Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2003-03-27
2004-08-31
Fox, John (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
Reexamination Certificate
active
06782920
ABSTRACT:
This invention relates to a fluid flow control device. It may be used to control the flow of liquids or gases and may, for example, be used to provide velocity control of high pressure flowing fluids.
Devices of this general type are sometimes known as variable fluid restrictor control valves, and are exemplified by Self U.S. Pat. Nos. 3,451,404 and 3,514,074 which have frictional passageways, and by Self U.S. Pat. No. 3,513,864 which has multiple abrupt, angular turn passageways.
In the handling of flowing high pressure fluids, it has been customary to utilise orifice means having a high velocity short throat section to attain energy losses or high pressure drops. If the fluid is in a liquid state and liable to flash, that is, vaporise or turn to a gaseous condition on the downstream side of the orifice or valve opening, it may condense implosively and induce damaging shock waves, cause erosion, and the like. Also, as the velocity of the fluid in the valve exceeds the velocity of the fluid in the line, several disturbing reactions occur.
A most serious problem is rapid erosion of the valve surfaces by direct impingement of the liquid and any foreign particle suspended therein. Additional erosion results from cavitation. Cavitation may be defined as the high speed implosion of vapour against those internal parts of the valve controlling flow (the valve trim) and the valve body.
In addition to the severe problems resulting from erosion, the increased velocity also causes the flow characteristics of the valve to become unpredictable and erratic.
Other problems created by the high fluid velocity in the valve are severe noise generation, trim fatigue and possible degradation of flowing fluid materials such, for example, as polymers.
Fluid-borne noise downstream of control valves is often very high. If not treated or contained within the pipe, this noise can result in sound pressure levels of 110 to 170 dB about 0.9 m (three feet) from the valve exit. Sound sources of this magnitude are hazardous to personnel and frequently result in complaints from local residents.
Mufflers and silencers can typically only attenuate fluid-borne noise 20 to 30 dB. Therefore, only partial success has been achieved with them in obtaining desired sound pressure levels. Furthermore, a typical path treatment system i.e., the muffler, lagging support structure etc. is very cumbersome and expensive, often, the total cost of path treatment for noise can exceed the valve cost many times over.
In order to overcome or ameliorate the above problems, there have been introduced devices which effect energy losses in high pressure fluids without increasing velocity and shock wave reaction. This is achieved by subdividing the flow into a plurality of small, long passageways with abrupt turns creating friction and pressure drop in the fluid, thus avoiding damage and erosion in the equipment. Such a device is disclosed, for example, in U.S. Pat. No. Re 32,197.
There, the passageways are provided in an annular stack of separate members having abutting faces enclosing a plurality of individual passageway grooves. The grooves are angular between the inlet and outlet of the stack to turn the fluid and to provide a substantially longer flow length than between the inlet and outlet ends of the stack. The stack is mounted in the fluid passage of a valve housing and a valve plug movable within the annular structure controls the number of passageways in the stack through which the fluid can flow.
A modified device of this type is disclosed in GB-A-2,273,579 in which at least one passageway in the stack of members of discs includes a void between the inlet and outlet region of the disc, the void expanding the cross-sectional area of the energy loss passageway.
In our U.S. Pat. No. 5,687,763 we have described and claimed a structure having improved energy loss passageways, namely a fluid flow control device comprising a plurality of pairs of annular discs forming a rigid structure which incorporates a series of substantially radial passageways for fluid flow. Each disc of said pair has two major faces and passageways which extend completely through said disc between said major faces but extend only partially in a radial direction. The discs of each pair are substantially identical and are aligned with one another with a major face of one disc in direct abutment with a major face of the other disc. The passageways in said one disc interconnect with the passageways in the other disc of the pair so as to provide for fluid flow through the pair of substantially identical discs.
It is an object of the present invention to make a further improved flow control device and parts for use therein. It is also a preferred object of the present invention to provide a fluid control device in which erosion of surfaces, may be reduced.
Accordingly, in one aspect, the present invention provides a stack of annular discs for a flow control device, the discs forming a structure which incorporates a series of passageways for fluid flow, adjacent discs having abutting major surfaces to define said passageways therebetweeen, some at least of the discs each having a passageway extending from its outer perimeter to its inner perimeter, said passageway being formed of a depth to extend only partially into the thickness of the disc, a portion at least of the length of the passageway being curved, the curved portion of the passageway commencing at one of said perimeters and/or a portion at least of the length of the passageway being linear, the linear portion of said passageway commencing at the other of said perimeters.
Preferably, the passageways are grooves or channels formed in at least one of two major faces of a disc and being closed other than at their ends by an abutting major face of an adjacent disc.
In another aspect, the present invention provides an annular disc for incorporation in a fluid flow control device, which device comprises a stack of annular discs, the disc having an inner and an outer perimeter and at least one groove passageway formed in one of its major faces, a portion at least of the length of the passageway being curved, the curved portion of the passageway commencing at one of said perimeters and/or a portion at least of the length of the passageway being linear, the linear portion of the passageway commencing at the other of said perimeters.
The plurality of discs forms a stack in which central apertures of the discs define a central passageway for a reciprocatable plug. The fluid flow passageways formed by the discs lead into or lead from the central passageway depending on the direction of fluid flow through the stack. The plug is positionable in the central passageway to completely close off fluid flow at one extreme and to allow fluid flow through all the disc passageways at the other extreme. The position of the plug between these extremes may be adjusted to allow the desired flow rate between fully off and fully on, i.e. to allow flow through the passageways of a lesser or greater number of discs, as required.
In another aspect, the present invention provides a fluid flow control device incorporating a stack of annular discs, central apertures of the annular discs forming a central passageway extending longitudinally of the stack, a plug reciprocably movable within the central passageway and an actuator to move the plug as required to control fluid flow through the device from a fully closed through partially open positions to a fully open position, adjacent discs having abutting major faces defining at least one fluid passageway extending between inner and outer perimeters of the discs, said passageway being curved for at least a portion of its length commencing at one of said perimeters and/or being linear for at least a portion of its length commencing at the other of said perimeters.
In one embodiment, flow through the fluid passageways across the discs is from the outer perimeters to the inner perimeters of the discs, i.e. into the central passageway. The central passageway is then connected to an outlet for the
Control Components Inc.
Fox John
Stetina Brunda Garred & Brucker
LandOfFree
Fluid flow control device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluid flow control device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid flow control device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3333147