A3.1 - From Flowmeter to Advanced Process Analyser

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
A3 - Flow Measurement
D. Schrag - Mettler Toledo, Nänikon (Switzerland), K. Hencken, A. Andenna - ABB Switzerland Ltd., Baden Dättwil (Switzerland)
67 - 72


Flowmeter used to measure one process parameter:
the flow rate of the fluid. Accuracy, robustness and interconnectivity have been a main focus of new developments in the past.
With the availability of enormously increased computation power the trend has shifted in the direction of diagnosing the industrial process in more detail rather than measuring the one flow parameter only. This talk will point out important process indicators and show techniques to measure them based on different flowmeters to give a better knowledge of the process condition.
Fouling of equipment is for many industrial applications an important deterioration process making it necessary to clean the system regularly. Scheduling a shutdown of a process for maintenance is difficult without on-line knowledge of the fouling condition. But it has been shown that the thickness of fouling layers can be measured with a thermal mass flowmeter for gaseous fluids and with magnetic flowmeter for liquids based on impedance spectroscopy. This allows for a better planning of system cleaning and a better control of the process by compensating the influence of fouling.
Gas bubbles in liquid media are an important and searched-for indicator for the process quality. The reason for gas content in a liquid can be a chemical reaction, cavitations at inlets or outlets or leakage due to the tubing. Another important area is the detection of air inflow, e.g., when emptying storage containers, where air bubbles damage or even destroy the pumps. The detection enables a fast stop of the process and saves cost immediately. First products are now being introduced to the market. This talk will show techniques for magnetic flowmeters to measure gas bubbles in addition to the flow rate.
Magnetic flowmeter contain two electrodes to measure induced voltage. Conductivity measurements using a magnetic flowmeter enable to monitor changes in the media. This allows differentiating, e.g., the cleaning liquid from the process media. We will explain techniques and limitations for the measurement of this additional parameter using a two electrode technique. Pumps are used to transport liquids in continuous processes. These pumps age over time. One indication of their upcoming failure are vibrations. It has been shown in that measurement of system vibration using a vortex flowmeter is possible due to the specific behavior of vortices that is different from those of vibrations.