CA2639090A1 - Geothermal grout having enhanced thermal conductivity - Google Patents
Geothermal grout having enhanced thermal conductivity Download PDFInfo
- Publication number
- CA2639090A1 CA2639090A1 CA 2639090 CA2639090A CA2639090A1 CA 2639090 A1 CA2639090 A1 CA 2639090A1 CA 2639090 CA2639090 CA 2639090 CA 2639090 A CA2639090 A CA 2639090A CA 2639090 A1 CA2639090 A1 CA 2639090A1
- Authority
- CA
- Canada
- Prior art keywords
- grout
- aluminum oxide
- geothermal
- thermal conductivity
- bentonite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/001—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing unburned clay
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/70—Grouts, e.g. injection mixtures for cables for prestressed concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Dispersion Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Abstract
A geothermal grout contains aluminum oxide in the amount of about 65 percent by weight but can contain up to 90 percent by weight of aluminum oxide. The remainder of the grout can be wholly composed of bentonite or can contain bentonite and any one or more of the following ingredients: aluminum oxide, copper sulfate, iron oxide and iron
Description
It is well known that the temperature of fluids can be raised by means of geothermal energy from the heat of the earth. The temperature of earth rises with increasing depth from the surface and the temperature of liquids likewise rises as the depth of their surroundings under-ground increases. When the liquid is extracted from the earth, its thermal energy can be har-nessed in ways that depend upon the depth at which the liquid is situated. For example, water at a depth of about 2.5 km, is generally in the form of steam. In areas of volcanic activity and thermal springs, steam occurs at considerably lesser depths. The steam when extracted from the earth can be injected directly onto the blades of a turbine in order to drive a generator.
It is also known that the temperature of fluids can be lowered by geothermal means. For example, hot water from an air conditioner or refrigerator can be circulated into the earth in order to cool the water to the temperature of the earth.
In its simplest form, geothermal energy is produced by causing a liquid to flow downward from the surface of the earth through a bore hole to a predetermined depth.
The heated liquid is then returned to the earth's surface through another bore hole and, where its temperature is raised in the earth, its heat or thermal energy is extracted and harnessed for the production of energy.
Alternatively where the temperature of the liquid is lowered in the earth, the liquid can flow to an air conditioner, refrigerator or other cooling device where its low temperature can be harnessed for cooling purposes.
Geothermal heating and cooling is carried out in various known apparatus. Heat pumps and compressors, for example are used both for heating and cooling. Glycol or a mixture of glycol and water is frequently used as the heating and cooling medium.
Typically the fluid flows through pipes in the ground where it picks up heat from the surrounding earth or gives it up to the earth. The pipes are located in vertical wells or horizontal drill holes or ditches.
The pipe must have good contact with the ground to provide an efficient transfer of heat to or from the fluid which flows in it. Grout is used to ensure that there is such contact. Grout also acts to protect the pipe from movement of the ground and from corrosive liquids in the ground. It also acts as a sealant to prevent contamination of the liquid within the pipe and contamination of ground water by the liquid in the pipe.
The grout is poured in the space between the outer wall of the pipe and the wall of the hole in which the pipe is located. Typically, dirt, clay, sand, cement, graphite, bentonite and even water are used as grout but other substances are also used for this purpose.
Grout is also used in other applications. Electricity generating plants encase wires in con-crete in order to insulate the surrounding earth from the heat of the wires.
Cable companies also use grout to fill the space around their wires and pipes.
The thermal conductivity of the grout has a significant impact on the required depth of the pipe and hence the cost of its installation. The more efficient the heat transfer between the liquid in the pipe and the earth surrounding the pipe, the shorter the length of pipe required to provide a given transfer of heat. A grout that does not effectively conduct heat can act as an insulator and
It is also known that the temperature of fluids can be lowered by geothermal means. For example, hot water from an air conditioner or refrigerator can be circulated into the earth in order to cool the water to the temperature of the earth.
In its simplest form, geothermal energy is produced by causing a liquid to flow downward from the surface of the earth through a bore hole to a predetermined depth.
The heated liquid is then returned to the earth's surface through another bore hole and, where its temperature is raised in the earth, its heat or thermal energy is extracted and harnessed for the production of energy.
Alternatively where the temperature of the liquid is lowered in the earth, the liquid can flow to an air conditioner, refrigerator or other cooling device where its low temperature can be harnessed for cooling purposes.
Geothermal heating and cooling is carried out in various known apparatus. Heat pumps and compressors, for example are used both for heating and cooling. Glycol or a mixture of glycol and water is frequently used as the heating and cooling medium.
Typically the fluid flows through pipes in the ground where it picks up heat from the surrounding earth or gives it up to the earth. The pipes are located in vertical wells or horizontal drill holes or ditches.
The pipe must have good contact with the ground to provide an efficient transfer of heat to or from the fluid which flows in it. Grout is used to ensure that there is such contact. Grout also acts to protect the pipe from movement of the ground and from corrosive liquids in the ground. It also acts as a sealant to prevent contamination of the liquid within the pipe and contamination of ground water by the liquid in the pipe.
The grout is poured in the space between the outer wall of the pipe and the wall of the hole in which the pipe is located. Typically, dirt, clay, sand, cement, graphite, bentonite and even water are used as grout but other substances are also used for this purpose.
Grout is also used in other applications. Electricity generating plants encase wires in con-crete in order to insulate the surrounding earth from the heat of the wires.
Cable companies also use grout to fill the space around their wires and pipes.
The thermal conductivity of the grout has a significant impact on the required depth of the pipe and hence the cost of its installation. The more efficient the heat transfer between the liquid in the pipe and the earth surrounding the pipe, the shorter the length of pipe required to provide a given transfer of heat. A grout that does not effectively conduct heat can act as an insulator and
2 inhibit the transfer of heat to the liquid.
It is known to use clay such as bentonite as a grout in geothermal applications. Bentonite contains up to about 10 percent by weight aluminum oxide. Compounds of iron such as iron oxide, and oxides of copper are also found in bentonite. Bentonite has relatively good dimen-sional stability and bonding characteristics which are important qualities of grout used for geo-thermal purposes. Bentonite however generally has relatively low thermal conductivity compared to other substances which are commonly used as grout. .
I have found that if additional aluminum oxide is combined with bentonite to increase the overall quantity of aluminum oxide to as high as 90 percent by weight but preferably not more than 65 % by weight, the thermal conductivity of the grout increases significantly. The resulting grout is easy to mix and pump using conventional equipment and meets the generally recognized standards required for grout such as satisfactory permeability, minimum shrinkage, satisfactory bonding, durability, ease of handling and so on.
The thermal conductivity of other substances commonly used as grout such as concrete is also enhanced by the addition of aluminum oxide. If sufficient aluminum oxide is combined with such substances to produce a product having about 25 to 30 percent by weight aluminum oxide, there is a significant improvement in the thermal conductivity in the product.
The grout of the invention can include additional components including a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide or combinations
It is known to use clay such as bentonite as a grout in geothermal applications. Bentonite contains up to about 10 percent by weight aluminum oxide. Compounds of iron such as iron oxide, and oxides of copper are also found in bentonite. Bentonite has relatively good dimen-sional stability and bonding characteristics which are important qualities of grout used for geo-thermal purposes. Bentonite however generally has relatively low thermal conductivity compared to other substances which are commonly used as grout. .
I have found that if additional aluminum oxide is combined with bentonite to increase the overall quantity of aluminum oxide to as high as 90 percent by weight but preferably not more than 65 % by weight, the thermal conductivity of the grout increases significantly. The resulting grout is easy to mix and pump using conventional equipment and meets the generally recognized standards required for grout such as satisfactory permeability, minimum shrinkage, satisfactory bonding, durability, ease of handling and so on.
The thermal conductivity of other substances commonly used as grout such as concrete is also enhanced by the addition of aluminum oxide. If sufficient aluminum oxide is combined with such substances to produce a product having about 25 to 30 percent by weight aluminum oxide, there is a significant improvement in the thermal conductivity in the product.
The grout of the invention can include additional components including a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide or combinations
3 thereof.
It will be understood, of course, that modification can be made in the composition of the grout of the invention without departing from the scope of the invention as defined in the appended claims.
It will be understood, of course, that modification can be made in the composition of the grout of the invention without departing from the scope of the invention as defined in the appended claims.
4
Claims (6)
1. A geothermal grout containing aluminum oxide in the amount of not more than percent by weight.
2. The geothermal grout of claim 1 in which the content of aluminum oxide does not exceed about 65 percent by weight.
3. The geothermal grout of claims 1 or 2 which contains essentially only bentonite and aluminum oxide.
4. A geothermal grout comprising: bentonite and a substance selected from the group comprising: aluminum oxide, copper sulfate, iron oxide and iron.
5. The geothermal grout of claim 4 wherein said substance comprises not more than about 90 % by weight of said geothermal grout.
6. The geothermal grout of claim 4 wherein said substance comprises not more than about 65 % by weight of said geothermal grout.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2639090 CA2639090A1 (en) | 2008-08-15 | 2008-08-15 | Geothermal grout having enhanced thermal conductivity |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2639090 CA2639090A1 (en) | 2008-08-15 | 2008-08-15 | Geothermal grout having enhanced thermal conductivity |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2639090A1 true CA2639090A1 (en) | 2010-02-15 |
Family
ID=41697620
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2639090 Abandoned CA2639090A1 (en) | 2008-08-15 | 2008-08-15 | Geothermal grout having enhanced thermal conductivity |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2639090A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2995396A1 (en) * | 2012-09-10 | 2014-03-14 | Brgm | Thermal storage device, useful in aquifer, comprises heat exchanger placed in well that is clogged by composition including aluminum oxide, where the aluminum oxide is tubular calcined white corundum aluminum oxide in powder form |
-
2008
- 2008-08-15 CA CA 2639090 patent/CA2639090A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2995396A1 (en) * | 2012-09-10 | 2014-03-14 | Brgm | Thermal storage device, useful in aquifer, comprises heat exchanger placed in well that is clogged by composition including aluminum oxide, where the aluminum oxide is tubular calcined white corundum aluminum oxide in powder form |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |