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DMR: alternative for spray dryer

The spray dryer has a long history and is therefore a classical choice for many drying processes. However, there are also applications where another type of dryer is more suitable than a spray dryer – a ring dryer for example, or a flash mill dryer such as Hosokawa Micron's DMR.

Staying competitive in producing a dry product means also saving energy. Not surprisingly the best way to save energy cost is to minimize the amount of water to be evaporated. For this there are several possibilities by using mechanical dewatering before thermal drying, like for example centrifuging or filter pressing. Depending on many factors like particle size, particle size distribution, particle shape and partial solubility the rest moisture and physical appearance after dewatering can vary considerably.

The most common physical appearance after mechanical dewatering varies between high viscous slurry and (crumbly) filter cake. When a flash dryer is the most suitable dryer for your application, a further selection can be made for the type of flash dryer, like spray dryer, ring dryer or a DMR flash mill dryer.

Spray dryer vs. flash dryer

DMR flash mill dryer DMR flash mill dryer

In a spray dryer a low viscous slurry is pumped at the top of the spray tower and is atomized either by pressure, pressurized air or a mechanical disc. This can limit the possibilities on the feed consistency. In some cases it is even necessary to add water before it can be spray dried. Or in other words, the material is dewatered to a cake-like consistency, but in order to be able to spray the feed, the material has to be diluted with water.

Of course it is easy to recognize that this is the ultimate form of energy destruction. To get around this it is necessary to select a flash drying technology that is able to handle a feed material coming out of the mechanical dewatering step directly into the dryer. The DMR continuous flash mill dryer exactly fulfills this task.

Working principle DMR flash dryer

The wet material is fed through different specially designed feeding systems into the grinding and drying section of the dryer main body. The impact energy imparted by the grinding rotor disperses the wet material into very fine particles. A temperature controlled hot gas stream coming from the air heater is drawn by the exhaust fan through the main body and fluidizes the fine particles in the grinding chamber. This condition guarantees optimal heat exchange and instant evaporation of liquid.

The dried particles are conveyed with the gas stream to the top section of the dryer where a separator classifies the particles by size. Particles passing the classifier at the set cut point are conveyed with the exhaust air to a powder air separating systems like cyclone, cyclone filter or cyclone scrubbers for example.

A fluidized bed of product in the drying chamber insures a low level of adhesion of un-dried material at the inside wall of the drying chamber. By changing process parameters like the classifier speed, the outlet temperature, the moisture content and the particle size of the end product can be adjusted and controlled.

DMR flash dryer saves time and energy

Extensive tests have shown that the DMR continuous flash mill dryer can often replace existing spray drying processes and produce quality end products more efficiently. This is because the DMR is a multi-function unit capable of drying, grinding and classifying in one compact operation with close control of the product particle size and final moisture content. As the DMR can handle high solids content wet feed materials, significantly higher than for spray dryers, for example, evaporation levels are lower thus saving both time and energy!

Check your existing spray drying process now!

Test our DMR against a spray dryer for free! In our Test Centre we offer you the possibility of testing your product on our DMR, to compare the results with the spray drying process.

The first day of testing is free of charge!

SUSTAINABLE PROCESSING SYSTEMS

Hosokawa Micron B.V. is certified according to ISO 14001. Our certification covers all environmental themes of ISO 14001: air, soil, energy, waste, water, noise and hazardous substances. In addition, Hosawa Micron was awarded an EcoVadis Silver Medal for its sustainability achievements. EcoVadis determined that the company was among the top 7% of companies rated by EcoVadis in the special machinery industry.

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