Control and monitoring of the production sequence in a refinery

In the refinery crude oil is cracked by distillation to give petroleum, kerosene and diesel oil. In the fractional distillation column the crude oil is heated with superheated steam. The vapors and liquids released collect in the various stages of this column. To control and block the flow of gases and liquids the spindle drives of the numerous flow control valves are fitted with long-stroke sensors. An aluminium tube is used here as the measurement object which is moved concentrically over the sensor coil rod without making physical contact. A displacement signal in the range 4 to 20 mA is provided for the aluminium tube position or for the valve position.