Should the DC power consumption increase or decrease as the electric density rises?
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This post was last edited by sunjl1981 on 2013-1-6 at 23:31. I saw in the chlor-alkali section of HaiChuan Chemical that TianYa LangZi (wlntjs) replied to nanren2, stating that there is a relationship among electrical density, cell voltage, and power consumption; the people who commented above have already provided excellent explanations. Generally, the chlor-alkali industry standards define it as follows: for every 100 A/m2 increase or decrease in current density, the direct current consumption increases or decreases by 14 kwh per ton of 100% NaOH. Similarly, this also affects the cell voltage by about 20 mv (assuming the electrical efficiency remains unchanged). I disagree with this view; in the book “Chlor-Alkali Processes,” it is stated that the impact of changes in current density on direct current consumption is as follows: an appropriate increase in current density. When the current density increases, the slot voltage also increases accordingly, but since the theoretical breakdown voltage does not increase with rising current density, the overvoltage increase is minimal. In other words, the slot voltage does not increase proportionally as the current density increases, but the output does increase proportionally with the increase in current density. Therefore, the consumption of electrical energy decreases accordingly. One view is that the DC power consumption increases as the electric density rises, while another is that it decreases as the current density increases. Which view is correct? I hope the leaders in the chlor-alkali industry can help clarify this for me; I thank them in advance! # ， ， &
As the current density increases, the theoretical decomposition voltage does not increase; however, the anode potential and cathode potential rise accordingly, leading to an increase in cell voltage. At the optimal current density, it follows the formula: V = V0 + KD.
Several aspects of the electrical energy consumption during the electrolysis process should be considered: electricity used for decomposition, electricity used for side reactions, circuit losses, conversion to heat energy, and so on. This post was last edited by yzhms on 2008-2-23 08:17.]
It depends on the stage; there is an optimal period for current density
There is a misunderstanding on the first floor regarding power consumption for alternating current and direct current. The power consumption for direct current is voltage/(1.492*current efficiency), while the power consumption for alternating current is the actual amount of electricity used divided by the amount of alkali produced. As the current density increases, the cell voltage rises, and accordingly the power consumption for direct current also increases; however, the power consumption for alternating current may not increase, provided that operation takes place within the optimal current density range (the limit current density). In such cases, the increase in electricity consumption due to the rise in cell voltage is less than or equal to the increase in alkali production, so the overall power consumption either remains unchanged or increases only slightly. Please carefully understand the similarities and differences between AC power consumption and DC power consumption upstairs.
What is asked on the 1st floor is simply the DC power consumption of the hydrazine hydrate! ! In my opinion, according to the formula W=actual cell voltage/(1.492×current efficiency), the actual DC power consumption depends only on the actual operating cell voltage, regardless of whether the operating current density increases or not – of course, this is assuming that the current efficiency remains constant. As the current density increases, the slot voltage definitely rises; it’s just that the degree of increase varies! As Brother yzhms said, when the current density exceeds 5 KA/M2, both the current density and the cell voltage slope increase. On the other hand, since the manufacturing standards for various electrolyzers vary, and especially due to the decline in performance over time, in some cases the current density may exceed 5 KA/M2, resulting in an increase in both the current density and the cell voltage slope; whereas in other cases, even a current density of just over 4 KA/M2 can lead to a significant increase in the cell voltage slope. In short: the DC power consumption per 100 units of lye in the electrolyzer depends only on the cell voltage, regardless of the factors that affect this voltage. Of course, if comprehensive economic benefits are to be considered, it is necessary to determine the optimal operating current density based on: total power consumption, the performance of one’s own electrolytic cells, total profit, and the cost per ton of caustic soda! ! ! ! The above are merely my personal opinions; I hope everyone can offer some guidance. To be honest, I have indeed learned a lot recently on the Chlor-Alkali section of HaiChuan Chemical, and I’ve received a lot of help from teachers and seniors. Here, I would like to thank all the technicians, moderators, instructors, and seniors from the chlor-alkali division of HaiChuan Chemical! ! Wishes for smooth work and all the best; may the Chlor-Alkali section of HaiChuan Chemical continue to thrive in the new year! ! !