Flow Conditioners

If you’re planning to expand, upgrade, or retrofit your plant, chances are it will be hard to find a place for all that new or upgraded equipment. Many fluid handling devices require specific, space-intensive, piping practices to operate properly, and you may run out of room in trying to implement these inside plant buildings or even outdoors.

09/01/2006


If you’re planning to expand, upgrade, or retrofit your plant, chances are it will be hard to find a place for all that new or upgraded equipment. Many fluid handling devices require specific, space-intensive, piping practices to operate properly, and you may run out of room in trying to implement these inside plant buildings or even outdoors. Pumps, compressors, valves, flowmeters, blowers, burners, and other devices frequently require straight runs of pipe upstream and downstream to stabilize material process flow for effective performance. Installing them in tight spaces can, literally, push you against the wall.

Flow disturbance problems

Trying to jam too much equipment into too little space inevitably creates poor piping layouts. Putting elbows, expansions, reductions, or spiral piping close to instrumentation and other devices alters the process media’s tangential, radial, and axial velocity vectors. Flow disturbances result, including swirl, jetting, and velocity profile distortions, which negatively impact flowmeters, pumps and other equipment.

For best performance, flowmeters require straight pipe runs of 10 to 20 diameters, depending on the sensing technology. Irregular material flows caused by poor piping adversely affect the accuracy and repeatability of readings.

In pumps, control valves, and other critical process components, flow disturbances create cavitation that generates noise, excessive wear, and damage, ultimately resulting in premature failure. These same conditions can cause less obvious problems, reducing process media delivery capacity with associated end-product quality losses. Irregular liquid flow to pumps, in particular, can result in dry running conditions that lead to seal or bearing damage and result in expensive repairs or replacements.

The ideal process plant would have space for everything and everything would be installed exactly according to manufacturer specifications. In the real world, however, the objective generally is to squeeze out every last bit of process capacity and quality, delivering the lowest possible cost per unit of production.

Conditioning

Flow conditioners are one of the most practical ways to eliminate flow disturbances resulting from inadequate straight pipe runs and other poor pipe layouts. Types include honeycomb vanes, perforated plates, tabs, tube bundles, and vanes. Each has its application, depending on process media, equipment problem, pipe configuration, cost requirement, etc.

General guidelines for the best applications of flow technologies include:

  • Honeycomb vane-type conditioners are frequently found in HVAC or compressed air handling system applications where they provide modest flow profile corrections. They are available in many designs and materials which should be suited carefully to the specific use. Otherwise they can be maintenance intensive or require frequent replacement.

  • Perforated plates are a good choice in natural gas pipelines or other clean gas and liquid applications. They are simple to install and require no spool piece, but can be clog prone in dirty gas or solid-laden media. While effective, they generally have a higher head loss coefficient so may cause more pressure drop than tube bundles or tab-type products.

  • Tab-type flow conditioners are a good choice in clean or dirty gases and liquids because of the tabs tapered design. They provide excellent cross-mixing to remove swirl and correct velocity profiles with virtually no pressure-drop. They are the only technology that can be retrofitted into elbows. However, their design is unsuitable for most sanitary applications.

  • Tube bundles and vanes have been used for decades. Tube bundles reduce swirl in clean gases and liquids, but do not correct velocity profiles and are unsuitable for custody transfer applications. Vanes also remove swirl, but cannot isolate or remove flow irregularities.

When making your selection or consulting with a vendor, ensure you know these key process variables:

  • Viscosity range of the process media;

  • Solids content in the gas or liquid; and,

  • Tolerable pressure loss vs. conditioning effectiveness.

These elements are critical to final selection and proper installation.

Rugged applications

Tab-type flow conditioners have been proven effective in highly rugged conditions. For instance, a standard Vortab flow conditioner is a straight pipe fitted with a short section of swirl reduction tabs combined with three arrays of profile conditioning tabs. Combining both types of tabs creates a repeatable, flat velocity profile at the outlet. The technology also can be designed into an elbow flow conditioner. (See illustration.)

Tab-type flow conditioners are suitable for applications in many different processes:

Motors, drives, motion control

process control and Instrumentation

Irregular material flows caused by poor piping adversely affect the accuracy and repeatability of flow meter readings.Tab-type flow conditioners are effective at reducing swirl and velocity profile problems with minimal pressure drop. They also tolerate dirty media and solids content.

 

  • An offshore oil pumping station needed to add a pump to increase capacity, but since there was no room for the pump’s required straight pipe run, installers had to connect an elbow directly to the pump inlet. Placing a tab-type conditioner in the elbow solved the problem by ensuring properly conditioned flow entering the pump. This saved cost and freed precious real estate for other uses.

  • An electric power plant needed to add two identical 14-in. centrifugal pumps to feed water into its main boilers. Space restraints dictated making a 90° turn at the inlet. To make matters worse, after the elbow, the pipe size drops from 16 to 14 in. immediately at the pump inlet. Placing a tab-type flow conditioner in the elbow compensated for the lack of straight run and provided equally distributed flow entering the pumps.

  • A natural gas producer faced space limitation problems when retrofitting a pipeline pumping station with a new compressor. Existing underground piping precluded installing proper straight pipe runs required for the 3,500 hp unit. Instead of digging out of the problem, an elbow fitted with a tab-type flow conditioner was plumbed directly into the compressor’s inlet.

Straight thinking

If you’re planning a facility expansion or retrofit, examine the straight pipe run requirements of all equipment involved. Valves, pumps, compressors, and flowmeters can all be affected by flow disturbances caused by poor piping layouts. Such problems can be costly, resulting in poor end-product quality, equipment repairs or failures, and even line shut-downs.

When you’re simply out of room or when changing the piping configuration is cost prohibitive, flow conditioners are an excellent solution with a careful and informed selection.


Related reading


Author Information

Don Lundberg is a senior engineer at Vortab Co.,




No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
Each year, a panel of Control Engineering editors and industry expert judges select the System Integrator of the Year Award winners.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Learn how to create value with re-use; gain productivity with lean automation and connectivity, and optimize panel design and construction.
Go deep: Automation tackles offshore oil challenges; Ethernet advice; Wireless robotics; Product exclusives; Digital edition exclusives
Lost in the gray scale? How to get effective HMIs; Best practices: Integrate old and new wireless systems; Smart software, networks; Service provider certifications
Fixing PID: Part 2: Tweaking controller strategy; Machine safety networks; Salary survey and career advice; Smart I/O architecture; Product exclusives
The Ask Control Engineering blog covers all aspects of automation, including motors, drives, sensors, motion control, machine control, and embedded systems.
Look at the basics of industrial wireless technologies, wireless concepts, wireless standards, and wireless best practices with Daniel E. Capano of Diversified Technical Services Inc.
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
This is a blog from the trenches – written by engineers who are implementing and upgrading control systems every day across every industry.
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Case Study Database

Case Study Database

Get more exposure for your case study by uploading it to the Control Engineering case study database, where end-users can identify relevant solutions and explore what the experts are doing to effectively implement a variety of technology and productivity related projects.

These case studies provide examples of how knowledgeable solution providers have used technology, processes and people to create effective and successful implementations in real-world situations. Case studies can be completed by filling out a simple online form where you can outline the project title, abstract, and full story in 1500 words or less; upload photos, videos and a logo.

Click here to visit the Case Study Database and upload your case study.