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News and press

"D-R 909 uses a very precise scattered light measurement"


Hamburg, August 9 2023 Our new D-R 909 dust measurement system scores particularly well in regulatory emission monitoring. This is mainly due to the patented measuring cell D-R CL, which measures scattered light. In the interview, our product manager Mathias Klostermann provides more information about the special features of the QAL1-approved measuring system of the DURAG GROUP.

Mr. Klostermann, can you describe the new D-R 909 extractive dust measuring system in one sentence? 
The D-R 909 impresses with its patented measuring cell, automatic control functions, high availability, low service and operating costs, as well as installation that is as simple as it is flexible.

Which areas of application are typical for the D-R 909?
The dust measuring system of the latest generation can be used in regulatory emission monitoring. Wherever wet flue gas is present or changing operating conditions can lead to the formation of liquid water in the flue gas, the D-R 909 is the right measuring system. Waste to energy plants or coal fired power plants that rely on wet scrubbers for flue gas cleaning are possible application fields.

What technology is the D-R 909 based on?
The D-R 909 combines extractive sampling, preparation of this sample and dust measurement in one instrument. The sample preparation is designed to correctly detect the dust content even in samples that are completely saturated with water vapor. This also works with small water droplets, comparable to fog. The liquid present is evaporated in order to subsequently detect only the scattered light from the dust particles. The forward scattering principle used in the measuring cell provides very precise measurement results, especially for small and medium dust concentrations.

Can you describe the functionality in more detail?
The heart of the system is our patented measuring cell. In this cell, a red laser beam is directed at a defined measuring volume. If a dust particle flies through this measuring volume, the light from the laser is scattered onto a light-sensitive detector. The more particles fly through the measurement volume, the higher the measurement signal. The device then converts the measurement signal into the corresponding dust concentration.

What makes this measuring cell so special?
The measuring cell detects the smallest light intensities, but is hardly susceptible to interference. Both properties are usually at odds with each other. We have succeeded in raising the bar with a new patented concept. We achieve this with systematic compensation of changes in optical interfaces and automatic background light correction.

What should plant operators expect in terms of operation and maintenance? 
A growing number of our customers are considering not only the investment costs for procuring and installing the measuring systems, but also the maintenance effort and operating costs. The total cost of ownership should be as low as possible. For us, avoiding deposits caused by measuring gas was a very high priority. The innovative design of the D R 909 fulfills this requirement sustainably. This is also confirmed by our experience so far. We have greatly reduced the time required for regular maintenance and performance checks. This is ensured by the automatic control functions and the easy-to-perform linearity test. The power consumption of the entire system reaches a market-leading low level.


Click on the link below to learn more about the dust measuring system D-R 909.