CA2870564C - Anti-cavitation device - Google Patents

Abstract

An anti cavitation conditioner compact device, paddle type used in conjunction with conventional control valves, installed at valve inlet to dissipate fluid energy by limiting liquid fluid pressure and velocity to provide normal differential pressure across the valve and consequently eliminate the cavitation problem of the valves. The device comprises of two integral pressure and flow conditioner perforated orifice plates, having different hole sizes with no central holes, made of stainless steel for insertion in upstream the conventional control valve's flange, or piping system used with standard valves raised face or ring type joint flanges, facing fluid severe process condition wherein the first pressure conditioner plate absorb a pre- determined differential pressure, the second plate with smaller size perforations act to dissipate fluid velocity energy and provide downstream normal process condition to the valve to achieve higher cavitation index, and finally eliminate cavitation problem, erosion, in liquid valves and generated noise in gas valves, the device designed for each valve process condition.

Description

Nov.17.2016 Application No. : 2,870,564 Owner : Nadeem, Mahmoud Shaker Title : Anti-Cavitation device Classification : F16L 55/02 (2006.01) Filing date : December 01.2014 The Description 1. Technical Field The present invention relates to elimination of cavitation and noise in process equipment, piping system, and particularly to control valves using perforated restriction plates as flow and velocity fluid conditioner where the flowing liquid high pressure and velocity subjected to control valves or process equipment cause damages to valve's trim and body internals. The device is used to dissipate the fluid pressure and velocity energy by using perforated restriction plates conditioners designed according to each process service condition, used in conjunction with the conventional valve to avoid the damages of valves and implement un expensive construction material.

2. Background of the Invention The conventional control valves handling fluids under high pressure are subjected to cavitation and noise problem. Many prior arts had been suggested for replacing the conventional valves trim by perforated cage trim type or other types trim to cause the fluid to flow through serpentine or tortuous passages directions, resulting in dissipation of energy inside the valve either through friction or through multiple changes of direction, or by a combination of both. Many prior art devices have been suggested for the use of flow restrictor means effecting energy dissipation which usually takes place inside the valve by using new anti-cavitation valve trim. Manufacturers of such constructions control valves are:
US-Patent 4221037 by Cope-Vulcan Inc. on 29 Sep 1977, Patent name "Method for manufacturing a fluid control device with disc-type flow restrictor" in which new flow restrictor comprises an axial stack of annular discs used in the valve trim.
US patent 3780767 by Masoneilan Int', Inc. on 25 Dec 1973 Patent name: "Control valve trim having high resistance vortex chamber passages" which discuss control valve trim perforated cage having high resistance, fluid flow energy absorbing, vortex chamber passages opening between the cage bore and circumference.
US patent 4279274 A granted to Fritz 0. Seger- Copes-Vulcan Inc. on 21 July 1981, patent name: "Fluid control device with disc-type flow restrictor" in control valve which discuss a new structure, the valve trim includes a form of flow restrictor, which serves to limit flow velocity and causes the fluid pressure to be reduced in a sufficient number of discrete stages to minimize noise and cavitation.
US patent US3856049 A granted to Schull W.- Leslie Inc. on 24 Dec 1974, patent on "Multiple stage restrictor" discuss multiple stage restrictor inside the valve arranged by a plurality of stage restrictor inside the valve al i-anged by a plurality of stacked plates, relatively decreases velocity defining flow-restricting peT:54ages throLigh which the fluid flows.
US patent 5941281 A granted to Hans D. Baumann on 24 Aug 1999 'Fluid pressure reduction device" which discuss A fluid pressure reduction valve trim with low noise generation. A stack of annular disks with fluid paseageways formed of irilot slots, outlet slots inside a valve.
US patent 5R19130.3 A, granted to Kim W Lebo, SPkhar Samy on 13 Oct 1998, for "Fluid pressure reduction device" which discuss a fluid pressure reduction device used in a valve, includes a plurality of flow resistance modules forming a serpentine flow path which effectively reduce the pressure in extremely high-pressure fluid flows. Restriction conditioner devices which provide pressure reduction flowing fluids by perforated plate means to attain energy losses, an example of such a now conditioner is the invention described in U.S. Patent No. 5,762,107, .That patent disclosed adding vanes parallel to the flow, both upstream and downstream to the perforated plate. Similarly, U.S. Patent No. 6,701,963-, discloses a low pressure drop flow conditioner using porous axial vanes, also:
US patent 3954124 A, granted to Richard E. Self on 4 May 1976 for "High energy loss nested sleeve fluid control device"
which discuss a cage with nested concentric sleeves or tubes ¨
for an energy loss- subdivide flow of fluids through a fluid

3 control valve into a myriad of streams between the valve inlet and outlet which flow through passages that create a high energy loss and pressure drop on the fluid to release the fluid at low pressures without generating noise by using a cage being composed of a plurality of nested concentric tubular sleeves in the valve.
US patent 20060096650 Al, granted to Blaine Sawchuk, Dale Sawchuk on May 11 2006, subject "Non-linear noise suppressor for perforated plate flow conditioner" which implement the perforations (holes) in the plate installed ahead of flow meter which cause the fluid flow to be reconfigured or readjusted to develop a fluid flow velocity profile for the flow meter in a more accurate and repeatable fashion.
US patent US4593446 A, granted to Paul F. Hayner on 10 June 1986 for "Method of manufacturing a fluid flow restrictor"
discuss manufacturing of fluid flow restrictors formed of a plurality of annular plates incorporated into a submarine valve stacked concentrically and brazed together to form the fluid flow restrictor using tortuous paths. Fluid flow restrictors are employed to effect a pressure drop in a hydraulic system employed with valves used in submarines and the like wherein a low noise environment is required.
It is apparent from the foregoing that the prior art implement replacing the conventional control valves by special expensive material construction trim complete valves. Others patents using screen plate construction for noise and cavitation problem for customized process applications, or process equipment but failed to discuss, show, or suggest a patented device to

4 handle the severs process condition of the conventional valve individually and perform same solution to the problem outside the valve to treat cavitation problem in conjunction with the conventional valves, either globe, gate, or butterfly valve instead of replacing the same by complete anti cavitation valve, specially that the perforated plates are used in the pipeline industry as pressure and flow conditioner to reconfigure the fluid energy in the pipeline when used to correct the fluid flow profile and pressure profile in piping systems, by dissipation of the fluid energy in the said valves.
3. Summary of the Invention The fluids under high pressure in control valves or other throttling devices are subjected to cavitation, flashing and noise problems which causes erosion of valve's trim and body.
Cavitation occurs if the static pressure of the flowing liquid tends to decrease to a value less than the fluid vapor pressure. At this point, the flow is broken by the formation of vapor bubbles, the vapor bubbles revert back to liquid. This two-stage transformation is defined as cavitation. The collapse of vapor bubbles can produce very high localized pressure which causes rapid erosion of valve trim under high pressure drop conditions, it is therefore, necessary to prevent the high differential pressure a nd sudden p ressu re drop condition encounter the valve. The inlet to outlet valve pressure to be reduced gradually, thus avoiding sudden pressure drop at valve vena contracta (restriction). Both art anti-cavitation type valves dissipate the energy of the fluid passing through the valve-trim by changing the pressure and flow profile of the fluid inside the valve. There are numerous perforated plates used in industry some patented, some public domain, others commercial, but no patent restriction plates device discuss a solution for cavitation problem in conjunction with the conventional control valve to condition the upstream severe process service upstream the valve to provide a normal differential pressure across the valve to eliminate cavitation problem.
The present device is compact stainless steel structure incorporated two integral perforated plates, upstream and downstream installed at valve inlet flange, the two plates act to dissipate the fluid energy in changing fluid pressure profile and fluid velocity profile - will be explained hereinafter- The restriction plates provide serpentine paths to the fluid severe condition flow passing through the plates which are designed for maximum process flow rate capacity with extra 25-33%
flow capacity to provide sufficient valve travel, thereby the valve run in normal operation without re-calibration and the static inlet line pressure is reduced gradually to change the fluid pressure and velocity profile, and cavitation is avoided by not permitting the pressure to fall below the vapor pressure, thereby eliminating bubble formation, subsequent collapse, and transformation of liquid faces. The present invention invention takes in consideration a compact insertion type device with maximum length of 64-76mm (2.5-3.0 inch) easily inserted in valve inlet flange suitable for installation in all pipeline RE raised face and RTJ ring type joint flanges for conditioning upstream severe process condition of valves, fluid transfer systems and lines where a potentially high pressure exists and may cause cavitation, erosion and severe noise level. Another object of the invention is to provide economical low cost solution, simple in construction, with minimum material cost and manpower installation. Another object of the invention is to provide new and improved means for controlling both high velocity and pressure of a flowing fluid in one compact device by dividing and controlling the high pressure fluid into a plurality of smaller streams in such away to eliminate problems of erosion, control, noise and fatigue failure caused by high velocity. Other object of the present invention is to dissipate the energy of the high pressure flowing fluid without increasing velocity and shock wave reaction, therefore the device can be used also for process equipment, transfer lines system, and for process piping system where damage is expected due to high fluid velocity, cavitation or erosion. Still another object of the invention is to control and limit fluid gas pressure in gas distribution lines where the high noise level and pressure is required to be reduced.

4. Brief Description of the Drawings Fig. 1. illustrate the device with its upstream and downstream perforated plates Fig.-01(a): illustrate the perforated pressure conditioner plate Fig.-01(b): illustrate the perforated flow conditioner plate Fig.-02: illustrate the conventional valve with upstream device and valve differential pressure Fig.-03: illustrate the installation of the compact device in valve inlet flange Fig.-04: shows installation of the device into raised face flange Table.-01: shows Sigma index calculations with examples of valve pressure differential Table.-02: shows examples of pressure restriction plate differential pressures against Sigma index Table.-03: shows examples of the restriction plate sizing for plate differential pressure and maximum flow capacity.

5. Detailed Description Referring now to FIG.-01, the apparatus comprises of following construction parts:
(1) Upstream pressure restriction conditioner plate (2) Downstream flow restriction conditioner plate (3) Ring maximum thickness 3.0 inch with flow passage The present invention is a paddle type steel device comprises two perforated restriction plates (1) and (2) whereas both plates are attached to the ring (3), as shown in FIG.01 Both pressure and flow conditioners plates acts to dissipate fluid energy to provide a normal conditioned process fluid to the conventional control valve inlet. The inlet perforated restriction plate (1) has array of one size holes (4) and the outlet restriction plate (2) has smaller size perforations (5).
The plates are separated from each other by insufficient flow run flow passage to avoid pressure recovery of fluid exit the first plate. In a first embodiment, the pressure conditioner plate (1), FIG.-01(a) is made in arrays of one common size perforations (4) which causes the fluid flow to be reconfigured where the liquid pressure energy is dissipated by changing the fluid pressure profile. The second perforated plate (2), FIG.01(b) keeps the first plate outlet fluid flow pattern mismatching with the first plate's flow pattern to create plurality of different paths and irregularities in the flow profile through the plate smaller size holes (5) to dissipate the velocity energy and acoustic noise level generated by the first plate's holes before entering the valve for protection of the valve trim from direct fluid impingement impact. The difference in the diameters of the hole plates between 40-50% of the large hole diameter.
In a second embodiment referring to FIG.-02, the device installed upstream of the control valve (6) at valve inlet flange designed to create a predetermined differential pressure (7) to reduce the inlet pressure so that a normal differential pressure across the valve (8) can be achieved and consequently avoid transformation of the liquid to vapor and eliminate the direct impingement of the liquid on valve trim and body, means that the reduced outlet pressure (P2) is the inlet pressure to the valve, and the new differential pressure across the valve (8) will satisfy the condition of eliminating the cavitation effect, since the outlet pressure will be above the liquid vapor pressure and the control valve is prepared to operate in a more normal process condition.
Referring now to Table-01, the cavitation can be measured and controlled by calculating the cavitation index, called Sigma (a) which is = P1-Pv/P1-P2, where Pv is the liquid vapor pressure and (P1-P2) is the differential pressure across the valve (AP). Higher the Sigma index value means lower value of the differential pressure across the valve, and lower cavitation effect on the valve, which further means that the main reason of cavitation is the high pressure across the valve, therefore the first restriction plate is used to achieve lower outlet pressure of the plate which is the inlet pressure to the valve (6), resulted in low differential pressure (8) across the valve.
As a result in the example shown in Table-01 for different static inlet pressure and valve differential pressure (AP) , the valve with a cavitation index of 1.7 and above, means that there is no cavitation exist, while the valve under higher differential pressure, with a cavitation index of 1.51 to 1.0 are subjected to severe cavitation, whereas valves with a cavitation index of 1.51 -1.69, means that the valve is under cavitation impact, the valve trim should be replaced by harder material, the higher the hardness, the greater the resistance, such material as Hestalloy C, 321 or 347 stainless steel, Monel, Tungsten, or stellated face plug and seat, material of which should match the type of fluid whether corrosive or not.
Referring to Table-02, the example of different high static inlet pressures shows that the first restriction plate should be sized to absorb a differential pressure of ¨for example 300psi- in order to achieve a cavitation index of 1.7 and above to run the valve under normal process condition.
Table.-03 shows that, in order to achieve the above requirement, the said plate should be checked and calculated to ensure handling different inlet static pressures along with high cavitation index. The plate Beta ratio (p) and bore diameter are calculated to obtain the plate opening area which should handle the process condition shown in the example taking in consideration that the said area must handle the valve maximum flow rate capacity with extra flow capacity of 25-33%
of valve rated capacity to provide sufficient valve's plug travel.
The restriction plate (2) bore diameter and bore area are sized based on a single bore concentric plate, with the calculated bore area is equal to the total perforations (holes) area, and the number of the plate's holes equal to the bore area divided by the area of the plate hole. Further embodiment, the fluid stream flow path passing through the first perforated plate (1) is subdivided by the perforations. The extremely high pressure fluid exit the said plate generates noise and high jet velocity due to harmonic interaction between the hole downstream of the plate. As fluid exit through each hole (4), the fluid accelerates due to the restriction of the inside walls of the said holes and initiates a high speed stream fluid, and expand to meet the downstream flow conditions.
The fluid jets downstream of the first plate is detrimental aspect of valve trim and body internals if direct impingement of the liquid high velocity energy - exit the holes of first plate -is subjected to the valve. The high fluid velocity and severe noise generation of the perforated plate should be taken in consideration in perforated restriction plates, therefore there is a need for a second perforated plate (2) with array of smaller diameter perforation (5) in opposite of the first plate's holes axial direction in which the jet velocity vortices are disturbed and the velocity energy is conditioned due to the change of the flow pattern and subdividing the flowing fluid streams exit the first plate (1) means that the fluid encounters the second plate - which act as baffles - deflected the said stream to each side and flows between adjacent holes toward the next row of holes, and flow through passages that create a high energy loss and pressure drop due to irregular and opposite stream passages directions. This process continues, and the pressure is reduced by friction with the walls and by the frequent change in directions which finally dissipate the fluid high velocity energy and consequently reduces the noise level before entering the valve without shock waves since the void between the two restriction plates act as packed muffler. A previous attempts to silence perforated plate noise have been only partly successful, U.S. Patent Application 20040055816 by James Gallagher et al, published in March 25, 2004, an apparatus for filtering ultrasonic noise within a fluid flow system, the method attenuates the noise propagating between a noise source and a reference point in the flow stream (wherein the reference point and the noise source are positioned in the flow stream in direct acoustic line of sight relation). The method includes positioning an absorbent element in the flow stream between the noise source and the reference point.
Referring to FIG.-03, The device is sandwiched between upstream valve flange faces without pipe cutting, or welding, with new flange gaskets, the conditioner plates type and pressure rating shall be in accordance with flange type either RF raised f-ace or RTJ ring. type join+, flange, the maximum valve flange faces separation distance required to insert the device is 2.5-3.0 inch, this can be achieved by simple pipe fitter's tools, however attention must be paid to ensuring that the flange faces are parallel to the ring on both sides, and not angled. The new flange sp,reading use unique technology at present for safe spreading flange faces a distance of 5.5 - 8.5 inch. The restriction plates, pressure rating, material, and dimensions in accordance with the standard specifications of AGA., ISA., ASME., API., and ISO.

6. Patent Citation Citation No. Title Names Date line No.
US20060096650 Non-linear noise suppressor Sawchuk Blaine 0 May 11,2006 28-for perforated plate flow conditioner use perforated plates installed in pipeline in front of the flow meter cause the fluid flow to be reconfigured U.S.5,762,107 Flow conditioner Den Norske Stats Jun 9,1998 3-4 The conditioner comprises a plate arranged perpendicular to the flow having apertures which are located so as to distribute the flow radially US3,513,864 High pressure fluid control means Self Richard E May 26,1970 Using disks inside the valve, where pressure fluid is dissipated by subdivision in a skeletal disk baffle grid assembly into a plurality of tortuous courses US 2021079 A Restricted flow device Crosley Radio Corp. Nov 12,1935 3-4 control the flow of liquefied refrigerant from the condenser in a refrigerating device to the evaporator US2007110712 Non-linear noise suppressor Blaine D.Sawchuk Mar 13, 2008 1-3 A flow conditioner for use in a pipeline to be used in conjunction with a flow meter. The flow conditioner uses alternating hole sizes to reduce ultrasonic noise produced by high flow rates US5819803A Fluid pressure reduction device Kim W. Lebo Oct 13, 1998 A fluid pressure reduction device includes a plurality of flow resistance modules to provide tortuous flow paths within the valve by using disks.
US3722854A Valve with perforated ribbon Grove Valves Mar 27,1973 silencing element coiled ribbon of sheet material wrapped into a plurality of layers inside the valve resultant high energy loss greatly reduces the average velocity and, hence, the sound level US3856049A Multiple stage restrictor Leslie Co Dec 24,1974 1-3 A multiple stage restrictor is characterized by a plurality of stacked plates inside a valve to relatively decreases velocity by restricting passages through which the fluid flows US5390896A Energy loss device Control Components Inc. Feb 21,1995 2-4 A valve utilizing the energy loss by series of Stacks for fluid flow paths and plurality of members joined together for energy loss US4221037A Method for manufacturing a fluid Copes-Vulcan, Inc. Sep 9,1980 control device with disc-type flow restrictor Valve trim includes a novel form of flow restrictor, which serves to limit flow velocity and causes fluid pressure to be reduced in a sufficient number US3514074A High energy loss fluid control Self Richard E May 26,1970 2-15 velocity control of high pressure flowing fluids and attain energy losses or high pressure drop by using passage disks within the valve

Claims (6)

l claim:

1. Use of an anti- cavitation conditioner compact paddle type device upstream of a control valve, in an existing fluid system, said device comprising two perforated restriction plates installed on each side of a ring" arranged to be inserted and fit between an upstream valve flange, in accordance to the flange type and dimensions, and installed upstream of conventional control valves facing fluid inlet severe process condition to change fluid pressure and flow profile and dissipating fluid energy by a plurality of different paths formed in said first and second plates perforations, whereby when flowing fluid passes through said plurality of perforations, its flow pressure will be reduced, eliminating cavitation effect, erosion in liquid valves and generated noise in gas valves, wherein the first plate is a perforated pressure conditioner restriction plate for changing the fluid pressure profile, and the second plate is a perforated flow conditioner restriction plate for changing the fluid flow profile.

2. Use of an anti-cavitation device as defined in claim 1 wherein device design is customized for each valve size and fluid process service condition passing through the valve.

3. Use of an anti-cavitation device as defined in claim 1 wherein total holes area of each restriction plate is calculated to pass maximum fluid capacity through the valve with reduced differential pressure across the valve calculated under valve process condition to obtain required cavitation index.

4. Use of an anti-cavitation device as defined in claim 1 wherein the throttling passages of the first plate are offset in the flow direction from the passages of the second plate to provide tortuous flow of fluid.

5. Use of an anti-cavitation device as defined in claim 1 wherein said device restriction plates including said perforations are designed to achieve minimum cavitation index of 1.7, wherein said index is inversely proportional with the new differential pressure across the valve created by said restriction orifice plates.

6. Use of an anti-cavitation device as defined in claim 1 characterized in such away said device is inserted into predetermined size, type, and pressure rating of valve upstream flange, use no pipe cutting or welding for installation.