Application
The chlor-alkali industrial process is the production of chlorine, caustic soda solution and hydrogen, from an aqueous solution of alkaline chlorides by the application of a direct current (electrolysis). The three most common methods used are: the amalgam process, the diaphragm process, and the membrane process. The membrane process is becoming the predominant process based on reduced energy consumption, lower investment costs, and lower environmental risk.
IEM Cell Layouts: Finite Gap vs. Zero Gap
In the design of a membrane cell, minimization of the voltage drop across the electrolyte is accomplished by bringing the electrodes close together (finite gap).
However, when the gap is very small the voltage increases because of the entrapment of gas bubbles between the electrodes and the membrane. A non-uniformity in current distribution can also occur because of localized narrowing of the anode/cathode gap due to electrode profile variations.
By pushing the anode and cathode against the membrane (zero gap), the operating voltage can be minimized and the current distribution made uniform. This is achieved by inserting an elastic element (knitted nickel wire mesh) between the cathode and the current distributor.
