20 Westinghouse Model 1500 GPC (General Purpose Controller) Micro's

EQUIPMENT


Westinghouse Model 1500 GPC (General Purpose Controller) Micro's


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 when I was called to resolve this problem, the most problematic unit's drum level was so unstable the site was unable to place the unit in service.

I was the principal investigative engineer and conducted a thorough evaluation of every process, instrumentation, and control component related to maintaining drum level. After submitting my formal recommendations, the site approved all aspects of recommended work scope and I oversaw or directly participated in all changes to this sytem. 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.

RESULTS


• Reverse engineered the complete feedwater flow/drum level control system, found and corrected all design flaws, tuning constants, and characterizations, and commissioned in the old Westinghouse Model 1500 GPC (General Purpose Controller) micro's.

• Upgraded the functional control logic for drum level control to a more standard design including installing the correct drum pressure compensation for converting differential pressure level instrument to drum level.

• Conducted final construction inspection, all control system loop checks, systems startup testing, and final commissioning to full operating status for the upgraded boiler drum level indication and control system.