| Abstract Title: | Continuous monitoring of fine dust emissions: challenges and perspectives |
| Presenter Name: | David Graham & Rupert Standring |
| Company/Organisation: | Uniper |
| Country: | United Kingdom |
Abstract Information :
As dust mass concentrations emitted from Energy from Waste (EfW) plant have fallen, due to improved abatement technologies and the imposition of stricter Emission Limits Values (ELVs), it has become progressively more difficult to calibrate dust CEMS. This is largely due to the difficulty of obtaining meaningful results with the manual Standard Reference Method (SRM), that is used to calibrate the CEMS, which measures the mass of dust particles captured on a filter when drawing a flue gas sample of known volume from the stack. However, the mass concentration may also be lower than the detection limit of the installed CEMS. In the UK, this has been addressed by using the CEMS as an indicative monitor, although this creates difficulties when assessing compliance.
SRM performance is reviewed in this presentation, based on published data and test methods, focussing on the actions that are needed to lower detection limits. Ultimately, alternative test methods are needed.
CEMS performance is also reviewed, noting that sensitive light scatter devices are predominantly fitted to EfW plants in the UK. These rely on the detection of light that is scattered by particles in the path of a laser beam. Consideration is given to obtaining the best performance from these CEMS so that they can be used semi-quantitatively, rather than indicatively.
However, the light scatter CEMS response is also sensitive to particle size which leads to an increased measurement uncertainty related to the variation of the process dust properties (rarely considered). This also means that, during short periods of abatement malfunction, when the particle size is higher than usual, the CEMS will under-read.
A review of both certified and uncertified dust CEMS, in both Europe and the US, has shown that there are uncertified instruments available that measure mass concentration directly. Others measure the particle size distribution, thus removing the sensitivity to particle size but requiring an assumed particle density. In this latter case, the CEMS also provide information on the fine particle fractions, such as PM2.5, that are particularly important with regards to human health impacts. Air quality monitors, that are used for ambient dust measurements, could also be considered for measuring dust in diluted flue gas. These approaches could be considered for use as alternative reference methods.
This presentation reports the literature review work conducted within a wider project on PM2.5 emissions that was commissioned by the UK Department for Environment, Food & Rural Affairs.
