U.S. patent application number 11/335585 was filed with the patent office on 2006-08-17 for electrode in a measurement tube of a magnetic-inductive flowmeter.
This patent application is currently assigned to ABB Patent GmbH. Invention is credited to Dieter Keese, Hans-Werner Schwiderski.
Application Number | 20060179931 11/335585 |
Document ID | / |
Family ID | 36144271 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060179931 |
Kind Code |
A1 |
Schwiderski; Hans-Werner ;
et al. |
August 17, 2006 |
Electrode in a measurement tube of a magnetic-inductive
flowmeter
Abstract
Electrode in an internally lined measurement tube of a
magnetic-inductive flowmeter, having an electrically conductive
mount which can be loaded mechanically, characterized in that the
mount is provided at least on its side facing the measurement tube
interior with a multilayer film, comprising at least one first
electrically conductive thin film composed of an element of the
first or the eighth group in the fourth, fifth or sixth period of
the periodic table of the elements, as well as a second
electrically conductive thin film, which covers the first thin film
and has good resistance to abrasion and corrosion.
Inventors: |
Schwiderski; Hans-Werner;
(Norten-Hardenberg, DE) ; Keese; Dieter;
(Wahlsburg, DE) |
Correspondence
Address: |
BUCHANAN INGERSOLL PC;(INCLUDING BURNS, DOANE, SWECKER & MATHIS)
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
ABB Patent GmbH
Ladenburg
DE
|
Family ID: |
36144271 |
Appl. No.: |
11/335585 |
Filed: |
January 20, 2006 |
Current U.S.
Class: |
73/152.29 ;
73/152.35 |
Current CPC
Class: |
G01F 1/584 20130101 |
Class at
Publication: |
073/152.29 ;
073/152.35 |
International
Class: |
E21B 47/10 20060101
E21B047/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 21, 2005 |
DE |
10 2005 002 904.3 |
Claims
1. Electrode in an internally lined measurement tube of a
magnetic-inductive flowmeter, having an electrically conductive
mount which can be loaded mechanically, wherein the mount is
provided at least on its side facing the measurement tube interior
with a multilayer film, comprising at least one first
electronically conductive thin film composed on an element of the
first or the eighth group in the fourth, fifth or sixth period of
the periodic table of the elements, as well as a second
electrically conductive thin film, which covers the first thin film
and has good resistance to abrasion and corrosion.
2. Electrode according to claim 1 wherein the first thin film is
composed of platinum or gold.
3. Electrode according to, claim 1, wherein the second thin film
composed of an electrically conductive ceramic.
4. Electrode according to claim 1, wherein the second thin film
composed of aluminum titanium nitride (AlTiN) or titanium nitride
(TiN).
5. Electrode according to claim 1, wherein the material of the
first thin film is applied to the mount by vapour deposition,
sputtering, laser ablation, electrochemical deposition, chemical
vapour deposition (CVD) or epitaxially.
6. Electrode according to claim 1, wherein the material of the
second thin film is applied to the first thin film by vapour
deposition, sputtering, electrochemical deposition or by chemical
vapour deposition (CVD).
7. Electrode according to claim 1, comprising a mount composed of
stainless steel.
8. Electrode according to claim 1, which is fitted in a
hermetically sealed form into the internal lining of the
measurement tube.
9. Electrode according to claim 2, wherein the material of the
first thin film is applied to the mount by vapour deposition,
sputtering, laser ablation, electrochemical deposition, chemical
vapour deposition (CVD) or epitaxially.
10. Electrode according to claim 9, wherein the material of the
second thin film is applied to the first thin film by vapour
deposition, sputtering, electrochemical deposition or by chemical
vapour deposition (CVD).
11. Electrode according to claim 10, comprising a mount composed of
stainless steel.
12. Electrode according to claim 11, which is fitted in a
hermetically sealed form into the internal lining of the
measurement tube.
Description
[0001] The invention relates to an electrode in an internally lined
measurement tube of a magnetic-inductive flowmeter, having an
electrically conductive mount which can be loaded mechanically,
according to the precharacterizing clause of Claim 1.
[0002] The basic design and method of operation of
magnetic-inductive meters are described, for example, in the
German-Language Dictionary of Measurement and Automation, published
by Elmar Schrufer, VDI-Verlag, Dusseldorf 1992, pages 262-263. By
virtue of the principle of operation, magnetic-inductive meters can
be used only for measurement of the flow of electrically conductive
fluid substances. Magnetic-inductive flowmeters can be operated
with a conductive signal tap. They then have at least one pair of
signal sensing electrodes, which are installed in the internal
lining of the measurement tube wall and make contact on the inside
of the measurement tube with the fluid flowing through the
tube.
[0003] Metal electrodes are generally used as signal sensing
electrodes in the prior art. DE 4105311C2 describes electrodes of
this generic type which have an electrode mount which can be highly
loaded mechanically and is provided at least on its side facing the
interior of the measurement tube with a film composed of an
electrode material that is highly resistant to corrosion and
abrasion, with the film being formed from a silicate, a carbide, a
borate or a nitride. The film is applied by spraying or soldering,
with the film then being relatively thick and with a large amount
of material being consumed for its production, or it is produced by
borating, nitriding or carbonization of the electrode surface,
which is likewise highly complex.
[0004] For many applications, for example in the foodstuffs
industry, it is also necessary to use a noble and thus expensive
material as the electrode material, for reasons of hygiene,
cleaning capability, chemical resistance and durability.
[0005] The object of the present invention is thus to provide an
electrode in an internally lined measurement tube of a
magnetic-inductive flowmeter, which can be produced easily and at
low cost, while at the same time having a long life.
[0006] The object is achieved by an electrode of this generic type
having the characterizing features of Claim 1.
[0007] Thus, according to the invention, the mount is provided at
least on its side facing the measurement tube interior with a
multilayer film, comprising at least one first electrically
conductive thin film composed of an element of the first or the
eighth group in the fourth, fifth or sixth period of the periodic
table of the elements, as well as a second electrically conductive
thin film, which covers the first film and has good resistance to
abrasion and corrosion.
[0008] In this case, the expression a thin film means an amorphous,
polycrystalline or monocrystalline film of a solid substance, whose
thickness is in the order of magnitude of 1 nanometer to a few
micrometers, based on the definition in the German-Language
Technical Dictionary "Der Brockhaus Naturwissenschaft und Technik,
Band 1 A-Gd, Spektrum Akademischer Verlag GmbH, Heidelberg, 2003",
[Brockhaus--Science and Engineering, Volume 1 A-Gd] under the
keyword "thin films".
[0009] The elements in the first or eighth group in the fourth,
fifth or sixth period of the periodic table of the elements, as
used for the first film according to the invention, include
elements which are suitable for electrodes in magnetic-inductive
flowmeters for widely differing applications, in particular
including critical applications such as the foodstuffs industry.
These are the elements Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Au; Cu, Ag,
Au. In one particularly advantageous embodiment of the invention,
the first film is in this case composed of gold or platinum.
[0010] The advantage of the use of a thin film composed of one of
the stated materials as the first film of the electrode according
to the invention is the saving of expensive materials, and thus low
productions costs. The second thin film, which covers the first
film according to the invention, ensures that the first thin film
is protected against abrasive and corrosive wear during practical
operation of the magnetic-inductive flowmeter, so that a long life
can be achieved in operation despite the film being only very
thin.
[0011] In one highly advantageous embodiment, the second film is
composed of a thin film of an electrically conductive ceramic, for
example composed of AlTiN or TiN. Thin films composed of these
materials are particularly resistant to mechanical abrasion and
chemical corrosion, can be produced easily using known coating
methods, and adhere well to thin first layers composed of the
stated materials.
[0012] The material of the first thin film can be applied to the
mount epitaxially or by vapour deposition, sputtering or laser
ablation, electrochemical deposition or chemical vapour deposition
(CVD).
[0013] The material of the second thin film can be applied to the
first thin film by vapour deposition, sputtering, electrochemical
deposition or by chemical vapour deposition (CVD).
[0014] In one advantageous embodiment, the mount may itself be
composed of stainless steel, which is a widely used cost-effective
material with high mechanical stability.
[0015] In one advantageous embodiment of the invention, the
electrode is fitted in a hermetically sealed form into the internal
lining of the measurement tube. This creates a measurement tube
with an electrode according to the invention in particular for
applications in the foodstuffs industry, or in pharmacy, which can
be cleaned by means of normal chemical and/or biological cleaning
methods, in particular also including so-called "Clean in Place" or
CIP methods without removal of the measurement tube during the
cleaning process.
[0016] The invention as well as further advantageous refinements
and improvements of the invention will be explained and described
in more detail with reference to the drawing, which illustrates one
exemplary embodiment of the invention.
[0017] The single FIGURE shows a schematic cross section of a part
of a measurement tube 1 of a magnetic-inductive flowmeter for
measurement of the flow of electrically conductive fluid
substances, for example water. The tube wall 2 of the measurement
tube 1 is composed of metal, as is normal for magnetic-inductive
flowmeters. It is lined with a tube internal lining 6 towards the
internal area 4 through which the fluid flows. The lining 6 on the
inside of the tube is composed of an electrically insulating,
chemically highly resistant plastic material, for example Teflon.
The relationships between the dimensions of the measurement tube
wall 2, the lining 6 on the inside of the tube and the electrode 8
in the FIGURE are not to scale, but are illustrated only
schematically.
[0018] The part of the measurement tube illustrated in the FIGURE
has an opening 10 in the measurement tube, in which an electrode 8
is held. The electrode 8 comprises a mount 9 composed of stainless
steel, with a T-shaped form. The longitudinal mount bar 12 is
guided in an electrically insulated manner in the opening 10,
although the isolation layer is not shown here. The transverse
mount bar 14 is held in a corresponding recess in the lining 6 on
the inside of the tube, in such a way that that surface 16 of the
electrode 8 which points towards the inside of the measurement tube
ends flush and hermetically sealed with the inner face of the
lining 6 on the inside of the tube.
[0019] The transverse mount bar 14 for the electrode 8 is provided
with a two-layer film composed of two thin films. First of all, a
thin film 18 composed of platinum is applied to the transverse
mount bar 14 as the first film, over which a second thin film 20
composed of TiN is then applied. Both films are electrically
conductive.
[0020] By way of example, the vapour deposition process is used for
production of the first thin film 18 composed of platinum. The
first film 18 is a thin film with a film thickness between a few
nanometers and a few micrometers. The production of thin platinum
films such as these on stainless steel mounts is known from the
prior art. It is also used for large-scale production, using
so-called batch methods, by way of example for the production of
platinum films on silicon chips for semiconductor purposes. As an
alternative to vapour deposition, the platinum film can also be
deposited by sputtering, by laser ablation, or by chemical vapour
deposition (so-called CVD process), epitaxially or by
electrochemical deposition.
[0021] The second film 20 composed of TiN is likewise a thin film
and is produced by sputtering, although it could also be produced
by later ablation or by chemical vapour deposition (so-called CVD
processes). The application of TiN films is also known from the
prior art, for example for semiconductor purposes, where it is also
used for large-scale production. The coating method can thus be
carried out highly cost-effectively. The TiN film 20 is used as a
protective layer against corrosion and abrasion for the first
measurement electrode film 18.
[0022] The two-layer system shown in the FIGURE, comprising the
platinum film 18 and the TiN film 20, allows the electrode 8 to be
used even in critical applications, in particular in the foodstuffs
industry or in the pharmaceutical industry where the inner surfaces
of the magnetic-inductive meters which touch the substance being
measured are subjected to particularly stringent requirements,
especially with regard to hygiene and cleaning capability. The
fitting and installation of the electrode 8 according to the
invention and its installation in the tube wall 2 of the
magnetic-inductive meter, as illustrated in the FIGURE, allow the
magnetic-inductive meter to be cleaned without removing it from the
process pipeline, using a so-called CIP (Cleaning in Place)
process. In this case, as is known, a generally highly alkaline,
hot cleaning solution is passed through the process pipeline
system, including all of the fittings and meters installed there
which carry the measurement substance, instead of the measurement
fluid at particularly regularly recurring intervals, thus removing
organic and inorganic contamination. The inner surfaces of the
process pipeline system which touch the measurement substance can
then also be subjected to hot-steam sterilization. All of these
cleaning and disinfection steps result in very stringent
requirements for the corrosion and abrasion resistance of the
measurement electrodes, and these requirements can be satisfied by
a two-layer structure according to the invention.
[0023] The embodiment shown in the FIGURE is, of course, not the
only possible embodiment for electrodes according to the invention.
All other types of electrode mounts and their installation in
magnetic-inductive meters are also covered by the invention,
provided only that these electrodes are provided with a multilayer
structure according to the invention on their side facing the
measurement tube interior.
[0024] The present application claims priority under 35 USC
.sctn.119 to German application number 10 2005 002 904 3, the
disclosure of which is hereby incorporated by reference in its
entirety.
* * * * *