Working principle

Two fluid atomizer (air flow atomizer) generates kinetic energy through the high-speed flow of compressed air or steam, cutting and tearing liquid materials into tiny droplets. The core is the interaction between gas-liquid two-phase flow: the liquid flows out of the central pipeline and collides violently with the surrounding high-speed airflow (usually at a speed of 200-300 m/s), forming a fine atomization effect. This atomization method relies on the kinetic energy of the gas and has low requirements for the fluidity of the liquid itself, making it suitable for handling materials with high viscosity or particles.

Centrifugal atomizers rely on mechanical centrifugal force to achieve atomization. The liquid is transported to a high-speed rotating atomizing disc (with a speed of 10000-50000 rpm), and under the action of centrifugal force, the liquid is ejected from the edge of the atomizing disc, forming a uniform liquid film. The liquid film breaks into droplets due to surface tension when it separates from the atomizing disc. This method is sensitive to the viscosity of the material, but can generate particles with uniform particle size distribution.

Structure and Composition

The structure of the two fluid atomizer is relatively simple, mainly composed of a nozzle (including liquid and gas channels), a compressed air supply system, and a pressure regulating device. Its advantage lies in the fact that it does not require complex mechanical transmission components, but requires a stable and clean gas source (such as oil-free compressed air or steam), and consumes a large amount of gas.

The core of a centrifugal atomizer is a high-speed rotating atomizing disc and a driving motor, which require high-precision bearings, lubrication systems, and dynamic balancing devices to ensure stable operation. The mechanical structure is complex and the maintenance cost is high, but there is no need for additional air supply during operation, relying only on electrical energy to drive.

Droplet characteristics and drying effect

1. Droplet size:

-The droplets generated by the two fluid atomizer are finer (10-100 μ m), suitable for producing ultrafine powders or nanomaterials.   

-Centrifugal atomizers have larger droplets (30-200 μ m), uniform particle distribution, and better flowability, and are commonly used in the food or chemical industries.   

2. Material adaptability:

-The two fluid atomizer can handle complex materials with high viscosity (>500 mPa · s), fiber or solid content (such as traditional Chinese medicine extracts and biological fermentation broths).   

-Centrifugal atomizers are sensitive to material viscosity and are typically suitable for homogeneous liquids with low to medium viscosity (<300 mPa · s), such as milk and dye solutions.   

3. Drying uniformity:

-Centrifugal atomizers have more stable particle size and flowability after drying due to the uniform droplet size.  

-If the gas-liquid ratio of the two fluid atomizer is not properly controlled, problems such as droplet aggregation or uneven particle size distribution may occur.

Performance and energy consumption

1. Energy consumption:

-Two fluid atomizers require continuous consumption of compressed air or steam, resulting in high energy consumption, especially in large-scale production where costs are significant.   

-Centrifugal atomizers rely on motor drive, with relatively low energy consumption and better long-term economic efficiency.   

2. Noise and maintenance:

-The two fluid atomizer generates significant noise (up to 85 dB or more) due to high-speed airflow, and requires regular cleaning of the nozzle to prevent clogging.   

-Centrifugal atomizers have lower noise levels (about 70-75 dB), but require frequent maintenance of bearings and lubrication systems, and the cost of replacing the atomizing disc is higher.   

3. Production scale:

-Two fluid atomizers are suitable for flexible production of small batch, high value-added products such as pharmaceuticals and biologics.   

-Centrifugal atomizers are suitable for continuous large-scale production (such as milk powder and chemical raw materials), with a production capacity of several tons/hour.

Applicable scenarios

1. Typical applications of two fluid atomizers:

-Pharmaceutical industry: Low temperature drying of thermosensitive drugs (such as enzyme preparations, probiotics) to retain active ingredients.   

-Nanomaterials: Preparation of ultrafine metal oxides and catalyst powders.   

-Complex materials: drying of high viscosity traditional Chinese medicine extracts and suspensions containing particles.   

2. Typical applications of centrifugal atomizers:

-Food industry: drying of bulk products such as milk powder, coffee powder, starch, etc.   

-Chemical industry: Production of inorganic salts (such as sodium sulfate, calcium chloride) and ceramic powders.   

-Conventional materials: continuous drying of low viscosity solution, lotion or slurry.

Summary of advantages and disadvantages

1. Two fluid atomizer

-Advantages:

-Strong adaptability, capable of handling complex materials with high viscosity and solid content;   

-Flexible particle size adjustment (by adjusting the gas-liquid ratio);   

-Suitable for small batch, high value-added production.   

-Disadvantages:

-High energy consumption, relying on stable gas sources;   

-High noise and operating costs;   

-The droplet distribution is wide and requires precise control of parameters.   

2. Centrifugal atomizer

-Advantages:

-Uniform particles and good fluidity;   

-Low energy consumption, suitable for large-scale production;   

-No additional gas source required, the system is simple.   

-Disadvantages:

-Poor adaptability to high viscosity materials;   

-The mechanical structure is complex and the maintenance cost is high;   

-Replacing the atomizing disc or adjusting the speed takes time.

 Selection suggestions

-Prioritize the use of two fluid atomizers:

When the material has high viscosity, contains particles, or requires ultrafine powder (such as pharmaceuticals, nanomaterials), or when the production scale is small and the product type needs to be frequently changed.   

-Priority should be given to centrifugal atomizers:

When dealing with low viscosity homogeneous liquids, pursuing high production capacity and particle uniformity (such as food and chemical bulk products), or when long-term operation requires cost control.

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