Cellroom diaphragm

The Diaphragm Electrolysis Plant Delfzijl has a cellroom containing 184 OxyTech MDC-29 cells and an annual liquefaction capacity of 130 000 tons of chlorine. 

Most, if not all, of the world s diaphragm plants are written off since their average age is 15 years. This clearly has an impact on the thinking of cellroom owners when they consider the future of their assets (see Fig. 15.1). 

For the membrane cellroom of the same capacity there are two choices of technology type either monopolar or bipolar electrolysers. In the case of monopolar membrane electrolysers (Fig. 15.9), such as the ICI FM1500, one membrane electrolyser can replace one diaphragm cell. Since the membrane electrolyser has smaller dimensions there is an overall space saving. The monopolar membrane electrolysers may use the same pipework galleries and overhead crane from the... 

Owing to limitations on the water balance of the plant, a 40-50% conversion can be undertaken before a salt evaporator needs to be installed to remove excessive water. The feed brine for the membrane cellroom is taken from brine made from fresh imported salt and the weak brine is returned, combined with the diaphragm brine, restrengthened with recovered salt from the evaporators and fed to the diaphragm cells. The concentration of brine to the diaphragm cells could be weaker than normal, at around 270-280 g l-1 rather than 300-310 g l-1 to assist with the water balance. 

It has been shown in this chapter that financial benefits result from the conversion of a diaphragm cellroom to membrane technology. Tonnage may be increased for a similar power consumption or power usage maybe decreased for the same amount of tonnage when a conversion takes place. 

Unlike in the other two electrolysis processes, the brine is not recirculated and the temperature in the system can be chosen according to optimum conditions and therefore comparatively little titanium is used in a diaphragm cellroom. However, there are some clear candidates. An example is the cell blanket where Permascand has a newly patented design comprising bellows welded to the anode collar. The chlorine header and also the cell top are other components that could be manufactured from... 

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