Technical help: What causes this scale?
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This post was last edited by hesonchang214 on 2011-6-28 at 16:37. Hello everyone, regarding shell and tube heat exchangers, there are spots in the pipes that resemble weld slag; they are black in color and insoluble in acids. The water used for rehydration is tailings water; it undergoes polyaluminum coagulation, polyacrylamide flocculation, oil removal, and then is recycled. Excuse me, what is this black substance? What caused it? How to eliminate it?
This post was last edited by cdpulin on 2011-6-10 09:33 to remove it? It’s simple: install a fully automatic filter on the pipeline.
Reply to 2#: The long bow is too expensive and not suitable; it’s from a small factory. Moreover, that approach only provides temporary relief rather than a permanent solution. Is there a better way?
Is it attached to the pipe, or is it a product resulting from the bonding with the material of the pipe’s inner wall? What material is a shell and tube heat exchanger made of? If it is merely an attachment, it may be due to the PAM in the water not having settled completely into the circulation system; it adheres to this area after passing through the heat exchanger, and then forms as a result of high-temperature oxidation.
Reply to 4# cdpulin: It is made of carbon steel and attaches to the pipe wall. Additionally, we add chemicals manually in one go, which results in uneven distribution of the chemicals
I disagree with the above view! I have encountered such situations; it’s caused by your PAC. If the PAC you use has low purity, it will contain impurities, and that’s what happens over time as you mentioned. It is recommended to change the manufacturer, or using a liquid solution can resolve the issue.
It might be due to residual chemicals that have adhered to the walls of the heat exchanger; it could also be caused by impurities such as coal ash. The water you use for make-up is tailing water, which contains a high level of minerals, and when flocculation and sedimentation are not complete, these substances end up entering the system. The reason should lie in the flocculation and sedimentation stage. Check the reason carefully.
Agree with what was said on the sixth floor; it is recommended to check the PAC.
Reply to 6# Yuruyu Yucheng: Isn’t liquid PAC prepared from solid forms? I think it comes from the components in the tailing water; a chemical reaction has taken place. Are you using this water as circulating cooling water? That’s too stingy
The reasons are complex; it’s better to provide detailed information on the treatment processes and water quality
Reply to 1# Ordinary Life: The substance you mentioned could be PAM in the water that has not settled completely, resulting from high temperatures.