Thursday, September 21, 2017

Dampers and Louvers Used in Power Plants, Refineries, Boilers, and Furnaces

pneumatic damper drives, damper positioners
Several sizes of pneumatic damper drives
Image courtesy Rosemount Analytical - Emerson
A damper (also known as a louver) is a multi-element flow control device generally used to throttle large flows of air at low pressure. Dampers find common application in furnace and boiler draft control, and in HVAC systems. Common damper designs include parallel and radial configurations of the vanes.

Parallel-vane dampers resemble a Venetian blind, with multiple parallel rectangular vanes synchronously rotated to throttle flow through a rectangular opening. The rectangular shape of the assembly facilitates installation in rectangular duct. The vanes are mechanically linked so they function as one. A manual drive can be used to set the vane position. More commonly, an automated drive positions the vanes in response to a control signal.

Radial-vane dampers use multiple vanes arranged like petals of a flower to throttle flow through a circular opening or duct. Levers and linkages on the periphery of the tube synchronize the motion of the multiple vanes so they rotate at the same angle. Mechanical linkage to an external drive point enables position control similar to that of rectangular dampers.

Automated dampers can be positioned by a number of actuation means. A common design employs a double action pneumatic cylinder, along with integrated pilot valve and controls, to position the damper vanes. A example of such a device is pictured above and detailed in the document provided below.

Used in critical applications commonly found in power plants, refineries, boilers, and furnaces, these damper and drive combinations are coupled with combustion analysis instruments to provide precise combustion gas management and increased boiler efficiency,  with lower fuel consumption, reduced emissions, and reduce maintenance cost.

Share your combustion control and large air flow control challenges with an application specialist. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

Parts of this post are reprinted from Lessons In Industrial Instrumentation by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.