Plate heat exchanger leakage detection methods
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This post was last edited by wode*aohei on 2015-8-27 at 10:01. In our projects, plate heat exchangers are commonly used; since one side of the solution contains a high concentration of chloride ions, any leakage could contaminate the medium on the other side. I raised this issue during the meeting last night. At present, our idea is to monitor the pressure changes in both sides of the medium in order to detect leaks, but this method seems to work well only when there is a significant difference in pressure between the two sides. What about in cases where the leakage amount is small or the pressure difference is minimal? I’m thinking that it might be possible to detect leaks by measuring changes in chloride ion concentration. I would like to ask everyone here: are there any good methods for detecting leaks in engineering practices? Please suggest some solutions. Additionally, I have a question regarding the price of plate heat exchangers. My colleague obtained information from a manufacturer in Shanghai, stating that for the same operating conditions, the price of titanium alloy plate heat exchangers is similar to that of stainless steel 316L plate heat exchangers. The reason given is that stainless steel has a higher density than titanium, resulting in greater weight. I don’t think this makes much sense, as from what I know, when the heat exchange area is the same, titanium plates are much more expensive than 316L plates. Which piece of information is correct?
Titanium plate heat exchangers are much more expensive than stainless steel 316L
The prices are similar; the density of titanium is 4.51, while that of stainless steel is 8. The cost per unit of titanium plates is much higher than that of stainless steel plates
Measuring concentration seems quite difficult to me; measuring pressure is more reliable. Just like with flow rate, conventional methods can be used to detect leaks, as once there is a leak, chloride ions will enter the other side
There is a solution you can consider. One option is an online pH meter; this should be given priority. If testing is to be done on the steam side or the water side, it’s not possible to detect neutral salts or other neutral substances. Another option is an online conductivity meter, which can detect leaks of conductive ions; it can also detect chloride ions, and its sensitivity is quite good. In the event of a leak, the conductivity will increase by hundreds or even thousands of times. Of course, if financial conditions permit, it’s possible to install both devices simultaneously.
The “tracing” method can be employed: a trace amount of additive is added to the side containing chloride ions, and special instruments are used to measure its leakage to the other side.
It’s several times higher, I guess – the price per unit of titanium plates is high; you can’t calculate it based on density. Heat exchangers are definitely determined by their heat exchange area
Thank you all for your answers. However, based on what we’ve observed on site, the pressure on the other side is higher than that on the side with high concentrations of chloride ions. How can we detect leaks in such a situation?
It might be difficult to find truly effective testing methods, and by the time such methods are found, the product has already been contaminated. Here are two suggestions: 1. First is the use of double-plate heat exchangers, which are required by law in certain sectors in Europe to ensure that leaks do not cause contamination on the other side. In this case, if there is corrosion leakage, it will leak outside and can be easily detected. 2. Another approach is to use high-grade chloride-resistant materials, such as SMO254, 904L, etc. The material has to be determined based on the specific chloride ions and the specific medium. Ensure that the plate material does not corrode, and use thick plates, such as 0. 7 or 0. 8 millimeters thick