Stella Artois Belgium’s largest brewery produces light beer which must be stored in large vessels at low temperature for several weeks before bottling.
At Leuven, several storage vessels protrude through the wall into a corridor and are cooled to +2°C by air chilled to -2°C and circulated through the storage buildings. In the cooled building, with surface temperatures at +2°C the air can contain only 4g moisture/kg air, but in summertime, due to its higher temperature ambient air can hold more than 15g moisture/kg of air. Unless the air conditioning plant is capable of removing sufficient moisture, condensation cannot be avoided.
Condensation and high humidity are ideal conditions for mould and bacterial growth, and at Leuven all corridors were washed with hot water and detergents once or twice a week to prevent this. These cleaning regimes exaggerate the problem by increasing the amount of water needing to be removed.
Regular decoration to the structure was required due to the deterioration experienced as a result of continual high humidity and condensation.
The traditional means of dealing with condensation involved ventilation air to carry away the evaporated moisture. However, unless the air being introduced has a moisture content, with a dew point well below the temperature of the storage vessels (occasionally occurring during winter) this is a totally unpredictable approach.
Munters installed two 1200m3/hr dehumidifiers with the drying time reduced to 1 day after washdown, and the corridor maintained at 40% relative humidity (RH) between 5-10°C, the result being the total prevention of condensation.
Stella Artois decided to install a further two Munters systems each handling 15000m3/hr maintain a constant 40% RH at 10°C to speed up drying after washdown. The efficient drying of the corridors and low humidity level, now virtually eliminates the risk of microbiological growth and maintenance costs have been reduced.
As the humidity level dries standing water in one day, the previous maintenance requirements have been dramatically reduced. Redecoration is no longer a frequent necessity. As the lower moisture level in the corridors produces less moisture migration and infiltration, frosting on the evaporators has reduced and less defrost energy is needed.