Continuous Measurement of Dust in Difficult Conditions

Reliably measuring emissions in industrial plants is often very tricky. SICK has developed devices for use even in difficult conditions. The DUSTHUNTER from SICK Process Automation continuously measures dust/opacity concentrations even in difficult duct shapes and with fluctuating levels of dust concentration. This makes the DUSTHUNTER ideal for effectively and efficiently monitoring electrostatic precipitators in coal-fired power stations.

Operators of industrial plants are subject to strict directives in relation to emission of harmful airborne substances. Dust was one of the first types of emission that had to be officially recorded. More than 60 years ago, Baden-based engineer Erwin Sick developed and patented the first dust density meter.Based in the Black Forest, Erwin Sick’s company now employs over 5,000 staff, is represented around the globe and is regarded as the monitoring equipment leader for many sectors, industries and applications including monitoring dust.

Dust emissions have consistently gone down over the years as a result of improved filtration techniques. Differing dust monitoring technologies have evolved. For the broadest area of application two optical measurement procedures have become established: transmission /opacity and scattered light technology. They perform well, unaffected by the gas velocity, moisture content or charge of the dust particles, and are ideal for use downstream of an electrostatic precipitator. The monitors can be used in diverse applications and are valued for high quality and durability, low maintenance requirements and good cost/benefits ratio.

Transmission/Opacity measurement is the optimum solution for medium to high dust concentrations. This technique measures the amount of light received as a fraction of the amount of light emitted in an optical cross
stack monitoring system. Through a regression function, dust concentration in mg/m3 can be outputted. In the case of small to medium levels of concentration, the preferred principle is the physical one of scattering
light. When a ray of light hits a particle, it is diffused according to the physical laws of diffraction, refraction, reflection and absorption. The diffused light is recorded by a highly sensitive detector. It is directly proportional to the dust concentration and can be displayed via a regression function as a level of concentration in mg/m3.

The measuring technology must function stably, be easy to use and be as low-maintenance as possible. Device failure or improper handling cause high cost of ownership. “Our top priority has therefore always been
that the appliances should be durable and customer friendly. We want our clients to perceive Sick equipment as easy to use,” says Dr. Volker Herrmann, CEO of SICK Engineering GmbH.

SICK Process Automation has launched the DUSTHUNTER series as part of a new product line. The modular, in-situ dust monitors are designed to keep on working where other devices find it tough. The DUSTHUNTER series was created for industrial use with different dust concentrations, gas temperatures, wall thicknesses and duct diameters – even where there’s a large amount of turbulence in the stack – and can be adapted to extremely varied conditions. For example, innovative comparative reflection measurement enables back-scatter devices to be installed on one side only, thus making the measuring requirement particularly easy and inexpensive. As a system component, the control unit calculates and normalises the measurements and, depending on requirements, can be installed in a modular system. A large LCD display makes the monitor easy to use. Advantages of the DUSTHUNTER include reliability, durability and unusually long maintenance cycles: “DUSTHUNTER. Install it. Then forget about it!”