Fuel cell system glow plug and method of forming same
A method of sealing a glow plug of a fuel cell system, the glow plug including a housing and a heating element extending from a first end of the housing. The method includes inserting the heating element into a sealing element having an annular base and a tubular collar extending from the base and forming a fluid-tight connection between the glow plug and the fuel cell system by attaching the collar to the heating element and by attaching the base to the first end of the housing.
1. A solid oxide fuel cell system comprising:
a hot box housing containing a reaction chamber;
a fuel cell stack disposed in the hot box housing; and
a glow plug extending through an opening of the hot box housing into the reaction chamber, wherein the glow plug comprises:
a housing having a threaded first end which is mated with a threaded portion of the hot box housing;
a heating element disposed in the housing and having a working end extending from the threaded first end of the housing into the reaction chamber, such that the working end of the heating element is exposed in the reaction chamber outside of the threaded first end of the housing; and
a sealing element disposed entirely outside of the housing, wherein the sealing element is located entirely outside the threaded first end of the housing and inside the reaction chamber in the hot box housing, and wherein the sealing element forms a fluid-tight connection between the threaded first end of the housing and the exposed working end of the heating element, the sealing element comprising:
an annular base attached to an outer surface of the threaded first end of the housing by brazing or welding; and
a tubular collar extending from the base and attached to the exposed working end of the heating element by brazing or welding,
wherein the sealing element is formed from a sheet of metal that is bent such that the sealing element is curved where the collar and the base are connected, the base extends orthogonally from the collar, and a thickness of the base is the same as a thickness of the collar.
2. The solid oxide fuel cell system of claim 1 , wherein the sealing element is attached to the housing and heating element by laser welding.
3. The solid oxide fuel cell system of claim 1 , wherein the sealing element is attached to the housing and heating element by an activated brazing alloy gold braze.
4. The solid oxide fuel cell system of claim 1 , wherein the sealing element comprises an austenitic nickel-chromium alloy.
5. The solid oxide fuel cell system of claim 1 , further comprising a landing pad disposed in the housing, the landing pad comprising a landing pad collar attached to the heating element and a lead connection extending from the collar.
6. The solid oxide fuel cell system of claim 5 , wherein the landing pad comprises a nickel-silicon alloy.
7. The solid oxide fuel cell system of claim 6 , further comprising a lead wire attached to the lead connection using an activated brazing alloy gold braze, the lead wire comprising a nickel-silicon alloy.
8. The solid oxide fuel cell system of claim 5 , further comprising a lead wire comprising a nickel-silicon alloy and having a flattened end, the flattened end being attached to the heating element using an activated brazing alloy gold braze.
9. The solid oxide fuel cell system of claim 5 , further comprising a center lead wire attached to the heating element using an activated brazing alloy gold braze.
10. The solid oxide fuel cell system of claim 5 , wherein the landing pad collar extends orthogonally from the lead connection.
11. The solid oxide fuel cell system of claim 5 , wherein the heating element comprises a ceramic material.