Why good humidity control matters in modern spray drying

Food, pharmaceutical, and other production processes dealing with powder production, utilize spray drying to ensure product quality and consistency. But spray drying requires stable humidity conditions to work at its premium.

Modern spray drying is a rather complex process. Strict product specifications must be dealt with, just as variations in raw materials and on top of that, ambient weather conditions. Uncontrolled humidity and temperature can cause problems during the drying process.

Traditional spray dryers maintain constant conditions, regardless of ambient weather conditions and humidity. This will impact dryer performance and the product quality negatively, as air humidity fluctuates. Dehumidification will rectify this issue.

A desiccant dehumidifier will reduce the moisture in the air, ensuring consistent air conditions irrespective of weather changes. On humid days, the dehumidifier works intensively, but will slow down during drier periods to save energy.

And the product yield will improve: In the case of infant formulas, dehumidification is impactful. Lowering ambient humidity from 10 to 2g/kg can increase milk powder capacity by 20% and infant formula capacity by 40%.

Excessive ambient air humidity, presents some obvious risks to powder production:

• Clumping and blockages: As powders and granules have a natural tendency to form lumps and clumps in humid environments – especially prevalent in food and pharmaceutical processing.
• Mold, fungi, and bacterial growth of all kinds can easily occur where the relative humidity is high. They can cause major damage to products and could be a health risk to employees.
• Condensation can result in pooling on surfaces where powders may get stuck and clump inside the machinery and/or drying chambers.
• Corrosion of the spray drying equipment can reduce its efficiency and shorten its service life, driving up service and maintenance costs.

In addition, after the products have dried, post-cooling often is needed before packaging. Traditionally, cold water has been used to ensure efficient post-cooling, but it is important that the dry powder does not regain water in the cooling process, as hygroscopic powders may form lumps and cause blockage. Worst case, moisture may even cause bacteria to spread in the powder can at this latest stage of the production chain. Using desiccant dehumidification in the post-cooling process, the dehumidifiers can achieve lower air humidity and prevent powders from regaining moisture during cooling.

Good humidity control is the key to an energy-efficient spray-drying process, minimized risk of sticking, lumping, and bacteria and thereby a better yield, and most importantly, good humidity control is the key to a high, stable, and predictable product quality.

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