Abstrict An insertion vortex flow meter for measuring a flow rate of a process
fluid in a pipe has a mounting assembly, a shedding bar and a sensor
assembly. The mounting assembly is attached to a surface of the
pipe adjacent an opening in a side wall of the pipe. The shedding
bar is inserted through the opening and extends an entire diameter
of the pipe. The shedding bar is held in place by a compression
force exerted by the sensor assembly on a proximal end of the shedding
bar, such that the shedding bar is held by the compressive force
between the sensor assembly and an opposing side wall of the pipe.
The sensor assembly is adapted to measure motion of a pivoting element
corresponding to vortices in the process fluid caused by the shedding
bar. The sensor assembly adapted to produce an output indicative
of the volumetric flow rate based on the frequency of the measured
motion.
Claims What is claimed is:
1. An insertion vortex flow meter for measuring a flow rate of
a process fluid in a pipe, comprising: a conduit having a wall surrounding
a bore for carrying a fluid along a bore axis, the wall having an
opening extending entirely through the wall; a shedding bar disposed
within the conduit to induce disturbances in the process fluid,
the shedding bar extending from the opening into the bore and to
an opposing wall of the conduit; a pressure bearing element coupled
to the shedding bar and adapted to move in response to the disturbances
in the fluid at a frequency indicative of the flow; and a mounting
apparatus disposed adjacent the opening in the conduit, the mounting
apparatus coupled to the conduit and adapted to secure the shedding
bar and the pressure bearing element in place.
2. The insertion vortex flow meter of claim 1 and further comprising:
a reinforcement element disposed on the opposing side wall of the
pipe and sized to interface with a distal end of the shedding bar.
3. The insertion vortex flow meter of claim 1 wherein the mounting
apparatus further comprises: a mounting collar fixedly attached
to the surface of the pipe; and a mounting cover releasably attached
to the mounting collar.
4. The insertion vortex flow meter of claim 3 wherein the mounting
collar has threaded openings and the mounting cover has fastener
openings, and wherein the mounting cover is releasably attached
to the mounting collar with threaded fasteners extending through
the fastener openings and into the threaded openings of the mounting
collar.
5. The insertion vortex flow meter of claim 1 further comprising:
a sensor coupled to the pressure bearing element and adapted to
sense motion of the pressure bearing element.
6. The insertion vortex flow meter of claim 5 wherein the sensor
is adapted to generate an output based on the sensed motion, the
output being indicative of a volumetric flow rate.
7. An averaging insertion vortex flow meter for measuring fluid
flow, comprising: a conduit having a wall surrounding a bore for
carrying a fluid along a bore axis, the wall having an opening extending
entirely through the wall; a shedding bar extending from the opening
into the bore, the shedding bar contacting an opposing wall of the
conduit at a distal end, the shedding bar for causing disturbances
in the fluid; a pressure bearing element extending from the opening
and adapted to move in response to the disturbances in the fluid
at a frequency indicative of the flow; and a mounting apparatus
disposed adjacent the opening in the conduit, the mounting apparatus
for attaching to the conduit and for holding the shedding bar and
the pressure bearing element in place.
8. The flow meter of claim 7 wherein the mounting apparatus exerts
a compressive force on the shedding bar to hold the shedding bar
in position against the opposing wall.
9. The flow meter of claim 7 wherein the mounting apparatus comprises:
a cylindrical mounting collar sized to fit the opening, the mounting
collar having an end that is contoured to match a curvature of the
conduit; and a mounting cover sized to fit over the mounting collar
and adapted to attach to the mounting cover.
10. The flow meter of claim 7 wherein the mounting apparatus is
welded to the conduit.
11. The flow meter of claim 7 and further comprising: a sensing
device coupled to the pressure bearing element, the sensing device
adapted to sense motion of the pressure bearing element.
12. The flow meter of claim 11 wherein a frequency of the sensed
motion is a function of a volumetric flow rate of the fluid flow.
13. The flow meter of claim 7 and further comprising: a sensor
coupled to the pressure bearing member for sensing motion of the
pressure bearing member and for providing an output indicative of
the flow.
14. The flow meter of claim 7 and further comprising: processing
circuitry for calculating a flow rate of a fluid based on the output
of the sensor.
15. The flow meter of claim 7 wherein the shedding bar, the pressure
bearing element, and a sensor housing are cast as a single solid
unit.
16. The flow meter of claim 7 and further comprising: a temperature
sensor close-coupled to a surface of the pipe for measuring a fluid
temperature.
17. The flow meter of claim 16 and further comprising: processing
circuitry for calculating a flow rate of a fluid based on an output
of a sensor coupled to the pressure bearing element and based on
a sensed temperature measured by the temperature sensor.
18. The flow meter of claim 7 and further comprising: a pressure
sensor close-coupled to a surface of the pipe for measuring a fluid
pressure.
19. A flow meter according to claim 7 and further comprising: a
reinforcing element positioned on the opposing wall of the conduit
and sized to receive the distal end of the shedding bar.
20. The flow meter of claim 18 wherein the reinforcing element
is a recess on a surface of the opposing wall.
21. A method of installing a vortex flow meter comprising: machining
a hole in a wall of a pipe, the pipe for carrying a fluid; attaching
a mounting assembly to the wall of the pipe adjacent to the hole;
inserting a vortex flow meter assembly into the hole in the pipe;
and releasably attaching the vortex flow meter assembly to the mounting
assembly to fix the assembly in place within the pipe.
22. The method of claim 21 wherein the step of attaching comprises:
welding the mounting assembly to the wall of the pipe.
23. The method of claim 21 wherein the vortex flow meter assembly
comprises: a shedding bar sized to fit the hole and having a length
that is approximately equal to an inside diameter of the pipe, the
shedding bar having a cavity machined in a proximal end; a pressure
bearing element having a pivoting element and a cap, the pivoting
element sized to fit within the cavity of the shedding bar; and
a transducer physically connected to the pressure bearing element,
the transducer for sensing a motion of the pressure bearing element
and for providing an output indicative of the flow according to
the sensed motion.
24. The method of claim 21 wherein the step of inserting comprises:
inserting a pivoting element of a pressure pressure bearing element
into a cavity on a shedding bar; connecting the pivoting element
to a sensor; installing the shedding bar through the hole and into
the conduit such that a distal end of the shedding bar is in contact
with an opposing wall of the conduit; and tightening a mounting
cover onto the mounting assembly to hold the shedding bar and the
pressure bearing element in place within the pipe.
25. The method of claim 24 wherein the mounting cover imparts a
compressive force on the shedding bar to hold the shedding bar against
the opposing wall.
26. The method of claim 21 wherein the step of inserting comprises:
installing the vortex flow meter through the hole in the pipe, such
that a distal end of a shedding bar of the vortex flow meter contacts
an opposing wall of the pipe.
27. A component assembly of a vortex flow meter for measuring a
flow of a fluid within a conduit, comprising: a mounting structure
attached to a surface of the conduit adjacent a hole extending through
a wall of the conduit; and a vortex flow meter attached to the mounting
structure comprising: a shedding bar extending approximately a full
diameter of the conduit; a pressure bearing element having a pivoting
member and a cap attached to the pivoting member, the pivoting moving
in response to disturbances within the fluid at a frequency indicative
of the flow; and a pressure sensor assembly having a sensor physically
connected to the pressure bearing element for sensing the motion
of the pivoting member; wherein the mounting structure holds the
vortex flow meter in place during operation.
28. The component assembly of claim 27 wherein the mounting structure
comprises: a mounting collar sized to fit around the hole, the mounting
structure having a substantially cylindrical shape, the mounting
collar provided with openings sized to receive a fastener; a cover
sized to fit over the mounting collar, the cover having fastener
openings corresponding to the openings on the mounting collar; and
fasteners for tightening the cover onto the mounting collar.
29. The component assembly of claim 27 wherein a connection between
the sensor and the pressure bearing element is mechanical.
30. The component assembly of claim 27 wherein the mounting structure
includes a mounting collar and a cover, and further comprising:
a spacer sized to fit at least partially into the mounting collar
such that the cover rests on the spacer when the cover is placed
over the mounting collar.
Description BACKGROUND OF THE INVENTION
[0001] The present invention relates to flow meters such as vortex
shedding meters or swirl meters, which are responsive to a fluid
flow. More particularly, the present invention relates to an insertion
vortex meter for use with large diameter pipes.
[0002] Generally, flow meters sense the flow of liquids or gases
in conduits and produce a signal representative of the flow. One
type of flow meter for measuring fluid flow is called a vortex flow
meter. The vortex flow meter generally measures the fluid flow by
detecting approximately sinusoidal pressure changes created by a
moving vortex within the fluid flow.
[0003] Generally, the vortex flow meter includes an obstacle known
alternatively as a shedding bar, bluff body, or vortex generator.
The shedding bar is inserted into the fluid flow causing instability
of the flow field. Specifically, the shedding bar splits the flow
into two paths around the shedding bar, causing vortices to shed
from alternate sides of the object at a frequency linearly proportional
to velocity of the flow.
[0004] As the bar splits the fluid flow, vortices are created in
the fluid flow. These vortices are sometimes referred to as shedding
vortices. The shedding vortices produce an alternating differential
pressure across the shedding bar at a shedding frequency. This differential
pressure is converted into an electrical signal by a piezo-electric
sensor. The frequency of the differential pressure or electrical
signal is proportional to the velocity of the fluid flow.
[0005] In general, vortex meters for larger size fluid conduits
tend to be less economical than differential pressure meters or
insertion-type meters, in part, because of the large amount of steel
or other materials required to produce the standard vortex meter
body. In particular, conventional vortex meters are typically sold
as a pre-fabricated unit having a pipe section with a flange on
each end and a vortex flow meter centered within the pipe section.
Such pre-fabricated sections are expensive to produce, because they
contain a great deal of metal. Additionally, such sections are expensive
to ship because of their weight. Finally, conventional flow meters
require that the flow meter be installed between pipes, requiring
either that the pipe be cut to insert the flow meter or that the
flow meter be installed at the time of the original installation.
[0006] There is a need for a vortex-type flow meter that can be
produced economically and used with large diameter pipes. There
is also a need for a vortex-type flow meter that can be installed
into an existing pipe system without having necessarily to stop
the fluid flowing within the pipe.
SUMMARY OF THE INVENTION
[0007] An insertion vortex flow meter for measuring a flow rate
of a process fluid in a pipe includes a mounting assembly, a shedding
bar and a sensor assembly. The mounting assembly is attached to
a surface of the pipe adjacent an opening in a side wall of the
pipe. The shedding bar is inserted through the opening and extends
an entire diameter of the pipe. The sensor assembly is electrically
connected to the shedding bar and releasably attached to the pipe
via the mounting assembly. Installation of the insertion vortex
flow meter involves drilling a hole in a sidewall of a pipe, fixing
a mounting assembly to the pipe adjacent the hole, inserting the
shedding bar through the hole, and attaching the sensor assembly
to the mounting assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a sectional view through a pipe carrying a fluid
flow and having a vortex flow meter using a bluff body or shedding
bar made according to the present invention;
[0009] FIG. 2 is a sectional view taken along line 2-2 of FIG.
1;
[0010] FIG. 3 is an exploded view of the vortex flow meter of the
present invention;
[0011] FIG. 4 is a simplified flow diagram of the process of installing
the vortex flow meter of FIG. 1;
[0012] FIGS. 5A-5D illustrate different embodiments showing top
plan views of various configurations of the vortex flow meter assembly
in situ;
[0013] FIGS. 6A and 6B illustrate sectional views taken along lines
2-2 in FIG. 1 illustrating a reinforcement element on an inside
wall of the pipe opposite the insertion opening; and
[0014] FIGS. 7-9D illustrate alternative embodiments of the reinforcement
element for supporting the shedding bar of the vortex flow meter
assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] The present invention is directed to an averaging insertion
vortex meter, which solves the problem of high cost by using an
insertion technique. In the present invention, the shedding bar
of the vortex meter extends across the entire pipe, resulting in
an averaging effect. Typical insertion meters, as installed, are
inaccurate because they extrapolate a single point velocity measurement
into flow over an entire pipe. In theory this works great, but in
practice, single point velocity measurements are subject to hundreds
of problems that more than double the applied uncertainty of these
types of meters. By having a meter that extends across the entire
pipe, the insertion-type vortex meter is as accurate as a standard
vortex meter in a tradition meter body.
[0016] FIG. 1 illustrates an embodiment of a vortex flow meter
of the present invention. Generally, the vortex flow meter assembly
10 includes a vortex sensor 12 that has appropriate mechanical and
electrical elements that sense vortices in a fluid flow within a
conduit 14. The vortex sensor 12 is operably or electrically coupled
(such as by leads 16) to an electronic circuit 18 (shown in phantom).
The electronic circuit 18 may be capable of producing both a 4-20
mA current on a current loop indicative of the flow, as well as
a square wave output (F.sub.out) having a frequency proportional
to the fluid flow. Alternatively, the electronic circuit 18 may
include a wireless transducer (shown in FIG. 5D) for transmitting
a signal representative of the flow wirelessly to a control room.
[0017] Generally, the vortex flow meter assembly 10 of the present
invention includes a housing 20 having a mounting collar 22 and
a cover 24 a vortex generator, bluff body or shedding bar 26 and
a pressure bearing element 28 (shown in FIG. 2). The pressure bearing
element 28 is sometimes referred to as a "pivoting element".
In general, the pressure bearing element 28 moves in response to
the fluctuating pressures of the fluid vortices caused by the shedding
bar 26.
[0018] The sensor 12 is coupled to the pressure bearing element
28 preferably by attachment to a post (shown in FIG. 3 and indicated
by reference numeral 29). The sensor 12 senses the motion of the
pressure bearing element 28 via the post 29 and provides an output
indicative of the motion. Since the frequency of the motion is a
function of the volumetric flow rate, the output is also indicative
of the flow.
[0019] Generally, the housing 20 is mounted to a pipe 14 and the
shedding bar 26 is positioned through an opening in a wall of the
pipe 14 and into a fluid flow. When fluid flows past the shedding
bar 26 the shedding bar 26 splits the fluid into two flow paths,
creating shedding vortices that have a frequency indicative of the
flow rate. The vortices cause the pressure bearing element 28 to
move with the frequency of the vortices. The sensing device 12 or
transducer of the flow meter 10 senses the motion of the pressure
bearing element 28 associated with the shedding vortices.
[0020] In FIG. 1 the vortex flow meter assembly 10 is shown in
situ and mounted to a pipe 14. The flow meter assembly 10 has a
shedding bar 26 inserted through an opening (shown in FIG. 3) in
a wall of the pipe 14 and extending the entire width of the inner
diameter (d) of the pipe 14. The flow meter assembly 10 includes
a mounting collar 22 which is welded or otherwise attached to the
outer wall 30 of the pipe 14 around an opening (shown in FIG. 3).
A pressure bearing element 28 (shown in FIG. 2) is positioned in
a cavity 32 in a proximal end 34 of the shedding bar 26. The distal
end 36 of the shedding bar 26 is in contact with the inside wall
of the pipe 14 on the side of the pipe 14 opposite the opening.
[0021] In one embodiment, the sensing device 12 is mechanically
connected with the pressure bearing element 28. Leads 16 may extend
from the sensing device 12 out from the mounting cover 24 and may
be connected to processing electronics or to an electronic circuit
18.
[0022] The mounting cover 24 is positioned over the mounting collar
22 and fasteners 38 are used to fix the mounting cover 24 into place.
A spacer element 40 may be used to hold a sensor housing for the
sensing device 12 which is disposed within the mounting collar
22 in position when the mounting cover 24 is tightened over the
mounting collar 22.
[0023] Generally, the mounting collar 22 surrounds the opening
in the wall of the pipe 14. The pipe end of the mounting collar
22 generally has a surface that is contoured to conform to the curvature
of the pipe 14. If the mounting collar 22 extends into the opening,
rather than around the opening, the surface may be contoured to
conform to the curvature of the inside diameter of the pipe 14.
Generally, the mounting collar 22 is welded to the outside surface
of the pipe 14.
[0024] On an end of the mounting collar 22 opposing the pipe 14
fastener openings (shown in FIG. 3) are provided for receiving the
fasteners 38. In this way, the cover 24 can be releasably mounted
to the mounting collar 22.
[0025] In general, the sensing device 12 is coupled to a pressure
bearing component 28 which is inserted in a cavity 32 in the proximal
end 34 of the shedding bar 26. The sensing device 12 senses motion
of the pressure bearing element 28 relative to the shedding bar
26. The pressure bearing element 28 moves relative to the frequency
of the flow vortices formed on opposite sides of the bar 26 and
the sensing device 12 measures the motion of the pressure bearing
element. The sensing device 12 generates an output that is indicative
of the motion of the pressure bearing element, and which is related
to the flow of the fluid.
[0026] The shedding bar or bluff body may be of any known shape.
A preferred embodiment of the shedding bar is taught in U.S. Pat.
No. 4464939 which is incorporated herein by reference in its
entirety.
[0027] FIG. 2 shows a cross-sectional side view of the vortex flow
meter assembly 10 of the present invention in situ. As shown, the
shedding bar 26 extends the entire length of the inner diameter
(d) of the pipe 14. A cavity 32 machined into the proximal end 34
of the shedding bar 26 receives the pressure bearing element 28.
A mounting collar 22 is fixed to the outside surface 30 of the pipe
14. The sensing element 12 and a portion of the cap 42 are positioned
within the mounting collar 22. A spacer 40 is shown between the
sensing element 12 and the mounting cover 24. The mounting cover
24 is positioned on top of the spacer 40 and over the mounting collar
22 and attached with fasteners 38 to the mounting collar 22.
[0028] In general, the mounting collar 22 holds the sensor housing
(shown in FIG. 3 and indicated by reference numeral 46) and the
shedding bar 26 in position via pressure applied by the mounting
cover 24 through tightening the fasteners 38.
[0029] In general, the mounting collar 22 in the embodiment shown
is a cylindrical element having an outer diameter and an inner diameter.
The inner diameter is sized to receive the spacer 40 the sensor
12 and the cap 42 of the pressure bearing element 28. Additionally,
the shedding bar 26 is generally inserted into the mounting collar
22 (which is already attached to the pipe 14) and through an opening
in the pipe 14.
[0030] It will be understood by workers skilled in the art that
the present invention allows for the attachment of a vortex flow
meter assembly 10 without requiring an entire pipe section with
flange elements for making the necessary attachments. In general,
it will be understood that the component elements that make up the
flow meter assembly 10 can be produced and sold as individual components
or as a complete assembly for insertion into an opening in the pipe
14. An end user can drill the opening, attach the mount collar 22
and insert the shedding bar 26 with the attached sensor 12 into
the mount collar 22 and through the opening. It will also be appreciated
by a worker skilled in the art that the flow meter assembly 10 of
the present invention can be attached to the pipe via any number
of techniques and/or attachment means. For example, the flow meter
assembly of an embodiment of the present invention can be mounted
to the pipe using the "insert/retract mechanism" described
in U.S. Pat. No. 4633713 which is incorporated herein by reference.
Additionally, an embodiment of the present invention can be mounted
to the pipe using the method and apparatus of U.S. Pat. No. 4717159
which is incorporated herein by reference. One possible embodiment
of a method of installation is described with respect to FIG. 4.
[0031] Referring now to FIG. 3 an embodiment of the flow meter
assembly 10 is shown an exploded view. As previously discussed,
an opening 44 is provided in the surface 30 of the pipe 14 extending
the entire thickness (.tau.) of the wall of the pipe 14. A mount
collar 22 is provided that is sized to fit around the opening 44.
The mount collar 22 is generally a ring-shaped or cylindrical element.
The inner diameter of the mount collar is sized to receive a vortex
shedder bar 36 a main pressure bearing element 28 a sensor 12
and optionally a sensor housing 46 and a spacer 40. Generally, the
sensor device 12 is positioned inside the housing 20 and fixed to
the pressure bearing element 28. The sensing device 12 may then
be connected by leads 16 (which are shielded) to processing electronics
18.
[0032] In this embodiment, the mount collar 22 is provided with
fastener openings 48 for receiving a fastener 38 extending through
cover openings 49 provided on the mounting cover 24 and into the
fastener openings 48 provided on the mount collar 22.
[0033] In this embodiment, the shedder bar 26 has a machined cavity
32 or groove sized to receive the pressure bearing element 28. A
seal 50 may be positioned between a wall of the cavity 32 and the
pressure bearing element 28 to provide a tight fit.
[0034] The pressure bearing element 28 includes a pivoting element
31 a cap 42 and a post 29. The post 29 is mechanically connected
to a sensing device 12. Depending on the specific assembly 10 sizing
and configuration, a groove 54 may be provided on a circumferential
edge of the cap 42 for facilitating a weld connection to the sensor
housing 46.
[0035] The sensor 12 may be positioned within a sensor housing
46. Generally, such a sensor housing 46 is sized to fit within the
mounting collar 22. A bottom edge 56 of the sensor housing 46 may
be machined to match to curvature of the inner wall of the pipe
14. Additionally, the outer surface of the sensor housing 46 may
be provided with a ledge or lip 58 for interfacing with a bottom
edge of a spacer. Finally, an inner ring or lip 60 (shown in phantom)
may be provided on the inside surface of the sensor housing 46 to
mate with a bottom surface of the cap 42 of the pressure bearing
element 28.
[0036] A ring seal 62 can be used to provide a fluid seal between
the fluid flow within the pipe 14 and the sensor 12 by positioning
the ring seal 62 on lip 60. In the alternative embodiment, the ring
seal 62 is provided on the inside lip (not shown) of the mounting
collar 22.
[0037] A spacer 40 interfaces with the outside ridge 58 of the
sensor housing 46 to translate pressure from the mounting cover
24 onto the seals between the sensor housing and the fluid flow.
The pressure exerted by the cover 24 against the spacer 40 maintains
the position of the sensor housing 46 and the shedding bar 26. The
spacer 40 is generally sized to fit within the inside diameter of
the mounting collar 22 and around an outside diameter of at least
a portion of the sensor housing 46. Generally, the spacer 40 is
positioned to press against the ridge 58 of the sensor housing 46.
[0038] The various elements shown in FIG. 3 may be provided as
a single pre-fabricated assembly for insertion. For example, the
shedding bar 26 the main pressure element 28 the cap 42 and the
pressure sensor 12 and the pressure sensor housing 46 can be provided
as a single unit. The shedding bar 26 the sensor housing 46 and
the pressure bearing element 28 may be cast as a single piece. The
mounting collar 22 and cover 24 may be sold separately from the
single unit, allowing customers to make their own choice as to how
to attach the unit to the pipe 14. Alternatively, all of the components
may be sold together.
[0039] FIG. 4 shows a simplified flow diagram for installation
of the present invention. First, a hole is drilled in one surface
of the pipe (step 410). Generally, the hole or opening 44 extends
entirely through the thickness (.tau.) of the pipe 14 allowing
access to the fluid flow within the pipe 14. A mounting collar 22
(or flange or bracket) is attached to the pipe 14 around the pipe
opening 44 (step 420). Generally, the mounting collar 22 has a ring-shape
with an inner diameter sized to allow a vortex flow meter assembly
to be inserted into the mounting collar 22 and through the opening
44 in the pipe 14. The vortex assembly is then inserted into the
mounting collar 22 through the opening 44 and into the pipe 14
such that the shedding bar 26 extends the entire diameter (d) of
the pipe 14 to reach the opposing inner surface of the pipe 14 (step
430).
[0040] Finally, spacing element 40 and cover 24 of the mounting
collar 22 are fixed in position with fasteners 38 to hold the components
in position (step 440).
[0041] As shown in FIG. 5A, the mounting collar 22 can be manufactured
to have a relatively low profile, while the cover 24 can be manufactured
to have a relatively higher profile. In this embodiment, the mounting
collar 22 is welded to the pipe 14 (the mounting collar/pipe weld
joint is indicated by reference numeral 64). The cover 24 can then
be attached to the mounting collar as discussed with respect to
earlier figures, or can be welded to the mounting collar (the cover/collar
weld joint is indicated by reference numeral 66). Leads 16 extend
out from the cover 24 and may be attached to additional processing
circuitry 18 (shown in FIG. 1).
[0042] As shown in FIG. 5B, a flange element 68 can be used to
attach the flow meter assembly to the pipe 14. In this embodiment,
the flow meter assembly includes the shedding bar 26 the pressure
bearing element 28 the sensor 12 and leads 16. As shown, the flange
element 68 is circular; however, the flange element 68 may be of
any shape or size to fit around the opening. The shedder bar 26
(shown in phantom) extends the entire diameter of the pipe, and
leads 16 extend from the sensing element (not shown) out through
the cover 24. Depending on the size of the sensor and the thickness
of the wall of the pipe 14 there may be insufficient room for the
processing electronics 18 (shown in FIG. 1) to be positioned within
the attached assembly. Consequently, in certain circumstances, the
leads 16 may extend from the sensing device 12 and may need to be
shielded to guard against stray capacitances. processing electronics
18 may then be attached to the outside of the pipe 14 or may be
connected at a location that is remote from the sensor assembly.
[0043] As shown in FIG. 5C, a gauge or dial 70 is attached to the
outer surface of the cover 24 providing a user friendly display
representative of a measured vortex frequency. In this embodiment,
process circuitry 18 and a sensor element 12 may be positioned within
the housing 20 of the vortex flow meter assembly 10 and the display
can be adapted to indicate a fluid flow rate.
[0044] FIG. 5D shows another alternative embodiment of the present
invention including a wireless transmitter 72 attached to the cover
24 of the flow meter assembly 10. In this embodiment, leads 16 extend
from the sensor 12 (not shown), which senses the motion of the pressure
bearing element 28 (not shown). Process circuitry 18 may be positioned
within the housing 20 or on the cover 24 of the housing 20 to process
the sensed data and to transmit the data wirelessly to a control
center (not shown). The wireless transmitter 72 may also include
an external antenna 74 for facilitating the sending and receiving
of wireless signals 76. Finally, in this embodiment, the mounting
collar 22 is welded to the pipe 14 (the mounting collar/pipe weld
joint is indicated by reference numeral 64).
[0045] Referring now to FIG. 6A, depending on the size of the diameter
(d) of the pipe 14 and particularly for larger pipes having a high
volume flow, it may be necessary to support the shedding bar at
a distal end 36. As shown, the flow meter assembly 10 is inserted
through an opening in the pipe 14. The mounting collar 22 is fixed
to the surface of the pipe via weld 64. The main pressure bearing
component 28 extends into a cavity 32 in the proximal end 34 of
the shedder bar 26. The bearing element 28 is attached to a cap
42 which is held in place by a sensor housing 46 and a spacer 40
which are in turn held down by the cover 24. The cover 24 is attached
to the mounting collar 22 by fasteners 38 which may be threaded
screws, bolts, rivets or any other type of fastener. In this embodiment,
the shedding bar 26 extends a full diameter (d) of the pipe 14 and
into a recessed area 78 in the inner wall of the pipe 14. In general,
any reinforcement element for the distal end 36 of the shedding
bar 26 should be positioned approximately opposite the opening 44
on the inside wall of the pipe. In this embodiment, the reinforcement
element is the recessed area 78 which is preferably positioned
opposite the opening 44 in the pipe 14.
[0046] An expanded view of the recessed portion 78 of the pipe
14 is shown in FIG. 6B. Specifically, a recess 78 is machined in
the inner surface of the wall of the pipe 14 on the side that is
directly opposite to the opening 44. The recessed portion 78 is
sized to receive the distal end 36 of the shedding bar 26.
[0047] FIG. 7 shows an alternative embodiment of a reinforcing
element 80 for supporting the shedding bar 26. As shown, the reinforcing
element 80 is a notch or bump on the inner wall surface of the pipe
14 directly behind (relative to the direction of flow) the distal
end 36 of the shedding bar 26. The reinforcing element 80 supports
the shedding bar 26 against bending moments. Other reinforcing elements
are also contemplated, such as a dimple sized to receive a protrusion
on the distal end of the shedding bar 26 (see also, for example,
reference numeral 46 and associated discussion in U.S. Pat. No.
4717159 which is incorporated herein by reference).
[0048] As shown in FIGS. 8A and 8B, a notch or ridge 82 is machined
on the inner surface of the pipe 14 on the wall opposite the opening
44. The ridge 82 extends into the fluid flow, and is sized to match
a corresponding recess 84 in the shedding bar 26. When the shedding
bar 26 is positioned properly, the recess 84 mates with the ridge
82 to provide support for the distal end 36 of the shedding bar
26.
[0049] In FIGS. 9A-9D, an alternative embodiment of a support or
reinforcing element is shown. In this embodiment, the support element
86 extends into the fluid flow from the surface of the inner wall
of the pipe 14. The support element 86 is curved or "cupped"
to receive the distal end 36 of the shedding bar 26.
[0050] As shown in FIG. 9B, the shedding bar is divided into three
distinct parts including a head section 88 having a flow face 90
an intermediate body section 92 that is integral with and immediately
downstream from the head section 88 and a tail section 94 that
is downstream from and integral with the intermediate body section
92. As shown, the support element 86 surrounds the tail section
94 of the shedding bar 26 along its distal end 34. The fluid flow
direction is indicated by the arrow denoted by reference numeral
96 and the vortices caused by the shedding bar 26 are indicated
by reference number 98.
[0051] FIG. 9C illustrates the shedding bar 26 in position within
the curved area of the support element 86. The support element 86
extends from the surface of the pipe 14 and cups the distal end
36 of the shedding bar 26.
[0052] FIG. 9D illustrates that the shedding bar 26 extends to
the surface of the pipe 14 within the curvature of the support element
86. The portion of the distal end 36 of the shedding bar 26 that
is within the curved support element 86 is shown in phantom behind
the supporting element 86.
[0053] In general, the pressure bearing element or main pressure
bearing component 28 is classified as a category 11 111 or IV
pressure accessory according to the European Pressure Equipment
Directive 97/23/EC. Both sides of the pressure bearing element are
identically machined.
[0054] In general, the insertion vortex meter of the present invention
is designed to work on larger diameter pipes, such as 12 inch pipes
or larger. While the invention can be used with smaller pipes, generally
the cost advantage of doing so may be too small, and the installation
process with a smaller pipe may be less efficient, depending on
the specific implementation. In other words, with smaller diameter
pipes, the insertion vortex flow meter may be neither economical
nor desirable. However, depending on the size, and particularly
with larger sizes such as pipes having six-inch diameter or larger,
the present invention provides significant cost savings in materials
for the parts. Specifically, the large amounts of steel that go
into a standard vortex meter body can be replaced by the smaller
assembly of the insertion vortex flow meter of the present invention.
[0055] In general, the vortex flow meter of the present invention
can be installed as described above, or in any of the ways that
ANNUBARS that are currently installed. Thus, the vortex flow meter
can be installed using a simple flange mounted to the pipe, using
a mounting ring or collar as discussed above, or using a mounting
apparatus or assembly. Suitable mounting assemblies include the
PAK-LOK system shown in U.S. Pat. No. 4717159 which is incorporated
herein by reference, the flow-tap method shown in U.S. Pat. No.
4633713 or other similar pipe mounting systems or techniques.
[0056] In general, the present insertion vortex assembly solves
the problem of high cost of the prior art. By using the insertion
technique, the present invention replaces two large flanges and
a meter body with one smaller assembly.
[0057] All insertion meters have the cost advantage of not having
two flanges and a meter body for attachment between two pipe sections.
This cost advantage explains why insertion-type meters are desirable
for larger pipe size applications, in part because the flanges and
the meter body require more metal for larger pipe sizes, thereby
increasing the unit costs. The advantage of the design of the present
invention over other types of meters is that the averaging effect
of the vortex shedding bar extending across the entire diameter
of the pipe makes the insertion vortex flow meter as accurate as
a vortex meter in a traditional meter body.
[0058] Finally, the vortex flow meter assembly 10 of the present
invention may be scaled fairly simply. By machining the assembly
as separate component elements, components can be replaced or substituted
as needed. More importantly, increasing the size of the insertion
vortex meter simply requires machining of a larger shedding bar
26. The other component elements can be used with other sized bars
with little alteration. Importantly, this allows for the same component
architecture to be manufactured to scale with little or no adjustment
over are wide range of line sizes, approximately 4 inch diameter
pipes to 24 inch or larger pipes. Thus, the vortex flow meter assembly
10 of the present invention provides a scalable, efficient, and
cost effect alternative to standard meter body vortex meters.
[0059] Although the present invention has been described with reference
to preferred embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention. |