Batch reactor

In such cases, however, they may not be referred to as reactors but rather with a term specific to the function they perform (such as crystallizer, bioreactor, etc.).

[1] Many batch processes are designed on the basis of a scale-up from the laboratory, particularly for the manufacture of specialty chemicals and pharmaceuticals.

[2] A typical batch reactor consists of a pressure vessel with an agitator and integral heating/cooling system.

The usual agitator arrangement is a centrally mounted driveshaft with an overhead drive unit.

Where viscous products are handled, anchor shaped paddles are often used which have a close clearance between the blade and the vessel walls.

Despite significant improvements in agitator blade and baffle design, mixing in large batch reactors is ultimately constrained by the amount of energy that can be applied.

On large vessels, mixing energies of more than 5 W/L can put an unacceptable burden on the cooling system.

Within the chemical and pharmaceutical industries, external cooling jackets are generally preferred as they make the vessel easier to clean.

It has to be recognized however that large batch reactors with external cooling jackets have severe heat transfer constraints by virtue of design.

The half-coil jacket is made by welding a half pipe around the outside of the vessel to create a semi circular flow channel.

The constant flux jacket has very fast temperature control response (typically less than 5 s) due to the short length of the flow channels and high velocity of the heat transfer fluid.

Batch reactors are often used in the process industry; in wastewater treatment, as they are effective in reducing biological oxygen demand (BOD) of influent untreated water;[3] in the pharmaceutical industry; in laboratory applications, such as small-scale production, inducing fermentation for beverage products, and for experiments of reaction kinetics and thermodynamics; etc.

Common issues ascribed to batch reactors are their relatively high cost and unreliability in terms of product quality.