Analytical Instrumentation & Environmental Monitoring

Continuous opacity or dust monitoring

April 2002 Analytical Instrumentation & Environmental Monitoring

The D-R 290 opacity and dust concentration monitor from Durag is designed for continuous opacity or dust monitoring of flue gas in stacks and ductwork. It is suitable for systems firing coal, fuel oil or a mixture of fuels, converter plants, asphalt mixing plants and cement production plants, and any other type of plant requiring quantitative monitoring of opacity or dust concentrations.

The microprocessor-based monitor operates on the auto collimation (double pass) measuring principle. It has a measuring range from 0 to 200 mg/m3 up to 0 to 4000 mg/m3 with a 0,5 to 12 m path length.

A photo-element alternately receives the measurement and comparison light beam. Switching between these, it proceeds through an electro-magnetically actuated rotary diaphragm. For check value compensation, comparative measurements of 2 s occur every 2 minutes.

The D-R 290 is equipped with two analog measurement value outputs and each output has two selectable extinction or opacity ranges. The measurement ranges are selectable from 0,1 to 1,6 for extinction, and from 20 to 100% for opacity. Opacity computation of the opacity at the stack outlet is possible by means of the stack correction factor.

Periodically, the monitor automatically performs a check cycle, measuring and indicating the zero point, the soiling of the optical boundary surfaces, as well as providing a reference value. Condensation and deposits are avoided on the signal lenses by the use of a heated pane.

Mauritz van Niekerk, OEN Enterprises

011 792 2859


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