How to remove scale from plate heat exchangers
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The company has 2 stainless steel plate heat exchangers with a surface area of 20 square meters each. After being in use for about 2 years, their heat exchange efficiency has become very poor. Upon disassembly, it was found that the layer through which the circulating water flows was heavily covered with scale. Trying to remove this scale by soaking it in a descaling agent purchased from the market showed no effect. I would appreciate it if anyone could advise me on how to get rid of this scale. Thank you!
If the volume of work involved isn’t large, it can be handled manually: take some samples, dilute them with acid to test and adjust the acid concentration; the better if the concentration that can be achieved is low.
1. When the heat exchanger is scaled, it is necessary to take scale samples for dissolution tests; cleaning agents (organic or inorganic acids) are preferred. Common organic acids include oxalic acid, formic acid, etc； Inorganic acids mainly include hydrochloric acid, nitric acid, etc ； The cleaning temperature should be between 50-60°C for better cleaning results ； 2. If your company’s heat exchangers develop scale after just 2 years, resulting in poor heat exchange performance, it indicates that the water quality is prone to scaling. It is necessary to add some scale inhibitors to the circulating water, as this can effectively prevent scaling and significantly extend the service life of the heat exchangers. The use of scale and corrosion inhibitors is already quite common these days, so it is recommended that you consider doing so.
First, take a sample to analyze the composition of the dirt, and then select an appropriate cleaning agent to remove it. Use hydrochloric acid and nitric acid with caution, as it’s easy to cause leaks, which is not worth the risk. Adding scale inhibitors to the circulating water is a good approach, but if it’s only necessary for this heat exchanger and not for other areas, then it’s fine not to do so.
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