Electricity + Control April 2018

FLOW MEASUREMENT + INSTRUMENTATION

Electromagnetic flow meter solution – Pro- mag 100, compact flow transmitters for the tight spots around your tundish Electromagnetic flow meters are typically in use for the cir- cuit flow rate measurement. Their physical principle is based on Faraday’s law of in- duction where a voltage is in- duced in a conductor moving in a magnetic field. In elec- tromagnetic measurement, the flowing medium corre- sponds to the moving con-

Flow volume is computed on the basis of the pipe’s diameter. A constant magnetic field is required for accurate measurement.

Figure 1: Leakage detection system.

ductor. The induced voltage is proportional to the flow velocity and is detected by two measuring electrodes and transmitted to the amplifier. Flow volume is computed on the basis of the pipe's di- ameter. A constant magnetic field is required for accurate measurement. This principle of measure- ment is important not to install the flow meter so close to the Electric Arc Furnace’s electrical field. The flow meter can with stand in an external elec- tric field of 90 Gauss (9.10³ tesla). The flow meters are developed to show more process values than ever. All of them are available on a digital network. Assignable measured variables on the current and frequency outputs: • Volume flow • Mass flow • Corrected volume flow

System parameters • For 1 - 15 cooling circuits • Alarms of flow differences (>=0,3% under ref- erence conditions) • Temperature range: 0 - 99°C • Flow range: 10 – 2 700 m 3 /h • Pressure range: 1 – 10 bar • Safety integrated system according to IEC61511 [2]/ EN ISO13849-1 [3] Malfunctions in water circuits can be very danger- ous to both equipment and personnel. Regardless of the cooling circuit type, principles for leaking detection are as follows: the inlet and outlet flow rates of a cooling circuit are measured by means of suitable flow meters, either electromagnetic or ultrasonic. The inlet and outlet temperatures are also acquired from sensors mounted in close prox- imity to the flow meters. Our system uses sep- arate temperature sensors to achieve maximum accuracy. Max. allowed external magnetic field: 90 Gauss (9,10 3 tesla) (Corresponds e.g. to a lead with a max. current of 110 kA and distance of approx. 10 m from the flow meter) Safe, robust and precise water leakage monitoring

• Flow velocity • Conductivity

• Corrected conductivity • Electronic temperature • Temperature

In a furnace leakage detection application we can see added value in using temperature measure- ments to support the control. This can serve as an additional temperature in-line to confirm if the independent temperatures are correct; tempera- ture is a critical measurement in this application. In addition, conductivity can be a water quality meas- urement that can be related to concentration and possible scaling in the line. If your lines become re- stricted because of blocking/ calcification the cool-

Electricity + Control

APRIL 2018

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