Agitated Cell Reactor (ACR)

In plug flow reactors (micro reactors, tubular reactors, pipe reactors, static mixers etc) the dispersion number, Reynolds number, pressure drop, mixing efficiency and heat transfer capacity are all affected by fluid velocity and channel geometry. This means that any change in residence time (or throughput) also changes other process conditions. This make plug flow reactors inflexible and often wasteful as process development tools. 

The ACR is a multi stage continuous reactor. It uses dynamic mixing which provides efficient mixing irrespective of throughput or residence time. The use of multiple discrete stages ensures good plug flow at low throughputs. The ACR offers good mixing, low pressure drop and good plug flow over a wide range of flow conditions. This makes it an ideal tool for scale up studies.

Patents pending

The Coflore ACR is a continuous reactor for laboratory and scale-up. Designed for throughputs of 10 grams to 2 kilograms an hour, it can handle reaction times of 5 seconds to >100 hours. Its versatility stems from 4 key design features:

• Dynamic mixing (as opposed to static mixing) - This permits throughput to be altered without affecting mixing efficiency. High Reynolds numbers can also be maintained at low throughputs.
• 10 discrete reaction stages linked by inter-stage channels - This minimises pressure drop at high throughputs and maintains good plug flow at low throughputs. This makes the reactor very flexible.
• Variable cell volume - The volumetric profile of the reaction cells can be modified with interchangeable inserts. This allows the residence time distribution to be optimised for zero, first or second order reactions.
• The reactor can be inverted for product discharge. This ensures full product recovery without the need for purge fluids.

Although the ACR has superficial differences to tubular reactors, it is an ideal development tool for such systems. It can generate high Reynolds numbers and good plug flow independently of throughput or reaction time. This allows the user to replicate process conditions in large PFRs (Reynolds number, dispersion number, surface to volume ratio) without wasting large quantities of product. Unlike tubular reactors, the user has the freedom to alter residence time without creating pressure drop problems or affecting flow/mixing conditions.

The Coflore Agitated Cell Reactor (ACR) is a compact, low cost CSTR. Product flows sequentially through 10 reaction cells via plug flow inter-stage channels. Within each reaction cell is a loose agitating element which generates mixing when the agitator block is oscillated. This agitation arrangement eliminates the need for rotating shafts and mechanical seals. The size of agitator inserts can be varied to control the volumetric capacity of the reaction cells allowing the operator to adapt the residence time distribution to suit the reaction. Each reaction cell has a sight glass which can be replaced with an addition point, sample point or monitoring device. At the back of the ACR is a heat transfer plate to control cell temperatures. The ACR reactor block is mounted on an oscillating platform which allows it to be shaken at speeds of 0.1-100 Hz.  Oscillation of the reactor generates efficient mixing irrespective of product throughput. The oscillating platform rotates through 180^° which allows the product to be discharged without the need for buffer fluids. This permits high product recovery and throughputs of as little as one reactor volume.

The ACR can be used as an alternative to a standard glass lab reactor. It offers better heat transfer capacity and better temperature control. It can tolerate a wide range of operating temperatures and pressures. By virtue of being a continuous reactor, it is generally safer and can deliver improved yields for some types of chemistry. For many applications, a plug flow reactor may be the ideal solution for the manufacturing scale operations. The user however is faced with a problem of evaluating the process during scale up. The ACR is an ideal tool during this intermediate stage. It offers a means of replicating the operating conditions in a large plug flow reactor (such as mixing and surface to volume ratios) within a very compact unit and without generating large quantities of product. The ACR is very compact and the operating length does not need to be varied for different reaction times.