High temperature sub-critical boiler with steam cooled upper furnace and start-up methods
AssigneeThe Babcock & Wilcox Company
InventorsEric L. Wells, Albert J. Bennett, Jeremy L. Remus
Life of this patent
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Abstract
A boiler is disclosed in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. A steam-cooled circuit includes a steam separator, a primary superheater, and the steam-cooled membrane walls of the upper furnace. During start-up, a diversion path is opened that reduces dry steam flow through the primary superheater and increases dry steam flow through the steam-cooled membrane walls of the upper furnace. This protects the steam-cooled membrane walls from excessive thermal stresses during start-up.
Claims20
A boiler comprising:
- a furnace including burners and steam-cooled membrane walls, the steam-cooled membrane walls comprising pipes sealed by membrane;
- a steam separator having a dry steam outlet;
- a steam-cooled circuit connected to the dry steam outlet of the steam separator, the steam-cooled circuit including at least (i) a primary superheater comprising pipes without membrane and (ii) the steam-cooled membrane walls of the furnace, wherein the steam-cooled membrane walls of the furnace are located downstream of the primary superheater in the steam-cooled circuit;
- and
- startup control circuitry configured to (i) reduce flow to the primary superheater and (ii) divert flow from the dry steam outlet of the steam separator to the steam-cooled membrane walls of the furnace.
A boiler, comprising:
- a furnace including at least one steam-cooled membrane wall, the at least one steam-cooled membrane wall comprising pipes sealed by membrane;
- a steam separator having a dry steam outlet;
- one or more primary superheaters comprising pipes without membrane;
- a steam-cooled circuit running from the dry steam outlet to the one or more primary superheaters and subsequently to the at least one steam-cooled membrane wall of the furnace, and containing one or more reduction valves between the one or more primary superheaters and the at least one steam-cooled membrane wall of the furnace;
- a diversion path running from the dry steam outlet through one or more diversion valves to a location upstream of the at least one steam-cooled membrane wall of the furnace and downstream of the one or more primary superheaters;
- and
- control circuitry for switching dry steam flow from the steam separator through the steam-cooled circuit or the diversion path.
A boiler start-up method for starting a boiler having a steam separator, steam-cooled membrane walls forming at least a portion of a furnace, and a primary superheater interposed in a steam-cooled circuit between a dry steam outlet of the steam separator and the steam-cooled membrane walls, the method comprising:
- reducing dry steam flow through the steam-cooled circuit;
- and
- diverting dry steam flow through a diversion path that runs from the dry steam outlet to a location upstream of the steam-cooled membrane walls of the furnace and downstream of the primary superheater, wherein the diversion path bypasses the primary superheater.
Dependencies are inferred from the claim text.