MXPA99007167A - Fluid pressure reduction device - Google Patents

Abstract

A fluid pressure reduction device with low noise generation. A stack of annular disks (30a, b, c, d) with fluid passageways formed of inlet slots (36), outlet slots (38), and interconnecting plenums (40). Selectively stacking and orienting the annular disks along with an asymmetric slot pattern creates the desired fluid passageways without creating an uninterrupted axial fluid flow path. High recovery inlet stages are in fluid communicating series with low recovery outlet stages and the combination provides a high performance fluid pressure reduction device with low noise generation.

Description

FLUID PRESSURE REDUCTION DEVICE This invention relates to fluid energy dissipation devices, and in particular to a fluid pressure reducing device with a low acoustic conversion efficiency for gas flows, and also for devices with anti-cavitation properties, and therefore Low noise, as they are designed for liquid flows.

BACKGROUND OF THE INVENTION Considerations involving several factors with respect to the present invention are discussed in the sections separately titled below. In particular, in connection with the fluid pressure reducing device of the present invention, the pertinent considerations discussed separately below involve: (A) Aerodynamic Noise; (B) Manufacturing; and (C) Hydrodynamic Noise.

(A) Aerodynamic Noise In the control of fluid in industrial processes, such as oil and gas pipe systems, chemical processes, it is often necessary to reduce the pressure of a fluid. For this task, adjustable flow restriction devices, such as flow control valves and fluid regulators, and other fixed fluid restriction devices, silencers, and other return pressure devices are used. The purpose of the fluid control valve and / or other fluid restriction device in a given application may be to control the flow rate or other process variables, but the restriction induces a pressure reduction inherently as a byproduct of its function of flow control. Pressurized fluids contain stored potential mechanical energy. The reduction of pressure releases this energy. Energy manifests itself as the kinetic energy of the fluid - both the movement in volume of the fluid and its random turbulent motion. Turbulence is the chaotic movement of a fluid. However, there is a momentary structure in this random movement. Turbulent currents (vortices) form, but they break quickly in small eddies that in turn also break, and so on. Eventually, the viscosity dampens the movement of the smallest eddies, and the energy has been transformed into heat. This turbulent fluid movement has associated pressure and velocity fluctuations that act on the structural elements of the pipe system, causing vibration. Vibration is undesirable, because (if it is strong enough) it can lead to fatigue failure of components that retain pressure, or other types of wear, degradation of operation, or failure of connected instruments, and so on. Even when it does not physically damage, the vibration generates noise from the air that is annoying can damage people's hearing. There are three basic methods for noise control: 1) Limit the amount of vibration generated initially. Since the amount of energy that is dissipating is established by the application, this reduction in the noise level must come from the reduction of the efficiency of the conversion of fluid energy to acoustic energy. 2) Absorb the acoustic energy. A typical example of an industrial device is a muffler packed with fiberglass. 3) Block the transmission of sound. An example would be a thick-walled tube. The portion of the total amount of energy that becomes vibration depends on the nature of the flow field and turbulence, in addition to the response or the tendency of the surrounding structure to absorb that energy.

The fraction of mechanical energy converted into noise is known as the acoustic conversion efficiency. There are several methods to minimize the noise and vibration generated by reducing the fluid pressure. In gases, the four methods frequently used are: 1) Reduce the pressure in small steps or stages, instead of using a single turbulence generating process. Usually, a pressure reducing stage is performed by a contraction / expansion of flow current, or by a change of direction. In any case, a jet of fluid is formed at a higher velocity, and is surrounded by a region of lower velocity. The resulting turbulent mixture generates noise. If the pressure change across the stage is high enough, the jet will "drown" or reach the sonic velocity, and shocks will form in the flow stream. A shock produces a sudden change in the thermodynamic state of the flow. For example, the pressure can fall appreciably. When the input turbulence passes through a shock, noise associated with the wideband shock is also generated. 2) Avoid contact of high-speed jets and turbulence on solid surfaces.

The so-called Reynolds voltages in free-current turbulence are a source of noise. However, when the turbulence makes contact with a solid surface, acoustic dipole sources result. Dipole sources are very effective sources of noise when the speed of the average current is low. 3) Subdivide the flow stream into small currents. This strategy really accomplishes multiple desirable results. Due to their smaller characteristic dimensions, small currents create higher frequency turbulence because the initial eddies are smaller. The energy has moved forward in the process of breaking the swirl, thus jumping the opportunities for vibration generation. Second, these smaller vortices contain most of their energy in a frequency range that is less easily adsorbed (and then radiated as noise) by the components of the pipe. Therefore, small currents improve the effectiveness of typical industrial piping to block the transmission of noise that is generated. Third, the human ear is less sensitive to high frequency noise, so there is a reduction in apparent noise. Fourth, it is easier to prevent these small jets from hitting a solid surface, thus minimizing dipole type noise. Finally, as long as the jets from each stream remain isolated, the noise from each stream remains uncorrelated with the others, and the total is minimized - in a manner similar to the effect of putting it in stages. The clogging of the passages by the waste of the fluid establishes a practical lower limit for the size of the current. 4) Combinations of the previous strategies. A problem with staging the compressible flow is that the pressure is reduced, and the volume of flow is increased in the following stages. For applications of high pressure ratio (inlet pressure / outlet pressure), the increase in the required flow area can be substantial. Many prior fluid restriction devices use passages with an increased flow area. For compressible flows, these restrictors are normally used in such a way that the flow is radially outward through the wall of the annular cage. This takes advantage of the natural increase in the gross cross-sectional area, to provide space for the increased passage area. The main technical challenge of reducing the noise and vibration generated by reducing the fluid pressure, is the effective implementation by the cost of the geometry of the flow path that manipulates the state of the fluid in a more effective manner.

(B) Manufacturing The formation of the desired passages in the low noise restriction elements is usually very expensive. The appropriate raw material form also affects the cost and delivery. Annular recesses or rods can be used to make cylindrical structures in many of the currently available flow restrictors - liners, rings, and so on. However, this requires many combinations of diameter, length, and thickness for the raw material. Annular discs of many combinations of internal diameter / external diameter can be cut from a common leaf, and stacked to the desired height. Forged shapes such as the blade are less likely to contain defects, such as porosity, than ring voids. Historically, disks used in piles to form a cage have been manufactured by chemical etching, lamination, electron discharge machining (EDM), casting, cutting, punching, or punching. Chemical etching is a versatile process, but it is very expensive for parts of the size needed for valve cages. In addition, the bath with acid and metals dissolved in it, present a problem of hazardous waste disposal. Lamination is expensive and has limitations for small features, due to a practical lower limit on the size of the cutter. Wire electron discharge machining is limited to cut-through designs, and is slow. The plug electron discharge machining can make recess type designs, but is more suitable for pattern making, rather than the mass production of the disks. The emptying is economical but requires an expensive hardware pattern for each version of the design. The castings may require flattening and / or grinding operations before assembling the pile. Die-cutting is limited to cut-through designs, requires a single die for die-cutting, and the discs may not be flat after the die-cutting operation. Die wear can degrade the flow handling characteristics of the desired shape of the passage. In addition, small features are not possible, especially for thick discs. The perforation limits the shape of the passage to holes and thinning of the symmetrical axis. Additionally, the spokes can not be placed on the inside of an annular cage structure by drilling. The cutting methods include plasma, laser, and erosion water jet. Clearly, these methods are limited to cross-cut designs. However, many of the cut-through designs of the previous flow restrictors do not lend themselves to effective production at cost through cutting. For example, the skeletal discs shown in Self (US Pat. No. 3,513,864) require a large number of initiations and arrests of flame / beam / jet, as the operation moves from one cut region to the next .

These starts and detentions add a substantial machine time per part, making the cost per part proportionally higher. It is desired to provide a disc design that can be done in an efficient manner with a cutting process. Additionally, the widespread availability of computer numerically controlled (CNC) machines, computer aided design (CAD) systems, and automated interfaces between them have dramatically changed the relative cost advantage of software (CNC cutting). against manufacturing processes based on physical patterns (emptying). This software-based tool is especially convenient for severe service applications that require noise control type restrictions that are often specially designed for the particular application. Normally, stacks of discs are held together by welding or screwing. Sometimes the disc-to-disk connections are soldered individually. In addition to the cost of the restrictor element, the size of the element for a given flow capacity influences the required valve body size, which in turn has a large influence on the total cost of the valve.

The traditional tortuous trajectory cuts have presented inefficient flow passages to distribute the pressure reduction. Accordingly, the flow rate per unit cross-sectional area is smaller than, for example, a two-stage device. Consequently, a restrictor based on the traditional tortuous path must be significantly larger to accommodate both the additional passage area and the extra stages per passage. This increase in restrictor size results in a very large, heavy, and expensive valve body, which requires a large actuator to operate the valve.

(C) Hydrodynamic Noise Although the physical phenomenon responsible for the generation of hydrodynamic noise in the reduction of liquid pressure is different, many of the manufacturing techniques of this invention are also convenient for use in liquid passages. In industrial applications, the main source of noise and vibration from the reduction of liquid pressure is cavitation. Cavitation is caused in a flow stream when the fluid passes through an area where the pressure is below its vapor pressure. Steam bubbles form, and then collapse after traveling downstream to an area where the pressure exceeds the vapor pressure. The collapse process can cause noise, vibration, and material attack. One method to avoid these problems is to design a passage where the pressure never falls below the vapor pressure. As with gas flows, multiple stages are often used. The number required depends on the amount of pressure reduction assigned to each stage, and the minimum pressure in each stage, compared to its overall pressure change, that is, the amount of pressure recovery. A low pressure recovery is desirable. The right-angle spin-based stages often found in the stacked plate flow restrictors exhibit pressure recovery. As a result, more laps are required; increase the complexity, size, and cost of valve assembly. As a practical matter, it is convenient to take the largest pressure drop in the first stage (where the static pressure is the highest), and progressively smaller pressure drops in the subsequent stages. This approach is sometimes described as a growing area flow path when applied to the steps based on the change of direction. As with compressible flows, a small passage size is beneficial. It is often permissible to operate under conditions that produce small amounts of cavitation. A group of small jets of two isolated phases is less efficient to excite vibration than a large two-phase jet. As a theoretical principle, speed control is an indirect means to control vibration and noise in liquids. The purpose of speed control is to minimize the effect of Bernouli, which reduces the local static pressure of a fluid due to its movement in overall volume. This relatively higher static pressure in turn minimizes the range of pressure conditions that cause cavitation. Accordingly, it is desired to provide a fluid pressure reducing device having a low acoustic conversion efficiency or hydrodynamic noise, and which can be manufactured in an efficient manner at lower manufacturing costs.

SUMMARY OF THE INVENTION In accordance with the principles of the present invention, there is provided a device for reducing fluid pressure, which includes at least two stacked disks, each having fluid passages for communicating the fluid from an inlet to an outlet . For compressible fluids, a first stage of high recovery is provided in the fluid passages, and a second low recovery stage is provided in series with the first high recovery stage. The stages of high recovery and low recovery in series in the stacked disks, are used to obtain the reduction of the desired fluid pressure with a low generation of aerodynamic noise. For liquids, a construction with all stages of the low recovery type is preferred. In another embodiment of a fluid pressure reducing device according to the invention, a plurality of stacked discs having hollow centers aligned along a longitudinal axis are provided. Each disk in the stack has: (a) slots in the fluid inlet stage that extend partially from the center of the disk to the perimeter of the disk, and (b) slots in the fluid outlet stage that extend partially from the perimeter of the disk toward the center of the disk, and (c) at least one camera slot extending into the disk. The disks are selectively placed in the stack to enable fluid flow consecutively from the slots of the fluid inlet stage in a disk, to the chamber slot in a second adjacent disk, and to the slots in the output stage of fluid in at least one disk, wherein the fluid flow path is divided into two initial axial directions, and then distributed through multiple slots of the output stage of the respective disks of the stack adjacent to the secondary disk. In another embodiment of a fluid pressure reducing device according to the invention, there is a similar plurality of discs stacked with the camera, and slot patterns configured in an alternating fashion around each disc. A camera is provided for each group of input and output slots. In another embodiment of a fluid pressure reducing device according to the invention, there are a plurality of pairs of stacked disks, wherein the input and output slots previously described are all on a disc, and the chambers are all in the coupling disk. This mode does not have the advantage of all other modes, of a softly variable flow resistance as the valve plug is traversed. Another drawback is that two different disks should be made instead of a single disk, as will be described. In another embodiment of a fluid pressure reducing device according to the invention, there is a seven stage construction, based on a plurality of stacked disks, each having: (a) partially extending fluid inlet slots from the center of the disk to the perimeter of the disk, and (b) slots of the fluid outlet stage that extend partially from the perimeter of the disk to the center of the disk, and (c) at least one camera slot that is extends inside the disk. In this embodiment, the grooves have a shape that forms more than one contraction / expansion of the fluid passage (compared to the previous modes) per slot length. Again, the discs are selectively positioned to enable the fluid to flow from one stage to the next through the complementary slot and chamber patterns of the adjacent discs. These complementary patterns can be configured in an alternating fashion within a single disk design. In this modality with many stages, there may be an overlap of the considerable slot area, allowing unimpeded axial flow through the stack. This may be undesirable, especially for liquid applications, so that a small fit is added periodically in the stack sequence. It should be apparent to those skilled in the art, that modalities with three to six stages (or more than seven) can be deduced from the teachings of this invention. In a preferred embodiment of the invention, a plurality of stacked annular discs having perimeters and with hollow centers are provided, wherein each disc has the same complementary pattern of slots grouped into groups. According to the foregoing, each disk is identical to a plurality of fluid inlet stages, each having slots that extend partially from the center of the disk towards the perimeter of the disk. Each slot of the fluid inlet stage includes corner radii to prevent the flow from separating as it passes through the stage, and with thinned side passages to make each inlet stage a high recovery stage with low generation of resulting noise. At the end of the thinned lateral passages, a rear slot portion of a limited size is provided to communicate with the upper and lower chambers of the respective adjacent upper and lower disks, as will be explained later herein. Each disc further includes a plurality of fluid outlet stages located on the perimeter of the disc, and on the same circumferential side as the inlet stages, with each outlet stage including slots extending partially from the perimeter of the disc to the center of the disc. disk. Each of the exit stage slots has converging side passages, in order to make these downstream stages low recovery stages with low resulting noise generation. Each of the output stage slots further includes a front slot portion for communicating with the upper and lower chambers of the respective adjacent upper and lower disks. Each disc further includes chamber areas comprising slots located entirely inside the disc on the opposite circumferential side of the disc from the slots of the entry and exit stages. The disks are configured in the stack in sets of four sub-stacks, wherein the second disk overlaps the first disk, the input and output stages of the second disk overlapping the chamber portions of the first disk. The third disk of the sub-stack is in the same position as the first disk, with the exception that the third disk is inverted horizontally. Accordingly, the third disk chamber portion overlaps the portions of the second disk input and output stages. Finally, the upper part of the fourth disk in the sub-stack is placed just like the second disk, except that it is flipped. In accordance with the above, the input and output steps of the upper disk overlap the camera portions of the third disk. Also, inside each disk, the slots of the input stage, as well as the slots of the output stage, are configured in an asymmetric manner inside each disk. Accordingly, this asymmetric arrangement of the inlet and outlet slots, together with the previous disk stacking sequence, makes it possible for a fluid communication portion of the inlet and outlet slots to be aligned with the area of the inlet and outlet slots. chamber of a sandwich disk, but prevents an uninterrupted direct axial flow path through the slots. Accordingly, in the preferred embodiment, the fluid flow path to the hollow central portion of the stacked discs encounters multiple inlets, each formed as a high recovery stage. Next, the fluid flow is divided into an upper and a lower axial direction, passing through a posterior slot portion at the end of the high recovery stage., whose rear groove portion is aligned with a respective chamber area on an immediately adjacent upper and lower disc. Each of the divided flow paths now flows radially and is distributed in a circumferential manner in the respective chambers, and expands to reach the slots of the output stage, providing a low recovery stage on the perimeter of an upper disk, as well as a lower disk immediately adjacent to each of the respective chambers containing the radial flow path. Now, in each of the chambers, the flow path extends axially upwards, as well as axially downwards, through a front slot portion of the outlet slots, which communicate with the adjacent chambers. The flow in each of the axial directions is now combined in one or more of the outlet slots, so that multiple outward radial flow directions are obtained through the multiple stages of low recovery. In the preferred embodiment for gas flows, it is desired that each of the high recovery inlet stages operate at a pressure ratio above about 2, in order to intentionally reduce the generation of noise. In addition, it is desired that the multiple low recovery output stages operate at a pressure ratio of less than about 2, in order to intentionally reduce the generation of noise. This provides a high-performance gas pressure reducing device with low noise generation. The modalities just discussed are presented as devices, with the fluid passing radially outward through the wall of the disk stack. It should be apparent to the person skilled in the art that the construction can be reversed from the exit stage to the entry stage, creating a device for the flow to pass radially inward. A device for reducing fluid pressure in accordance with the principles of the present invention includes the following structural characteristics and operating characteristics and advantages: 1) minimizes the generation of aerodynamic noise by the construction of a geometry of flow passages that conveniently controls flow separation, shock formation, pressure recovery, and fluid turbulence characteristics. 2) For liquid flows, minimizes the propensity to cavitation by constricting a geometry of flow passages that controls flow separation and pressure recovery. 3) Implement this geometry of desirable flow passages from a standard raw material form to reduce inventory and shorten delivery. 4) It implements this geometry of desirable flow passages in a device that can be manufactured in an effective way by cost using modern techniques - CNC controlled laser, or water jet cutting, and so on. 5) Minimizes the overall cost of the valve by shrinking the size of the pressure reducing element, compared to the designs of the tortuous path principle currently used. 6) Provides a fluid control valve with a resistance element that varies smoothly with respect to the position of the plug, to improve the operation of the control. 7) It provides an effective element for the cost to rigidly assemble a stack of discs during manufacture and use, which also allows disassembly for repair or cleaning. 8) Provides a fluid control element that can be tailored for special applications without excessive tool costs. It should also be noted that some conventional pressure reducing devices lead to fluid flow in a three-dimensional tortuous flow path, such as radial zig-zag, to exit the device at a level of the output location different from the location level. of entry. By contrast, the devices of the present invention provide a three-dimensional flow movement with the output location on the same level as the input.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristics of this invention that are believed to be novel, are stipulated with particularity in the appended claims. The invention can be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the different figures, and in which: Figure 1 is a cross-sectional view which illustrates a fluid control valve containing a valve cutout in the form of stacked discs forming a fluid pressure reducing device in accordance with the present invention.

Figure 2 is a plan view of an annular disk forming each of the stacked disks of Figure 1. Figure 3 is a perspective view of four disks as in Figure 2, selectively placed in a subset of four disks in accordance with the invention. Figure 4 is a fragmented perspective view illustrating the stacked disks of Figure 1, with a schematic representation of the fluid flow path therethrough. Figure 5 is a schematic flow diagram illustrating the flow path through the stacked disks, as seen in a side view. Figure 6 is a schematic flow diagram illustrating the fluid flow path through the stacked disks in a plan view. Figure 7 is a plan view of another disk embodiment with alternating slots and chambers. Figures 8 (A) and 8 (B) are seen in respective plants of yet another disk mode, with all the slots in one disk, and all the cameras in the other disk. Figure 9 is a plan view of an additional disk embodiment, with screws, to hold the disks in a stacked configuration. Figure 10 is a plan view of a still further disk embodiment, with multiple stages of fluid processing. Figure 11 is a perspective view of a fragmented portion of four disks, each as in Figure 10, selectively placed in a subset of four disks, in a multi-stage embodiment of the invention.

Detailed Description Referring now to Figure 1, there is illustrated a device for reducing fluid pressure in accordance with the principles of the present invention, in the form of a valve cage 10, having a plurality of stacked disks, and mounted inside of a fluid control valve 12. The fluid control valve 12 includes a valve body 14 that includes a fluid inlet 16, a fluid outlet 18, and a connection passage 20 through the valve body . A seat ring 22 is mounted within the passage of the valve body 20, and cooperates with an operative valve member 24 for controlling the flow of fluid inwardly and through the exterior of the valve cage 10. The valve cage 10 it can be kept inside the valve by a conventional mounting element, such as a cage fastener 26, and mounting screws 28 which engage the bonnet portion of the valve in a known manner.

The valve cage 10 includes a plurality of stacked disks, each of which is identical to a disk 30, as shown in Figure 2. The disk 30 includes a hollow central portion 32 and an annular perimeter 34. On one side of the disc 30, a plurality of slots of the fluid inlet stage 36 are provided, each extending partially from the center of the disc 32 towards the perimeter of the disc 34, and a plurality of slots of the fluid outlet stage 38, each extending partially from the perimeter of the disk 34 towards the center of the disk 32. On the circumferential side of the disk opposite the slots of the fluid inlet and fluid outlet stages, one or more chamber slots 40 are provided., which extends entirely inside the disc from an end 42 adjacent one end of the fluid inlet and outlet slots, to an opposite chamber end 44 adjacent to the opposite end of the fluid inlet and outlet slots. The chamber 40 also extends between an inner portion of the disk 41 adjacent the hollow central portion 32, and an outer portion of the disk 43 that terminates at the perimeter of the disk 34. A small support bridge 45 connects the disk portions 41, 43, and divide the camera 40 into two chamber sections. As shown in Figure 2, two opposite holes 46 are provided on each disk. The holes 46 through each disk 30 accommodate a pair of orientation pins to orient each of the discs 30 within the stacked configuration. As can be seen in Figure 2, the pitch of the orientation pins through the mounting holes 46 in each of the discs 30 is provided in a manner that does not interfere with the flow of fluid through the cage of valve 10. A series of welding projections 48, as shown in Figure 1, on the outside of the valve cage 10, securely holds the disks 30 in an assembled stack. Each of the slots in the fluid inlet stage 36 is formed with corner radii 50 which tend to prevent the flow of fluid from separating from the surface of the disk as it passes through the first inlet stage. Also, the tapered lateral passages 52 inside each of the slots 36 provide a high recovery stage for each of the fluid inlet stages. As an example, the opposite lateral passages 52 are tapered to diverge radially outward at an included angle of approximately 15 °. At the end of each of the slots in the fluid inlet stage 36, a rear slot portion 54 of a limited size, and yet sufficient to communicate the fluid to the adjacent chambers 40 in the adjacent upper and lower discs is provided. , as will be described later herein.

Each of the slots in the fluid outlet stage 38 is formed with a front slot portion 56, of sufficient size to communicate with a chamber 40 in the adjacent upper and lower disks. The converging side passages 58 converge outwardly from the front slot portion 56 towards the perimeter of the disk 34, to provide a low recovery stage for each of the slots in the fluid outlet stage 38. The high inlet stages Recovery and low recovery exit stages are designed to provide low noise generation. Reference may be made to the document entitled Coefficients and Factors Relatinq to Aerodvnamic Sound Level Generated by Throttlincr Valves, by Hans D. Baumann, in the Noise Control Engineering Journal January-February 1984. The contents of this document are expressly incorporated herein by reference. reference, to demonstrate the state of the art with respect to acoustic efficiency as a function of pressure recovery. According to this document, it is recognized that the acoustic efficiency (in other s, the capacity to generate noise) will vary as a function of the degree of pressure recovery (FL factor over a range of pressure proportions) for the inlet valves and departure) . The continuous passages have low FL factors, and an abrupt discharge area has a high FL factor that can be close to 1.0. By providing a small cross-section in the inlet, and a thinned flow path towards the outlet, a low FL is provided. This low FL is suitable for high proportions of pressure through the stage that are greater than 2: 1, since this generates a lower acoustic efficiency, usually 5-10 dB, over that of a high FL passage. However, when the pressure ratio is low (less than 2: 1), a high FL is preferred for a lower acoustic efficiency, typically 5-10 dB lower. Accordingly, a range of sizes and slot configurations can be employed to tailor a low noise output section for the given pressure conditions of the valve in its normal operating range. In the preferred embodiment of the invention, it is desired that each of the high recovery input stages 36 operate at a pressure ratio greater than about 2, in order to intentionally reduce the generation of noise. In addition, it is desired that each of the multiple low recovery output stages 38 operate at a pressure ratio of less than about 2, in order to intentionally reduce the generation of noise. This makes it possible for the valve cage 10 to provide a high performance fluid pressure reduction with a low noise generation.

Referring now to Figure 2, it can be seen that there is a reference character A on one side of disk 30, and a reference character B on the opposite side of disk 30. These reference characters A, B will be useful for understanding the orientation of the disks 30 inside a stacked disc assembly according to the invention. Also, it can be seen from Figure 2, that the slots of the fluid inlet stage 36 are not symmetrically arranged on the disc with respect to the chamber 40. In particular, note that the last slot of the inlet stage of fluid 36 on the left side of Figure 2 adjacent to the end of chamber 42, is much closer to the end of chamber 42 than the last slot of the fluid inlet stage opposite to the right 36 with respect to the end of the opposite chamber 44. The same asymmetric configuration can be observed with respect to the slots of the fluid outlet stage 38 and the chamber ends 42, 44. This is an important feature of the present invention, to ensure that, when assemble the discs 30 in the stacked disc assembly in the selective manner shown in Figure 3, there is no uninterrupted direct axial fluid flow through the slots. Accordingly, substantially all of the fluid flow will extend from the slots in the fluid inlet stage 36 through the chamber 40, and eventually out through the slots in the fluid outlet stage 38. Now doing Referring to Figure 3, a subset of four identical discs 30 is shown in a separate view in parts, so that the relationship and selective placement of each disc can be more easily described and illustrated. It should be understood that the valve cage 10 contains stacked discs, which include groups or subsets of four discs 30, as shown in Figure 3, stacked on top of each other. In Figure 3, you can see the lowermost disc 30a in the same position as the disc 30 shown in Figure 2 with reference to the character B visible on the upper disc surface. The next disk 30b is placed by rotating the disk 180 °, so that the reference character A above the reference character B of the lower disk 30a can be seen. The next disk 30c is placed taking the disk 30 of Figure 2, and turning it over, so that the reference character B is no longer visible, and is placed above the visible reference character A of the lower disk 30b. Finally, the uppermost disk 30d is placed over the disk 30 of Figure 2, so that the reference character A can no longer be seen, and is substantially in line with the invisible reference character B of the disk 30c, the visible reference character A of the disk 30b, and the visible reference character B of the lowermost disk 30a.

As indicated above, the slots of the fluid inlet stage 36 and the slots of the fluid outlet stage 38 are configured asymmetrically on the disk with respect to the holes for the orientation pins 46, and specifically with respect to the camera ends 42, 44. This asymmetric configuration of the slots 36, 38, together with the selective placement of the discs 30a-d, as shown in Figure 3, precludes an uninterrupted axial flow path in the assembly. stacked discs. Additionally, this feature prevents the excitation of an acoustic column resonance that could be presented with an axial chamber without obstructions. Referring now to Figures 4, 5, and 6, the manner in which the fluid flow path extends as a three-dimensional flow movement through the valve cage 10 is illustrated. For convenience in a description of the flow path, the lowermost disc 30a and the following upper discs 30b, 30c, and 30d, are similarly referenced in Figures 3 and 4, as well as in Figures 5 and 6 to the extent possible, in view of the nature Schematic of Figures 5 and 6. Initially, the fluid flow in the hollow central portion 32 enters each of the slots of the fluid inlet stage 36. For greater convenience in the illustration and description, the path of three-dimensional flow through one of the slots of the fluid inlet stage 36 to multiple exit stages 38. Note particularly that, although a three-dimensional flow movement is provided through the stack discs However, the output is still conveniently on the same level as the entrance. As an example, the fluid enters the slot of the fluid inlet stage 36a in the disk 30b. The fluid flow proceeds between the thinned passages 52, and up to the rear slot portion 54, to extend axially upwards, as well as axially downwards, through the rear slot portion 54, and into the chambers 40 of the bottom disc 30a, as well as the upper disk 30c. After dividing in two initial axial directions, the fluid flow now extends to multiple directions of radial flow within the chamber 40a of the disc 30a, as well as in the chamber 40c of the disc 30c. Next, the fluid flow encounters a plurality of respective forward slot portions 56 of the slots of the respective output stage 38. As an example, each of the fluid flow paths of the chambers 40a and 40c, finds the front slot portion 56a, such that the flow streams flow axially upward and axially downward respectively through the front slot portion 56a, and outwardly from the slot of the respective fluid outlet stage 38a of the disc 30b. It should be understood that this is only an example of the flow of fluid from the chambers, passing through an outlet slot. In fact, the fluid flow of the chambers 40a and 40c is distributed circumferentially through multiple radial slots of the output stage 38. For example, referring to Figure 5, note that the initial fluid inlet to disk 30b is first divided into two initial axial directions to reach lower disk 30a and upper disk 30c, and then extend in multiple directions of radial flow in of the respective chambers 40a and 40c. In the exit stages, for example, the flow into chamber 40c extends axially downward through different portions of front slot 56 of the slot of the respective exit stage 38 (see Figure 6) in the lower disc 30b, as well as extending axially upwards through another plurality of front slot portions 56 of the slots of the respective output stage 38 in the upper disk 30d. Note that the multiple radial flow directions inside the chamber 40a are also divided toward an upper disk 30b, as well as toward a lower disk (not marked in Figure 5). Figure 6 illustrates that, inside each of the respective discs 30d, 30b, and the unmarked disc of Figure 5, that the flow is circumferentially distributed through, and finally out of, multiple radial outlet slots 38. For example, from the chamber 40c, the flow is circumferentially distributed through many front slot portions (such as 50a, b, c, etc.) to multiple outputs on the disk 30b, such as 38a, b, c, and so on. . In accordance with the above, because the large chambers feed many output slots provided in the valve cage 10, according to this invention, any plugging or blocking of a few of the slots of the output stage does not alter a Significantly the operation of this device. This is a significant advantage over prior conventional devices that use a tortuous flow path, where a blockage in any passage of the path can completely stop the flow. Also, it can be seen that the preferred embodiment has a smooth linear characteristic, because each disk 30 has both inputs and outputs, and there are no "dead spots", such as in previous tortuous flow path devices. Other characteristics of non-linear flow versus distance cables could be obtained by varying the number of inputs and outputs in some of the disks. As can be seen in the embodiment of Figure 2, the complementary slot patterns are grouped into two groups, rather than scattered in an alternating fashion around the circumference of the disk. Also, equal pressure chambers can be consolidated into a single large chamber, which eliminates many starts and stops of a flame / beam / cutting jet during fabrication. This also substantially reduces the perimeter (cut length). As can be seen, the grouping of complementary groove patterns into groups leads to a single disk design 30 for the complete valve cage 10. A full flow path is determined by appropriately sequencing the orientations of the disks. You can use two or more groups on a single disk. A disc of two groups, such as in Figure 2, leads to a four-layer cage subset, as shown in Figure 3, while a three-group disk leads to a six-layer cage subset. The convenient fluid design characteristics of the slot passages reduce the number of steps necessary for a given attenuation, thereby minimizing the size and complexity of the elements. Referring to Figure 2, it can be seen that the disk 30 contains all the slots 36, 38 on one half of the disk, and the cameras 40 on the other half. An alternative disc 60 shown in Figure 7 contains alternating groups of slots, i.e., inlet slots 62 and outlet slots 64, and cameras 66, around the entire circumference of the disc. A camera 66 is provided for each group of input and output slots. Using disk 60 with the alternate pattern of slots and cameras shown in Figure 7, a two-disk cage subassembly 60 is required in a stacked sequence, such that a three-dimensional flow movement is provided, and the fluid outlet is still provided on the same level as the fluid inlet. However, in the embodiment of Figure 7, it is difficult to efficiently implement the asymmetric groove pattern that blocks uninterrupted axial flow. The advantage of the slot and camera configuration of Figure 7 is that it offers substantially more rigidity than a configuration having longer chambers as in Figures 2 and 8. Accordingly, the allowable pressure drop is increased. Further, as can be seen in Figure 7, each of the fluid exit stages 64 has straight sides 65 in the grooves, instead of the oblique sides 58 of the disc 30. The straight side grooves in the exit stage 64 are not as efficient as oblique slots to provide low acoustic conversion efficiency for the device. However, straight sides are easier to construct with conventional cutting techniques than oblique sides. It is understood, of course, that instead of the straight-sided slots, oblique-side slots, such as in the disk 30, can be used in order to provide a more efficient low-recovery stage for the output stage. of fluid 64 if desired. Figures 8 (A) and 8 (B) show another alternative configuration of a disk pattern. In Figure 8 (A) the disc 68 contains all of the fluid inlet slots 70 and the fluid outlet slots 72 located around the circumference of the disc 68 in a pattern of four groups (i.e., four respective groups of slots). of entry and exit). With reference to Figure 8 (B), it can be seen that the companion disk 74 has four cameras 76 located around the circumference of the disk. The use of discs 68 and 74 requires a subset of four-disc cage to provide three-dimensional flow movement, the fluid outlet being on the same level as the inlet, and interruptions to axial flow as in the previously described modes of the invention. The embodiment of Figures 8 (A) and (B) requires that two different disks be made and stacked in place of the single disk of the other modes. Also, this embodiment does not provide a smoothly variable flow resistance, since the valve plug is traversed in contrast to the other modes having a smooth linear characteristic. It can be seen that the pattern of the groove can be varied over the sequential discs to change the pressure drop across the device, and the flow capacity if desired. For example, fewer input slots may be provided on one or more disks, compared to the following disks in the stream stream. The advantage of a single required disk or two required discs can be lost; however, the ability to vary the valve flow characteristic (flow versus travel) may be more desirable. Figure 9 shows an alternative disc 78 having slots in the fluid inlet stage 80, slots in the fluid outlet stage 82, and chambers 84, and further including four openings 86. The openings 86 are adapted to accommodate a respective screw 88, which can be inserted through each of the openings 86 of each of the discs 78 of a stacked disc configuration, to keep the stacked discs screwed together. The use of a bolted assembly eliminates the need for the welding projections 48 of Figure 1. It can be seen that the series of screws 88 does not proportionally reduce the flow capacity of the stacked disc assembly, due to the location of the common chamber of the present invention. In each of the previously described embodiments of the invention, a two-stage design has been used, wherein the fluid passes through an inlet stage, and is coupled through a chamber with an exit stage. In an alternative way, multiple stages of pressure reduction can be provided, where this is desirable. An example of a multi-stage pattern in accordance with the present invention is shown in the plan view of Figure 10, showing a disk 90 with seven stages, and the perspective view of Figure 11 showing a subset of the stage. of four disks 90. With reference to Figure 10, the disc 90 includes a series of input slots of the first stage 92, chambers 94, slots of the second stage 96, chambers 98, and so on, leading to the slots of the seventh final exit stage 100. As seen in Figure 10, slots 92, 96, 100 have a shape that forms more than one contraction / expansion of the fluid passage per slot length. Reference may be made to Figure 11, where the perspective view shows the coupling of the fluid from the input slot 92 through the three-dimensional flow through the subset of four disks 90, to finally exit at the exit stage 100 to the same level as the input stage 92. Of course, it is understood that the fluid flow through the seven stages incorporated in the stack disc configuration shown in Figure 11 is the same as the flow through the configuration of two stages described above, that is, from one stage to the next, by means of the complementary patterns of slots and chambers of the adjacent discs.

This seven-stage mode is particularly useful for liquid flow applications. However, due to the multiple stages, there may be a considerable overlapped slot area that allows unwanted axial flow through the stack without unwanted impediments, so that a thin fit can be added periodically in the stack sequence to avoid this problem. In accordance with the teachings herein, those skilled in the art can provide alternative modalities with three to six stages (and more than seven). Although the present invention relates to the inclusion of the fluid pressure reducing device of this invention in a drowning fluid control valve, it is understood that the invention is not limited in that way. The device can be implemented as a fixed restriction in a pipe, either upstream or downstream of a control valve, or in a manner entirely independent of the location of a control valve. The above detailed description has been given for clarity of understanding only, and unnecessary limitations thereof should not be understood, since the modifications will be obvious to those skilled in the art.

Claims (28)

1. CLAIMS 1. A fluid pressure reducing device, which comprises: a plurality of stacked annular disks having a perimeter and hollow centers aligned along a longitudinal axis; including each disk multiple first high recovery stages located in the hollow center to receive the fluid inlet, and multiple second low recovery stages in a series of fluid communication with the first stages of high recovery, and located in the perimeter; providing the first high recovery stage and the second low recovery stages coupled in series, the desired fluid pressure reduction with a low noise generation. A fluid pressure reducing device according to claim 1, wherein each disk further includes a chamber that fluidly connects a first high recovery stage of an adjacent disk of the stack, with at least one second low stage. Recovery of the adjacent disk. 3. A fluid pressure reducing device according to claim 2, wherein the chamber of a disk also fluidly connects a first high recovery stage of an adjacent disk of the stack, with a plurality of second stages of low recovery. in the respective disks of the stack adjacent to this first disk. A fluid pressure reducing device according to claim 3, wherein each of the multiple stages of high recovery is radially aligned around a portion of the hollow center of the disk, and each of the multiple stages of lowering Recovery is radially aligned around a portion of the perimeter of the disk. 5. A fluid pressure reducing device according to claim 4, wherein the multiple high recovery stages and the multiple low recovery stages are located on the same circumferential side of each disk. A fluid pressure reducing device according to claim 5, wherein the chamber is disposed on the opposite circumferential side of each disc from the multiple stages of high recovery and the multiple stages of low recovery. A fluid pressure reducing device according to claim 6, wherein the multiple stages of high recovery and the multiple stages of low recovery are located asymmetrically on each disk with respect to the chamber, to prevent a flow of fluid uninterrupted axial through the stacked disks. 8. A fluid control valve, which comprises: a valve body including a fluid inlet, a fluid outlet, and a connecting valve body passage; a valve seat mounted in the passage of the valve body; an operating valve member adapted to cooperate with the valve seat in order to control the flow of fluid through the passage of the valve body; a valve cage mounted above the valve seat and in the passageway of the valve body, to reduce the fluid pressure, including this valve cage: a plurality of stacked annular disks having a perimeter and hollow centers aligned to the along a longitudinal axis; including each disk multiple first high recovery stages located in the hollow center, to receive the fluid inlet, and multiple second low recovery stages in a series of fluid communication with the first stages of high recovery, and located in the perimeter; providing the first high recovery stage and the low recovery second stages coupled in series the desired fluid pressure reduction with low noise generation. 9. A fluid pressure reducing device, which comprises: a plurality of stacked discs having a perimeter and hollow centers aligned along a longitudinal axis; each disk having: (a) slots of the fluid inlet stage extending partially from the center of the disk towards the perimeter of the disk, and (b) slots of the fluid outlet stage extending partially from the perimeter of the disk. disk towards the center of the disk, and (c) at least one camera slot extending through the disk; the disks being selectively placed on the stack to enable the flow of fluid from the slots of the fluid inlet stage of a disk to the chamber slots of the adjacent disks, and to the slots of the fluid outlet stage of when less a disc, where the fluid flow path is divided into two initial axial directions, then into the chamber slots with multiple radial flow directions, and then distributed through multiple slots of the exit stage in the when less a disc. A fluid pressure reducing device according to claim 9, wherein the chamber groove in the adjacent disc also makes possible the flow of fluid from the slots of the fluid inlet stage of a disc, to be coupled with the multiple slots of the fluid outlet stage in the respective disks of the stack adjacent to said adjacent disk. A fluid pressure reducing device according to claim 10, wherein the slots of the fluid inlet stage are radially aligned about a portion of the hollow center of the disk, and the slots of the outlet stage are radially aligned around a portion of the perimeter of the disk. 12. A fluid pressure reducing device according to claim 11, wherein the slots of the fluid inlet stage and the slots of the fluid outlet stage are located on the same circumferential side of each disk. A fluid pressure reducing device according to claim 12, wherein the chamber slot is disposed on the opposite circumferential side of each disc from the slots of the fluid inlet stage and the slots of the stage of fluid outlet. A fluid pressure reducing device according to claim 13, wherein the slots of the fluid inlet stage and the slots of the fluid outlet stage are located asymmetrically on each disk with respect to the chamber, to prevent an uninterrupted axial fluid flow path through the stacked disks. 15. A fluid pressure reducing device according to claim 9, wherein each of the slots of the fluid inlet stage includes corner radii, to substantially prevent fluid flow separation, and further includes passages. laterals diverging outwards, to provide a high recovery stage. 16. A fluid pressure reducing device according to claim 15, wherein each of the fluid inlet slots includes a rear slot portion that communicates fluidly with the chamber slot in the respective adjacent disks of the battery. A fluid pressure reducing device according to claim 16, wherein each of the slots in the fluid outlet stage includes converging lateral passages to provide a low recovery stage. 18. A fluid pressure reducing device according to claim 17, wherein each of the slots in the fluid outlet stage includes a front slot portion that communicates fluidly with the chamber slot in the disks. respective adjacent of the stack. 19. A fluid pressure reducing device according to claim 18, wherein the slots of the fluid inlet stage and the slots of the fluid outlet stage are located asymmetrically on each disk with respect to the chamber., to prevent an uninterrupted axial fluid flow path through the stacked disks. A fluid pressure reducing device according to claim 9, wherein the slots of the fluid inlet stage are configured to provide a high recovery stage, when the pressure ratio of the inlet pressure to the chamber pressure is greater than about 2. 21. A fluid pressure reducing device according to claim 9, wherein the slots of the fluid outlet stage are configured to provide a high recovery stage, when the The pressure ratio of the chamber pressure to the outlet pressure is greater than about 2. 22. A fluid pressure reducing device according to claim 9, wherein each disc includes multiple passages of contraction fluid flow. and expansion through the stage slots and camera slots. 23. A fluid pressure reducing device according to claim 22, wherein each of the multiple stages is a low recovery stage. 24. A fluid pressure reducing device according to claim 9, which includes welding projections that extend along the perimeters of the disks to keep the stacked disks assembled together. 25. A fluid pressure reducing device according to claim 9, wherein each disk includes spatially spaced mounting apertures on the disk, and this device includes a plurality of elongate fasteners, each adapted to pass through a respective opening of each of the disks, to keep the stacked disks assembled together. 26. A fluid control valve, which comprises: a valve body including a fluid inlet, a fluid outlet, and a connecting valve body passage; a valve seat mounted in the passage of the valve body; an operating member of the valve adapted to cooperate with the valve seat, in order to control the flow of fluid through the passageway of the valve body; a valve cage mounted above the valve seat and in the passageway of the valve body, to reduce the fluid pressure, including this valve cage: a plurality of stacked discs having a perimeter and hollow centers aligned along the length of a longitudinal axis; each disk having: (a) slots of the fluid inlet stage extending partially from the center of the disk towards the perimeter of the disk, and (b) slots of the fluid outlet stage extending partially from the perimeter of the disk. disk towards the center of the disk, and (c) at least one camera slot extending into the disk; the disks being selectively placed in the stack to enable the flow of fluid from the slots of the fluid inlet stage in a disk to the chamber slot of a second adjacent disk, and to the slots in the fluid outlet stage of the disk. at least one disc, wherein the fluid flow path is divided into two initial axial directions, then into the chamber groove with multiple radial flow directions, and then distributed through multiple slots of the output stage in the at least one disc, where the valve cage provides the desired fluid pressure reduction with a low noise generation. 27. A fluid pressure reducing device, which comprises: a plurality of stacked discs having a perimeter and hollow centers aligned along a longitudinal axis; each disk having one of: (a) slots of the fluid inlet stage extending partially from the center of the disk towards the perimeter of the disk, and slots of the fluid outlet stage extending partially from the perimeter of the disk towards the center of the disk, and (b) at least one camera slot extending through the disk; the disks being selectively placed on the stack to enable the flow of fluid from the slots of the fluid inlet stage of a disk to the chamber slots of the adjacent disks, and to the slots of the fluid outlet stage of when less a disc, where the fluid flow path is divided into two initial axial directions, then into the chamber slots with multiple radial flow directions, and then distributed through multiple slots of the exit stage in the when less a disc. 28. A fluid pressure reducing device, which comprises: a plurality of stacked discs having a perimeter and hollow centers aligned along a longitudinal axis; including the stacked disks first and second alternating disks; the first disc having: (a) slots of the fluid inlet stage extending partially from the center of the disc towards the perimeter of the disc, and (b) slots of the fluid outlet stage extending partially from the perimeter from the disk to the center of the disk; having the second disk: (c) at least one camera slot extending through the disk; and the disks being selectively placed in the stack to enable the flow of fluid from the slots of the fluid inlet stage of a disk to the chamber slots of the adjacent disks, and to the slots of the fluid outlet stage of the disc. at least one disc, where the fluid flow path is divided into two initial axial directions, then into the chamber slots with multiple radial flow directions, and then distributed through multiple slots of the output stage when less a disc.