Boiler water blowdown control system
AssigneeChemtreat, Inc.
InventorsDouglas A. Godwin, David A. Johnson
Life of this patent
Estimating the term…
Abstract
The present invention relates to a method for automatically maintaining the concentration of scale forming minerals in boiler water for boiler systems utilizing bimodal feedwater pumps that deliver a substantially constant feedwater flow to the boiler drum when activated. According to the present invention, the feedwater supply pump and blowdown rate control valve are synchronized to remove boiler water at a predetermined rate when the feedwater pump is activated. The present invention thereby provides a simplified and less expensive method for controlling the concentration of dissolved solids in boiler water despite variations in the steam loads and/or other boiler operation parameters.
Claims19
A method for controlling a boiler system having a boiler and a feed water assembly arranged and configured to deliver feed water having a known feed water composition to the boiler at a substantially constant feed water rate when activated comprising:
- determining a target blowdown as a percentage of the feed water rate;
- setting a blowdown assembly to remove boiler water from the boiler at a substantially fixed blowdown flow rate when activated, the blowdown flow rate being selected to achieve the target blowdown;
- monitoring a first boiler system parameter;
- activating in a substantially simultaneous manner the feed water assembly and the blowdown assembly at a first predetermined value of the parameter;
- and
- deactivating in a substantially simultaneous manner the feed water assembly and the blowdown assembly at a second predetermined value of the parameter.
A boiler control system comprising:
- a boiler arranged and configured to contain a variable volume of boiler water;
- a feed water source;
- a feed water assembly, the feed water assembly arranged and configured to supply feed water from the feed water source to the boiler at a predetermined and substantially fixed feed water rate when activated and to supply substantially no feed water to the boiler when deactivated;
- and
- a blowdown assembly, the blowdown assembly arranged and configured to remove boiler water from the boiler at a predetermined and substantially fixed blowdown flow rate when activated and remove substantially no boiler water from the boiler when deactivated;
- and
- a blowdown controller arranged and configured to activate the feed water assembly and the blowdown assembly in a substantially simultaneous manner in response to a first predetermnined value of a boiler system parameter and to deactivate the feed water assembly and the blowdown assembly in a substantially simultaneous manner in response to a second predetermined value of the boiler system parameter;
- wherein the blowdown flow rate is a substantially constant percentage of the feed water rate.
A method of operating a boiler system:
- maintaining a boiler water volume within a boiler within a predetermined volume range by adding feed water to the boiler, the feed water being added to the boiler at a predetermined and substantially constant feed water rate during a feed water cycle;
- and
- removing boiler water from the boiler during the feed water cycle at a predetermined and substantially constant blowdown rate, wherein the blowdown rate is a predetermined and substantially fixed percentage of the feed water rate.
Dependencies are inferred from the claim text.