U.S. patent application number 15/972609 was filed with the patent office on 2018-08-30 for device for thermal ablation of pigging devices.
The applicant listed for this patent is SPT GROUP LLC. Invention is credited to James R. Collins, Andrew J. Pounds, Mark S. Sankey, William Scott Stalnaker, James F. Stewart, Dennis Aubrey Walker, John Rodney Walker.
Application Number | 20180243752 15/972609 |
Document ID | / |
Family ID | 57601972 |
Filed Date | 2018-08-30 |
United States Patent
Application |
20180243752 |
Kind Code |
A1 |
Sankey; Mark S. ; et
al. |
August 30, 2018 |
Device for Thermal Ablation of Pigging Devices
Abstract
The present disclosure provides for a novel pig design and
method of retrieval based on thermal ablation. The pig comprises an
external layer and an inner core, where the inner core further
comprises at least one incendiary charge comprising at least one
exothermic material. When ignited via an ignition source, the
incendiary charge releases the exothermic material into one or more
thermal dispersion channels. The exothermic material melts the
interior of these thermal dispersion channels thereby distributing
the exothermic material throughout the pig device causing its
destruction via thermal ablation. The destroyed pig can then be
easily retrieved from its location in a pipe, as detected via radio
signals, without the need for costly excavation of large sections
of the pipe.
Inventors: |
Sankey; Mark S.;
(Washington, PA) ; Stewart; James F.; (Lafayette,
AL) ; Pounds; Andrew J.; (Macon, GA) ;
Stalnaker; William Scott; (Butler, GA) ; Walker; John
Rodney; (Macon, GA) ; Walker; Dennis Aubrey;
(Macon, GA) ; Collins; James R.; (Jackson's Gap,
AL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SPT GROUP LLC |
Washington |
PA |
US |
|
|
Family ID: |
57601972 |
Appl. No.: |
15/972609 |
Filed: |
May 7, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15788633 |
Oct 19, 2017 |
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15972609 |
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15187866 |
Jun 21, 2016 |
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15788633 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16L 55/40 20130101;
F16L 55/48 20130101; B02C 19/186 20130101; F16L 55/46 20130101 |
International
Class: |
B02C 19/18 20060101
B02C019/18; F16L 55/48 20060101 F16L055/48; F16L 55/40 20060101
F16L055/40; F16L 55/46 20060101 F16L055/46 |
Claims
1. A pig device comprising: an external layer; and an inner core,
wherein the inner core further comprises: at least one incendiary
charge wherein each incendiary charge further comprises at least
one exothermic material; at least one ignition source coupled to
each incendiary charge wherein each ignition source is configured
so as to ignite the associated incendiary charge; a plurality of
thermal dispersion channels arranged within the inner core; and at
least one switching mechanism configured so as to activate the
ignition source.
2. The pig device of claim 1 wherein the external layer further
comprises an abrasive-resistant cover.
3. The pig device of claim 1 further comprising at least one of an
abrasive coating and a brush.
4. The pig device of claim 1 wherein the thermal channels are
further filled with paraffin wax wherein the paraffin wax further
melts upon ignition of the incendiary charge to thereby provide for
uniform thermal propagation for the ablation process.
5. The pig device of claim 1 wherein the switching mechanism
further comprises at least one of: a manual hardwired switching
mechanism, a manual radio controlled switching mechanism, and an
automatic pressure sensing switching mechanism.
6. The pig device of claim 1 wherein at least one of the external
layer and the inner core further comprise at least one polyurethane
material.
7. The pig device of claim 1 further comprising at least one radio
receiver configured for signaling the location of the pig device
inside a pipeline.
8. The pig device of claim 1 further comprising at least one power
source.
9. The pig device of claim 8 wherein the power source further
comprises one or more batteries.
10. The pig device of claim 1 wherein the exothermic material
further comprises at least one of: barium nitrate, barium sulfate,
iron (III) oxide, aluminum, and magnesium.
11. The pig device of claim 10 wherein the exothermic material
further comprises barium nitrate in amounts of about 22.5% to about
27.5% by mass; barium sulfate in amounts of about 25.3% to about
33.5% by mass; iron (III) oxide in amounts of about 14.8% to about
19.4% by mass; aluminum in amounts of about 12.8% to about 15.8% by
mass; and magnesium in amounts of about 10.4% to about 13.5%.
12. The pig device of claim 1 wherein the exothermic material is
further housed in one or more materials.
13. The pig device of claim 1 further comprising at least one
secondary ignition material operably coupled to the exothermic
material to aid in the ignition of the incendiary charge.
14. The pig device of claim 1 further comprising at least one
pyrotechnic igniter operably coupled to either the secondary
ignition material or the exothermic material to aid in the ignition
of the incendiary charge.
15. A pig device comprising: at least one radio receiver configured
for signaling the location of the pig device inside a pipeline; at
least one power source comprising one or more batteries; at least
one of an abrasive coating and a brush; at least one secondary
ignition material operably coupled to the exothermic material to
aid in the ignition of the incendiary charge; and at least one
pyrotechnic igniter operably coupled to either the secondary
ignition material or the exothermic material to aid in the ignition
of the incendiary charge an external layer, wherein the external
layer further comprises an abrasive-resistant cover; an inner core,
wherein at least one of the external layer and the inner core
further comprise at least one polyurethane material, and wherein
the inner core further comprises: at least one incendiary charge
wherein each incendiary charge further comprises at least one
exothermic material housed in one or more materials, wherein the
exothermic material further comprises at least one of: barium
nitrate, barium sulfate, iron (III) oxide, aluminum, and magnesium,
at least one ignition source coupled to each incendiary charge
wherein each ignition source is configured so as to ignite the
associated incendiary charge, a plurality of thermal dispersion
channels arranged within the inner core, wherein the thermal
channels are further filled with paraffin wax wherein the paraffin
wax further melts upon ignition of the incendiary charge to thereby
provide for uniform thermal propagation for the ablation process,
and at least one switching mechanism configured so as to activate
the ignition source wherein the switching mechanism further
comprises at least one of: a manual hardwired switching mechanism,
a manual radio controlled switching mechanism, and an automatic
pressure sensing switching mechanism.
16. The pig device of claim 15 wherein the exothermic material
further comprises barium nitrate in amounts of about 22.5% to about
27.5% by mass; barium sulfate in amounts of about 25.3% to about
33.5% by mass; iron (III) oxide in amounts of about 14.8% to about
19.4% by mass; aluminum in amounts of about 12.8% to about 15.8% by
mass; and magnesium in amounts of about 10.4% to about 13.5%.
17. A pig device comprising: at least one radio receiver configured
for signaling the location of the pig device inside a pipeline; an
external layer; inner core wherein at least one of the external
layer and the inner core further comprise at least one polyurethane
material; and wherein the inner core further comprises: at least
one incendiary charge wherein each incendiary charge further
comprises at least one exothermic material housed in one or more
materials, wherein the exothermic material further comprises at
least one of: barium nitrate, barium sulfate, iron (III) oxide,
aluminum, and magnesium, at least one ignition source coupled to
each incendiary charge wherein each ignition source is configured
so as to ignite the associated incendiary charge, a plurality of
thermal dispersion channels arranged within the inner core wherein
the thermal channels are further filled with paraffin wax wherein
the paraffin wax further melts upon ignition of the incendiary
charge to thereby provide for uniform thermal propagation for the
ablation process, and at least one switching mechanism configured
so as to activate the ignition source wherein the switching
mechanism further comprises at least one of: a manual hardwired
switching mechanism, a manual radio controlled switching mechanism,
and an automatic pressure sensing switching mechanism.
18. The pig device of claim 17 further comprising: wherein the
exothermic material further comprises barium nitrate in amounts of
about 22.5% to about 27.5% by mass; barium sulfate in amounts of
about 25.3% to about 33.5% by mass; iron (III) oxide in amounts of
about 14.8% to about 19.4% by mass; aluminum in amounts of about
12.8% to about 15.8% by mass; and magnesium in amounts of about
10.4% to about 13.5%.
Description
RELATED APPLICATIONS
[0001] This Application is a continuation of pending U.S. patent
application Ser. No. 15/788,633, filed on Oct. 19, 2017, entitled
"Device for Thermal Ablation of Pigging Devices," which itself is a
continuation of pending U.S. patent application Ser. No.
15/187,866, filed on Jun. 21, 2016, entitled "System and Method for
Thermal Ablation of Pigging Devices," which itself claims priority
under 35 U.S.C. .sctn.119(e) to pending U.S. Provisional Patent
Application No. 62/184,981, filed on Jun. 26, 2015, entitled
"System and Method for Thermal Ablation of Pigging Devices." These
applications are hereby incorporated by reference in their
entireties.
BACKGROUND
[0002] Pigging is used as a mechanism to clean internal surfaces of
pipelines including sewer, process, water, wastewater and other
types of pipes. Pigging is used to reduce the friction losses of
pumping energy, improve flow rates of restricted piping, and as a
general maintenance process. Typical materials of construction for
water pipe and municipal, commercial, and industrial sewer pipe
include ductile iron, polyvinyl chloride ("PVC"), and lined ductile
iron or cast iron pipe. As sewer force mains are used over time,
the flow of sewage is restricted by a buildup of restricting
materials on the inside of the pipe. This material includes solid
waste, grease, pipe corrosion and other materials. In addition to
these restrictions, force sewer mains, which were installed years
and sometimes generations ago, are used to carry flow in excess of
their original design capacity. As the pipe is restricted over
time, the pumping horsepower requirement increases, flow is
reduced, and electrical energy consumption of the pump is
increased.
[0003] Pigging is the process of inserting a device (known
commercially as a pig) into the pipe through an insertion point
installed at a particular location in the pipe. The insertion point
is generally referred to as a launch station, and includes an array
using a tee, valving, and a pressure injection point to allow the
pig to be inserted into the pipe and then propelled through the
pipe via motive force which may be water, steam or compressed air.
Once inserted, the pig is propelled through the length of pipe,
which is typically underground, to a designated removal point.
While traversing the pipe the pig scours the inner wall of the
pipe, without damaging the pipe, to remove any flow restricting
material.
[0004] Pig construction is generally of polyurethane foam, with or
without an abrasion resistant cover. Alternate pig materials of the
prior art include Styrofoam, polypropylene, and ice. Various
abrasive coatings may also be used and brushes may be adhered or
fastened to the bearing surfaces (where the pig is in contact with
the pipe wall). These abrasive coatings and brushes aid the pig in
clearing debris from the interior of the pipe.
[0005] Currently, pigging utilizes a process of progressive
pigging, wherein several pigs of varying diameters, all being
smaller in overall outside diameter than the nominal inside
diameter of the pipe, are used to insure that no obstruction which
would cause the pig's progress though the pipe to be impeded to the
point of the pig being stalled or stuck in the pipe. Once a smaller
diameter pig has successfully traversed the length of pipe being
cleaned, a slightly larger pig is inserted, and the process
repeated until near nominal internal pipe diameter is reached, or
obstruction of the pipe becomes a risk. During the pigging process
the pressure of the propulsion medium is monitored continuously. So
long as the pig is traveling through the pipe, the pressure remains
at a constant level, plus or minus a predetermined tolerance. As
fluid or gas is injected into the pipe, the pig travels through the
pipe increasing the effective volume filled by the propulsion
media, resulting in relatively constant pressure. If the pig
movement stops, the volume behind the pig within the pipe no longer
increases, and as propulsion material is added the pressure within
the pipe will rise rapidly.
[0006] A stalled or stuck pig represents a significant technical
and logistical problem. The overwhelming majority of wastewater and
sewage piping is installed underground. Based on the age and
location of the pipe, as well as potential interference with other
utility piping, the effect on other electrical and
telecommunication utilities by a stuck or stalled pig is largely
unknown. Even in a scenario where the exact pipe location is
documented, the exact pig location within the pipe may still be
unknown.
[0007] As a result, the location and retrieval of a stalled pig can
be incredibly costly. Often, the retrieval requires a utility
shutdown, a diversion of sewage via multiple vacuum trucks at
sewage interceptors, and coordination with municipal and utility
entities to divert traffic flow and coordinate utility shutdowns
while excavation and removal of the stuck pig occurs. In such a
case, the only method to remove a stalled pig is to begin
excavating the pipe. Due to the fact that the exact location of the
stuck pig is unknown, multiple excavations may be required until
the exact location of the stalled pig is determined and successful
removal of the pig is achieved.
[0008] As an alternative to progressive pigging, and in an attempt
to mitigate the risk and cost of a stalled or suck pig, a process
of pigging has been modified to use pigs made of ice or gelatin.
Pigs made of these materials will degrade and break down as the pig
travels the length of the pipe. This modification substantially
eliminates the risk of a stalled pipe since the pig will melt or
erode as it passes through the pipe. Pigs made of ice will continue
to melt even after the pig becomes stalled or stuck in the pipe.
The erosive nature of pigs made of these materials often eliminates
the problem with no need for excavation of the pipe or other
remedial action. Unfortunately, the overall dimension of the ice or
gelatin pig begins to decrease as soon as the pig is inserted into
the pipe. As the pig traverses the length of the pipe, the
reduction in overall dimension continues, resulting in a reduction
in effectiveness of the ice or gelatin pig as the pig travels the
length of the pipe. Ultimately, use of an ice or gelatin pig for
long distance pigging is of very little if any benefit.
[0009] There exists a need for a novel pig design that
substantially reduces the risk of the pig being stuck or stalled in
a pipe and which can be retrieved without substantial additional
risk or cost. It would also be advantageous if the novel pig design
improved and maintained the effectiveness of the pig as it travels
the length of the pipe, thereby improving current methods for
pigging of long distance pipelines.
SUMMARY OF THE INVENTION
[0010] The present disclosure provides for a novel pig design and
retrieval method based on thermal ablation. The pig is constructed
with a correctly engineered incendiary charge corresponding to the
size, density, and the materials of construction of both the pig
and the pipe in which the pig will be used. The incendiary charge
is correctly sized so that the pig is sufficiently destroyed upon
ignition to allow any remaining components or residue in the pipe
to be passed through the pipe without the need to excavate the pipe
to retrieve the pig. The pig may be designed to be destroyed
automatically, manually, or by a combination of automatic control
with manual override of the incendiary charge.
[0011] In one embodiment, the present disclosure provides for a pig
device comprising an external layer and an inner core made of
polyurethane foam. The inner core may further comprise at least one
incendiary charge wherein each incendiary charge further comprises
at least one exothermic material. At least one ignition source may
be coupled to each incendiary charge and be configured so as to
ignite the associated incendiary charge. A plurality of thermal
dispersion channels may be arranged in the inner core to enable the
exothermic material to evenly propagate through the pig device and
cause its destruction. One or more switching mechanisms may be
configured to control the activation of the ignition source thereby
controlling the release of the exothermic material through the pig
device.
[0012] In another embodiment, the present disclosure provides for a
method for thermally ablating a pig device. This method may
comprise providing a pig device comprising an external layer and an
inner core, wherein the inner core comprises one or more incendiary
charges and wherein each incendiary charge further comprises one or
more exothermic materials. The ignition source, which is operably
coupled to an incendiary charge, may be ignited, to thereby release
the exothermic material into one or more thermal dispersion
channels. The interior of each thermal dispersion channel is melted
to thereby disperse the exothermic material through the inner core
and thereby destroy the pig device.
[0013] In another embodiment, the present disclosure provides for a
method for retrieving a pig device which is destroyed using thermal
ablation. The method may comprise first locating the pig device
within a pipeline by detecting radio signals emitted by a radio
receiver located within the pig device. Once the pig device has
been located, the method may further comprise igniting at least one
ignition source, wherein each ignition source is operably coupled
to an incendiary charge, to thereby release at least one exothermic
material into one or more thermal dispersion channels. The interior
of each thermal dispersion channel is melted to thereby disperse
the exothermic material through the inner core of the pig device
and thereby destroy the pig device. The destroyed pig may then be
easily retrieved at its detected location.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings, which are included to provide
further understanding of the disclosure and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the disclosure and, together with the description, serve to explain
the principles of the disclosure.
[0015] In the drawings:
[0016] FIG. 1 is representative of a pig of the present
disclosure.
[0017] FIG. 2A is representative of a side view of a pig of the
present disclosure.
[0018] FIG. 2B is representative of a front view of a pig of the
present disclosure.
[0019] FIG. 3A is representative of a side view of the switching
mechanisms and charge configurations of the pig device of the
present disclosure.
[0020] FIG. 3B is representative of a front view of the switching
mechanisms and charge configurations of the pig device of the
present disclosure.
[0021] FIG. 4 is representative of a method of the present
disclosure.
[0022] FIG. 5 is representative of a method of the present
disclosure.
[0023] FIG. 6 is representative of a base of a pig device of the
present disclosure with an inner core made of polyurethane
foam.
[0024] FIG. 7 is representative of an incendiary charge used in a
pig of the present disclosure with two igniters.
[0025] FIG. 8 is representative of a pig device loaded with an
incendiary charge.
[0026] FIG. 9 is representative of a pig device loaded with a radio
receiver.
[0027] FIG. 10 is representative of a pig device ablated using the
methods described herein.
[0028] FIG. 11 is representative of a pig device ablated using the
methods described herein.
[0029] FIG. 12 is a thermal image illustrating heat emitted by a
pig device during ablation.
[0030] FIG. 13 is a thermal image illustrating heat emitted by a
pig device during ablation.
[0031] FIG. 14 is a thermal image illustrating heat emitted by a
pig device during ablation.
[0032] FIG. 15 is representative of a pig device of the present
disclosure inserted into an exemplary pipe during testing.
[0033] FIGS. 16A-16C illustrates the dimensions of a rock used as
an obstruction in experimental designs used to test the
effectiveness of a pig device of the present disclosure. FIG. 16A
shows the width of the rock obstruction as being approximately four
inches. FIG. 16B shows the length of the rock obstruction as being
approximately seven inches and FIG. 16C shows the height of the
rock obstruction as being approximately 2.5 inches.
[0034] FIG. 17 is representative of a pig device of the present
disclosure inserted into an exemplary pipe during testing showing
an obstruction.
[0035] FIG. 18 is representative of a pig device of the present
disclosure inserted into an exemplary pipe during testing showing
an obstruction.
[0036] FIG. 19 is representative of a pig device of the present
disclosure inserted into an exemplary pipe during testing showing
an obstruction.
[0037] FIG. 20 is representative of the interior of a pipe after
ablation of a pig device using the methods described herein.
DETAILED DESCRIPTION
[0038] Reference will now be made in detail to the preferred
embodiments of the present disclosure, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0039] The pig device of the present disclosure overcomes the
limitations of the prior art by providing a novel design for easy
location, destruction, and retrieval of the pig using thermal
ablation techniques. Referring to FIG. 1, the pig device 100 may
comprise an external layer 110 and an inner core 115. In one
embodiment, both the external layer 110 and the internal core 115
may comprise a polyurethane foam material. Constructing the pig
device 100 using a polyurethane material is advantageous over the
designs of the prior art that use materials such as gelatin or ice.
Where pigs constructed using gelatin or ice degrade as the pig
travels the length of a pipe, the polyurethane pig of the present
disclosure maintains it size, and therefore its efficacy, until it
is deflagrated in accordance with the methods disclosed herein. The
external layer 110 may further comprise an abrasive-resistant cover
configured to protect the pig device from damage as it travels the
length of a pipe and one or more abrasive coatings or brushes
configured to clear debris from interior of the pipe.
[0040] Referring again to FIG. 1, the pig device 100 may comprise
at least one incendiary charge 120a where each incendiary charge
comprises one or more exothermic materials. When the incendiary
charge 120a is ignited by an ignition source, the exothermic
materials are released into a plurality of thermal dispersion
channels 125a-125d. The thermal dispersion channels are designed so
as to prevent water or other materials from entering the inner core
of the pig device and disrupting or preventing the ignition
process. In one embodiment, thermal dispersion channels 125a-125d
may be filled with a material, such as paraffin wax, which melts
upon the ignition of the incendiary charge and provides channels
for the exothermic material to evenly disperse through the pig
device. This dispersion of the exothermic material causes the pig
device to deflagrate so that it can be easily retrieved from the
pipe. In other embodiments, any hydrophobic material with a low
melting point may be used to fill the thermal dispersion channels.
One example of a material that may be used as an alternative to
paraffin wax is heavy grease. The thermal dispersion channels may
also be left unfilled. In such an embodiment, the ends of these
thermal dispersion channels may be plugged with a room temperature
vulcanizing sealant to prevent water and other materials from
entering the inner core.
[0041] Ignition of the incendiary charge 120a may be achieved via
one or more switching mechanisms 130. These switching mechanisms
are known in the art and may include at least one of: a manual
hardwired switching mechanism, a manual radio controlled switching
mechanism, and an automatic pressure sensing switching mechanism.
An exemplary design of the switching mechanism 130 is illustrated
in more detail in FIG. 3A and FIG. 3B. FIG. 3A is representative of
a side view of the various charges and switching mechanisms
contemplated by the present disclosure while FIG. 3B is
representative of a front view of these various mechanisms. While
the embodiment of FIG. 3A and FIG. 3B illustrate the pig device 100
as comprising all three switching mechanisms, it is noted that not
all three switching mechanisms are required and other embodiments
may utilize only one or two of the illustrated switching
mechanisms. A manual hardwired switching mechanism 130a may be used
to fire the pig device 100 via tether wire connected directly to
the pig firing controls and fed into the pipe via a wire reel setup
at the launch station. This firing control configuration is best
suited as a manual backup to the automatic firing control system
which may be onboard the pig. Best applications for this switching
mechanism include firing in a deeply buried or extremely long pipe
where the approximate location of the pig may be difficult to
determine. This manual hardwired switching mechanism 130a is also
useful for ablating a pig located within a ductile iron pipe which
is impervious to radio frequency signals.
[0042] A manual radio controlled switching mechanism 130b may be
used to fire the pig device 100 via a remote control with a radio
receiver mounted on board the pig. In one embodiment, the radio
receiver may comprise an attendant 9 volt battery. Manual radio
remote control firing alone is applicable to scenarios where
adequate pressure control and regulation is not available or
practical, or pipe distance is relatively short, allowing the
operator the ability to walk the length of the pipe, generating
multiple ignition requests.
[0043] A pressure sensing switching mechanism 130c may be used to
fire the pig device 100 by sensing when a set pressure has been
reached. For example when the pressure on the pressure sensing
switching mechanism 130c reaches a specified level due to a
propulsion material added to the pipe, the switch will close an
electrical contact and cause the incendiary charge 120a to fire.
Igniters 127a-127e may be wired in parallel and operably coupled to
the incendiary charge 120a and function to ignite the incendiary
charge 120a. As can be seen in FIG. 3A and FIG. 3B, these igniters
127a-127e may be placed at various locations around the incendiary
charge 120a. A radio receiver, to locate the pig device 100 within
a pipe, and radio receiver and power source 135 may also be located
with in the inner core 115 of the pig device 100. In one
embodiment, the power source 135 may comprise one or more
batteries.
[0044] FIG. 2A and FIG. 2B are illustrative of another embodiment
of the pig device 100 of the present disclosure. As seen in FIGS.
2A and 2B, the pig device 100 comprises a plurality of incendiary
charges 120a-120h configured in a circular arrangement (which can
be seen from the front view of the pig device 100 in FIG. 2B) in
the inner core 115. It is noted that any number and any arrangement
of the incendiary charges may be used based on the size of the pig
device 110 as necessary to achieve the ablation of the pig device
100. As seen in FIG. 2A each incendiary charge 120a-h is coupled to
a thermal dispersion channel 125a-125h to ensure the exothermic
material is evenly distributed throughout the pig device 100. This
coupling between each incendiary charge 120a-h and the thermal
dispersion channels 125a-125h is further illustrated in FIG.
2B.
[0045] The present disclosure also provides for a method for
thermally ablating a pig device, one embodiment of which is
illustrated in FIG. 4. The method 400 may comprise providing a pig
device comprising an external layer and an inner core, wherein the
inner core comprises one or more incendiary charges and wherein
each incendiary charge further comprises one or more exothermic
materials in step 410. An ignition source, operably coupled to each
incendiary charge, may be ignited in step 420 to thereby release
the exothermic material into one or more thermal dispersion
channels. The interior of each thermal dispersion channel is melted
in step 430 by the exothermic material which enables the exothermic
material to propagate through the pig device thereby destroying it
by thermal ablation.
[0046] In another embodiment, the present disclosure provides for a
method for retrieving a pig device that has been ablated using the
methods disclosed herein. Such a method 500, illustrated by FIG. 5,
may comprise locating the pig device within a pipeline using radio
signals detected from a radio receiver located within the pig
device in step 510. In step 520, at least one ignition source may
be ignited, wherein each ignition source is operably coupled to an
incendiary charge. Once ignited, the incendiary charge releases at
least one exothermic material into one or more thermal dispersion
channels. The interior of each thermal dispersion channel may be
melted in step 530 to disperse the exothermic material through the
inner core and thereby destroy the pig device. The pig may be
retrieved in step 540 at the detected location within the pipe.
EXAMPLES
[0047] The following example details experiments designed and
implemented using the pig device and ablation methods of the
present disclosure. FIGS. 6-20 illustrate an exemplary pig design
used in the experimental set up described herein. FIG. 6
illustrates the base of a pig device with a polyurethane foam inner
core. An incendiary charge with two igniters is illustrated in FIG.
7 and FIG. 8 illustrates this incendiary charge loaded into the
base of the pig device. The radio receiver is shown loaded into the
pig device in FIG. 9.
[0048] Testing results show that the materials and devices
consistent with commercial pipe pigging may be effectively ablated
or destroyed in place within the pipe to consistently allow
materials to be flushed from the pipe past or through significant
obstructions using water as a motive force. Due to the combustion
process of the methods of the present disclosure, water as the
motive force is the only method which may be used in this method of
thermal ablation as the water acts a heat sink for the process and
effectively protects the pipe from damage. Testing shows that class
200 PVC pipe exhibited zero thickness loss, zero pipe wall
distortion and a maximum external temperature of 8.7.degree. F.
over the inside of the pipe when surrounded by air. Testing shows
pipe discoloration from products of combustion but no surface
erosion due to the combustion process. The interior of a pipe after
ablation of a pig device using the methods described herein in FIG.
20.
[0049] FIGS. 15-20 illustrate the experimental design set forth
herein. In FIG. 15, the pig device is inserted into a pipe. The
dimensions of a rock used as an obstruction in this experimental
design are set forth in FIGS. 16A, 16B, and 16C. FIG. 16A shows the
width of the rock obstruction as being approximately four inches.
FIG. 16B shows the length of the rock obstruction as being
approximately seven inches and FIG. 16C shows the height of the
rock obstruction as being approximately 2.5 inches.
[0050] To deflagrate the pig via chemical means in an environment
devoid of oxygen gas, such as a pipe, requires utilizing oxidizing
agents to provide the necessary oxygen atoms to the system. In this
specific case the exothermal reagents must continue to burn even
when submerged in water. To accomplish this, a modified form of
Ellern's formulation number 36.sup.1 was used which utilizes
magnesium and aluminum for fuels with barium sulfate and barium
nitrate serving as the oxidizing agents.
[0051] The formulation of Ellern was originally intended to be used
in underwater flares and therefore holds potential for the present
invention. It is, by mass, 16% magnesium, 12% aluminum, 32% barium
nitrate, and 32% barium sulfate with an unspecified amount of
manganese oxide mixed in with linseed oil to form a binder. With
these mass ratios the barium sulfate and barium nitrate are
together limiting reactants. Experiments have shown that use of
Ellern's formulation will result in difficulty starting the main
reaction. It was assumed that the manganese oxide was part of a
thermitic reaction to help achieve the activation energy needed to
initiate the main reaction. The manganese oxide was removed from
the reaction and replaced with stoichiometric amounts of aluminum
and iron (III) oxide added prior to combining with the binder. The
Al/Fe.sub.2O.sub.3 reaction is also known to have a relatively low
ignition point and be highly exothermic, thus helping to both start
the reaction and sustain the high burn temperature needed
underwater. The following amounts of each material were used in the
present experimental design:
TABLE-US-00001 Modified Formulation: (% composition by mass)
Magnesium 12.1% Aluminum 15.2% Barium Nitrate 24.2% Barium Sulfate
30.3% Iron (III) Oxide 18.2%
[0052] To prepare the exothermal mixture atomized aluminum and 325
mesh granular magnesium were combined with powdered forms of the
oxidizers and homogenized. The homogenized granular powder was then
compounded with pure, unboiled, linseed oil (p=0.93 g/ml) using 6
ml of linseed oil per hundred grams of powder to form the material
for the charge. The pig device and methods of the present
disclosure are not limited to these concentrations. It is
contemplated that the following workable ranges of materials may be
used (% composition by mass): barium nitrate from about 22.5% to
about 27.5%; barium sulfate from about 25.3% to about 33.5%; iron
(III) sulfate from about 14.8% to about 19.4%; aluminum fro about
12.8% to about 15.8%; and magnesium from about 10.4% to about
13.5%.
[0053] Approximately 210 grams of the exothermal material was
packed into a hollow cardboard tube (1.75'' diameter, 4.24'' long).
It is noted that other materials may be used to house the
exothermal material including but not limited to glass and plastic.
To help insure that the material ignited, a small disk
(approximately 1/8'' thick and approximately 1'' in diameter) of
secondary ignition material (described herein) was placed on top of
the exothermal material and a commercially available pyrotechnics
igniter was then placed on top of the secondary ignition material.
Cloth medical tape was used to securely fasten the igniter to the
ignition material and to seal the end of the tube. It is
contemplated that other types of tape or other mechanisms may be
used so long as the mechanism securely fastens the igniter and the
ignition material and to seal the end of the tube. The cloth tape
was then used to secure the igniter wire to the long axis of the
tube for stress relief and to ensure that the igniter was not
pulled away from the ignition material. This process was repeated
on the other end of the charge; each charge has two ignition points
(See FIG. 7).
[0054] In early tests the commercially available igniters were not
always capable of starting the reaction for the primary charge. A
secondary ignition charge made of sucrose and potassium nitrate was
added between the commercially available igniter and the main
charge. The secondary charge was made by mixing 65% potassium
nitrate with 35% sucrose; this is a mixture commonly found in model
rocketry. The mixture was thoroughly homogenized and then carefully
heated (to approximately 160.degree. C.) until the sugar oxidized,
turned light brown, and underwent a phase change to form a paste.
The paste was then spread on wax paper at approximate 1/8''
thickness for cooling. Once re-crystallized, the material was
broken into appropriate sized pieces and shaped for use as the
secondary ignition material.
[0055] There are five heat producing oxidation-reduction reactions
used in this device. Reaction enthalpies at 298K were determined by
using standard enthalpies of formation.sup.2 and the state law
equation. In addition the heat liberated per gram of reactant was
also computed.
10 Al ( s ) + 3 Ba ( NO 3 ) 2 ( s ) .fwdarw. 3 BaO ( s ) + 3 N 2 (
g ) + 5 Al 2 O 3 ( s ) .DELTA. H rxn o = - 1684.47 kcal ( 1601 cal
/ g ) ( Rxn . 1 ) 16 Al ( s ) + 8 BaSO 4 ( s ) .fwdarw. 8 BaO ( s )
+ 3 S 8 ( s ) + 8 Al 2 O 3 ( s ) .DELTA. H rxn o = - 1458.32 kcal (
634 cal / g ) ( Rxn . 2 ) 5 Mg ( s ) + Ba ( NO 3 ) 2 ( s ) .fwdarw.
BaO ( s ) + N 2 ( g ) + 5 MgO ( s ) .DELTA. H rxn o = - 615.54 kcal
( 1608 cal / g ) ( Rxn . 3 ) 24 Mg ( s ) + 8 BaSO 4 ( s ) .fwdarw.
8 BaO ( s ) + S 8 ( s ) + 24 MgO ( s ) .DELTA. H rxn o = - 1717.76
kcal ( 701 cal / g ) ( Rxn . 4 ) 2 Al ( s ) + Fe 2 O 3 ( s )
.fwdarw. Al 2 O 3 ( s ) + 2 Fe ( s ) .DELTA. H rxn o = - 202.59
kcal ( 948 cal / g ) ( Rxn . 5 ) ##EQU00001##
[0056] These values are in rough agreement with values found in the
literature which listed 1400 cal/g for reaction 1 and 900 cal/g for
reaction 2..sup.3 Since the entire mixture is homogenized before
adding the linseed oil binder it is assumed that the oxidizers are
equally available to their pertinent reactions. As such one may
further assume that half of each of the Ba(NO.sub.3).sub.2 and
BaSO.sub.4 oxidizers goes to each of the fuels. In this formulation
the oxidizers are the limiting reagents and can therefore be used
to stoichiometrically compute the amount of fuel needed and the
amount of energy produced by each reaction as seen in Table 1.
TABLE-US-00002 TABLE 1 Assuming starting masses of 32 g
Ba(NO.sub.3).sub.2, 40 g BaSO.sub.4, and 24 g of Fe.sub.2O.sub.3.
Oxidizer Stoichiometric Energy Reaction Mass Fuel Mass from Rxn 1
16 g Ba(NO.sub.3).sub.2 5.51 g Al 34400 cal 2 20 g BaSO.sub.4 4.62
g Al 15600 cal 3 16 g Ba(NO.sub.3).sub.2 7.44 g Mg 37700 cal 4 20 g
BaSO.sub.4 6.24 g Mg 18400 cal 5 24 g Fe.sub.2O.sub.3 8.11 g Al
30400 cal Total 127.9 g (132 g if including excess fuel) 136500
cal
[0057] Using these totals the energy generated per gram of starting
material is 1040 cal/g (or 4.13 btu/g). The PIG is made of a
polyurethane core material. Polyurethane foams have approximate
heats of combustion of 2400 cal/g (9.52 btu/g).sup.4. To completely
destroy a pig device would therefore require using approximately
2.3 g of exothermic reactants for each gram of polyurethane to be
deflagrated.
[0058] A low density polyurethane pig device enclosing 210 grams of
exothermal reactants described above was ignited while submerged in
20 gallons of water. FIGS. 17, 18, and 19 illustrate the pig
undergoing the reactions described herein. Theoretically, the
exothermal reaction should liberate at most 867 btu of energy and
increase the temperature of the water by 5.18.degree. F. The
temperature of the water was measured via a thermal imager prior to
and immediately after the reaction completed as illustrated in
FIGS. 12-14. A temperature change of approximately 5.degree. F. was
recorded. As such, and within the experimental error of the
measuring devices, the thermochemistry described above is
consistent with the observed experimental results.
[0059] There are numerous exothermal reagents and combinations of
exothermal reagents that could be used to accomplish the pig
deflagration. This application lays claim to the idea of using an
exothermal agent to destroy the pig. In the chemical reactions
described above the following oxidations take place:
Mg.sup.0.fwdarw.Mg.sup.II and Al.sup.0.fwdarw.Al.sup.III. The
reductions are N.sup.V.fwdarw.N.sup.0, S.sup.VI.fwdarw.S.sup.0, and
Fe.sup.III.fwdarw.Fe.sup.0. Because of their location in the
activity series with respect to magnesium and aluminum, several
active metals (lithium, potassium, strontium, calcium, sodium)
could replace barium as the cation in the oxidizing agents.
Similarly, numerous polyatomic ions could potentially be used
instead of nitrate and sulfate. The choices of barium nitrate,
barium sulfate, and iron (iii) oxide for the prototype device
described herein were primarily based on several factors including:
(i) the similarity to Ellern's original formulation; (ii) their
known characteristics within the pyrotechnics industry; (iii) being
readily available from numerous manufacturers; and (iv) the high
burning point and insolubility of barium sulfate in water.
[0060] The present disclosure may be embodied in other specific
forms without departing from the spirit or essential attributes of
the disclosure. Accordingly, reference should be made to the
appended claims, rather than the foregoing specification, as
indicating the scope of the disclosufre. Although the foregoing
description is directed to the embodiments of the disclosure, it is
noted that other variations and modification will be apparent to
those skilled in the art, and may be made without departing from
the spirit or scope of the disclosure.
REFERENCES CITED
[0061] 1. Ellern, Herbert. Military and Civilian Pyrotechnics. (New
York: Chemical Publishing Company, 1968).
[0062] 2. CRC Handbook of Chemistry and Physics, 62nd ed. Robert C.
Weast and Melvin J. Astle, eds. (Boca Raton: CRC Press, 1982). pg.
D-52.
[0063] 3. Engineering Design Handbook, Military Pyrotechnics
Series. Part 1: Theory and Application. (Washington: U.S. Army
Materiel Command, 1967) AMCP 706-185.
[0064] 4. Krasney, John; Parker, William; Babrauskas, Vytenis. Fire
Behavior of Upholstered Furniture and Mattresses. (Norwich: Noyes
Publications, 2001).; Sundstrom, B., Grauers, K., and Purser, D.
Hazard Analysis in Room, Ch. 3, Fire Safety of Upholstered
Furniture--The Full Report of the European Commission Research
Program CBUF. B. Sundstrom, ed. (London: Interscience
Communications Ltd., 1995)
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