Equipment Type
Fan
Equipment Name
Circulating Fan
Faults
Rotor misalignment
Early Detection of Circulating Fan Rotor Misalignment Fault
How Wisper CMS Ensured Continuous Operation at a Sludge Treatment Plant
Environmental Protection
Introduction
This case study demonstrates the diagnosis of a rotor misalignment fault in a circulating fan at a sludge treatment plant. Circulating fans are widely used for air circulation, ventilation, cooling, and gas conveyance across various industries. In a sludge treatment facility, the continuous and healthy operation of this equipment is crucial for maintaining process stability and environmental compliance.
Equipment Overview
The circulating fan is driven by an electric motor. When the motor starts, the fan blades begin to rotate, generating an airflow. This action creates a low-pressure area within the casing, which draws in surrounding air or gas. The fluid is then accelerated and pushed toward the fan's outlet by the continued rotation of the blades. The specific design and working principle of a circulating fan can vary depending on the application.
The Challenge
The continuous and critical nature of sludge treatment processes demands high reliability from core assets like the circulating fan. A mechanical fault, such as rotor misalignment, risks accelerating wear, leading to major equipment failure, costly repairs, and unplanned production downtime. Consequently, early and accurate fault detection is essential to justify intervention and ensure operational continuity.
Wisper Solution
After the fan was commissioned into the Wisper CMS, the health status of the fan was continuously monitored. On July 18, 2024, the system monitored a gradual decline in the diagnostic score for the rotor misalignment indicator at the motor drive end. The score dropped from a 'Healthy' state to an 'Available' state. The system immediately triggered a diagnostic report, advising the on-site team to closely monitor the equipment's running status and arrange for an inspection when appropriate.
Wisper CMS diagnostic report (Jul 18, 2024)
Timeline of Events
The outcome
The customer performed maintenance and replaced the coupling pad on January 17, 2025. After the equipment was restarted, the rotor misalignment diagnostic score at the motor drive end measurement point returned from the 'Available' status to a 'Healthy' status. The on-site inspection results were fully consistent with the diagnostic report, validating its accuracy and confirming the value of the AI system in enabling proactive maintenance.
understanding the root cause
Rotor misalignment can arise from multiple factors, including:
Poor coupling alignment.
Rotor flexibility and non-uniform mass distribution.
Uneven foundation settlement.
Thermal expansion of unit components causing bearing pedestal tilt and lateral movement.
Improper bearing pedestal assembly.
