Sensor technology advances bulk flow measurement in cement industry

The development of sensor technology provides the cement industry with a number of potential solutions, such as lower production costs, improved quality, enhanced tracking accuracy, environment-friendly production and reduced downtime. In particular, non-contact volume flow measurement of conveyed materials can help to optimise the materials handling process from quarry to final product.

In general, conveyors are used for the movement and handling of bulk materials such as raw materials from quarries, additives, fuels, clinker and packaged cement. This movement is often unsupervised and material flow is not monitored or adjusted when necessary.

Monitoring the amount of raw material in cement plants is essential to provide a nonstop flow of supplies. Mechanical scales measure mass, while the volume of material transported is calculated using an average material density. This process is hindered when material density changes and when a conveyor belt is not properly maintained or monitored.

Bulkscan flow measurement technology from SICK automation enables the direct measurement of the contour, volume, height and material distribution through the use of light detection and ranging-based technology. The sensors can be mounted over conveyor belts or onto cranes and reclaimers.

High-pulse laser beams inside the sensor create a profile of the material on the conveyor that, in combination with belt speed, represents volume flow and calculated mass flow. This measurement principle is based on a laser beam that is deflected internally across a rotating mirror. The sequential order of the laser pulses is synchronised with the rotation frequency of the motor and the desired angular resolution. Generally, the motor rotation speed is determined by the maximum emitted pulse frequency of the laser source and the desired angular resolution. The laser beams scan the surface area of the material on the conveyor and send this information to the measurement device, which compares the data with an empty reference conveyor belt.

The device allows plant operators to directly measure volume flow on conveyor belts, bucket elevators or drag chain conveyors, both inside cement plants and in outdoor environments. The scanner can be mounted above the conveyor, measuring volume flow without any material contact. The collected data can either inform manual processes, or it can be inputted into fully automated systems to direct changes in material flow and composition. When large objects are detected, the plant operator is alerted and an automated stop process is triggered.

The same laser beams also provide information about the exact height and distribution of the bulk material on the conveyor. In addition, the centre of gravity of the load and the distance between the bulk material and the conveyor edge is measured and inputted into a closed-loop system to adjust material distribution on the belt.

The sensor can also be used in conjunction with a weigh scale, where the device measures volume and the weigh scale measures mass, allowing the actual bulk density to be determined in real time.