Ammonia synthesis system: internal leakage in the 210m2 intermediate vessel
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Waste heat boiler: Nominal diameter: φ1800/Φ2200; Type: Horizontal. Number of heat exchange tubes: φ24×5; Heat exchange area: Fzhong = 210 m2. Our factory’s waste heat boilers have been in use for two years; this year, there were two instances of leaks in the boiler’s internal tank. In the first incident, the liquid level in the tank was 40%, and there were multiple weld defects at the joints where the high-pressure gas pipes connected to the tank. The second incident occurred recently: after the adjustment made last time, the liquid level in the middle boiler was set at 60 percent. This time, a high-pressure gas pipe leaked, and a crack appeared at the base of the flange of the water jacket shell at the inlet of the middle boiler. Everyone, please help analyze the reasons. Thank you
It is best to ask the boiler inspection agency to conduct an inspection to determine whether there are any issues with the welding materials or the material of the tube sheet. What pH level do you maintain for the boiler water on a regular basis? How much phosphate should be controlled? If the indicator control is fine, it might be a problem with the material.
Leaks from waste boilers in ammonia synthesis production pose significant safety risks; severe leaks can easily lead to major accidents； Mainly: 1. Material issues; the problems with several old boilers from the 1990s were mostly due to material defects ； 2. Equipment processing techniques and construction quality issues such as electrode types, heat treatment methods, welding techniques, etc ； 3. Various factors such as usage conditions also have a certain impact.
First, one needs to check whether the various indicators under control are appropriate; secondly, there is the issue of equipment manufacturing
I think it’s due to design reasons. Although I don’t know what type of waste heat boiler your factory uses, the ones I’ve seen from Zhongguo No.1 Boiler Factory have a conventional tube-type structure. If it’s this kind of structure, I believe it’s necessary to take into account the significant temperature fluctuations at the water addition point; in terms of engineering design, a boiler with a gas holder can be used. This not only helps to address the issue of large temperature variations at the water addition point but also ensures that there is sufficient space for steam and water separation, thereby extending the service life of the equipment and pipelines. As for using more advanced materials, I haven’t studied that option, but I think it would likely not be cost-effective. I appreciate any advice you can offer.
If there are no issues with the operation, it is most likely a material problem.
It is best to keep the liquid level high, so that the heat exchange tubes are submerged in water; heat transfer then takes place through the vaporization of water. If the liquid level is low, more heat exchange tubes remain uncovered by water, and this situation is equivalent to \"dry burning,\" which causes severe damage to those tubes. Additionally, the area at the interface between water and vapor is a region with high ion concentrations, which can easily lead to electrochemical corrosion of the nearby heat exchange tubes.
It’s most likely a material issue; also check if there are any problems with the water quality