Reasons for the increase in slot voltage
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This post was last edited by sunjl1981 on 2013-1-6 at 23:26. Phase 3 of our plant is a 5Wt/year ion-exchange membrane caustic soda production facility; it uses BITAC899 cells from the chlorine production unit, with 104 N2010 membranes and 193 N2030 membranes. However, recently the cell voltage has been rising continuously, power consumption is very high, and it seems that it’s now difficult to achieve a daily production volume of 150 tons of caustic soda! The quality of the saltwater is within acceptable limits; aside from relatively high levels of iron and iodine, everything else is fine. The iron content is generally between 200 and 220, while the iodine level is over 200! The operation status of the equipment is as follows: it came online in October 2007. At the beginning of February 2008, due to quality issues with the plates in column B, two sets of plate units were removed from that column and replaced. After reinstallation, pinhole tests revealed the presence of pinholes in units 4 and 48 of that column, so the plates were removed again and replaced with new ones! Analysis results: The chlorine purity in column A is around 98.5, 98.8 in column B, and 98.6 in column C; the purity of the chlorine main pipeline is 98.5. The current DC power consumption is 111,000–112,000 units per 8 hours, resulting in an alkaline production rate of 50.2 tons per 8 hours. I would like to ask the experts here: could the conditions I mentioned above be a factor that affects the cell voltage? If not, please help analyze it! # ， ， &
As can be seen from the data provided above, the exchange performance of the membrane declines, the cathode current efficiency decreases, and the membrane pressure drop increases. It is necessary to calculate its economic lifespan; if required, the membrane should be replaced.
Based on your description, I personally think it’s not due to the membrane. As for DUPONT membranes, the FE and I values you mentioned are not sufficient to cause such a rapid increase in slot pressure; moreover, the effect of iron would not be that significant, especially in the case of DUPONT membranes. You can check if there are any issues with the coating on your electrodes
The membrane is contaminated by heavy metals; the concentration of the anode solution is low. When acid is added to the anode, care should be taken to ensure that the acidity is not too high. The concentration of the cathode solution is high; the temperature of the electrolyte is low, as is the temperature of the cell. There may also be rectifier faults, etc
Abnormal current fluctuations, abnormal concentrations of the anode and cathode solutions, membrane blockage, damaged negative electrode components