Method and apparatus for melting a salt bed in a steam generator

Claim 1

In an underwater vehicle of the type including apparatus for generating steam for propelling same, said apparatus comprising a closed thin-wall container having a void space at its upper end, a meltable salt mixture filling said container below said space, said mixture having substantially zero coefficient of expansion at its solidifying temperature, the solidifying temperature being in excess of 212* F., the outside of said container being in contact with and subjected to water at ambient pressure, means for pressurizing said space to ambient water pressure, whereby the salt mixture, when melted, subjects the inside of said container to ambient water pressure, a steam generating coil within said salt mixture having a water inlet at its lower end and a steam outlet at its upper end adapted to extract heat from the salt mixture and cause it to solidify, first at the bottom of the container, and thereafter in succeeding layers thereabove, the improvements, in combination, comprising: a. a source of electric power for melting said salt mixture disposed at the surface of the water and means for connecting ends of said coil to same, b. said coil having high electrical resistance, whereby it serves as a heating coil, c. said salt mixture being electrically nonconductive, whereby electric current flows only through the coil and maintains it at uniform temperature throughout its length, whereby the entire salt mixture is uniformly raised in temperature.

Claim 3

A method for use with an underwater vehicle of the type including apparatus for generating steam for propelling same, said apparatus comprising a closed thin-wall container having a void space at its upper end, a meltable salt mixture filling said container below said space, said mixture having substantially zero coefficient of expansion at its solidifying temperature, the solidifying temperature being in excess of 212* F., the outside of said container being in contact with and subjected to water at ambient pressure, means for pressurizing said space to ambient water pressure, whereby the salt mixture, when melted, subjects the inside of said container to ambient water pressure, a steam generating coil within said salt mixture having a water inlet at its lower end and a steam outlet at its upper end adapted to extract heat from the salt mixture and cause it to solidify, first at the bottom of the container, and thereafter in succeeding layers thereabove, said coil having high electrical resistance, whereby it serves as a heating coil, said salt mixture being electrically nonconductive whereby current will flow only through the coil and maintain it at uniform temperature throughout its length, whereby said entire salt mixture may be uniformly raised in temperature, said method comprising the step of a. passing an electric current through said coil when the vehicle is at the surface of the water until the salt mixture is melted and raised to a desired temperature.

Claim 4

A method for use with an underwater vehicle of the type including apparatus for generating steam for propelling same, said apparatus comprising a closed thin-wall container having a void space at its upper end, a meltable salt mixture filling said container below said space, said mixture having substantially zero coefficient of expansion at its solidifying temperature, the solidifying temperature being in excess of 212* F., the outside of said container being in contact with and subjected to water at ambient pressure, means for pressurizing said space to ambient water pressure, whereby the salt mixture, when melted, subjects the inside of said container to ambient water pressure, a steam generating coil within said salt mixture having a water inlet at its lower end and a steam outlet at its upper end adapted to extract heat from the salt mixture and cause it to solidify, first at the bottom of the container, and thereafter in succeeding layers thereabove, said coil having high electrical resistance, whereby it serves as a heating coil, said salt mixture being electrically nonconductive whereby current will flow only through the coil and maintain it at uniform temperature throughout its length, whereby said entire salt mixture may be uniformly raised in temperature, said method comprising the step of a. passing an electric current through said coil when the vehicle is at the surface of the water until the salt mixture is melted and raised to a desired temperature.