Methods for determining if a heat exchanger is leaking and solutions to the problem
Thread Content
This is how we proceed during the design process: 1: Install sight glasses at both ends of the heat exchanger, close the inlet, and open the outlet. After a few minutes, check whether any liquid is flowing out; if it’s a non-water-based liquid, oil, or a colored liquid, it can be seen immediately. 2: Install a pressure gauge suitable for the relevant pressure range at 0.5 meters before the inlet of the heat exchanger and at 0.5 meters after its outlet. If the readings of the two gauges are identical or differ by only the rated value (due to height differences), it indicates that there is no leakage; otherwise, there is a leak. 3: Use accurate flow meters, one at each end, and interlock them with the data from the DCS system. When the readings from both meters match, normal operation proceeds; when they do not match, the alarm system is activated. This is then interlocked with the electric control valve (or pneumatic valve), which is used to close the liquid inlet. Timely control has been achieved.
This approach is too complicated, and the investment required is high. The simplest solution is to install a sampling valve at each of the inlet and outlet ports of the heat exchanger, so that samples can be taken at regular intervals; generally, the heat exchange media are different from one another.
OP, your investment is too large; it’s likely that this method isn’t cost-effective, and few people will adopt it. Simple method: 1. Completely close the inlet and outlet valves of the tube side or shell side, and drain all the material through the drain valve at the lowest point. If it’s not possible to drain everything, determine whether the material belongs to the tube side or the shell side, and then make a judgment ； 2. If under negative pressure, a pressure gauge can be installed on the drain valve to make a judgment ； 3. Make a judgment by analyzing the material in the tube side or shell side.
Is the LZ design feasible? 1. It becomes difficult to make judgments when there is slight internal leakage in the valves. 2. Transmitter devices for pressure gauges are expensive, while it’s hard to get accurate readings locally. 3. The adjustment method requires significant investment. The most common approach is to take samples at regular intervals for analysis; in cases involving pH levels, test strips can be used for quick checks
Just shut off the inlet and outlet valves of the heat exchanger, take a sample through the drain valve for analysis – is it really necessary to go through such trouble?
The owner must have reaped quite a lot of benefits from this approach: lol
It’s scientific but not practical; it seems the original poster comes from a background in research and experimentation, and applying the methods used in the laboratory to engineering applications is inappropriate.
The best approach is to completely disable the analysis sampling for one of the flow paths (the tube side or the shell side), to see if the composition of the fluid in that path has changed.
Theoretically... in practice it probably won’t work well~ Method 1: When there is slight leakage, it’s not noticeable; if there is significant leakage, it will be detected through other means long before that~ Method 2: Meter deviation/leakage inside the valve~ Method 3: It’s normal for there to be differences between flow meters; controlling based on those deviations will cause frequent interruptions
There was a slight leak in the primary side stream oil of our plant’s atmospheric and vacuum distillation unit; crude oil seeped into the side stream oil. To maintain normal production, the pressure of the side-stream oil pump was increased, making it higher than the pressure of the feed oil so that it could leak into the feed. It can be said that this is also a temporary workaround
Our factory’s heat exchangers also have this problem: water flows in the tube side (pressure 0. 58MP, temperature 25°C–90°C); H2 and N2 gases are used in the shell side (pressure 0. 58MP, temperature range of 240°C to 120°C). The drain valve at the bottom of the shell side (DN20) is opened for a set period of time (one shift), and it is found that a large amount of water flows out – around 100 to 200 liters. The amount of condensate shouldn’t be this high; there might be an internal leak. What do you think, residents on floors 2, 3, and 4?