Industrial agitators: understand how they work and their common failures

Agitadores industriais

Agitators are assets found in the production process of various industrial segments. Its role in industrial production is to mix or agitate products to make them homogeneous. The term mixture is used here to mean the random arrangement of two or more substances. Agitation, on the other hand, is characterized by the formation of a flow pattern in a liquid.

Learn more about how these assets work, their characteristics and failure modes in this article.

Application of industrial agitators

Agitators are used in various industrial segments, some of which are examples:

Pharmaceutical industry

They are used in tests and in the production of ophthalmic solutions, medicines, vaccines and cosmetic products such as creams or lotions, ointments, deodorants, lipsticks, varnishes, shampoos and toothpaste.

Petrochemical industry

In this sector, these assets are used in the production of oil, gas and their derivatives to guarantee process conditions and the correct physical properties of the fluids. In addition, due to the quantities of product involved, agitation processes play an important role in productivity and in reducing operating costs. This area includes operations such as homogenizing crude oil with water, controlling the flow of fluids to drilling wells or absorbing carbon dioxide from natural gas, suspending iodine in storage tanks or controlling pH.

Food industry

In this context, agitators make it possible to maintain constant properties in products, whether they are liquid, solid or gaseous. Moreover, its main objective is to homogenize the content. In the food sector, whether by manual or automated means, the mixture can be applied to the production of pasta, drinks, edible oils, flavor emulsions, among others. 

Water treatment industry

Here, agitators can be used in sewage treatment plants. The treatment process involves the processes of filtration, decantation and aeration, in which large rectangular tanks of considerable depth are used to promote mixing; they are also used in the production of drinking water and are present in operations to remove pathogens and contaminants, salt and dissolved solids in order to ensure quality in terms of taste, smell and appearance.

Types of industrial agitators and mixers

Although found in different processes, agitators can differ in their characteristics depending on the production process in which they are used. We will get to know some of the types of industrial agitators and mixers: 

Industrial Rotor Mixers

The most common types of agitators/mixers are those with an agitation rotor. In these assets, through the rotation of the rotor, made up of blades, the material is pushed and moved until the desired uniformity of the substances is achieved.

Turbine mixers 

This type of equipment is more robust than the previous ones and offers a wider variety of rotors, sealing systems and motor ranges. Therefore, they can be used in operations with high viscosity or tight tolerances and they are generally mounted vertically and can be aligned with the center of the container.

High Viscosity Mixers

High-viscosity mixers are characterized by working at low speeds and high twisting moments in order to rotate the larger impellers. In this way, these assets can tolerate more squeezing in relation to the walls of the tank. In addition, it is common to find anchor-shaped rotors in these mixers, which are effective in rapidly reducing the size, dispersion and reduction of powder particles and droplets, or helical profiles, which allow for greater efficiency, especially in terms of axial flow.

Industrial mixer and agitator components

These assets usually consist of three elements: an agitation shaft, agitation blades and an electric motor. In addition, an agitator can vary in the type of movement used for the uniformization of materials based on the impeller blade formats. Learn about some types of agitator blades according to the substance being handled.

Industrial agitator impeller blade shapes  

Straight blade: In this format, the agitator impeller blade is straight and can contain from 1 to 8 blades. Generally, agitators with this type of blade are used for mixing low-viscosity liquids.

Straight Blade Turbine: The impeller blade is fan-shaped, with 2 to 4 blades. Therefore, it is suitable for mixing in medium-viscosity liquids.

Propeller blade: The impeller blade has three blades arranged in a helical shape. It is used to mix low-viscosity liquids.

Anchor blade: The impeller blade is anchor-shaped, with 2 to 4 blades. It is suitable for mixing in high-viscosity liquids.

Ribbon blade: The impeller blade is ribbon-shaped, with 1 to 4 blades. It is therefore suitable for mixing in high-viscosity liquids

Common failures in industrial agitators

Industrial agitators and mixers, like the other assets present in any industrial process, need regular maintenance and periodic inspections to guarantee their functioning and operational longevity. In this equipment, the most common failure modes are associated with inefficient agitation or mixing, usually caused by a change in the agitator speed, a mismatch in the impeller position, or the agitator may be operating above its maximum load capacity, causing the substances not to be properly uniformed.

Industrial agitators can also suffer from leaks and spills, thus indicating faulty seals or even poor positioning of the containers. In addition, abnormal vibration signals in the agitators also require attention, as such phenomena could indicate an unbalanced impeller or unevenness in the asset. Other defects, such as the motor overheating, can also occur in agitators.

Success Case: identifying a failure in an industrial agitator motor

In this successful case involving the company Nexa and the Dynamox solution applied to fault detection in agitators, it was possible to prevent an unscheduled shutdown that could have affected the production flow.

The fault in question manifested itself in a flotation cell agitator. Flotation is the technique used to separate minerals in the mineral industry. Shortly, flotation is a physical-chemical process that enables minerals to be separated by means of their surface properties.

In this process, the minerals are placed in an aqueous solution with chemical reagents, which modify the properties of the minerals’ surfaces. In this way, air bubbles are injected into the solution, creating a foam that floats on the surface. Minerals with hydrophobic properties adhere to the air bubbles and are carried to the surface. However, the hydrophilic minerals remain at the bottom of the tank. Therefore, a flotation cell agitator is the asset that generates the necessary agitation to mix the contents and promote the attachment of the minerals to the bubbles.

How did the maintenance team diagnose the failure in the industrial agitator?

Nexa’s maintenance specialists noticed an A2 alert issued by the Dynamox platform. On checking the signal, they found a failure in the AS bearing and a gap in the motor cover.

industrial agitators - speed and peak-to-peak graphs

Then, the materials for maintenance were separated. In a short time, the material was already prepared, making the motor replacement process faster and safer.  

industrial agitators - graph

After the exchange, the vibration levels seen on the WEB Platform stabilized, showing that the asset was no longer at risk in its operation.

DynaPredict solution identifies defects in cell agitator motors using sensors.

Do you want to know more about how the Dynamox Solution works in continuous monitoring and automated failure detection in industrial assets?

Read more about the maintenance sector on our blog or ask one of our specialists.

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