Power plants near the shore often use seawater for their cooling systems. Before entering the circuit, it undergoes a complex filtering process to prevent damage to the system caused by residues. Continuous filter monitoring of the seawater cooling system is essential for reliable operation. Differential pressure transmitters have proven themselves for this task.
The sea is an inexhaustible resource for cooling processes in power plants. Pumps convey tens of thousands of cubic metres of water into the circuits every day. This flood also washes up stones, sand, shells and plastic waste. Filters catch these materials. Their screens must therefore offer lasting protection. And this not only applies to solids; the filters for seawater cooling are also intended to prevent mussel larvae infestation in the system.
Filter monitoring for seawater cooling via differential pressure: Robust instruments
Model DPT-20 differential pressure transmitter with flange connections and capillaries: WIKA has specified such a version for filters in seawater cooling circuits.
For their task, the filter screens must be designed with correspondingly fine pores. They can therefore easily become clogged. Measuring the differential pressure on the screens provides a clear indication of their degree of contamination. When a defined limit value is reached, a flushing process is started which quickly removes the deposits from the screens.
Filter monitoring in a seawater cooling system requires robust differential pressure measuring instruments for screen monitoring that can permanently withstand the salinity of the water. A filter manufacturer uses appropriately specified model DPT-20 differential pressure transmitters from WIKA for this purpose.
The process adaptation at the two measuring locations is realised using model 990.28 diaphragm seals made of 316L stainless steel. Their wetted components, i.e. the diaphragm and the sealing face, are made of Hastelloy C276 for saltwater applications. This special material guarantees the desired durability of the instrumentation.
High accuracy enables permanently reliable filter operation
The diaphragm seals transmit the pressure via a 2.5 metre capillary to the transmitters, which convert it into a 4 … 20 mA output signal and transmit it via the HART® protocol. The measuring instruments operate in the specified measuring range of -500 … +500 mbar with an accuracy of 0.1 percent of span. This performance enables power plant operators to ensure permanently reliable filter operation.
However, WIKA was not only awarded the contract by the filter manufacturer because of the quality of the measuring instruments, but also because, despite a deadline of only five weeks, the complete delivery of the specified instruments required arrived at the customer on time.
Note
On the WIKA website you will find further information on the model DPT-20 differential pressure transmitter and the model 990.28 diaphragm seal. There you will also find an overview of other measurement solutions for the power generation and water and wastewater industries. If you have any questions, your contact will gladly help you.
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This video explains the many benefits of differential pressure measurement