Water treatment
The raw water is first conveyed to the degassing system. Four vacuum pump units generate a vacuum of 27 mbar in a degasser vessel. As a result of the vacuum, the gases in the raw water are released and can be drawn off.
Alternately, two speed-controlled, double-flow booster pumps draw in the water from the degasser and compress it in two oxidators, in which oxygenation, which is necessary for the deferrization process, occurs through the distribution of the water flow and air supply. In the 1st filter stage, the deferrization and a partial elimination of organic substances take place. This comprises six deferrization filters working parallel.
Downstream from this is the deacidification stage (two trickle systems) with simultaneous oxygenation.
The water which flows off via a chute is conveyed to the 2nd filter stage, where de-manganizing takes place in eight parallel filters. The filtration over limestone achieves a hardening of the water to reduce its corrosiveness.
The filters are back-washed using rinse water and compressed air, the same rinse air blowers being used for both stages. The rinse water consists of inherent filtrate to prevent problems with the processing effect through modified chemical values. The first stage is rinsed with a filtrate pressurized by a booster pump, while the second stage includes rinse water pumps which are supplied from the screened water collecting pipe.
The controls
The Hafen- und Industrietechnik GmbH has modernised and visualised both waterworks. The old AEG-controls were replaced step by step by a Siemens-S7 (3 x S7-414-3 und 4 x S7-315-2 DP) during operation-s. The complete PLC includes 4500 inlets and outlets and was “fully-automated” during the course of the modernization, so that the control room at the waterworks is no longer manned. The most important error messages and displays are now transmitted to the main control room, which also supervises and controls the areas electricity and gas.
The main waterworks is running nonstop for basic requirements, whereby the smaller waterworks is triggered automatically should the demand make it necessary. This is the case several times a day for longer periods of time.
Why HIT?
HIT implemented this project to the full satisfaction of the client. From the very beginning, the system proved its reliability. Through the full automation of the water treatment and the integration of the control level into the main control room in Wilhelmshaven, it has been possible to optimise staffing levels.
