The relationship between the current efficiency of the electrolyzer and the consumption of raw salt
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This post was last edited by sunjl1981 on 2013-1-6 at 20:18. As we all know, when a certain current is applied to an electrolyzer, sodium chloride is consumed, and sodium hydroxide as well as hydrogen and chlorine gas are produced; it is merely the presence of side reactions that determines the efficiency of the current utilization! My question is: when the current efficiency is low, does it mean that the amount of product produced by the electrolyzer is low, and consequently the amount of sodium chloride used is also low? And when the current efficiency is high, does it mean that more product is produced by the electrolyzer, and thus more sodium chloride is consumed? A few days ago, one of our electrolyzers had its ion membranes completely replaced. After it started operating, the current level remained the same as before, but the amount of brine and pure water added to it increased accordingly! What is the reason for this then? # ， ， &
Current efficiency can be understood as the ratio of the actual power consumption for alkali production to the total power consumption of the electrolyzer. When the current efficiency of the electrolyzer is low, more electrical energy is converted into heat or other forms, resulting in a low output. But production capacity and salt consumption are fixed. After replacing the membrane, the current efficiency improved; with the same total amount of electricity used, more product could be produced, resulting in higher profits. I’m not sure if my understanding is correct This post was last edited by pzhhuagong on 2009-2-25 16:04.]
Current efficiency, which is what we generally refer to as cathode efficiency, is closely related to power consumption. As for salt consumption, I believe its impact in this regard is not significant, as the chlorates produced by side reactions continue to circulate within the system; if a chlorate decomposer is available, it will help maintain equilibrium in the system； If what the original poster means is anode efficiency, then what needs to be taken into account is the chlorate produced as a side reaction, which will reflect the consumption of sodium chloride; but can this be reflected in the consumption figures? Personally, I think it’s unlikely to be achievable given the current level of measurement in the chlor-alkali industry.
Have you calculated the current efficiency after replacing the membrane?/It should be high, right?
The efficiency is related to the membrane’s ability to block hydroxide ions as well as the activity of the coating; it has nothing to do with the total amount of sodium chloride used, but is related to the per-unit consumption, since the amount of alkali produced changes； In a natural circulation cell, the flow rate of brine entering the cell is only related to the current; as for whether an increase in the amount of pure water added is related to the concentration of the brine solution, that remains to be determined.
By considering only the sodium ions entering and leaving the entire system, a high current efficiency means that more alkali can be produced with the same current level. The alkali contains less salt, as well as lower levels of chlorate. Since salt consumption is calculated based on the amount of sodium chloride (sodium ions) used divided by the electrolyte (sodium ions in 100% sodium hydroxide), theoretically, lower levels of salt and chlorate in the alkali result in less sodium ion loss and thus lower consumption. However, these concentrations are at the ppm level, so they can be ignored. Therefore, current efficiency has little impact on salt consumption.
The saline flow rate should correspond to the current; when a new membrane is used, the current efficiency increases, which means that the side reactions that used to occur are reduced. The consumption of Na ions is mainly related to the current intensity, while the impact of current efficiency on it is relatively small; in my opinion, it’s difficult to quantify this effect.
This post was last edited by w82464953 on 2013-5-10 17:42. There is latency in the WLAN connection, which has caused repeated posting; please forgive this.
With higher current efficiency, more alkali is produced; accordingly, more water in the feed alkali is consumed, so more water needs to be added.