CA2271442C - Method and apparatus for thawing ground - Google Patents
Method and apparatus for thawing ground Download PDFInfo
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- CA2271442C CA2271442C CA 2271442 CA2271442A CA2271442C CA 2271442 C CA2271442 C CA 2271442C CA 2271442 CA2271442 CA 2271442 CA 2271442 A CA2271442 A CA 2271442A CA 2271442 C CA2271442 C CA 2271442C
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/11—Improving or preserving soil or rock, e.g. preserving permafrost soil by thermal, electrical or electro-chemical means
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- Engineering & Computer Science (AREA)
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- Structural Engineering (AREA)
- Agronomy & Crop Science (AREA)
- Environmental & Geological Engineering (AREA)
- Soil Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
A method and apparatus for thawing an area of frozen ground, especially to allow building of houses in the winter, includes drilling a series of generally vertical bores, spaced at 4 to 5 feet, into the frozen ground, and inserting a heating probe into each bore. The probes each comprise an outer tubular casing and an inner pipe extending within the casing, the pipe having an outlet near the lower end of the casing. The casing has a length of at least 4.5 feet, and an outside diameter of at least 2.5 inches, preferably at least 3.0 inches. The inner pipe is connected to a source of hot liquid and the casing is connected to an outlet for cool liquid, and the liquid is pumped to each inner pipe so that it flows through the casing of each heating probe, thereby thawing the ground surrounding the bores.
Description
Title: "Method and apparatus for thawing ground"
Backcround of the Invention.
l.Field of the Invention The present invention relates to method and apparatus for 5_ thawing ground, especially in preparation for construction of buildings such as houses.
Backcround of the Invention.
l.Field of the Invention The present invention relates to method and apparatus for 5_ thawing ground, especially in preparation for construction of buildings such as houses.
2.Prior Art If construction is to be carried out in the winter in cold climates, it is usually desirable to thaw the ground before digging operations begin. This avoids problems with heavy ripping equipment needed to dig into frozen soil, and also means that a contractor need not worry that there is frost under the footings.
Hitherto, ground thawing prior to construction has usually been done by apparatus which is laid upon the frozen ground and which heats it from the top. Such apparatus is shown, for example, in the following patents:
U.S.Pat.No.3,868,825, which issued Mar.4, 1975 to Boyce;
U.S.Pat.No.4,349,010, which issued Sept.l4, 1982 to Bentham;
U.S.Pat.No.5,033,452, which issued Ju1.23, 1991, to Carriere;
U.S.Pat.No.5,441,038, which issued Aug.l5, 1995 to Ohmann;
and U.S.Pat.No.5,820,301, which issued Oct.l3, 1998 to Bruckelmyer.
I have found that such apparatus, which heats the ground from the surface, is inefficient and cannot produce sufficient depth of thawing for construction, over the kind to area needed for a house, say 1,200 sq.ft., in reasonable time. Firstly, with such apparatus, at low temperatures such as -30° or -40°
5_ F, much heat supplied to such probes is lost to the air.
Secondly, since heat rises, there is little natural tendency of the heat to penetrate into the ground. This problem is made worse by the drying of the upper layers as they are heated, since the dry air acts to insulate the lower layers from the heat source. I have found that such surface heaters, in cold weather conditions, can only thaw the ground to a depth of 2 to 2.5 feet in one week. The time (of around 2 to 3 weeks) and energy required to thaw to a depth of 5 to 6 feet, as is needed in house construction, is unacceptable.
Some of the designs shown in the patents have other problems. Thus, the Bentham system needs sand or other material as a cover; in really cold weather there is little such material which is available and not frozen solid. This patent also uses gas burners, and such burners need attention or they can become hazardous. With this Bentham arrangement, if one of the burners went out the raw gas would tend to settle, and other burners could ignite the gas . The LP gas container is exposed, and for safety reasons such an arrangement should not be left unattended. Similar comments apply to the Carriere and Ohmann patents which also use gas.
The Bruckelmyer patent has the problem that the moisture, when thawed, will create wet and muddy conditions which make it hard for equipment to move around.
Apparatus has been suggested which involves placing heating tubes vertically in the ground. Thus, U.S.Pat.No.
, CA 02271442 1999-OS-19 3,293,863 to Cox et al. describes apparatus for thawing ground in the vicinity of a sub-surface utility installation, including a tubular heater which is inserted into a vertical bore. The heater is supplied with L.P. gas which is burnt in a 5_ burner near to the bottom of the heater. Exhaust gas leaves the probe via vents at the top of the heater. The heater probe is designed to have its own gas tank, and the arrangement is not suitable for thawing a whole large area, as needed for construction of houses . Again, a probe using gas in this way is 1Q likely to need constant supervision in order not to be hazardous.
U.S.Pats.Nos.5,181,655 and 5,449,113 of Bruckelmyer show water heated probes primarily intended for thawing a frozen sewer or water line. The ' 655 patent suggests that these probes 15 can also be used to thaw construction materials, for example being inserted into holes in bricks. The holes in bricks are usually less than 1.5 inches in diameter, meaning that Bruckelmyer's probes must be quite small, well under 1.5 in outer diameter. The length is not given, but considering the 20 proportions shown in the drawings it seems that the length would be 18 inches or less. The upper ends of the probes have standard pipe fitting type elbows which have diameters similar to those of the probes, and which, given the small diameter of the probes, necessarily extend out way beyond the probe 25 surfaces. Such projecting elbows would easily be damaged if a group of the probes were to be stacked on top of each other.
These patents suggest using an anti-freeze solution which is likely to become lost if the probes are disconnected from the hoses when moving the apparatus.
A system for use in mining is known from Can. Pat.
No.208,350, which issued to Evans on Feb.B, 1921, and which uses vertical pipes feeding water into the ground. If used for construction work, the large amount of water put into the ground would result in very soft and muddy ground conditions.
Such a system also needs a constant supply of water.
Summary of the Invention The present invention provides a system for thawing ground to make it suitable for construction, and which may be used when ambient temperatures are well below freezing, and which is safe with little supervision. The probes are long enough to thaw ground to the kind of depth needed for basements, say to 5 or 6 feet . While the system leaves moisture in the ground, it does not add to it so as to cause the ground to become overly soft . The probes have means to prevent loss of anti-freeze when hoses are detached.
In accordance with one aspect of the invention, a method for thawing an area of frozen ground comprises:
drilling a series of generally vertical bores at a generally even spacing of between about 3 and about 6 feet;
inserting into each bore a heating probe comprising an outer tubular casing and an inner delivery pipe extending within the casing and having an outlet communicating with the lower end of the casing, the casing having an outer diameter of at least 2.5 inches and a length of at least 4.5 feet, and preferably at least 5 feet, connecting the inner pipe to a source of hot liquid and connecting the casing to an outlet for cool liquid; and pumping hot liquid from the source to each inner pipe so that it flows through the pipe and tubular casing of each heating probe and exits through the outlet and returns to the source, thereby thawing the ground surrounding the bores.
Preferably, several of the heating probes are connected in series, with the outlet of one being connected to the inlet of the next. A series of the heating probes may include three or 5_ more such probes forming a first row. A second row of several of said heating probes may also be connected in series, a first heating probe of the first row and a first heating probe of the second row both being directly connected to the source of hot liquid, so that the rows themselves are connected in parallel.
The bores are usually drilled on a grid pattern and spaced between 4 and 5 feet apart. The tubular casings are preferably at least 3.0 inches in outer diameter.
In accordance with another aspect of the invention, apparatus for thawing ground includes a series of heating ~5 probes, wherein each heating probe comprises:
an outer tubular casing having a diameter of at least 2.5 inches, preferably 3 inches, and a length of at least 4.5 feet and having a closed lower end, and an inner pipe extending within the casing and having an open lower end communicating with the outer tubular casing near its lower end.
The tubular casing has an upper end closure provided with first and second apertures, apart from which the casing is closed. The first aperture accommodates and is sealed around an upper end portion of the inner pipe, and the second aperture is in sealed communication with an outlet pipe element. An inlet pipe connector is provided for inlet of hot liquid at the upper end of the inner pipe, and an outlet pipe connector is provided at the outer end of the outlet pipe element.
Hitherto, ground thawing prior to construction has usually been done by apparatus which is laid upon the frozen ground and which heats it from the top. Such apparatus is shown, for example, in the following patents:
U.S.Pat.No.3,868,825, which issued Mar.4, 1975 to Boyce;
U.S.Pat.No.4,349,010, which issued Sept.l4, 1982 to Bentham;
U.S.Pat.No.5,033,452, which issued Ju1.23, 1991, to Carriere;
U.S.Pat.No.5,441,038, which issued Aug.l5, 1995 to Ohmann;
and U.S.Pat.No.5,820,301, which issued Oct.l3, 1998 to Bruckelmyer.
I have found that such apparatus, which heats the ground from the surface, is inefficient and cannot produce sufficient depth of thawing for construction, over the kind to area needed for a house, say 1,200 sq.ft., in reasonable time. Firstly, with such apparatus, at low temperatures such as -30° or -40°
5_ F, much heat supplied to such probes is lost to the air.
Secondly, since heat rises, there is little natural tendency of the heat to penetrate into the ground. This problem is made worse by the drying of the upper layers as they are heated, since the dry air acts to insulate the lower layers from the heat source. I have found that such surface heaters, in cold weather conditions, can only thaw the ground to a depth of 2 to 2.5 feet in one week. The time (of around 2 to 3 weeks) and energy required to thaw to a depth of 5 to 6 feet, as is needed in house construction, is unacceptable.
Some of the designs shown in the patents have other problems. Thus, the Bentham system needs sand or other material as a cover; in really cold weather there is little such material which is available and not frozen solid. This patent also uses gas burners, and such burners need attention or they can become hazardous. With this Bentham arrangement, if one of the burners went out the raw gas would tend to settle, and other burners could ignite the gas . The LP gas container is exposed, and for safety reasons such an arrangement should not be left unattended. Similar comments apply to the Carriere and Ohmann patents which also use gas.
The Bruckelmyer patent has the problem that the moisture, when thawed, will create wet and muddy conditions which make it hard for equipment to move around.
Apparatus has been suggested which involves placing heating tubes vertically in the ground. Thus, U.S.Pat.No.
, CA 02271442 1999-OS-19 3,293,863 to Cox et al. describes apparatus for thawing ground in the vicinity of a sub-surface utility installation, including a tubular heater which is inserted into a vertical bore. The heater is supplied with L.P. gas which is burnt in a 5_ burner near to the bottom of the heater. Exhaust gas leaves the probe via vents at the top of the heater. The heater probe is designed to have its own gas tank, and the arrangement is not suitable for thawing a whole large area, as needed for construction of houses . Again, a probe using gas in this way is 1Q likely to need constant supervision in order not to be hazardous.
U.S.Pats.Nos.5,181,655 and 5,449,113 of Bruckelmyer show water heated probes primarily intended for thawing a frozen sewer or water line. The ' 655 patent suggests that these probes 15 can also be used to thaw construction materials, for example being inserted into holes in bricks. The holes in bricks are usually less than 1.5 inches in diameter, meaning that Bruckelmyer's probes must be quite small, well under 1.5 in outer diameter. The length is not given, but considering the 20 proportions shown in the drawings it seems that the length would be 18 inches or less. The upper ends of the probes have standard pipe fitting type elbows which have diameters similar to those of the probes, and which, given the small diameter of the probes, necessarily extend out way beyond the probe 25 surfaces. Such projecting elbows would easily be damaged if a group of the probes were to be stacked on top of each other.
These patents suggest using an anti-freeze solution which is likely to become lost if the probes are disconnected from the hoses when moving the apparatus.
A system for use in mining is known from Can. Pat.
No.208,350, which issued to Evans on Feb.B, 1921, and which uses vertical pipes feeding water into the ground. If used for construction work, the large amount of water put into the ground would result in very soft and muddy ground conditions.
Such a system also needs a constant supply of water.
Summary of the Invention The present invention provides a system for thawing ground to make it suitable for construction, and which may be used when ambient temperatures are well below freezing, and which is safe with little supervision. The probes are long enough to thaw ground to the kind of depth needed for basements, say to 5 or 6 feet . While the system leaves moisture in the ground, it does not add to it so as to cause the ground to become overly soft . The probes have means to prevent loss of anti-freeze when hoses are detached.
In accordance with one aspect of the invention, a method for thawing an area of frozen ground comprises:
drilling a series of generally vertical bores at a generally even spacing of between about 3 and about 6 feet;
inserting into each bore a heating probe comprising an outer tubular casing and an inner delivery pipe extending within the casing and having an outlet communicating with the lower end of the casing, the casing having an outer diameter of at least 2.5 inches and a length of at least 4.5 feet, and preferably at least 5 feet, connecting the inner pipe to a source of hot liquid and connecting the casing to an outlet for cool liquid; and pumping hot liquid from the source to each inner pipe so that it flows through the pipe and tubular casing of each heating probe and exits through the outlet and returns to the source, thereby thawing the ground surrounding the bores.
Preferably, several of the heating probes are connected in series, with the outlet of one being connected to the inlet of the next. A series of the heating probes may include three or 5_ more such probes forming a first row. A second row of several of said heating probes may also be connected in series, a first heating probe of the first row and a first heating probe of the second row both being directly connected to the source of hot liquid, so that the rows themselves are connected in parallel.
The bores are usually drilled on a grid pattern and spaced between 4 and 5 feet apart. The tubular casings are preferably at least 3.0 inches in outer diameter.
In accordance with another aspect of the invention, apparatus for thawing ground includes a series of heating ~5 probes, wherein each heating probe comprises:
an outer tubular casing having a diameter of at least 2.5 inches, preferably 3 inches, and a length of at least 4.5 feet and having a closed lower end, and an inner pipe extending within the casing and having an open lower end communicating with the outer tubular casing near its lower end.
The tubular casing has an upper end closure provided with first and second apertures, apart from which the casing is closed. The first aperture accommodates and is sealed around an upper end portion of the inner pipe, and the second aperture is in sealed communication with an outlet pipe element. An inlet pipe connector is provided for inlet of hot liquid at the upper end of the inner pipe, and an outlet pipe connector is provided at the outer end of the outlet pipe element.
Preferably, the inlet pipe connector is joined to the inner pipe by a first elbow, and the outlet pipe element includes a second elbow, both the elbows and pipe connectors attached thereto being arranged so as to be entirely within a 5_ cylindrical surface corresponding to an extension of the tubular casing. This allows a large number of the probes, such as the number required for thawing a house site, to be stacked up without any of the elbows or pipe fittings attached to the elbows extending out beyond the cylindrical surfaces of the respective probes and thus protects such elbows and fittings from damage.
Preferably also, the connectors include valves which close automatically when hoses are disconnected therefrom.
Brief description of the drav~inqs.
A preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which;
Fig.l is an elevation of a heating probe;
Fig.2 is a view of the heating probe on lines 2-2 of Fig. l;
Fig.3 is a plan view of the same heating probe, on lines 3-3 of Fig. l;
Fig.4 is a perspective view of the apparatus in use thawing an area of ground, and 2_~ Fig.5 is a vertical section through ground being thawed by one of the heating probes.
Detailed Description.
Figs.l to 3 show one of the heating probes 10; typically 100 such probes will be used to thaw an area of ground, say of 1,200 sq.ft., suitable for a house.
Each probe has an outer tubular, cylindrical casing 12, closed at its bottom end by a welded plate 13. The casing is formed from standard 3 inch (internal) diameter pipe, having an outer diameter of 3.5 inch. The length of the probe will be typically be between 5 and 8 feet long.
The top end of the casing 12 is closed by a top plate 14 which has two apertures providing the only inlets or outlets into the casing. A first aperture accommodates and is sealed around an upper end portion of a delivery pipe 16, and a second aperture is sealed around the lower end of an outlet pipe element in the form of elbow 18 which provides the sole outlet from the space within the casing. The upper end of pipe 16 is also provided with an elbow, indicated at 19, through which hot liquid can be fed to the probe via the pipe. The pipe extends within the casing, spaced away from the casing walls, and a lower, open, end of the delivery pipe, which is located near to the bottom end of the casing, is held in a radially central position by means of a spacer tab 20 welded to the side of the pipe near its lower end.
The upper plate 14 extends slightly beyond the cylindrical surface of the casing so as to limit its descent into a close fitting bore drilled for it, as will be described. A lifting loop 22 is provided above the plate 14 to allow extraction of the probe.
Each elbow 18 and 19 is provided with an internally threaded pipe connector 24; these are of the "ball valve connector" type which include a ball valve which closes the connector when it is not attached to a hose. These connectors, and the elbows themselves, are arranged to be entirely confined within a cylindrical surface corresponding to an extension of the casing outer surface, so that the probes can be rolled around and stacked without these parts coming into contact with and being damaged by the ground or by other probes.
The diameter of the casing is many times that of the delivery pipe 16, which is typically a 1/2 inch internal diameter pipe, so that when heated liquid is supplied to the pipe and leaves its lower end the hot liquid passes up the casing relatively slowly. Preferably the internal area of the casing surrounding the pipe is more than 20 or 30 times the internal area of the pipe, and in the preferred embodiment is about 40 times the internal area of the pipe, so that the residence time in the casing is relatively long.
Figs.4 and 5 show the probes in use. The ground to be thawed has been prepared by having vertical bore holes H
drilled into it on a square grid pattern, the bore holes having a diameter of about 3.5 to 4 inches, and having a 4 to 5 foot spacing. The probes are placed within the holes, and connected by hoses to a mobile boiler 30 in a trailer which includes a pump and which supplies hot liquid to the probes . The boiler is arranged to be locked when not being under supervision, to avoid any tampering or accidents. As shown, the arrangement includes a series of rows of heating probes indicated A, B, C, D. Normally, more (say 100 or so) heating probes will be used to thaw an area of say 1, 200 square feet suitable for a typical house.
The heating probes 10 are all connected to the boiler 30 by insulated hoses comprising outlet conduits 32 and return conduits 34, attached to the connectors 18 and 19. The conduits connect the heating probes of each row in series, the outlet of one being connected to the inlet of the next, so that the hot liquid flows through each probe of the row in turn. The first probe of each row is directly connected to the outlet from the boiler via conduits 32a, 32b, etc., and the last probe of each row is connected to a return conduit 34a, 34b, etc . leading back to the boiler, so that the rows themselves are connected in parallel.
In operation, the area being thawed by the probes is covered with an insulated tarp, a portion of which is shown at 36. Heated liquid containing anti-freeze is pumped from the boiler through the conduits 32, 34 and into successive delivery pipes 16, passing to the bottoms of the probe casings and moving up the probes while radiating heat into the surrounding ground. Each probe will thaw an area around it, reaching out to a radius of about 2 to 2.5 feet; the pattern of thawing is shown in Fig.5, where FS is frozen soil and TS is thawed soil.
The method allows moisture to remain in the ground, but does not add to it . Vehicles can travel on the thawed ground without encountering mud or soft areas . The ground is easy to excavate .
The system is also safer than those which use gas burners to produce heated gas. The heating apparatus, i.e. the boiler, remains in a trailer which can be locked. The hot probes are submerged, and the hot liquid passes through insulated hoses.
The system does not require superheated liquid, or high pressure, so there is little chance of injury even if leaks occur. To move the apparatus, the probes are simply pulled up, the tarps are wrapped up, and hoses coiled for transport.
The valued connectors on the probes prevent anti-freeze solution being lost when the hoses are detached therefrom.
Preferably also, the connectors include valves which close automatically when hoses are disconnected therefrom.
Brief description of the drav~inqs.
A preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which;
Fig.l is an elevation of a heating probe;
Fig.2 is a view of the heating probe on lines 2-2 of Fig. l;
Fig.3 is a plan view of the same heating probe, on lines 3-3 of Fig. l;
Fig.4 is a perspective view of the apparatus in use thawing an area of ground, and 2_~ Fig.5 is a vertical section through ground being thawed by one of the heating probes.
Detailed Description.
Figs.l to 3 show one of the heating probes 10; typically 100 such probes will be used to thaw an area of ground, say of 1,200 sq.ft., suitable for a house.
Each probe has an outer tubular, cylindrical casing 12, closed at its bottom end by a welded plate 13. The casing is formed from standard 3 inch (internal) diameter pipe, having an outer diameter of 3.5 inch. The length of the probe will be typically be between 5 and 8 feet long.
The top end of the casing 12 is closed by a top plate 14 which has two apertures providing the only inlets or outlets into the casing. A first aperture accommodates and is sealed around an upper end portion of a delivery pipe 16, and a second aperture is sealed around the lower end of an outlet pipe element in the form of elbow 18 which provides the sole outlet from the space within the casing. The upper end of pipe 16 is also provided with an elbow, indicated at 19, through which hot liquid can be fed to the probe via the pipe. The pipe extends within the casing, spaced away from the casing walls, and a lower, open, end of the delivery pipe, which is located near to the bottom end of the casing, is held in a radially central position by means of a spacer tab 20 welded to the side of the pipe near its lower end.
The upper plate 14 extends slightly beyond the cylindrical surface of the casing so as to limit its descent into a close fitting bore drilled for it, as will be described. A lifting loop 22 is provided above the plate 14 to allow extraction of the probe.
Each elbow 18 and 19 is provided with an internally threaded pipe connector 24; these are of the "ball valve connector" type which include a ball valve which closes the connector when it is not attached to a hose. These connectors, and the elbows themselves, are arranged to be entirely confined within a cylindrical surface corresponding to an extension of the casing outer surface, so that the probes can be rolled around and stacked without these parts coming into contact with and being damaged by the ground or by other probes.
The diameter of the casing is many times that of the delivery pipe 16, which is typically a 1/2 inch internal diameter pipe, so that when heated liquid is supplied to the pipe and leaves its lower end the hot liquid passes up the casing relatively slowly. Preferably the internal area of the casing surrounding the pipe is more than 20 or 30 times the internal area of the pipe, and in the preferred embodiment is about 40 times the internal area of the pipe, so that the residence time in the casing is relatively long.
Figs.4 and 5 show the probes in use. The ground to be thawed has been prepared by having vertical bore holes H
drilled into it on a square grid pattern, the bore holes having a diameter of about 3.5 to 4 inches, and having a 4 to 5 foot spacing. The probes are placed within the holes, and connected by hoses to a mobile boiler 30 in a trailer which includes a pump and which supplies hot liquid to the probes . The boiler is arranged to be locked when not being under supervision, to avoid any tampering or accidents. As shown, the arrangement includes a series of rows of heating probes indicated A, B, C, D. Normally, more (say 100 or so) heating probes will be used to thaw an area of say 1, 200 square feet suitable for a typical house.
The heating probes 10 are all connected to the boiler 30 by insulated hoses comprising outlet conduits 32 and return conduits 34, attached to the connectors 18 and 19. The conduits connect the heating probes of each row in series, the outlet of one being connected to the inlet of the next, so that the hot liquid flows through each probe of the row in turn. The first probe of each row is directly connected to the outlet from the boiler via conduits 32a, 32b, etc., and the last probe of each row is connected to a return conduit 34a, 34b, etc . leading back to the boiler, so that the rows themselves are connected in parallel.
In operation, the area being thawed by the probes is covered with an insulated tarp, a portion of which is shown at 36. Heated liquid containing anti-freeze is pumped from the boiler through the conduits 32, 34 and into successive delivery pipes 16, passing to the bottoms of the probe casings and moving up the probes while radiating heat into the surrounding ground. Each probe will thaw an area around it, reaching out to a radius of about 2 to 2.5 feet; the pattern of thawing is shown in Fig.5, where FS is frozen soil and TS is thawed soil.
The method allows moisture to remain in the ground, but does not add to it . Vehicles can travel on the thawed ground without encountering mud or soft areas . The ground is easy to excavate .
The system is also safer than those which use gas burners to produce heated gas. The heating apparatus, i.e. the boiler, remains in a trailer which can be locked. The hot probes are submerged, and the hot liquid passes through insulated hoses.
The system does not require superheated liquid, or high pressure, so there is little chance of injury even if leaks occur. To move the apparatus, the probes are simply pulled up, the tarps are wrapped up, and hoses coiled for transport.
The valued connectors on the probes prevent anti-freeze solution being lost when the hoses are detached therefrom.
Claims (5)
1. Apparatus for thawing ground, including a series of heating probes, wherein each heating probe comprises:
an outer tubular casing having a diameter of at least 2.5 inches and a length of at least 4.5 feet and having an upper end and a closed lower end, an inner pipe extending within said tubular casing and having an open lower end communicating with the tubular casing near its said closed lower end, and such that said tubular casing provides an annular space between the casing and the inner pipe for return flow of liquid having a cross-sectional area which is at least 20 times that of the interior of the inner pipe;
said tubular casing having an upper end closure provided with first and second apertures, said apertures providing the only inlets or outlets into the casing, said first aperture accommodating and being sealed around an upper end portion of said inner pipe, and said second aperture being in sealed communication with an outlet pipe element;
an inlet pipe connector for inlet hot liquid at the upper end of the inner pipe, and an outlet pipe connector at the outlet of said outlet pipe element, the arrangement being such that all the liquid supplied to the inlet pipe connector passes down the pipe and up the tubular casing before leaving the outlet pipe connector.
an outer tubular casing having a diameter of at least 2.5 inches and a length of at least 4.5 feet and having an upper end and a closed lower end, an inner pipe extending within said tubular casing and having an open lower end communicating with the tubular casing near its said closed lower end, and such that said tubular casing provides an annular space between the casing and the inner pipe for return flow of liquid having a cross-sectional area which is at least 20 times that of the interior of the inner pipe;
said tubular casing having an upper end closure provided with first and second apertures, said apertures providing the only inlets or outlets into the casing, said first aperture accommodating and being sealed around an upper end portion of said inner pipe, and said second aperture being in sealed communication with an outlet pipe element;
an inlet pipe connector for inlet hot liquid at the upper end of the inner pipe, and an outlet pipe connector at the outlet of said outlet pipe element, the arrangement being such that all the liquid supplied to the inlet pipe connector passes down the pipe and up the tubular casing before leaving the outlet pipe connector.
2. Apparatus according to claim 1, wherein the outer diameter of said tubular casing is at least 3.0 inches.
3. Apparatus according to claim 1, wherein said inlet pipe connector is joined to the inner pipe by a first elbow, and wherein said outlet pipe element includes a second elbow, both said elbows and pipe connectors attached thereto being arranged so as to be entirely within a cylindrical volume defined by an extension of the tubular casing.
4. Apparatus according to claim 1, wherein said inlet pipe connector and said outlet pipe connector are suitable for connection of hoses thereto, and said connectors include valves which close automatically when said hoses are disconnected therefrom.
5. Apparatus according to claim 1, wherein the upper end of the tubular casing is provided with a lifting loop.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2271442 CA2271442C (en) | 1999-05-19 | 1999-05-19 | Method and apparatus for thawing ground |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2271442 CA2271442C (en) | 1999-05-19 | 1999-05-19 | Method and apparatus for thawing ground |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2271442C true CA2271442C (en) | 2000-09-05 |
Family
ID=29588975
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2271442 Expired - Fee Related CA2271442C (en) | 1999-05-19 | 1999-05-19 | Method and apparatus for thawing ground |
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| Country | Link |
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| CA (1) | CA2271442C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107687321A (en) * | 2017-07-29 | 2018-02-13 | 中国地质调查局油气资源调查中心 | One kind frost drilled via equipment and its application method |
| US10443312B2 (en) | 2015-12-28 | 2019-10-15 | Michael J Davis | System and method for heating the ground |
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1999
- 1999-05-19 CA CA 2271442 patent/CA2271442C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10443312B2 (en) | 2015-12-28 | 2019-10-15 | Michael J Davis | System and method for heating the ground |
| US10669782B2 (en) | 2015-12-28 | 2020-06-02 | Michael J. Davis | System and method for heating the ground |
| CN107687321A (en) * | 2017-07-29 | 2018-02-13 | 中国地质调查局油气资源调查中心 | One kind frost drilled via equipment and its application method |
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| MKLA | Lapsed |