Batch Reactors

ZAIN AHMED SIDDIQEE CE_E07_103

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is allowed to proceed for a given time whereupon the mixture of unreacted material together with the products is withdrawn.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.

BATCH REACTOR

Typical diagram of batch reactor

•In all batch type reactor there is a feed line from 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

Typical diagram of batch reactor

Sequencial Batch Reactors(used in water treatment in mostly)

Different types of batch reactors

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

FED Batch

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

Stirred batch reactors

•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.

Semi Batch Reactor

1. Small scale production

2. Intermediate or one shot

production

3. Pharmaceutical

4. Fermentation

Usage of batch reactors

1. Gas phase

2. Liquid phase

3. Liquid Solid

Kinds of Phases Present

Mathematical Formulii

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. This is particularly

useful when 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

Advantages

1. High operating cost

2. Product quality more

variable than with

continuous operation

Disadvantages

The following are the reaction variables control in batch process :

Batch Reactor Control

ICI CHEMICALS PAKISTAN•chemicals used in a variety of industries including fertilizer, cement, polyester, oil and gas, plastics, non-chemical 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.

Industrial examples

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

•http://books.google.com.pk/books?id=pnNc496xxEMC&pg=PA246&lpg=PA246&dq=stirred+batch+reactor(sbr)&source=bl&ots=_8H6CF43OP&sig=gychH_LN8qXHnPw5pLpTk1GlIjQ&hl=en&ei=z1r2SpafMsGSkQXE9tyyAw&sa=X&oi=book_result&ct=result&resnum=10&ved=0CDQQ6AEwCQ#v=onepage&q=stirred%20batch%20reactor(sbr)&f=false

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

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

References