Friday, June 15, 2018

Pneumatic Damper Drives Superior to Electric Drives on Boiler Dampers

Pneumatic Damper drives
Pneumatic Damper Drives (Rotork)
In flue gas and combustion air applications, rapid response is critical for optimal efficiency, safety, and equipment longevity. Pneumatic vane damper drives don't have gears or motor windings that slow down response or introduce slop. In power plants boiler applications, Rotork Type K damper drives continue to provide a better solution for critical damper applications over electric drives.

Electric Drive
Old Electric Drive
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. Pneumatic damper drives are excellent alternatives to electric drives in these applications because of speed, accuracy, and reliability.

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. Pneumatic vane drives react to signal changes and produce movement instantaneously and repeatably.
Pneumatic drive
New Pneumatic Drive

Rotork Type K PM Series Pedestal-Mount Damper Drives have proven themselves time and time again as 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.

The data collected after years of maintenance-free operation, in thousands of successful installations world-wide, is compelling. Pneumatic drives are superior to electric drives on boiler dampers.

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

Thursday, May 31, 2018

Increased cycle count improves operational efficiency in slurry ore mining operations

slurry pipeline
Slurry pipeline.
Long distance slurry pipelines for moving mineral concentrates over various elevations and long distances is often more economical than trucking or rail due to topography constraints and environmental concerns. To capitalize on these investments, the pipe sizes are maximized. Therefore, large-bore dependable valves are vital to the success of the slurry pipelines.

Three months after the main choke and choke loop press letdown stations were commissioned at a large copper-gold-molybdenum mining operation, ongoing repairs were required for all eight competitor valves. Valves in this position were expected to perform for at least 180 cycles without repair. These failures and leakage problems were caused by the valves’ integral seat design, which form a gap between the ball and seat allowing particles to enter the sealing area in the reverse pressure. This problem cost this customer an average of $800,000 to $1M per year in maintenance repairs.

MOGAS valve
After one year the
MOGAS valve performed 818
successful cycles—over four times the cycle
count required in this application.
Even with MOGAS’ 40-year history of successfully engineering large valves for the slurry transport market, MOGAS proposed to lease a test valve to be placed alongside a series of competitor valves.
In January 2013, a 36-inch, ASME 300 Class model CST-1 valve was installed in the first loop of the control station. In this model’s proven bi-directional seat design, the seat maintains 100% contact with the ball in both normal and reverse pressures. This prevents build-up behind the downstream seat and ensures evacuation of solids around upstream seat during cycling.

Under the same process conditions,
the competitor’s valve underperformed and
required frequent maintenance due to erosion.
One year later during decommission, the MOGAS valve was inspected. It had performed 818 cycles; far more than the 180 cycle count required in this application. The MOGAS valve was then removed and installed outside the loop, in the main choke station replacing the competitor valve, where it further performed 215 cycles for the next two years.

After three years of continuous operation, the MOGAS valve had successfully performed 1033 cycles. On inspection, the ball and seat were in good repair, so only the gasket and packing box were replaced and the valve was put back in to service.

Advantages to installing a MOGAS valve:
  • No downtime due to increased cycle time and continuous operation 
  • No repair or maintenance of ball and seat
  • Increased cycle count and greater revenue
For more information, contact CTi Controltech by calling 925-208-4250 or visit

Reprinted with permission from MOGAS.

Wednesday, May 23, 2018

Welcome to CTi Controltech

Since 1976 CTi Controltech has represented the leading process control and combustion manufacturers.  These products, together with our engineering capabilities, give CTi customers high quality solutions to the most difficult industrial applications.

CTi is focused on the top quality manufacturers in process control, valves, instrumentation, and combustion. Over the past three decades CTi has continually added and upgraded the quality of companies it represents.

Our staff of engineers and technicians is well versed with all our products and are ready to help you with your most demanding applications.

Wednesday, May 9, 2018

Rupture Disc Assemblies Designed to Protect Tanks Against Implosion or Overpressure Conditions

Continental Disc Corporation's CAL-VAC® and POS-A-SET® Rupture Disc Assemblies are highly accurate, double acting pressure relief devices designed to protect processing and storage tanks against implosion or overpressure conditions that can occur in:
  • Positive Pressure - overfill, external fire, steam regulator failure 
  • Vacuum Relief  - liquid pump out, insufficient flow through sanitary vent filer, flash vacuum due to CIP cool rinse, primary vent malfunctions, blanket gas or air regulator failure
Both designs relieve pressure settings starting as low as 1 InWC (inches water column) differential. The difference in the CAL-VAC Rupture Disc and POS-A-SET Rupture Disc is the orientation of the components to meet the relieving requirements. The CAL-VAC Rupture Disc relieves ultra low pressure in the vacuum (negative) pressure direction, while the POS-A-SET Rupture Disc relieves ultra low pressure in the positive pressure direction.

Wednesday, March 28, 2018

Fluid Processing - Plug Valves

plug valve cutaway view
Plug valve cutaway view
Image courtesy Flowserve - Durco
Fluid process control operations commonly employ pumps, piping, tanks and valves as the means of transporting, containing and controlling the fluid movement through a system.

Valves, of which there are many types, provide control over the flow rate, direction and routing of fluids in a processing operation. Flow can be started, stopped or modulated between zero and full rate using a properly sized and configured valve. Some valves enable media flow to be diverted to a selection of outlets, in lieu of a single inlet and outlet pair. Specialized valves regulate inlet or outlet pressure, or prevent fluid flow from going in an undesirable direction. All of these capabilities are packaged into differing valve product offerings that present a very large selection array to a process designer or engineer.

Industrial flow control valve types are generally classified according to the structure or arrangement contained within the valve body that provides obstruction to fluid flow. Some of the common types are ball, butterfly, gate, globe, and plug. Surely, there are more valve types, and this article is not intended to list them all. Some of our previous blogs have discussed selection considerations for gate, ball and butterfly valves. This article will focus on one of the oldest valve types, the plug valve.

Plug valves, like ball and butterfly valves, span from fully open to fully closed positions with a shaft rotation of 90 degrees. The “plug” in a plug valve is installed in the flow path within the valve body and rotated by means of a stem or shaft extending to the exterior of the body. Plugs are often tapered toward the bottom and are fitted to a seating surface in the valve body cavity that prevents fluid from bypassing the plug. An opening through the plug, the port, can be shaped to provide particular flow characteristics. There are numerous variants of the basic plug valve which may make it suitable for particular applications. One common variant is the lined or sleeved plug valve, with an insert or interior lining of material that creates an isolating barrier between the valve body and the media. This allows use of less expensive materials for the body construction that may be otherwise subject to corrosion by exposure to aggressive media.

Plug valves can be selected for a number of attributes.
  • 90 degree rotation from open to closed provides fast operation.
  • With proper configuration, can be well suited for frequent operation.
  • Availability of corrosion resistant liner may provide comparative cost savings because valve body can be constructed of less expensive material.
  • Design is simple and employs a low parts count.
  • Valve can be serviced in place.
  • Generally, low resistance to flow when fully open.
  • Reliable leak-tight service due to tapered plug wedging action, replaceable sleeve, and injection of lubricant in some variants.
Potential issues of concern for plug valve application include a short list of items.
  • Higher friction in the plug closure mechanism may require comparatively higher operating torque than other valve types.
  • Without a specially designed plug, generally not well suited for throttling applications.
  • Rapid shutoff delivered by plug design may not be suitable for some applications where hammering may occur.
Share your fluid control application challenges with a valve and automation specialist. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

Wednesday, March 21, 2018

Master-Martyr Valve Arrangements

electric industrial valve actuator with manual wheel
Electric actuator for industrial valves.
Image courtesy Rotork
Some industrial fluid flow applications are best served with what is known as a master-martyr valve set. Let's look at this arrangement and how it is used.

Valves are used to regulate flow. They are also applied to isolate portions of a fluid system by providing positive leak free shutoff. A master-martyr valve set utilizes two valves, with the performance of each targeted at differing performance goals. By coordinating the operation of the two valves, operational benefits accrue.

The master valve serves as the isolating valve. It will be located upstream of the martyr valve. The master valve provides fully open or fully closed operation and is commonly selected to accommodate the most severe operating condition anticipated in the system. Usually, this valve is normally open and is designed to contribute little to no pressure drop to the fluid flow. A good example is a full port metal seated ball valve. It offers very low pressure drop, substantial resistance to system pressure or heat, and can be driven from fully open to closed positions quickly.

The martyr valve provides flow regulation or throttling and is not intended to be the positive means of shutoff for the fluid flow. This valve will experience a range of pressure drop, possibly some flashing, or other conditions that, along with the frequent repositioning applied to the valve, will serve to produce wear and tear on the mechanism. Generally, the martyr valve is expected to wear out from normal operation and need servicing or replacement. The master valve, located upstream, serves as a point of isolation that allows the martyr valve to be easily serviced.

The overall goal is to operate the master valve as little as possible and expose it to the lowest possible pressure drop. Generally, this will call for the master valve to be opened first and closed last.

There are numerous potential applications for this valve arrangement. Smart actuators can function within the control system by delivering information about valve position and service level, as well as responding accurately to system commands. Share your fluid flow control challenges and applications with valve automation specialists. Leverage and effective solution by combining your own knowledge and experience with their product application expertise.

Tuesday, March 13, 2018

Patented Ballcheck Valve Eliminates Potential Commissioning Error

When using a ballcheck valve and commissioning a gauge assembly on a vessel containing liquid, a common mistake is to open the valve too quickly and engage the ball check. This will result in a false reading on the gauge. The 360 Series valve, from Jerguson, makes it impossible to get a false level reading during commissioning. The short video shows how the patented feature of the 360 simplifies commissioning by avoiding errors.
  • Eliminate false level readings during commissioning
  • Clean-out port enables internal inspection
  • Handle clearly indicates open or closed position of valve
  • Certifications for common applications
  • Lock-out / tag-out capability is standard
More information on this and related level gauge products is available from product specialists. Share your challenges with application experts and develop an effective solution by leveraging your own knowledge and experience with their product application expertise.