GB2516044A

GB2516044A - Valve

Info

Publication number: GB2516044A
Application number: GB1312269.2A
Authority: GB
Inventors: Barry Wilder
Original assignee: SEV GLOCON Ltd
Current assignee: SEV GLOCON Ltd
Priority date: 2013-07-09
Filing date: 2013-07-09
Publication date: 2015-01-14
Anticipated expiration: 2033-07-09
Also published as: GB2516044B; GB201312269D0

Abstract

A high energy flow control device comprises a valve 10 and a stack of plates. The plates define a series of fluid paths between an inner and outer circumference of the plates. The plates are provided as pairs comprising a first and a second plate. Each of the first and second plates of a pair comprises one or more linear arrays of circumferentially spaced apart apertures, which apertures define sections of a fluid path leading through the first and second plates of the pair. The sections are radially spaced apart by flat portions. Within a stack, the pairs are radially offset such that the sections of the first pair are covered by the flats of the second pair and vice versa. The flats keep the fluid path of the first pair separate from the fluid path of the second pair.

Description

This invention relates to high energy flow control devices. More specifically, the invention relates to high energy pressure control valves for effecting energy dissipation in high energy flows of liquids and gases.

It is known to control high energy fluid flows, for example the gas output from a gas compressor, by passing the fluid through a high energy pressure control valve incorporating a stack of annular plates defining a series of generally radially extending tortuous passageways for the fluid which impart repeated changes of direction to the fluid and which thereby serve to dissipate a proportion of the fluid energy. It is also known for such a pressure control valve to be adjustable in dependence on the sensed pressure of the fluid external to the valve in order to vary the number of passageways available for fluid flow through the valve so as to control the pressure or flow of the fluid downstream of the valve within an acceptable range.

Such high energy pressure control valves are used to reduce the fluid pressure to manageable levels and to thereby avoid a number of problems which may otherwise be experienced in applications in which high energy fluid flows are present. Such problems include vibration and noise, erosion and cavitation which can lead to greatly reduced life of the component parts associated with the fluid flow, as well as leading to unpredictable fluid flow behaviour.

GB2335054B, owned by the Applicant of the present invention, discloses a high energy flow control device comprising a plurality of coaxial annular plates joined together into a rigid stack to define a series of energy loss paths for fluid flow. The plates comprise first, second and third plates. The first plates are blanking plates to separate the energy loss paths defined between each adjacent pair of first plates from the energy loss paths between other adjacent pairs of first plates. There is at least one second plate and at least one third plate between each adjacent pair of first plates. The second and third plates each have a plurality of apertures therein. The apertures in the second and third plates communicate with one another to define a series ot fluid flow passageways extending from the inner circumference to the outer circumference of the plate. Each aperture in one of the second and third plates overlaps two spaced apart apertures of the other of the second and third plates in order to permit interaction between adjacent fluid flow passageways.

The arrangement outlined hereinbefore requires blanking plates to be provided in the stack in order to separate individual pathways within an assembly. The blanking plates increase the stack height, weight, and pioduction cost. The present invention seeks to address one ci more of these problems.

According to a first aspect of the present invention, there is provided a high energy flow control device comprising a plurality of plates having a first edge and a second edge, the plates being joined to foim a stack defining a seiies of energy loss paths connecting the first and second edges for fluid flow, the plates comprising pairs formed of adjacent plates, there being at least one first pair and at least one second pair, each pair comprising a fiist plate and a second plate, each of the first and second plates of each pair comprising one or more arrays of spaced apart apertures, the apertures defining sections of a fluid path which leads through the first and second plates and connects the first and second edges thereof with one another, the sections of the fiist plates being offset ielative to the sections of the second plates such that each section of the first plate partially overlaps with adjoining sections of the second plate to form the fluid path, and the one or more linear arrays of each plate being spaced apart by flat poitions extending from the fiist edge to the second edge, wherein the sections of one of the fiist and second pair align with the flat portions of the other of the first and second pair thereby keeping the fluid path of the first pair separate from the fluid path of the second pair.

It is an advantage of the present invention that a fluid path through a pair of plates can be separated from adjacent plates by virtue of the spatial arrangement of the apertures, i.e. without the need for intermediate blanking plates between the fluid paths of a pair.

In other words, only a top and a bottom blanking means may be required in a valve stack, and the blanking function of these blanking means may be provided by seal members or the like in a valve assembly, such that not even top and base blanking plates may be required. Because there is no requirement for intermediate blanking plates to close each flow path, a more compact valve stack can be achieved.

In one embodiment, the first plates of the first and second pairs are identically shaped.

In one embodiment, the second plates of the first and second pairs are identically shaped.

Using plates having identical shape is an advantage. Fewer plate designs mean that less manufacturing equipment is required. Thus, throughput per plate is higher overall production cost of a flow control device is lower. Further, logistics are simpler for a product consisting of fewer component designs.

In one embodiment, the plates of the first pair in the stack are facing up and the plates of the second pair in the stack are facing down.

It is an advantage that the plates of one pair can be arranged to face in one direction and the plates of the other pair can be arranged to face into the other direction.

Thereby, only two different plate designs are required in a trim stack. Nevertheless, the present invention allows an arrangement to be provided in which the paths of the first and second pairs do not overlap, while using identically shaped first plates and identically shaped second plates.

In one embodiment, the first and second pairs are alternated in the stack.

It is an advantage that alternating pairs are used in the stack because the assembly of the stack and the quality control during production are facilitated.

One or both plates of a pair may comprise one or more slots in addition to the apertures defining the sections.

The additional slots provide the advantage that, when plates are brazed together, excess filler material can collect in the slots which avoids undesirable accumulation of filler material in the flow path apertures. Further, the slots allow reduction of the weight of the plates and the amount of material required for production of the individual plates.

One or both of the inner circumference and the outer circumference of the plates may be circular, hexagonal, or octagonal.

A regular geometric shape of the outer circumference is advantageous to improve alignment within a valve assembly. A regular geometric shape of the inner circumference is advantageous for cooperation with an openable valve seal.

The plates may be marked on one side. A marker identifying the top side or base side of a plate can be advantageous during production. This is because the plates need to be provided in a stack in the correct alternating order to work optimally.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an axial section through a valve comprising a plate trimmer stack in accordance with an embodiment of the invention; Figure 2 is a partial view of a section through a plate trimmer stack (with some elements omitted for clarity); Figure 3 is a plan view of a first plate of a pair of plates (with some elements omitted for clarity); Figure 4 is a plan view of a second plate of a pair of plates (with some elements omitted for clarity); Figure 5 is a wireframe view of superimposed and aligned first and second plates (with some elements omitted for clarity); Figure 6 is a wireframe view of superimposed and aligned first and second pairs (with some elements omitted for clarity); and Figure 7 is a radial section along the line A-A of Figure 6 through a trim stack consisting of five pairs.

Figure 1 shows a control valve 10 used in conjunction with a trim stack in accordance with an embodiment of the present invention. Control valve 10 comprises a housing 11 having an inlet port 14 and an outlet port 16, each of which can be connected to a pipe.

The direction of flow may run from the inlet port 14 to the outlet port 16, as indicated by arrows in Figure 1. Alternatively, the flow may be directed from port 16 to port 14. The housing 11 is configured to accommodate a trim stack 18 in the fluid path between the pods 14 and 16. Trim stack 18 is mounted in the housing 11 between a valve seat 28 and a top plate 29. The trim stack 18 comprises an inner space 25 through which a valve plug 20 extends. With trim stack 18 in place, fluid communication between the inlet port 14 and outlet port 16 is only possible through fluid passages provided in the trim stack 18. These fluid passages extend through the thickness of trim stack 18 between the inner space 25 and the outer circumference of trim stack 18.

Valve 10 further comprises a cover 12 which clamps the trim stack in its position in the housing 11. The cover 12 supports the valve plug 20 for movement, the valve plug 20 extending through an inner seal 22 and a cover bore 23. An end portion 24 of the valve plug 20 extends into the valve housing 11 and is located within the inner space of the trim stack 18, closing the inner ends of the fluid passages. The valve plug 20 is inwardly or outwardly displaceable in the cover 12 as indicated by arrow 26, whereby the end part 24 can be retracted from the inner space 25 to open the valve, or inserted to engage the seat 28 and fully close the valve. When valve plug 24 is fully inserted into the trim stack 18 to engage with the valve seat 28, any fluid passage between inlet port 14 and outlet port 16 is blocked. The valve plug can be partially inserted into, or retracted from, the inner space 25 thus only blocking, or opening, a proportion of the fluid paths of the trim stack 18.

As shown in the partial cross-section of Figure 2, trim stack 18 is comprised of a stack of plates having an inner circumference and an outer circumference. The plates are brazed together to form a single annular body. The inner circumference of the plates defines the inner space 25. In one embodiment, the plates are circular. Other shapes, such as a hexagonal or octagonal circumference, are contemplated. The plates comprise apertures which define sections of fluid passages between the inner and outer circumference of the trim stack 18.

Figures 3 and 4 show two trimmer plates 30 and 31 which can be superimposed to form a pair such that the apertures of either plate overlap in a complementary manner to form fluid passages between the inner and outer circumference of the pair. The superposition of two complementary plates 30 and 31 is illustrated in a wireframe view in Figure 5.

Plate 30 as shown in Figure 3 may be understood as the first plate of a pair and plate 31 as shown in Figure 4 may be the second plate of a pair. Each plate 30 and 31 is generally annular and has an inner diameter configured to receive the end portion 24 of the valve plug 20 and an outer diameter which is accommodated in the valve housing 11. The inner diameter of first plate 30 is smaller than the inner diameter of second plate 31, allowing a close fit of the end portion 24 within the inner diameter of the first plate 30. Consequently, end portion 24 will not fit closely in the larger inner diameter of second plate 31. Thereby, a pressurised fluid may spread evenly around the end portion 24 as a valve plug is retracted from the trim stack. This is advantageous because any inflowing fluid may flow evenly around the end portion 24 and thus the entry pressure is distributed among the fluid passage entry slots within a pair. Further, the rim formed by the inner circumference of the first plate 30 allows a step-wise control of the valve because the end portion does not have to be aligned exactly between plates. However, embodiments may be provided in which both plates 30 and 31 may have the same inner diameter.

Each of the plates 30 and 31 has a plurality of apertures which are arranged in a plurality of linear arrays 32 and 33. The first plate 30 may comprise, for example, twelve linear arrays 32 and the second plate 31 may comprise, for example, twelve linear arrays 33. In Figures 3 and 4, only one complete array 32 and one complete array 33 are illustrated, the others being omitted (for the most part) for clarity. Each linear array 32, 33 extends radially between the inner circumference and the outer circumference of the respective plate 30, 31. Each linear array 32, 33, in this embodiment, comprises seven apertures which are circumferentially spaced apart by strut portions of the plate. Each linear array 32 of first plate 30 of Figure 3 is radially aligned with the corresponding linear array 33 of the second plate 31 of Figure 4.

In Figure 3, the outer-most apertures 38 of each linear 32 array open up to the outer circumference of the first plate 30. Likewise, the inner-most apertures 39 of each linear array 33 open up to the inner circumference of the second plate 31 in Figure 4.

Because the apertures within each array 32, 33 are circumferentially spaced apart by the strut portions, no fluid communication is possible between the inner-most aperture and the outer-most aperture within one plate. The strut portions may be straight, i.e. tangential to the plates, or may be arcuately shaped, in which case the inner and outer edges of the strut portions may be concentric with the inner circumference or with the outer circumference. Consequently, the inner and outer edges of the apertures may be straight or arcuately shaped, as defined by the shape of the strut portions.

Because the apertures of the first plate 30 of Figure 3 are circumferentially offset relative to the second plate 31 of Figure 4, yet radially aligned with the second plate 31, the apertures of the first plate come to lie on the strut portions of the second plate when the two plates 30 and 31 are superimposed to form a pair. In particular, the strut portions are shorter than the apertures. Thus, when a first plate 30 is aligned and joined with a second plate 31 to form a pair, even though the apertures cover the struts, each aperture overlaps with the next inner and the next outer aperture of the other plate of the pair. The outer-most apertures 38 of the first plate 30 overlap only with the outer-most aperture of the second plate 31 and can thus be regarded as exit slots 38 of a pathway. Likewise, the inner-most apertures 39 of the second plate 31 overlap only with the inner-most apertures of the first plate 30 and can thus be regarded as entry slots 39 of a pathway. When the flow within the valve 10 is directed from port 16 to port 14, the outer-most apertures 38 will be entry slots and the inner-most apertures 39 will be exit slots.

Each plate 30 and 31 is provided with three cut-outs 40, 41, 42, which are equidistantly spaced apart, e.g. at an orientation of 0°, 120° and 240°. These cut-outs facilitate radial alignment of the superimposed plates during production of a trim stack. Figure 5 shows the alignment of the three cut-outs 40, 41, and 42. Other cut-out configurations may be provided but it is desirable that the configuration has reflection symmetry along an axis through the 0° cut-out 40, for reasons set forth below.

The width of each aperture increases gradually within a linear array 32, 33 from the inner circumference to the outer circumference, such that the radial, or lateral, edges of the apertures within a linear array 32, 33 are generally bordering on two radial lines of a plate. Some deviation from a straight radial line may occur as a design choice. For instance, as shown in Figures 3 and 4, the width of the apertures increases in progressively incrementing steps towards the outer circumference such that the lateral edges of each linear array 32, 33 are convex with respect to each other, thereby achieving a hyperbolic outline of the linear arrays 32, 33. Each array 32, 33 has a generally slender radial extent. This has the advantage that support webs are not required within an aperture and allows accommodation of a larger number than usually employed of fluid passages in a plate. For instance, the plates shown in Figures 3 and 4 comprise twelve linear arrays 32, 33, whereas prior art systems may have used plates having six arrays.

Each aperture has approximately the same length between the inner and outer circumference of a plate. Likewise, the thickness of the strut portions between each aperture of an array is approximately the same. This facilitates the design of fluid path at the design stage. A progressively increasing width results in a progressively increasing cross-section of each aperture within an array, which improves the flow pressure reduction towards the outer circumference. Embodiments which are intended for a flow direction from the outer to the inner circumference may have a reverse design. E.g., the length or the width of the apertures may increase towards the inner circumference.

The linear arrays 32, 33 are radially spaced apart from each other by flats 34, 35. At any given circumferential position, the flats 34, 35 are wider than the apertures. Like the array of apertures 32 and 33, the flats 34 and 35 are gradually widening towards the outer circumference of the plate. Because the arrays of apertures have a hyperbolic lateral outline, the width of the flats 34, 35 increases in progressively decreasing steps towards the outer circumference. Towards the outer circumference, the lateral edge portions of the flats 35 of the second plate 35 are almost parallel.

In addition to the linear arrays of apertures 32, plate 30 of Figure 3 comprises terete or elongate slots 36 that extend partway along each linear array within the flats 34. These elongate slots 36 are not in fluid communication with any of the apertures. When aligned with the second plate 31, each elongate slot 36 comes to lie on a flat 35 of the second plate 31 alongside, and spaced apart from, a corresponding linear array of apertures 33. Thus, no fluid path is opened through the elongate slot 36 by superposition of a first plate 30 and a second plate 31.

The advantage of the elongate slots 36 is that they can collect excess filler material used for brazing the plates together during manufacture of a trimmer plate stack. Not having to carefully limit the amount of filler material during production of a stack reduces the risk of bleeding as a result of undesired paths remaining between plates.

This allows a tighter stack to be formed while facilitating the brazing process. Another advantage is that less material is required for the production of individual plate. This reduces the plate weight and production cost.

The fluid path formed by the complementary arrays of apertures 32, 33 within a pair of plates 30 and 31 must be closed off. Hitherto, the exposed upper and lower sides of the apertures of a stack had to be closed by blanking plates.

According to the present invention, separate blanking plates are not required because the blanking function is provided by flat portions 34, 35 of adjacent pairs of plates. This can be achieved because the arrays of apertures 32, 33 are less wide than the flats 34, between the apertures. For instance, the first and second plates of a second pair may comprise a substantially identical arrangement of apertures which arrangement is rotationally offset such that the arrays of apertures align with the flats of the first pair.

The provision of a slender array of apertures and wide flat portions increases the design freedom for the plates. A trimmer plate stack will thus consist of at least two alternating pairs of trimmer plates, each pair of plates requiring a first and second plate.

In an embodiment, the apertures are arranged on the first and second plate in such a manner that only two different plate types are required to form either a first pair or a second pair in a stack, while still allowing a plate stack without dedicated blanking plates to be formed. In other words, a stack is formed of only two plate designs, which two designs are the first plates 30 and the second plates 31. Having to produce only two different plate types reduces production and storage cost. The blanking function of the flat portions is achieved by alternating upward-facing and downward-facing pairs, i.e. by flipping the plates of a pair.

The first and second plates 30 and 31 described above are suitable for an alternating a configuration. Figure 6 shows an isometric wireframe view of a stack 18 consisting of two alternating types of pairs, each pair consisting of one first plate 30 and one second plate 31, wherein each first pair of plates 30 and 31 is oriented exactly as shown in Figure 5, and each second pair of plates 30 and 31 is superimposed in essentially the same orientation, but turned over and aligned with the first pair. The aligned cut-outs 40, 41, 42 illustrate the alignment. As mentioned earlier, the cut-out configuration should exhibit reflection symmetry to allow alignment of the upward-facing pairs with the downward-facing pairs.

In Figure 6, the linear arrays of apertures of the first pair are covered by the flat portions of the second pair, and vice versa. This is possible because the flats 34, 35 are wider than the corresponding apertures, and because the linear arrays 32, 33 come to lie between the flats 34 or 35 when the plates 30 and 31 face the other way with respect to each other. Thereby! the blanking function can be provided without the provision of additional blanking plates. Again, in Figure 6, only some of the arrays 32, 33 are illustrated, the remainder being omitted from the drawings for clarity.

In a trim stack 18, two plates 30 and 31 are provided as a first pair whose apertures are closed off by the plates lying above and below the first pair. Those plates lying above and below can be part of another pair of plates, which consists of the same plates 30 and 31 but which plates are facing down rather than up. The apertures of the top and base plate of a stack are closed by valve seal members 28 and 29. Where such valve seal members are not suitable for closing the arrays of apertures, a trimmer stack may comprise a top blanking plate and a base blanking plate.

Figure 7 shows a radial section along the line A-A of Figure 6. For simplicity, a stack 18 consisting of five pairs is depicted in Figure 7. Each of the five pairs in Figure 7 consists of a first plate 30 and a second plate 31. The first, third, and fifth pairs are facing up, and the second and fourth pairs are facing down. The section of Figure 7 cuts through the flats 34 and 35 of the up-ward-facing pairs. Sandwiched between the flat portions of the odd-numbered pairs are the linear arrays 32 and 33 of the even-numbered pairs in the stack. I.e., the flat 34 of the first plate 30 of the first pair covers the exposed side of the array 33 of the second plate 31 of the second pair. On the other side of the second pair, the flat 35 of the second plate 31 of the third pair covers the exposed side of the array 34 of the first plate of the second pair.

Fluid pressurised against the inside of the trim stack 18 can only flow through open entry slots 39 from where it flows straight for a short distance until it abuts against the first strut portion of the second plate 31. The path then requires the flow to change direction axially, either up or down depending on the plate arrangement, into the inner end of the inner-most aperture of first plate 30. The path then leads outwards over the first strut portion of the second plate 31 towards the outer end of the inner-most aperture. The outer-most end of the inner-most aperture of the first plate 30 overlaps with the inner end of the next aperture of the second plate 31. The overlap allows liquid to enter axially and continue following the path in this manner through the apertures until it reaches the exit slot 38. The repeat change of direction results in a loss of energy which is correlated with the number of apertures in an array.

By way of the aperture design and alternating pair configuration, a high number of fluid passages per plate can be achieved while allowing the stack height to be reduced.

Claims

CLAIMS: 1. A high energy flow control device comprising a plurality of plates having a first edge and a second edge, the plates being joined to form a stack defining a series of energy loss paths connecting the first and second edges for fluid flow; the plates comprising pairs formed of adjacent plates, there being at least one first pair and at least one second pair; each pair comprising a first plate and a second plate; each of the first and second plates of each pair comprising one or more linear arrays of circumferentially spaced apart apertures, the apertures defining sections of a fluid path which leads through the first and second plates and connects the first and second edges thereof with one another; the sections of the first plates being circumferentially offset relative to the sections of the second plates such that each section of the first plate partially overlaps with adjoining sections of the second plate to form the fluid path; and the one or more linear arrays of each plate being radially spaced apart by flat portions extending from the first edge to the second edge; wherein the sections of one of the first and second pair align with the flat portions of the other of the first and second pair thereby keeping the fluid path of the first pair separate from the fluid path of the second pair.
2. The high energy flow control device according to claim 1, wherein the first plates of the first and second pairs are identically shaped; and/or wherein the second plates of the first and second pairs are identically shaped.
3. The high energy flow control device according to claim 1 or2, wherein the plates of the first pair in the stack are facing up and the plates of the second pair in the stack are facing down.
4. The high energy flow control device according to any one of the preceding claims, wherein the first and second pairs alternate in the stack.
5. The high energy flow control device according to any one of the preceding claims, wherein one or both of the first and second plates comprise one or more slots in addition to the apertures defining the sections.
6. The high energy flow control device according to any of the preceding claims, wherein the plates are of annular form, the first edge forming an inner circumference and the second edge forming an outer circumference thereof.
7. The high energy flow control device according to claim 6, wherein one or both of the inner circumference and the outer circumference of the plates is circular, hexagonal, or octagonal.