Precision Airflow Control for Barley Steeps
Background
Process Instrument Solutions was approached to improve air circulation control within several barley steeps used in the malting process. These steeps facilitate controlled germination, where raw barley moisture content is increased to initiate germination and produce chitting (rootlets). This stage is critical for breaking down the cell wall and developing the enzymes required for brewing.
Airflow within the steeps is regulated via louvres that open and close to maintain a balanced temperature, ideally between 15–16°C. While the louvre system and Kinetrol pneumatic actuators were already in place, the control and feedback mechanisms required upgrading to ensure reliable and precise operation.
Challenge
The existing system lacked the accuracy and reliability needed to consistently maintain tight temperature control within the steeping process.
Precise positioning of the louvres is essential to balance airflow and temperature, which is directly influenced by a centrally located temperature sensor within the barley bed. Without accurate actuator feedback and control, maintaining optimal conditions for germination becomes difficult, potentially impacting product quality and process efficiency.
The customer required a robust, repeatable, and low-maintenance solution that could integrate with the existing air handling system and plant SCADA controls.
Solution
Process Instrument Solutions designed, built, and installed new control panels and upgraded the actuation control system using Siemens SIPART PS2 positioners, complemented by remote position transducers.
Custom mounting brackets were engineered to house non-contact magnetic coupling sensors, which detect position through changes in resistance proportional to actuator movement. This provided highly accurate and wear-free position feedback for the louvres.
The system operates using a central temperature input from within the barley bed, with outputs communicated via the plant SCADA system. A 4–20 mA feedback signal from the positioners ensures closed-loop control, confirming that commanded louvre movements are completed accurately.
Additional components, including Siemens air filter regulators, were installed to ensure consistent and reliable pneumatic supply. The system utilised split-ranging control to deliver precise and repeatable positioning across multiple actuators.
This approach has also been extended to the kiln system, where a louvre has been fitted with a Festo piston potentiometer, applying the same proven control principles.
Result
The upgraded control system has delivered highly precise and stable air circulation within the steeps, ensuring consistent temperature control throughout the germination process.
Since commissioning, the system has operated continuously for over five years without any reported issues, demonstrating exceptional reliability and minimal maintenance requirements.
The improved accuracy and repeatability of louvre positioning have enhanced process stability, supporting optimal germination conditions and ultimately contributing to consistent product quality for brewing.
The solution has provided a long-term, dependable upgrade to the existing infrastructure, maximising performance while utilising and enhancing the customer’s installed equipment.
