| Abstract Title: | Gas Sampling and Conditioning: The hidden Champion in CEMS Systems |
| Session Choice: | Continuous Emission Monitoring |
| Presenter Name: | Mr Jörg Erens |
| Company/Organisation: | AGT-PSG GmbH & Co. KG |
| Country: | Germany |
Abstract Information :
The cold extractive measurement is “still” the number one choice for the measurement of emissions. All past research and development activities for in situ technologies come to their limits, either in technical or commerical perspective. For niche applications there is a growing market but the majority will also in the future be served by extractive systems. Within the group of continuous extractive measurements two analyser methods need to be separated: hot wet (such das FTIR or FID) and cold dry technologies (such as UV / IR / NDIR). As soon as the continuous extraction of the gas is required one field comes into focus which is probably one of the most underestimated ones: the gas sampling and conditioning system upstream the analyser.
Strong impact on the results
As per definition it is the task of the gas sampling and conditioning system to provide a representative sample of the exhaust gas to be measured without falsification. Another very important aspect is the stability and reliability over the operation times:
Avoid the avoidable
Almost all of the avoidable manipulations caused by the sampling and conditioning systems can be eliminated by choice of high quality and reliable gas sampling and conditioning components. The presence of condensate for example can be avoided by ensuring the right temperature of the primary gas sampling (gas sampling probe) and the right temperature of the heated sample line (high acid due points have to be considered) – nevertheless also small cold spots as interface between the gas sampling probes and heated sample lines have to be avoided.
Sample gas changes have to be stable
Other changes of the sample gas which cannot be avoided need to be stable in order to be eliminated by calibration of the analyser. Due to the interference of H2O with IR analysers the sample gas has to be dried before the analysis process. The most comment way is to use a gas cooler which uses a heat exchanger in order to transfer the hot gas into the dry gas phase – in this transition side effects like the wash out of water soluble gas components (e.g. SO2) in the condensate are a problem which can not be avoided with 100 %. It is the challenge of the perfect gas sampling system to optimize not only the wash out rate but also make sure that the outlet due point is constant and low. Only if a low washout and a constant outlet dew point come together the loss can be eliminated reliably by calibration.
The future: Sharing data also from the sampling and conditioning system?
As differentiation from the beginning of emission monitoring the stability of the measuring process is not only required in laboratory setups – in frequent tests and procedures (e.g. defined in EN15267) the full system has to proof its performance in daily operation. As the impact of the sampling system clearly shows the importance for reliable measuring data the authorities might one day require and consider also detailed data about the condition of the gas sampling system.
