Spray dryers are used for drying liquid and pasty products. According to the method of spraying, dryers are divided into disc and nozzle dryers. Due to the spraying of the product into small particles, these installations create a large area of contact of the product with hot air, while the drying process takes place within a few seconds, and the product is suspended during drying.
The drying process takes a minimum of time. When the product is sprayed, its contact area with hot air increases significantly, therefore, upon contact, up to 98% of moisture can be instantly evaporated. This method of dehydration is ideal for heat-sensitive materials, as it excludes overheating (burnout) of the main product.
- During drying, the product does not oxidize, retains color, smell, taste.
- The resulting product is completely ready for use, does not require additional grinding, has a homogeneous structure and a high rate of solubility. In most cases, the product is immediately ready for packaging.
- Possibility of temperature control over a wide range.
- The diameter and density of the granules, as well as the moisture level of the final product, can be adjusted by setting the conditions of the drying process.
- Possibility of obtaining a dry product, consisting of different components.
- The equipment is capable of operating in a continuous cycle.
Spray Dryer Applications
- Drying of bacterial preparations and protein-containing raw materials;
- Preparation of powdered mineral products;
- Obtaining powder forms of chemical synthesis products;
- Production of powder materials for special purposes;
- Obtaining powder carbon-containing products;
- Drying extracts of plant food raw materials.
Vertical pneumatic dryers (pipe-dryers) are distinguished by the relative simplicity of the device, rather low metal consumption and high process intensity. The short residence time of the particles in the drying zone (usually <1–2 s) allows the use of sufficiently high initial temperatures of the drying agent without the danger of overheating of the dried material. In terms of the specific indicator of the volume of investments per unit of evaporated moisture, pneumatic dryers are one of the most cost-effective units.
The pneumatic dryer is a vertical pipe with a length of 10 to 20 m, hot air and the product to be dried are supplied to the lower end of the pipe. The product particles move with the air flow to the upper end of the drying tube and are captured in cyclones or bag filters.
Pneumatic dryers are highly adaptable. In accordance with the customer's requirements, steam or natural gas combustion products can be used as a heat carrier. Due to a fairly simple design, pneumatic dryers are easily automated; the drying process on such dryers is highly reliable and safe.
Applications of the pneumatic tube dryer:
- Food products;
- Products of processing of vegetable raw materials;
- Chemical fertilizers;
- Organic and inorganic products.