Control system for a boiler and method therefor
AssigneeMeasurex Corporation
InventorsLaxmi K. Rastogi, Arthur D. Allen, John Y. H. Tsing
Life of this patent
Estimating the term…
Abstract
A method and system for controlling the combustion of, for example, coal or bark in a stoker boiler or black, liquor in a recovery boiler to provide operation at maximum efficiency. Control loops are provided for primary or undergrate air and secondary or overfire air. The undergrate air control loop is adjusted as a function of carbon dioxide or steam/fuel ratio, and the overfire air control loop is adjusted as a function of carbon monoxide. In addition to carbon monoxide, combustibles and opacity may be used. Air redistribution is also used to minimize combustibles or CO or opacity.
Claims10
A control system for a boiler producing steam having a fire bed of fuel where air is admitted under or at the fire bed (undergrate air) to accomplish the preliminary burning of fuel in said fire bed and air is admitted over the fire bed (overfire air) for completing combustion, said system comprising:
- means associated with the exhaust stack of said boiler for sensing carbon dioxide and carbon monoxide in the flue gas;
- means for controlling the amount of said undergrate air admitted into said boiler as a function of said carbon dioxide or steam/fuel ratio;
- means for controlling the amount of said overfire air admitted into said boiler as a function of said carbon monoxide.
A method of control of a boiler producing steam having a fire bed of fuel where air is admitted under or at the fire bed (undergrate air) to accomplish the preliminary burning of fuel in said fire bed and air is admitted over the fire bed (overfire air) for completing combustion, said method comprising the following steps:
- sensing carbon dioxide and carbon monoxide in the flue gas;
- controlling the amount of said undergrate air admitted into said boiler as a function of said carbon dioxide or steam/fuel ratio;
- and controlling the amount of said overfire air admitted into said boiler as a function of said carbon monoxide.
Dependencies are inferred from the claim text.