Liquid-Liquid

Throughout industry components are mixed in stirred vessels or pipes. The challenge is to determine exactly how well the ingredients are being mixed.

Factors such as the composition and nature of the ingredients, the position, speed and design of the stirrer and the structure of the vessel all contribute to mixing effectiveness.

Any reduction in mixing effectiveness:

- may increase the mixing time with consequential reduction in capacity

- increase the energy consumption

- reduce the yield and quality of the downstream processes.

The challenge is to improve understanding and detailed knowledge of the mixing and hence improve performance and availability. Often the structure is complex and the nature of the ingredients and the operating conditions make visual inspection either impossible or hazardous.

ITS has successfully developed and applied Electrical Resistance Tomography (ERT) to measure the performance of mixing systems.
 

In liquid-liquid mixing stirred tank up to 8 x 16-electrodes can be used as shown below:

These are connected to an Industrial Tomography Systems ERT instrument designed and established to measure and display ERT data. Each 16-electrode ring of electrodes generates a conductivity map of the cross-section at that point as shown above.

P1 to P8 represent the 8 measurement planes from the top to the bottom of the vessel. Mixing patterns and times can be determined by injecting a high conductivity tracer into the base of the mixer.

The conductivity map is one in a series showing the progress of the tracer as it is mixed in the vessel.

A colour scale is used to show variations in conductivity with blue representing the conductivity of the bulk fluid and red indicating the high conductivity tracer. A blue circle measures no mixing, shades of
green measure partial and red measures total mixing.

Key benefits include:

It has been widely demonstrated that ERT technology can be applied to a range of mixing processes. The benefits to the customers are:

• At the R&D stage of mixing development, improved process understanding and validation of CFD models to aid process design and scale-up.

• Through measurement improved control and product quality in industrial reactors.

• Higher yields through improved mixing with shorter mixing time and less energy consumption.

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