U.S. patent application number 14/394406 was filed with the patent office on 2015-03-12 for cathodic protection system.
The applicant listed for this patent is ANODE ENGINEERING PTY LTD. Invention is credited to Wayne Alan Robert Burns.
Application Number | 20150068919 14/394406 |
Document ID | / |
Family ID | 49326953 |
Filed Date | 2015-03-12 |
United States Patent
Application |
20150068919 |
Kind Code |
A1 |
Burns; Wayne Alan Robert |
March 12, 2015 |
CATHODIC PROTECTION SYSTEM
Abstract
An impressed current cathodic protection system for a target
structure susceptible to corrosion (such as of steel or cast iron)
which comprises an inert mixed metal oxide anode surrounded by a
tightly packed conductive zone connected to a power supply source
and having an input/output regulator to control the flow of current
to the target structure. The present invention relates to device
and method to provide personal and/or medical details of one or
more individuals in the event of an emergency.
Inventors: |
Burns; Wayne Alan Robert;
(Paradise Point, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ANODE ENGINEERING PTY LTD |
Upper Mount Gravatt, Queensland |
|
AU |
|
|
Family ID: |
49326953 |
Appl. No.: |
14/394406 |
Filed: |
April 11, 2013 |
PCT Filed: |
April 11, 2013 |
PCT NO: |
PCT/AU2013/000376 |
371 Date: |
October 14, 2014 |
Current U.S.
Class: |
205/724 ;
204/196.06; 204/196.21; 204/196.27; 204/196.36 |
Current CPC
Class: |
C23F 2213/22 20130101;
C23F 2213/32 20130101; C23F 13/16 20130101; C23F 13/14 20130101;
C23F 13/06 20130101; C23F 13/12 20130101; C23F 13/22 20130101 |
Class at
Publication: |
205/724 ;
204/196.36; 204/196.21; 204/196.27; 204/196.06 |
International
Class: |
C23F 13/14 20060101
C23F013/14; C23F 13/22 20060101 C23F013/22 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 11, 2012 |
AU |
2012901419 |
Claims
1. An impressed current cathodic protection system for a target
structure (susceptible to corrosion) comprising: An inert mixed
metal oxide anode surrounded by a tightly packed conductive zone;
Connected to a power supply source; and Having an input/output
regulator to control the flow of current to the target
structure.
2. An impressed current cathodic protection system for a target
structure according to claim 1 in which the target structure is of
steel;
3. An impressed current cathodic protection system for a target
structure according to claim 1 in which the target structure is of
cast iron.
4. An impressed current cathodic protection system according to
claim 1 wherein the anode is comprised of a mixed metal oxide
("MMO").
5. An impressed current cathodic protection system according to
claim 1, wherein at least one of the surface metals in the MMO
anode is selected from the earth derivatives.
6. An impressed current cathodic protection system according to
claim 5 wherein at least one of the surface metals in the MMO anode
is RuO.sub.2.
7. An impressed current cathodic protection system according to
claim 5 wherein at least one of the surface metals in the MMO anode
is IrO.sub.2.
8. An impressed current cathodic protection system according to
claim 5 wherein at least one of the surface metals in the MMO anode
is PtO.sub.0.12.
9. An impressed current cathodic protection system according to
claim 5 wherein the amount of the said metal is up to 10-12 g per
square metre.
10. An impressed current cathodic protection system claim 4,
wherein the other surface metal in the MMO anode is typically in
the form of TiO.sub.2
11. An impressed current cathodic protection system according to
claim 4, in which the interior of the MMO anode is made of a metal
which prevents corrosion of the interior
12. An impressed current cathodic protection system according to
claim 4 in which the interior of the MMO anode is made of
titanium.
13. An impressed current cathodic protection system according to
claim 1 in which the tightly packed conductive zone effectively
increases the active zone of the anode.
14. An impressed current cathodic protection system according to
claim 1 in which the tightly packed conductive zone is in the form
of a powder with a low moisture content.
15. An impressed current cathodic protection system according to
claim 1 in which the tightly packed conductive zone is comprised of
calcined petroleum coke.
16. An impressed current cathodic protection system according to
claim 15 in which the calcined petroleum coke is comprised of:
Fixed carbon: 99.35% Ash: 0.6% Moisture: 0.05% Volatiles: Nil at
950.degree. C. Bulk Density: 74 lbs. per cubic foot. Predominantly
round particles. All particles surface modified for maximum
electrical conductivity. Particle Sizing: Dust free with a maximum
particle size of 1 mm. Minimum calcination temperature of base
materials in excess of 1200.degree. C. Base materials calcined
under specified quality control. Surfactants added to assist
pumping and settling. No de-dusting oils used during the
manufacture of base particles.
17. An impressed current cathodic protection system according to
claim 1 in which the anode and surrounding tightly packed
conductive zone is contained within a tubular sleeve sealed at both
ends.
18. An impressed current cathodic protection system according to
claim 17 in which the tubular sleeve is comprised of a non
degradable permeable synthetic or linen cloth or other suitable
material.
19. An impressed current cathodic protection system according to
claim 1 in which a number of anodes are placed into an anode
bed
20. An impressed current cathodic protection system according to
claim 1 wherein the system is driven by a DC power supply stored in
a sealed battery cell.
21. An impressed current cathodic protection system according to
claim 1 in which the system power supply is provided by means of
solar input power generation and battery storage.
22. An impressed current cathodic protection system according to
claim 21 in which the solar input power generation is in the form
of solar powered cells or panels.
23. An impressed current cathodic protection system according to
claim 1 in which the system power supply is generated by means of
wind power.
24. An impressed current cathodic protection system according to
claim 1 in which the system power supply is generated by means of
thermo electric generators.
25. An impressed current cathodic protection system according to
claim 1 in which the system power supply is generated by means of
turbines.
26. An impressed current cathodic protection system according to
claim 1 in which the total CO.sub.2 footprint for the 1.5 mm
diameter MMO/TiO.sub.2 anode will be about 0.473 kgs/m.
27. An impressed current cathodic protection system according to
claim 1 wherein the power to the structure is controlled by a DC
input/output regulator.
28. An impressed current cathodic protection system according to
claim 27 wherein the system is capable of operating at a number of
output capacity ranges.
29. An impressed current cathodic protection system according to
according to claim 28 wherein the system is capable of operating at
about 50, 150, 500 and 1000 mA.
30. An impressed current cathodic protection system according to
claim 27 wherein the input/output regulator and control circuitry
are designed to fit within a small control box which may be fitted
on the structure or support column or, where applicable, on a
structure within close proximity.
31. An impressed current cathodic protection system according to
claim 1 wherein the system is optionally provided with lightning
and surge protection.
32. An impressed current cathodic protection system according to
claim 1 wherein the system is optionally provided with monitoring
systems.
33. An impressed current cathodic protection system according to
claim 1 wherein the system is optionally provided with one or more
permanently installed reference cells to allow monitoring of the
protection system by conventional manual methods or via an
electronic interface or SCADA system.
34. An impressed current cathodic protection system according to
claim 1 wherein the system is optionally provided with a remote
electronic surveillance and monitoring system to provide continuous
electronic monitoring and reporting via satellite or a GSM
communications system.
35. An impressed current cathodic protection system according to
claim 1 wherein the system is optionally provided with a remote
automatically controlled input/output regulated system.
36. A method of operating an impressed current cathodic protection
system by means of the apparatus disclosed herein with reference to
the description and drawings.
37. A method of operating an impressed current cathodic protection
system by means of the apparatus disclosed herein in which the
total CO.sub.2 footprint for the 1.5 mm diameter MMO/TiO.sub.2
anode will be about 0.473 kgs/m
38. A method of operating an impressed current cathodic protection
system by means of the apparatus disclosed herein with reference to
the description and drawings.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a cathodic protection system for
steel structures (or cast iron) structures. This invention has
particular application for cathodic protection of buried and
submerged structures (on land and in marine off-shore
applications). However, it is also be relevant for other types of
structures in which steel (or iron) is a significant structural
component.
BACKGROUND OF THE INVENTION
[0002] Steel structures are used widely in industrial structures
and infrastructure due to its strength and tensile properties.
However, corrosion is a major problem over time. The use of
cathodic protection (CP) using sacrificial anode systems in order
to inhibit corrosion of these structures is well known.
Conventional sacrificial anode systems are fitted to industrial
structures such as pipelines, above ground storage tanks,
underground tanks, and many other structures sited on or buried in
the ground. Typically, this is done by attaching a number of metal
blocks (anodes) of a more active metal such as magnesium to the
steel structure. The more active metal acts as a sacrificial anode
preferentially corroding away. This generates a small amount of DC
current. The current output capacity of a magnesium sacrificial
anode system attached to a pipeline or similar structure is
normally 50 mA or less. However, for poorly coated pipelines or
structures, anode systems as high as 1500 mA or greater can be
required.
[0003] Magnesium anodes are very inefficient. In order to generate
100 mA of current, one kilogram of magnesium alloy is consumed per
year. 55% of consumption produces the DC current. The remaining 45%
of the corrosion is consumed by self corrosion of the magnesium
metal. Accordingly, the electrical efficiency of the anode is only
around 55%. If the anode were disconnected from the steel
structure, it would still naturally waste away due to self
corrosion.
[0004] In order to achieve the DC current output required for
corrosion protection, it is often necessary to fit a number of
anodes at any one location. For a buried pipeline, anode beds are
typically installed at two to four kilometre intervals at a
distance of not more than two metres from the pipeline easement. A
typical anode bed is comprised of 5 or more anodes in order to
generate the requisite current at the installation location.
Typically, the primary cost for five sacrificial anodes will be in
the order of AUD$2,000.00. The installation and commissioning costs
of the anode bed including civil works and commissioning will
typically be in the order of AUD$5,000.00.
[0005] A typical magnesium sacrificial anode system has a life
expectancy of ten years. Because many sacrificial anode systems are
installed on pipelines often in congested city streets and have to
be installed close to the pipelines. With urban development, the
cost to excavate and install new anode beds on a ten year cycle is
significantly higher. Replacement costs plus extensive excavation
costs in congested urban areas can be in the order of at least
AUD$10,000 per site. For installations along a pipeline route,
being installed every two to four kilometers, the accumulated
replacement costs over a fifty year lifecycle of a pipeline can be
in the hundreds of thousands of dollars.
[0006] The cost to the environment in producing 1 kg of magnesium
is approximately 40 kJ of power. So, apart from being a very
inefficient anode material, the carbon footprint to the environment
is grossly unacceptable. The environmental efficiency of a material
is largely determined by the CO.sub.2 footprint.
[0007] CO.sub.2 Footprint:
[0008] The production of 1 kg of magnesium generates a CO.sub.2
footprint of 42 kg of CO.sub.2. The annual average magnesium
tonnage consumed by the cathodic protection industry per annum in
Australia and New Zealand alone is in excess of 400 tonnes. This
equates to an annual CO.sub.2 footprint of 16,800 tonnes of
CO.sub.2. Assuming a cost of AUD$23.00 per tonne for CO.sub.2, this
equates to an annual cost to industry before materials of $386,400.
Over a fifty year design life, this equates to a CO.sub.2 cost of
AUD$19,320,000.00 (being close to AUD$20,000,000. The environmental
efficiency of a material substitution is largely determined by the
CO.sub.2 footprint.
SUMMARY OF THE INVENTION
[0009] There is disclosed herein an impressed current cathodic
protection system for a target structure susceptible to corrosion
(such as of steel or cast iron) which comprises an inert mixed
metal oxide (hereinafter referred to as "MMO") anode surrounded by
a tightly packed conductive zone connected to a power supply source
and having an input/output regulator to control the flow of current
to the target structure. Preferably, the tightly packed conductive
zone is in the form of a powder. In the preferred embodiment the
tightly packed conductive zone is comprised of calcined petroleum
coke (semi graphitized carbon particles). Further, in the preferred
embodiment, the system is driven by a DC power supply stored in a
sealed battery cell.
[0010] A number of conventional anode materials were considered for
this application and rejected. Silicon, iron (chromium), graphite
and scrap steel were all potential materials but considered
unlikely to have the desired life expectancy for the application.
Platinised titanium has/had historical technical limitations on
voltage. Platinised niobium was not cost competitive. As the life
of the anode is critical for cathodic protection, it was decided
that MMO was currently the best available material for this
application. An MMO electrode is one in which the surface contains
two or more kinds of metal oxides. One of the metals, usually one
or more earth derivatives (such as RuO.sub.2, IrO.sub.2, or
PtO.sub.0.12 conducts electricity and catalyzes the reaction. The
amount of this (more expensive) metal is up to 10-12 g per square
metre. The other metal is typically in the form of TiO.sub.2 which
does not conduct or catalyze the reaction, but prevents corrosion
of the interior (and is cheaper). The interior of the MMO electrode
is typically made of titanium. The MMO coating is applied to the
surface of the titanium substrate to activate the surface.
[0011] According to the system of the present invention, the anode
is surrounded by a zone of calcined petroleum coke, being a highly
conductive material. This is in the form of a tightly packed powder
with a low moisture content. This provides a tightly packed
conductive zone around the anode and effectively increases the
active zone of the anode.
[0012] According to one form of the invention, the specification
for the calcined petroleum coke is as follows:
[0013] Fixed carbon: 99.35%
[0014] Ash: 0.6%
[0015] Moisture: 0.05%
[0016] Volatiles: Nil at 950.degree. C.
[0017] Bulk Density: 74 lbs. per cubic foot.
[0018] Predominantly round particles.
[0019] All particles surface modified for maximum electrical
conductivity.
[0020] Particle Sizing: Dust free with a maximum particle size of 1
mm.
[0021] Minimum calcination temperature of base materials in excess
of 1200.degree. C.
[0022] Base materials calcined under ISO 9002 quality control.
[0023] Surfactants added to assist pumping and settling.
[0024] No de-dusting oils used during the manufacture of base
particles.
[0025] This material was selected as it exhibited the best
electrical properties and reliability under the conditions
tested.
[0026] In a preferred form of the invention, the anode and
surrounding zone of calcined petroleum coke is contained within a
tubular sleeve which is sealed at both ends. The sleeve may be of a
permeable synthetic or linen cloth, or other suitable material,
which is non-degradable in the environment in which the anode is to
be used. The MMO wire is located along the centre of the sleeve
which is sealed at one end. The calcined petroleum coke backfill is
air blown into the sleeve through the other end and then sealed.
The sleeve which by way of example may be typically (approx 50 mm
Diameter.times.2000 mm and approximately 2 kg in weight) is of a
compact design and allows for ease of installation. This is
particularly important in congested urban areas where a more
compact system is required.
[0027] The system is designed to be able to produce 50 to 150 mA of
current subject to suitable conditions (such as soil resistivity).
The number of anodes required to achieve the desired life
expectancy will vary from one to a number of anodes depending upon
the soil resistivity. Typically, a number of anodes are placed into
a bed. The placement of the anode bed will be determined by a range
of factors such as safe burial offset or below pipe distances and
soil resistivity.
[0028] In certain circumstances, where a greater level of
currentlife expectancy is required, it is possible to effectively
increase the capacity of the system by adding more calcined
petroleum coke. This may be achieved by using a larger sleeve or by
adding calcined petroleum coke to the anode bed excavation
(provided that the coke is sufficiently tightly compacted so that
the entire bed becomes a working anode bed).
[0029] According to a preferred form of the invention, the system
is provided with solar input power generation and battery storage.
The batteries are charged by solar powered cells or panels. These
may be mounted by various means. These may be mounted on the
structure itself or in the case of a pipeline on a column designed
for this purpose which may also conveniently house the hardware and
service access.
[0030] It is anticipated that other alternative forms of
environmentally friendly or cost effective forms of power supply
may be utilized. These may include wind, thermo electric generators
(TEGs) or turbine generation.
[0031] The use of solar or other environmentally friendly forms of
power generation and storage provides a long-life system with
environmentally favourable power generation thereby minimizing the
environmental impact. It is anticipated that the total CO.sub.2
footprint for the 1.5 mm diameter MMO/TlO.sub.2 anode will be
around 0.473 kgsm.
[0032] The output power to the structure is controlled by a DC
input/output regulator. Preferably, the system will be capable of
operating at a number of output capacity ranges. Typically, these
would be 50, 150, 500 and 1000 mA. However, these figures are by
way of example only. The range may vary depending upon the
application. Preferably, this would also be provided with lightning
and surge protection. Typically, the output regulator is
approximately 30 mm.times.80 mm. The output regulator and control
circuitry are designed to fit within a small control box which may
be fitted on the structure or support column or, where applicable,
on a structure within close proximity such as a suburban
lamppost.
[0033] The system design can also accommodate a range of optional
monitoring systems.
[0034] The system can accommodate the inclusion of a permanently
installed reference cell to allow monitoring of the protection
system by conventional manual methods or via an electronic
interface or SCADA system.
[0035] Alternatively, the system can accommodate remote electronic
surveillance and monitoring systems to provide continuous
electronic monitoring and reporting via satellite or a GSM
communications system. Accordingly, the system is capable of
reducing the need to travel to sites for inspection and
testing.
[0036] Alternatively, the system can also accommodate an
automatically controlled output regulated system that incorporates
the above reference cells. This may be set during commissioning to
allow for a set protection level and also regulates output in
automatic control mode.
[0037] The above system utilizes inert anodes that do not
galvanically corrode and increases the active zone of the anode,
thus greatly increasing the life expectancy of the system over
those systems currently known and in use. It is anticipated that
the system of the present invention will have a life of at least 50
years. To accord with the anticipated life expectancy, the anode
bed, electronics and related electrical components are also all
designed to a specification of at least a 50 year life expectancy.
The advantage of the above invention over current systems is that
it provides a compact system with a 50 year life expectancy which
is easy to install even in difficult conditions. It is also able to
be modified so as to provide a level of flexibility.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] In order that this invention may be more readily understood
and put into practical effect, a preferred form of the present
invention will now be described by way of example with reference to
the accompanying drawings wherein:
[0039] FIG. 1 is a cross-sectional view of a preferred embodiment
of the impressed current cathodic protection system.
[0040] FIG. 2 is a cross-sectional elevational view of a further
preferred embodiment of the system of the present invention showing
a solar powered impressed current cathodic protection system and
reference cell installation.
[0041] FIG. 3 is a cross-sectional side view of the embodiment in
FIG. 2.
[0042] FIG. 4 is a detailed front elevational view of the solar
panel and supporting column, foundation for the solar powered
installation in FIGS. 2 and 3 and of the housing for the regulator
and control circuitry.
[0043] FIG. 5 is a further detailed front elevational view of the
solar panel, supporting column, foundation and baseplate for the
solar powered installation in FIGS. 2 and 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] Referring to FIG. 1, there is shown an impressed current
cathodic protection system for steel (& cast iron?) structures
(1) which comprises an inert mixed metal oxide (MMO) anode wire (2)
surrounded by a zone of calcined petroleum coke (3) contained
within a tubular sleeve (4) sealed at both ends (5) and connected
via a cable tail (6) to a power supply. Preferably, the system is
driven by a DC power supply, which in this embodiment is a sealed
battery cell (not shown).
[0045] The system also has an output regulator (not shown) to
control the flow of current to the target structure.
In this preferred form of the invention, the specification for the
calcined petroleum coke is as follows:
[0046] Fixed carbon: 99.35%
[0047] Ash: 0.6%
[0048] Moisture: 0.05%
[0049] Volatiles: Nil at 950.degree. C.
[0050] Bulk Density: 74 lbs. per cubic foot.
[0051] Predominantly round particles.
[0052] All particles surface modified for maximum electrical
conductivity.
[0053] Particle Sizing: Dust free with a maximum particle size of 1
mm.
[0054] Minimum calcination temperature of base materials in excess
of 1200.degree. C.
[0055] Base materials calcined under ISO 9002 quality control.
[0056] Surfactants added to assist pumping and settling.
[0057] No de-dusting oils used during the manufacture of base
particles.
[0058] This material was selected as it exhibited the best
electrical properties and reliability under the conditions
tested.
[0059] Referring to FIGS. 2 & 3, there is shown an elevational
and side view respectively of a further preferred embodiment of the
cathodic protection system (which may be comprised of one or a bed
of anodes) of the present invention. FIGS. 2 and 3 show the
placement of the cathodic protection system (1) and a reference
cell (7) relative to pipeline (8), being the target structure in
this case. The cathodic protection system (1) and reference cell
(7) are embedded in sand (9) at a safe burial distance from the
pipeline (8). This is covered by a layer of rock/free backfill (10)
and generally topped with a finished grade (11). In this
embodiment, the system is provided with solar input power
generation. The cathodic protection system is connected by cables
(12) to one or more batteries. The batteries are charged by solar
cells on one or more solar panels (13). These are mounted on a
supporting column (14) with baseplate (15) in concrete foundation
(15). The output regulator, control circuitry and service access
are located in housing (17) at the base of the column (14) with
access door (18) for ease of access. A detailed view of the column
(14), foundation (16), housing (17) and baseplate (15) are provided
in FIG. 4. Structural components and related equipment are
manufactured to applicable local building and safety standards.
[0060] In other forms of the invention, it is envisaged that other
alternative forms of environmentally friendly or cost effective
forms of power supply may be utilized. These may include wind, TEGs
or turbine generation.
[0061] It will of course be realized that while the foregoing has
been given by way of illustrative example of this invention, all
such and other modifications and variations thereto as would be
apparent to persons skilled in the art are deemed to fall within
the broad scope and ambit of this invention as is herein set
forth.
* * * * *