The purpose of boiler control is to achieve safe operation, reliability and optimised performance with respect to load change response, fuel cost and emissions.
In most control applications, repeatability or measurement is more important than absolute accuracy. Accuracy can be adjusted for software, but erratic readings cannot.
Drum level is critical for safety and reliability. Inaccurate drum level control can result in safety issue and equipment damage. High levels can cause water carryover that lowers heat transfer efficiency and possibly damages downstream equipment such as steam turbines.
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