit between a closed position, wherein the blocking region is in alignment with the flow openings and an open position, wherein the pass-through region is in alignment with the flow openings;- the flow control body further comprising first and second seals, respectively disposed on the blocking region and the pass-through region, the first seal being arranged to sealingly engage the first and second sealing seats of the clamping unit in the closed position of the flow control body and the second seal being arranged to sealingly engage the first and second sealing seats of the clamping unit in the open position of the flow control body;wherein each clamping device is movable between a clamped position in both the open and closed position of the flow control body, the clamped position being a rest position sealingly engaging the seal seats of the clamping devices and the first or second seals of the flow control body, and an unclamped position being an active position during rotation of the flow control body.
[0012] Such a valve assembly is 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 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.
[0013] One of the problems addressed by the valve assembly according to the invention is thus that such valves are intended to be exposed to very harsh and largelyvarying 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.
[0014] One of the merits of the invention is for the inventors to have realized that gas tightness might be safely ensured / enforced by a properly designed clamping unit. In fact, the clamping devices of such a clamping unit are configured to be actively unclamped, i.e. unclamped under tension during rotation of the flow control body, while being in a clamped rest position when the valve assembly is in use for regulating the flow of a gas. In other words, the invention is based on the use of unclamping devices, i.e. devices that stay clamped in the absence of actuation thereof. That is to say, each clamping device presents an inactive clamped configuration, and is unclamped solely upon I during action thereon. Hence the clamping devices as such do not need to (permanently / actively) provide for the required sealing pressure against the sealing seat.
[0015] Thus, the clamping device is configured to essentially have two operating positions: in a clamped position (i.e. rest position or inactive configuration), the sealing seats are pressed against the seals of either the first or second plurality of seals, and in an unclamped position the sealing seats are not pressed against the seals, thereby allowing easy movement (i.e. rotation) of the flow control body between its open and closed positions.
[0016] As understood by the skilled person, a seal is an additional part or piece, distinct from the flow control body but arranged and secured thereon, for sealingly engaging a respective sealing seat of the clamping unit.
[0017] Another merit of the present invention is that the flow control body is displaceable between its closed and open position by rotation around a rotation axis, i.e. is rotatable between its open and closed positions. Such a valve assembly advantageously has reduced spatial dimensions, in particular lateral and / or vertical dimensions, with respect conventional valve such as sliding valves and goggle valves. Further advantageously, access to elements located inside the (valve) housing is facilitated, such as access to the pass-through section of the flow control body, therebyallowing for easier inspection and / or maintenance operation thereof. Furthermore, the pass-through section of the valve insert of the present valve assembly is typically longer that e.g. for a sliding valve, such that it is possible to line it with heat-resistant material, such as e.g. a refractory material, in order to protect it, which increases the service time of the valve assembly.
[0018] Yet another merit of the present invention is that the clamping devices may be unclamped, i.e. moved toward their respective unclamped position, prior to rotating the flow control body. Such an unclamping operation advantageously provides some space (typically about a few mm, such as 2 or 3 mm or more) between the sealing seats of the clamping devices and the seals of the first or second plurality of seals of the flow control body, thereby providing some space between the clamping unit and the flow control body. This advantageously avoids occurrence of frictional forces onto the seals arranged on either the blocking region and pass-through region of the flow control body and thus efficiently prevents damages to the seals. The provided space, facilitating the rotation of the flow control body, not only further allows for a smoother and more precise movement of the flow control body, but also for a faster action of the valve assembly.
[0019] Advantageously, as the sealing seats of the clamping devices sealingly engage either the first or the second plurality of seals of the flow control body in the open or closed position, the sealing seats are formed separate from the valve housing, i.e. formed as separate elements. Thus, thermal deformations of the valve housing have only limited impact on the sealing seats, which greatly improves the reliability of the sealing.
[0020] Preferably, the sealing seats are designed as cone to sphere contact which can advantageously accommodate some displacement (e.g. due to thermal expansion in use).
[0021] Still another merit of the invention is that the valve assembly 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) combustible gas (preferably a reducing gas) is to be injected, as the sealing systems with the unclamping units allow for a safe shut-off and minimal leak rate of the valve assembly. Accordingly, the industrial plant is preferably an iron and / or steelmaking plant such that the valve assembly is configured for controlling a flow of gas, preferably a hot reducing gas.
[0022] Advantageously, the valve assembly may comprise further additional seals respectively arranged between the clamping devices of the clamping unit and the gas-tight housing, so as to further ensure the gas-tightness of the assembly and further prevent any gas leakage, e.g. during rotation of the flow control body (i.e. when the clamping devices are in their respective unclamped position).
[0023] In embodiments, at least one, and preferably both, of the clamping devices comprise(s) a (preferably metal) bellow (also sometimes referred to as bellow seal). Such a bellow advantageously increases the gas-tightness of the valve assembly. The bellow further advantageously compensates misalignment or tilting of the flow control body, which may occur in use because of thermal expansion due to the high to very high temperature (such as up to 1400 °C, preferably up to 1500 °C, more preferably up to 1600 °C or even above) of the gas flowing through the valve assembly. The below(s) is (are) thus preferably arranged and configured for preventing leakage of the valve assembly. Bellows may be welded in place for most reliable and long-lasting gas tightness.
[0024] In preferred embodiments, each clamping device is moved from the clamped position to the unclamped position by means of an actuating mechanism. Advantageously, in the absence of actuating power (e.g. electrical or mechanical power) to move a clamping device from its clamped to its respective unclamped position, the first and second sealing seats of the sealing unit respectively engages the seals of the first or second plurality of seals, i.e. the valve assembly is sealed (gastight, leak-free) in either its open position or its closed position. Overall safety of the valve assembly is increased, as the valve assembly would remain gas-tight and leak-free even in case of a power shortage or outage. Moreover, as clamping unit need power solely for moving the clamping devices toward their unclamped position during rotation of the flow control body, the power source may be turned off when gas is to flow through the valve assembly or when the flow of gas is to be interrupted (e.g. during maintenance operation of the valve assembly or of the furnace into which gas flowing through the valve assembly is injected), thereby reducing power consumption and reducing costs.
[0025] In such embodiments, the actuating mechanism of each clamping device may be mounted with a static seal so as to prevent gas leakage.
[0026] In embodiments, each clamping device may be passively pretensioned against a respective seal of the flow control body (seal of the first plurality in the open position of the valve assembly, seal of the second plurality in the closed position of the valve assembly). For instance, the clamping device may be (passively) pretensioned by at least one spring element acting on a rod which in turn exerts a force on the sealing seat. By this pretensioning, the sealing effect can be further enhanced. In such embodiments, the actuating mechanism creates a force opposite to the pretensioning force e.g. created by the at least one spring element.
[0027] The actuating mechanism may be any appropriate electrical, pneumatic and / or hydraulic mechanism comprising number of actuators. Preferably, a suitable actuating mechanism may be a hydraulic mechanism, such as a hydraulic mechanism comprising a plurality of parallel-acting actuators, such as hydraulic pistons. The number of actuators strongly depends on the seat load, the dimensions of the actuators (in particular the cylinder bore diameter of a hydraulic piston) and the required tightness. Each actuator preferably has a seat load of about 100 N / mm to 1000 N / mm. Such actuators, e.g. hydraulic pistons, advantageously put a constant force on the body in its respective seat to ensure the gas tightness of the valve assembly. To ensure an even load distribution, it may generally be required to use at least 6 (evenly distributed) actuators / hydraulic pistons.
[0028] Advantageously, any additional movement of clamping unit, e.g. the first and second sealing seats, once the valve assembly is pressurized in use I during utilization, may be absorbed by a hydraulic buffer provide in the hydraulic mechanisms, e.g. by hydraulic actuators or pistons. In other words, the hydraulic mechanisms allow for a sufficient backlash of the clamping unit, absorbing forces due to pressurization and / or thermal expansion of the valve assembly (e.g. of the housing or the flow control body), and preventing unintentional unsealing of one or both of the clamping device. Gas leakage is further prevented.
[0029] As already mentioned above, the hydraulic mechanism ensures that the valve assembly is gas-tight and leak-free. The sealing surfaces of the body and respective seat are to be well defined and complementarily shaped so as to ensure acontinuous, constant load over the whole periphery of the body / seat. In other words, the load applied by the hydraulic mechanism is uniform over the periphery of the seat.
[0030] The load distribution is preferably kept constant by using a high number of actuators (e.g. hydraulic pistons). The actuating mechanism may also comprise stiff spacers arranged between the hydraulic pistons and the sealing surface to help distributing the load even more. Additionally or alternatively, the sealing surface may be flushed with a flow of nitrogen so as to remove as much dust as possible and further increase the sealing between the various parts of the valve assembly.
[0031] The hydraulic pistons of the plurality of hydraulic pistons may be configured for being actuated separately. It is however preferred that they are configured for being actuated simultaneously. Simultaneous actuation of the plurality of hydraulic pistons advantageously facilitates control and even repartition of the forces around the whole periphery of the seat. As an alternative or in addition to the hydraulic mechanism, a pneumatic, electrical and / or manual mechanism may also be envisaged.
[0032] The two clamping devices may be unclamped and / or clamped separately or simultaneously. It is however preferred that the two clamping devices are simultaneously moved from one clamped / unclamped position to the other unclamped / clamped position. Simultaneous operation (i.e. displacement from one position toward the other) of the two clamping devices advantageously ensure that all seals of one plurality of seals are in the same position (i.e. sealing engaging the respective sealing seats of the clamping devices or being distant therefrom) at the same time, thereby increasing the safety of the valve assembly by preventing any gas leak due to one seal being mistakenly in an unsealing position (i.e. distant from its respective seat) while the other seal(s) of the respective plurality of seals is in a sealing position, or vice versa.
[0033] It is however still within the scope of the present invention to operate (i.e. move from the clamped position toward the unclamped position or conversely from the unclamped position toward the clamped position) the clamping devices separately from one another, as it may also be of advantage to unseal only one seal of a given plurality of seals, e.g. for maintenance operation, to verify the state of only one sealingseat or only one seal, or to change only one of the seals of the first and / or second plurality of seals.
[0034] The flow control body may present any kind of shape or configuration as long as it comprises a blocking region with a first plurality of seals and a pass-through region with a second plurality of seals, the seals respectively engaging the sealing seats of the clamping unit in the close and open position of the flow control body. In embodiments, the flow control body may be a ball or present a plug configuration.
[0035] In use, i.e. after installation of the valve assembly, the rotation axis of the flow control body generally is either horizontal or vertical, as long as the seals are accessible to an operator for maintenance operation. In embodiments, after installation of the valve assembly (i.e. in use of the valve assembly), the rotation axis of the flow control body between the closed position of the valve assembly and the open position of the valve assembly is substantially vertical. While such a substantially vertical axis of rotation may complicate the installation / assembling of the valve assembly, in particular the installation of the flow control body inside the housing, or maintenance operation (including change) of the bearing unit, it allows for a more straightforward replacement of the seals and an easier maintenance of the clamping unit when the valve assembly is on site (i.e. in use / after installation). Indeed, the seals arranged onto the flow control body and the clamping devices are more easily accessible. The rotation axis being substantially vertical provides for an overall simpler maintenance, as the seals and sealing systems need a closer monitoring and should be replaced more often over the service time of a valve assembly than the bearing units.
[0036] In embodiments, the bearing unit is a segmented bearing unit comprising a first bearing unit and a second bearing unit, each bearing unit comprising a shaft portion and at least one bearing. Such a segmented bearing unit advantageously allows for a better separation and distribution of the axial and radial forces exerted by (and on) the flow control body, thereby increasing stability and solidity of the valve assembly.
[0037] Preferably, one of the bearing units is not connected to the housing. This advantageously allows for the path (i.e. flow passageway) of the flow control body to stay in line / aligned with the flow openings of the housing during use of the valveassembly, e.g. when the housing is dilatated due to high pressure and / or high temperature.
[0038] In preferred embodiments, and more preferably in embodiments wherein the rotation axis of the flow control body (i.e. flow control member) is vertical, the bearing unit comprises at least one spherical roller bearing and / or a thrust roller bearing, preferably two spherical roller bearings to take the radial forces and one thrust roller bearing to take the axial forces. Such a bearing unit is able to withstand the weight and mechanical forces of the flow control body while assuring a very precise and fast movement thereof. More preferably, in use of the valve assembly, the thrust roller bearing is arranged below (in the vertical direction) the flow control body so as to support it. The thrust roller bearing may advantageously take on most of the weight and mechanical forces of the flow control body while the spherical roller bearings ensure for a precise and accurate movement of the flow control body. However, in embodiments wherein the rotation axis of the flow control body is horizontal, the thrust roller bearing is not required and the bearing unit may not comprise a thrust roller bearing.
[0039] Preferably, the pass-through region of the flow control body is (internally) lined with refractory material, so as to further enhance thermal resistance of the valve assembly, and also protect the pass-through region (i.e. flow passageway) from corrosion and / or erosion due to the hot (reducing) gas flowing therethrough.
[0040] In embodiments, at least one portion of the shaft of the bearing unit is actively cooled, i.e. comprises an active cooling system. In embodiments comprising a segmented bearing unit with two shafts, at least a portion of each shaft is preferably actively cooled. In the present text, actively cooled means cooled by heat exchange with a flowing coolant, such as an inert gas or water. In preferred embodiments, the portion of the shaft is hollowed and a coolant (preferably water) flows therethrough, i.e. through the hollow portion of the shaft. The bearings themselves are thus preferably not directly cooled by the coolant, they are however effectively cooled by the coolant (preferably water) flowing through the shaft. Circulating a coolant through (at least a portion of) the shaft of the bearing unit enables to maintain a temperature below 120 °C, even below 100 °C or even below 80 °C in the proximity of the bearings.
[0041] Other parts of the valve assembly may also be actively cooled. In embodiments, the seals of the flow control body are arranged in respective seal carriers and at least one seal carrier comprises an active cooling system. Additionally or alternatively, the housing may comprise an active housing cooling system, such as e.g. by adding to the housing welded jackets in which a coolant is flowing, or by forming (e.g. by molding, drilling, ... ) coolant channels directly through the housing.
[0042] Active cooling allows to use mild steels for the various part of the valve assembly (bearing units, seals, housing...) thereby allowing the use of conventional materials and reducing production costs. Due to the active cooling, the (service) lifetime of the bearing units, seals and housing may be increased and the valve assembly may be used for regulating the flow of hotter gases.
[0043] According to preferred embodiments, the valve assembly further comprises a drive mechanism, such as e.g. an electrical drive mechanism, configured for actuating the bearing unit and / or configured for actuating the clamping unit.
[0044] A single electrical drive may be configured for actuating, and be used to actuate, all of the bearing unit and the clamping unit (i.e. both clamping devices). It is however also possible, and sometimes preferred, to use two distinct electrical drives, one configured for actuating the bearing unit and one configured for actuating the clamping unit. Electrical drive(s) advantageously simplify the control (and precise movement) of the bearing unit and clamping devices. Alternatively, an electrical drive may be configured for actuating, and used to actuate, the bearing unit while the clamping unit is actuated by hydraulic pistons.
[0045] Preferably, the drive mechanism receives commands and power from an electrical drive and transmits them to the receiving unit (clamping unit or bearing unit).
[0046] The drive mechanism may optionally comprise a gearbox for enhancing the precision and smoothness of the rotation of the flow control body and / or movement of the clamping devices of the clamping unit.
[0047] According to the same or other embodiments, the housing may be pressurisable and / or insulated. Such a housing advantageously further increases the safety of the valve assembly by preventing gas leakage. Indeed, as the housing is pressurisable, over-pressure inside the housing prevents leaking of any gas flowingthrough the valve assembly. In addition, or alternatively to being actively cooled, the housing being insulated further protects 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) induced by the two clamping devices of the clamping unit.
[0048] The housing may comprise removable cover(s) on one or more of its sides different from the first and second sides, preferably a top side or another lateral side. Such a removable cover may be used as entry port for inspection and / or maintenance (e.g. for maintenance of the pass-through region when the flow control body and thus the valve assembly is in the closed position), thereby facilitating maintenance operations.
[0049] The valve assembly 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. In preferred embodiments, the housing is over-pressurized (with respect to ambient environment) with nitrogen to prevent gas leakage inside the housing upon rotation of the flow control body. Added nitrogen creates an inert atmosphere inside the housing which prevents the build-up of explosive gas inside the valve housing. Alternatively or additionally, a gas purging system can be installed upstream or downstream of the valve assembly.
[0050] The shape and size of the gas path within the present valve assembly will generally adapt to the conducts in which it is intended to install the valve assembly. Hence, often the first and second openings of the valve housing will have a circular cross-section 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.
[0051] In embodiments, the first and second sides of the housing are opposite sides, thereby defining a linear i.e. straight path (or flow passageway) inside the housing. According to such embodiments, the path of the flow control body is linear i.e. straight. A flow control body with a linear pass-through region, i.e. a straight flow passageway is easier to manufacture (as it presents a simple, symmetrical design), manipulate and replace than a flow control body with another configuration for thepass-through region I flow passageway. Moreover, refractory lining can easily be manufactured and installed into a linear passageway.
[0052] As known to the skilled person, any uneven distribution of forces or temperature is detrimental to the lifespan of the valve assembly. To some extent, an even distribution can be achieved by a symmetric configuration of the components of the assembly. Thus, it is preferred that the openings, the sealing seats, the clamping devices, and / or the flow control body are symmetric about a common symmetry axis. It is understood that preferably all of the above-mentioned components are symmetric about the same symmetry axis, but it is also possible that only some of them have this kind of symmetry.
[0053] The present invention is particularly well suited for housings having a parallelepipedal shape, such as e.g. a cubic shape. Height, length and width of the housing may each vary between 1 m and 3 m. The valve assembly may have a weight comprised between 10 tons and 60 tons, and a main extension (e.g. diameter) of the flow member may range from 1.5 m to 2 m. 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.Brief Description of the Drawings
[0054] A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:Fig.1 is a perspective view of a valve assembly according to the present invention; Fig.2 is a perspective view of the housing;Fig.3 shows a) a perspective view and b) a A-A cross-sectional view of a ball unit; Fig.4 shows B-B cross-sectional views of a) the first bearing unit and b) the second bearing unit; andFig.5 is a detail A-A cross-sectional view of a sealing system.Description of Preferred Embodiments
[0055] Figs.1-5 show an embodiment of a valve assembly 10 according to the present invention, that can be connected to a gas injection system of a furnace. The valve assembly 10 comprises a valve housing 12 (or simply housing, sometimes alsoreferred to as valve casing), which can be made of one or several pieces of steel, a valve insert comprising a flow control body 20 arranged inside the valve housing 12 for varying the free passage therein, a bearing unit 40 and a clamping unit 60.
[0056] The housing 12 may present any shape, however parallelepipedal shapes with a top side 12.1 , a bottom side 12.2 and four lateral sides 12.3, 12.4, 12.5, 12.6 are preferred. The valve housing has a first flow opening 14 arranged in a first lateral side 12.3, and a second flow opening (not shown) arranged in a second lateral side 12.4. As apparent from Fig.1 , in embodiments the first and second sides 12.3, 12.4 are opposite lateral sides, so that the first 14 and second flow openings are aligned along a central axis A-A, and an open passageway is defined from one side of the housing 12.3 to the other side 12.4 through the first flow opening 14, the interior of the housing 12 and the second flow opening. In other words, the first and second openings communicate through the interior of the valve housing.
[0057] The openings 14 may be arranged on right and left sides 12.3, 12.4 of the housing, it is however just an embodiment for illustration purpose and the openings may be arranged e.g. on front and back sides 12.5, 12.5 of the housing. Moreover, in the present description, all adjectives relative to a spatial arrangement such as upper, lower, right, left, front, back, top, bottom, above, below referred to a position relative to the valve assembly in use, i.e. once installed.
[0058] A maintenance opening 16 is arranged on a third lateral side 12.5 1of the valve housing (Fig.2) to provide access to the inside of the 2 housing and to the elements arranged therein, e.g. the flow control body 20. The top side 12.1 may comprise a removable cover 8 and / or an inspection port (or through-hole), which may also be regarded as a further maintenance opening (Fig.2). During operation of the valve assembly, the maintenance opening 16 is sealingly closed by a maintenance door 16.2.
[0059] The maintenance opening 16 and removable cover 18, and to a lesser extend the inspection port, allow for easier precautionary inspections of any part of the valve assembly 10 (in particular the seals of the flow control body), which enables to detect any possible problems at an early stage, and without requiring dismantling of the valve assembly 10 from the gas injection system. Therefore, any shutdown time of the gas injection system- or at least part of it - can be minimized.
[0060] The valve housing may further comprise one or more gas purging ports / systems and / or condensate drainage ports (not shown). While the gas purging ports may be placed in a number of locations of the housing for purging the valve housing, condensate drainage ports are located at a lowermost point in the valve housing or at different locations where condensate may accumulate. Prior to any maintenance operation, the valve housing and the duct line to which it is connected (not shown) are purged with nitrogen to ensure the safety of the maintenance operators.
[0061] The flow control body 20 (Fig.3) has an envelope with rotational symmetry about a rotation axis, and comprises a blocking region 22 for blocking a path between the flow openings 14, and a pass-through region 32 for opening said path. The pass-through region 32 preferably presents a cross-section substantially identical to that of the flow openings 14 of the valve housing. In the presently disclosed embodiment, the flow control body 20 is shaped as a ball, however it may present any shape or configuration being rotatable and presenting both a blocking region 22 and a pass-through region 32, such as e.g. a plug configuration.
[0062] In the pass-through region 32, the flow control body has an inner passageway, or flow passageway 38, extending between two extremities 36.1, 36.2, for allowing the passage of gases therethrough. The blocking region 22 presents plain sections 26 preventing passage of gases.
[0063] The flow control body 20 is rotatably disposed within the valve housing 12 and is rotatable (around a rotation axis) between an open position and a closed position.
[0064] In the open position of the flow control body 20 (i.e. open position of the valve assembly 10), the pass-through region 32 is aligned with the first and second openings 14, of the housing 12 and thus opens a path therebetween. A (hot, pressurized, reducing) gas flows from the first opening 14 toward the second opening of the housing via the flow passageway 38 of the pass-through region 32 of the flow control body 20.
[0065] In the closed position of the valve assembly 10 (i.e. of the flow control body 20), the blocking region 22 1 is aligned with the first 14 and second openings, of the housing 12, thereby closing the path therebetween. The pass-through region 32 isadvantageously aligned with the maintenance opening 16 on the further lateral side 12.5 of the housing, allowing for an easy to implement inspection thereof. In other words, in the closed position of the flow control body 20, the extremities 36.1 , 36.2 of the flow passageway 38 are not aligned with the flow openings 14 of the valve housing 12.
[0066] Seals 24, 34 are arranged at the extremities of both the blocking region 22 and pass-through region 34. A first plurality of seals 24, received in respective seal carriers, are arranged on the blocking region 22 (preferably on the plain sections 26) and are disposed and configured for ensuring a gas-tight, leak-free closure of the valve assembly in the closed position. A second plurality of seals 34, received in respective seal carriers, are arranged on the pass-through region 32, namely at the extremities 36.1 , 36.2 of the passing region (i.e. at the extremities of the flow passageway 38) and are disposed and configured for ensuring a gas-tight, leak-free passage of gases through the valve assembly via the flow control body.
[0067] The seals 24, 34 may be of any kind known in the art to work for valve assembly regulating the flow of gases having a temperature up to 1500 °C, up to 1600 °C or even up to 2000 °C. Suitable seals may be plain parts with cone to sphere contact or metallic C-rings against a conical surface. While it is desired that the seals may work at a temperature above 1300 °C, preferably above 1400 °C and more preferably above 1600 °C, the seating surface of the seal is not expected to exceed 800 C, due to water-cooling thereof, so that a wider variety of seals may be used. The material of the seals has to be suitable for H2 services at elevated temperature.
[0068] Seals of the first and second plurality of seals may be different from each other, it is however preferred that all seals 24, 34 arranged on the flow control body 20 be of similar construction or identical.
[0069] The seal carriers of the first or second, preferably first and second, plurality of seals 24, 34 comprise hollow channels (not shown) for flowing a coolant therethrough, such as water, thereby actively cooling the seals of the flow control body.
[0070] The flow control body (here in a ball configuration) may further comprise hollow channels (not shown) for flowing a coolant therethrough, such as water, thereby actively cooling the flow control body and improving its resistance to heat.
[0071] Additionally or alternatively, the pass-through region of the flow control body may be internally lined with refractory material (not shown), to further increase its resistance to the high to very high temperature of the gas flowing therethrough.
[0072] In addition to the flow control body 20, the valve insert further comprises a bearing unit 40 (Fig.4). The bearing unit comprises three bearings 42, 44, 46 and a shaft 48 rotatable around a rotation axis B-B of the bearing unit, which is the rotation axis B-B of the flow control body 20. The bearing unit 40 is configured for supporting and moving i.e. rotating the flow control body 20 of the valve assembly 10, i.e. the flow control body 20 is rotatable between its open and closed position by actuation on I rotation of the shaft 48 of the bearing unit 40.
[0073] In other words, rotation axis of the flow control body 20 is determined by the extension direction of the shaft 48 of the bearing unit 40, along a vertical axis B-B.
[0074] The bearing unit 40 may be regarded as being a segmented bearing unit comprising a first bearing unit 40.1 (Fig.4a) and a second bearing unit 40.2 (Fig.4b). The first bearing unit 40.1 has a hollow shaft portion 48.1 and a spherical roller bearing 42 while the second bearing unit 40.2 has a hollow shaft portion 48.2, a spherical roller bearing 44 and a thrust roller bearing 464. The first bearing unit 40.1 2connects an upper side of the flow control body 20 while the second bearing unit 40.2 connects a lower side of the flow control body 20. Rotation of the flow control body occurs upon actuation, i.e. rotation, of the shaft portion 48.1 of the first bearing unit 40.1.
[0075] As apparent from Fig.1 , the shaft portion 48.1 of the first bearing unit 40.1 is arranged through a (further) hole of the top side 12.1 of the housing 12, such as e.g. a hole provided in a removable cover 18 of the housing.
[0076] Preferably, the second bearing unit 40.2 is decoupled from the housing 12, in particular from the bottom side 12.2 of the housing, and further comprises an axial support 50. The axial support 50 is also decoupled from the bottom side 12.2 1of the housing 12 and ensures that the second bearing unit stays in position when the valve assembly 10 is in use, in particular if the housing is dilatated (because of thermal expansion) due to the very hot gas flowing through the valve assembly.
[0077] As apparent from Fig.1 , a clamping device 62, 64 is arranged at each flow opening 14, of the housing 12, to provide connection with further elements (notshown) of a gas injection system while ensuring a gas-tight, leak-free sealing with the flow control body 20 of the valve insert.
[0078] The clamping unit 60 comprises the two clamping devices 62, 64 (only one being represented on Fig.5). A first clamping device 62 is sealingly arranged at the first flow opening 14 of the gas-tight valve housing 12 and a second clamping device 64 is sealingly arranged at the second flow opening (Fig.1 ). The two clamping devices 62, 64 are of similar construction, and only one clamping device will be further described in details.
[0079] A clamping device 62 comprises a body 66 (generally made of steel but other materials may be used) with a sealing seat 68 arranged and configured for engaging either a seal of the first plurality of seals 24 of the flow control body or a seal of the second plurality of seals 34. When the flow control body 20 is designed as a ball, the sealing seat 68 may be designed as a cone-to-sphere contact so as to fit I adapt to the geometry of the seal arranged on the flow control body 20. Preferably, the sealing seat 68 is made integral with the body 66 of the clamping device 62.
[0080] In a clamped position (Fig.5), the sealing seat 68 sealingly engages a seal 34 of the flow control body 20 and the device is in a rest position, or inactive configuration, namely the clamping device 62 does not need any power (electrical, mechanical or otherwise) to stay in this position.
[0081] The clamping device 62 is movable from the clamped position toward an unclamped position during rotation of the flow control body 20 by an actuating mechanism. In the unclamped position (not shown), the sealing seat 68 of the clamping device 62 is further away from the flow control body 20 than in the clamped position so that a gap occurs between the sealing seat and the seal(s) of the flow control body.
[0082] The actuating mechanism may be of any kind, however in the presently disclosed embodiment it is a hydraulic actuating mechanism comprising a plurality of hydraulic pistons 70 uniformly arranged on a periphery of the clamping device 62. That is to say, the pistons are evenly distributed over the whole contact line between the body of the clamping device and the valve housing. The number and type of pistons 70 depends on the dimensions of the clamping device and thus on the dimensions of the valve assembly, but preferably at least six pistons, each having a seat loadbetween 100 N / mm and 1000 N / mm, are provided over the circumference (or periphery) of the body of the clamping device.
[0083] All pistons (or actuators) can be operated by increasing or decreasing the hydraulic pressure in a single distribution system. For instance, the actuator may comprise a cylinder in which a plunger is disposed. A part of the cylinder on one side of the plunger may be connected to an inlet for hydraulic fluid, while a spring element is disposed in the other side of the plunger. If the hydraulic pressure is reduced, the spring element moves the plunger in one direction, while an increasing hydraulic pressure moves the plunger in the opposite direction.
[0084] The clamping device 62 may further comprise a metal bellow 72, or bellow seal, arranged between the body of the clamping device and the valve housing, allowing to hermetically close the clamping devices, thereby permitting the placement of the clamping actuators outside the valve housing 12.
[0085] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiment.
[0086] List of reference numbers10 Valve assembly 36.1 / 36.2 Extremity of the pass-through region12 Housing 38 Flow passageway12.1 Top side 40 Bearing unit12.2 Bottom side 40.1 First bearing unit12.3 First lateral side 40.2 Second bearing unit 12.4 Second lateral side 42, 44 Spherical roller bearing 12.5 Third lateral side 46 Thrust roller bearing 12.6 Fourth lateral side 48 Shaft14 First flow opening 48.1 First shaft portion16 Maintenance opening 48.2 Second shaft portion 16.2 Maintenance door 50 Axial support18 Removable cover 60 Clamping unit20 Flow control body 62, 64 Clamping device22 Blocking region 66 Body of clamping device 24 Seal (of the first plurality) 68 Sealing seat26 Plain section 70 Hydraulic piston32 Pass-through region 72 Metal bellow34 Seal (of the second plurality) A-A Central axisB-B Rotation axis
Claims
Claims1. A valve assembly for an industrial plant, comprising:- a gas-tight housing with a first flow opening arranged in a first lateral side thereof and a second flow opening arranged in a second lateral side thereof;- a clamping unit comprising a first clamping device with a first sealing seat and a second clamping device with a second sealing seat, the clamping devices being respectively arranged at the first and second flow openings; and- a valve insert arranged within said housing between said first and second flow openings,wherein said valve insert comprises:- a bearing unit comprising at least two bearings and a shaft rotatable around a rotation axis of the bearing unit;- a flow control body comprising a blocking region for blocking a path between the flow openings and a pass-through region for opening said path; the flow control body being rotatable around the rotation axis of the bearing unit between a closed position wherein the blocking region is in alignment with the flow openings and an open position wherein the pass- through region is in alignment with the flow openings;- the flow control body further comprising first and second plurality of seals, respectively disposed on the blocking region and the pass- through region, the seals of the first plurality being arranged to sealingly engage the first and second sealing seats of the clamping unit in the closed position of the flow control body and the seals of the second plurality being arranged to sealingly engage the first and second sealing seats of the clamping unit in the open position of the flow control body; wherein each clamping device is movable between a clamped position in both the open and closed position of the flow control body, the clamped position being a rest position sealingly engaging the sealing seats of the clamping devices and the first or second seals of the flow control body, and an unclamped position being an active position during rotation of the flow control body.
2. The valve assembly as claimed in claim 1, wherein each clamping device comprises a metal bellow.
3. The valve assembly as claimed in claim 1 or 2, wherein each clamping device is moved from the clamped position to the unclamped position by means of an actuating mechanism.
4. The valve assembly as claimed in claim 3, wherein the actuating mechanism is selected from a hydraulic, pneumatic or electric mechanism, or a combination thereof.
5. The valve assembly as claimed in claim 4, wherein the actuating mechanism is a hydraulic mechanism comprising a plurality of parallel-acting hydraulic pistons, more preferably at least six hydraulic pistons, each having a seat load between 100 N / mm and 1000 N / mm.
6. The valve assembly as claimed in any one of the preceding claims, wherein the two clamping devices are simultaneously moved from one clamped / unclamped position to the other unclamped / clamped position.
7. The valve assembly as claimed in any one of the preceding claims, wherein the flow control body is a ball or a plug configuration.
8. The valve assembly as claimed in any one of the preceding claims, wherein, after installation, the rotation axis of the flow control body between the closed position and the open position is substantially vertical.
9. The valve assembly as claimed in any one of the preceding claims, wherein the bearing unit comprises at least one spherical roller bearing and / or a thrust roller bearing, preferably two spherical roller bearings and one thrust roller bearing.
10. The valve assembly as claimed in any one of the preceding claims, wherein the pass-through region of the flow control body is lined with refractory material.
11. The valve assembly as claimed in any one of the preceding claims, wherein at least one portion of the shaft of the bearing unit comprises an active cooling system.
12. The valve assembly as claimed in any one of the preceding claims, wherein the seals of the flow control body are arranged in respective seal carriers and wherein at least one seal carrier comprises an active cooling system.
13. The valve assembly as claimed in any one of the preceding claims, wherein the housing comprises an active housing cooling system.
14. The valve assembly as claimed in any one of the preceding claims further comprising a drive mechanism, preferably an electrical drive mechanism, configured for actuating the actuating mechanism of the clamping unit and / or configured for actuating the bearing unit.
15. The valve assembly as claimed in any one of the preceding claims, wherein the housing is pressurisable and / or insulated.
16. The valve assembly as claimed in any one of the preceding claims, wherein the housing comprises removable cover(s) on one or more of its sides different from said first and second sides, preferably a top side or another lateral side.
17. The valve assembly as claimed in any one of the preceding claims, wherein the first and second sides of the housing are opposite sides and the path is linear.