Kinetrol Vane Actuator Outperforms Rack and Pinion on Power Plant Filter-Demineralizer System

Kinetrol Vane Actuator on Power Plant
Filter-Demineralizer System

An important component of combined cycle power plant design and operation is condensate polishing, commonly referred to as "CP". CP is a process that purifies condensate. High purity condensate maximizes uptime in power plants by maintaining stable condensate chemistry and reducing corrosion transport. Power plants install specialized filter-demineralizer systems which remove both suspended solids and ionic contaminants to maintain optimal condensate  chemistry.

At one midwest power utility company, a valve controlling the flow of water (210 psi and 140 deg. F) that feeds the demineralizer was causing concern. The valve's accompanying rack and pinion actuator was creating a maintenance problem. While this isn't a high cycle application, the system must be 100% reliable, and the old actuator's performance was unreliable. The solution was to install a Kinetrol vane actuator. A new automated valve was installed 6 years ago (2012) and the Kinetrol actuator has operated flawlessly since then.

Cement Hopper Valve Actuator Requires Kinetrol's Accuracy, Dependability and Toughness

Location of the actuator and valve at bottom of hopper.

A midwestern cement plant had a hopper loading system that was being manually controlled. A human operator, using a long pole attached to a valve arm on a hopper, dispensed the flow of cement. The silo is divided internally into 4 sections. Each section has its own 12" butterfly valve which allows product to fall into a single hopper above a weighing scale. At the bottom of the hopper, and above the truck loading spout, the butterfly valve throttles the product into cement trucks.

No only did this approach require a human operator (with associated costs and safety precautions) to be present, the manual system didn't provide the degree of control the company needed. Careful control of the cement into the truck is important because uncontrolled flow, or too rapid a flow, will overwhelm the dust collection system and allow fugitive emissions (dust) to escape to the atmosphere. A serious regulatory and safety issue.

Kinetrol actuators and positioners perform in dirt and dust.

Together, the local Kinetrol Distributor sales rep and customer came up with a new system utilizing a Kinetrol vane actuator and an EL electropneumatic positioner. The new design accurately modulates the cement flow through the 12" valve. This approach gives the customer much closer flow control and eliminates the need to a human operator. It also allows for the terminal to be remotely operated from more than 4 miles away, all with reliable and repeatable results.

For more information, contact Kinetrol USA by visiting https://kinetrolusa.com or by calling 972-447-9443.

Power Plant Bearing Cooling Water Temperature Control

A midwest power plant was using a diaphragm control valve to control water temperature for their bearing cooling system. The closed-loop bearing cooling system uses the modulating valve to control water temperature between 50 and 170 degrees F. at 170 PSIG. The diaphragm valve was not able to provide the required signal response for tight control.

The local Kinetrol Distributor specified a high performance butterfly valve (HPBV) with Kinetrol spring return actuator and third-party positioner. The new valve and actuator package provided  reliable and accurate controllability with zero hysteresis. It has operated continually for 3 years without maintenance.

Bearing Cooling Water Temperature Control Valve

Kinetrol Actuators on Power Plant Descaling Water System

Kinetrol actuator on
descale water system.

Overtime, heat exchanger tubes in power plant boilers build up mineral deposits that prevent proper heat transfer. The poorer the heat transfer, the higher the boiler tube exposure temperature. The higher the exposure temperature, the shorter the life of the boiler tubes. To remedy this, a chemical and mechanical process called descaling is used. Descaling removes these mineral deposits and restores proper heat transfer.

Wider view.

This Kinetrol actuator application is located on the descale water system at a power plant in the Midwestern United States.  Knifegate valves with pneumatic cylinder actuators were installed on the system and were failing. The knifegate valve packing material leaked and created a maintenance nightmare. The customer needed a longer term, lower maintenance solution.

The local Kinetrol Distributor recommended switching to a high performance butterfly valve (HPBV) and Kinetrol double acting actuator as the replacement. These actuators and valves are installed in a very dirty area (see picture), and during power generation, are exposed to high heat and are cycled every 30 seconds. The first installation has been in place for 20 months and operating without problem. Now, as each knifegate comes up for maintenance, they are being replaced with the Kinetrol operated butterfly valve.

For more information, contact Kinetrol USA by visiting https://kinetrolusa.com or calling 972-447-9443.

Kinetrol Blueline Food-Grade Rotary Vane Actuators

Kinetrol Blueline Food Grade Valve Actuator from Kinetrol USA

Pneumatic Valve and Damper Actuators: A Design Comparison

Industrial valves, dampers and louvers are operated either electrically or pneumatically. This post compares the three major categories of  pneumatic valve actuators, namely:

1. Rotary vane
2. Scotch-yoke
3. Rack & pinion

All three categories provide the same basic function - converting air pressure to rotational movement intended to open, close, or position a quarter-turn valve (ball, plug, butterfly), louver or damper.

All three can be configured in either direct acting or spring return versions. Direct acting actuators use the air supply to move the actuator in both directions (open and close). Spring return actuators, as the name implies, uses springs to move the actuator back to its "resting" state. Converting from direct acting to spring return is done through simple modifications, typically just adding an external spring module, or removing the end caps from rack and pinion actuators and installing several coil springs.

Rotary Vane Actuator

Rotary Vane Actuators

Vane actuators generally provide the most space savings when comparing size-to-torque with rack and pinion and scotch yoke. They have an outstanding reputation for long life because then contain only one moving part, as opposed to rack and pinion and scotch yoke actuators that have many. They tend to withstand dirty and corrosive atmospheres better than rack and pinion and scotch yoke actuators. Vane actuators also use externally mounted, helically wound "clock springs" for their spring return mechanism.

Scotch Yoke

Scotch-yoke actuators use a pneumatic piston mechanism to transfer movement to a linear push rod, that in turn engages a pivoting lever arm to provide rotation. They come in a wide variety of sizes, but are very often used on larger valves because they are capable of producing very high torque output. Spring return units have a large return spring module mounted on the opposite end of the piston mechanism working directly against the pressurized cylinder.

Rack and Pinion

A rack & pinion pneumatic actuator uses opposing pistons with integral gears to engage a pinion gear shaft to produce rotation. Rack & pinion actuators (sometimes referred to as a lunch box because of their shape) tend to be more compact than scotch yoke, have standardized mounting patterns, and produce output torques suitable for small to medium sized valves. They almost always include standard bolting and coupling patterns to directly attach a valve, solenoid, limit switch or positioner. Rack and pinion actuators use several smaller coil springs mounted internally and provide the torque to return the valve to its starting position.

The practical difference between these three types of pneumatic actuators comes down to size, power, torque curve and ease of adding peripherals. For the best selection of valve actuator for any quarter turn valve application, you should seek the advice of a qualified valve automation specialist. By doing so your valve actuation package will be optimized for safety, longevity, and performance.

Scotch yoke mechanism image courtesy of Wikipedia.
Rack and pinion mechanism image courtesy of Wikipedia.

Updated Kinetrol Rotary Actuator Catalog - March 2018

Here is the March 2018 edition of the Kinetrol Rotary Actuator Catalog. You may view it in the embedded viewer below, or download it from this link.

Kinetrol Rotary Actuator Catalog March 2018 from Kinetrol USA