EXPERIENCES FROM A ROUND ROBIN TEST FOR FLUE GAS TEMPERATURE, VOLUME AND FLOW MEASUREMENTS

ABSTRACT
In Flanders, laboratories, recognised for emission measurements in the framework of the environmental legislation (Vlarem II), have to implement a quality system that meets the requirements of EN 45001 and are forced to participate in external quality controls organised by AMINAL, the Flemish Administration for environment and/or the reference laboratory for air measurements, e.g. Vito (Vlarem, Art. 1.3.3.1.).

In September 2000 a first test for physical parameters was arranged including the determination of flue gas temperature, volume and flow. The aim of these tests is a comparison of the results of the individual participants
with the reference value and with each other.

Different gas temperatures were generated in a fluidised sand bath.

For volume control tests, an Automated Gas Flow Calibration System, the Bell Prover, with a total volume of about 600 l was used.

Gas flow measurements were performed in a wind tunnel with a total length of 6 m and an internal diameter of 50 cm. A constant flow was generated by a frequency regulated fan. Homogeneity over the total diameter was
ensured by a grid placed just in front of the fan.

The equipment was proved to fulfil the demands of accuracy, reproducibility and traceability.

From the results of the 23 participating laboratories it was concluded that 4, respectively 3 participants show a deviation of more than 1% versus the low and high temperature. Only 5 laboratories had a deviation of more
than 10 % compared to the reference volume. The gas velocity results of 18 respectively 20 participants were at least 95% of the reference low and high flow rate.

From the experiences with this ring test it was also concluded that the usefulness of the results could be improved by limiting the allowed equipment, e.g. 1 type of Pitot tube, use of operational field equipment only…

INTRODUCTION

On 6 September 2000 a round robin test was organised for laboratories, recognised for emission measurements in the framework of the environmental legislation in Flanders. The parameters temperature, volume and flue gas
velocity were tested. The aim of the test was to compare the results of the individual participants with the reference value, to obtain an estimate of the overall uncertainty of the measurements and to reveal eventual large
systematic errors.

23 participants subscribed. They were explicitly asked to use operational field equipment.

The test equipment as well as the results of the round robin test are presented in the next paragraphs. The results were reported anonymous. Each participating laboratory is given a complete report but only knows his own participant number.