U.S. patent application number 16/584111 was filed with the patent office on 2020-02-06 for apparatus for cleaning industrial components.
The applicant listed for this patent is TECH SONIC LIMITED PARTNERSHIP. Invention is credited to Byron KIESER, William Lash PHILLIPS, Shawn SMITH.
Application Number | 20200038919 16/584111 |
Document ID | / |
Family ID | 44196169 |
Filed Date | 2020-02-06 |
United States Patent
Application |
20200038919 |
Kind Code |
A1 |
PHILLIPS; William Lash ; et
al. |
February 6, 2020 |
APPARATUS FOR CLEANING INDUSTRIAL COMPONENTS
Abstract
An apparatus for cleaning industrial components has a liquid
container defining a liquid enclosure for containing a cleaning
liquid and ultrasonic transducers having an operating frequency and
a wavelength in the cleaning liquid and secured to at least a
portion of the liquid container at a spacing of between 2 and 10
wavelengths. In operation, the transducers generate a larger power
density in the component-receiving area of the liquid container
than an average power density of the liquid container.
Inventors: |
PHILLIPS; William Lash;
(Medicine Hat, CA) ; SMITH; Shawn; (Fort McMurray,
CA) ; KIESER; Byron; (Beeton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TECH SONIC LIMITED PARTNERSHIP |
St. Albert |
|
CA |
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|
Family ID: |
44196169 |
Appl. No.: |
16/584111 |
Filed: |
September 26, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13518248 |
Aug 23, 2012 |
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PCT/CA2010/002016 |
Dec 22, 2010 |
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16584111 |
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61289050 |
Dec 22, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B08B 3/12 20130101 |
International
Class: |
B08B 3/12 20060101
B08B003/12 |
Claims
1-49. (canceled)
50. A method of cleaning industrial components, the method
comprising the steps of: fixedly securing resonating rod ultrasonic
transducers to an inner surface of at least a portion of a liquid
container in a two dimensional plane at a spacing of between 2 and
10 wavelengths between adjacent ultrasonic transducers in a radial
direction relative to an axis of the ultrasonic transducers and
based on an operating frequency and operating wavelength of the
ultrasonic transducers in a cleaning liquid; introducing the
cleaning liquid into the liquid container such that a minimum
liquid level is reached and the ultrasonic transducers are
submerged in the cleaning liquid; introducing an industrial
component into the cleaning liquid and positioning the industrial
component in a component-receiving area of the liquid container
that is spaced from the ultrasonic transducers; and operating the
ultrasonic transducers to generate a uniform energy density in the
component-receiving area of the liquid container that is greater
than an average power density in the liquid container.
51. The method of claim 50, wherein operating the ultrasonic
transducers comprises operating the ultrasonic transducers at a
frequency between 20 kHz and 30 kHz.
52. The method of claim 50, wherein at least some of the ultrasonic
transducers are out of phase.
53. The method of claim 51, wherein the ultrasonic transducers
generate frequencies about a center frequency of 25 kHz.
54. The method of claim 50, wherein the ultrasonic transducers
comprise one or two active ultrasonic heads.
55. The method of claim 50, wherein the liquid container is a
liquid tank having an open top.
56. The method of claim 50, wherein the liquid container is a
liquid tank with a removable or retractable top cover.
57. The method of cairn 50, wherein the industrial component is a
set of heat exchanger tubes.
58. The method of claim 57, wherein the set of heat exchanger tubes
are between 2 feet and 150 feet in length and between 6 inches and
12 feet in diameter.
59. The method of claim 50, wherein the liquid container comprises
a sloped bottom surface.
60. The method of claim 59, wherein the sloped bottom surface is
one of flat, concave or "V" shaped.
61. The method of claim 50, wherein the ultrasonic transducers
generate a power density within the liquid container, when filled
with the cleaning liquid, of between 10-60 Watts/gallon.
62. The method of claim 50, wherein the ultrasonic transducers are
mounted vertically to the inner surface of the liquid
container.
63. The method of claim 62, wherein the ultrasonic transducers are
mounted using a compliant clamping at a top of the ultrasonic
transducer, and a mount device that does not restrict motion along
the axis of the ultrasonic transducer.
64. The method of claim 50, wherein the liquid container comprises
an aqueous based degreasing surfactant solution having a pH between
7-11.
65. The method of claim 50, wherein the liquid container comprises
an aqueous cleaning solution comprising at least one of solvent
additives, an acid solution, and an alkaline solution.
66. The method of claim 50, wherein the component-receiving area is
positioned about 5-10 wavelengths away from the ultrasonic
transducers.
67. The method of claim 50, wherein the ultrasonic transducers are
operated to create an acoustic approximation of a planar transducer
at 5-10 wavelengths from the ultrasonic transducers.
Description
FIELD
[0001] This relates to a method and apparatus for cleaning
industrial components, particularly heat exchangers.
BACKGROUND
[0002] Heat exchangers and other industrial components, such as
pipe spools, valves, fittings, pipe sections, etc. become fouled
during operation and require periodic cleaning. The types of
components that become fouled will vary depending on the industry.
Cleaning is important because the operational efficiency of these
components depends on the surfaces being clean and free of
contamination to allow proper heat exchange, flow, velocity,
mixing, control to occur during an industrial process.
[0003] Traditional methods for cleaning industrial components of
the type described herein have involved the use of high pressure
water to mechanically dislodge and wash contaminants, chemical
rinse or soak to dissolve contaminants, mechanical (abrasive)
cleaning or a combination of all three.
[0004] Heat exchangers are used to effect the exchange of heat
energy between two media. In some cases this exchange may be for
the purposes of cooling a process fluid, and in other cases it may
be to increase the temperature of a fluid. In most cases the media
are separated by a material through which the heat must pass,
typically a metal tube of some sort. A very common type of heat
exchanger is the "shell and tube" design, in which one media flows
through a complex arrangement, or "bundle" of tubes inside a larger
shell through which a second media flows, by a tortuous path,
through the tube bundle. Examples of typical shell and tube heat
exchangers are shown in FIGS. 1a and 1b, which serve to demonstrate
the complexity of such a device. Heat exchangers, represented by
reference numeral 102 in FIG. 1a and 103 in FIG. 1b, contain
exchanger tubes 106 that generally have a straight tube exchanger
bundle (shown partly extracted from the shell) or a bent "U tube"
design. In FIG. 1a, there is a bent or "U" tube 102 design and in
FIG. 1b, there is the more common straight tube 103 design. The
shell 104 serves as the conduit for one of the media via a tortuous
path, directed by baffles 105 through the tube bundle 102 or 103 in
which the media contacts the outer diameter 107 of the exchanger
tubes 106. The tube sheet 103 serves to hold the tubes 106 in a
specific arrangement as a bundle, and to separate the two media
(between the shell and the tubes) and allow the 2.sup.nd media to
pass through the inner diameter of the heat exchanger tubes. In
service, both the inner and outer diameters of the tubes comprising
the bundle may become fouled with contaminants such that the flow
rate through the tubes, and/or the heat transfer properties of the
tubes are negatively affected, resulting in a loss of efficiency in
the overall process. There are many other types of heat exchanger
designs, including plate exchangers, in which two or more fluid
media are separated by thin metal plates, arranged in closely
spaced stacks such that alternate spaces are filled with alternate
media. The plate exchanger design provides a large surface area for
contact between the media but is particularly difficult to clean
owing to the compactness of the exchanger, the fact that it cannot
typically be disassembled, and the small fraction of the plate
surface accessible for traditional mechanical cleaning methods.
[0005] Similarly, tube sections, pipe spools, valves and other
components both upstream and downstream of the heat exchanger may
become fouled to the extent that the efficiency of the overall
process is reduced, and these components typically require cleaning
on a schedule similar to that of the heat exchangers that they are
in line with. Other industrial components in systems that don't
include heat exchangers may also become fouled and require
cleaning.
[0006] The composition of the fouling is determined by the media
and the conditions (temperature, pressure, velocity, surface
properties, etc.) present in the process media. For example, in the
oil and gas industry, heavy crude oil presents bitumen and
asphaltene foulants, which can severely restrict and in some cases
entirely block tubes, valves and heat exchangers. In the chemical
industry, polymer or partially polymerized contaminants are common
and in the food industry, heavy fats, caramelized sugars and
microbial contaminants are often seen. Hard scaling, derived from
cooling water is also seen across all industries where water is
used as a cooling media.
[0007] Cleaning fouled industrial components has most commonly been
done using high pressure water jetting (blasting). This technique
involves using high pressure pumps, both hand-held and automated,
at between 15,000-50,000 psi, to deliver a variety of water streams
to the contaminated part to dislodge the contaminant material. This
technique has limited success on complicated surfaces not only
because of the lack of solubility of many of the contaminants and
the concreted nature of the contamination, but also the complexity
of the tube bundle, exchanger plates, valve part or tube section,
which makes direct impact to much of the surface to be cleaned by
the water jet impossible. The water blasting technique is also
quite dangerous, requiring the operator to wear armour, and
resulting in thousands of workplace injuries in North America each
year, including fatalities. Furthermore, the high pressure water
jetting methods are very time consuming. A single heat exchanger
may require up to a week of continuous, 24 hours per day blasting,
with a 3 man crew of operators to remove the bulk of the
fouling.
[0008] Chemical cleaning of industrial components such as heat
exchangers, tubes and valves may also be done using a chemical
rinse strategy in which the process fluid is substituted for a
chemical designed to dissolve contaminants. This methodology
requires often large volumes of hazardous chemicals and often fails
to remove the contamination completely due to the complicated
liquid flow patterns within the system or due to plugged
tubes--through which no chemical rinse can flow.
[0009] Purely mechanical cleaning methods using abrasives (such as
sand blasting) are typically used in only the most extreme cases,
partly because these techniques suffer from some of the same risks
and deficiencies as high pressure water jetting, but also because
of the potential surface impacts (damage) to the materials of the
parts being cleaned.
[0010] Another option for cleaning components is with the use of
ultrasonic energy, such as described in Canadian Patent No.
2,412,432 (Knox) entitled "Ultrasonic Cleaning Tank" which
describes a tank in which industrial components are cleaned with
the aid of ultrasonic energy.
SUMMARY
[0011] There is provided an apparatus comprised of a vessel, to
which ultrasonic transducers are secured in such a way as to direct
ultrasonic energy, which, when combined with a suitable cleaning
fluid, may be used to clean industrial components, such as heat
exchangers, contained within the vessel. The ratio of ultrasonic
transducers to liquid volume provides a nominal energy density in
the vessel of between 5 and 25 watts per gallon, however the
arrangement (spacing) and operation (power and type) of the
transducers provides non-uniform energy densities in and about the
objects to be cleaned of greater than 20 watts per gallon in
certain locations. The spacing of the transducers at between 2 and
10 wavelengths distance within the container is designed to provide
a uniform energy field, which maintains higher than nominal energy
density within the vessel in the volume in which the component to
be cleaned is housed.
[0012] There is provided an apparatus comprised of a vessel, to
which ultrasonic transducers are secured in such a way as to direct
ultrasonic energy, at frequencies between 20 kHz and 30 kHz, which,
when combined with a suitable cleaning fluid, may be used to clean
industrial components, especially heat exchangers, contained within
the vessel. The frequency of the transducers may be operated
between 20-30 kHz which provides wavelengths of ultrasonic energy
suitable for cleaning industrial scale components, such as heat
exchangers.
[0013] The transducers used in one example of the apparatus deliver
2000 watts of energy each, at a nominal centre frequency of 25 kHz,
by use of a "push pull" design, such as those described in U.S.
Pat. No. 5,200,666 (Walter et al.) entitled "Ultrasonic
Transducer", in which a metal rod is caused to resonate by the
application of ultrasonic energy at both ends of the rod, through
the expansion and contraction of piezoelectric crystal elements
stacked inside a transducer or converter device attached to each
end of the rod. The vibrations created by the longitudinal
expansion and contraction of the piezoelectric elements, sometimes
referred to as thickness mode, are primarily expressed by the
resonant rod as radial vibrations (relative to the axis of the rod)
by ensuring that the rod length is correctly tuned to the resonant
frequency of the transducer elements, which operate synchronously
and are attached to each end of the rod.
[0014] Because of the radial radiation of ultrasonic energy from
the rod transducers used in the example described above, spacing of
the transducers is important to ensure a uniform energy field in
the container. Normally, the energy transmitted from the transducer
radially decreases (attenuates) in proportion to the square of the
distance from the transducer. To prevent this, transducers are
spaced at integral wavelength distances of between 2 and 10
wavelengths, typically between 4 and 24 inches in the preferred
frequency range. This arrangement creates an acoustic approximation
of a planar transducer at distances from the transducers of
approximately 5-10 wavelengths, and provides a much more uniform
energy density in the volume in which an object is to be cleaned.
The power density in the container may be calculated as the total
output of all transducers in the liquid container in Watts divided
by the volume of the container in U.S. Gallons. Preferably, when
the container 500 is full of cleaning fluid to the minimum liquid
level, provides between 10-60 Watts/gallon. The power density may
also be calculated for specific volumes of the container, such as
around the component to be cleaned.
[0015] According to another aspect, the transducers may be powered
by suitable electronic generators which deliver electrical energy
in a form suitable to cause the transducers to resonate between 20
kHz and 30 kHz, with a typical centre frequency of 25 kHz, a to
dissipate between 500 and 3000 Watts per individual resonating rod
transducer, or up to 60000 Watts for immersible plate style
transducers.
[0016] According to another aspect, the transducers may operate at
a nominal frequency (e.g. 25 kHz) which is controlled by the
electronic generators, and the frequency of the transducers are
allowed to fluctuate about the nominal frequency in order to
maintain maximum power output, and may be fluctuated intentionally
to prevent cavitation damage to equipment by standing waves. In
some circumstances, it may be preferred to avoid any control of the
phase of sound waves between adjacent transducers, such that
transducers are allowed to operate at slightly different and
variable frequencies. In at least some circumstances, the effect of
the varying frequencies creates a dynamic energy field, which
enhances cleaning action and at the same time reduces the potential
for damage to components by static standing waves of high
energy.
[0017] According to another aspect, there is provided an
appropriate cleaning fluid based on a proper assessment of the
contaminants fouling the components to be cleaned is necessary. For
asphaltenes, bitumen and other heavy crude oil derivatives, it has
been found that an aqueous based degreasing solution, with near
neutral pH, such as Paratene D-728 produced by Woodrising Resources
Ltd. of Calgary, Alberta provides excellent performance, and
relatively simple disposal. In some cases small amounts of solvent
may be added to the aqueous solution to enhance the removal of
certain contaminants. In some other cases, it is necessary to use
strongly acidic or basic cleaning fluids to address specific
contaminants, such as polymers, epoxies, scales, etc. The choice of
materials in construction of the container is therefore important
and it has been discovered that while normal (or "carbon") steels
perform well as structural elements, and as container walls in
strictly near neutral applications, stainless steel is preferred as
a wall material to avoid corrosion in the case of non-neutral
cleaning fluids. Other construction materials may also be used
based on the anticipated cleaning fluid and contaminants as will be
recognized by those skilled in the art.
[0018] According to another aspect, the liquid container may be
formed by the shell or modified shell of an existing heat
exchanger.
[0019] There is therefore provided, according to an aspect, an
apparatus for cleaning industrial components, comprising a liquid
container defining a liquid enclosure for containing a cleaning
liquid; and ultrasonic transducers having an operating frequency
and a wavelength in the cleaning liquid and secured to at least a
portion of the liquid container at a spacing of between 2 and 10
wavelengths. In operation, the ultrasonic transducers generate a
larger power density in the component-receiving area of the liquid
container than an average power density of the liquid
container.
[0020] According another aspect, there is provided a method of
cleaning industrial components, comprising the steps of: securing
ultrasonic transducers to at least a portion of a liquid container
at a spacing of between 2 and 10 wavelengths based on the operating
frequency and wavelength of the ultrasonic transducers in a
cleaning liquid; introducing the cleaning liquid into the liquid
container such that a minimum liquid level is reached and all
ultrasonic transducers are submerged in the cleaning liquid;
introducing an industrial component into the cleaning liquid; and
operating the ultrasonic transducers to generate a larger power
density in the component-receiving area of the liquid container
than an average power density of the liquid container.
[0021] According to another aspect, the transducers may generate a
frequency between 20 kHz and 30 kHz, and may generate frequencies
about the centre frequency of 25 kHz. At least some of the
transducers simultaneously may generate different frequencies
between 20 kHz and 30 kHz. At least some of the transducers may be
out of phase
[0022] According to another aspect, the transducers may be secured
to an inner surface of the liquid container, or an outer surface of
the liquid container. The transducers may be plate-type
transducers, or resonating rod transducers. The resonating rod
transducers may comprise one or two active ultrasonic heads. The
transducers may generate a power density within the liquid
container when filled with liquid of between 10-60 Watts/gallon.
The transducers may be mounted vertically, horizontally and/or
diagonally to the inner surface of the liquid container. The
transducers may be mounted using a compliant clamping at a top of
the transducer, and a mount device that does not restrict motion
along the axis of the resonant rod.
[0023] According to an aspect, the container may be a liquid tank
having an open top. The container may have a removable or
retractable top cover. The container may be sufficiently large to
receive a set of heat exchanger tubes that may be between 2 feet
and 150 feet in length and between 6 inches and 12 feet in
diameter. The bottom of the liquid container may be flat, concave,
or "V" shaped.
[0024] According to an aspect, the liquid container may be an outer
shell containing a set of exchanger tubes.
[0025] According to an aspect, the liquid container may comprise an
aqueous based degreasing surfactant solution having a pH between
7-11, an aqueous cleaning solution comprising at least one of
solvent additives, an acid solution and an alkaline solution, an
aqueous cleaning solution comprising an acid solution, or an
aqueous cleaning solution comprising an alkaline solution.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] These and other features will become more apparent from the
following description in which reference is made to the appended
drawings, the drawings are for the purpose of illustration only and
are not intended to be in any way limiting, wherein:
[0027] FIG. 1a is an exploded perspective view of a typical tube
and shell heat exchanger, showing the tube bundle and shell,
[0028] FIG. 1b is a side view in section of the tube and shell heat
exchanger shown in FIG. 1a.
[0029] FIG. 2 is a perspective view of an apparatus for cleaning
industrial components.
[0030] FIG. 3a is a perspective view of an apparatus for cleaning
industrial components that is designed to clean 5'.times.30' heat
exchanger.
[0031] FIG. 3b is an end elevation view in section of the apparatus
shown in FIG. 3a.
[0032] FIG. 3c is a top plan view of the apparatus shown in FIG.
3a.
[0033] FIG. 3d is a side elevation view of the apparatus shown in
FIG. 3a.
[0034] FIG. 4a is a perspective view of an alternative apparatus
for cleaning industrial components having a vertically-oriented
tank.
[0035] FIG. 4b is a top plan view in section of the alternative
apparatus shown in FIG. 4a.
[0036] FIG. 4c is a side elevation view in section of the
alternative apparatus shown in FIG. 4a.
[0037] FIG. 5a is a side elevation view in section of an apparatus
for cleaning exchanger tubes constructed from the shell of the heat
exchanger.
[0038] FIG. 5b is an end elevation view of the apparatus shown in
FIG. 5a.
[0039] FIG. 6a is a perspective view of an alternative apparatus
for cleaning industrial components that is designed to clean
smaller heat exchangers and valves.
[0040] FIG. 6b is a top plan view of the alternative apparatus
shown in FIG. 6a.
[0041] FIG. 6c is a side elevation view of the alternative
apparatus shown in FIG. 6a.
[0042] FIG. 7 depicts an example of a resonating rod style
transducer.
[0043] FIG. 8 depicts an example of a plate-type transducer.
[0044] FIG. 9 is a side elevation view in section of a transducer
mount that may be used to mount the transducers in the
apparatus.
[0045] FIG. 10 is a perspective view of an alternative apparatus
that is designed to clean industrial components up to a size of
6'.times.31'.
DETAILED DESCRIPTION
[0046] Ultrasonic cleaning employs the use of ultrasonic sound
waves to disrupt the normal liquid diffusion layer about a surface
to drastically increase the rate of reaction (interaction) between
a surface contaminant and the cleaning fluid. In addition,
cavitation created in the liquid, near the surface, by the
compression and rarefaction induced by the incident sound waves,
creates high pressure and high temperature microjets, which aid in
physically disturbing contaminants at the surface and dislodging
them into the cleaning liquid.
[0047] By combining ultrasonics with a suitable cleaning liquid,
for example a near neutral pH, water based surfactant
solution/degreaser, components may be cleaned effectively in a
fraction of the time required by traditional methods described
above.
[0048] The present discussion relates to an improvement on
ultrasonic cleaning tanks, which increases the effectiveness and
broadens the situations in which they can be used, including use on
larger or more complex industrial components.
[0049] In particular, the ultrasonic transducers used in
association with the cleaning tank are placed relatively close
together, such as between 2 to 10 wavelengths apart, or between 2
to 6 wavelengths apart, or between 6 and 10 wavelengths apart. This
causes the ultrasonic waves generated by transducers to interfere
with each other. It has been found that, by doing so, the gradient
of the power density resulting from the ultrasonic waves in the
cleaning tank may be modified, such that the penetration of the
ultrasonic waves through the tank is increased. Once the principles
described herein are understood, a person of ordinary skill will
understand the relationship between the ultrasonic waves generated
by the transducers and the power density induced in the cleaning
liquid by these waves. The transducers are operated such that the
frequency and phase of adjacent transducers are not controlled
simultaneously, which prevents the formation of static and possibly
damaging standing waves in the cleaning liquid.
[0050] Referring to FIG. 2, there is shown a container 200 having
side walls 202 and 203, end walls 204 and 205, a sloped and curved
bottom plate 201, and an end baffle 206 to support immersed parts
and prevent them from sliding into the end wall 205. The container
200 is constructed using appropriate structural design practices
for vessels which will contain liquids, and typically will include
structural elements such as vertical and horizontal stiffening
beams, support plates, etc., which are not detailed here but will
be understood by those skilled in the art and familiar with this
type of container design. The inside of side walls 202 and 203 of
the container 200 are fitted with ultrasonic transducers 207,
mounted using top mounts 208 and bottom mounts 209 such that the
transducers are approximately 4 wavelengths apart (e.g. 10''
centers). The mounting height of the transducers preferably follows
the slope of the bottom plate 201 so as to maintain proximity to
long objects placed in the container 200 that rest on the bottom
plate 201. Guard bars 210 are positioned between transducers 207 to
prevent accidental damage to the transducers 207 from contact by
large components in the tank. The container 200 is preferably
fitted with lifting lugs 211 to facilitate movement of the
container 200, and to facilitate slings used to support objects
suspended in the container 200 for cleaning. Drain ports 213 may be
included to facilitate removal of cleaning fluid. A skid assembly
212 may be integrated into the design to facilitate movement of the
container 200 on the ground and from tilting transport
vehicles.
[0051] FIG. 3a -3d show an example apparatus, generally indicated
by reference numeral 300 in FIG. 3a, that is built for cleaning
heat exchangers and other components up to 5 feet in diameter and
30 feet in length. In addition to the features outlined in other
examples, this example is constructed with catwalks 304 supported
by struts 305, fitted with handrails 308 and accesses by stairways
306 & 307. These components may be included to improve the
safety of workers, and for ease of use. In addition to the
sidewalls 309 & 310, the end walls 311 & 312 and the sloped
bottom 313, the container may also be fitted with supports 314 that
permit the fixing of a hard or flexible cover over the container.
The cover is used to help maintain the temperature in the liquid
container, if it is heated. It may also be used to prevent
evaporative losses. Electrical cables from the transducers 315 are
preferably gathered in cable runs 316, 317 and 318 where they will
exit the container and be connected to the electrical amplifiers
(generators) providing the signal to the ultrasonic
transducers.
[0052] FIG. 4a-4c show an alternate vertical example of the
apparatus, which was constructed to accommodate immersion of heat
exchangers and pipe sections such that debris from the parts would
readily fall to the bottom of the container and could be easily
pumped out or drained, and other types of components that would
benefit from a vertically oriented tank. This container is
constructed of four side walls 403, 404, 405, 406 and a bottom
plate 407 and a removable top cover 408. Transducers 409 are shown
as being mounted at a 45 degree angle, approximately 10 wavelengths
apart (approximately 24'') and separated by guards 410, which
prevent any accidental damage to the transducers by contact from
components being cleaned while in the tank and during immersion or
removal. A drain port 411 is provided for convenient removal of the
cleaning fluid or lower layer of debris and contamination. Lifting
lugs 412, 413 & 414 are provided to facilitate removal and
support of the tank during operation.
[0053] FIGS. 5a and 5b show an alternate example of the apparatus,
in which the container is formed by the shell of the heat exchanger
itself, and transducers are mounted within the shell. In this
example, the shell 501 forms the cleaning container being comprised
of side walls in the form of a pressure vessel tube. Transducers
502 are mounted inside the shell by any convenient method, in this
case through the use of baffles 503, which hold the transducers 502
in place, to provide the ultrasonic energy for cleaning of the
exchanger bundle (not depicted) in-situ, that is, without the need
for removing the bundle from the shell 501. The baffles 503 are
designed to work with the baffles of the tube bundle to promote a
tortuous path of liquid flow during operation from the inlet 505 to
the outlet 506. An intrinsically safe interface at a plate added to
the shell manifold 504 is preferably provided for the wiring used
to transmit the electrical energy to the transducers 502.
Transducers 502 used in this configuration are of a commercially
available intrinsically safe type, being filled with an inert,
non-conductive fluid. As depicted, the transducers 502 are
horizontally-mounted rod-type transducers. However, plate-type
transducers externally bonded to the shell, or immersible
transducers otherwise supported within the shell may also be used,
as will be understood by those skilled in the art.
[0054] FIG. 6a-6c shows a smaller example of the apparatus, built
for the cleaning of smaller components, such as heat exchangers,
valves, etc. The apparatus, generally indicated by reference
numeral 600 in FIG. 6a, is comprised of a container formed of side
walls 603 & 604, end walls 605 & 606 and bottom plate 607
with transducers 608 mounted vertically on the side walls and
horizontally on the end walls 605 and 606. Because the volume of
the container is significantly smaller than some of the larger
examples, transducer spacing is not as important, and in this
example, the transducers are mounted with approximately a 7
wavelength spacing, or approximately 17''. The apparatus is
preferably equipped with folding guard plates 609 which serve to
protect the transducers and provide a conduit for the wiring needed
to supply the transducers with the electrical energy required. The
apparatus is further preferably equipped with a catwalk 610 held in
place by struts 611, a drain plug 612 and skid tubes 613 far easy
handling with a forklift. Lift lugs 614 are preferably provided to
the container to be lifted as well as to sling components within
the container during cleaning.
[0055] An electronic ultrasonic generator system is used to supply
ultrasonic power (for example, in the form of alternating current
at 25 kHz) to the transducers. A suitable electronic generator is
available from Crest Ultrasonics Corp. located in Trenton, N.J. The
type of generator selected will depend on the preferences of the
user and the requirements of the particular design. The transducers
are connected to the generators via electrical wiring, which
connects each transducer to an appropriate supply of electrical
energy. In some examples, each transducer may require a generator
to power it. In other examples, commercially available
transducer/generator equipment may be used that allows more than
one transducer to be supplied by a single generator. In some
circumstances, only certain transducers may be active, such that
there will be only certain areas of the tank that are actively
cleaning components. In other circumstances, specialized tanks may
only mount transducers in certain areas, such as to clean specific
portions of components.
[0056] FIG. 7 shows an example of a resonating rod ultrasonic
transducer 700. The transducer 700 is has a resonating rod 701
attached by a coupling device 702 & 703 to so called
"transducer heads" 704 & 705 which are comprised (internally)
of a stack of piezoelectric crystals 706 connected electrically in
series and backed with a counter weight/heat sink mass 707 which,
under the influence of an alternating electrical voltage, will
expand and contract, creating vibrations that are transmitted to
the resonant rod 701 via the couplers 702 & 703. Each stack of
piezoelectric crystal elements generally has specific resonant
frequencies, some of which result in the radial expansion and
contraction of the crystal, and some of which result in the axial
(or thickness) expansion and contraction of the material. These
typical rod transducers are generally operated at frequencies which
are tuned to the resonant frequency of the system of crystal stacks
and resonant rod. In the preferred examples described herein, the
frequencies used are between 20 and 30 kHz, with 25 kHz being the
normal operating frequency. Rod transducers may be mounted in a
liquid tank in a vertical, horizontal, or diagonal orientation. As
they are mounted in the tank, the spacing of these transducers is
considered for the direction of propagation of ultrasonic waves.
For example, with the rod transducers 701 shown in FIG. 7,
relatively little energy propagates outward from the transducer
heads 704 and 705. Thus, the spacing is measured in the radial
direction, i.e. between parallel rods, rather than the axial
direction, i.e. rods placed end to end. Other types of ultrasonic
transducers are also commercially available and may be used in the
examples described herein in suitable circumstances. For example,
others types of transducers include single head resonant rod
transducers, immersible plate style transducers (as shown in FIG.
8, represented by reference numeral 810), etc. Plate transducers
are commercially available that may be bonded to the outside walls
of the container, or may be fully enclosed and designed to be
immersed. Accordingly, there are a variety of transducers that may
be used to supply ultrasonic energy to the examples described
herein. The design of the container and mounting of the transducers
should be optimized for each style of transducer chosen to provide
a uniform field of ultrasonic energy within the container.
[0057] FIG. 9 shows an example of a transducer mount 900 that may
be used in the apparatuses described herein. The mount 900 has a
top mount 901 and a bottom mount 902 which secure the transducer
912 in place. The design incorporates a clamp for the top head of
the transducer which clamps the head 903 gently between two gaskets
904 & 905, and the mount tube 906 supports the weight of the
transducer in a vertical position. The bottom mount preferably does
not secure the bottom head 907 of the transducer, rather it allows
free vertical motion of the transducer for optimum vibrational
output during operation, while at the same time restricting motion
of the lower transducer head 907 in the horizontal plane by means
of a compliant restraint gasket 908 sandwiched between a guide
plate 909 and the mount plate 910, thus preventing damage from
vibration or torque during shipment of the container. The top mount
901 is bolted to the container wall 911 for easy service removal
and the bottom mount 902 is fixed to the container by weld or
suitable fasteners.
[0058] FIG. 10 shows an apparatus 1000 for cleaning industrial
components which has been built to accommodate 6 foot wide by 31
foot long heat exchangers. This vessel is designed to incorporate
the transducer mount shown in FIG. 9, using 86 dual head resonant
rod transducers of the type described in FIG. 7.
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