Background

The customer required an advanced system to circulate chilled water, maintaining specific product temperatures across various processes while minimizing electrical energy consumption for pump motor operation. The chilled water is stored in an Ice Bank Tank (IBT) and must be circulated through a 150 mm diameter pipe to various Plate Heat Exchangers (PHE) for chilling milk to 4°C. The system must meet a peak chilled water requirement of 150,000 liters per hour (LPH).

System Description

The previous system operated with two 10 HP pumps and one 15 HP pump, maintaining a pressure of 6 Kg/cm². This setup had several limitations:

• Manual Control: All motors were manually controlled, leading to significant energy loss.
• Limited Flow Control: Inadequate feedback on flow and temperature, resulting in inefficient operation.
• Energy Loss During Off-Peak Times: Excess energy consumption due to lack of automated control.

Solution:

The new system introduces smart and intelligent control with a touch screen-based user interface. It includes a total of six 7.5 HP pumps. The pumps are managed using a combination of inverter drives and commercial drives, utilizing an algorithm built into the Mitsubishi Electric FR-A800 Series VFD, which employs two of the four available PID control loops.

System Configuration:

• Motor Control: The system combines inverter-driven motors, commercially-driven motors, and auxiliary motors.
• Inverter-Driven Motor: Always fixed and operational.
• Commercially-Driven Motors: Added sequentially to the control loop when the required discharge flow rate exceeds the capacity of the inverter-driven motor alone.

Benefits:

• Energy Efficiency: The new system reduces current demand to approximately 70% of the previous system, significantly lowering power consumption and energy charges.
• Consistent Product Quality: By maintaining a constant temperature, the system ensures consistent product quality.
• Environmental Commitment: This energy-efficient solution underscores the customer’s commitment to sustainability and future generations.

Detailed Benefits

1. Energy Efficiency:
   • The smart control system optimizes pump operation, reducing energy waste.
   • The use of Mitsubishi Electric FR-A800 Series VFDs allows for variable motor speeds, matching the system’s flow rate and pressure requirements more precisely than fixed-speed pumps.
2. Consistent Product Quality:
   • Maintaining the chilled water at a consistent 4°C ensures that the product quality is not compromised.
   • The system’s precise temperature control supports consistent output across all processes.
3. Environmental Impact:
   • Lower energy consumption reduces the overall carbon footprint.
   • The system demonstrates a proactive approach to energy conservation, aligning with global sustainability goals.
4. Operational Efficiency:
   • The touch screen-based HMI provides an intuitive interface for operators, enhancing usability and reducing the potential for human error.
   • Automated control reduces the need for manual intervention, allowing for more efficient and reliable operations.
5. Cost Savings:
   • Reduced energy consumption translates directly into lower operating costs.
   • Improved operational efficiency and consistent product quality minimize waste and potential losses.

By implementing this advanced VFD Multi-Pump Control System, the customer achieves significant energy savings, improved product quality, and a robust demonstration of environmental stewardship. This solution ensures efficient, reliable, and sustainable operations for the chilled water circulation system.