|Abstract Title:||Continuous Dust Emission Monitoring with Optical Measurement Technologies|
|Presenter Name:||Mrs Sarah Luehmann|
|Session Choice:||Continuous Emission Monitoring|
Abstract Information :
Most industrial combustion processes require continuous monitoring of dust emissions. Optical technologies offer the most reliable methods among the available techniques since the measuring results are independent from the gas velocity, particle charge and gas humidity. Optical dust monitors are based on the interaction between visible light and the dust particles in the flue gas duct. Two distinct optical measurement principles can be applied for dust emission monitoring: the transmission principle and the scattered light principle. The transmission principle is ideally suited for the measurement of medium to high dust concentrations in stacks with large diameters. For monitoring low dust concentrations in stacks with small diameters the scattered light principle is ideally suited. Scattered light dust monitors analyse the light scattered in a forward or in a backward direction. They allow detecting dust concentrations below 1 mg/m3 and play an important role for the monitoring of low-emission combustion processes.
In recent years, a continuous decrease of worldwide energy-related dust emissions was observed. Key contributions have been the change to low-emission energy sources and the efficiency enhancement of filter units. In many countries in the world, especially in Europe, the emission limit values for particulate matter have continuously been tightened. The worldwide trend of lower emission limits for dust raised high requirements for dust measuring devices. Monitoring devices must ensure the continuous, precise and reliable monitoring of lowest dust concentrations in order to meet future standards. In Europe, measuring devices for official emission monitoring, so-called automated measuring systems (AMS), are subject to strict quality assurance criteria and require a performance test by a certified body (QAL1 certification according to the European standard EN 14181) in accordance with the European standard EN 15267-3.
To ensure reliable measuring values at any time, continuous dust measuring devices typically include internal control functions, such as zero point and reference point check for continuous validation. Typically, optical dust monitors have provisions preventing the contamination of the optical system and compensating for contamination effects.
The presentation reviews different optical measurement technologies for continuous dust monitoring, the advantages and disadvantages as well as typical applications. Dust measuring devices based on the scattered light principle are discussed in detail since they are expected to dominate the continuous monitoring of very low dust concentrations. Quality assurance methods by means of internal audit functions are reviewed. The presented technologies allow plant operators real time monitoring of different levels of dust concentrations with minimum maintenance effort at maximum precision.