Condenser having apparatus for monitoring conditions of inner surface of condenser tubes

A condenser including a plurality of condenser tubes through which a coolant is caused to flow, a device for injecting ferrous ions into the coolant before it passes through the condenser tubes to form a protective film on an inner surface of the condenser tubes, and a device for introducing sponge balls into the condenser tubes for cleaning their inner surfaces. The condenser has a by-pass line extending outside the body of the condenser, in parallel connection with the condenser tubes. The by-pass line has a monitor tube of the same material and size as the condenser tubes, so that the coolant flows through the monitor tube under the same conditions as the coolant flowing through the condenser tubes. The monitor tube is equipped with a device for measuring a polarization resistance of the monitor tube, and a device for sensing a fouling condition of the inner surface of the monitor tube. The injection of ferrous ions into the condenser tubes and the cleaning of their inner surfaces with the sponge balls are adjusted in response to the measured or sensed polarization resistance and fouling condition of the monitor tube.