DE NORA SANILEC SEAWATER ELECTROCHLORINATION SYSTEMS
Pressurized seawater is delivered to the SANILEC system where it is strained to 0.8 mm to remove suspended solids. The seawater passes through a flow control assembly, which may include a flow control valve, and a flow transmitter with local indication and low flow shut down protection. The seawater then passes through the electrolyzer cells and exits the cell as sodium hypochlorite solution and byproduct hydrogen gas.
The solution is piped to a tank or cyclone where hydrogen is removed from the solution.
The hydrogen is typically diluted with air using a set of redundant blowers to a safe level (typically less than 1%) Finally, the sodium hypochlorite solution is injected at required continuous and shock-dose rates.
The process is based on the electrolysis of seawater as it flows through an unseparated electrolytic cell. The resulting solution exiting the cell is a mixture of seawater, hypochlorite, and hypochlorous acid.
Electrolysis of sodium chloride solution (seawater) is the passage of direct current between an anode (positive pole) and a cathode (negative pole) to separate salt and water into their basic elements. Chlorine generated at the anode immediately goes through chemical reactions to form hypochlorite and hypochlorous acid.
Hydrogen and hydroxide are formed at the cathode, the hydrogen forms a gas and the hydroxide aids in the formation of hypochlorite and increases the exit stream pH to approximately 8.5.
This overall chemical reaction can be expressed as follows:
(Salt + Water + Energy = Hypo + Hydrogen)
NaCl + H2O + 2e = NaOCl + H2