Entrained Gas Management (EGM)

EGM was developed for OPTIMASS Coriolis mass flowmeters to overcome problems caused by air or gas entrainments in a liquid. Powerful control algorithms allow the flowmeter to maintain operation over a wide range of gas fractions and complex flow conditions, even during a complete transition from a pure liquid phase to a gas phase and back. Mass flow and density measurements remain stable and continuous, which has been demonstrated in batch/ loading/ empty-full-empty applications.

Technology pioneer with over 8 years of experience
Standard for all OPTIMASS flowmeters without extra cost
Continuous measurement through complete transition from pure liquid phase to a gas phase and back (full-empty-full)
Process diagnostic: reliable detection and indication of 2-phase flows, air/gas entrainments

Entrained gas - required or unwanted?

Entrained gas may either be required for the process or the product (e.g. with aerated products) or occur as an unwanted side-effect caused by:

Leaking pumps
Cavitation
Vaporisation
Mixing of liquids
Empty-full-empty applications
Top filling tanks with long drops

How entrained air or gas affects the Coriolis flow measurement

With conventional Coriolis mass flowmeters, difficulties arise with entrained air or gas in the liquid, e.g. overreporting, or maintaining measurement. This is because the entrained air or gas affects the measurement.

Without entrained gas, the measuring tubes in the Coriolis mass flowmeter have the desired regular oscillation. Gas entrained in the liquid dampens this regular oscillation, and as the gas content increases, the oscillation can come to a complete stop.

To overcome this, KROHNE has developed powerful control algorithms for the OPTIMASS series of Coriolis flowmeters, and implemented them in a synthesised drive control.

Continuous operation even with complex flow regimes

The difficulty of measuring a liquid with entrained gas increases with the gas volume fraction (GVF). A number of other process factors such as temperature, increased viscosity, pressure, and the relative velocity between liquid and gas also affect the resulting flow regime.

EGM technology allows the flowmeter to maintain the oscillation with complex flow regimes. Even during a complete transition from a pure liquid phase to a gas phase and back, i.e. from 0 to 100% gas content, the device will continue to operate.

Benefits

EGM technology presents a number of advantages for your process:

Considerable improvements with plant start-up and shut-down, troubleshooting in the process: no more plant standstill due to gas bubble disturbance of meters
Uninterrupted measuring operation for coordinated dosing procedures without downtime
Reliable detection and indication of 2-phase flows or air/gas entrainments in the process
Added reliability for safety critical control functions (SIS)
Gas separators can be much smaller or even be omitted

Watch our EGM Video

Applications

Typical applications for OPTIMASS flowmeters with EGM are:

Chemical

Production of polyurethane foams

Oil & Gas

Crude oil production
LNG loading/unloading

Food & beverage

Spinach production
Ice cream production
Yoghurt production
Mayonaise production
Beer production

Mass or density – both are possible even with gas entrainment

Density measurement of single-phase fluids is common practice, but for traditional meters it becomes challenging with entrained gas. In many applications where entrained gas is present, OPTIMASS flowmeters with EGM show excellent performance and repeatability for process control, batching, loading, unloading and transfer measurement.