Electrically heated steam boiler for generating superheated steam

摘要

A steam boiler for producing superheated steam directly in the boiler from saturated steam being generated therein includes a plurality of vertical sealed high pressure boiler water heating tubes, each provided with an electrical heating element and containing a limited quantity of water, mounted in a boiler water filled well in the bottom wall of the boiler. Energization of the heating element of each sealed tube produces high pressure saturated steam in the tube causing the tube to rise in temperature to generate saturated steam in the boiler from the water in the well. The tubes each have a vertical extent substantially greater than the controlled depth of water in the boiler. The saturated boiler steam is superheated by an elongated, sealed, vertical vessel mounted on the bottom wall of the boiler and extending upwardly into the boiler steam space above the upper ends of the heating tubes. The vessel contains an electric heater and a limited quantity of water for producing high pressure steam therein at a temperature well above the temperature of the saturated steam in the boiler when the heater is energized, whereby heat radiated from the surface of the vessel causes the surrounding saturated boiler steam to be superheated prior to discharge from the boiler.