Today’s industrial climate is characterized by ever increasing fuel costs, emission regulations, global competition, and technological advances – all of which necessitate boiler control improvements. Whether producing process steam or plant power, boilers need to maintain optimal combustion and feedwater control under a variety of conditions. In response, industrial plants are continually investing in control systems and instrumentation to meet regulations, reduce costs, and avoid costly outages.
At the heart of boiler control and efficiency is actuation. Often ignored, control valve and damper actuators play a key role in the overall performance of a boiler. But actuator performance is commonly measured in terms of reliability only and in many cases, actuator problems tend to be addressed only after a serious or complete failure occurs. The rest of the time, poor control goes undetected, or is simply tolerated, while more visible problems receive attention.
Control valve and modulating damper actuators are a leading source of boiler control problems. Pneumatic actuators are highly susceptible to stick/slip response (Figure 1), excessive dead time, inconsistent performance with changing conditions, and degradation over time. Similarly, typical electric actuators are poorly suited for active boiler control since most are limited by motor duty cycles (Figure 2), provide less accurate positioning capabilities, and are less reliable – especially in harsh operating conditions. Whether a boiler is large or small, subject to severe load swings or base-loaded, Beck electric actuators are designed to provide the best possible control regardless of external factors.
How do Beck electric actuators improve boiler control and eliminate the inherent problems of pneumatic actuators and typical electric actuators?
- 100% Continuous Duty Motor (Figure 2)
- A Beck provides continuous modulating control and does not suffer from duty cycle limitations like typical electric actuators.
- Instantaneous Response
- A Beck responds to a modulating controller demand signal instantaneously, regardless of changing loads and conditions. There is no stick/slip response like pneumatic actuators, thus eliminating dead time and position overshoot.
- Maintenance Free
- A Beck provides consistent control over time with virtually no maintenance requirements.
- Repeatable & Precise Control (Figure 3)
- A Beck tracks the controller demand signal closely under closed-loop conditions, with resolution unmatched by pneumatic and typical actuators. This eliminates limit cycling and ensures tight, stable process control.
- Reliable Performance
- Weather, dust, dirt, and temperature [-40°-185°F] conditions do not affect performance.
These benefits not only improve process control, but in turn help optimize boiler efficiency and reduce emmissions.