“Discussion on “High Electric Density, Zero Electrode Distance Electrolyzers”
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This post was last edited by sunjl1981 on 2013-1-6 at 22:06. Recently I read an article titled \"Application of High Current Density Zero-Polar Distance Diaphragm Electrolyzers\", published in the 4th issue of \"China Chlor-Alkali\" in 2007. The article introduces the application of Asahi Kasei zero-gap electrolyzers at Tianjin Daguhua, and it clearly describes various data related to operational performance assessments; it is a highly practical article. Regarding the content of the article, I raised a question: what current density is appropriate for zero-gap cells. Zero-pole distance cells were introduced by electrolyzer manufacturers in order to \"reduce the voltage of individual cells and increase the output per cell.\" Cells with zero-pole distance feature a low voltage per cell along with a high operating current density. Asahi Kasei, Chloro Engineering, Woody, and INOES all have them. Especially, it’s promoted a lot by the chlorine industry. His operating current density is always above 5000 A/m2. Asahi Kasei only has zero distance at Dagu and Shihezi. But in my opinion, a high current density is not necessarily a good thing; it’s a double-edged sword. In fact, the higher the current density, the lower the investment required for alkali production equipment. However, there is another issue: the higher the current density, the more impurities accumulate on the membrane, which leads to a faster decline in the membrane’s performance and a shorter lifespan – especially given China’s current level of saltwater operation practices. (There have been cases in our unit where drivers continued driving despite excessive levels of saltwater and iron.) Furthermore, the higher the electrical density, the faster the anode coating wears out. Therefore, I would like to ask everyone: what is an appropriate level for high electric density operation? ? I’d also like to hear from users who have high-density grooves. :victory: # + + . hcbbs
Electrolyzers with zero pole distance represent another direction for future development; given the current national trend toward energy savings and reduced consumption, such electrolyzers can effectively lower the electricity consumption per ton of alkali produced. However, the challenge faced by domestic chlor-alkali manufacturers at present is that once they invest ； Second use. As mentioned above, cells with zero gap require higher standards in terms of operation; improper handling can lead to significant problems. As for what the original poster said, namely that the higher the electrical density, the faster the anode coating wears out, I disagree with this view. The anode coating used in cells with zero electrode spacing is different from that used in cells with high electrical densities today, and it is fully capable of meeting the required standards.
I have been to Xinjiang Zhongtai Chemical; they are currently using natural-circulation cells from Chlorine Engineering with a high current density of zero pole distance, with a current level of 5000 A/m2, and the maximum current that can be achieved is 16400 A. The electrical efficiency is over 98%, and the operation is very stable. The cells are equipped with numerous safety mechanisms to protect the membrane, and no accidents have occurred over the years. The membrane is DuPont F8020.
“I have been to Xinjiang Zhongtai Chemical; they are currently using natural-circulation cells from Chlorine Engineering with a high current density of zero pole distance, with a current level of 5000 A/m2, and the maximum current that can be achieved is 16400 A. The electrical efficiency is over 98%, and the operation is very stable. The cells are equipped with numerous safety mechanisms to protect the membrane, and no accidents have occurred over the years. The membrane is DuPont F8020. “ F-8020 is Asahi Glass’ Fulaimiao, while the current mainstream DuPont membrane is N-966
F8020 is a Asahi Glass film. Chlorine Engineering has just introduced the zero-gap cell n-BITAC.
Chlorine Engineering has been offering zero-gap technology for some time now. Its partner, Toyo Soda, conducted experimental tests on n-BiTAC at a high current density of 8 kA/m2 in 2002, and in 2004 it carried out continuous operations using n-BiTAC at the same high current density while also evaluating the performance of the electrolyzers； The first set of commercial electrolyzers was put into operation in Thailand in 2005, and n-BiTAC was introduced to China in 2007. The n-BiTAC used in chlorine engineering adopts a zero pole distance; the electric density is different from that of BiTAC. In China, a value of 5.5 or higher is generally recommended, and if the quality of the saltwater is good, a value of 6.0 or higher is also quite feasible. In my opinion, the main reason restricting electrical density at present is the quality issue of the saline.
The grooves are all good ones, so why is the performance poor once they are used in China? I believe that before launching a new ion membrane project, manufacturers first consider whether the skill level of your technical staff is sufficient, and more importantly, whether the operational skills of your front-line workers are adequate. Otherwise, even the most advanced process equipment is of no use. It can also drive you to the brink! Keep in mind: talent comes first!
The Asahi Kasei high-density, zero-gap natural circulation tanks used at Tianjin Daguhua operate well, saving approximately 120 kWh of electricity per ton of alkali compared to ordinary high-density natural circulation tanks. The economic benefits are considerable, though the operation is a bit more complicated than that of ordinary electrolyzers.
We used the high-electric-density natural-circulation polarizing tanks manufactured by Beihua Machinery, with the current set at 13.5 KA (the normal operating current being 12.4 KA), which corresponds to an electric density of 5.0 KA per square meter. It has been running for almost a year now, and it is functioning properly; however, specific details cannot be disclosed. But the risks are indeed high; after all, it has only been 1 year so far. Whether this will lead to an accelerated wear of the anode coating and a reduced lifespan of the coating cannot be determined at this point, although there is no upward trend in voltage at present.
Our company uses Asahi Kasei electrolyzers, with a current level of 13.5 KA/M2. They have been in use for only 10 months now. May I ask everyone, what is the normal voltage level for these electrolyzers? I used to work in diaphragm caustic production. Thank you. This post was last edited by yzhms on 2008-6-8 07:33]
A zero-gap cell is an inevitable development. Primarily, the internal structure of the cathode and anode needs to be scientifically designed; the chlorine and hydrogen gases produced by electrolysis must be released in a timely manner, otherwise the cell voltage will not drop. Additionally, the membrane’s performance needs to be stable, and the quality of the brine must be high; if the membrane’s permeability decreases, it creates problems for the electrolyzer.