The Virtues of the Pneumatic Vane Actuator Damper Drive

Pneumatic damper drives

Pneumatic damper drives significantly improve the reliability, precision, and efficiency of industrial boilers and furnaces. Accurate control of combustion air and flue gas provide many cost savings benefits to plant operators. A pneumatic damper drive’s precision and rapid response greatly improve fuel efficiency, reduce emissions, lower fuel consumption, and provide better boiler draft control.

Recent “Boiler MACT” (Boiler Maximum Achievable Control Technology) regulations require regular maintenance to optimize boiler performance. Air-to-fuel mixing and CO emissions are two areas where fine tuning and precise control yields dramatic improvement in burn efficiency. Old electric drives do not provide the precision, speed or torque needed for accurate control, so a retrofitting program that replaces electric drives with pneumatic units is an easy way to improve efficiency and gain better performance.

In the application outlined below, several dual-arm damper drives, using Kinetrol Model 18 actuators, were specified to replace aging Bailey electric damper drives in a power plant in the southwest USA. These specific drives are used to control the desuperheater and reheater temperature at a gas fired plant. Not only was there a need for optimized performance for better fuel consumption and lower emissions, but the customer was also very concerned about reliability. The plant needed to know the new Kinetrol-based damper drives were immediately available, and ready for drop-in replacement as the Bailey drives failed. This was easily managed by designing pedestals and frames that matched the bolting patterns and envelope size of the existing Bailey units. The Kinetrol drives were designed to match the legacy footprint exactly, have the drive shaft and drive lever in the exact position, and provide a drive shaft and lever with the same dimensions as the Bailey drive.

The result is a high duty cycle, highly precise, long-life, fast acting, responsive, easily maintained, and easily automated damper drive.

The Principles of Rotary Actuators

Variation of the rotary actuator.
(Kinetrol pneumatic vane actuator.)

A rotary actuator is an output device for a fluid power system that delivers an oscillating motion over a limited range in less than one full revolution of the circle.

A true rotary actuator produces work by direct action of fluid pressure against internal vanes. Work is defined as a force applied over a distance. Rotary actuators produce a special type of rotational work called torque.

Torque occurs when a force acts on a radius. Since rotary actuators operate at low speed with high torque, torque output rather than the horsepower is used for the rating and identification purposes. Speed is a secondary consideration when choosing a rotary actuator for a particular application.

The typical units of measurement for torque are foot pounds (lb·ft). For example, if a rotary actuator with an arm length or radius of two feet were used to lift the two hundred-pound weight, then the resultant torque required to accomplish the work would be 400 lb·ft.

Understanding the relationship between the output torque required and the physical set up a fluid system enables designers to determine the appropriate rotary actuator for each unique application.

The following video does an excellent job of illustrating the mechanics and the physics behind rotary actuators.

Water Recycling Application at Iron Ore Mine

Mining corporations need water - a lot of water - to make bare rock give up its valuable minerals.

Water is used for the extraction of minerals that may be in the form of solids, such as coal, iron, sand, and gravel. The category includes quarrying, and milling (crushing, screening, washing, and flotation of mined materials).

Not only is water used to expose the mineral, it must be carefully managed to prevent the release of contaminated water back into the environment.

There are multiple processes involving the management of water that require piping, valves and automation for water management.

• The reuse of water used to extract the minerals from the other solids.
• Managing surface water from rain, snow, and streams.
• Capturing and recycling water from the mine site.
• Storing water in evaporation ponds.

At a large Midwest iron ore mining facility, a Kinetrol Distributor was contacted to look at ways to lower the overall consumption of water in the main water treatment plant.

The Distributor designed and provided this characterized butterfly control valve, with a Kinetrol actuator, pneumatic positioner, and cone indicator.  The valve is used to recycle processed water back into the plant for reuse in the extraction process. The valve and actuator experiences a very high cycle rate (400 cycles per day).

Intercepting and diverting surface water

• Intercepting and diverting surface water (rain and snowmelt runoff, streams, and creeks) from entering the mine site by building upstream dams to reduce the potential for water contamination from exposed ore and waste rock
• Recycling water used for processing ore in order to reduce the volume of water requiring treatment
• Capturing drainage water from precipitation at the mine site through the use of liners and pipes and directing the water to tailings dams in order to prevent potentially contaminated water from entering groundwater or flowing off site
• Allowing the water to evaporate in ponds to reduce the volume of contaminated water; in dry regions, enough water may be evaporated that no water needs to be discharged, resulting in the containment of contaminates at the mine site
• Installing liners and covers on waste rock and ore piles to reduce the potential for contact with precipitation and contamination of groundwater

- See more at: http://www.miningfacts.org/Environment/How-is-water-managed-and-treated-in-mining/#sthash.0qMpVdHr.dpuf

Segment Ball Control Valve with Vane Actuator, Pneumatic Positioner, and I/P Transmitter

Actuator and Positioner

Ball, plug and butterfly valves all belong to a class of valves commonly referred to as "quarter-turn" valves. This refers the 90 deg (angular) rotation required to go from full closed, to full open position.

In most cases standard ball, plug, or butterfly valves are not the best choice as control valves (where the process media has to be modulated or throttled). Standard ball, plug and butterfly valves usually introduce very non-linear, dynamic flow coefficients. Furthermore, they can introduce undesirable turbulence to your piping system.

As a means to linearize flow coefficients and reduce turbulent flow, the machining, or characterization, of the valve disk is done so that the machined shape allows for more optimized flow.

For ball valves in particular, machining the ball's flow port with a "V", or even by machining the ball more radically, can deliver excellent flow curves. A term for a more radically machined ball is the "segment ball" (sometimes called "segmented").  In the following video you can see how a Kinetrol pneumatic actuator, postioner, and I/P transmitter team up with a segment ball valve foe an excellent control valve.

Very High Cycle, Coal Power Plant Butterfly Valve Application

One moving part. Simply the best.

A coal fired power plant was using old Powell gate valves with dual air cylinders and volume tanks. Because of high cycle rate (the valve cycles open/closed every 30 seconds), the Powell gate valves were breaking down constantly - leaking at first, then failing. Downtime for repair was costing a fortune.

Kinetrol Model 12

A local Kinetrol Distributor was called in to recommend a better solution. After discussing the capabilities of Kinetrol, the power plant decided to replace the gate valves with 6" high performance butterfly valves actuated with Kinetrol size 12 actuators, spring returns and limit switch packages. 

The result was a robust valve/actuator package that could handle the 120 cycles per hour required - truly a difficult application. As of two years in operation, both valve and actuator have been running reliably much to the delight of the power plant maintenance crew. 

High cycle coal fired power plant Kinetrol / HPBV application.

Innovative Approach to Add Manual Failsafe Handles for Large Quarter-Turn Valves

Kinetrol manual failsafe unit

Let's assume you have an application where it's critical that a large, pneumatically actuated valve cannot be left unattended in the wrong position (opened or closed). Or maybe your application requires the use of a manual operator with a fire-safe fusible link. The problem though, is the valve you want to control has torque requirements much greater than the output of any manual failsafe unit can provide. 

Here's an innovate and effective way to incorporate a manual failsafe unit on large size ball, butterfly, or plug valves. 

Retrofit your large valve with a 3-way "L" port ball valve and a manual failsafe spring handle on the large valve actuator's inlet air supply port. 

This allows the opening of the valve with the manual failsafe handle. When the handle is released, the valve shuts automatically by venting the air to atmosphere, and allowing the springs in the actuator to close the valve. 

Size limitations on the valves are no longer an issue, and this will work on anyone's pneumatic spring return actuator (spring return required, will not work on double acting actuators). 

Manual Override for Larger Valves

Limit Switches for Your Rotary Vane Actuator in Hazardous Areas

This Explosion Proof Limit Switch Box offers a wide range of signaling options in a compact corrosion resistant aluminum alloy housing available for close - mounting onto Kinetrol actuators or discrete mounting via a Kinetrol 05 square or industry standard VDI/VDE interface onto any make of rotary actuator. Easy to wire and set up with true industrial robustness.

Internally fitted options include AS interface digital communication and a 4-20mA, 2-wire, modulating angle retransmit circuit. The range of switches and terminal arrangements includes 2 or 4 switches and extra connections - allowing single point termination of wiring for limit switches and solenoid valves. This product is available to mount on Kinetrol models 03 - 30.

Kinetrol Explosion Proof Limit Switch from Kinetrol USA