E-Zine October 2016

Click here to read “So Many Pumps, So Many Applications... A Critical Application”

Recent innovations in pumping systems include the use of exotic materials for wetted parts. Pumps are now made of high-purity thermoplastics with ceramic impellers and shafts, making it possible to pump high-purity fluids and highly corrosive liquids. At least one company is working on a shaft-less, seal-less pump for corrosive applications, using the principles of magnetic levitation to operate the impeller. This would produce a "throwaway" pumping head that could be replaced rather than repaired, and reduces the chance of fugitive emissions of toxins and hazardous chemicals through leaking packing glands and seals.

Valve manufacturing companies have been experimenting with "smart" valves that can reduce or eliminate the need for a separate flow element, by combining a flow transmitter with the valve.

No matter what the design, however, if you want a working system, you have to select the right pump, the proper piping and valves, and the correct flowmeter and flow controller.

From Flow Control (January 2002)

How to Develop a Good Velocity Profile without Installing Straight Run

By David W. Spitzer

E-Zine October 2016

Manufacturers instruct users to install straight run upstream and downstream of their flowmeters. Is straight run necessary? Not really.

Many flowmeters are affected by the velocity profile upstream and/or downstream of the flowmeter. Other flowmeters are not affected at all.

The velocity profile describes the velocities and swirls that are present in a cross-section of a pipe. A good velocity profile generally consists of a non-swirling uniform fluid flow with symmetric point velocities in the cross-section. A typical velocity profile exhibits lower velocities near the pipe wall and higher velocities near the center of the pipe. Failure to develop a good velocity profile upstream and/or downstream of many flowmeters can affect their measurements and thereby adversely affect their performance.

Re-stated succinctly, many flowmeters can be affected by a distorted velocity profile. There a number of techniques that can be used to develop a good velocity profile. The most common approach is to install straight run upstream and downstream of the flowmeter where the fluid can sufficiently attenuate velocity profile distortion that may be present. Flowmeter manufacturers typically publish the amounts of straight run necessary for each of their flowmeters to measure accurately.

However there are other approaches that can be used to develop a good velocity profile. One such approach is to install a flow conditioner upstream of the flowmeter where a sufficiently good velocity profile is developed a short distance downstream of the flow conditioner. Flow conditioners are often applied when insufficient space is available to install the straight run specified by the manufacturer and/or when large amounts of velocity profile distortion are present. Different flow conditioner designs are used to reduce different types of velocity profile distortion. For example, some flow conditioners are more suitable to reduce swirl whereas other designs tend to reduce profile distortion.

Therefore, straight run is not strictly necessary if another technique is used to develop a sufficiently good velocity profile so as to not adversely affect flowmeter performance.

This article originally appeared in Flow Control magazine.

Quiz Corner: Which Actions Are Relevant to an Energy Conservation Program?

By David W. Spitzer

E-Zine October 2016

A. Sell energy conservation to management
B. Form a team to address energy conservation
C. Analyze plant utility bills and calculate the marginal cost of utilities
D. Identify viable projects
E. All of the above

Commentary
Energy conservation projects typically involve little risk because they generally exhibit returns that can be accurately calculated and verified. Many plants engage in this activity and then stop. Starting or re-starting an energy conservation program can seem overwhelming --- especially in an environment where energy prices are low or falling.

That said, energy conservation can not only save money but can also be environmentally responsible because energy that is not consumed does not adversely affect the environment.

Energy conservation projects can be randomly performed by individuals, but obtaining strong management support and forming a plant-wide energy conservation team usually leads to superior results. One of its first activities could be to calculate the marginal cost of purchased utilities such as natural gas and electricity as well as plant utilities such as compressed air, cooling water and steam. Having these marginal costs readily available tends to simplify calculations to determine the viability of projects identified by the team.

Answer E is correct.

Additional Complicating Factors
Identifying, justifying and implementing energy conservation should be an ongoing activity in the plant. Maintaining momentum for the effort can be difficult after the best energy conservation projects are implemented.

From Flow Control (October 2015)

ISSN 1538-5280