A method for determining tube leakage inside an evaporation condenser

This post was last edited by Xieshui on 2010-4-14 at 18:43. It is a low-pressure device, and the corrosivity of the medium is not high; therefore, the probability of leakage under normal conditions is very low. However, if the material used for the device is of poor quality, if the manufacturing process is inadequate, or if the quality of the circulating water is poor, leakage may still occur. Once leakage happens, it can be difficult to detect, especially when there are few monitoring procedures in place, as it does not affect urea production or even may lead to an increase in output. If leakage does occur, such phenomena might appear: changes in the conductivity of the waste liquid, changes in the liquid level in the tank (when the leakage is severe), and changes in the composition of the process condensate (which can be detected by analyzing the ammonia content on the shell side on a frequent basis). Chloride levels can be checked to confirm whether there is indeed leakage.

I agree with what Xishui Haiyou said earlier regarding equipment leaks: “It is a low-pressure device, and the medium it uses isn’t highly corrosive; therefore, the probability of leakage under normal circumstances is low. However, if the material used for the device is of poor quality, if its manufacture is sloppy, or if the quality of the circulating water is inadequate, leaks may still occur. Once a leak happens, it can be difficult to detect, especially when there are few monitoring procedures in place.” As for the latter part of his opinion, I think it is open to discussion. Firstly, the leakage of this circulating water will not affect production. Secondly, the phenomenon observed later on is one resulting from a leak in the positive-pressure equipment. Thirdly, the chloride level is high; I think it’s not a condensate tank but rather an ammonia storage tank. The reason for this is that the evaporation process is carried out under negative pressure (20–40 KPa, absolute). Regarding the original poster’s question, I would like to offer the following points for discussion and reference: Since evaporation takes place under negative pressure (20–40 KPa gauge), while the pressure of the circulating water is relatively high, at 0.4 MPa, which is the surface pressure, any leakage in this condenser will be apparent. When there is only a slight leak and no visible signs, it is difficult to detect; however, when tests for chlorides are conducted regularly in the ammonia storage tank, such leaks may be detected ； When there is a pressure difference: 1. Since the pressure of the circulating water in the tube side is higher than that in the shell side, especially when vacuum operation is used on the shell side, in the event of a leak in the equipment, the circulating water will leak into the process side, affecting the vacuum level. Under the same load and steam consumption, the liquid level in the ammonia storage tank as well as the corresponding monitoring temperature will change ； 2. Sample and analyze the liquid drain line of the condenser; chloride ions should be detected. The above two points are for reference only.

I agree with the two people above; testing for chlorides can confirm it. If a leak does occur, it must be dealt with promptly, as chloride ions can cause stress corrosion in the equipment, leading to serious consequences over time!

I agree with the opinion from the third floor: the shell side of the condenser is under negative pressure, so only cooling water will leak to the shell side. I’m not sure if all the teachers use the same process; in our case, the evaporated condensate from the first stage of the full-circulation aqueous solution method is stored in the chamber of the carbonammonium solution tank, not in the ammonia solution tank.

It is difficult to detect chloride ions in ammonia solution; by installing a sight glass below the liquid level, the problem can be easily resolved!

If an evaporation condenser has been in use for too long, pores may appear at the weld seams on the tube sheet. During normal operation, the amount of water circulating into the vacuum system is very small, making it difficult to determine this based on process parameters. If there is a chance for parking, after the evaporation system is filled with water, it can be inspected through the manhole on the head of the evaporation condenser or by opening the flanges of the inlet and outlet pipes, provided that the circulating water in the condenser can be stopped.

It’s generally not possible, but one can first test the chloride ions in the liquid coming out of a section of the evaporation condenser to see if it’s within normal ranges; if the level is high, then it’s very likely that…

8# 1668: The calcium ion level was measured at 60 mg/L; the chloride ion level was too high to be measured, exceeding a thousand

The apparent phenomena are a high liquid level in the ammonia tank, a higher resolution load than under normal conditions, normal resolution temperatures, etc., while the conductivity of the waste liquid keeps rising. On-site observation shows that more liquid is present under surface cooling compared to normal circumstances. In terms of design, each evaporative cooler is equipped with a liquid sampling point from which samples can be taken for analysis. Under normal conditions, no chloride ions are present in the sample, or only trace amounts are there. If chloride ions are detected in the sample and their concentration is on the rise, it can be inferred that there is a leak.

As long as the preceding section remains stable, if circulating water seeps in, the composition of the liquid exiting the condenser will change, with an increase in water content