Heating solid oxide for fuel cell stack

A solid oxide fuel cell system comprising

• (a) at least one tubular solid oxide fuel cell comprising a ceramic solid state electrolyte layer and inner and outer electrode layers concentrically arranged around and sandwiching the electrolyte layer, the inner electrode layer fluidly communicable with only one of an oxidant reactant and a fuel reactant, and the outer electrode layer fluidly communicable with only the other of the oxidant and fuel reactants;
• and
• (b) a combustion heater comprising a first tube, a dense second tube within the first tube, and a porous third tube inside the second tube, an annular space in between the second and third tubes defining a combustion air chamber, and an inside of the third tube defining a combustion fuel chamber, the combustion air chamber fluidly communicable with the oxidant and the combustion fuel chamber fluidly communicable with the fuel, the third tube sufficiently porous to enable the fuel and air reactants to pass through the third tube such that combustion can occur, and an annular space between the first and second tubes defining a reactant heating chamber fluidly communicable with one of the oxidant reactant and the fuel reactant and thermally coupled to the combustion air chamber such that heat generated from the combustion is transferable to the reactant inside the reactant heating chamber.

A solid oxide fuel cell system comprising:

• (a) at least one tubular solid oxide fuel cell comprising a ceramic solid state electrolyte layer and inner and outer electrode layers concentrically arranged around and sandwiching the electrolyte layer, the inner electrode layer fluidly communicable with only one of an oxidant reactant and a fuel reactant, and the outer electrode layer fluidly communicable with only the other of the oxidant and fuel reactants;
• and
• (b) a combustion heater comprising a first tube, a dense second tube within the first tube and a porous third tube inside the second tube, an annular space in between the second and third tubes defining a first combustion chamber, and an inside of the third tube defining a second combustion chamber, the first combustion chamber having an exhaust outlet and the second combustion chamber fluidly communicable with the fuel and oxidant, the fuel and oxidant forming a mixture therein that permeates radially through the third tube and into the first combustion chamber for combusting, and an annular space between the first and second tubes defining a reactant heating chamber fluidly communicable with one of the reactants and thermally coupled to the first combustion chamber such that heat generated from the combustion is transferable to the reactant inside the reactant chamber.