VEGAPULS 69 level sensor secures coal supply in an Indonesian power plant

Without a reliable supply of coal, even the best power plant couldn’t deliver the required energy, so reliably monitoring the coal reserves becomes absolutely essential.

The coal is delivered by sea and unloaded into bunkers up to nearly 100 feet high. Coal is transported to these bunkers from the stockpiles of the power plant via conveyor belt systems above or below ground. From there, the coal has to be transported to the mills where it is ground into a fine powder for subsequent combustion in the combustion chamber of the furnace.

Reliable level sensors are required at every step of the way to prevent overfilling in the bunkers and ensure uninterrupted charging in the combustion chamber. Continuous monitoring of the minimum level in the coal dust silos is especially critical, because a supply interruption to the furnaces must be avoided at all costs.

Unfortunately, the prevailing ambient conditions in coal bunkers are not the easiest – any sensor quickly gets covered with dust and dirt. At the power plant in Tanjung, the company regularly struggled with a measuring point that was supposed to display the precise height and resultant quantity of the coal reserves. Unfortunately, the reading constantly jumped to the 100 percent value despite the actual level sitting close to zero. The dusty environment, the loud filling noises, and the typical bulk material distribution in the bunkers all caused problems for the measuring instrument.

The power company had a number of good experiences with VEGA products at other measuring points in the plant. The power plant uses a VEGAWAVE 62 in the fly ash silo, a VEGAPULS WL S 61 for a wastewater measurement, and a VEGAPULS 64 for measuring the level in the chlorine tank just to name a few examples.

When it came to this difficult measurement, they asked the radar experts in Schiltach for some advice. They recommended VEGAPULS 69, which offers great reliability, especially in dusty, dirty environments due to its 80 GHz high measuring frequency. The sensor was first demonstrated in a small seminar room with the help of a canopy as the level and books as objects causing interfering signals. The presentation was convincing enough, despite the improvised setup. The company decided to give the VEGAPULS 69 a chance.

Ever since its market launch, the VEGAPULS 69 has been regarded as a robust problem-solver. With a measuring range of up to 120 m and an accuracy of ±5 mm, the sensor was more than enough, even in the most challenging applications. The bunker height of nine meters was no problem for the VEGAPULS 69.