Although today electronic systems are used all around the world, in most cases for boiler monitoring, mechanical controllers and limiters still ensure safe operation of a steam plant, especially in tough environments. These devices are easy to maintain without the use of highly skilled staff.
With electronic systems, electrodes are used as measuring devices.
They use the electrical conductivity of the boiler water to detect whether the tip of the electrode rod is in the water or in steam occupied space. Depending on the application, the electrodes are located in a housing attached outside the boiler drum or in a protective pipe inside the boiler.
During ongoing and continuous operation the substances suspended in the water are concentrated in order to avoid the negative consequences (foaming, deposits) of excessive salt content in the boiler water, specified limit values must not be exceeded.
With the aid of a desalting control valve the boiler water concentrated content is constantly removed and replace with clean water. If the limit value is exceeded the conductivity limitation ensures prompt shut off of the burner.