The ABB LM200 laser level transmitter as shown in Figure 1 has been successfully applied at a cement manufacturing facility in the USA for “clinker level” measurement.
Figure 1. ABB LM200 laser level transmitter
The LM200 Laser is a laser-based distance measuring instrument used in process control systems. Distance is determined by an on-board microprocessor by multiplying the speed of light by the time it takes for a laser pulse to travel from the instrument to a target and back.
Infrared, invisible light is used by the measuring laser. In order to help with the alignment of the measuring laser, there is a second, visible aiming laser. The laser beams have very little divergence so that accurate targeting is easy even in silos or vessels that have internal structures.
The key features of the ABB LM200 are:
- Maintenance free, non-contact continuous level sensor
- Range up to 190 m (623 ft) for level applications
- Range up to 400 m (1312 ft) for positioning applications
- Easy and intuitive setup
- No calibration required
- Continuous level monitoring for granular solid materials and opaque liquids
- Measures solids and opaque liquids at any angle
- Last Pulse Detection for Measurement with Light and Moderate Dust
- Built-in laser pointer for accurate alignment in narrow or tall vessels
- Auto-ranging to measure all levels
- Available non condensing heated optics prevent condensation issues
- No Beam Divergence = No False Echoes
- Rugged and Robust Aluminum Enclosure
- CSA, ATEX and IECEx potentially explosive atmosphere ratings
The application for which the ABB LM200 laser level transmitter was used involves the measurement of clinker, which is limestone with other ingredients blended and heated to about 2500° F as it is processed in the cement plant, which is shown in Figure 2.
Figure 2. Cement plant
These facilities normally have access holes in the floor to enable them to visually monitor the process conditions. The only practical measurement technique is non-contact measurement. Large size clumps and a very uneven surface that characterize the process complicate the problem.
This customer along with many others had tried to use ultrasonic devices but was affected by the high temperature off of the process material and the uneven surface. Radar level sensors can determine the surface of hot materials but uneven surfaces can create false echoes that make the reading erratic.
The LM200 Laser level transmitters are the perfect solution as they offer the following benefits:
- Not affected by the temperature since it can be mounted away from the process and still measure the level.
- Not affected by the shape or size of the process material.
- Not affected by the peaking and slumping of the material.
- Totally non-contact and can be mounted on the outside of a window if necessary.
The fittings in the floor need to be at least 5 inch and preferably 6” due to the fact that the pipe attached to the fitting causes some reflection of the laser beam. (The laser lens pair are 10 cm (4”) in diameter)
About ABB Analytical Measurements
ABB is a leader in power and automation technologies that enable utility and industry customers to improve performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 145,000 people.
This information has been sourced, reviewed and adapted from materials provided by ABB Analytical Measurements.
For more information on this source, please visit ABB Analytical Measurements.