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Batch reactor: characteristics, parts, applications

The batch reactor can be compared in its operation to a pressure cooker. The food is placed in the pot, the lid is closed, and the cooking process begins, which is nothing more than a chemical process. When the cooking of the food is complete, the lid of the pot is opened and the removal of the same begins.

Design and parts of a batch reactor. Source: Echis at English Wikipedia, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons

Compared to continuous reactors, batch reactors have the advantage of their versatility and cost of installation; although its operating cost is higher.

Characteristics of the batch reactor

Discontinuous load

The batch reactor works by discontinuous charges, that is, the different components of the chemical process (reactants) are introduced, allowing chemical reactions to take place.

After a certain time, the products are removed before starting a new chemical process. The recalled products would make up a batch, one for each reagent load.

System closed

A consequence of the above is to conclude that the batch reactor operates as a closed system; that is, during the performance of a chemical process in the reactor, there is no entry or exit of substances.

Non-steady state

The reactor operates in a non-stationary state, since the chemical composition of its interior varies over time. The concentration of the reactants decreases, while that of the products increases. This would not be the case if new reagents were constantly flowing into it.

Flexible operation

The batch reactor is very flexible in its operation, so that a certain equipment can be used for different purposes or applications.

The cost of purchasing and installing a bach reactor is less than the expense of a continuous reactor. However, the operating cost of the batch reactor is higher, caused by its intermittent operation, and which in some cases requires the intervention of an operator.

Reaction phases

The batch reactor is preferably used with liquid phase chemical reagents. But it can also be used in reactions involving solid and gaseous phases, as well as in phase mixtures, such as liquid-solid, liquid-gaseous, etc.

Small scales

The batch reactor is preferably used in small-scale operations and scientific research. In industry it has the difficulty of variability from one batch to another, and also the difficulty of achieving large-scale production.

Parts of a batch reactor

Container

The batch reactor consists of a container, generally made of stainless steel, which in some cases may be lined with porcelain. The reactor vessel has holes in the lid that closes it at the top through which the reagents from the chemical process enter the interior of the reactor.

Likewise, it usually has an outlet in its lower part for the liquids or products of the chemical processes experienced in the reactor. Furthermore, the container has outlets for the vapors and gases produced in the reactions, which must be eliminated to avoid an increase in pressure.

Stir motor

Batch reactors have a motor on their cover, equipped with a transmission system, which allows the movement of a stirring system, capable of keeping the reactor content homogeneous during the reactions.

This stirring system consists of a shaft, connected to the motor, and a set of blades attached to the shaft, whose shapes depend on the content of the reactor. The blades are arranged in such a way that the diameter they form is close to the inside diameter of the reactor.

Batch reactors are also usually equipped with a baffle system. This is made up of plates attached to the walls of the reactors, and which are impacted by the content of the containers mobilized by the stirring system, thus achieving a higher degree of homogenization.

Heating or cooling system

Chemical reactions that occur in reactors can be endothermic or exothermic. Therefore, for the reactions to take place without a change in temperature inside the reactors, their temperature must be regulated.

To this end, the reactor vessels are surrounded by a jacket-shaped cover, connected to a heating or cooling system, as the case may be, which allows the circulation of liquids to maintain a constant temperature.

This condition is necessary for optimal performance of chemical processes. In some cases, the cooling of the contents of the interior of the reactor is achieved through the use of a system of spiral tubes, adhered to the walls of the reactor vessels.

Applications

The batch reactor is used in small-scale industrial production, in scientific research in calorimetry studies, in crystallization, kinetics, polymerization, and synthesis. It is also used in the development of new products.

This reactor is used in the pharmaceutical industry where many drugs are made. It is also used in the initiation of the fermentation of some beverages.

It is used in the manufacture of polyols and polyglycols, polymers that are used as bases for paints, for the manufacture of molds, adhesives, coatings, sealants, pipe insulation and cold rooms. In addition, it is used in the sulfonation of aromatic hydrocarbons and in the combustion of solids.

Batch reactors are also used in the small-scale production of vinyl homopolymers at low temperatures. The reactor has been used in the production of hydrogen of biological origin from solid waste.

These reactors have been of benefit in the processing of toxic or high risk materials.

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