BACKGROUND
The invention relates generally to a sensor assembly for measurement of a
parameter of a fluid, and more specifically, to an ultrasonic sensor assembly for sensing
and measuring one or more parameters of the fluid.
It is often required to determine at least one parameter attributed to fluids in a
static state such as stored in containers, tanks, etc., or along flow paths, for example in
pipes. The parameters may include density of the fluid, fluid velocity (kinetic or
4 h dynamic), fluid level, temperature, fluid phase, calorific value or the like. There are a
number of known sensors, which are used for detection of parameters associated with the
fluids.
One such sensor used for detection of parameters associated with the fluids,
commonly known as ultrasonic sensor, includes a sensor rod and a transducer assembly
for generating an ultrasonic wave. One end of the sensor rod is near the transducer
assembly for receiving the ultrasonic wave. Other end of the sensor rod, referred to as
sensing portion, may be immersed either fully or partly in a fluid. As, parameters of fluid
surrounding the sensor rod influence the ultrasonic wave characteristics, the parameters
of fluid are suitably detected. Typically, ultrasonic sensors may be used for sensing at
least one of the parameters of a fluid such as: absolute density, density profile, fluid level,
W absolute temperature, temperature profile, absolute viscosity, viscosity profile, absolute
flow velocity, flow velocity profile, absolute fluid phase fraction, fluid phase fraction
profile, calorific value, or combinations thereof, but not limited thereto. The sensor rod
will have an X, Diamond, Aerofoil or an exemplary shaped sensor portion and may or
may not have a reference portion, which may be of circular cross section. The transducer
generating the ultrasonic wave may be located at one end of the sensor portion. If the
sensor rod includes a reference portion, the transducer is located on the reference portion.
2
Ultrasonic sensors are currently installed in highly controlled environments
such as laboratories and are seldom used in real life conditions because of reasons well
known to users. As a result, there is a continued need for an ultrasonic sensor assembly
that addresses at least one of the above mentioned and/or any other shortcomings.
BRIEF DESCRIPTION
In accordance with one embodiment of the invention, a sensor assembly is
disclosed. The sensor assembly comprises a sensor rod and a holder for securely holding
at least a part of the sensor rod, such that at least a part of the sensor rod is immersed in
the fluid. Further, the assembly comprises an enclosure connected to the holder and a
w transducer assembly mounted in the enclosure. The transducer assembly is located in
proximity of the sensor rod and is arranged to excite an ultrasonic wave along the sensor
rod and receive a reflected wave there from for sensing at least one parameter of the
fluid.
In accordance with another embodiment of the invention, a method of packaging
a sensor assembly is disclosed. The packaging method comprises providing a holder
securely holding at last a part of a sensor rod, such that at least a part of the sensor rod is
immersed in a fluid. The method further comprises mechanically coupling an enclosure
to the holder. The method further comprises mounting a transducer assembly in the
enclosure, wherein the transducer assembly is connected to the sensor rod for exciting an
^ ^ ultrasonic wave along the sensor rod for sensing at least one parameter of the fluid.
DRAWINGS
These and other features, aspects, and advantages of the present invention will
become better understood when the following detailed description is read with reference
to the accompanying drawings in which like characters represent like parts throughout the
drawings, wherein:
3
FIG. 1 is a block diagram of a sensing system including a sensor assembly for
sensing at least one parameter of a fluid flowing through a conduit in accordance with an
exemplary embodiment of the present invention;
FIG. 2 is a cross-sectional view of the sensor assembly in FIG. 1 including an
exemplary enclosure, in accordance with a particular embodiment of the invention;
FIG. 3 is an elaborate cross-sectional view of the sensor assembly in FIG. 1
including packaging in low flow velocity environment, in accordance with a particular
embodiment of the invention;
•
FIG. 4 is a side sectional view of the enclosure taken along section 4-4' as
illustrated in FIG. 3;
FIG. 5 is an elaborate cross-sectional view of the sensor assembly in FIG. 1
including packaging in a high flow velocity environment, according to another
embodiment of the invention;
FIG. 6 is a side sectional view of the enclosure taken along section 5-5' as
illustrated in FIG. 5; and
^ ^ FOG. 7 is a flow chart of a method of packaging a sensor assembly in accordance
^ with an exemplary embodiment of the invention.
It may be noted that, to the extent possible, like reference numerals have been
used to represent like elements in the drawings. Further, skilled artisans will appreciate
that elements in the drawings are illustrated for simplicity and may not have been
necessarily been drawn to scale. For example, the dimensions of some of the elements in
the drawings may be exaggerated relative to other elements to help to improve
4
understanding of aspects of the present invention. Furthermore, the one or more elements
may have been represented in the drawings by conventional symbols, and the drawings
may show only those specific details that are pertinent to understanding the embodiments
of the present invention so as not to obscure the drawings with details that will be readily
apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION
While the invention is susceptible to various modifications and alternative forms,
specific embodiment thereof has been shown by way of example in the drawings and will
be described in detail below. It should be understood, however that it is not intended to
W limit the invention to the particular forms disclosed, but on the contrary, the invention is
to cover all modifications, equivalents, and alternative falling within the spirit and the
scope of the invention as defined by the appended claims.
The parts of the device have been represented where appropriate by conventional
symbols in the drawings, showing only those specific details that are pertinent to
understanding the embodiments of the present invention so as not to obscure the
disclosure with details that will be readily apparent to those of ordinary skill in the art
having benefit of the description herein.
The terms "comprises", "comprising", or any other variations thereof, are intended
^ ^ to cover a non-exclusive inclusion, such that one or more devices or sub-systems or
elements or structures proceeded by "comprises... a" does not, without more constraints,
preclude the existence of other devices or other sub-systems or other elements or other
structures or additional devices or additional sub-systems or additional elements or
additional structures. Similarly, a method step proceeded by "comprising" or any
variation thereof, does not, without more constraints preclude the existence of additional
steps or repetitive steps.
5
Accordingly, the present invention provides a sensor assembly being mountable
for immersion in a fluid and operable to propagate an ultrasonic wave, including a sensor
rod immersible at least partly in the fluid. The sensor assembly further includes an
enclosure connected to the sensor rod. The enclosure includes a transducer assembly
arranged to excite the ultrasonic wave along the sensor rod. The transducer may further
detect a reflected wave along the sensor rod for sensing at least one parameter of the
fluid. The transducer assembly may further include a transducer housing for holding the
transducer. The enclosure may further include a pressure stop plug. The sensor assembly
further includes a holder for securely holding the sensor rod. The holder may be
connected to the enclosure either directly or via an adapter and a lock nut mechanism.
The sensor assembly further includes a means such as a flange, a threaded portion, a flow
w cell or a flange connection mounted in-between the pipe line for attachment for mounting
the sensor assembly in relation to a fluid container or a fluid carrying conduit such that
the sensor rod is at least partly immersed in the fluid. The sensor rod generally includes a
sensing portion and optionally a reference portion. In case the sensor rod comprises the
sensing and the reference portions, a ratio of length of the sensing portion to the reference
portion is chosen based on a ratio of the guided wave group velocities in the fluid
medium. A protective enclosure may be provided around at least a part of the sensing
portion of the sensor rod. The sensor assembly may further include one or more seals
such that the seals restrict leakage of the fluid.
Referring to FIG. 1, a block diagram of a sensing system 10 for sensing at least
^ ^ one parameter of a fluid 12 flowing through a conduit 14 is illustrated. In the illustrated
embodiment and subsequent embodiments, the conduit may be a vertical arrangement or
a horizontal arrangement. It should be noted that even though a conduit is disclosed, the
sensing system 10 is applicable to any device containing a fluid for sensing at least one
parameter attributed to the fluid in both static (for example, a tank) and flowing
conditions. The system 10 includes a sensor assembly 16. The sensor assembly 16 in turn
includes a sensor rod 18 and an enclosure 20 having a transducer 22. The transducer 22 is
in close proximity of the sensor rod 18. The sensor rod 18 is at least partially immersed in
6
I
the fluid 12 flowing through the conduit 14 and includes a reference portion 24 and a
sensing portion 26.
The system 10 further includes an excitation device 28 that generates an
ultrasonic wave for propagation through the sensor rod 18. The excitation device 28 is
coupled to the sensor rod 18 via the transducer 22 for enabling propagation of the
ultrasonic wave through the sensor rod 18. When the sensor portion 26 of the sensor rod
is at least partially immersed in the fluid 12, the ultrasonic wave propagating through the
sensor rod 18 is affected by at least one parameter of the fluid 12 and hence, at least one
parameter of the fluid 12 may be measured by detecting the propagation of wave energy
along the sensor rod 18. The said at least one parameter includes absolute density, density
' w profile, fluid level, absolute temperature, temperature profile, absolute viscosity, viscosity
profile, absolute flow velocity, flow velocity profile, absolute fluid phase fraction, fluid
phase fraction profile, calorific value or combinations thereof of the fluid 12. The fluid 12
may include a single-phase fluid, or a two-phase fluid mixture, or a multi-phase fluid
mixture. It should be noted herein that a two-phase fluid mixture, or a multi-phase fluid
mixture might include two or more fluids having different densities. For example, a
multi-phase fluid mixture may include oil, water, and gas. The excitation device 28 may
further have an ultrasonic wave generator 30 such as but not limited to, piezoelectric,
curved piezoelectric, phased array magneto-strictive, Laser-based electromagnetic
acoustic transducer (EMAT), phased EMAT, CMUT, and an amplifier 32.
^ In the illustrated embodiment, the transducer 22 detects the wave energy from the
sensing portion 26 of the sensor rod 18. A corresponding output signal from the
transducer 22 may be fed via a digital oscilloscope 34 to a processor device 36, for
example, a computer. The processor device 36 may determine at least one parameter of
the fluid 12 in response to the output signal from the transducer 22. It should be noted [
herein that the configuration of the sensing system 10 is an exemplary embodiment and
should not construed in any way as limiting the scope of the invention. The exemplary
sensor rod 18 is applicable to any application requiring detection of at least one parameter
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attributed to the fluid 12 in which the fluid is contained in a vessel or flowing through a
conduit. Typical examples include petroleum industry, oil & gas, pharma industry, or the
like. The exemplary sensor design and arrangement of sensors are explained in greater
detail with reference to subsequent embodiments.
In an embodiment, the sensor rod 18 may have an X shaped, Diamond shaped,
Aerofoil shaped or any other exemplary shaped sensor portion 26 and may or may not
have the reference portion 24. The transducer 22 generating the ultrasonic wave may be
located at one end of the sensing portion 26. In case the sensor rod 18 has the reference
portion 24, the same may be in the form of circular cross section and the transducer 22
may be located on the reference portion 24.
Referring to FIG. 2, a cross-sectional view of an exemplary sensor assembly 100
is illustrated according to an embodiment of the invention. The sensor assembly 100
includes a sensor rod 102 and an enclosure 104 for holding and orienting the sensor rod
102 in the assembly. A holder 106 connected to the enclosure 104 for holding at least one
portion of the sensor rod 102. The enclosure 104 includes a transducer assembly 108
arranged to transmit the ultrasonic wave along the sensor rod 102 for sensing at least one
parameter of the fluid.
Referring to FIG. 3, an elaborate cross-sectional view of the sensor assembly 100
in FIG. 2 in accordance with one embodiment of the present invention for
^ ^ implementation in hazardous and danger prone areas, for example in petroleum industry,
oil and gas, pharma industry where flammable vapor are present around. This
construction may be installed in an area having low fluid velocity is shown. The sensor
assembly 100 may be seen to include a sensor rod 102, an enclosure 104 for holding and
orienting the sensor rod 102 and a holder 106 connected to the enclosure 104 for holding
at least one portion of the sensor rod 102. The enclosure 104 in turn includes a transducer
assembly 108.
8
The sensor rod 102 includes a reference portion 110 and a sensing portion 112.
The reference portion 110 and the sensing portion 112 may have suitable lengths. The
sensor rod may be of any conventional type. By way of example, the sensor rod 102
includes without restriction the torsional sensor rod described in U.S. Patent Publication
No. 2011/0167906 having a publication date of July 14, 2011, assigned to the same
assignee.
The holder 106 runs longitudinally around the axis of the sensor rod 102 and is
positioned below and connected to the enclosure 104. According to a particular
embodiment, the holder 106 is directly connected to the enclosure 106 or may be
connected to the enclosure 104 by means of an adaptor and lock nut mechanism 114 or
W any other suitable mechanism, such as, a bushing mechanism. The holder 106 holds at
least a part of the reference portion 110 of the sensor rod 102. One or more seals 116 are
provided to ensure that the fluid (whose characteristics are being sensed) does not leak. In
one aspect, seals 116 are provided between the holder 106 and the sensor rod 102. In
another aspect, seals 116 are provided between the enclosure 104 and the holder 106.
Additional seals, as may be required, may be additionally placed. The seal 116 may be
made of any of suitable the materials, such as: an elastomer based material, a glass to
metal seal, Ceramic to Metal seal, a graphite etc., sealing material selected such a way
that it can prevent leakage of signal also doesn't dampen the propagation through the
sensor rod but not limited thereto. According to an exemplary embodiment, the seal 116
is incorporated at a location of joining of the holder 106 and the sensor rod 102.
^ ^ According to another exemplary embodiment, the seal 116 is provided at a joining
location of the sensor assembly 100 and the fluid holding means (including a fluid
carrying conduit).
In another embodiment, a means for attachment 118 installs the sensor assembly
100 in an at least partially immersed manner in a hazardous area such as: oil, gas or water
pipeline. The means for attachment 118 in this case may be a flange, a threaded portion, a
flow cell or a flange connection mounted in-between the pipe line on the holder 106 or
9
any other conventional mechanisms. The means for attachment 118 may also be provided
with appropriate seals. According to another embodiment, a pressure stop plug 120 is
provided in the enclosure 104 to absorb fluid pressure generated during high-pressure
conditions.
Referring to FIG. 4, a side sectional view of the enclosure 104 of FIG. 3 taken
along section 4-4' is illustrated. According to an embodiment of the invention, the
transducer assembly 108 includes a transducer 122 and a transducer housing 124. The
transducer housing 124 is supported within in the enclosure 104 using a support means
126. The transducer housing 124 holds the transducer 122 in such a way that the same is
in close proximity of the sensor rod 102. The support means 126 may be a clamp-nut
J P mechanism or a lock-nut mechanism in accordance with one embodiment. Other
alternative mechanisms for securely holding the transducer assembly within the enclosure
known to a person skilled in the art may however be used in place of the aforesaid
mechanisms.
The enclosure 104 includes a coupling arrangement 128 for holding a free end of
the reference portion 110 of the sensor rod 102. The coupling arrangement 128 allows for
alignment and orientation of the sensor rod 102 in a desired direction, such as to
avoid/eliminate ultrasound signal reflections, that may occur when the sensing portion
112 of the sensor rod 102 comes in contact with any hard particles such as: metallic
components in the assembly. It may also be observed that the pressure stop plug 120 is
mounted on top of the enclosure 104.
FIG. 5 illustrates an elaborate cross-sectional view of a sensor assembly 200 in
accordance with another embodiment of the present invention for implementation in
hazardous and danger prone areas where flammable vapor are present around,
particularly in an. area having high fluid viscosity and pressure is shown. The sensor
assembly 200 includes similar components as described above, with reference to FIG. 3.
Apart from the components discussed above, the assembly 200 has a protective enclosure
10
130 assembled around the sensing portion 112 of the sensor rod 102, for implementation
in areas where the fluid flow velocity is high. The presence of the protective enclosure
130 extends the operating pressure range in which the sensor assembly may be used.
According to an exemplary embodiment, the protective enclosure 130 may be made of
materials such as but not restricted to stainless steel or Inconel based alloys, but limited to
it. The protective enclosure 130 protects the sensor rod 102 from any hard particles
hitting the sensor rod and thus, avoids damage to the sensor rod. According to another
embodiment, the protective enclosure 130 is assembled around a part of the reference
portion 110 along with the entire ultrasonic senor portion 112 of the sensor rod 102. The
protective enclosure may also minimize drag force effect on the sensor rod, since any
change in length of the sensor rod affects the signal characteristics due to drag force. The
^ r protective enclosure helps to sustain sensor signal stability even at very high flow rate.
The protective enclosures may be provided with one or more openings for ensuring that
the fluid passes there through and the measurement of the properties of the fluid is
substantially instantaneous also the openings are made in such that the drag force
generated by fluid flow is minimal on the sensor rod. The opening may be in the form of
aperture, hole, notch, cavity, slot, niche, or combinations thereof. The protective
enclosure also regulates the velocity of the fluid, to make the sensing by the sensor rod
insensitive to variations in velocity of the fluid. Thus, in one way the protective
enclosure acts as a sampling system.
Referring to FIG. 6, a side sectional view of the enclosure 104 of FIG. 5 taken
^ along section 6-6' is illustrated. The enclosure illustrated in this drawing is substantially
identical to the enclosure, as illustrated and discussed in FIG. 4. FIG. 6 stands
distinguished from FIG. 4 in terms of the pressure stop plug 120, which is illustrated in
FIG. 6 to be additionally connected to the sensor rod 102. The connection between the
stop plug and the sensor rod is by means of an attachment means 132 and a connecting
pin 134 that fits into a lower end of the stop plug 120. According to yet another
embodiment, the attaching means 132 may also orient the sensor rod 102 in a particular
direction, and thus dampen the vibration induced by flow on the sensor rod 102 and
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protection cover 130 and may also help in avoiding ultrasonic signal reflections and
suppressions that may occur while the assembly is installed in high flow velocity
conditions.
Referring to FIG. 7, a method 300 for packaging a sensor assembly in accordance
with one embodiment of the invention is illustrated. The method includes a step of
providing 302 a holder that securely holds at least a part of a sensor rod such that at least
a part of the sensor rod is immersed in a fluid. The method further includes a step of
mechanically coupling 304 an enclosure to the holder. The method further includes a step
of mounting 306 a transducer assembly in the enclosure. The step of mounting 306 may
further include connecting 308 the transducer assembly to the sensor rod and configuring
^ r 310 the transducer assembly to transmit an ultrasonic wave along the sensor rod for
sensing at least one parameter of the fluid. The step of mechanically coupling 304 may
further include providing 312 a lock-nut mechanism or any other suitable mechanism.
The method may further include providing 314 one or more seals that restrict a leakage of
the fluid. The seals may be provided by way of example, between the holder and the
sensor rod or between enclosure and the holder or at both locations or at any other
suitable or required location. The method may further include providing 316 a protective
enclosure around at least a part of a sensing portion of the sensor rod. The method may
further include providing 318 an attachment means for mounting the sensor assembly in
relation to a fluid container or a fluid-carrying conduit.
^ ^ The present invention provides a sensor assembly which is appropriately
packaged as a single unit and which may be held and aligned with respect to the container
having the fluid whose characteristics are to be determined. The sensor assembly allows
for insertion of a sensor rod straight in the container, such that the sensor rod does not
touch the metallic components in the surroundings and the ultrasonic reflections or
suppressions are avoided. Furthermore, the sensor rod may also include a bend so as to
enable the same to be used in the form of an inflow sensor. Further, the sensor assembly
enables for accurate measurement of the parameters of the fluid under adverse conditions
12
such as extremely high or low- pressure, velocity or temperature. Moreover, the assembly
ensures no fluid leaking occurs while the fluid is under pressurized or non- pressurized
conditions.
The sensor assembly enables the sensor rod to be held in a desired direction and
enables for re-orientation of the rod from outside. The disclosed sensor assembly may be
connected to an enclosure or a container to be used in hazardous conditions such as:
petroleum industry, oil & gas, pharma industry or like pipelines or containers filled with
fluid where the velocity, pressure or temperature keeps varying.
The disclosed sensor assembly may be used in industries and especially in
^ r locations where properties of hazardous fluid are to be measured. The disclosed sensor
assembly provides enhanced Signal to Noise ration (SNR), which is about 2X from the
existing products. This sensor assembly may be used as an ultrasonic sensor for
measuring density of single and multiphase fluids and for mass flow applications. The
disclosed assembly has a simple design, and uses a low cost sensor with no moving parts
for real-time fluids multi property measurement. The sensor assembly provides a highly
accurate measurement of density and multi-property measurement of hazardous fluids.
The sensor assembly may be installed into a pipeline for the instantaneous or in a real
time density measurement of static or in a flowing fluid.
While only certain features of the invention have been illustrated and described
^ ^ herein, many modifications and changes will occur to those skilled in the art. It is
^ ^ therefore, to be understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the invention.

WE CLAIM :
1. A sensor assembly comprising:
a sensor rod;
a holder for securely holding at least a part of the sensor rod, such that at
least a part of the sensor rod is immersed in a fluid;
an enclosure connectable to the holder; and
a transducer assembly mounted in the enclosure, the transducer assembly
being connected to the sensor rod and arranged to excite an ultrasonic wave along
the sensor rod for sensing at least one parameter of the fluid.
^ ^ 2. The sensor assembly of claim 1, further comprising one or more seals such that
the seals restrict leakage of the fluid also prevent the leakage of ultrasonic signal and
doesn't dampen the propagation through the sensor rod.
3. The sensor assembly of claim 1, wherein the enclosure fiirther comprising a
pressure stop plug.
4. The sensor assembly of claim 1, further comprising a means for attachment for
mounting the sensor assembly in relation to a fluid container or a fluid carrying conduit
such that the sensor rod is at least partly immersed in the fluid.
5. The sensor assembly of claim 4, wherein the means for attachment is selected
from at least one of the following: a flange, a threaded portion, flow cell and flange
^ 1 connection mounted in-between the pipe line.
6. The sensor assembly of claim 1, wherein the sensor rod comprises a reference
portion and a sensing portion.
7. The sensor assembly of claim 1, wherein the transducer assembly further
comprises:
a transducer for transmitting an ultrasonic wave and for receiving a
reflected wave along the sensor rod; and
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a transducer housing for holding the transducer.
8. The sensor assembly of claim 1, further comprising an adapter and a lock nut
mechanism or a bushing mechanism for coimecting the enclosure to the holder.
9. The sensor assembly of claim 1, further comprising a coupling arrangement on an
inner side of the enclosure, to securely hold one end of the sensor rod.
10. The sensor assembly of claim 6, further comprising a protective enclosure around
at least a part of the sensing portion of the sensor rod.
11. The sensor assembly of claim 10, wherein the protective enclosure is provided
^ ^ with at least one opening for ensuring that the fluid passes there through and comes in
contact with the sensing portion of the sensor rod.
12. The sensor assembly of claim 10, wherein the opening is the form of aperture,
hole, notch, cavity, slot, niche, or combinations thereof
13. The sensor assembly of claim 6, wherein the sensing portion of the sensor rod is
configured for sensing at least one parameter comprising absolute density, density
profile, fluid level, absolute temperature, temperature profile, absolute viscosity, viscosity
profile, absolute flow velocity, flow velocity profile, absolute fluid phase fi-action, fluid
phase fraction profile, calorific value or combinations thereof, of the fluid.
14. The sensor assembly of claim 13, wherein the sensing portion of the sensor rod is
^ P configured for sensing at least one parameter of a single- phase fluid, or a two- phase
fluid mixture, or a multi- phase fluid mixture.
15. A method of packaging a sensor assembly, the method comprising:
providing a holder securely holding at last a part of a sensor rod, such that
at least a part of the sensor rod is immersed in a fluid,
mechanically coupling an enclosure to the holder; and
15
mounting a transducer assembly in the enclosure, wherein the transducer
assembly is connected to the sensor rod and configured to transmit an ultrasonic
wave along the sensor rod for sensing at least one parameter of the fluid.
16. The method of claim 15, further comprising providing one or more seals
configured to restrict leakage of fluid and prevent leaking of signal, but does not dampen
the propagation through the sensor rod.
17. The method of claim 15, further comprising providing an attachment means
configured to mount the sensor assembly in relation to a fluid container or a fluid
^ carrying conduit.
18. The method of claim 15, wherein mechanically coupling the enclosure to the
holder comprises providing a lock-nut mechanism or a bushing mechanism.
19. The method of claim 15, further comprising providing a protective enclosure
around at least a part of a sensing portion of the sensor rod.
20. The method of claim 19, further comprising providing at least one opening in the
protective enclosure for enabling the fluid to pass there through and come in contact with
the sensing portion of the sensor rod.