Problems in the practical application of heat exchangers
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We built a heat exchanger to recover steam heat for heating water; the water flows on the tube side while the steam flows on the shell side, in counterflow. There are no errors during software operation, but in practical use, the temperature at the outlet head on the cold side is already above 100 degrees, and there is significant noise in the pipelines on that side; it is presumed that the water there has turned into steam. Imagine that to solve this problem, the medium is replaced with flow in the same direction. Let’s all discuss together the reasons behind this situation and possible solutions.
What are the steam parameters of the poster? Switching to flow in the same direction should have a certain effect; considering increasing the water flow rate or reducing the length of the heat exchanger circuit are also options
The flow rate of the cooling water should be increased to lower the water temperature. Did the original poster take into account the temperature rise of the cooling water when making calculations? What is the maximum temperature it can reach?
Steam flow rate: 5.09 kg/s, inlet temperature: 165 degrees, temperature after complete condensation: 90 degrees； Water side flow rate: 70 kg/s; outlet flow rate at 85 degrees: 70 kg/s
If it’s not possible to increase the cooling water volume for now, it’s advisable to add a bypass wire and keep it slightly open during operation
In my opinion, the main solution should be to increase the amount of cooling water, or reduce the amount of steam – in other words, to align heat release and heat absorption. Other methods cannot change the fundamentals
I did some rough calculations: if the water inlet is at room temperature, 8.5 kg/s of steam is required to heat it to 85 degrees. A volume of 5.09 kg/s of steam is not sufficient to vaporize the water. There are two possible reasons for this: 1. The actual amount of steam needed is higher. 2. The actual water volume is small.
What was said on floor 7 is great! Adjusting the actual amount of steam and water will completely solve the problem
We encountered the same problem; we added a vent valve later, but it didn’t have much effect. The noise was caused by air hammer phenomenon. Could it be that the pump’s suction lift is not sufficient?
Adjusting the flow rate can certainly reduce air hammer, but the water temperature will not increase.
There must be an issue with the parameters; the reason was explained clearly on the 7th floor. Using counterflow heat exchange results in a worse performance – it can only prevent water from turning into steam. The problem needs to be addressed at its source; it’s likely that the amount of steam is too high and there is overheating, which leads to insufficient heat exchange area. It is necessary to increase the water flow rate and install a drain valve before the steam inlet.
Increasing the convective heat transfer is very effective
Thank you all for your feedback; I also feel that there might be inaccuracies in the actual implementation.
I agree with your view, but I’ve encountered situations where there was uneven mixing on the cooling water side – despite the calculations showing no problems, the actual cooling water temperatures differed by several dozen degrees before mixing occurred.