What should be the iron content limit in the brine fed into the tank? ?
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This post was last edited by sunjl1981 on 2013-1-6 23:27. What should be the allowable iron content in the brine fed into a conventional ion-exchange membrane electrolyzer? ? As far as I know, it is generally kept below 0.5 mg/l, that is, below 500 PPb. On page 115 of the book \"Production Technology of Alkali by Ion-Exchange Membrane Process\" (Table 5-5), it is stated that in Asahi Kasei’s forced-circulation polarization cells, the iron content in the anode solution fed into the electrolyzer is less than 0.05 mg/l, which is roughly equivalent to below 50 PPb. As far as I know, the iron content in the brine fed into the ion exchange membranes by various manufacturers is kept at least below 300 PPb; I’m not sure whether any manufacturer is able to keep this level at 0.05 mg/l ? Is there an error in the description in the book? I hope experts in the chlor-alkali industry can help clarify this! ! Thank you so much! This post was last edited by yzhms on 2009-3-14 11:26 ] # ， ， &
Please refer to the relevant topic posts: http://bbs.hcbbs.com/viewthread.php?tid=129468&page=1#pid685621 http://bbs.hcbbs.com/viewthread.php?tid=85650&page=1#pid656490 http://bbs.hcbbs.com/thread-115257-1-1.html
Previously, our company kept iron levels within 50 PPb; later, since the FE level couldn’t be reduced to around 70 PPb, we changed the target to keeping it within 100 PPb. The requirement now is to keep it within 50 PPb. Last edited in this post by yzhms on 2009-3-14 11:26]
Yes, it is feasible to keep the iron content in pure salt water below 50PPb. Our company uses TP-208 resin, and the iron content in the salt water at the outlet of the resin tower is always below 50PPb. This post was last edited by yzhms on 2009-3-14 11:26]
Recently, the iron ion concentration in the brine entering our company’s resin tower was around 100 PPb, while that in the brine exiting the resin tower was about 80 PPB. The iron ion concentration in the brine entering the electrolyzer was approximately 400 PPB, and it was also around 400 PPB in the fresh water exiting the electrolyzer. The resin tower’s effectiveness in removing iron ions is very poor; there is a large difference in the iron ion concentration between the outlet of the resin tower and the inlet of the electrolyzer. The saltwater pipes connecting these two points are made of titanium. After adding some fresh water to the concentrated brine, the iron ion concentration increases significantly, and the iron ion concentration in the fresh water coming out of the electrolyzer is much higher than that in the concentrated brine. I wonder if anyone has encountered this problem before. This post was last edited by yzhms on 2009-3-14 11:28]
Have you considered the possibility that the lining of the valve is corroded? Some manufacturers have encountered such issues. Discussion is welcome.
For TP-208 resin, 50 PPb can be achieved. This post was last edited by yzhms on 2009-3-14 at 11:28.]
For the tanks used in chlorine production, the concentration of saltwater fed into them needs to be kept at 100 PPb. This post was last edited by yzhms on 2009-3-14 at 11:29.]
1. The currently accepted range is 50–100 PPb in secondary brine； 2. The requirement for membranes in Japan is generally below 50 PPb, which may be related to the structure of the membranes there; deposits tend to form more easily within such membranes ； 3. For DuPont membranes, deposits form on the surface, but this has no impact in the short term ； 4. With the use of refined salt, the impact on iron has gradually come to the attention of many; it may have an effect on electrodes, and further discussion is needed. This post was last edited by yzhms on 2009-3-14 11:29]
1. The typical requirement for the brine fed into the cell using Asahi Kasei’s Aciplex-F series membranes is an iron content of less than 50 PPb (in the case of anodic acidification); if no acid is used for anodization, this limit can be increased to around 1 ppm. 2. When signing contracts in China, Asahi Kasei may aim to meet their specified standards, which is why they have relatively strict requirements regarding metal ion levels; for example, our contract requires a level of less than 20 PPb. As far as I know, different manufacturers have varying requirements. 3. Aminophosphite resins are not sensitive to iron; this is probably a common observation among manufacturers such as Huashen, R&H, and BAYER. It is difficult to elute these substances after adsorption, and in the short term this does not have a significant impact on the resin’s adsorption capacity. However, it’s hard to say what will happen over the long term, as the exact mechanism behind this phenomenon is not well understood. 4. The effect of iron on the electrical efficiency and power consumption of ion exchange membranes has been discussed in many posts on this forum, so there is no need to go into further detail here. This post was last edited by yzhms on 2009-3-14 11:30]
It’s been incredibly beneficial! Thank you to all the seniors for their advice!