Pharmaceuticals and Food Industry

 

Pharmaceutical Industry:

Pharmaceutical industry, the discovery, development, and manufacture of drugs and medications (pharmaceuticals) by public and private organizations.

The modern era of the pharmaceutical industry—of isolation and purification of compounds, chemical synthesis, and computer-aided drug design—is considered to have begun in the 19th century, thousands of years after intuition and trial and error led humans to believe that plants, animals, and minerals contained medicinal properties. The unification of research in the 20th century in fields such as chemistry and physiology increased the understanding of basic drug-discovery processes. Identifying new drug targets, attaining regulatory approval from government agencies, and refining techniques in drug discovery and development are among the challenges that face the pharmaceutical industry today. The continual evolution and advancement of the pharmaceutical industry is fundamental in the control and elimination of disease around the world.

Food Industry:

The food industry is a complex, global collective of diverse businesses that supplies most of the food consumed by the world's population. The term food industries covers a series of industrial activities directed at the processing, conversion, preparation, preservation and packaging of foodstuffs.

Food processing is the transformation of agricultural products into food, or of one form of food into other forms. Food processing includes many forms of processing foods, from grinding grain to make raw flour to home cooking to complex industrial methods used to make convenience foods. Some food processing methods play important roles in reducing food waste and improving food preservation, thus reducing the total environmental impact of agriculture and improving food security.

Primary food processing is necessary to make most foods edible, and secondary food processing turns the ingredients into familiar foods, such as bread. Tertiary food processing has been criticized for promoting over-nutrition and obesity, containing too much sugar and salt, too little fiber, and otherwise being unhealthful in respect to dietary needs of humans and farm animals.

Batch Reactor:

The batch reactor is the generic term for a type of vessel widely used in the process industries. Its name is something of a misnomer since vessels of this type are used for a variety of process operations such as solids dissolution, product mixing, chemical reactions, batch distillation, crystallization, liquid/liquid extraction and polymerization. A typical batch reactor consists of a storage tank with an agitator and integral heating/cooling system. These vessels may vary in size from less than 1 litre to more than 15,000 litres. They are usually fabricated in steel, stainless steel, glass-lined steel, glass or exotic alloy. Liquids and solids are usually charged via connections in the top cover of the reactor.

The usual agitator arrangement is a centrally mounted driveshaft with an overhead drive unit. Impeller blades are mounted on the shaft. A wide variety of blade designs are used and typically the blades cover about two thirds of the diameter of the reactor. Products within batch reactors usually liberate or absorb heat during processing. Even the action of stirring stored liquids generates heat. In order to hold the reactor contents at the desired temperature, heat has to be added or removed by a cooling jacket or cooling pipe. Heating/cooling coils or external jackets are used for heating and cooling batch reactors. 

Semi - Batch Reactor:

Semi-batch reactors occupy a middle ground between batch and continuous reactors. They are open systems like CSTRs and run on an unsteady-state basis like batch reactors. They usually consist of a single stirred tank, similar to a batch reactor. The half-pipe coil jacketed reactor shown below can be used in semi-batch operations.

An initial amount of reactants is charged into the reactor. The reactor is then started, and additional reactants are added continuously to the tank. The reactor is then allowed to run until the desired conversion is achieved, at which point the products and remaining reactants are removed from the tank and the process can be started once more.

Semi-batch reactors are not used as often as other reactor types. However, they can be used for many two-phase (i.e. solid/liquid) reactions. Also, semi-batch reactors are used when a reaction has many unwanted side reactions, or has a high heat of reaction. By limiting the introduction of reactants, potential problems are eliminated.

Continuous Stirred Tank Reactor:

Continuous stirred-tank reactors (CSTRs) are open systems, where material is free to enter or exit the system, that operate on a steady-state basis, where the conditions in the reactor don't change with time. Reactants are continuously introduced into the reactor, while products are continuously removed.

CSTRs are very well mixed, so the contents have relatively uniform properties such as temperature, density, etc. throughout. Also, conditions in the reactor's exit stream are the same as those inside the tank. Systems connecting several CSTRs are used when the reaction is too slow. Multiple CSTRs can also be used when two immiscible liquids or viscous liquids are present and require a high agitation rate.

CSTRs consist of a tank, usually of constant volume, and a stirring system to mix reactants together. Feed and exit pipes are present to introduce reactants and remove products. Stirring blades, also called agitators, are used to mix the reactants. A CSTR can also function as a loop reactor when a heated, pressurized fluid is injected into the system to facilitate the stirring. This allows for higher heat and mass transfer rates while simplifying maintenance because there is no agitator.

Continuous stirred-tank reactors are most commonly used in industrial processing, primarily in homogeneous liquid-phase flow reactions, where constant agitation is required. They may be used by themselves, in series, or in a battery. CSTRs are also used in the pharmaceutical industry as a loop reactor.

Fluidised Bed Reactor: 

Fluidized bed reactors are heterogeneous catalytic reactors in which the mass of catalyst is fluidized. This allows for extensive mixing in all directions. A result of the mixing is excellent temperature stability and increased mass-transfer and reaction rates. Fluidized bed reactors are capable of handling large amounts of feed and catalyst.

Before the reactor is started the catalyst pellets lie on a grate at the bottom of the reactor. Reactants are pumped into the reactor through a distributor continuously, causing the bed to become fluidized. The bed's behavior after initial fluidization depends on the state of the reactant. If it is a liquid the bed expands uniformly with increased upward flow of the reactant. This is called homogenous fluidization. If the reactant is a gas the bed will be non-uniform because the gas forms bubbles in the bed, resulting in aggregative fluidization. Sometimes these bubbles in coarse materials can grow larger than two-thirds of the bed's diameter, which can cause slugging. Slugging can result in variable pressures, vibrations in the bed, and heat transfer reductions. Increasing the velocity of the gas leads to a turbulent regime. In the fast fluidization regime the bed surface starts to disappear. Increasing the gas velocity further results in pneumatic transport, in which the bed is completely removed and the particles are uniformly spaced in the fluid. During this process the reactants react due to the presence of the catalyst pellets, forming products that are removed continuously.

Fluidized bed reactors are generally very large. They must be designed so that the fluid flowrate is sufficient to suspend the catalyst particles. The particles typically range in size from 10 - 300 microns. When designing a fluidized bed reactor, the catalyst life must also be taken into account. Most fluidized bed reactors have a separate compartment to regenerate the catalyst.

Fluidized bed reactors are commonly used in catalytic cracking processes. They are also used in the oxidation of naphthalene to phtalic anhydride, roasting of sulfide ores, coking of petroleum residues, and the calcination of limestone. They are often used when there is a need for large amounts of heat input or output, or when closely controlled temperatures are required. The fluidized bed reactors below are used in NASA's Jet Propulsion Laboratory for the removal of perchlorate and chlorinated solvent from groundwater.