Spray drying is a well-established method of converting liquids into powders. However, it has limitations when it comes to precisely controlling certain product properties, such as particle size, solubility, and flowability. The solution is fluidized bed technology. It complements spray drying perfectly, making powder production more flexible, and significantly increasing efficiency for products that perform exactly as intended.
In spray drying, a liquid – typically a solution or suspension – is sprayed into a spray dryer. The liquid quickly evaporates when exposed to hot air, leaving behind a fine powder. This product often causes problems in many applications because it is very fine and dusty, which makes it difficult to handle. Additionally, its poor flowability can make further processing challenging. Furthermore, options for precisely adjusting product parameters are limited, especially when controlling particle size and solubility. However, precisely adjusting these properties is critical for the powder’s processability and the quality of the final product.
When every property counts: Powders for various industries
What happens when spray drying and fluidized bed technology are combined? Spray-drying agglomeration. In other words: it is a true power duo! Here is how it works:
Step 1: Spray drying
The process begins with a liquid solution or suspension that is atomized in a spray dryer. The droplets dry immediately in the hot air, leaving behind a fine, dry powder.
Step 2: Agglomeration in the fluidized bed
The powder from the spray dryer is transferred to a fluidized bed dryer. There, it is fluidized with air. Through targeted liquid spraying, the fine particles combine to form larger, loose agglomerates. This process makes the particles more stable, more free-flowing, and less dusty, ensuring the powder can be handled easily and safely. Solubility also improves significantly. This is particularly valuable in the food industry because it eliminates the need for additional additives in the formulations.
What is fluidized bed technology?
But what exactly is it? Simply put, in a fluidized bed, solid particles are kept suspended by an airflow. This constant movement creates optimal conditions for heat and mass transfer. Unlike traditional spray drying, liquids in a fluidized bed do not evaporate freely into the surrounding space; rather, they dry directly on the surface of existing solid particles. By modifying specific physical properties, this process yields products with defined characteristics.
In a fluidized bed, solid particles are fully accessible to the drying medium and applied liquid. Consequently, this process is extremely energy-efficient and gentle on the material.
Spray-drying agglomeration: How does fluidized bed technology complement spray drying?
What happens when spray drying and fluidized bed technology are combined? Spray-drying agglomeration. In other words: it is a true power duo! Here is how it works:
Step 1: Spray drying
The process begins with a liquid solution or suspension that is atomized in a spray dryer. The droplets dry immediately in the hot air, leaving behind a fine, dry powder.
Step 2: Agglomeration in the fluidized bed
The powder from the spray dryer is transferred to a fluidized bed dryer. There, it is fluidized with air. Through targeted liquid spraying, the fine particles combine to form larger, loose agglomerates. This process makes the particles more stable, more free-flowing, and less dusty, ensuring the powder can be handled easily and safely. Solubility also improves significantly. This is particularly valuable in the food industry because it eliminates the need for additional additives in the formulations.
Spray granulation: How can fluidized bed technology replace spray drying?
Fluidized bed technology offers several ways to influence product properties specifically. In addition to spray-drying agglomeration, spray granulation is widely used in various industries. This process is of particular interest to companies without their own spray dryers, as it can serve as a replacement technology. The result is compact, round, homogeneous granules with a high bulk density that are dust-free, making them easier to handle and process. The process is as follows:
- In spray granulation, slurries are atomized and hit the granulation seeds.
- The liquid evaporates, and the solid builds up on the granulation seed, forming a coating.
- This process repeats continuously in the fluidized bed, resulting in compact, uniform granules with a layered structure.
- Parameters such as particle size, residual moisture, and solids content can be precisely controlled in spray granulation.
Spray granulation is frequently used for products such as flavorings, proteins, enzymes, detergents, extracts, baby food, fertilizers, and pesticides.
Greater productivity and lower costs: Advantages of these processes
Using fluidized bed technology instead of or in addition to spray drying offers several advantages:
- Improved processability: In the fluidized bed, dust content decreases, and mixtures can be stabilized during processing. Additionally, solubility and compressibility are improved, which is a clear advantage for the subsequent pelleting or tableting of the powder.
- Gentle processing: Low product temperatures during processing help protect heat-sensitive ingredients and preserve enzyme activity, for example.
- Quality improvement: Masking odors and flavors improves product characteristics. In addition, hygroscopicity – that is, the powder’s ability to absorb moisture from the air – is reduced, thereby extending the products’ shelf life.
- Precise control of particle properties: Particle size distribution, flowability, and bulk density can be precisely adjusted, opening up new product possibilities.
- Capacity increase: Throughput rates can be increased by up to 60% with spray-drying agglomeration compared to using a spray dryer alone without the need for an additional spray tower.
- Cost savings: Short process times and the integration of multiple process steps reduce operating and investment costs.
Conclusion: Efficient processes and improved products
Spray-drying agglomeration, which combines spray drying and fluidized bed technology, as well as spray granulation, offer significant advantages in the production of powders and granules. These processes enable more efficient operations and the production of high-quality products, particularly in the food, pharmaceutical, and chemical industries.
With our fluidized bed plants Conti-FB, Amandus Kahl offers a solution that enables flexible expansion of production capacities. Thanks to their compact design, our fluidized bed plants can be easily integrated into existing drying lines. Batch-FB plants are also available for smaller batches, such as those used in research and development. Our larger Batch-FB plants are well-established for production scale use, as they enable very precise batch separation, for example. The virtually unlimited possibilities for varying product and process parameters – including temperature, flow, and spray settings – allow for precise achievement of desired product properties. Those who rely on this technology are well-equipped to meet future challenges!
