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Spray drying towers

Treatment of the intake air for spray drying towers and pneumatic transfer of dairy products or processing aids by DESSICA systems allows for significant productivity gains and energy savings through control of the humidity.

The functioning of a spray drying tower is subject to seasonal variations. In particular, the mixing ratio (absolute humidity) of the upstream air is a determining factor in the capacity of the dry tower. In the summer, when this ratio is high, the capacity is reduced, while in the winter, when this ratio is lower, the capacity is greater. These variations complicate operation of the tower, with increased risks of production halts.

Control the humidity of the air upstream of spray drying towers to achieve constant and stable intake conditions with DESSICA systems.

The spray drying process: a superior answer to the food industry’s needs

Whilst the spray drying process is used in both pharmaceutical and industrial applications, it’s probably the agri-food business that is the most regular employer of this approach. Spray drying for dairy products in the shape of milk powder was an extremely common use of this process, which requires a special chamber called a dehumidifier drying tower. Whole-fat milk, skimmed milk, buttermilk and whey can all be processed in this way. Nowadays, milk powder is often created from skimmed milk, especially when creating recombined dairy products. This powder is also used for feeding infants.

Other food products that frequently receive the spray drying treatment include coffee, eggs, tea, cereals, a range of spices, stevia, vitamins, animal feed, colourings, starch and starch derivatives and even blood!

Dehumidifier for food drying process

All companies using a spray drying tower are facing challenges. Atomization drying towers are subject to external & seasonal variations. The mixing ratio (absolute humidity) of the upstream air is a determining element in the capacity of the tower. In summer, when this ratio is high, the capacity decreases, whereas in winter, this ratio is lower, the capacity is higher. These variations make it more difficult to operate the tower with a high risk of production disruption.

Dessica ™ Systems’ control the humidity of the upstream air of the spray drying towers to obtain constant and stable intake conditions.

Drying process is an old method to safe foodstuffs, it is use for fruits and vegetables, and also with various technics with spray drying process, fluidized bed dryers and rotary dryers. In all this transformation process into powders, purees and flakes, the atmosphere must be control to limit the spreading of humidity. The dry air avoids the risk of clogging and caking.

The spray drying process depend on seasonal variations. DESSICA provide dry air upstream spray drying process to avoid sticking product and improve end-product quality.

Sterile air dehumidification unit is a hygienic system, specially designed to meet the requirements of users in the food industry.

Dry air in spray drying process

Dry air supply plays a major role in spray drying process working. The climatic variations in summer and winter disrupt the spray drying functioning. With standardized settings, the product flow injects into the tower increase thus the productivity growth. The dry air supply from a dehumidifier avoids clogging and caking of the product in spray drying tower.

This process is also use in pharmaceutical industry for plant extracts, body care and fine chemicals manufacturing.

Air treatment in spray drying process and pneumatics transfers for dairy products or additive by DESSICA systems permit to master hygrometry, profit productivity and energy consumption.

Dry air for fluidized beds

For the industrial drying processes with spray drying tower and fluidized bed systems (milk powder, coffee, yeast for example), hygiene and energy consumption are major issues. The DESSICA solutions significantly optimize theses product drying processes, such as spray drying towers and fluidized beds systems.

The fluidized beds are used in several applications in food processing, dairy, chemical and pharmaceutical industries. They are all use for drying or cooling of particles (powders, agglomerates), sugared pills or granulates from fin powders. The fluidized beds and pneumatics conveying are subject to advanced conditions and technologies. Fluidized bed dryers are recommended in the food industry for gentle and uniform drying, and to preserve the quality of chemical molecules and ingredients. The air supply in the fluidized beds dries the wet bulk products to a powder. The fluidized bed drying and powdery product transport processes also use dry air.

DESSICA supply provide the driest air possible upstream of the compressor or fluidized bed. This process reduces the risk of clogging and the caking of the product in these processes.

Low humidity for pneumatics conveying or bulk storage

Some powdered products are very hygroscopic. For pneumatics transport or bulk storage in silo some reactions appear: caking or clogging. These reactions are due to absorption of moisture by the powders and the high-level humidity. The DESSICA’s systems permit a reduce the dew point of air thus avoiding moisture adsorption and insure the fluidity of the product.

To avoid moisture adsorption, the dry powder must be in contact with dry air. The conveying systems must be equipped with dehumidifier to maintain rapid flow of raw materials and exclude the risk of caking and clogging.

Advantages and benefits of the spray drying technology

the risks of a production halt due to climatic variations and products sticking to the walls are greatly reduced. Operation of the drying tower is made easier by reducing changes in settings;
the capacity of the drying tower is constant and maximised and the residual moisture in the product is stabilised throughout the year by climatic conditions without significant variation in all seasons ;
energy consumption is optimised: as drying by adsorption is an exothermic phenomenon, it increases the temperature of the dry air, substantially limiting the energy input to the system.
reduce the dew point of the air
preventing absorption of moisture
guaranteeing the fluidity of the product
reduce the risk of clogging and caking
uniform premium quality
maintain a constant humidity level for process air
control and optimize production
reduce maintenance times for process equipment
lower energy consumption

The quality of our products, the efficiency of our installation and the impact on your work processes will be almost immediate.

Spray drying for dairy products: when humidity control is key

Drying foodstuffs has long been known to be an excellent way of preserving food. Dairy products first received this treatment way back in the 19th century and today huge quantities of milk, buttermilk and whey are dried to produced powdered milk. The advantages to this approach for the dairy processing industry are numerous and include major reductions in product weight (and thus reductions in the cost of transportation) and a far longer shelf life. The most common way of drying dairy products is the spray drying process.

Spray drying for dairy products also presents some very specific challenges. As is the case with the wider farming industry, changes in local weather conditions and seasonal variations must be adapted to in order to deliver the best possible outcomes in the spray drying dairy industry. With spray drying, fluctuating humidity in particular is an issue, as this can damage product quality and consistency.

The role of dehumidifiers in the spray drying process

We’ve established that in the spray drying of milk powder – and indeed other foodstuffs – humidity control matters. How exactly does a desiccant air dryer system help tackle this problem? Well, by controlling the humidity of the air entering the drying chamber or tower. In other words, by lowering humidity to a consistent, steady level, the dried air can be heated to higher temperatures than would be possible if it contained more moisture. If the air’s humidity is predictable, the way in which it will interact with the food substances in the tower will also be more predictable.

All this adds up to multiple benefits for the spray drying dairy industry. Production levels will be consistent, regardless of what the weather is like outside or the time of year. Products are less likely to stick to the walls of the drying tower, meaning production disruption is minimized. Tower drying capacities are increased, thanks to the dryer input air. And less energy is required for the same end result!

Milk powder technology: evaporation and spray drying

One of the most common processes in the modern dairy industry is the production of powdered milk, using whole milk, skimmed milk, buttermilk or whey. Sometimes this is aimed at the infant formula market, but powdered milk is also used by adults and is widely appreciated for the advantages that it can offer in terms of greater longevity, easier storage and cheaper transportation.

The process of milk powder evaporation is only the first stage in the journey from liquid to powdered milk. Most of the water in the milk (up to 85%) is boiled off at low pressure and low temperature before we even start the spray drying stage. Once the milk powder technology evaporation method has been applied, the resultant milk concentrate is atomized from the evaporator into the drying chamber or tower. The spray is projected into a flow of hot air, further reducing the water content of the milk.

Spray drying and the part played by dehumidification technology

The process of spray drying has to face up to an ever-present challenge, changing weather conditions, more specifically, changing levels of atmospheric humidity.

These variations can make it hard to deliver consistent results with a spray drying tower. The best way of responding to this issue is to use desiccant silica gel rotors in tandem with the milk powder technology employed to remove water from milk. These rotors or wheels help maintain a constant level of humidity, removing water from the air by means of a double air flow through a large wheel mostly composed of active silica gel, which is extremely effective at adsorbing moisture. The first air flow dries the air, the second, back through the wheel, helps dry the silica gel out again. This dryer, colder air is heated up and blown through the drying tower to complete the process begun by the milk powder evaporation phase.

Implementation of milk powder technology evaporation

Avoid the risk of clogging or caking in spray drying tower
Increase the flow rate of product injected into the tower to increase production
The installation of the DIA system has enabled NUTRIBIO to increase its production volume by 35 to 45% per turn. Return on investment is less than 1 year !

The vegetable and fruit technology evaporation system by Dessica Dryair

A huge challenge facing both the fruit and vegetable production sectors is the impact of high temperatures upon produce during the immediate post-harvesting phase. Unless these kinds of foodstuffs can be transferred to and stored in a cool environment quickly, they risk deterioration with regard to multiple physical characteristics (e.g. colour, texture) which can reduce their market value. There are also obvious implications regarding shelf life. Traditionally, people have used various kinds of refrigeration techniques, but these pose several problems – this is where a spray drying tower for vegetables or fruits can work wonders!

Using a spray drying tower to create fruit powders

The use of dry air in a spray drying tower is an excellent way for agri-business to create new products with a far longer shelf-life than fresh produce. The spray drying tower that is used to process either fruit juice or fruit mash and turn it into fruit powders is one of the key components of Dessica’s vegetable and fruit technology evaporation system. A huge range of different fruit powders can be created using this approach. Pineapple, orange, guava, banana, mango, watermelon and tomato are just some of the fruits commonly treated in this way.

Spray drying is suitable for vegetables too!

It’s not just fruit that can be turned into a powder. Plenty of vegetables are suited to this approach as well. Staples such as potatoes are often spray-dried to produce ‘instant’ mashed potato products – this can be an excellent way for farmers to deal with a large surplus. The vegetable and fruit technology evaporation system designed by Dessica incorporates a spray drying tower, which is capable of dealing with the very large quantities that can sometimes be involved in these operations. Spray-dried vegetable powders are typically used in soups, stock cubes, sauces, flavours and as dietary supplements, to name just a few applications. Vegetables often used include beetroot, garlic, onion, cauliflower and cucumber.