Many process industries, such as oil and gas, petrochemicals, water and wastewater treatment, pharmaceuticals, and food processing, require the precise mixing of two or more liquids. Static mixers are among the most efficient mixing devices and are becoming increasingly popular in these applications. Unlike mechanical mixers, which have moving parts and require a lot of energy to rotate, static mixers have no moving parts and rely solely on the force of the liquid flow for mixing .
But how exactly do these devices work? In this article, we’ll explore the operating principle, components, advantages, and areas of application of static mixers.
Definition of a fixed mixer
A static mixer is a tubular structure equipped with multiple elements or blades of a specific shape (spiral, cruciform, or corrugated). These elements create shear and vortex motions in the fluid flow. This process ensures uniform mixing of materials throughout the flow . Essentially, a static mixer utilizes a clever design to convert the kinetic energy of the fluid flow into mixing energy.
Structure and main components
A food processor typically consists of three main parts:
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Pipe or coupling:
This part is typically made of stainless steel, PVC, polypropylene, or other corrosion-resistant materials. It is often tubular in shape and is suitable for industrial piping. -
Motor element:
the solid core of the motor. Can be constructed in several ways:-
spiral
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Z-shaped or cross-shaped blade types
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Radial or corrugated:
The choice of design depends on the type of fluid, viscosity, flow rate and mixing purposes.
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Edge and end connections:
Edge or end connections are often used to facilitate connection to process lines.
How a food processor works
Stationary mixers operate on the principle of shear mixing . After entering the mixing tube, the liquid enters the first element, which divides it into two or more streams. Each stream is separated and recirculated in the next element. By repeating this process in several successive elements, the liquid layers merge and eventually form a homogeneous mixture.
To put it simply:
Each element interrupts the flow and redirects its movement so that the different liquids come into better contact with each other.
In laminar flow, this separation and rotation increase the contact area between the two phases.
In turbulent flow, these factors cause stronger turbulence and faster mixing.
Types of stationary mixers
Stationary mixers are divided into several categories depending on their internal structure and area of application:
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Screw mixers:
The screw elements rotate clockwise and counterclockwise. Ideal for mixing medium- to high-viscosity liquids. -
X-grate agitators:
Made from X-shaped metal or plastic plates that create a lateral flow. Ideal for quickly mixing high-flow materials. -
Corrugated plate mixer:
Used in some industries for mixing gases and liquids or liquids and solids. -
Injection mixer:
In this type, the second material is injected directly into the stream and passes directly through the elements to ensure rapid mixing.
Advantages of using stand mixers
Due to their simple design, ease of use and the fact that they do not require an external power source, stationary mixers offer several advantages over mechanical mixers:
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No moving parts: virtually maintenance-free.
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Low energy consumption: The mixing energy is provided by the liquid itself.
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Easy to install: Can be installed anywhere on the pipe.
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Consistent and repeatable performance: The quality of the mixture remains constant over time.
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Suitable for use in potentially explosive environments: Since no motor or power is required, it is safe in fire-hazardous environments.
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Suitable for a wide range of fluids: from gases and light liquids to viscous liquids and smooth materials.
Factors that influence efficiency
To achieve optimal performance, several important factors must be considered when designing and selecting fixed mixers:
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Flow type (laminar or turbulent)
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Viscosity of liquids
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Volume ratio of ingredients
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Length and number of elements
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Pipe diameter and flow rate
In general, more elements result in greater mixing, but also a greater pressure drop. Therefore, a balance must be found between the degree of mixing and the pressure drop .
Stationary mixers
Stationary mixers are used in numerous industries, including:
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Oil, gas and petrochemical industries: Used to mix chemicals pumped in pipelines, blend additives, or standardize flow rates.
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Water and wastewater treatment plants: to provide disinfectants such as chlorine or coagulants.
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Food industry: Standardization of ingredients in the production of beverages, sauces and dairy products.
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Pharmaceuticals and biotechnology: Used for diluting solutions and mixing reagents.
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Polymer and resin production: for precise mixing of raw materials during the polymerization process.
Maintenance and productive life
Since stationary mixers have no moving parts, maintenance is minimal. Simply ensure that the component surfaces are clean and the flow channels are free of obstructions . Regular cleaning is recommended for processes involving viscous or easily contaminated materials.
The service life of a stationary faucet is typically 10 to 20 years , depending on the valve body material and operating conditions. Alloys such as 316L stainless steel or Hastelloy are recommended for corrosive environments.
Compared to mechanical mixers
| Special feature | Stand mixer | mechanical engine |
|---|---|---|
| moving parts | NO | Yes |
| Energy demand | NO | Yes |
| Maintenance costs | too low | relatively high |
| Hybrid control | Design in connection with | Refers to speed and code |
| low blood pressure | Yes | Less common |
| Application of pipes | Very suitable for | limited |
It can be seen that stationary mixers are the best choice for applications where the flow is continuous and does not require constant adjustment.
Finally
A static mixer is a simple and effective tool for uniformly mixing fluids in pipelines . The device utilizes a sophisticated internal component to direct fluid flows and achieve precise mixing without the use of motors, gears, or external forces. The use of a static mixer reduces operating costs, improves product quality , and shortens processing time .
Therefore, stationary mixers are now the ideal solution in many modern industries to replace complex and expensive conventional mixing systems.