New approaches to solving scaling on the circulating water side of heat exchangers
Thread Content
This post was last edited by Peng Yongqing on 2026-1-15 at 13:46. The circulating water in industrial enterprises sometimes has a high calcium hardness, reaching 400, 500, 600 or even higher. The higher the calcium hardness, the greater the risk of scaling in heat exchangers, which leads to a decrease in heat transfer efficiency and increased energy consumption for the enterprise. Common solutions: First, perform a one-time cleaning during the annual maintenance. Although this method is feasible, it does not address the issue of scaling that occurs during production, nor does it help reduce energy consumption during production. II. Consider installing specialized scale prevention and removal equipment in front of individual heat exchanger units, such as microwave-based scale prevention and removal devices, to prevent, inhibit, and reduce scaling in the heat exchangers through online operation of these devices. Today, I would like to propose another approach: rather than simply addressing the scaling issue in a particular heat exchanger, it is about finding ways to reduce the overall scaling level throughout the circulating water system. In other words, it is about minimizing scaling on the circulating water side of all heat exchangers in the circulating water system. The method is as follows: Install microwave scale inhibition and removal equipment on the main circulating water pipeline; note that it should be installed on the main pipeline, not on a branch pipeline where a separate device is located. Mechanism of action: Microwave scale inhibition and removal equipment uses microwaves and alternating magnetic fields to act on the circulating water in the main pipes, facilitating collisions between calcium ions and carbonate ions in the water, thereby forming calcium carbonate microcrystals. These microcrystals are relatively small, generally at the nanoscale, and form a loose aragonite scale that remains suspended in the circulating water. These microcrystals continuously circulate along with the circulating water, serving two purposes: first, they act as seed crystals, promoting the deposition of calcium carbonate ions from the circulating water onto these microcrystals rather than on the heat exchanger; this reduces the amount of scaling on the heat exchanger. Second, during the circulation process, it continuously washes the surface of the heat exchanger, breaking down the scale inside it. For enterprises with high calcium hardness in their circulating water, I think this approach is worth trying; the return on investment should be much higher than the cost of investment. Especially for enterprises with high steam consumption, this method can be used to save energy and reduce consumption.
Thank you for sharing the information; the forum is even better with you here.
I think it’s simpler to just add sulfuric acid directly. The formation of calcium sulfate precipitate reduces calcium ions while stabilizing the pH value.
Adding sulfuric acid is one method, but using too much of it is not good either; it may lead to too low an alkalinity that causes corrosion, and calcium sulfate scale may also form.
If I’m not sure, I’ll ask. It seems to be installed on the water supply pipe; but could this lead to accumulation inside the pipe walls? After all, those surfaces aren’t smooth, and rust can also occur. Are any techniques used?
Some microcrystals will gradually settle in areas where the water flow is slow, but this sedimentation is rather loose and can be carried away by the water flow, so it does not cause blockages.
Don’t add too much. The pH is controlled at 8-9, breaking down HCO3- ions to form calcium sulfate and calcium carbonate crystals, which are then filtered out. I used to work at a sulfuric acid plant, where sulfuric acid was added to circulation tanks; the water in those tanks was crystal clear, with no issues related to scaling or corrosion.
When sulfuric acid is added, it cannot be used in large quantities due to the need to control the pH value; therefore, the amount of calcium carbonate that can be produced may be limited. If the water quality is poor, it may not solve the fundamental problem.
By controlling the pH value, the HCO3- ions are naturally destroyed, and the Ca and Mg ions precipitate. I’m not sure what you mean by poor water quality
If I don’t understand, I’ll ask – this is one approach, but it’s necessary to treat different types of heat exchangers differently. For example, in the case of shell-and-tube heat exchangers where water flows through the shell, there are many dead corners; scale that forms in the main pipelines can be hindered by these dead corners and tube bundles, leading to uneven distribution of the cleaning agent and ineffective scouring. Therefore, it seems that this method is only suitable for heat exchangers with smooth surfaces, few dead corners, minimal obstructions, and high flow rates.