Heat exchanger issues in ammonia synthesis
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In our company, ammonia synthesis is carried out through parallel flow in two towers; the circulation volume in one tower is generally around 150,000 NM3/H, while that in the other tower is around 100,000 NM3/H. Currently, there are two water coolers in each of these systems, with similar heat exchange areas and capacities. However, the water cooler behind Tower 1 needs to be cleaned frequently due to the rapid rise in temperature after cooling – it usually needs to be cleaned 1 to 2 times a day (the quality of the circulating water in our company is not very good). In contrast, the water coolers in Tower 2 do not need to be cleaned as often. The masters said it’s because System 1 has a higher circulation volume, roughly 1.5 times higher than that of System 2. I would like to ask: In the two systems, the heat exchange area of the heat exchangers is the same, their sizes are similar as well, and the quality of the circulating water in the shell side is identical. It’s only because the amount of gas in the tube side differs that the circulating water in the shell side of the water cooler in System 1 often gets scaled, right?
The reason is that differences in heat transfer amounts lead to varying temperature differences in heat transfer within the heat exchanger, and temperature has a significant impact on the formation of scale； It is recommended to use an evaporation condenser, which will solve your problem
Could you tell me what the temperature rise of the cooling water used in these two towers is? Generally, scaling in cooling water occurs due to the precipitation of compounds formed by calcium and magnesium ions at high temperatures, or as a result of algae accumulation. If the temperature rise is similar, I don’t think the flow rate should be the determining factor for fouling accumulation. I’m not sure if I understand correctly; please discuss it in detail downstairs
The circulating water temperature in both towers is the same. The opinions of the two guys upstairs seem a bit different. If we go by what the guy on the third floor said, then why does only the water in system number 1 experience a rapid increase in temperature after cooling?
What was said on the second floor is probably correct; temperature does have a significant impact on scaling
Could you explain in detail why a difference in the volume of gas within the tube bank leads to a temperature difference in heat transfer within the heat exchanger? Are all heat exchangers like this? When there is a certain difference in the amount of gas within the tube bank, does this lead to scaling occurring more rapidly with the same circulating water?
What’s said on the second and third floors isn’t contradictory; what’s stated on the second floor is correct. In fact, the difference between these two devices lies in the amount of gas flow in the tube side – specifically, the greater the gas flow in the tube side, the lower the temperature increase of the water on the shell side. Scaling is closely related to temperature; lower temperatures result in less scaling. I’d like to ask the original poster: what’s the difference in gas flow between the tube sides of these two water-cooled systems?
Tower No. 1 has a high circulation rate, and as a result the heat load on the heat exchanger is high. When the flow rate of cooling water remains constant, the temperature rise will naturally be higher. The average temperature of the circulating cooling water is high, and the solubility of salts such as calcium and magnesium, which tend to cause scaling, decreases as temperature rises. Therefore, a higher temperature of the circulating water leads to an increased tendency for scaling； Based on the phenomenon described by the poster, the actual heat loads of the two heat exchangers must differ significantly for such a phenomenon to occur.