Parallel environmental measurements

Measurement of emissions using parallel analysers

Operation stops on the analysis equipment can be an expensive affair, as it can lead to discarded days which is something most plants has a very limited resource of. Too many discarded days during boiler operation can lead to large fines. Therefore, it may be a good idea to be protected against operation stops on the analysers by using parallel measurements.

Let it be said. Double measurements require double equipment, and is therefore at least double as expensive. Redundant analysers require more maintenance and are thus more expensive to operate. The environmental reporting system which has to monitor both analysers instead of one will also make this part more expensive.

Cost-benefit

The question of redundant analysers at your plant is a matter of balancing the price for discarded days with the expense for additional analysers. The few discarded days the plant has available often has to be divided among several units. This could be defect analysers, days with service on the analysers, errors in the reporting system or something else. This means you quickly end up using all days whereafter there is no more room left before operation stops are punished with fines.

The appliance of parallel analysers

In ReportLoq, it is possible to use parallel analysers for one or several components at the time. Parallel analysers can be two analysers or more which measure the same. This is done in ReportLoq by logging both measurements along with a status-signal indicating the conditions the measurements was subject to. The signal indicated whether the measurement was taken during malfunction or calibration.

Prioritised measurements

Only the value of one analyser will be used in the calculation of an aggregated hour value, if the parallel analysers are used as prioritised analysers. The reporting system will automatically switch to the secondary analyser if the primary analyser is malfunctioning or has an invalid measurement. This way, there is no risk of discarding the aggregated value as a consequence of analyser malfunction.

Redundant analysers have their own QAL2 and QAL3 values, and cost for maintenance of these must therefore be calculated. The entered values will automatically be applied in ReportLoq after entry for the specific analyser.

Average measurements

Average measurements is an option if both measurements from the parallel measurement are desired for usage. The hourly aggregated value are calculated from average of both analysers if both measurements are valid. This setup is often seen for flow meters where two ore more meters are installed in the same flue gas channel. The average of the flow meters provides a result that is closer to the actual flow. In ReportLoq, a malfunctioning flow meter will be left out of the average calculation which means it is possible to service the equipment without risking discarded intervals.

Full redundancy

Down time on the equipment can be caused by many factors. Parallel analysers naturally remove the risk on the analyser it self.

For the most safe solution redundancy is recommended on

  • Redundant data collection – Provides safety against outages on the controller that collects data

  • Redundant hardware in the environmental server – We recommend running ReportLoq on a rack server with redundant disks and power supplies. Down time on the server will not directly cause discarded days, but the lack of overview if the server breaks down can lead to indirect down time

  • Parallel measurements – as described above

Full redundancy can naturally be a very expensive solution, but it can be necessary if you balance the cost with down time on the plant. Please contact us if you are in doubt and consider if this is relevant for you. We believe stable environmental reporting is as important for you as for the environment.

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