Pneumatic Conveying

Pneumatic conveying is a specific case of multiphase flow.

A solid is transported along a pipe using air under pressure as the fluid.

The air effectively carries the solid along the pipe. To enable the air to carry the solids they are normally in the form of very small particles and the air velocities are quite high.

The challenge in designing and operating such systems is to ensure a sufficiently high air velocity and turbulence to ensure the fine solid particles do not “drop out” of the air steam and settle on the bottom of the pipe. Once settled the particles may agglomerate and become much more difficult to transport.

The measurement priority is to measure both the mass velocity along the pipe and the distribution across the pipe from outside the pipe. Any measurement system inside the pipe would disturb the flow; cause eddies and is a source of issues in its own right.

The m3000 is used with circular sensors for pneumatic conveying.

Electrical Capacitance Tomography

Electrical Capacitance Tomography (ECT) is a measurement technique for obtaining information about the contents of process vessels and pipelines. Multiple electrodes are arranged around the boundary of the vessel at fixed locations in such a way that they do not affect the flow or movement of materials. For electrically insulating pipes the electrodes can be mounted externally and for electrically conducting pipes the electrodes must be mounted internally.

A typical application is real time monitoring of multicomponent flows within pipelines. Specific applications where ECT has been successfully exploited include solid/gas and liquid (organic)/gas systems such as fluidised beds, pneumatic conveying and multi-phase flow. In principle, ECT can be used to investigate and monitor any process where the main continuous phase is non- conducting and the other phases and components have differing values of permittivity.

Key benefits include:

• determine flow conditions and how these vary through time

• diagnose fault conditions

• characterise mass flow

Register to access our "Flow" case studies available from the Download section on the right.

Register to access our "Flow" case studies available from the Download section on the right.

Publications:

Jaworski AJ and Dyakowski T (2001) Application of electrical capacitance tomography for measurement of gas-solid flow characteristics in a pneumatic conveying system, Measurement Science and Technology, Vol. 12, 1109-1119

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