U.S. patent application number 13/105599 was filed with the patent office on 2011-12-15 for floating device providing noise reduction properties.
This patent application is currently assigned to ARMACELL ENTERPRISE GMBH. Invention is credited to Heribert QUANTE, Mark SWIFT, Jurgen WEIDINGER.
Application Number | 20110303483 13/105599 |
Document ID | / |
Family ID | 42988354 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110303483 |
Kind Code |
A1 |
QUANTE; Heribert ; et
al. |
December 15, 2011 |
FLOATING DEVICE PROVIDING NOISE REDUCTION PROPERTIES
Abstract
The present invention relates to a floating noise reduction
system for moving and/or falling fluids, the process for
manufacturing of such system and the use of such system.
Inventors: |
QUANTE; Heribert;
(Marienmuenster, DE) ; SWIFT; Mark; (Queensbury,
GB) ; WEIDINGER; Jurgen; (Munster, DE) |
Assignee: |
ARMACELL ENTERPRISE GMBH
Munster
DE
|
Family ID: |
42988354 |
Appl. No.: |
13/105599 |
Filed: |
May 11, 2011 |
Current U.S.
Class: |
181/294 |
Current CPC
Class: |
G10K 11/162 20130101;
F28C 1/10 20130101 |
Class at
Publication: |
181/294 |
International
Class: |
E04B 1/84 20060101
E04B001/84 |
Foreign Application Data
Date |
Code |
Application Number |
May 21, 2010 |
EP |
10 163 520.9-2213 |
Claims
1-9. (canceled)
10. A system for noise reduction of moving fluids, including waves,
comprising at least one open cell absorption layer and at least one
mixed cell absorption and drainage layer wherein both layers, the
open cell and the mixed cell layer are obtained from expanded
polymer based material showing a total average density of less than
1000 kg/m.sup.3.
11. The system according to claim 10 wherein the mixed cell layer
contains at least 70% closed cells and shows a density of less than
700 kg/m.sup.3.
12. The system according to claim 10 wherein the open cell layer
shows a density of less than 500 kg/m.sup.3.
13. The system according to claim 10 wherein the open cell layer
comprises reticulated foam.
14. The system according to claim 13 wherein the reticulated foam
shows a cell structure of 10 to 300 pores per inch, wherein the
polymer based material cell wall columns show a diameter thinner
than the average cell diameter.
15. The system according to claim 10 wherein the mixed cell layer
comprises at least one of polyolefin or polyalkylidene
terephthalate.
16. The system according to claim 10 where at least one of drainage
holes or ridge structures are applied in at least one of the mixed
cell layer or the open cell layer.
17. A process for manufacturing the material according to claim 10
comprising forming said layers in at least one of a moulding and
adhesion process, continuous extrusion process or co-lamination,
followed by applying said system to a desired structure.
18. A system according to claim 10, for noise reduction of moving
fluids, flowing fluids, falling fluids or fluids creating
waves.
19. The system of claim 11 wherein the mixed cell layer density is
less than 300 kg/m.sup.3.
20. The system of claim 12 wherein the open cell layer density is
less than 200 kg/m.sup.3.
21. The system of claim 14 wherein said cell structure is 20 to 120
pores per inch.
22. The system of claim 18, for noise reduction of water channels,
water ponds, in cooling towers or at shores.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from European patent
application No. 10 163 520.9-2213 filed on May 21, 2010, all of
which is incorporated herein by reference in its entirety for all
purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to a floating noise reduction
system for moving and/or falling fluids, the process for
manufacturing of such system and the use of such system.
BACKGROUND OF THE INVENTION
[0003] Falling or dropping and flowing fluid, especially water, is
known to create significant noise that becomes a health and safety
concern for work personnel and a nuisance for nearby residents. A
prominent case is in cooling towers of power plants where costly
measures have to be taken to reduce the noise. The conditions in
cooling towers are among the worst for any sound dampening
installation, as there is a permanent high water impact like from a
waterfall moving round in circles. The resulting force can cause
severe damage or at least accelerated fatigue to installations of
any kind. Additionally, there has to be appropriate, i.e. highly
efficient, drainage as any sound damping installation of course has
to work above the water surface situation at the base of the tower.
Thus, if a system can work under cooling tower conditions it is
likely to work everywhere, e.g. also when applied on flowing
fluids.
[0004] Some scope in sound attenuating systems has been put on
cooling tower noise reduction for a.m. reasons. As the most
widespread method, a noise protection wall around the base of the
cooling tower is 1. costly and 2. only will reduce the noise
emitted at ground level but not the noise escaping through the top
opening, other measures had been examined. One approach consists in
applying grid-like or mesh-like systems that should disperse the
water flow and the noise, subsequently, such as in CN 200972335, CN
100533033, CN 2341088 and CN 2453381. The claimed noise reduction
of 15-30 dB of the latter could not be reproduced during our
examinations. Honeycombs as damping elements are mentioned in CN
2823955 and CN 1862206, but honeycombs or hollow systems in general
are notorious for creating resonance sound, or "drumming", of
course. All the a.m. systems are mainly based on metalwork and/or
rigid plastics and thus do not possess material immanent dampening
properties. To improve that situation, JP 8200986 claims the use of
a combination of water permeable and non-permeable synthetic resin
mats, however, also those materials are rather rigid and the
drainage properties--despite the claimed drainage ridges--are poor,
leading to water agglomeration on top of the mat which will
increase the noise level again. CN 2169107 mentions damping mats
and particles; however, the claimed system is not able to provide
sufficient structural integrity for the application. Another
approach is focussing on plate systems where the plates themselves
are supported by a damping device and also disperse water, such as
in CN 201003910, CN 201302391, CN 201302392, CN 201302393, CN
201184670, CN 1945190 (all describing combinations of rotating and
fixed plates, partially combined with pipe systems), CN 201311202
(microporous plates), CN 2821500 (plates, rings and surface
structures as known from acoustic indoor systems), JP 56049898
(complex metalwork with damping inlays). Other systems described in
the literature are: CN 2447710 and CN 2438075 (use of floating
balls) and CH 451216, DE 3009193, DE 1501391, DE 2508122, EP
1500891, SU 989292. The latter documents, as well as a publication
(M. Krus et al: Latest developments on noise reduction of
industrial induced draft cooling towers, Veenendaal, 2001, pp
33-38) all mainly refer to systems consisting of floating devices
which are supporting or carrying the damping system, consisting of
mat-like structures, means, some elasticity or flexibility has been
acknowledged to be beneficial for sound dampening; JP 58033621 at
last mentions that "soft cover" may reduce falling water noise (for
sluice doors). However, those systems are not consequently using
the potential of elastic dampening and exhibit deficiencies in
floating properties as well as in drainage performance; and some
systems again are sensitive to mechanical impact.
SUMMARY OF THE INVENTION
[0005] A major object of the present invention thus is to provide a
floating noise reduction system or material combination not showing
the above mentioned deficiencies but exhibiting a significant and
sustainable level of noise reduction over all concerned frequencies
and showing an additional drainage effect and high mechanical wear
resistance.
[0006] Surprisingly, it is found that such system or material not
showing the above mentioned disadvantages can be made from a
combination of expanded elastic material with a floating mechanical
support made from expanded polymer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the accompanying drawings,
[0008] FIG. 1 schematically illustrates the composition of claimed
system,
[0009] FIG. 2 schematically illustrates the skeleton (reticulated)
structure,
[0010] FIG. 3 schematically illustrates the damping of flowing or
falling fluid or waves,
[0011] FIG. 4 schematically illustrates the possible surface
structures for drainage and absorption for layers (A) and (B),
[0012] FIG. 5 schematically illustrates the test layout for falling
water noise detection, and
[0013] FIG. 6 shows the frequencies being damped by claimed
materials: 1/3 octave band spectra resulting from falling water
test.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The claimed material comprises at least one layer (A) of
expanded polymer based material with open cell (open porosity)
structure (FIG. 1). The polymer based material of (A) can be
expanded from an elastomer and/or thermoplastic elastomer (TPE)
and/or thermoplastic and/or thermoset based polymer mixture, or
combinations thereof, and can optionally be crosslinked to improve
mechanical (e.g. compression set) and wear properties. Preferred
are polymer based materials providing elasticity to (A), either by
elastic properties provided by the polymer itself (e.g. for
elastomers and TPEs) or by respectively thin, thus flexible
expanded structures, or by a combination of both. The polymer based
material is expanded by physical and/or chemical expansion agents
to an open cell sponge or reticulated (skeleton) structure,
depending on the required damping and drainage properties.
Preferred is a reticulated (skeleton) structure where the polymer
based cell walls are reduced to columns showing a diameter thinner
than the average cell diameter (see FIG. 2). The polymer based
material can be a mixture or compound that may contain fillers,
such as oxides, carbonates, hydroxides, carbon blacks, recycled
(ground) rubber, other recycled polymer materials, fibres etc., and
additives, such as flame retardants, biocides, plasticizers,
stabilizers, colours etc., of any kind in any ratio. The polymer
base mixture may be crosslinked by any applicable mean of
crosslinking, such as sulphur, peroxide, radiation, bisphenolics,
metal oxides, polycondensation etc. (A) can show various densities,
preferred are densities lower than typical fluids, e.g. lower than
700 kg/m3, to prevent sinking even when fully soaked. Especially
preferred are densities lower than 300 kg/m3. It is easily feasible
to use various combinations of polymer based compounds and various
combinations of layers (A) made thereof. (A) will quickly absorb
the falling or flowing fluid, disperse its impulse into smaller
drops and in parallel will disperse the resulting impact energy
transversally into the matrix of (A). This dispersion will continue
through the open cell structure and into layer (B) and finally will
lead to noise absorption within the claimed material and
transmission of remaining noise into the fluid underneath when
damping falling fluid, or into the medium above or outside when
damping flowing fluid, or into a lateral medium when damping e.g.
waves (see FIG. 3). Meanwhile the absorbed fluid itself will be
silently drained through (A) and (B) to the fluid underneath or
into the medium above or drained laterally. Layer (B) thus not only
acts as floating and draining part of the system, but supports the
noise reduction by interaction with (A) and by providing further
potential for damping additional frequencies. (A) can be of flat
surface to the falling fluid, or it can be structured to alter the
absorption/dispersion properties, and it can be equipped with e.g.
pin holes for better drainage. (A) can also be structured on its
face to (B) for same reason, e.g. for drainage or sound decoupling
purposes (see FIG. 4). Preferred materials for the manufacturing of
(A) are elastomers, such as NR, IR, SBR, NBR, CR, IIR, EPM, EPDM,
Q, etc., thermoplastic elastomers, such as TPP, TPV, TPU, SAN, SEBS
etc., PIR/PUR or polyurethanes, especially reticulated
polyurethanes, polyesters, phenolic and melamine based
compounds.
[0015] The claimed system comprises at least one layer (B) of
expanded polymer based material different or same as for (A) with
either open or closed cell structure (FIG. 1). The polymer based
material of (B) can be expanded from an elastomer and/or
thermoplastic elastomer (TPE) and/or thermoplastic and/or thermoset
based polymer mixture, or combinations thereof, and can optionally
be crosslinked to improve mechanical (e.g. impact strength) and
wear properties. Preferred are polymer based materials providing
structural integrity to (B) to prevent breaking or warping of the
system. The polymer based material is expanded by physical and/or
chemical expansion agents to an open cell sponge or closed cell
foam, depending on the required mechanical, damping and drainage
properties. Preferred is a minimum 50% closed cell structure,
especially preferred are at least 70% closed cells to prevent
soaking and saturation with fluid. The polymer based material can
be a mixture or compound that may contain fillers, such as oxides,
carbonates, hydroxides, carbon blacks, recycled (ground) rubber,
other recycled polymer materials, fibres etc., and additives, such
as flame retardants, biocides, plasticizers, stabilizers, colours
etc., of any kind in any ratio. The polymer base mixture may be
crosslinked by any applicable mean of crosslinking, such as
sulphur, peroxide, radiation, bisphenolics, metal oxides,
polycondensation etc. (B) can show various densities, preferred are
densities significantly lower than typical fluids, e.g. lower than
500 kg/m3, especially preferred are densities lower than 200 kg/m3.
It is easily feasible to use various combinations of polymer based
compounds and various combinations of layers (B) made thereof. (B)
comprises a structure to ensure good drainage properties as (B) is
responsible to draw the fluid away from (A) into the fluid
underneath. This structure can comprise pin holes that can be
applied in a wide variety of size and pattern and combinations. The
structure can also comprise ridges of any shape in any combination
(e.g. triangular, sinus-like, rectangular, trapezoidal etc.) that
can be applied on one or both surfaces of (B) (see FIG. 4). (B) can
be fixed to (A) by mechanical means, or chemically by bonding, or
by a combination of both. Layers (A) and (B)--and optionally
(C)--can be brought together directly by co-forming, e.g. by
co-extrusion and/or co-moulding and/or lamination, and/or can be
connected after giving shape to them. The connection can be
achieved by adhesives, e.g. one or two part silicone, polyurethane,
acrylate, chloroprene, contact adhesives or hot melts or any
combination thereof. Or the connection can be achieved by direct
melting or welding the two materials together, such as by UHF
welding or the like. The preferred final form is a mat or tile like
multilayer compound system. The tiles can easily be cut and shaped
to fit any geometry of the fluid basin or fluid track to float on.
Preferred materials for the manufacturing of (B) are elastomers,
such as NR, IR, SBR, NBR, CR, IIR, EPM, EPDM, Q, etc.,
thermoplastic elastomers, such as TPP, TPV, TPU, SAN, SEBS etc.,
PIR/PUR or polyurethanes, polyesters, phenolic and melamine based
compounds. Especially preferred are compounds providing high impact
strength, such as polyalkylidene terephthalates.
[0016] The claimed material furthermore may comprise one or more
additional layers (C) within and/or between layers (A) and/or (B)
that may provide additional drainage and/or damping and/or other
properties, such as preferably reinforcement, impact resistance
etc. The layers (C) can e.g. comprise fibres, e.g. as mesh, or
nonwoven, wire mesh, resin sheet etc. of any kind; see FIG. 1.
[0017] The claimed material furthermore may comprise a link system
(D) that connects individual pieces, e.g. tiles, comprising layers
(A), (B), and optionally (C) together, but still leaving room to
move and float. (D) can comprise metalwork, woven bands, elastic
links etc., or a combination thereof. (D) is fixed either into
layer (B)/(C)--as the structurally toughest ones--or into the
system, i.e. (B), from underneath or above or by a combination of
both methods. Care has to be taken that (D) will not negatively
influence the floating properties (weight) and the flexibility of
the whole system. Cardan joints or axle bearing based links or
other flexible linking methods are therefore preferred. An
accordingly strong layer (C) between (A) and (B) can also take the
part of (D) if the pieces of (A) and (B) are connected onto (C)
keeping some distance between the respective tiles. However, a
connection system (D) is preferred where individual tiles can be
easily exchanged, e.g. for maintenance purposes.
[0018] It is a prominent advantage of the claimed material that it
is providing excellent damping together with draining effect due to
its composition and structure and that it additionally shows
built-in anti-fatigue properties due to its composition, allowing
long-term use even under harsh conditions.
[0019] A further advantage of the claimed material is the
possibility to adapt its properties to the desired property profile
(concerning mechanics, damping/absorption, fluid intake,
hydrophilic or hydrophobic character, porosity etc.) This can be
achieved by modifying the expansion agent(s), the expansion process
and the polymer base material composition, as well as the density,
and, if required, the crosslinking system(s). The material thus can
be altered to damp/absorb from high to low frequencies or frequency
bands (see FIG. 6), and it can be used in contact with a broad
variety of fluids, including aggressive and/or hot or cold
ones.
[0020] Another basic advantage of the claimed material is the fact
that its noise reduction properties are very constant over a wide
temperature range leading to the fact that its performance remains
unchanged no matter if it is used in summer or wintertime.
[0021] It is a further important advantage of the claimed material
that it will reduce both the ground level noise as well as the top
level noise at cooling towers (see table 1 and FIG. 6), rendering
noise protection walls obsolete.
[0022] It is another important advantage of the claimed material
that it can be applied for noise reduction both of falling/dropping
and flowing fluids.
[0023] It is another advantage of the claimed material that it is
environmental friendly as it does not comprise or release harmful
substances, does not affect water or soil or nature in general and
as it is recyclable by separating the layers and then grinding or
melting them individually.
[0024] A resulting advantage of the material is the fact that it
can be blended or filled with or can contain scrapped or recycled
material of the same kind to a very high extent not losing relevant
properties significantly, which is especially the case for (B) and
(C).
[0025] It is another advantage of the claimed material that its
expanded structure provides insulation properties, thus, it can be
beneficial for keeping fluids warm or cold in addition to the
damping properties.
[0026] It is a prominent advantage of the claimed material that it
can be produced in an economic way in automatic or semi-automatic
shaping process, e.g. by moulding, extrusion and other shaping
methods. It shows versatility in possibilities of manufacturing and
application. It can be extruded, co-extruded, laminated, moulded,
co-moulded etc. as single item or multilayer already and thus it
can be applied in almost unrestricted form.
[0027] It is a further advantage of the claimed material that it
can be transformed and given shape by standard methods being
widespread in the industry and that it does not require specialized
equipment.
[0028] It is another advantage of the claimed material for the
application that it is long-lasting and durable, however, easy to
change in case of maintenance and thus will reduce running costs
for the user.
EXAMPLES
[0029] Preparation of Test Samples
[0030] 1. Floating layer (B): an extruded, expanded and cut PET
board of 25 mm thickness and 1000.times.1000 mm width
(ArmaStruct.RTM., Armacell, Munster, Germany) was coated with a
silicone adhesive layer (ELASTOSIL.RTM. R plus 4700, Wacker Chemie,
Munchen, Germany) to give the floating part of the system. A sinus
shape ridge structure (distance peak to peak of 35 mm) was applied
to one surface by thermoforming embossing and pin holes of 20 mm
diameter were drilled into the board in a distance of 80 mm.
[0031] 2. Sponge like open cell absorbing layer (A): A rubber
compound (Armaprene.RTM. N H, Armacell, Munster, Germany) was
extruded, expanded and cut to an open cell foam mat of 25 mm
thickness and 1000.times.1000 mm width and then laminated onto the
plain surface of (B) as single or double layer by heating the
composite up to 120.degree. C. in a hot air oven, using the a.m.
adhesive.
[0032] 3. Skeleton structure open cell absorbing layer (A): A
reticulated polyurethane foam mat of the type 80 poles per inch
(SIF.RTM., United Foam, Grand Rapids, U.S.A.) of 25 mm thickness
and 1000.times.1000 mm width was laminated onto the plain surface
of (B) as single or double layer by heating the composite up to
120.degree. C. in a hot air oven, using the a.m. adhesive.
[0033] Experimental Setup
[0034] The experiments were carried out on test equipment proposed
and developed by the University of Bradford, UK (Prof K.
Horoshenkov). The setup (see FIG. 5) comprised of a large
underfloor concrete water tank. The tank was 2.5 m deep, 1.8 m wide
and 2.35 m long and was able to hold approximately 8 m3 of water.
The water was discharged onto the underfloor tank from a perforated
water tank mounted above. The perforated water tank was made of PVC
and its dimensions were 0.55 m wide.times.0.55 m long.times.0.2 m
deep. In order to simulate the discharge typical to that measured
in a cooling tower the perforated water tank had 243 holes all 1 mm
diameter wide drilled in a 5 mm thick base, the spacing between the
perforations was approximately 26 mm. The size of the perforations
was chosen in accordance with the ISO 140, Part 18 (2006) and
corresponds to that required to generate heavy rain. The perforated
water tank was calibrated to deliver 5 m3/m2/hr discharge. This
required a water supply at the rate of 20.8 litres per min. The
calibration was carried out by using a standard flow meter and by
weighing the amount of water discharged from the hose pipe over 15
sec intervals. It required the PVC water tank to be filled with 180
mm of water to achieve the equilibrium between the water pick-up
and runoff.
[0035] The absorber foam samples (A) were tested in single and
double layer configurations placed on top of the floating layer (B)
by adhesion as described above. The distance between the top
surface of the top foam layer and the bottom of the perforated
water tank was kept 2 m in all the experiments to ensure the same
terminal velocity of the water droplets. The following items of
equipment were used for sound recording and analysis:
[0036] (i) one PC with WinMLS 2004 build 1.07E data acquisition and
spectrum analysis software and 8-channel Marc-8 professional sound
card.
[0037] (ii) four calibrated Bruel and Kjaer microphones, 1/2'' type
4188.
[0038] (iii) one 4-channel B & K Nexus conditioning amplifier
type-2693 set at 1V/Pa.
[0039] The audio channels were calibrated to 94 dB using a standard
B&K microphone calibrator (Type 4230, no: 1670589). The
1/3-octave sound pressure level spectra were measured on the four
channels and used to calculate the mean 1/3-otave level spectrum
and the broadband sound pressure level (see FIG. 6). The lateral
positions of the four microphones in the underfloor water tank are
shown in FIG. 5. The microphones were suspended on cables 0.8 m
below the bottom of the perforated water tank. The level of ambient
noise in the laboratory was very low and signal to noise ratio of
better than 20 dB was ensured throughout the tests.
[0040] Results
[0041] Table 1 shows the good damping properties of already a
standard sponge structure open cell material. The noise reduction
effect even gets much better when very open cell ("skeleton
structure") material is applied. Another incremental improvement
can be found in a combination of both.
TABLE-US-00001 TABLE 1 Falling water test: noise reduction of open
cell materials (A) - SpC = Sponge-like open cell structure; SkC =
Skeleton-like open cell structure - in 25 and 50 mm thickness
applied on a given layer of (B) in comparison with the unarmed
water surface (all innovative examples). Avg. sound pressure Type
of layer (A) level (dB) Noise reduction by dB SpC foam 25 mm 68.4
8.2 SpC foam 50 mm 67.6 9.0 SkC foam 25 mm 54.5 22.1 SkC foam 50 mm
54.5 22.1 SkC + SpC (25 + 25 mm) 52.6 24.0 No damping 76.6 n.a.
[0042] The frequencies being damped or absorbed also give an
indication about the performance of the materials and material
combinations. FIG. 6 shows the 1/3 octave band spectra for the
materials of table 1 and proves that the skeleton like structure
also has advantages in damping a broader range of frequencies (the
sponge like structure tends to boom at low frequencies), however,
it can be found, too, that a combination of both materials is
performing slightly better.
* * * * *