Typical Applications

EIT can be applied off-line to monitor the performance of stand-alone equipment, or used for on-line measurement, control and analysis of industrial processes [1]. It can therefore be used in its own right to monitor mixing, separation, flow and reactor dynamics (time-evolving concentration fields and implementation of velocity fields) of both single and multiphase processes [2, 3, 4], which despite years of investigative research are still not fully understood. A schema was proposed to facilitate the use of IPT based upon the boundary conditions of a process [5]. Three types of boundary condition were identified to aid in the determination of tomographic layout: I). Volume restricted A (forced movement of a dominant phase, e.g. stirrer agitation/introduction of secondary phase causing movement) requiring multiple planes to image the mixing/reaction process; II). Volume restricted B (similar to type I, although the moving phase passes through a structured medium phase), commonly requiring multiple planes for detailed process observation; and III). Boundary limitations (phase(s) move principally in one direction) necessitating only a single plane array to image concentration profile in cross-section confined flow. These are summarised in Table 1 for a range of industrial applications.


Table 1 . Comparision of EIT applications, key attributes and their relative industrial users

Application

Method (Boundary Cond.)

Derivative [Example Reference]

Key Attributes of EIT

Industrial Impact

Separation

Fluidised Beds (III)

Solid/Gas/Liquid [6, ,7]

Used to qualify/quantify 3D multiphase flow system dynamics

Chemical, Pharmaceutical

Hydrocyclones (I)

Fine slurry treatment, Refining of china clay [8]

Fault detection, measurement of air-core size (for different operational conditions), calculation of solids concentration.

Mineral Processing

Filtration (III)

Solid-Liquid pressure filtration [9, 10, 11, 12]

Identify malformation, performance of filter cakes, monitor liquid level, provide real-time info on end point of filtration and drying

Chemical, Pharmaceutical

Mixing

Stirred Vessels – Batch/Continuous Feed (I)

Solid-Liquid [13,14,15]

Improved understanding and quantifying of mixing phenomena, improved process control and equipment design

Pharmaceutical, Fine Chemical

Liquid-Liquid 16,17,18]

Understand how evolving concentration fields influence chemical selectivity as a function of mixing dynamics

Chemical, Fine Chemical

Gas-Liquid [19,20,21]

Identify gas hold-up, mixing processes at plant scale, impeller performance

Fine Chemical

Gas-Solid [14]

Identify gas-solid distributions, gas hold-up in stirred tanks

Chemical

Transport. & Flow Charactn.

Hydraulic Conveying (III)

Solid-Liquid flows [22, 23, 24]

Monitor suspension/distribution of solid particulates (inc. slurry transportation)

Mineral Proc., Nuclear Reproc., Dredging

Liquid-Liquid flows [25, 26]

Measurement of volume fraction and flow velocity distribution

Oil Field Pipelines

Pneumatic Conveying (III)

Gas-Solid flows[27,28]

Demonstrate 3D flow patterns in horizontal and vertical pipes, inc. identification of slugs/plugs.

Chemical

Gas-Liquid [29]

Imaging of slug/plug/stratified flow, flow velocity in horizontal/vertical pipes

Oil Field Pipelines

Packed Beds (II)

Column/Heap leaching [30, 31]

Monitor flow of leachate through packed beds, map hydraulic flow characteristics to optimise mineral recovery/reduce residence times

Mineral Processing

Reactors

Bubble Column Reactor (I)

Gas-Liquid chemical reaction [32,33]

Permit improved process control of bubble column reactor - minimise gas hold-up and increase gas interfacial area

Chemical

Crystallisation (I)

Crystallisation from ethanol [34]

Monitor gas hold-up, on-set and progression of crystallisation.

Chemical, Pharmaceutical

Stirred Vessel Reactor (I)

Hydrolysis of ethyl acetate [35]

Investigate progress of chemical reaction of Active Pharmaceutical Ingredients within a stirred process vessel

Pharmaceutical

Condensation Reaction (I)

Polymerisation of nylon [36]

Monitor rate of polymer chain growth, provide a means to effectively control/improve process efficiency

Chemical

Precipitation Reactors (II)

Precipitation of nitric acid [37]

Optimise feed positions and minimise peak concentrations of reactants

Chemical, Pharmaceutical

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 





















References