Feuchtemesstechnik in der REA-Gips Produktion
24.04.2017 | von Michael Stoll
Der Einsatz von Feuchtemesstechnik kann bei der Reduzierung der Umweltbelastung von Kohlekraftwerken eine bedeutende Rolle spielen. Im Kohlekraftwerk MPP3 in Rotterdam, Niederlande, wird durch die Reinigung des Rauchgases unter anderem REA-Gips erzeugt. Nach der Rauchgasentschwefelungsanlage des Kraftwerks überwachen und steuern vier Feuchtesensoren die Trocknung des Gipses auf den beiden Vakuumbandtrocknern.
Kohlekraftwerk MPP3 in Rotterdam-Maasvlakte / NL
The “MPP3” is the most modern and biggest hard coal fired power plant with the notable gross power rating of net 1070 MW and a net efficiency of over 46%. The “MPP3” wants to reduce the effects on the environment as much as possible. One point to reach an environmental friendly process is the optimisation of the exhaust-desulphurisation unit. The desulphurisation is made by a wet flue gas cleaning unit controlled by a moisture measurement. This flue gas desulphurisation (FGD) is far more effective than in other traditional coal fired power plants. Beyond the “MPP3” can reach a biomass-combustion up to 30%. Of course the district heating is used from the adjacent companies.
The desulphurisation is based on burnt lime (CaO) thereby the end product gypsum (calciumsulfad-dihydrat) arises. For the analysis of the produced gypsum there is an in-house laboratory located in Maasvlakte (Rotterdam). This in-house laboratory evaluates all the recurrent samples that have to be taken to supervise the moisture content of the gypsum. The REA-gypsum can only be traded and further processed with a moisture value around 10%. Based on this fact a continuous measuring and storage of the actual moisture value is indispensable. To avoid caking in the whole process and to guarantee the best flow characteristics in all following transport systems, a moisture measurement system is also advisable.
More possibilities for application of FGD-Gypsum and gypsum fiberboards
Installation der Feuchtesensoren in der REA-Gips Produktion
One very important thing of moisture measurement systems is the mounting condition of the sensor. A constant material height and density should be given. To guarantee such optimal process conditions a special scraper is installed in front of the sensor. Furthermore the sensor is mounted on a sledge. This also improves the surface of the material and reduces material caking in front of the sensor. By hand-wheel the material height and the sensor position is adjustable very fast and easily.
Earlier experiences have shown that just one sensor, on a 2.4 meter wide belt, is not sufficient for an accurate moisture measurement. Due to this the moisture measurement consist out of two sensors. On one hand the repetability is higher and on the other hand the function of the sealing lip can be monitored (safety function). If there is a damaged sealing lip, the vacuum and consequently the drying process will not work as good as before. On one sensor the moisture value will increase highly. In this case the sealing lip should be replaced.
