METHOD FOR PREVENTING DEPOSITION OF SCALE IN EVAPORATION TYPE SEAWATER DESALINATION APPARATUS

摘要

PURPOSE:To prevent deposition of hard scale at the inside of a heat transmitting tube and to ensure a continuous operation of the titled apparatus by removing gaseous CO2 by adding an acid to the supplied seawater followed by separating Ca components by adding an alkali metallic salt. CONSTITUTION:The supplied seawater is sent to a heat releasing part 3 of an evaporation type seawater desalination apparatus through a line 101 to condense flashed steam in the part 3 into fresh water which is flowed out from a line 14. A part of the supplied seawater whose temp. is hereby increased is branched to a line 12 and is added with an acid from a line 102, then CO2 is released by blowing air with a pump 5 in a decarbonation tower 4. After releasing gaseous CO2 an alkali metallic salt is added from a line 104 to remove the incorporated Ca components in a solid-liquid separator 6. After removing Ca, the resulting liquor is mixed with a circulating brine in a flashing chamber of the part 3 and is passed through a heat transmitting tube in a heat recovery part 2 to condense the flashed steam in the part 2 into fresh water. Then it is heated by a brine heater 1 and is introduced into the flashing chamber in the part 2 to generate flashed steam.