PROJECT: Steam Drum Level Control Stability

This major utility steam boiler was a Combustion Engineering (CE) forced water circulating balance draft boiler rated at 2,600,000 lbs/hr at a boiler drum operation pressure of 2,525 psig. The generating unit was capable of 350 MW. The boiler, and to a somewhat lesser degree its sister unit, both had a long history of challenges attempting to maintain stable drum water level. At the time this project began, the most problematic unit's drum level was so unstable the site was unable to place the unit in service.

The engineering services provided conducted a thorough evaluation of every process, instrumentation, and control component related to maintaining drum level. After submitting formal recommendations, the site approved all aspects of the recommended work scope. Management services were also provided to coordinate all instrumentation and mechanical upgrades. Since this problem had been getting progressively worse over the years, the site had tweaked many different parameters on most of the instrumentation and control system resulting in compounding the problem.

The newly corrected and upgraded drum level control system was placed in service with a dramatic improvement in drum level control that hadn't be observed at this site in 5 to 10 years; obviously allowing the operators to once again have this unit back in service.