Annular superheating element for firetube boilers

A method for superheating steam using a superheater element inserted into the firetube of a firetube boiler, said boiler having a burner end opposite an exhaust end, comprising the steps of:

• providing a superheater element having an outer tube concentric about an inner tube, said outer and inner tube each having a return end and a non-return end;
• an inlet manifold connected to the non-return end of said outer tube;
• an outlet manifold connected to the non-return end of said inner tube;
• and a return affixed to the return end of said outer tube, said return having an interior face and a central axis parallel to and shared by the inner and outer tubes;
• wherein the interior face of said return is rotationally symmetric at all angles of rotation about the central axis;
• and wherein a-point of said interior face is raised towards the return end of said inner tube along said central axis without extending into the inner tube introducing saturated steam into said inlet manifold of said element;
• causing said steam to travel within the outer tube towards the exhaust end of said boiler while absorbing heat energy from heated firetube gasses through the wall of the outer tube;
• directing said now superheated steam into said inner tube by means of said return;
• causing said superheated steam to travel within the inner tube towards the burner end of said boiler while losing heat energy to said saturated steam in said outer tube through the wall of saki inner tube;
• and causing said superheated steam to exit said outlet manifold.

A method for retrofitting firetube boilers to superheat steam comprising the steps of:

• (a) providing one or more superheater elements each comprising an outer tube concentric about an inner tube, said outer and inner tube each having a return end and a non-return end;
• an inlet manifold connected to the non-return end of said outer tube;
• an outlet manifold connected to the non-return end of said inner tube and a return affixed to the return end of said outer tube, said return having an interior face and a central axis parallel to and shared by the inner and outer tubes;
• wherein the interior face of said return is rotationally symmetric at all angles of rotation about the central axis;
• and wherein a point of said interior face is raised towards the return end of said inner tube along said central axis without extending into the inner tube (b) providing an existing firetube boiler;
• and (c) inserting said superheater elements into one or more firetubes of the existing firetube boiler.

A method for retrofitting firetube boilers to superheat steam comprising the steps of:

• (a) providing one or more superheater elements each comprising an outer tube concentric about an inner tube, said outer and inner tube each having a return end and a non-return end;
• an inlet manifold connected to the non-return end of said outer tube;
• an outlet manifold connected to the non-return end of said inner tube;
• and a return affixed to the return end of said outer tube, said return having an interior face and a central axis parallel to and shared by the inner and outer tubes;
• wherein the interior face of said return is rotationally symmetric at all angles of rotation about the central axis;
• and wherein a point of said interior face is raised towards the return end of said inner tube along said central axis without extending into the inner tube;
• (b) providing an existing firetube boiler;
• (c) providing one or more choke thimbles;
• (d) inserting said superheater elements into one or more firetubes of the existing firetube boiler;
• and (e) inserting a choke thimble into each firetube of the existing firetube boiler.