Germination utility requirements and germination process sequence

Pneumatic Malting Process

  • Involves the passage of tempered humidified air through a germinating grain bed.

Importance of Airflow

  • Airflow controls grain temperature, supplies oxygen, and removes carbon dioxide.

  • A 400-ton batch of barley includes approximately 12 billion kernels, demanding significant airflow for aerobic respiration.

  • Airflow needed during germination is at least 6 times that required for carbon dioxide removal during steeping.

Air Supply Management

  • The temperature of supply air is managed through heating and cooling methods applied to water in the humidification spray deck.

  • Variable speed fans adjust the airflow rate through the grain for effective temperature control.

Utility Requirements

  • Proper management of heating and cooling is crucial in malt plants operating year-round under diverse ambient conditions.

  • Germination temperature must consistently range from 63 to 72 degrees Fahrenheit.

  • High humidity for germination air is maintained based on the temperature of the air.

Utilization of Return Air

  • Return air plays a significant role in energy management within the malt plant, being the warmest air in winter and the coolest in summer.

  • Strategic blending of return air with fresh air is preferred to the use of 100% fresh air during germination.

  • Return air use is limited by the necessity to control carbon dioxide levels, permitting up to 70% usage during extreme conditions.

Germination Process

  • The grain bed must be adequately watered using a spray bar during turning runs to counteract drying effects of airflow.

  • The process involves consistent germination vessel loading and leveling.

Vessel Design and Loading

  • Circular germination vessels allow for quicker loading and leveling than rectangular ones.

  • Circular design facilitates single-path loading, while rectangular design requires multiple steps to achieve a distributed and leveled bed.

Distribution and Evenness

  • Evenness in grain bed, both end-to-end and side-to-side, is critical for uniform airflow once positive pressure is established.

  • Proper grain bed resistance must be managed to ensure air is evenly distributed during germination.

Germination Phase

  • Takes place over 4 to 5 days, supporting aerobic respiration through temperature control and airflow.

  • Careful turning of the grain bed promotes uniform airflow, and watering is carried out as needed.

Conclusion of Germination

  • Upon reaching desired conditions, the germinated barley, now termed green malt, is quickly transferred to the kiln for further processing.