EP0114644A2 - Electric steam generator - Google Patents
Electric steam generator Download PDFInfo
- Publication number
- EP0114644A2 EP0114644A2 EP84100435A EP84100435A EP0114644A2 EP 0114644 A2 EP0114644 A2 EP 0114644A2 EP 84100435 A EP84100435 A EP 84100435A EP 84100435 A EP84100435 A EP 84100435A EP 0114644 A2 EP0114644 A2 EP 0114644A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- heating elements
- liquid
- electric steam
- steam generator
- electric
- 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- Withdrawn
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/28—Methods of steam generation characterised by form of heating method in boilers heated electrically
- F22B1/284—Methods of steam generation characterised by form of heating method in boilers heated electrically with water in reservoirs
Definitions
- the present invention relates to an electric steam boiler. Two types of electric boilers are currently known.
- the first type for small powers in which the heating elements consist of immersion heaters comprising one or more electrical resistors of solid circular section inside a metal sheath and insulated therefrom by an insulator such as magnesia, alumina or boron nitride. These resistances are multiple, they are curved in a U shape and fed at their ends.
- the second type reserved for more powerful boilers, includes plunging electrodes, the water in the boiler forming an electrical resistance between these electrodes.
- the object of the present invention is an electric boiler which is particularly well suited for a power range between 1 and 15 MW.
- the invention therefore relates to an electric boiler for producing steam comprising heating elements immersed in the liquid, said heating elements being constituted by tubes or plates, not insulated, electrically conductive supplied electrically at each of their ends, the surfaces said conductive elements being in direct contact with the liquid characterized in that said heating elements have asperities so that these surfaces are not isothermal.
- the heat fluxes obtained can be very high and greater than 500 W / cm 2 of active surface, whereas in the best of cases, with conventional immersion heaters, a maximum of 70 W / cm 2 is reached.
- the heating element shown in the figures consists of a tube 1 which is not electrically insulated, the internal and external surfaces of which are asperities as 2 and 3 and are in direct contact with the liquid which is not shown; the electric current flowing through the heating element practically does not pass into the boiling liquid.
- these asperities are formed by longitudinal grooves whose section is triangular.
- asperities can have a different section and be cut into several sections in their axial length. They are intended to ensure that the temperature is not uniform on the external as well as internal surface of the tube in order to stabilize, on the curve of the heat transfer flow as a function of the temperature difference between the surface and the liquid, the heat flow at the critical point and thus avoid the phenomenon of calefaction.
- the hottest points do not exceed the critical point because they are in a way retained by the least hot points. It therefore stabilizes around this critical point for which very large heat fluxes are obtained, without reaching the zone for which the heating elements are destroyed.
- the tube 1 is for example made of graphite, stainless steel, cupronickel or the like. It must be sufficiently electrically resistant in order to avoid too long lengths and the thermal conductivity must also not be too large in order to have a sufficient temperature gradient between the bottom 4 of the asperities and their ends 5. It is therefore necessary to avoid materials such as copper and aluminum.
- the tube 1 is supplied at the ends by conductors 6 and 7.-In the example described, the heating element shown is a tube but it is also possible to use a plate also provided with asperities on its two surfaces and not insulated and directly in contact with the liquid.
- the volume occupied by the heating elements made up of conductive tubes with high thermal flux is much lower than for conventional solutions.
- the boilers are less bulky and lower in cost.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Resistance Heating (AREA)
- Instantaneous Water Boilers, Portable Hot-Water Supply Apparatuses, And Control Of Portable Hot-Water Supply Apparatuses (AREA)
- Control Of Resistance Heating (AREA)
- Fire-Extinguishing Compositions (AREA)
- Insulated Conductors (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Description
La présente invention concerne une chaudière électrique à vapeur. On connaît actuellement deux types de chaudières électriques.The present invention relates to an electric steam boiler. Two types of electric boilers are currently known.
Le premier type, pour les petites puissances dans lequel les éléments chauffants sont constitués par des thermoplongeurs comprenant une ou plusieurs résistances électriques de section circulaire pleine à l'intérieur d'une gaine métallique et isolée de celle-ci par un isolant tel que de la magnésie, de l'alumine ou du nitrure de bore. Ces résistances sont multiples, elles sont courbées en forme de U et alimentées à leurs extrémités. Le second type, réservé aux chaudières plus puissantes comporte des électrodes plongeantes, l'eau de la chaudière formant résistance électrique entre ces électrodes.The first type, for small powers in which the heating elements consist of immersion heaters comprising one or more electrical resistors of solid circular section inside a metal sheath and insulated therefrom by an insulator such as magnesia, alumina or boron nitride. These resistances are multiple, they are curved in a U shape and fed at their ends. The second type, reserved for more powerful boilers, includes plunging electrodes, the water in the boiler forming an electrical resistance between these electrodes.
Dans la gamme de puissance moyenne, de l'ordre de 2 MW à 15 MW, ni l'un ni l'autre de ces types ne sont satisfaisant. En effet, les thermoplongeurs, même dans les cas les plus performants conduisent à un coût de chaudière élevé en raison du grand nombre d'éléments et les chaudières à électrodes conduisent également dans cette gamme de puissance à un prix de revient prohibitif.In the medium power range, of the order of 2 MW to 15 MW, neither of these types is satisfactory. Indeed, the immersion heaters, even in the most efficient cases lead to a high boiler cost due to the large number of elements and the electrode boilers also lead in this power range at a prohibitive cost price.
La présente invention a pour but une chaudière électrique particulièrement bien adaptée pour une gamme de puissance comprise entre 1 et 15 MW.The object of the present invention is an electric boiler which is particularly well suited for a power range between 1 and 15 MW.
L'invention a donc pour objet une chaudière électrique de production de vapeur comportant des éléments chauffants plongés dans le liquide, lesdits éléments chauffants étant constitués par des tubes ou des plaques, non isolés, électriquement conducteurs alimentés électriquement à chacune de leurs extrémités, les surfaces desdits éléments conducteurs étant en contact direct avec le liquide caractérisé en ce que lesdits éléments chauffants comportent des aspérités de manière à ce que ces surfaces ne soient pas isothermes.The invention therefore relates to an electric boiler for producing steam comprising heating elements immersed in the liquid, said heating elements being constituted by tubes or plates, not insulated, electrically conductive supplied electrically at each of their ends, the surfaces said conductive elements being in direct contact with the liquid characterized in that said heating elements have asperities so that these surfaces are not isothermal.
Grâce à cette structure les flux thermiques obtenus peuvent être très élevés et supérieurs À 500 W/cm2 de surface active alors que dans le meilleur des cas, avec des thermoplongeurs classiques on arrive à un maximum de 70 W/cm2.Thanks to this structure, the heat fluxes obtained can be very high and greater than 500 W / cm 2 of active surface, whereas in the best of cases, with conventional immersion heaters, a maximum of 70 W / cm 2 is reached.
On va maintenant décrire un exemple de réalisation de l'invention en se référant au dessin ci-joint dans lequel :
- La figure 1 montre en coupe axiale un élément chauffant selon l'invention pour une chaudière électrique.
- La figure 2 est une coupe selon II-II de la figure 1.
- Figure 1 shows in axial section a heating element according to the invention for an electric boiler.
- Figure 2 is a section on II-II of Figure 1.
L'élément chauffant représenté sur les figures est constitué par un tube 1 non isolé électriquement dont les surfaces interne et externe sont pourvues d'aspérités telles que 2 et 3 et sont en contact direct avec le liquide non représenté ; le courant électrique parcourant l'élément chauffant ne passe pratiquement pas dans le liquide en ébullition.The heating element shown in the figures consists of a
Dans les figures représentées, ces aspérités sont constituée par des rainures longitudinales dont la section est triangulaire.In the figures shown, these asperities are formed by longitudinal grooves whose section is triangular.
Ces aspérités peuvent avoir une section différente et être découpées en plusieurs tronçons dans leur longueur axiale. Elles ont pour but de faire en sorte que la température ne soit pas uniforme sur la surface aussi bien externe qu'interne du tube afin de stabiliser, sur la courbe du flux de transfert thermique en fonction de la différence de température entre la surface et le liquide, le flux thermique au point critique et d'éviter ainsi le phénomène de caléfaction.These asperities can have a different section and be cut into several sections in their axial length. They are intended to ensure that the temperature is not uniform on the external as well as internal surface of the tube in order to stabilize, on the curve of the heat transfer flow as a function of the temperature difference between the surface and the liquid, the heat flow at the critical point and thus avoid the phenomenon of calefaction.
En effet, grâce à cette disposition les points les plus chauds ne dépassent pas le point critique car ils sont en quelque sorte retenus par les points les moins chauds. On se stabilise donc à l'entour de ce point critique pour lequel on obtient de très grands flux thermiques, sans atteindre la zone pour laquelle on détruit les éléments chauffants.In fact, thanks to this arrangement, the hottest points do not exceed the critical point because they are in a way retained by the least hot points. It therefore stabilizes around this critical point for which very large heat fluxes are obtained, without reaching the zone for which the heating elements are destroyed.
Le tube 1 est par exemple en graphite, acier inoxydable, cupronickel ou autre. Il doit être suffisamment résistant électriquement afin d'éviter de trop grandes longueurs et la conductivité thermique ne doit pas être non plus trop grande afin d'avoir un gradient de température suffisant entre le fond 4 des aspérités et leur extrémités 5. Il faut donc éviter les matériaux tels que le cuivre et l'aluminium.The
Le tube 1 est alimenté aux extrémités par des conducteurs 6 et 7.-Dans l'exemple décrit, l'élément chauffant représenté est un tube mais on peut également utiliser une plaque également munie d'aspérités sur ses deux surfaces et non isolée et directement en contact avec le liquide.The
Grâce à la solution selon l'invention, le volume occupé par les éléments chauffants constitués de tubes conducteurs à haut flux thermique est beaucoup plus faible que pour les solutions classiques. Les chaudières sont moins encombrantes et de coûts moins élevés.Thanks to the solution according to the invention, the volume occupied by the heating elements made up of conductive tubes with high thermal flux is much lower than for conventional solutions. The boilers are less bulky and lower in cost.
Claims (1)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8300761 | 1983-01-19 | ||
FR8300761A FR2539487B1 (en) | 1983-01-19 | 1983-01-19 | ELECTRIC STEAM PRODUCTION BOILER |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0114644A2 true EP0114644A2 (en) | 1984-08-01 |
EP0114644A3 EP0114644A3 (en) | 1984-08-22 |
Family
ID=9285067
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84100435A Withdrawn EP0114644A3 (en) | 1983-01-19 | 1984-01-17 | Electric steam generator |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0114644A3 (en) |
BR (1) | BR8400211A (en) |
FR (1) | FR2539487B1 (en) |
NO (1) | NO840157L (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR476151A (en) * | 1914-04-07 | 1915-07-15 | Jean Bally | Improvements to electric boilers |
CH82214A (en) * | 1918-12-16 | 1920-02-02 | Eduard Meystre | Electrical heating device in which resistance bodies connected to the heating circuit give off their heat to a liquid |
US1420692A (en) * | 1920-10-12 | 1922-06-27 | Hyman E Cohen | Electric water heater and steam generator |
CH101973A (en) * | 1922-07-07 | 1923-11-01 | Grant Percy | Electric radiator and process for its manufacture. |
US2200265A (en) * | 1938-05-26 | 1940-05-14 | Westinghouse Electric & Mfg Co | Electric steam generator |
-
1983
- 1983-01-19 FR FR8300761A patent/FR2539487B1/en not_active Expired
-
1984
- 1984-01-17 EP EP84100435A patent/EP0114644A3/en not_active Withdrawn
- 1984-01-17 NO NO840157A patent/NO840157L/en unknown
- 1984-01-18 BR BR8400211A patent/BR8400211A/en not_active IP Right Cessation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR476151A (en) * | 1914-04-07 | 1915-07-15 | Jean Bally | Improvements to electric boilers |
CH82214A (en) * | 1918-12-16 | 1920-02-02 | Eduard Meystre | Electrical heating device in which resistance bodies connected to the heating circuit give off their heat to a liquid |
US1420692A (en) * | 1920-10-12 | 1922-06-27 | Hyman E Cohen | Electric water heater and steam generator |
CH101973A (en) * | 1922-07-07 | 1923-11-01 | Grant Percy | Electric radiator and process for its manufacture. |
US2200265A (en) * | 1938-05-26 | 1940-05-14 | Westinghouse Electric & Mfg Co | Electric steam generator |
Also Published As
Publication number | Publication date |
---|---|
EP0114644A3 (en) | 1984-08-22 |
BR8400211A (en) | 1984-08-21 |
FR2539487A1 (en) | 1984-07-20 |
FR2539487B1 (en) | 1987-09-11 |
NO840157L (en) | 1984-07-20 |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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PUAL | Search report despatched |
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AK | Designated contracting states |
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AK | Designated contracting states |
Designated state(s): CH DE FR LI SE |
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17P | Request for examination filed |
Effective date: 19850222 |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: ALSTHOM |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 19870304 |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: VERGER, BERNARD |