ABSTRACT
The water demand in Middle East has forced the countries to build large desalination plants. The seawater is fed to the distiller after filtration, chlorination, degasification and chemical treatment. The seawater passes through different stages recovering thermal energy till it is heated in brine heater to a temperature of about 105 oC. The concentrated brine is flashed at high pressure and temperature to release vapors in different number of stages. These vapors pass through demister in the roof of brine chamber to be separated from the entrained brine droplets. Later the vapors condense on tube surface transferring energy to recirculating brine through the tube bundle in each stage.
The corrosion problem in desalting industry is addressed with great caution due to chlorinated seawater medium at high temperature and different pressure. All possible corrosion prevention techniques are applied to minimize the severity of corrosion. From proper materials selection to chemical treatment and application of cathodic protection are applied. The object of the present research is online monitoring of corrosion at the selected location in desalination plants. The analysis of the collected results provides the choice of right chemicals and application of the correct dosage of chemical additives and minimizes the use of excessive supply of impressed current in cathodic protection. For online corrosion monitoring a corrater that works on the principle of linear polarized resistance method have been applied at four locations. The data collection is manual but can be connected to data logger and alarm system to take necessary action promptly. This application can reduce unnecessary shutdown time and provide information to control and operate the unit at its maximum capacity with the best performance and reliability.
