Pneumatic Vane Damper Drives for Boiler Flue Gas and Combustion Air: A Superior Alternative to Electric

Obsolete ID fan inlet
damper drive.

Pneumatic damper drives are excellent alternatives to electric drives because of speed, accuracy, and reliability. Pneumatic vane damper drives don't have gears or motor windings that slow down response or introduce slop. Pneumatic vane drives react to signal changes and produce movement instantaneously and repeatably.

In flue gas and combustion air applications, rapid response is critical for optimal efficiency, safety, and equipment longevity. In power plants, Rotork Type K damper drives provide a better solution for critical damper applications over electric drives.

Type K damper drive
'drop-in-place' replacement.

Balanced-draft power generation boilers can experience very serious equipment failures if low pressure conditions exist inside the combustion chamber. Transients in boiler pressure can cause combustion complications leading to irregular heating of steam tubes, and in extreme situations, negative boiler pressure can collapse boiler walls and buckstays. There is a possibility for catastrophic failures (ruined boiler tubes, destroyed  refractory, boiler structural damage) leading to long shutdowns, lost production, and expensive re-construction.

Understanding the catastrophic possibilites, it is extremely important to provide consistent internal operating pressure environment for efficient and manageable combustion. ID (induced draft) fans on combustion boilers play a critical role in maintaining reliable boiler pressure. In turn, the ID fan inlet damper control system that regulates fan induced airflow and pressure need to be accurate, responsive, and reliable to assist in keeping boiler combustion chamber pressure fluctuations in check.

Rotork Type K 'PM Series' Pedestal-Mount TK-6 Damper Drives have proven themselves time and time again to be the best choice for these applications. Pneumatic vane drives deliver high torque at tested speeds of less than 3 seconds for a full 90-degree stroke. They offer drop-in-place retrofit to the existing damper drive footprint, plus smart positioner technology. The Type K Drives perform quickly and smoothly at full boiler pressure and damper load, and as required, fail to the fully closed position.

For use on boiler dampers, the years of maintenance-free operation, in thousands of successful installations world-wide, the data clearly demonstrates pneumatic drive's superiority over electric drives.

Finally, always discuss your damper drive application with an experienced applications engineer for best selection, optimal performance, and maximum safety.

Rotary and Linear Damper Drives for Control of Combustion Air and Flue Gas

Electric Damper Drive (Rotork)

Combustion air and flue gas damper drives fill a critical role requiring safety, accuracy and reliability above all else. It is critical to deploy the best drive technology to maximize combustion efficiency, minimize emissions and reduce installation costs.

Damper Operator (Drives) Types :

Damper drives can be one of three types: pneumatic, electric, or electro-hydraulic, as described below.

• Pneumatic. These damper operators are used whenever controls rely primarily on compressed air (pneumatic) for moving operators.
• Electric. These damper operators are used whenever controls rely primarily electricity as the power source.
• Electro-hydraulic. These damper operators are the same as the electric type described above, but also have a hydraulic system to position the damper.

Pneumatic Damper Drive
(Rotork Type K)

A very important part of damper design is determination of damper torque and sizing and selection of damper actuator for the maximum torque. Actuator torque should be selected to provide the maximum torque required to operate the damper as well as to provide margin and allow for degradation over the life of the damper. Actuators should be evaluated for damper blade movement in both directions, at the beginning of blade movement, and while stroking blades through the full cycle of movement.

The Goal for Selecting the Best Drive Technology:

Reduced emissions, lower fuel consumption and improved boiler draft control.

Ways to achieve this goal:

Installed Damper Drive

• High speed continuous modulation of ID/FD fan and inlet guide vanes 
• Improved modulation and control of secondary air dampers 
• Improved automation and burner management 
• Quick response to plant demand 
• Improved reliability in high temperature environments 
• Precise damper and burner positioning 
• Simple commissioning and diagnostics 
• Low running costs, virtually maintenance free 
• Pneumatic, analog and bus network communications 

For more information, review the document below, or download it at this link on Power Specialties website.

Rotary and Linear Damper Drives for Control of Combustion Air and Flue Gas from Power Specialties, Inc.

K-TORK Actuators + Controls by Rotork

K-TORK pneumatic
actuators by Rotork

The K-TORK Range of high-performance ‘True Rotary’ vane actuators are used in critical applications commonly found in most process industries. Located in Dallas, Texas, USA, K-TORK products are supplied to USA customers in Kansas, Missouri, Nebraska and Iowa through it’s distributor Power Specialties, Inc.

K-TORK Actuators + Controls are versatile, modular and available in both double-acting and spring-return models. They are used to operate ball, butterfly or plug valves, and other 90-degree or less rotating mechanisms.

K-TORK Actuators + Controls represents the future of valve automation. The vane actuator is a ‘True Rotary’ actuator that does not require the conversion of a linear motion to a rotary motion. The result is a simple, highly accurate and reliable quarter-turn pneumatic actuator that is specified for the most demanding process flow control applications.

For more information about K-TORK contact Power Specialties online at http://www.powerspecialties.com or call (816) 353-6550.

Type K Vane Actuator Provides Long Term Solution for Tough Power Plant Application

Rotork K-TORK vane type valve actuators on
bottom ash spray valve control.

Rotork K-TORK vane type valve actuator has solved a difficult flow control application found in many coal-fired power plants – high-pressure bottom ash spray valve control.

High-pressure spray water is used to sluice bottom ash and pyrites from the boilers’ hopper bottoms and to carry the ash out of the plant. The valves used are typically ANSI Class 300 double-offset high-performance butterfly designs ranging in size from 3” to 12”, automated with double-acting actuators. They cycle from four to ten times per day and discharge to atmosphere, creating a very high pressure drop. The flow media is re-circulated ash water that is abrasive and flows at pressures between 400 and 500psi.

In many power plants around the world, K-TORK actuators have provided over 10 years of maintenance-free service whilst preserving the life of the valves and valve seats in these arduous duties.

Among the challenges, it is imperative that the valves close fully and with zero leakage in a high pressure drop state. If the valve disc moves even slightly from the seat, the abrasive, high-pressure water will “wire-draw” or cut the butterfly valve seat. Traditionally, rack-and-pinion or scotch-yoke actuators have been used in this application, but “slop” or hysteresis in the rotary-to-linear conversion allows for the pressure in the pipe to move the disc from the seat, often causing premature failure of the valve after a period of only three to twelve months.

The problem becomes more acute when multiple valves are leaking, lowering the available back-pressure at the header, which makes it difficult or impossible to move the ash from the boiler.

When assembled to the valve with a ‘No-Play’ coupling, the K-TORK actuator has zero lost motion, “slop” or hysteresis. The one-piece vane and drive shaft cannot be back-driven and will hold the disc of the valve firmly in place.

Additional challenges include the location of the valves on a manifold at the bottom of the boiler where space is critical and plant air can be poor quality. K-TORK provides the smallest torque-to-size ratio and the double-opposed lip seal design is forgiving to dirty or contaminated air.

Also, the low-friction performance of K-TORK provides a speed-controlled, smooth valve operation, eliminating the risk of water hammer created by the high pressure drop.

Finally, longer run time between shutdowns demands increased reliability from the equipment in these critical applications. In particular, as the number of plant maintenance personnel has decreased, actuators that reduce maintenance (seal replacement) time and work orders have a direct payback to the owner, especially when valve life can be significantly increased through improved actuator performance.

Easy Damper Drive Replacement on Steam Turbines

3 day damper drive
replacement and
turn-around.

Reprinted with permission from Rotork Type K

Two turbine intake radial vane dampers were equipped with pneumatic controllers which had become obsolete. The old actuators did not respond quickly and accurately to signals from the control system, resulting in potentially inefficient combustion and undesirable emissions. Replacing the actuators was necessary to increase efficiency, reduce maintenance and the associated costs that could result from unplanned shutdowns.

The equipment selected to upgrade the old actuators was Rotork Type K damper drives, which provide a direct ‘drop-in-place’ replacement that exactly matches the existing damper drive footprint and output shaft location. Duplication of the existing drive’s dimensions simplifies the installation, enabling the upgrade to be swiftly completed in a matter of hours.

Type K damper drives incorporate vane type actuators that offer high speed full stroke capabilities of less than 5 seconds, combined with accurate and responsive positioning. The rugged construction is designed to withstand the harsh environments associated with power stations and combustion plants.

Once the two Type K pedestal mounted damper drive units had been delivered, installation of both units was performed by engineers from Rotork Site Services within three days.

Days one and two were taken up with the removal of the old equipment and the installation of new, enabling commissioning, testing and hand-over to be completed during day three.

For more information on Rotork Type K Damper Drives, visit this link or call Power Specialties at (816) 353-6550.

Vane Actuator Damper Drives Assist in Boiler Emissions Compliance

Vane actuator style damper drive
(courtesy of Rotork Type K)

As environmental concerns increase and legislation continues to tighten standards for reduction in known air pollutants, emissions from industrial boilers faces continual scrutiny. The recent Boiler Maximum Achievable Control Technology (MACT) Rule is a prime example. MACT requires annual or semi-annual check-ups of the USA’s 14,000+ boilers and process heaters to assure compliance with emission standards.

Airflow is one of the most critical components of boiler control ensuring for safe, reliable, and efficient operation.  Poor airflow control can result in toxic gas production, inefficient burning, erratic cycling, and flame outs. More efficient combustion is key to lowering emissions, and the key to efficient combustion is optimizing the flow of combustion air and flue gas.

Dampers are used to control the quantity of air admitted to the furnace, and tighter boiler draft control significantly improves combustion. However, many of todays boilers employ old technologies, such as gear-laden, electric motor style damper drives that are not accurate or lack the required power to position the airflow dampers quickly or with repeatability.

Drop in pneumatic damper drive
(Type K)

Converting to pneumatic vane actuators is a proven method to provide high speed continuous modulation of ID (Induced draft) and FD (Forced Draft) fans, inlet guide vanes and secondary air dampers the accuracy and speed required for precise control. Replacing obsolete electric drives with fast acting pneumatic damper drives, driven by rotary vane actuators, offers significant improvements to burner management and cleaner performance.

The pneumatic vane actuator style damper drive is fabricated to deliver “drop-in-place” retrofit designs that precisely fits the application without any field engineering or additional fabrication. As part of the overall design strategy, existing connection rods, linkages and shaft accessories are be used without modification, resulting in quick change out and fast commissioning.

The performance of the vane actuator is key, providing 100% duty cycle, high torque outputs, and robust construction designed to handle hot, dirty and high-vibration environments. Vane actuators have long been known for their extreme long life and ability to withstand high cycle rates.

Tight control is provided by highly accurate, direct-mount pneumatic and electro-pneumatic positioners. A variety of optional network communication systems such as HART, Foundation Fieldbus, Profibus, and Modbus are also available.

Pneumatic vane actuator damper drives provide fast and accurate positioning, reduces overall operating air consumption, and saves cost by lowering fuel consumption. If you’re under pressure to improve boiler performance, and see improved burner management as part of the solution, upgrading your old gear-driven mechanical drives to drop-in vane actuators dampers drives will provide immediate improvements in efficiency and a substantial return on investment.

For more information on pneumatic damper drives, contact:
Power Specialties, Inc.
9118 E. 72nd Terrace
Raytown, MO 64133
Toll Free: (800) 432-6550
Phone: (816) 353-6550
Fax: (816) 353-1740

www.powerspecialties.com

Pneumatic Combustion Air and Flue Gas Damper Drives Provide Greater Efficiency

Stack Damper at Refinery
(courtesy of Rotork Type K)

Combustion air and flue gas damper drives fill a critical role requiring safety, accuracy and reliability above all else. Pneumatic type, rotary damper drives improve the efficiency and reliability of large and small boilers, furnaces and process heaters by maximizing combustion efficiency, minimizing emissions and reducing installation costs.

Rotary pneumatic drives deliver quality and power, but most importantly the provide precise control and speed to improve the BTU/Fuel ratio and increase the MW/Fuel ratio. This "better burn" results in reduced emissions, lower fuel consumption and improved boiler draft control. Specifically, these drives provide:

• High speed continuous modulation of ID/FD fan and inlet guide vanes
• Improved modulation and control of secondary air dampers
• Improved automation and burner management
• Quick response to plant demand
• Improved reliability in high temperature environments
• Precise damper and burner positioning
• Simple commissioning and diagnostics
• Low running costs, virtually maintenance free
• Pneumatic, analog and bus network communications

Pedestal mount damper drive
(courtesy of Rotork Type K)

The heart of the rotary pneumatic drive is the high performance rotary vane actuator. The totally enclosed design eliminates internal gears, levers and crank arms where hysteresis is created, leaving an output that has no “lost motion”, “slop” or “backlash”.  The result is the most accurate and repeatable pneumatic damper drive available to the industry.

Finally, these damper drives are designed as a "drop-in-place" solution that precisely fits into the application with no field modifications.  The concept focusses on providing the end-user with a high-performance drive that can be installed without any field engineering or modification using basic hand tools in a few hours. Existing connecting rods and linkages are reused without modification. Retrofit drives fit directly on the existing mounting pad using existing hardware.

Before retrofit

After retrofit

For more information about pneumatic combustion air and flue gas damper drives, contact:

Power Specialties, Inc.
9118 E. 72nd Terrace
Raytown, MO 64133
Toll Free: (800) 432-6550
Phone: (816) 353-6550
Fax: (816) 353-1740

www.powerspecialties.com

The Retirement of a Damper Drive Legend

Kansas City is famous for many things. We are the home of jazz, home of the best BBQ, home of the Negro League Baseball Museum and also home of the 1st damper drive ever built by Controls International (now Rotork Type K).

I would like to share the legend of Dick Scholtz as I know it. This story of how the Type-K concept was first conceived has been told many times by many people,

The story goes that Dick had sold several competitor's vane actuators to one of his very good customers. The same customer had been experiencing problems with his pneumatic damper drives and understood the merit of the vane design. Dick worked together on a plan to integrate the vane actuator into a damper drive, while the customer fabricated a stand to mount the actuator. The result was one outstanding, accurate, and long-life damper drive.

On a follow-up visit to the plant, Dick had a conversation with his customer who told Dick the plant would like to retrofit several additional damper drive applications, but he didn’t want to use Dick’s actuator! Of course, Dick was stunned and replied, “I thought that the actuators have been performing flawlessly” to which his customer responded, “They are!”

Dick shook his head, paused and replied, “Well then why in the world wouldn’t you want to use my actuator?”.

The customer quietly then explained, “Dick, listen closely, I don’t want to use your ACTUATOR, I want to use your DAMPER DRIVE”.

The light came on and the damper drive business at Controls International was born (later to become Rotork Type K Drives).

Dick Scholtz trained so many salesmen on so much more than damper drives. Dick taught us how to be better salesmen. Dick showed us the importance of attention to detail, surveying every last detail of a customer installation so that the replacement damper drive just dropped into place like magic. Dick’s magnetic personality (coupled with $50 of the best pastries available from St. Louis Bread Company) were a sure-fire win at every client. We all enjoyed tremendous growth in large part to Dick Scholtz. When talking with Dick on the phone, many times he would end the phone conversation with “Go get ‘em Tiger” and make you feel like a million bucks. His contribution and friendship will never be forgotten.

Tim Haas

President

Power Specialties