Article | Mixing & Agitation in food industry | PMG Engineering

Mixing & Agitation in food industry

Mixing and agitation refer to the process of combining two or more substances to form a homogeneous mixture by using mechanical means. In the food industry, mixing and agitation are commonly used to blend various ingredients to form a uniform mixture, dissolve solids into liquids, and create emulsions or suspensions.

Mixing and agitation can be performed using different types of equipment, such as mixers, agitators, blenders, and homogenizers. These devices create turbulence and shear forces, which cause the components of the mixture to intermingle and interact with each other.

Mixing and agitation play a critical role in the quality, consistency, and efficiency of many food products. For example, mixing is essential in the production of baked goods, such as cakes and bread, to ensure the dough is evenly distributed and the final product has consistent texture and structure. Agitation is also used in the production of dairy products, such as yoghurt and cheese, to ensure a uniform distribution of bacteria and to promote the growth of cultures

1. Working Principle

The working principle of mixing and agitation involves the application of mechanical energy to a fluid or mixture to achieve a uniform distribution of the components. Mechanical energy is usually applied to the fluid using a mixing or agitation device, such as an impeller or propeller, which rotates in the fluid. This motion creates turbulence in the fluid, causing the components to mix and disperse evenly throughout the mixture.

The effectiveness of mixing and agitation depends on various factors, such as the type of mixing device, the speed of rotation, the viscosity and density of the fluid, and the desired mixing result. Different types of mixing devices can be used for different applications, such as high-shear mixers for emulsifying or homogenizing, and low-shear mixers for gentle mixing and blending.

Mixing and agitation are widely used in the food industry for various applications, such as mixing ingredients to prepare a recipe, blending flavours or colours, and mixing inclusions into a product. These processes help ensure consistent quality and uniformity in food products.

2. Types of Machines

There are several types of mixing and agitation machines that can be used for different applications, including:

2.1. Paddle mixers: These mixers use paddles or blades to mix the ingredients. They are

commonly used in the food, chemical, and pharmaceutical industries.

2.2 Ribbon mixers: Ribbon mixers have two counter-rotating ribbon-like blades that mix the

ingredients. They are suitable for mixing dry powders, granules, and some liquids.

2.3 High-shear mixers: High-shear mixers use high-speed blades or rotors to mix the

ingredients. They are used for mixing emulsions, suspensions, and other high-viscosity .

2.4 Planetary mixers: Planetary mixers have a central mixing blade that rotates on its own axis

while orbiting around the mixing bowl. They are used for mixing pastes, doughs, and other

viscous materials.

2.5 Static mixers: Static mixers do not have any moving parts and rely on the fluid flow to mix

the ingredients. They are used for mixing liquids and gases.

2.6 Homogenizers: Homogenizers use high pressure to break down particles and mix the

ingredients. They are commonly used in the dairy industry for milk homogenization.

2.7 Agitators: Agitators use a rotating impeller to mix the ingredients. They are commonly

used in tanks and reactors for liquid-liquid and liquid-solid mixing.

2.8 Tumble mixers: Tumble mixers use a rotating drum or container to mix the ingredients.

They are commonly used for mixing powders, granules, and other dry materials.

3. Components:

Agitators are mechanical devices that are used to mix or blend various substances, such as liquids, powders, and slurries.

The components of an agitator can vary depending on its design and application, but some common components include:

· Impeller: The impeller is the rotating component of the agitator that creates fluid motion and

mixes the contents of the vessel. Impellers can have various shapes, such as propellers,

turbines, anchors, and helical.

· Shaft: The shaft is the component that connects the impeller to the motor or gear reducer. It

is typically made of stainless steel and has various lengths and diameters depending on the

size of the vessel and the power of the agitator.

· Motor or Gear Reducer: The motor or gear reducer is the component that provides power to

the agitator. It can be an electric motor, pneumatic motor, or hydraulic motor, depending on

the application and the environment.

· Seal: The seal is the component that prevents fluid leakage from the vessel through the shaft.

There are various types of seals, including mechanical seals, packing seals, and lip seals.

· Mounting: The mounting is the component that connects the agitator to the vessel. It can be

a flange, clamp, or bracket, depending on vessel's design and the agitator's size and weight.

· Baffles: Baffles are stationary components that are installed in the vessel to direct the fluid

flow and prevent vertexing. They can be flat, curved, or angled, depending on the application.

· Support: The support is the component that holds the agitator in place and prevents it from

moving or vibrating excessively. It can be a bearing, pedestal, or bracket, depending on the

agitator's design and the vessel's size and weight.

· Drive Train: The drive train is the component that connects the motor or gear reducer to the

shaft. It can be a belt, chain, or gear, depending on application and the power requirements.

· Control System: The control system is the component that regulates the speed and direction

of the agitator. It can be a manual control, such as a hand crank or lever, or an automatic

control, such as a programmable logic controller (PLC) or a variable frequency drive (VFD).

4. Application Industries

· Mixing and agitation equipment find their applications in various industries. Some of the

industries that use mixing and agitation machines are:

· Chemical Industry: Mixing and agitation equipment are widely used in the chemical industry to

mix and blend chemicals to produce different products.

· Pharmaceutical Industry: The pharmaceutical industry uses mixing and agitation equipment to

mix and blend ingredients to produce medicines.

· Food and Beverage Industry: Mixing and agitation machines are used in the food and beverage

industry to mix and blend ingredients to produce different food and beverage products.

· Water Treatment Industry: Mixing and agitation equipment are used in the water treatment

industry for various processes, such as flocculation, coagulation, and pH adjustment.

· Petrochemical Industry: The petrochemical industry uses mixing and agitation equipment to

blend different chemicals to produce petrochemical products.

· Paint and Coating Industry: Mixing and agitation equipment are used in the paint and coating

industry to mix and blend different ingredients to produce paints and coatings.

· Biotechnology Industry: Mixing and agitation machines are used in the biotechnology industry

for various processes, such as fermentation, cell culture, and protein expression.

· Cosmetics Industry: The cosmetics industry uses mixing and agitation equipment to mix and

blend ingredients to produce various cosmetic products.

· Mining and Minerals Industry: Mixing and agitation equipment are used in the mining and

minerals industry for various processes, such as leaching, flotation, and precipitation.

5. References:

· https://www.flexachem.com/mixing-technology/agitator/

· https://letsfab.in/agitators-or-mixers/

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