EP0130671A2 - Selbstregelndes Heizelement mit mehreren Temperaturen - Google Patents

Selbstregelndes Heizelement mit mehreren Temperaturen Download PDF

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Publication number
EP0130671A2
EP0130671A2 EP84302907A EP84302907A EP0130671A2 EP 0130671 A2 EP0130671 A2 EP 0130671A2 EP 84302907 A EP84302907 A EP 84302907A EP 84302907 A EP84302907 A EP 84302907A EP 0130671 A2 EP0130671 A2 EP 0130671A2
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EP
European Patent Office
Prior art keywords
layer
layers
ferromagnetic
curie temperature
ferromagnetic layer
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.)
Withdrawn
Application number
EP84302907A
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English (en)
French (fr)
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EP0130671A3 (de
Inventor
Howard L. Rose
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Metcal Inc
Original Assignee
Metcal Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Metcal Inc filed Critical Metcal Inc
Publication of EP0130671A2 publication Critical patent/EP0130671A2/de
Publication of EP0130671A3 publication Critical patent/EP0130671A3/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/105—Induction heating apparatus, other than furnaces, for specific applications using a susceptor
    • H05B6/108—Induction heating apparatus, other than furnaces, for specific applications using a susceptor for heating a fluid
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2206/00—Aspects relating to heating by electric, magnetic, or electromagnetic fields covered by group H05B6/00
    • H05B2206/02—Induction heating
    • H05B2206/023—Induction heating using the curie point of the material in which heating current is being generated to control the heating temperature

Definitions

  • the present invention relates to autoregulating electric heaters and more particularly, to an electromagnetic autoregulating electric heater that autoregulates at two or more selectable temperatures.
  • an autoregulating electric heater having a laminated structure; one lamina of which has high magnetic permeability and high resistance and another lamina of which is non-magnetic and has a low resistance (such as copper-) in electrical contact, and therefore, thermal contact with the first lamina.
  • This structure is adapted to be connected across a constant current, a.c., source such that the layers are in a sense in parallel across the source.
  • P power
  • K 1 2 which is a constant
  • R the effective resistance of the permeable material at high current concentrations.
  • the dissipation of power heats the layer until it approaches its Curie temperature.
  • the permeability of the lamina decreases towards the level of the second layer, copper for instance, at about its Curie temperature.
  • the device thus thermally autoregulates over a narrow temperature range about the Curie temperature.
  • the current source employed in the aforesaid patent is typically a high frequency source, for instance, 8 to 20 MHz to insure that the current is confined to the thin, high resistivity, magnetic layer until the Curie temperature of the magnetic material is attained.
  • the maximum regulation is achieved when the thickness of the magnetic layer is of the order of'one skin depth at the frequency of operation. Under these circumstances, the maximum change in effective resistance of the structure is achieved at or about the Curie temperature.
  • the thickness of the high mu material were materially less than one skin depth, the percentage of current flowing in the high resistivity material at a temperature less than the Curie temperature would be less so.that the change of resistance at the Curie temperature would again not be as dramatic.
  • the region of 1.0 to perhaps 1.8 skin depths of high mu material is preferred.
  • Difficulty may arise in such devices when the Curie temperature is achieved due to spread of the current and/or magnetic flux into adjacent regions outside of the device, particularly if the device is located close to sensitive electrical components.
  • the magnetic field in a simple, single layer, i.e., monolithic structure falls off as e- x so that at three skin depths, the field is 4.9% of maximum, at five skin depths, it is 0.67%, and at ten skin depths, the field is .005% of maximum.
  • thicknesses of three skin depths are satisfactory although ten or more may be required with some highly sensitive devices in the vicinity of large heating currents.
  • the devices of the patent and application are operative for their intended purposes when connected to a suitable supply, but a drawback is the cost of the high frequency power supply.
  • the frequency of the source is preferably maintained quite high, for instance, in the megahertz region, to be able to employ copper or other non-magnetic material having reasonable thicknesses.
  • a relatively low frequency constant current source may be employed as a result of fabricating the normally non-magnetic, low resistivity layer from a high permeability, high Curie temperature material.
  • the device comprises a high permeability, high resistivity first layer adjacent the current return path and a high permeability, preferably low resistivity second layer remote from the return path; the second layer having a higher Curie temperature than the first-mentioned layer.
  • high magnetic permeability refers to materials having permeabilities greater than paramagnetic materials, i.e., ferromagnetic materials, although permeabilities of 100 or more are preferred for most applications.
  • the theory of operation underlying the invention of the aforesaid application filed on September 30 1982 is that by using a high permeability, high Curie temperature material as the low resistivity layer, the skin depth of the current in this second layer is such as to confine the current to a quite thin layer even at low frequencies thereby essentially insulating the outer surfaces electrically and magnetically but not thermally with a low resistivity layer of manageable thickness.
  • the second layer is preferably formed of a low resistivity material, but this is not essential.
  • An example of a device employing two high mu laminae utilizes a layer of Alloy 42 having a resistivity of about 70-80 micro-ohms-cm, a permeability about 200, and a Curie temperature of approximately 300° centigrade.
  • a second layer is formed of carbon steel having a resistivity of about 10 micro-ohms-cm, a permeability of 1000, and a Curie temperature of about 760° centigrade.
  • the skin depths, using a 60 Hz supply are .1" for Alloy 42 and .025" for carbon steel.
  • An example of a practical 60 Hz heater based on the present invention may employ a coaxial heater consisting of a .25 inch diameter cylindrical or tubular copper conductor (the "return” conductor), a thin layer (perhaps .002 in thickness) of insulation, followed by the temperature sensitive magnetic alloy having a permeability of 400 and a thickness of 0.1 inch, and finally an outer jacket of steel having a permeability of 1000 and a thickness of 0.1 inch.
  • the overall heater diameter would be a .65 inch. If the heater is used in a situation requiring 5 watts per foot of heater length for, for instance, protection of a liquid against freezing, the total length of the heater is 1000 feet, the resistance of the heater will be 1.96 ohms.
  • the current will be 50 amperes, and the voltage at the generator end will be 140 volts at temperatures somewhat below the Curie temperature of the temperature sensitive magnetic alloy on the inside of the outer pipe. If there were substantial changes in the electrical resistance due to variations of the thermal load, the required voltage must vary in order to maintain constant current. Either of these latter supplies provide current at costs considerably less than a constant current supply at 8-20 MHz.
  • the power regulation ratios (AR) in such a device are not as high as with the device of the patent with a resistivity difference of about 10:1, but the AR difference may be reduced by using materials of higher and lower resistivities for the low Curie temperature and high Curie temperature materials, respectively. Also, a high mu, relatively low resistivity material such as iron or low carbon steel may be employed to further increase the power regulation ratio.
  • the objects of the invention are achieved by providing a region of high conductivity at the interface of the two members having high permeability as set forth in the Krumme application, S.N. 430,317, filed on September 30, 1982.
  • the material in the interface region may be copper, for instance, or other highly conductive material.
  • the material may appear as a separate layer, a sandwich of magnetic, non-magnetic and magnetic material or may be bonded to the high and/or low Curie temperature, ferromagnetic layers at the interface to provide a low resistivity, interface region.
  • Typical thicknesses of the sandwich construction at 1 KHz are 0.03" for both the low and high Curie temperature ferromagnetic materials, respectively, and .010 inch for the copper layer.
  • a low frequency is meant a source in the range of 50 Hz to 10,000 Hz although 50 Hz-8000 Hz is fully adequate.
  • conductive material may refer to a highly conductive non-magnetic material such as copper or a ferromagnetic material of relatively high conductivity and a Curie temperature well above the Curie temperatures of the ferromagnetic,surface coatings. In the latter case, a thin layer of copper or the like may be interposed between the surface layers and the ferromagnetic substrate to increase conductivity above the Curie temperature of the ferromagnetic layers.
  • two current return paths are employed each adjacent to and insulated from a different one of the laminates of ferromagnetic material; the return path and ferromagnetic material being connected together at one end of the structure only.
  • a constant current source is, by means of appropriate switching arrangements, alternatively connected across one or the other of the pairs of ferromagnetic coating and its return path.
  • Autoregulation occurs in the region of the Curie temperature of the connected ferromagnetic coating.
  • the conductive laminate is of sufficient thickness, 5 to 10 skin depths to prevent interaction of the ferromagnetic layers. Since each of the two surface coatings have different Curie temperatures, the apparatus autoregulates at about the Curie temperature of the surface coating connected in the circuit.
  • constant current does not mean a current that cannot vary, but means a current that obeys the following formula: Specifically, in order to autoregulate, the power delivered to the load when the heater exceeds Curie temperature, must be less than the power delivered to the load below Curie temperature. If the current is held invariable, then the best autoregulating ratio is achieved short of controlling the power supply to reduce current. So long, however, as the current is reduced sufficiently to reduce heating, autoregulation is achieved. Thus, when large autoregulating ratios are not required, constraints on the degree of current control may be relaxed thus reducing the cost of the power supply.
  • a device that autoregulates at more than two temperatures is also disclosed by providing insulating spaces between pairs of autoregulating devices. Specifically, the concentration of current in a conductor due to skin effect is on the surface of the conductor adjacent the current return path. If three layers separated hy two conductive paths are employed in an attempt to provide a device with three (or more) autoregulating temperatures, a conductive path is provided along both surfaces of the ferromagnetic material, and the current will flow at all times predominantly in the conductive medium and autoregulation is defeated. By providing a non-conductive space between certain of the layers, three or more temperatures may be achieved.
  • Another object of the present invention is to provide a multi-temperature autoregulating heater in which the desired temperature may be selected at will.
  • a dual temperature heater having a substrate or lamina- 1 of conductive material coated on its top and bottom surfaces as illustrated in Fig. 1, with layers 3 and 5, respectively, of ferromagnetic materials of different Curie temperatures.
  • Layers 3 and 5 are provided with insulating layers 2 and 4 located between layers 3 and 5 and current return conductors 6 and 8, respectively.
  • a constant current source 7, has its two terminals connected to movable contacts 9 and 10 of a double pole double throw switch 11.
  • the movable contacts 9 and 17 are switchable between stationary contacts 13 and 15, on the one hand, and contacts 19 and 21, on the other.
  • Contacts 13 and 14 are connected respectively to ferromagnetic layer 5 and conductive layer 8.
  • Contacts 19 and 21 are connected to layers 6 and 3, respectively.
  • the layers 1, 6 and 8 are all connected together via a lead 10 at the end of the device remote from the connection of the source 7 to the structure.
  • the contacts 9 and 17 engage, respectively, contacts 19 and 21.
  • the resultant heating quickly raises the temperature of the device to about the Curie temperature of the layer 3.
  • the mu of the layer falls to about one, and the current spreads into the conductive layer 1.
  • the I 2 R losses decrease due to a large decrease in the value of R and the temperature falls below the Curie temperature of the layer 3, the heating rate increases and the cycle repeats to maintain temperature at the desired level.
  • the switch 11 is activated to engage contacts 13 and 15. The cycle described above is repeated with temperature maintained at a temperature determined by the material of layer 5.
  • the material of the layer 1 may be copper or the like in which case maximum autoregulation ratio is achieved. It is preferable, though not essential in many cases, that the layer 1 be 5 to 10 skin depths thick to prevent interaction of the two magnetic layers.
  • the layer 1 may also be a relatively high conductivity ferromagnetic material having a Curie temperature well above those of layers 3 and 5.
  • the autoregulation ratio of such a device is not as high as with copper, but the thickness of the layer 1 may be less due to the shielding effect of the magnetic material of the layer 1.
  • the improvement disclosed in Application S.N. 445,862 may be employed.
  • the layer 1, as well as the layers 3 and 5, is ferromagnetic, and a thin layer of copper or the like is disposed between layer 1 and the layers 3 and 5.
  • thin conductive layers 23 and 25 are located between layer 1 and layers 3 and 5, respectively.
  • Fig. 3 of the accompanying drawings there is illustrated a dual temperature heater patterned after the device of Fig. 5 of the aforesaid Carter et al patent.
  • a single current return conductor 27 of rectangular cross-section is surrounded, in the order stated, by a heat conductive, electrically insulating layer 29, for instance, of beryllium oxide, a ferromagnetic layer 31, a layer 33 that is conductive relative to layer 31, a second thermally conductive, electrically insulating layer 35, a second ferromagnetic layer 37, and a relatively conductive layer 39.
  • Ferromagnetic layers 31 and 37 have different Curie temperatures and layers 33 and 39 may be non-magnetic conductors or ferromagnetic materials as described relative to Fig. 2.
  • the device is in a shielded configuration in that by choosing an appropriate thickness of the layer 39, generation of magnetic fields external to the apparatus may be eliminated.
  • the device is not limited in the location of its applicability and may be wrapped around pipes to prevent freezing, used in diesel fuel heaters or any other location where dual heat may be desirable, such as surgical scalpels.
  • the entire device may be coated with beryllium oxide so that it is electrically but not thermally insulated from its environment.
  • the device is completed by connecting the ferromagnetic layers 31 and 37 together and to the conductor 27 via leads 32, 38 and 28.
  • a source 41 has one end connected via lead 42 connected to return conductor 27 and the other end connected to the center contact 44 of a single pole double throw switch 43.
  • a contact 48 is connected to layer 31 and a second contact 50 is connected to layer 37.
  • the autoregulating temperature of the device may be selected from two different temperatures.
  • ferromagnetic layers 31 and 37 equal to 5 to 10 skin depths thick, when the layers are above their Curie temperature, the layers 33 and 39 may be eliminated since interaction between layers 31 and 37 would be obviated and the layer 37 would be thick enough to prevent radiation even when the layers become non-magnetic. Such a device would not have very good autoregulation but would be sufficient in certain areas of use.
  • FIG. 4 of the accompanying drawings there is illustrated a cylindrical 1 version of the device of Fig. 3.
  • the elements of Fig. 4 corresponding to those of Fig. 3 bear the same reference numerals with primes.
  • the device of Fig. 4 is a thru temperature device having added layers such as layer 45 of insulation, layer 47 of a ferromagnetic material of a third Curie temperature and a final copper (shielding) layer 49.
  • the shielding layers 33 1 , 39 1 , and 49 may be eliminated by making the ferromagnetic layers 5 to 10 skin depths thick.
  • the device is provided with a source 41 and a single pole triple through switch 51 having stationary contacts 52, 54 and 56 connected to layer 3l , 37 and 47, respectively, so that any one of the three layers and its associated Curie temperature may be selected. Of course, any number of layers, within reason, may be added to achieve even more temperatures.
  • the insulating layer 29 of Fig. 3 has been eliminated to provide a gap between return conductor 27 1 and ferromagnetic layer 31 1 .
  • This gap insulates such members from one another and may be employed to heat fluids; air, gas, water, or other liquid, for a variety of purposes. Any one of the insulating layers may be removed to accept fluid and in fact, three different fluids may be heated simultaneously to three different temperatures. Spiders of insulating material may be used to maintain separation between the layers.
  • the liquid may constitute the current return path and replace the copper rod 27 1 .
  • the conductive liquid may replace any one of the copper layers 33 , 39 1 , or others as layers are added.
  • the conductive liquid should be centrally located in the device.
  • the devices may be cylindrical or flat, may be a solid stack using beryllium copper, or the like, separators or a hollow stack or cylinder using air gap separation.
  • the switches employed may be mechanical, electromechanical or electronic and if either of the latter two lend themselves for use with automatic process controllers.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Induction Heating (AREA)
  • Resistance Heating (AREA)
EP84302907A 1983-05-26 1984-04-30 Selbstregelndes Heizelement mit mehreren Temperaturen Withdrawn EP0130671A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US49828283A 1983-05-26 1983-05-26
US498282 1995-10-02

Publications (2)

Publication Number Publication Date
EP0130671A2 true EP0130671A2 (de) 1985-01-09
EP0130671A3 EP0130671A3 (de) 1986-12-17

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JP (1) JPS59226490A (de)
CA (1) CA1224836A (de)

Cited By (43)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0250094A1 (de) * 1986-06-10 1987-12-23 Metcal Inc. Selbstregulierendes Hochleistungsheizelement
EP0252719B1 (de) * 1986-07-07 1992-11-11 Chisso Engineering CO. LTD. Elektrischer Flüssigkeitserhitzer
US5480398A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Endoscopic instrument with disposable auto-regulating heater
US5480397A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Surgical instrument with auto-regulating heater and method of using same
WO1996038019A1 (en) * 1995-05-25 1996-11-28 Electric Power Research Institute Method and apparatus for providing multiple autoregulated temperatures
US5593406A (en) * 1992-05-01 1997-01-14 Hemostatic Surgery Corporation Endoscopic instrument with auto-regulating heater and method of using same
US5611798A (en) * 1995-03-02 1997-03-18 Eggers; Philip E. Resistively heated cutting and coagulating surgical instrument
FR2766048A1 (fr) * 1997-07-11 1999-01-15 Ego Elektro Geratebau Gmbh Systeme d'echauffement
WO2005106193A1 (en) * 2004-04-23 2005-11-10 Shell Internationale Research Maatschappij B.V. Temperature limited heaters used to heat subsurface formations
GB2430219A (en) * 2003-04-24 2007-03-21 Shell Int Research Subsurface heating system
US7831133B2 (en) 2005-04-22 2010-11-09 Shell Oil Company Insulated conductor temperature limited heater for subsurface heating coupled in a three-phase WYE configuration
US7831134B2 (en) 2005-04-22 2010-11-09 Shell Oil Company Grouped exposed metal heaters
US8200072B2 (en) * 2002-10-24 2012-06-12 Shell Oil Company Temperature limited heaters for heating subsurface formations or wellbores
US8292879B2 (en) 2009-04-17 2012-10-23 Domain Surgical, Inc. Method of treatment with adjustable ferromagnetic coated conductor thermal surgical tool
US8617151B2 (en) 2009-04-17 2013-12-31 Domain Surgical, Inc. System and method of controlling power delivery to a surgical instrument
US8833453B2 (en) 2010-04-09 2014-09-16 Shell Oil Company Electrodes for electrical current flow heating of subsurface formations with tapered copper thickness
US8851170B2 (en) 2009-04-10 2014-10-07 Shell Oil Company Heater assisted fluid treatment of a subsurface formation
US8859942B2 (en) 2010-04-09 2014-10-14 Shell Oil Company Insulating blocks and methods for installation in insulated conductor heaters
US8857051B2 (en) 2010-10-08 2014-10-14 Shell Oil Company System and method for coupling lead-in conductor to insulated conductor
US8858544B2 (en) 2011-05-16 2014-10-14 Domain Surgical, Inc. Surgical instrument guide
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US8932279B2 (en) 2011-04-08 2015-01-13 Domain Surgical, Inc. System and method for cooling of a heated surgical instrument and/or surgical site and treating tissue
US8939207B2 (en) 2010-04-09 2015-01-27 Shell Oil Company Insulated conductor heaters with semiconductor layers
US8943686B2 (en) 2010-10-08 2015-02-03 Shell Oil Company Compaction of electrical insulation for joining insulated conductors
US9016370B2 (en) 2011-04-08 2015-04-28 Shell Oil Company Partial solution mining of hydrocarbon containing layers prior to in situ heat treatment
US9048653B2 (en) 2011-04-08 2015-06-02 Shell Oil Company Systems for joining insulated conductors
US9078655B2 (en) 2009-04-17 2015-07-14 Domain Surgical, Inc. Heated balloon catheter
US9080409B2 (en) 2011-10-07 2015-07-14 Shell Oil Company Integral splice for insulated conductors
US9080917B2 (en) 2011-10-07 2015-07-14 Shell Oil Company System and methods for using dielectric properties of an insulated conductor in a subsurface formation to assess properties of the insulated conductor
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US9131977B2 (en) 2009-04-17 2015-09-15 Domain Surgical, Inc. Layered ferromagnetic coated conductor thermal surgical tool
US9181780B2 (en) 2007-04-20 2015-11-10 Shell Oil Company Controlling and assessing pressure conditions during treatment of tar sands formations
US9226341B2 (en) 2011-10-07 2015-12-29 Shell Oil Company Forming insulated conductors using a final reduction step after heat treating
US9265556B2 (en) 2009-04-17 2016-02-23 Domain Surgical, Inc. Thermally adjustable surgical tool, balloon catheters and sculpting of biologic materials
US9309755B2 (en) 2011-10-07 2016-04-12 Shell Oil Company Thermal expansion accommodation for circulated fluid systems used to heat subsurface formations
US9337550B2 (en) 2010-10-08 2016-05-10 Shell Oil Company End termination for three-phase insulated conductors
US9399905B2 (en) 2010-04-09 2016-07-26 Shell Oil Company Leak detection in circulated fluid systems for heating subsurface formations
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Cited By (92)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0250094A1 (de) * 1986-06-10 1987-12-23 Metcal Inc. Selbstregulierendes Hochleistungsheizelement
EP0252719B1 (de) * 1986-07-07 1992-11-11 Chisso Engineering CO. LTD. Elektrischer Flüssigkeitserhitzer
US5593406A (en) * 1992-05-01 1997-01-14 Hemostatic Surgery Corporation Endoscopic instrument with auto-regulating heater and method of using same
US5480398A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Endoscopic instrument with disposable auto-regulating heater
US5480397A (en) * 1992-05-01 1996-01-02 Hemostatic Surgery Corporation Surgical instrument with auto-regulating heater and method of using same
US5611798A (en) * 1995-03-02 1997-03-18 Eggers; Philip E. Resistively heated cutting and coagulating surgical instrument
WO1996038019A1 (en) * 1995-05-25 1996-11-28 Electric Power Research Institute Method and apparatus for providing multiple autoregulated temperatures
FR2766048A1 (fr) * 1997-07-11 1999-01-15 Ego Elektro Geratebau Gmbh Systeme d'echauffement
US8200072B2 (en) * 2002-10-24 2012-06-12 Shell Oil Company Temperature limited heaters for heating subsurface formations or wellbores
US8238730B2 (en) * 2002-10-24 2012-08-07 Shell Oil Company High voltage temperature limited heaters
US8224164B2 (en) * 2002-10-24 2012-07-17 Shell Oil Company Insulated conductor temperature limited heaters
US8224163B2 (en) * 2002-10-24 2012-07-17 Shell Oil Company Variable frequency temperature limited heaters
GB2430219A (en) * 2003-04-24 2007-03-21 Shell Int Research Subsurface heating system
GB2430217A (en) * 2003-04-24 2007-03-21 Shell Int Research Method for heating a subsurface formation
GB2430219B (en) * 2003-04-24 2007-07-25 Shell Int Research Subsurface heating system and method
WO2005106196A1 (en) * 2004-04-23 2005-11-10 Shell Internationale Research Maatschappij B.V. Temperature limited heaters used to heat subsurface formations
EA011007B1 (ru) * 2004-04-23 2008-12-30 Шелл Интернэшнл Рисерч Маатсхаппий Б.В. Ограниченные по температуре нагреватели, применяемые для нагревания подземных пластов
WO2005106193A1 (en) * 2004-04-23 2005-11-10 Shell Internationale Research Maatschappij B.V. Temperature limited heaters used to heat subsurface formations
US8355623B2 (en) 2004-04-23 2013-01-15 Shell Oil Company Temperature limited heaters with high power factors
EA010678B1 (ru) * 2004-04-23 2008-10-30 Шелл Интернэшнл Рисерч Маатсхаппий Б.В. Ограниченные по температуре нагреватели, применяемые для нагревания подземных пластов
AU2005238941B2 (en) * 2004-04-23 2008-11-13 Shell Internationale Research Maatschappij B.V. Temperature limited heaters used to heat subsurface formations
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CA1224836A (en) 1987-07-28
JPS59226490A (ja) 1984-12-19

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