EP0156221A2 - Water heater - Google Patents

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Publication number
EP0156221A2
EP0156221A2 EP85102625A EP85102625A EP0156221A2 EP 0156221 A2 EP0156221 A2 EP 0156221A2 EP 85102625 A EP85102625 A EP 85102625A EP 85102625 A EP85102625 A EP 85102625A EP 0156221 A2 EP0156221 A2 EP 0156221A2
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EP
European Patent Office
Prior art keywords
water
electric heating
water heater
heater according
heating element
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.)
Granted
Application number
EP85102625A
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German (de)
French (fr)
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EP0156221A3 (en
EP0156221B1 (en
Inventor
Erwin Dipl.-Ing. Gross
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C and F Czepek und Fentross GmbH
Original Assignee
C and F Czepek und Fentross GmbH
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
Priority claimed from DE19848407212 external-priority patent/DE8407212U1/en
Priority claimed from DE19848408655 external-priority patent/DE8408655U1/en
Application filed by C and F Czepek und Fentross GmbH filed Critical C and F Czepek und Fentross GmbH
Priority to AT85102625T priority Critical patent/ATE48690T1/en
Publication of EP0156221A2 publication Critical patent/EP0156221A2/en
Publication of EP0156221A3 publication Critical patent/EP0156221A3/en
Application granted granted Critical
Publication of EP0156221B1 publication Critical patent/EP0156221B1/en
Expired 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
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/005—Anodic protection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/18—Water-storage heaters
    • F24H1/20—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes
    • F24H1/201—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes using electric energy supply
    • F24H1/202—Water-storage heaters with immersed heating elements, e.g. electric elements or furnace tubes using electric energy supply with resistances
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H9/00—Details
    • F24H9/0005—Details for water heaters
    • F24H9/001—Guiding means
    • F24H9/0015—Guiding means in water channels
    • F24H9/0021—Sleeves surrounding heating elements or heating pipes, e.g. pipes filled with heat transfer fluid, for guiding heated liquid

Definitions

  • the invention relates on the one hand to a water heater such.
  • a water heater such as B. hot water tank, instantaneous water heater, boiling water device with an electric heating insert and on the other hand on electric radiators in water heaters such as hot water tanks with an internal corrosion protection coating.
  • Water heaters such as B. hot water tank, water heater, household appliances, chemical-technical apparatus and. a., which are heated with electric heating inserts, are at risk from limescale deposits on the heating elements due to overheating, depending on the water hardness.
  • Proposals are known to prevent the deposition of hardness on the electric heating element by utilizing the electrolytic dissociation effect: By applying a direct voltage between the heating element and the container wall - whereby the jacket tube of the heating element is connected as the anode and the container wall as the cathode - the ions of the hardness elements are preferentially turned on the container wall is deposited.
  • the cladding tube of the electric heating insert must consist of an anodically passivatable material, such as, for. B. titanium, tantalum or niobium.
  • the cladding tube must be coated on the outer surface in addition to ensure a sufficient current transfer with a thin layer of noble metal from the platinum series (DE-OS 31 05 922).
  • An object of the present invention is to provide a water heater such as. B. hot water storage tank, instantaneous water heater, boiling water device with an electric heating insert comprising a cladding tube made of an anodically passivatable material with a coating with a noble metal from the platinum series so that a material and thus inexpensive protection of the electric heating insert against limescale takes place.
  • the object is achieved in that the precious metal layer is applied to form coating-free spots in any geometric pattern on the cladding tube of the heating element.
  • the noble metal layer surfaces preferably form a regularly recurring geometric pattern.
  • areas of noble metal ie, e.g. B. platinized and non-platinized surfaces evenly distributed over the entire surface of the heating element.
  • the electro-chemical effect described below can be used for the limescale protection of the surfaces not coated with the precious metal.
  • H. Carbonic acid is formed on the electric heating rod from the hydrogen carbonate ions that are separated here. The latter immediately dissolves a calcium or magnesium carbonate layer that forms on the platinum-free areas. This effect is particularly effective with an area ratio of titanium area to platinum area of 1: to 2: 1, the distance between the platinized areas being approximately 1-2 cm.
  • the areas free of the precious metal layer can be obtained by winding covering tapes in a spiral or ring shape when the platinum layer is applied, as well as by applying synthetic resin or covering masks.
  • an additional cathodic surface in the form of a jacket around the heating element.
  • a sheet metal z. B the surface can be closed or segmented. But it can also consist of a metal wire mesh, metal rods, or a perforated expanded metal grid.
  • the invention relates to an electric heating insert with cathodic corrosion protection, which is installed in an electrically insulated manner in a water reservoir with an internal corrosion protection coating.
  • Hot water storage tanks for example with enamelled inner walls, are cathodically protected by sacrificial anodes or external current anodes to prevent corrosion. If such stores are additionally electrically heated with electric radiators, the following difficulties arise: Including the radiator with its bare metal surface in the cathodically protected container wall results in excessive magnesium consumption in the case of magnesium sacrificial anodes or in the case of external current anodes (inert anodes) ) - At certain wall locations of the storage tank, sufficient negative protection potential has not been achieved due to the shadow effect or protective current extraction by the electric heater.
  • the metal screw-in head of the electric radiator was coated with insulating plastic. This is also problematic since, as is well known, even high-quality plastics do not have long-term durability under hot water conditions.
  • a further object of the present invention is to design an electric heating insert with cathodic corrosion protection, which is installed in an electrically insulated manner in a water reservoir with an internal corrosion protection coating, in such a way that corrosion in the hot water reservoir is largely avoided.
  • the cladding tube of the electric heating insert is made of an anodic passivable metal and can be electrically anodized for passivation.
  • the anodically passivatable metal is preferably titanium, niobium or tantalum.
  • the invention uses an anodically passivable metal instead of the previously anodically attackable cladding tube material, such as, for example, copper or nickel alloys, so that the above-mentioned corrosion problems do not occur.
  • Titanium, niobium or tantalum has proven to be a suitable material.
  • a tubular jacket made of titanium z. B. passivates reliably under anodic conditions while maintaining a maximum potential of approximately 12 volts breakdown potential. This value is never exceeded with cathodically protected hot water storage tanks. In order to ensure the anodic passivation with all types of hot water tanks with certainty, it is additionally proposed to apply an anodic charge to the insulated pipe jacket.
  • An electric heating insert 2 is arranged within a water heater 1 and is mounted in an electrically insulated manner in the container wall or in a lid or in a screwing head (reference number 3).
  • the electrical energy for heating preferably alternating current, is fed to the connections 4.
  • Limescale deposits on the electric heating insert 2 are now prevented in the known manner by a DC voltage as follows.
  • a direct current source 5 is connected at location 6 with the positive pole to the cladding tube of the electric heating insert 2 and at location 7 with the negative pole to the container wall.
  • This anodic circuit of the heating element 2 prevents the ions of the hardness formers from being deposited on the heating element 2 and thus prevents the formation of limescale.
  • an additional cathode surface 8 is shown opposite the container wall, on which lime is deposited in a targeted manner. It is particularly necessary for storage with internal enamelling or plastic coating.
  • the cathode surface completely or partially envelops the electric heating element 2 and is connected in an electrically conductive manner to the container wall via the line 9.
  • the limescale can settle on this additional cathode surface, regardless of the geometric shape and surface coating of the container wall.
  • the cathode surface 8 consists of a metal part. As a material for this z. B. normal or galvanized iron can be used. The embodiment has already been described above. These additional cathode surfaces can also consist of bi-metal sheet pieces. In the case of bi-metal sheets, 2 metal sheets with different coefficients of thermal expansion are rolled together. Due to the bending effect under temperature changes, adhering layers of limescale easily crack.
  • Fig. 3 shows an enlarged portion of the hairpin-shaped electric heating insert 2, for example.
  • the double-hatched areas 10, 11 and 12 represent z.
  • B. is platinized patches.
  • B. a spiral 10 or an annular 11 surface arrangement possible.
  • a grid-like embodiment is to be indicated by reference number 12.
  • the areas of the heating element lying between the hatched areas have no noble metal layer, so they consist of an anodically passivatable material such as, for. B. Titan.
  • an external current anode 14 with its part 15 platinum-plated for the protective current outlet is arranged in one of the hot water storage tanks 13 to be removed for corrosion protection.
  • the anode is passed through the container wall in an electrically insulated manner.
  • the protective current is supplied by a direct current source 17 which is connected to the external current anode (reference number 18) with the positive pole and to the container wall (reference number 19) with the negative pole.
  • a direct current source 17 which is connected to the external current anode (reference number 18) with the positive pole and to the container wall (reference number 19) with the negative pole.
  • the water can be heated via heating coils or a double jacket (not shown in the drawing), the heating medium being removed, for example, from boilers or heat pumps. Additionally or alternatively, the hot water is heated by an electric heating element 20, the electrically insulated installation of which in the hot water tank 13 takes place in the area of the reference numeral 21.
  • the electrical energy for heating the hot water is supplied to the connections 22 as an alternating or three-phase current.
  • the tubular casing of the electric heating element 20 which is made of titanium, for example, the tubular casing is connected to the positive pole of the direct current source 17 parallel to the external current anode 14 (connection 23).

Abstract

1. Water heaters, in particular storage water heaters, instantaneous water heaters, water boilers, having an electric heating element which is connected to AC current and has a jacket pipe of an anodically passivatable material coated with a precious metal of the platinum series, said electric heating element being fitted in an electrically insulated manner in the wall of the tank, and said electric heating element being connected anodically and said tank wall cathodically to a DC source, characterized in that surfaces coated with precious metal and surfaces not coated with precious metal are distributed evenly over said jacket pipe (2) of said electric heating element in accordance with a geometric pattern (10, 11, 12).

Description

Die Erfindung bezieht sich zum einen auf einen Wassererhitzer wie z. B. Warmwasserspeicher, Durchlauferhitzer, Kochendwassergerät mit einem Elektroheizeinsatz und zum anderen auf Elektroheizkörper in Wassererhitzern wie Warmwasserspeichern mit Innen-Korrosionsschutz-Beschichtung.The invention relates on the one hand to a water heater such. B. hot water tank, instantaneous water heater, boiling water device with an electric heating insert and on the other hand on electric radiators in water heaters such as hot water tanks with an internal corrosion protection coating.

Wassererhitzer, wie z. B. Warmwasserspeicher, Durchlauferhitzer, Haushaltsgeräte, chemisch-technische Apparate u. a., die mit Elektroheizeinsätzen beheizt werden, sind je nach Wasserhärte durch Kalkablagerungen auf den Heizstäben infolge Überhitzung gefährdet.Water heaters such as B. hot water tank, water heater, household appliances, chemical-technical apparatus and. a., which are heated with electric heating inserts, are at risk from limescale deposits on the heating elements due to overheating, depending on the water hardness.

Es sind Vorschläge bekannt, durch Ausnutzung des elektrolytischen Dissoziationseffektes die Ablagerung der Härtebildner am Elektroheizstab zu verhindern: Durch Anlegung einer Gleichspannung zwischen Heizstab und Behälterwandung -wobei das Hüllrohr des Heizstabes als Anode und die Behälterwandung als Kathode geschaltet ist- werden die Ionen der Härtebildner bevorzugt an der Behälterwand abgelagert. Zur Verhinderung von Abtragsverlusten muß das Hüllrohr des Elektroheizeinsatzes dabei aus einem anodisch passivierbarem Material bestehen, wie z. B. Titan, Tantal oder Niob. Das Hüllrohr muß auf der Außenfläche zusätzlich zur Gewährleistung eines ausreichenden Stromüberganges mit einer dünnen Edelmetallschicht aus der Platinreihe überzogen sein (DE-OS 31 05 922). Eine Aufgabe der vorliegenden Erfindung ist es, einen Wassererhitzer wie z. B. Warmwasserspeicher, Durchlauferhitzer, Kochendwassergerät mit einem Elektroheizeinsatz umfassend ein Hüllrohr aus einem anodisch passivierbarem Material mit einer Beschichtung mit einem Edelmetall aus der Platinreihe so weiterzubilden, daß ein material- und damit kostengünstiger Schutz des Elektroheizeinsatzes gegen Kalkablagerungen erfolgt. Die Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Edelmetallschicht zur Ausbildung von beschichtungsfreien Stellen in beliebigen geometrischen Mustern auf dem Hüllrohr des Heizstabes aufgetragen ist. Vorzugsweise bilden die Edelmetallschichtflächen ein regelmäßig wiederkehrendes geometrisches Muster.Proposals are known to prevent the deposition of hardness on the electric heating element by utilizing the electrolytic dissociation effect: By applying a direct voltage between the heating element and the container wall - whereby the jacket tube of the heating element is connected as the anode and the container wall as the cathode - the ions of the hardness elements are preferentially turned on the container wall is deposited. To prevent erosion losses, the cladding tube of the electric heating insert must consist of an anodically passivatable material, such as, for. B. titanium, tantalum or niobium. The cladding tube must be coated on the outer surface in addition to ensure a sufficient current transfer with a thin layer of noble metal from the platinum series (DE-OS 31 05 922). An object of the present invention is to provide a water heater such as. B. hot water storage tank, instantaneous water heater, boiling water device with an electric heating insert comprising a cladding tube made of an anodically passivatable material with a coating with a noble metal from the platinum series so that a material and thus inexpensive protection of the electric heating insert against limescale takes place. The object is achieved in that the precious metal layer is applied to form coating-free spots in any geometric pattern on the cladding tube of the heating element. The noble metal layer surfaces preferably form a regularly recurring geometric pattern.

Erfindungsgemäß werden demzufolge bereichsweise Edelmetallschichten, also z. B. platinierte und nicht platinierte Flächen gleichmäßig über die gesamte Oberfläche des Heizstabes verteilt. Dadurch kann sich der nachstehend beschriebene elektro-chemische Effekt für den Kalkschutz der nicht mit dem Edelmetall beschichteten Flächen ausgenutzt werden. An der Anode d. h. am Elektroheizstab entsteht aus den hier abgeschiedenen Hydrogenkarbonat-Ionen Kohlensäure. Letztere löst eine an den platinfreien Stellen sich bildende Calzium- bzw. Magnesiumkarbonat-Schicht sofort wieder auf. Insbesondere bei einem Flächenverhältnis von Titanfläche zu Platinfläche von 1: bis 2:1 ist dieser Effekt voll wirksam, wobei der Abstand der platinierten Flächen ca. 1-2 cm betragen kann.According to the invention, areas of noble metal, ie, e.g. B. platinized and non-platinized surfaces evenly distributed over the entire surface of the heating element. As a result, the electro-chemical effect described below can be used for the limescale protection of the surfaces not coated with the precious metal. At the anode d. H. Carbonic acid is formed on the electric heating rod from the hydrogen carbonate ions that are separated here. The latter immediately dissolves a calcium or magnesium carbonate layer that forms on the platinum-free areas. This effect is particularly effective with an area ratio of titanium area to platinum area of 1: to 2: 1, the distance between the platinized areas being approximately 1-2 cm.

Bei dieser Gestaltung der Heizstab-Oberfläche wird durch Einsparung von z. B. Platinmetall oder einem anderen Edelmetall eine im Vergleich zum Stand der Technik erheblich kostengünstigere Herstellung der kalkgeschützten Elektroheizeinsätze erreicht.In this design of the heater surface is saved by saving z. B. platinum metal or another noble metal achieved in comparison to the prior art considerably cheaper production of lime-protected electric heating inserts.

Die edelmetallschichtfreien Bereiche können durch Aufwickeln von Abdeckbändern spiralförmig oder ringförmig beim Aufbringen der Platinschicht erhalten werden, ebenso durch Kunstharzauftrag oder Abdeckmasken.The areas free of the precious metal layer can be obtained by winding covering tapes in a spiral or ring shape when the platinum layer is applied, as well as by applying synthetic resin or covering masks.

Es kann sich ferner als zweckmäßig erweisen, eine zusätzliche kathodische Fläche mantelförmig um den Heizstab herum anzuordnen. Als Blechmantel z. B. kann die Fläche geschlossen oder segmentförmig ausgeführt sein. Sie kann aber auch aus einem Metalldrahtnetz, aus Metallstäben, oder aus einem gelochten Streckmetallgitter bestehen.It may also prove expedient to arrange an additional cathodic surface in the form of a jacket around the heating element. As a sheet metal z. B. the surface can be closed or segmented. But it can also consist of a metal wire mesh, metal rods, or a perforated expanded metal grid.

Ferner bezieht sich die Erfindung auf einen Elektroheizeinsatz mit kathodischem Korrosionsschutz, der elektrisch isoliert in einem Wasserspeicher mit Innenkorrosionsschutzbeschichtung eingebaut ist.Furthermore, the invention relates to an electric heating insert with cathodic corrosion protection, which is installed in an electrically insulated manner in a water reservoir with an internal corrosion protection coating.

Warmwasserspeicher, beispielsweise mit emaillierter Innenwandung werden zur Verhütung von Korrosion kathodisch durch Opferanoden oder Fremdstromanoden geschützt. Werden solche Speicher zusätzlich mit Elektroheizkörpern elektrisch beheizt, so entstehen folgende Schwierigkeiten: Durch Einbeziehung des Heizkörpers mit seiner blanken Metalloberfläche in die kathodisch geschützte Behälterwandung stellt sich bei Magnesium-Opferanoden ein zu hoher Magnesiumverbrauch ein bzw. es wird -ebenso bei Fremdstromanoden (Inert-Anoden)- an bestimmten Wandungsstellen des Speichers durch Schattenwirkung oder Schutzstromabsaugung durch den Elektroheizkörper kein ausreichendes negatives Schutzpotential erreicht. Abhilfe wurde zwar dadurch gefunden, daß die Elektroheizkörper elektrisch isoliert in die Behälterwandung eingebaut wurden, gleichzeitig trat aber damit ein zusätzliches Problem auf: Es stellte sich heraus, daß durch Lochfraß-Korrosion am Hüllrohr des Elektroheizkörpers dieser oft nach kurzer Betriebszeit zerstört wurde: Durch anodische Aufladung des isolierten Hüllrohres (Rohrmantel) findet im Bereich des Stromaustrittes in das Wasser anodisch eine Metallkorrosion statt. Dies erfolgt verstärkt als Lochfraß am metallischen Einschraubkopf bzw. durch in der Nähe befindliche Emaille-Fehlstellen.Hot water storage tanks, for example with enamelled inner walls, are cathodically protected by sacrificial anodes or external current anodes to prevent corrosion. If such stores are additionally electrically heated with electric radiators, the following difficulties arise: Including the radiator with its bare metal surface in the cathodically protected container wall results in excessive magnesium consumption in the case of magnesium sacrificial anodes or in the case of external current anodes (inert anodes) ) - At certain wall locations of the storage tank, sufficient negative protection potential has not been achieved due to the shadow effect or protective current extraction by the electric heater. A remedy was found by installing the electric radiators in the container wall in an electrically insulated manner, but at the same time an additional problem arose: It turned out that pitting corrosion on the tubular casing of the electric radiator was often destroyed after a short period of operation: by anodic The insulated cladding tube (tube jacket) is anodically charged with metal corrosion in the area of the current outlet into the water. This occurs increasingly as pitting on the metal screw-in head or due to nearby enamel defects.

Es wurde versucht, durch folgende Maßnahmen Korrosions-Störfälle dieser Art zu vermeiden: Einbau eines elektrischen Widerstandes zwischen Heizkörper-Hüllrohr und Behälterwandung. Durch diese Maßnahme wird das Rohr des Elektroheizkörpers abgeschwächt an den kathodischen Schutzkreis angeschlossen. Nachteilig hierbei ist allerdings, daß der Widerstand je nach örtlichen Wasserverhältnissen (Leitfähigkeit) auf bestimmte Widerstandswerte eingestellt werden muß, wobei der ursprünglich erwünschte Isolationseffekt teilweise wieder aufgehoben wird.An attempt was made to avoid this type of corrosion malfunction by the following measures: Installation of an electrical resistance between the radiator cladding tube and the tank wall. This measure weakens the tube of the electric radiator to the cathodic protection circuit. The disadvantage here is that the resistance depending according to local water conditions (conductivity) must be set to certain resistance values, whereby the originally desired insulation effect is partially canceled.

Als weitere Maßnahme zur Korrosionsverhinderung wurde der metallische Einschraubkopf des Elektroheizkörpers mit isolierendem Kunststoff beschichtet. Auch dies ist problematisch, da bekanntlich auch hochwertige Kunststoffe unter Warmwasserbedingungen keine Dauerbeständigkeit aufweisen.As a further measure to prevent corrosion, the metal screw-in head of the electric radiator was coated with insulating plastic. This is also problematic since, as is well known, even high-quality plastics do not have long-term durability under hot water conditions.

Eine weitere Aufgabe der vorliegenden Erfindung ist es, einen Elektroheizeinsatz mit kathodischem Korrosionsschutz, der elektrisch isoliert in einem Wasserspeicher mit Innen-Korrosionsschutz-Beschichtung eingebaut ist, so auszubilden, daß Korrosionen im Warmwasserspeicher weitgehend vermieden werden.A further object of the present invention is to design an electric heating insert with cathodic corrosion protection, which is installed in an electrically insulated manner in a water reservoir with an internal corrosion protection coating, in such a way that corrosion in the hot water reservoir is largely avoided.

Die Aufgabe wird erfindungsgemäß dadurch gelöst, daß das Hüllrohr des Elektroheizeinsatzes aus einem anodisch passivierbarem Metall hergestellt ist und zur Passivierung elektrisch anodisch beaufschlagbar ist. Insbesondere ist das anodisch passivierbare Metall vorzugsweise Titan, Niob oder Tantal.The object is achieved in that the cladding tube of the electric heating insert is made of an anodic passivable metal and can be electrically anodized for passivation. In particular, the anodically passivatable metal is preferably titanium, niobium or tantalum.

Durch die Erfindung wird an Stelle von dem bisher verwendeten anodisch angreifbaren Hüllrohrmaterial, wie zum Beispiel Kupfer- oder Nickellegierungen, ein anodisch passivierbares Metall verwendet, so daß die zuvor angeführten Korrosionsprobleme nicht auftreten. Als hierfür geeignetes Material hat sich Titan, Niob oder Tantal erwiesen. Ein Rohrmantel aus Titan z. B. passiviert sich zuverlässig unter anodischen Bedingungen bei Einhaltung eines maximalen Potentiales von ca. 12 Volt Durchbruchspotential. Dieser Wert wird bei den kathodisch geschützten Warmwasserspeichern niemals überschritten. Um die anodische Passivierung bei allen Bauarten der Warmwasserbehälter mit Sicherheit zu gewährleisten, wird zusätzlich vorgeschlagen, den isolierten Rohrmantel elektrisch anodisch zu beaufschlagen. Dies kann bei Inert-Anoden-Systemen zum Beispiel in einfacher Weise durch einen parallelen elektrischen Anschluß an den Pluspol des dort vorhandenen Potentiostaten erfolgen. Als besonders vorteilhaft erweist es sich, die Stromquelle im Anschlußkopf des Elektroheizkörpers anzuordnen.The invention uses an anodically passivable metal instead of the previously anodically attackable cladding tube material, such as, for example, copper or nickel alloys, so that the above-mentioned corrosion problems do not occur. Titanium, niobium or tantalum has proven to be a suitable material. A tubular jacket made of titanium z. B. passivates reliably under anodic conditions while maintaining a maximum potential of approximately 12 volts breakdown potential. This value is never exceeded with cathodically protected hot water storage tanks. In order to ensure the anodic passivation with all types of hot water tanks with certainty, it is additionally proposed to apply an anodic charge to the insulated pipe jacket. In the case of inert anode systems, this can be done, for example, in a simple manner by means of a parallel one electrical connection to the positive pole of the existing potentiostat. It has proven to be particularly advantageous to arrange the current source in the connection head of the electric heating element.

Weitere Einzelheiten, Vorteile und Merkmale der Erfindung sind der beigefügten Zeichnung zu entnehmen, in der bevorzugte Ausführungsbeispiele dargestellt sind.Further details, advantages and features of the invention can be found in the accompanying drawing, in which preferred exemplary embodiments are shown.

Es zeigen:

  • Fig. 1 einen Wassererhitzer im Längsschnitt,
  • Fig. 2 eine Schnittdarstellung des Wassererhitzers nach Fig. 1 entlang der Linie II-II,
  • Fig. 3 eine vergrößerte Darstellung eines Elektroheizeinsatzes und
  • Fig. 4 einen Warmwasserspeicher mit kathodischem Korrosionsschutz im Längsschnitt.
Show it:
  • 1 shows a water heater in longitudinal section,
  • 2 is a sectional view of the water heater of FIG. 1 along the line II-II,
  • Fig. 3 is an enlarged view of an electric heater and
  • Fig. 4 shows a hot water tank with cathodic protection against corrosion in longitudinal section.

Innerhalb eines Wassererhitzers 1 ist ein Elektroheizeinsatz 2 angeordnet, der in der Behälterwandung bzw. in einem Deckel oder in einem Verschraubungskopf elektrisch isoliert gelagert ist (Bezugszeichen 3). Die elektrische Energie zur Beheizung, vorzugsweise Wechselstrom, wird den Anschlüssen 4 zugeführt.An electric heating insert 2 is arranged within a water heater 1 and is mounted in an electrically insulated manner in the container wall or in a lid or in a screwing head (reference number 3). The electrical energy for heating, preferably alternating current, is fed to the connections 4.

Eine Kalkablagerung an dem Elektroheizeinsatz 2 wird nun wie folgt in bekannter Weise durch eine Gleichstromspannung verhindert. So ist eine Gleichstromquelle 5 am Ort 6 mit dem Pluspol an das Hüllrohr des Elektroheizeinsatzes 2 und am Ort 7 mit dem Minuspol an die Behälterwand angeschlossen. Durch diese anodische Schaltung des Heizstabes 2 wird die Ablagerung der Ionen der Härtebildner am Heizstab 2 und damit die Kalkschichtbildung verhindert.Limescale deposits on the electric heating insert 2 are now prevented in the known manner by a DC voltage as follows. Thus, a direct current source 5 is connected at location 6 with the positive pole to the cladding tube of the electric heating insert 2 and at location 7 with the negative pole to the container wall. This anodic circuit of the heating element 2 prevents the ions of the hardness formers from being deposited on the heating element 2 and thus prevents the formation of limescale.

In den Fig. 1 und 2 ist eine gegenüber der Behälterwand zusätzliche Kathodenfläche 8 dargestellt, an der gezielt Kalk abgelagert wird. Sie ist besonders bei Speichern mit Innenemaillierung oder Kunststoffbeschichtung erforderlich.1 and 2, an additional cathode surface 8 is shown opposite the container wall, on which lime is deposited in a targeted manner. It is particularly necessary for storage with internal enamelling or plastic coating.

Die Kathodenfläche umhüllt je nach Behälterausführung den Elektroheizstab 2 ganz oder teilweise und ist über die Leitung 9 mit der Behälterwandung elektrisch leitend verbunden. An dieser zusätzlichen Kathodenfläche kann sich, unabhängig von der geometrischen Form und Oberflächenbeschichtung der Behälterwandung der Kalkbildner absetzen.Depending on the container design, the cathode surface completely or partially envelops the electric heating element 2 and is connected in an electrically conductive manner to the container wall via the line 9. The limescale can settle on this additional cathode surface, regardless of the geometric shape and surface coating of the container wall.

Die Kathodenfläche 8 besteht aus einem Metallteil. Als Material hierfür kann z. B. normales oder verzinktes Eisen verwendet werden. Die Ausführungsform wurde vorstehend bereits beschrieben. Diese zusätzlichen Kathodenflächen können ferner aus Bi-Metall-Blechstücken bestehen. Bei Bi-Metallblechen sind 2 Metallbleche von verschiedenem thermischen Ausdehnungskoeffizienten zusammengewalzt. Durch den Biegungseffekt unter Temperaturwechsel platzen anhaftende Kalkschichten leicht ab.The cathode surface 8 consists of a metal part. As a material for this z. B. normal or galvanized iron can be used. The embodiment has already been described above. These additional cathode surfaces can also consist of bi-metal sheet pieces. In the case of bi-metal sheets, 2 metal sheets with different coefficients of thermal expansion are rolled together. Due to the bending effect under temperature changes, adhering layers of limescale easily crack.

Fig. 3 zeigt ein vergrößertes Teilstück des beispielsweise haarnadelförmigen Elektroheizeinsatzes 2. Die doppelschraffierten Flächen 10, 11 und 12 stellen aus Edelmetall bestehende z. B. platinierte Flächenstücke dar. So ist z. B. eine spiralförmige 10 oder eine ringförmige 11 Flächenanordnung möglich. Durch das Bezugszeichen 12 soll eine rasterförmige Ausführungsart angedeutet sein. Die zwischen den schraffierten Stellen liegenden Flächenteile des Heizstabes weisen keine Edelmetallschicht auf, bestehen also aus einen anodisch passivierbaren Material wie z. B. Titan.Fig. 3 shows an enlarged portion of the hairpin-shaped electric heating insert 2, for example. The double-hatched areas 10, 11 and 12 represent z. B. is platinized patches. B. a spiral 10 or an annular 11 surface arrangement possible. A grid-like embodiment is to be indicated by reference number 12. The areas of the heating element lying between the hatched areas have no noble metal layer, so they consist of an anodically passivatable material such as, for. B. Titan.

In einem der Fig. 4 zu entnehmenden Warmwasserspeicher 13 ist zum Korrosionsschutz beispielsweise eine Fremdstromanode 14 mit ihrem für den Schutzstromaustritt platinierten Teil 15 angeordnet. Die Anode ist am Ort 16 elektrisch isoliert durch die Behälterwandung geführt. Die Versorgung mit Schutzstrom erfolgt durch eine Gleichstromquelle 17, die mit dem Pluspol an die Fremdstromanode (Bezugszeichen 18) und mit dem Minuspol an die Behälterwandung (Bezugszeichen 19) angeschlossen ist. Ein zur Regelung des Korrosionsschutzes im allgemeinen erforderlicher Potentiostat einschließlich einer Bezugselektrode ist in der Zeichnung nicht dargestellt.For example, an external current anode 14 with its part 15 platinum-plated for the protective current outlet is arranged in one of the hot water storage tanks 13 to be removed for corrosion protection. At location 16, the anode is passed through the container wall in an electrically insulated manner. The protective current is supplied by a direct current source 17 which is connected to the external current anode (reference number 18) with the positive pole and to the container wall (reference number 19) with the negative pole. One for Control of the corrosion protection in general required potentiostat including a reference electrode is not shown in the drawing.

Bei dem Warmwasserspeicher 13 kann die Aufheizung des Wassers über Heizschlangen oder Doppelmantel (in der Zeichnung nicht dargestellt) erfolgen, wobei das Heizmedium beispielsweise aus Heizkesseln oder Wärmepumpen entnommen wird. Zusätzlich oder auch alternativ erfolgt die Aufheizung des Warmwassers durch einen Elektroheizkörper 20, dessen elektrisch isolierter Einbau in den Warmwasserspeicher 13 im Bereich des Bezugszeichens 21 erfolgt.In the hot water tank 13, the water can be heated via heating coils or a double jacket (not shown in the drawing), the heating medium being removed, for example, from boilers or heat pumps. Additionally or alternatively, the hot water is heated by an electric heating element 20, the electrically insulated installation of which in the hot water tank 13 takes place in the area of the reference numeral 21.

Die elektrische Energie zur Aufheizung des Warmwassers wird als Wechsel-oder Drehstrom dem Heizkörper 20 den Anschlüssen 22 zugeführt. Zur anodischen Passivierung des beispielsweise aus Titan bestehenden Rohrmantels des Elektroheizkörpers 20 wird der Rohrmantel parallel zur Fremdstromanode 14 mit dem Pluspol der Gleichstromquelle 17 verbunden (Anschluß 23).The electrical energy for heating the hot water is supplied to the connections 22 as an alternating or three-phase current. For the anodic passivation of the tubular casing of the electric heating element 20, which is made of titanium, for example, the tubular casing is connected to the positive pole of the direct current source 17 parallel to the external current anode 14 (connection 23).

Claims (9)

1. Wassererhitzer (1) wie z.B. Warmwasserspeicher, Durchlauferhitzer, Kochendwassergerät mit einem Elektroheizeinsatz umfassend ein Hüllrohr aus einem anodisch passivierbarem Material mit einer Beschichtung mit einem Edelmetall aus der Platinreihe,
dadurch gekennzeichnet,
daß die Edelmetallschicht zur Ausbildung von beschichtungsfreien Stellen in beliebigen geometrischen Mustern (10, 11, 12) auf dem Hüllrohr des Heizstabes (2) aufgetragen ist.1. water heater (1), such as a hot water tank, instantaneous water heater, boiling water device with an electric heating insert, comprising a cladding tube made of an anodically passivable material with a coating with a noble metal from the platinum series,
characterized,
that the noble metal layer to form coating-free spots in any geometric pattern (10, 11, 12) is applied to the cladding tube of the heating element (2). 2. Wassererhitzer nach Anspruch 1, dadurch gekennzeichnet,
daß die Edelmetallschichtflächen (10, 11, 12) ein regelmäßig wiederkehrendes geometrisches Muster bilden.2. Water heater according to claim 1, characterized in
that the precious metal layer surfaces (10, 11, 12) form a regularly recurring geometric pattern. 3. Wassererhitzer nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet,
daß das Flächenverhältnis von dem anodisch passivierbaren Material zu der Edelmetallschicht (10, 11, 12) vorzugsweise 1:1 bis 2:1 beträgt.3. Water heater according to claim 1 or claim 2, characterized in
that the area ratio of the anodically passivatable material to the noble metal layer (10, 11, 12) is preferably 1: 1 to 2: 1. 4. Wassererhitzer nach zumindest einem der vorhergehenden Ansprüche, dadurch gekennzeichnet,
daß die bereichsweise aufgetragenen Flächen (10, 11, 12) des Edelmetalls von Fläche zu Fläche einen Abstand von in etwa 1-2 cm aufweisen.4. Water heater according to at least one of the preceding claims, characterized in that
that the areas (10, 11, 12) of the noble metal which have been applied in regions are at a distance of approximately 1-2 cm from surface to surface. 5. Wassererhitzer nach Anspruch 1, dadurch gekennzeichnet,
daß der Elektroheizeinsatz (2) zusätzlich mit einer Kathodenfläche (8) innerhalb des Wasserbehälters (1) ganz oder teilweise umhüllt ist.5. Water heater according to claim 1, characterized in
that the electric heating insert (2) is additionally completely or partially encased with a cathode surface (8) inside the water container (1). 6. Wassererhitzer nach Anspruch 5, dadurch gekennzeichnet,
daß die Kathodenfläche (8) aus einem Bi-Metall besteht.6. Water heater according to claim 5, characterized in
that the cathode surface (8) consists of a bimetal. 7. Elektroheizkörper für Wassererhitzer wie Warmwasserspeicher mit kathodischem Korrosionsschutz, der elektrisch isoliert in einem Wasserspeicher (13) eingebaut ist,
dadurch gekennzeichnet, daß das Hüllrohr des Elektroheizkörpers (20) aus einem anodisch passivierbarem Metall hergestellt ist.7. electric radiators for water heaters such as hot water tanks with cathodic corrosion protection, which is installed in an electrically insulated manner in a water tank (13),
characterized in that the cladding tube of the electric heater (20) is made of an anodic passivable metal. 8. Elektroheizkörper nach Anspruch 7, dadurch gekennzeichnet,
daß das anodisch passivierbare Metall vorzugsweise Titan, Niob oder Tantal ist.8. Electric heater according to claim 7, characterized in
that the anodically passivatable metal is preferably titanium, niobium or tantalum. 9. Elektroheizkörper nach Anspruch 7 oder 8, dadurch gekennzeichnet,
daß das Hüllrohr des elektrisch isoliert eingebauten Elektroheizkörpers (20) durch elektrischen Anschluß an den Pluspol einer Gleichstromquelle (17) anodisch passivierbar ist.9. Electric heater according to claim 7 or 8, characterized in
that the cladding tube of the electrically insulated electric heating element (20) can be anodically passivated by electrical connection to the positive pole of a direct current source (17).
EP85102625A 1984-03-09 1985-03-08 Water heater Expired EP0156221B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85102625T ATE48690T1 (en) 1984-03-09 1985-03-08 WATER HEATER.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE19848407212 DE8407212U1 (en) 1984-03-09 1984-03-09 WATER HEATER WITH ELECTRIC HEATING INSERT
DE8407212U 1984-03-09
DE8408655U 1984-03-21
DE19848408655 DE8408655U1 (en) 1984-03-21 1984-03-21 ELECTRIC RADIATOR WITH INSULATED COUPLING IN HOT WATER STORAGE

Publications (3)

Publication Number Publication Date
EP0156221A2 true EP0156221A2 (en) 1985-10-02
EP0156221A3 EP0156221A3 (en) 1987-05-27
EP0156221B1 EP0156221B1 (en) 1989-12-13

Family

ID=25949871

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85102625A Expired EP0156221B1 (en) 1984-03-09 1985-03-08 Water heater

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EP (1) EP0156221B1 (en)
DE (1) DE3574769D1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2639961A1 (en) * 1988-11-28 1990-06-08 Lobry Andre Device for protecting surfaces in contact with liquid against scaling or corrosion
DE4008329C1 (en) * 1990-03-15 1991-05-02 Norsk Hydro Magnesiumgesellschaft Mbh, 4250 Bottrop, De Electric water heater - has resistance heater embedded in electrically insulating material, esp. magnesium oxide
FR2657089A1 (en) * 1990-01-16 1991-07-19 Lobry Andre Protection against scaling and corrosion of surfaces in contact with liquids
WO2004108992A1 (en) * 2003-06-03 2004-12-16 Titanium Metals Corporation Fabricated titanium article having improved corrosion resistance

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3012958A (en) * 1958-04-17 1961-12-12 Patrol Valve Co Vitreous lined water tanks with sacrificial anodes
DE1258704B (en) * 1955-02-01 1968-01-11 Dow Chemical Co Galvanic anode for the cathodic protection of metal surfaces
DE3105922A1 (en) * 1981-02-18 1982-09-09 Buderus Ag, 6330 Wetzlar Water heater with an electrical heating element connected to alternating current

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1258704B (en) * 1955-02-01 1968-01-11 Dow Chemical Co Galvanic anode for the cathodic protection of metal surfaces
US3012958A (en) * 1958-04-17 1961-12-12 Patrol Valve Co Vitreous lined water tanks with sacrificial anodes
DE3105922A1 (en) * 1981-02-18 1982-09-09 Buderus Ag, 6330 Wetzlar Water heater with an electrical heating element connected to alternating current

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2639961A1 (en) * 1988-11-28 1990-06-08 Lobry Andre Device for protecting surfaces in contact with liquid against scaling or corrosion
FR2657089A1 (en) * 1990-01-16 1991-07-19 Lobry Andre Protection against scaling and corrosion of surfaces in contact with liquids
DE4008329C1 (en) * 1990-03-15 1991-05-02 Norsk Hydro Magnesiumgesellschaft Mbh, 4250 Bottrop, De Electric water heater - has resistance heater embedded in electrically insulating material, esp. magnesium oxide
WO2004108992A1 (en) * 2003-06-03 2004-12-16 Titanium Metals Corporation Fabricated titanium article having improved corrosion resistance

Also Published As

Publication number Publication date
EP0156221A3 (en) 1987-05-27
DE3574769D1 (en) 1990-01-18
EP0156221B1 (en) 1989-12-13

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