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Molkerei Meggle Wasserburg GmbH & Co

Wasserburg am Inn, Germany

Balancing act in the spray tower

Spray dryers are complex systems. Protecting them against dust explosions requires extensive know-how. Dairy firm Meggle relies on the expertise of IEP Technologies, a company of the HOERBIGER Group.

[from HOERBIGER@MOTION June 2016 ]

In addition to the active ingredient, pharmaceutical tablets always contain excipients, which have no pharmacological effect. Lactose is used quite frequently as a filler and binding agent. Dairy firm Meggle is one of the world's leading manufacturer of pharmaceutical lactose. Most consumers associate herb butter, and other types of butter, with the company's trademark – the blue clover leaf – but pharmaceutical lactose has meanwhile also evolved into a product with a 60-year-long tradition.

Drawn-out process

Whey, which initially is still present in liquid form, passes through various process stages over as many as three days before the lactose powder is obtained. Some of the lactose is processed further in spray towers to obtain lactose that can be used to produce tablets without further processing. The whey is injected via spray nozzles from above as a fine mist into the extremely hot air of the dryer. This enormously increases the overall surface area of the liquid, drying the liquid. The drops are dry, and the lactose powder is separated from the air, in the bottom area of the tower.

Indispensable protection

At first glance, it would seem perplexing that lactose powder could trigger an explosion. Still, a spray dryer offers conditions that favor explosions: there is organic, extremely fine powder in a large volume of air and high temperatures. All that is missing for an explosion to occur is a third component – the spark.

Explosion protection is a balancing act. While safety is the top priority, faulty activations are also undesirable.

All-round protection

Meggle decided in favor of all-round protection of the tower using IEP Technologies' explosion suppression. The system consists of signal red suppressant storage cylinders, which are installed at various levels around the spray dryer, but also on other power units. The pressure sensors are configured to respond to a rise in pressure typical of an explosion. If an explosion looms, the sensors detect this increase within milliseconds and respond in a fraction of a second by extinguishing the explosion. The explosion protection concepts made by IEP Technologies, which became part of HOERBIGER in 2015, can be found in approximately 80 percent of all current spray driers.