Case Study: Cement Silo Remote Inventory Monitoring

Remote Silo Inventory Monitoring with Ultrasonic Level Sensors

Challenge

A cement manufacturing facility with seven silos ranging from 26 to 30 feet in height faced significant challenges in accurately monitoring inventory. The silos housed three types of materials: cement powder, slag, and a blend.

The primary difficulty was the continuous heavy dust caused by the aeration process via compressors. This dust interfered with conventional contact and non-contact, through-air level devices, rendering them unreliable and maintenance intensive. The customer required a maintenance-free solution that could monitor the inventory levels in the silos reliably with the added ability to access data remotely.

Solution

ABM’s remote tank level monitoring package was the chosen solution. The package included:

Implementation

Seven sensors were installed on top of the silos using ball aimers, which facilitated precise aiming at the discharge hole to enhance sensor performance.

Key Features of the Remote Ultrasonic Level Sensors:

  • Automatic Power and Gain Adjustments: The sensors adapt continuously to the environment, ensuring accurate readings despite changing dust conditions and material surface changes. Figure 1 and Figure 2 show the sensor receiving the target echo from the material at a steep angle of repose after filling and while the silo is emptying.
  • Maintenance-Free Operation: The ultrasonic transducer’s highly active driver maintains a clean sensor face, crucial for reliable operation in environments with dust and condensation. With self-cleaning operation, maintenance is eliminated.
  • Remote Two-Way Communication: Built-in cellular modems allow real-time data transmission for remote monitoring by the customer and enables full 24/7 remote support from ABM engineers.

Figure 1: Echo profile after silo fill shows the target echo received with material at a steep angle of repose.

Figure 2: Echo profile during silo emptying illustrates the target echo with material at a steep angle of repose.

Actions Taken with Remote Active Control:

As part of the package, the customer received full remote support from experienced ABM engineers for the challenging application.

  • Set-Up and Calibration: Engineers remotely set up and calibrated the sensors for high and low-level set points.
  • Custom Filters: After monitoring the complete emptying and filling processes, the engineers applied custom filters to optimize the sensors’ performance for the environment. Filters included the ‘level jump filter’ to manage rapid material drops (rat holes) and another filter to suppress false echoes caused by the transition from the straight silo wall to the cone bottom.
  • Continuous Monitoring: The sensors and processes were continuously monitored to identify problems, implement sensor optimization opportunities, and relay feedback to the customer for process improvements.

Results

The implementation of ABM’s remote tank level monitoring package yielded significant benefits:

  • Reliable Level Measurement: The self-adjusting ultrasonic sensors consistently provided accurate level measurements as shown in Figure 3 despite the dusty environment and material flow changes, enabling reliable inventory monitoring.
  • Time and Cost Savings: Remote setup and control eliminated the need for costly site visits and time spent climbing tanks, enhancing safety and convenience.
  • Improved Efficiency: Real-time data access ensured material never ran out, providing continuous production and enhanced operational efficiency.

Figure 3: Level over time graph depicts reliable level measurements as the silo fills and empties.

Conclusion

ABM’s remote tank level monitoring package has provided a robust and reliable solution for remotely monitoring the level of cement materials in the customer’s silos. Despite the challenges posed by the environment, the self-adjusting ultrasonic level sensors optimized remotely by ABM engineers effectively track inventory levels, ensuring accurate measurements.

With remote inventory monitoring and support, the customer has improved operational efficiency, saved costs, and enhanced inventory management.

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