Repair of ion-exchange membrane electrolyzers

Jiangyin Ankait Electrochemical Equipment Co., Ltd. is capable of carrying out repairs.

The repair process for ion membrane electrolyzers includes pressure testing, leak testing, cleaning, and patching. There are two coating application methods: electrostatic spraying and roll coating. Pressure testing and leak testing are crucial during the repair process, as these methods affect the electrochemical properties of the electrodes. It is known that Jiangyin Mierke uses electrostatic spraying, while Jiangyin Hongze and Ankete use roll coating.

Which household’s electrolyzer has been repaired? How is it working?

You can go to companies such as Jiangyin Mi’erke, Jiangyin Hongze, and Ankait to see what capabilities they have in terms of restoration; I’ve heard that Shanghai Chlor-Alkali has carried out restoration work before.

As far as I know, there are several companies in the Jiangyin area of Jiangsu that specialize in repairing ion membrane cells, and each of them has its own technical strengths. Jiangyin Ankait: We bring coating technology to Japan, and we have a technical partnership with Japanese company Daiso. There are also many companies that have received maintenance services from us, such as Shanghai Chlor-Alkali and Jiangdong Chemical, among others. The application methods are hand painting and roller coating. Jiangyin Hongze: The coating technology comes from Beihua Machinery; companies that have had it repaired include Shanghai Chlor-Alkali and Xi’an Xihua, among others. The application methods include hand painting and roller coating. Jiangyin Milk: The coating technology comes in part from the original Dinola, as some of its employees are those who stayed from the former Jiangyin Dinola, but it lacks core technical capabilities. In fact, in the domestic market for the repair of ion exchange membranes, as one person mentioned above, there are several methods of application such as manual coating, roller coating, and electrostatic spraying. However, in reality, aside from Beihua Machinery, most other companies use manual coating. Let’s first analyze the advantages and disadvantages of several coating methods: Roll coating: Advantage: Even coating. Disadvantage: If electrodes are not produced on a large scale, the loss of coating material is significant, reaching 15%–25%. Therefore, this method is generally not used for small-scale production; otherwise, the cost of the wasted materials would eliminate any profit margin for the company. Electrostatic spraying: even coating. Disadvantage: Since ion membrane electrodes are mesh-like in structure, and during electrostatic spraying it is necessary to convert the precious metals into an ionic state, significant losses occur – typically around 25% to 35% – as a result of which the actual amount of precious metals on the mesh decreases. Manual application: The amount of coating solution and the quantity of precious metals are easy to control. Disadvantage: The uniformity is slightly inferior, but as long as proper control is exercised during application, the uniformity can still meet the standards. In fact, for manufacturers, it doesn’t matter which painting method is used; what’s important is to rely on data and the actual performance of the product. What affects the performance is not the method of application, but the formula of the coating solution.

Our company has previously had business in this area with Beihua Machinery, but it turned out to be uneconomical due to cost issues. Apart from replacing the pole faces, some minor repairs are carried out by argon arc welders we train in-house. In the past two years, the volume of domestic business has surged; it is necessary for the original poster to investigate whether Beihua Machinery is still capable of taking on such projects, and whether it can ensure the quality of maintenance work once such projects are undertaken.

In fact, Beihua Machinery is unable to carry out routine repairs on electrolytic cells, as there are many uncertainties involved in such repairs; in particular, leak testing is the most troublesome task, requiring a lot of manpower and resources. Moreover, the cost of repairs cannot be too high. Therefore, for electrolyzers that are difficult to repair, Beihua Machinery generally recommends replacing them with new ones, which is unacceptable for ordinary manufacturers. Using the manufacturer’s in-house trained TIG welders is indeed a good option; simple tasks such as repairing nets can be handled by them, while more specialized tasks like fixing leaks or replacing nets are best left to professional repair shops. This post was last edited by limingshuguang on 2007-12-17 11:27.]

We have also encountered similar problems. However, Beihua Ji said that if someone else carries out the repairs, they cannot guarantee the lifespan of the anode and cathode of the electrolyzer (it’s stated in the contract). Moreover, if it is repaired by someone else, Beihua Ji will not offer further repairs – it’s quite a contradiction. :L

Jiangyin Milk’s coating process is indeed electrostatic spraying; no manual or roller-coating tools can be seen at the production site. If you don’t believe it, you can go there for a firsthand inspection. Their technology is basically based on that of Dinola, as are their workers, but they have a set of specialized testing equipment for checking coatings that is not known to others.

I have been involved in the repair of small monopolar slot anode plates. At that time, Beihua Machine and the Anti-Corrosion Institute of the Chinese Academy of Sciences in Shenyang were the two main options considered. Based on the repaired plates, Beihua Machine’s surface preparation process caused more damage to the substrate, while the method used by the Anti-Corrosion Institute was better. Compared to new anode plates, the voltage of the repaired anode plates increased slightly, with those repaired using the Shenyang method showing a slightly better result. It was ten years ago; I hope this can be helpful.

When performing repairs, electrode repair manufacturers determine the coating formula based on their requirements regarding the electrochemical properties of the repaired electrodes. For example, if a low chlorination potential is desired, less iridium is included in the formula; this will indeed reduce the chlorination potential, but it will also cause the oxygen evolution potential to decrease, resulting in a relatively high oxygen content in the chlorine produced； Some units require a high oxygen evolution potential; to achieve this, more iridium and other elements must be added to the coating formula, which in turn causes the chlorine evolution potential to rise, resulting in a relatively higher voltage once the system is put into operation. The industry has now begun to pay attention to the oxygen evolution potential. This post was last edited by limingshuguang on 2007-12-17 16:43.]