Batch Reactors

ZAIN AHMED SIDDIQEE

CE_E07_103

BATCH REACTOR INTRODCTION:

In a batch reactor the reactants and the catalyst are placed in the reactor which is then closed to transport of matter and the reaction is allowed to proceed for a given time whereupon the mixture of unreacted material together with the products is withdrawn. Provision for mixing may be required.

Typical diagram of batch reactor

Typical diagram of batch In all batch type reactor there is a feed line from reactor where the reactants enters inside chamber •

•There is a vent and product out line as well •There is a stir used for agitation and throw out

mixing which is controlled •The pressure line is supplied from the top to maintain required pressure needed •The temperature control element is also required with sensor normally thermocouple or thermometer •Sometimes a cooling or insulation jacket is also supllied and in some cases heat exchanger coil all around the vessel

Different types of batch reactors Sequencial Batch Reactors(used in water treatment in mostly)

FED Batch Fed-batch reactors •Fed-batch is a production

technique in between batch and continuous fermentation. A proper feed rate, with the right component constitution is required during the process. •It is mostly use in

fermentation technique and different chemical processes having long residence time

Stirred batch reactors Stirred Batch Reactor: •It contains catalyst dispersed as slurry •There is a better contact b/w reactants

and catalyst in this type of reactor •This reactor is useful for substrate

solutions of high viscosity and for immobilized enzymes with relatively low activity

Semi Batch Reactor •A semi-batch reactor is operated with both

continuous and batch inputs and outputs. A fermenter, for example, is loaded with a batch, which constantly produces carbon dioxide, which has to be removed continuously. Analogously, driving a reaction of gas with a liquid is usually difficult, since the gas bubbles off. Therefore, a continuous feed of gas is injected into the batch of a liquid. An example of such a reaction is chlorination.

Usage of batch reactors 1. Small scale production 2. Intermediate or one shot production 3. Pharmaceutical 4. Fermentation

Kinds of Phases Present

1. Gas phase 2. Liquid phase 3. Liquid Solid

Mathematical Formulii

Advantages The advantages of the batch reactor lie with its versatility. A single vessel can carry out a sequence of different operations without the need to break containment. useful

when

This

is

particularly

processing, toxic or

highly potent compounds.

Advantages 1. High conversion per unit volume for

one pass 2. Flexibility of operation-same reactor

can produce one product one time and a different product the next 3. Easy to clean

Disadvantages 1. High operating cost 2. Product quality more variable

than with continuous operation

Batch Reactor Control The following are the reaction variables control in batch process :

Industrial examples ICI CHEMICALS PAKISTAN •chemicals used in a variety of industries including fertilizer, cement, polyester, oil and gas, plastics, nonchemical products like specialized fibers, solvents, adhesives and paint industries.  •Most of the chemicals are prepared on small scale production on the batch reactor •Some of these chemical are additives, polyols, glycols, water treatment chemicals, solvents etc.

References •http://userpages.umbc.edu/~gferre1/fedbatch.html

•http://books.google.com.pk/books?id=pnNc496xxEMC&pg=PA24

•http://www.rpi.edu/dept/chem-eng/Biotech-Environ/IMMOB/stirred

•http://en.wikipedia.org/wiki/Chemical_reactor#Semi-batch_reacto