Tuesday, May 31, 2016

The Coriolis Effect Simply Explained. And Then Not So Simply Explained.

This video very simply (and very elegantly) demonstrates the Coriolis Force through the use of a ordinary garden hose.

An Now the Not So Simple Explanation

This force occurs, when the medium being measured is flowing at velocity ν through a tube that is rotating around an axis perpendicular to the direction of flow at angular ϖ.
coriolis force

When the medium moves away from the axis of rotation it must be accelerated to an increasingly high peripheral velocity. The force required for this is called Coriolis force, after its discoverer. The Coriolis force reduces the rotation. The opposite effect occurs, when the medium flows towards the axis of rotation. Then the Coriolis force amplifies the rotation.

The formula for the Coriolis force is as follows:
coriolis force

The entire measurement tube is deformed slightly by the Coriolis forces, in the way shown. This deformation is registered by movement sensors at points S1 and S2 .

For practical exploitation of this physical principle, it is sufficient for the tube to perform sympathetic oscillations on a small section of a circular path. This is achieved by exciting the measurement tube at point E by means of an electromagnetic exciter.

Coriolis flowmeters use the oscillating movement of two symmetric metal tubes that are made to vibrate from an internal driver coil.  When liquids or gases flow through the tubes, a phase shift occurs (like you see in the hose) and pickups measure the “twist” and then relate that value to the actual flow. In other words, the amount of twist is proportional to the mass flow rate of fluid passing through the tubes. The greater the twist, the larger the distance between, and the greater the flow.

The general construction of a Coriolis mass flowmeter looks like the following:
Coriolis flowmeter
Coriolis flowmeter diagram (Yokogawa)

Wednesday, May 25, 2016

Improve Process Control Security Using Annunciators as Watchers

ronan annunciators for security
Use annunciators for added security
Software-based systems are vulnerable to cyber attacks. Most of the industrial control networks (CAN, PROFI, Control Area, Ethernet and RS485) connect to the internet or other computer networks which are not fully protected from hackers and viruses. Present day industrial DCS/PLC control systems come with redundancy systems to eliminate shutdowns in case of DCS/PLC hardware failures. However, this does not protect your DCS/PLC system from any type of cyber attack. Without proper protection, the safety and/or operation of your plant or business are put at great risk.

The document below describes how using a stand-alone annunciator system will will work as a failsafe for DCS/PLC/SCADA systems and improve .

Monday, May 16, 2016

An Economical, No Maintenance Gas and Liquid Flow Measurement Solution for Tight Spots

Wafer-Cone Internal View
Engineers with small line size processes rely on the versatile are challenged finding a flowmeter with accuracy and repeatability. Many times orifice plates are specified for the job. An excellent alternative to an orifice plate, and one that should be carefully considered, is the Wafer-Cone, manufactured by McCrometer.

Unlike an orifice plate, the Wafer-Cone has no sharp edges so extensive maintenance and inspection are not required. The flangeless Wafer-Cone® is a space-saving unit is that is easy to install and ideal for tight-space installations and retrofits.  The cone conditions the flow so the Wafer-Cone requires minimal upstream or downstream pipe runs and can be installed virtually anywhere in a piping system.

Ideal for small line sizes and with no moving parts, no replacement parts or scheduled maintenance,
Components of Wafer-Cone
this meter offers a low cost of ownership and long life.

This device also offers interchangeable cones for flexibility in accommodating changing flow conditions without the need for recalibration. When flow conditions change over time, the cone can be removed and replaced with a cone at a different beta ratio eliminating the need to buy a new meter.

Finally, the Wafer-Cone is available with remote or direct mount configuration. The direct mount option minimizes installation labor while ensuring accuracy. Direct mounting the transmitter eliminates impulse lines, which not only lowers installation costs but also reduces potential leak points by more than 50 percent. Simple plug-and-play mounting ensures the meter is installed correctly the first time and eliminates a potential source of ow measurement errors.

Wafer-Cone with Transmitter
with Transmitter
Common applications are:
  • Natural Gas Wellheads
  • Gas, Water, and CO Injection
  • Gas Lift
  • Compressor Anti-Surge
  • Fuel Gas
  • Separator Discharge
  • Biogas Reactors
  • Cooling Systems
  • Plant HVAC
  • Process Gas Lines
Advantages of the Wafer-Cone
  • No straight pipe runs
  • Maximum flexibility
  • Economical
  • Accuracy to +/- 1%
  • Repeatability to 0.1%
  • Machineable in any material
  • No moving parts, low maintenance

Friday, May 6, 2016

Accurate Thermal Metering Using Non-Invasive Technology For Building HVAC Energy Management

BTU meter non-invasive ultrasonic technology
Specialized Ultrasonic Flow Meter for BTU Metering
Courtesy Flexim
The modern business climate has, for some now, been spooling up demand for accountability and, even more so, efficiency. Whether you think of efficiency as "doing more with less" or just avoiding the waste of financial, human, or natural resources the end result is the same and calls for similar prerequisites.

We live in a society of buildings, each with a mapped out function. Most buildings are predominantly occupied by people, bringing a requirement to maintain temperature, relative humidity, and air quality at levels of suitable comfort for human occupants. The energy consumption involved with providing that level of comfort stands as a bold line item in the operating expense ledger for any building. That is where accountability and efficiency come in. It is in the building stakeholders' interest to have knowledge regarding rates and quantity of thermal energy usage, as well as efficiency measures of delivered output per unit of input energy.

HVAC (Heating, Ventilation, Air Conditioning) primarily is an endeavor that generates and moves thermal energy throughout an enclosed space. Commercially available technology now allows a building operator to accurately measure that movement of thermal energy throughout a system or building. The process is generally called BTU metering and has a number of justifiable benefits.

  • Real time equipment performance measurement.
  • Sub metering can indicate specific areas of consumption.
  • Ability to directly bill multiple tenants in a single building for their thermal energy usage.
  • Monitor and balance energy flows.

BTU metering essentially involves inlet and outlet temperature measurement of heat transfer liquids, along with their flow rate. While the principle is simple, the intricacies of the measurement methods and equipment accuracy can have a substantial impact on the accuracy, and thus the benefit, of the measurement data. Additionally, adding more instrumentation to an already complex system can create an additional on-going maintenance and calibration burden to retain the necessary levels of accuracy and function. Success at gaining the benefit of the performance data while minimizing the additional maintenance burden due to the instrumentation should be the goal.

One solution calls for the use of clamp on ultrasonic flow meters to measure liquid flow, coupled with temperature measurement in a single unit that will perform necessary calculations and provide output data in useful engineering units. An overarching benefit of the clamp on meter is its non-invasive nature, allowing its retrofit to in-place systems with no disturbance to existing piping. Here are some other characteristics of a highly effective BTU measurement unit:
  • No wear mechanism as part of the flow measurement unit
  • Traceable accuracy of flow and temperature measurements
  • Simple installation in new or retrofit applications without disruption to system operation
  • Reliable and maintenance free operation
  • Accurate measurement from near zero flow rate to maximum system flow
  • Stable sensing with no zero drift
  • Communications protocol to match building energy management system
  • Large storage cache for data, in case of communication failure
  • Common output signals, 4-20 ma or other, usable with selected ancillary equipment
Selecting the right equipment or instrumentation is the most important step along the path of adding measurement capability to increase efficiency. Without a solid stream of reliable data, useful decisions become difficult. Contact a product application specialist and share your requirements and goals. Combining your process and system knowledge with their product application expertise will produce a good outcome.