Milk powder is produced in two stages, the first being evaporation and the second drying. In the first stage the total solids content of the milk is raised from the natural level of 9-12 % to about 50 % before the product is completely dried in a spray dryer to a total solids content of about 97 %.

In the evaporation stage ABB's MVR (Mechanical Vapour Recompression) technology generally considerably reduces energy consumption and increases flexiblity in product range and production capacity characteristics. In the second drying stage fans with frequency converters are used to adapt performance to process requirements.

The milk flows through the pipes of the heat exchangers (1). The hot steam surrounding the pipes makes the water evaporate from the milk. The evaporated water is separated from the milk in the separator (2). The steam is compressed by the fan (3,4) and is fed back to the heat exchangers (1).


Steam fan in milk powder process.

Solved Problem

• Changing parameters during the production run, for example variation in total feed solids content, fouling of the heat transfer surface
• Complicated cleaning of the evaporation plant
• Excessive energy consumption

• MVR Fan: 20 400 kg/h, 3200 rpm
  
• Motor: 315 kW, 2980 rpm, 690 V
  
• Frequency Converter: 400 kVA, 690 V

• Steady plant performance throughout the whole production run
  
• Improved quality due to accurate speed control
  
• Higher productivity because of extended equipment service level
  
• Reduced energy consumption with optimum fan motor speed and soft start function