Method to prevent the formation of incrustations on working electrodes in electrode steam generators or the like and a means for performing the method

• US 4,036,716 A
• Filed: 03/24/1975
• Issued: 07/19/1977
• Est. Priority Date: 04/05/1974
• Status: Expired due to Term

• Current Assignee: Goteborgs Analyslaboratorium AB
• Original Assignee: Goteborgs Analyslaboratorium AB
• Inventors: Hulthe, Peter
• Primary Examiner(s): Tufariello, T. M.
• Application Number:
  US05/561,080
• Time in Patent Office: 848 Days
• Field of Search: 204/196, 204/147, 204/231, 204/DIG. 8
• US Class Current: 205/729
• CPC Class Codes: C02F 1/46104 Devices therefor; Their operating or servicing
• CPC Class Codes: C02F 2201/4613 Inversing polarity
• CPC Class Codes: C02F 2201/4615 Time
• CPC Class Codes: C02F 2201/4616 Power supply
• CPC Class Codes: F22B 1/30 Electrode boilers

Abstract

The present invention relates to electrically heated steam generators and means for preventing and removing incrustations due to hard water in such generators. According to the invention this is achieved by means of a superimposed direct current the polarity of which is periodically changed whereby gas bubbles, mainly carbon dioxide and hydrogen, are generated at the electrodes causing segregation and removing of incrustations on the electrodes, the method and means for feeding of the superimposed direct current being variable.

Claims

1. A method for reducing or eliminating the formation of incrustations of water soluble materials on working electrodes which are immersed in a water bath containing said water soluble materials, said electrodes being connected to a source of alternating current, said improvement comprising the steps of:

adding an auxiliary electrode;

superimposing, between said auxiliary electrode and said working electrodes, a direct current voltage such that a low PH-value is obtained in the water near the working electrodes; and

reversing, periodically, the direct current polarity such that the working electrodes and the auxiliary electrode periodically act as an anode and as a cathode causing the PH-value of the water to vary between acidic and alkaline.

2. A method to reduce or to eliminate respectively the formation of incrustations on working electrodes immersed in a water containing steam generator, said electrodes being connected to a source of alternating current and a source for superimposing the working electrodes a direct current according to claim 1 wherein the direct current is fed to an auxiliary electrode the polarity of which is intermittently changed.

3. A method to reduce or to eliminate respective the formation of incrustations on working electrodes immersed in a water containing steam generator, said electrodes being connected to a source of alternating current and a source for superimposing the working electrodes a direct current according to claim 1 wherein the direct current is superimposed the working electrodes successively from an outer timed source of direct current.

4. A method according to claim 1, wherein the intervals between the changes of polarity are of different length.

5. A method according to claim 4, wherein the polarity is repeatedly changed for short time periods during the cleaning phase between two precipitation phases.

6. A method according to claim 5, wherein the electrode working as a cathode is impressed changes of polarity of short duration and with a greater current density than during the precipitation phase during the cleaning phase.

7. A method to reduce or to eliminate respectively the formation of incrustations on working electrodes immersed in a water containing steam generator, said electrodes being connected to a source of alternating current and a source for superimposing the working electrodes a direct current wherein the superimposed direct current with alternating polarity is fed the working electrodes from an auxiliary electrode preferably centrally positioned in relation to the working electrodes, the direct current flowing from a zero phase and the other phases of an alternating current mains over a rectifier for generating a parasitic flow of direct current dependent on the conditions prevailing in the electrolyte.

8. In a device for the generation of steam utilizing a source of alternating current applied to working electrodes immersed in water, an improvement comprising an apparatus for the reduction of incrustations on said working electrodes, said apparatus comprising:

means for imposing a direct current upon said working electrodes; and

means for periodically reversing the direct current in imposed upon said working electrodes.

13. The apparatus of claim 8 wherein said means for imposing includes rectifier means connected to said alternating current source.

9. In a device for the generation of steam utilizing a source of alternating current to working electrodes immersed in water, an improvement comprising an apparatus for the reduction of incrustations on said working electrodes, said apparatus comprising;

auxiliary means for providing an additional electrode;

means for imposing a direct current between said working electrodes and said auxiliary means; and

means for periodically reversing the direct current imposed between said auxiliary means and said working electrodes.

10. A device according to claim 9, wherein the surface of said auxiliary electrode is smaller than the total surface of the working electrodes.

11. A device according to claim 9 wherein said auxiliary electrode comprises a corrosion resistant material, selected from a group comprising graphite or gold plated copper.

12. In a device for the generation of steam utilizing a source of alternating current applied to working electrodes immersed in water, an improvement comprising an apparatus for the reduction of incrustations on said working electrodes, said apparatus comprising:

means for imposing a direct current upon selected working electrodes;

means for varying which of said working electrodes has said direct current imposed upon it; and

means for periodically reversing the direct current imposed upon said selected working electrodes.