To meet strict clean air regulations, most plants rely on low-NOx (nitrous oxide) burners in their boilers. The burners mainly rely on accurate control of the combustion air to reach the required NOx reduction. Many plants are considering advanced control option to improve the control of combustion air. However, precise position control of multiple dampers is needed in order to be successful,

To get the best damper control, engineers are currently replacing existing windbox dampers with electric servo actuators from Exlar (www.exlar.com). Each actuator, when supplied with the company’s all-digital SV positioners, will immediately respond to command signal changes within 5 mSec. The response speed combined with the all-electric actuator’s dynamic capability delivers greater repeatability and accuracy compared with pneumatic or induction motor actuators.

The patented linear actuator from Exlar is based on a unique design especially made for integrating an effective and robust threaded roller mechanism into the interior of a high performance, high power density brushless servo motor. If combined with an exact position feedback mechanism, the outcome is an extremely compact all-electric actuator, which delivers superior performance for damper control applications.

Exlar’s electric actuators have the roller screw’s design for transmitting forces. Moreover, Exlar’s high performance brushless servo motor yields control and speed that are unachievable by conventional motors.

The digital SV Series Positioners are specifically designed for use with rotary and linear actuators from Exlar for controlling dampers and valves in process control applications. The positioning of the damper along with the SV Series can be proportionally controlled in response to an analog input signal that allows simple control by PLC or DCS systems.

Additional characteristics include 3″ to 18″ stroke lengths, 2″, 3″, 4″, 5″, and 7″ frame sizes, up to 40″ per second linear speeds, up to 12,000 pounds max thrust capability, and rear clevis, front flange, double side, trunnion, side, or extended tie rods mounting options.