Abstract: The electrode boiler is provided with an electrical insulator of ceramic material which is provided with a layer of fluoroplastic material to protect against water deposits thereon. The protected layer may be formed of polytetrafluoroethylene and is of a thickness of from 20 to 50 .mu.m.

Abstract: The insulator for mounting the electrode within the vessel of the boiler includes a hollow moulding of fluoroplastic material and a support member for transmitting mechanical forces. The support member is in the form of a hollow tube which is slidably received at opposite ends in an annular recess of the moulding.

Abstract: The electrical steam generator has a pressure vessel in which pairs of trays are disposed one above the other on a vertical riser. The bottom tray of each pair of trays is electrically insulated from the pressure vessel wall and is connected to a power supply while the top trays of each tray pair are electrically connected to the pressure vessel wall through the riser. The trays each have a peripheral overflow edge and are disposed so that water flows over the overflow edge in the form of a film or curtain from the uppermost tray to the tray therebeneath in an alternating manner from the outer peripheral edge to the inner peripheral edge. The generator provides for an increase in the steam generator output for a given tray size. The top tray of each pair of trays may be shaped to have an outer peripheral overflow edge and the bottom tray of each pair may have an inner peripheral overflow edge.

Abstract: An electrical steam generator includes a plurality of spaced trays disposed in a vertical axis within a pressure vessel defining a steam generating chamber. Alternate trays are electrically connected to the pressure vessel while the other trays are electrically insulated therefrom. Each tray has an overflow over which sump a film of water flows downwardly into the next lower tray to sump in the vessel below the trays and from which water is pumped to the uppermost tray. The other trays and vessel are connected to an electrical power source. Each tray is provided with a flat horizontally disposed stilling element at the overflow to calm the water in the tray, a perforated vertical water and steam permeable stilling wall upstream of the overflow and a vertical water impermeable shielding wall downstream of and spaced from the overflow. The spacing of the shielding wall provides a gap with a horizontal dimension greater than the maximum expected thickness of the film of water flowing out of the respective tray.