Garbage incineration

As hot as hell in there

A predefined quantity of refuse from the waste bunker is placed on the combustion grate and transported through the furnace. To ensure complete combustion of the refuse, a temperature of up to 1000 °C (1832 °F) has to be maintained. Large amounts of air are injected for this purpose. State-of-the-art measurement technology enables automatic and efficient operation. Control and monitoring of the furnace are of key importance. Air quantity and air pressure must be precisely measured.

Flow measurement of combustion air with VEGADIF 55

The primary air is blown through the combustion grate from below, the secondary air from above. The air flow in each respective supply duct is measured in a section containing a venturi tube. This is a defined constricted area in the duct in which a pressure drop of a few mbar takes place. With its metallic measuring cell and suitable measuring range, VEGADIF 55 measures this pressure drop precisely. Its output signal of 4 ... 20 mA corresponds to the air flow.

Pressure measurement of combustion air with VEGABAR 52

To provide additional monitoring, the air pressure in the two supply ducts (approximately 25 to 60 mbar, resp. 0.36 to 0.87 psig) is measured by a VEGABAR 52 pressure transmitter. The furnace is constantly operated with a slight underpressure. This facilitates the influx of air for combustion.

Layer thickness measurement on the combustion grate with VEGAPULS 68

To ensure even burning, a defined layer thickness of approx. 50 cm (1.6 ft) over the grate is required. The layer thickness is measured continuously with the radar sensor VEGAPULS 68 from a distance of approx. 20 m (66 ft). This sensor measures right through the hot combustion gases at a temperature of approx. 800 °C (1472 °F) and the flames on the grate at approx. 1000 °C (1832 °F). The excellent fo-cusing of the antenna signals makes precise measurement and reproducible feed control possible.

Level measurement in the wet deslagger with VEGABAR 64 or VEGAPULS 67

The still hot cinder falls into the water-filled wet deslagger at the end of the combustion grate. A redundant, continuous level measurement with two VEGABAR 64 pressure transmitters controls the automatic discharge of the water/cinder mixture. The ceramic measuring cell of this pressure measuring transmitter is highly resistant to the abrasive cinder and is front-flush, which protects it from material deposits.

Extreme buildup and accumulation of residues can occur depending on the consistency of the cinder. In such cases, a contactless level measurement is realised by using the radar sensor VEGAPULS 67. The efficient measuring system of this instrument is not even affected by foam on the measured surface.