The boiler water becomes highly acidic
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This post was last edited by Chemical Gas Purification on 2010-8-15 at 14:46. Our company’s 200,000-ton synthetic ammonia production system has been experiencing strange problems in recent days: the deionized water coming from the deionization station has a pH of 7–8 (as usual). After adding NaOH to it in the deoxidation tank (using the same amount as usual), the pH at the exit of the deoxidation tank is 9–11, which is within the specified range. But after entering the conversion reactor and the synthesis reactor, problems arose. Over several days, the pH of the water in the synthesis waste boiler and the conversion waste boiler dropped to 3.5, but the pH of the steam remained around 10, which is within the specified range. Our company increased the amount of NaOH added (by 5 times the usual amount); after 3 days, the pH of the conversion reactor was adjusted to 11, but the pH of the synthesis reactor remained at 6.5. After reducing the amount of chemical added, the pH of the synthesis reactor gradually decreased again, and the water in it was more turbid (yellowish in color). It’s not clear whether there is a problem with the water treatment plant. This problem has been bothering me for days; I wonder if any colleagues have encountered a similar issue. I would be extremely grateful
Reply to 1# PhantomWithMadness: It is likely that acid from the desalination treatment device has leaked into the desalinated water. From what you’ve described, it can be seen that the boiler water is cloudy and yellowish, which indicates that the boiler has been corroded. We have also encountered situations where the pH level of the boiler water dropped to 4.0, but we were able to identify the cause quickly.
It’s obviously a problem with the water treatment station; what was said upstairs is correct – acid has gotten in.
1. Tell the person on the 2nd floor, 2. Check the chemical addition
According to the procedure, check each device one by one. I hope the original poster can find the reason soon.
Thank you to everyone above; the probability of acid leakage is very low, as the pH value of the feed water is normal, and so is the pH value of the deoxygenated water. It’s only the pH value of the boiler water that drops to around 3. I believe that strongly acidic cation exchange resin has leaked into the desalinated water; at low temperatures it does not exhibit acidity, but once it enters the steam drum, it undergoes hydrolysis at high temperatures and becomes highly acidic. But the boilers with another nitric acid system using *water did not experience such problems; the water source was the same, Alas! We can only check them one by one!
Reply to 6# PhantomWithMadness: There is some validity to the idea of resin leakage, but there isn’t any evidence regarding decomposition due to heat; this should be investigated further.
If it is suspected that resin has leaked into the deionized water, causing the boiler water to become acidic due to decomposition at high temperatures, samples of water from the same batch can be taken for testing. This will determine whether the water quality in the laboratory, under conditions of constant pressure and high temperature, matches the pH of the boiler water; if they do not match, other causes can be investigated. I’m wondering if an alkaline substance has leaked into the boiler water, causing the salts in it to undergo hydrolysis and produce phosphoric acid.
Check where the inter-stage condensate water from the carbon dioxide compressor is being recycled to
My company seems to have identified the reason mentioned by the original poster; it’s caused by leakage of circulating cooling water. As for the underlying mechanism, I’m not quite sure yet
I have a strong feeling that you work at our factory! ! The reason has been found!