Is scaling the only reason for the small temperature difference between the inlet and outlet water of the seal oil cooler? !
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This post was last edited by blade_wzy on 2015-12-11 at 13:22. The situation is as follows: A high-speed pump uses a Plan53B sealing and flushing scheme. The seal oil cooler (seal oil tank) is of the coil type, with circulating cooling water in the tube side and seal oil – 10# white oil – in the shell side. It has now been found that the temperature of the seal oil has suddenly risen to 70 degrees, whereas it was in the 50s before; moreover, the temperature difference between the inlet and outlet water is very small, at only about 5 degrees (with the inlet water at 26 degrees). Is this situation caused by a uniform layer of scale forming on the inner wall of the coil, resulting in poor heat exchange efficiency? ! Since the cooling water pipelines have been checked now, both the inlet and outlet streams seem to be unobstructed. The blades of the flow indicator at the outlet are also rotating rapidly in the correct direction, which indicates that there are no issues with the pressure difference, and the flow rate is certainly sufficient. There were also suspicions that there might be a problem with the oil pipeline system, such as increased wear of seals or blockages in the seal oil pipelines. But even if such issues led to poor circulation of the seal oil, it shouldn’t affect the cooling of the oil in the seal oil tank. And insufficient heat exchange capacity should only increase the temperature difference between the inlet and outlet water, not decrease it. So is the only possibility that the cooling water pipeline is scaled but not blocked? It’s quite troublesome now, as this cooler is welded together as a single unit, and it’s not possible to inspect the inside of the coil. Is there any good solution?
I’m not sure if chemical cleaning will work.
“The seal oil cooler (seal oil tank) is of the coil type, with circulating cooling water in the tube side and seal oil in the shell side. 1. Isn’t this reversed? The 53B system is generally designed for high pressure; isn’t it more reasonable for the seal oil to flow in the tube side?； 2. The cooling water is usually recycled water, and if it is not clean, scaling occurs very easily ； 3. If the water flows through the tube side, it no longer matters whether the cooler can be disassembled, because scaling occurs inside the tubes ； 3. Consult the manufacturer of the 53B system to find out how to clean scale with such a design
1. You’re right; indeed, in 53B, it’s more common for oil to flow through the tube side and water to flow through the shell side. This sealing and flushing system was custom-designed by the pump factory. The reason for this design is that the mechanical seal generates excessive heat under operation, and the amount of oil flowing through the tube side is insufficient; therefore, the oil flows through the shell side instead. I’m not a professional design manufacturer, so I don’t understand either. 2. The reason for wanting to remove the coil is that its volume is at least much smaller, and there are more options for dealing with it after removal. Now, to disassemble the integrated unit, it’s necessary to take down the sealed tank, which is nearly as tall as a person – which is extremely troublesome. As a result, it’s necessary to handle the issue on site, and the available solutions are limited. 3. After consulting the manufacturer, it is recommended to use water or gas with high pressure for purging, or to employ chemical cleaning. But now the pressure at the inlet of the circulating water is already 5 kilograms. I tried increasing the pressure using a valve at the outlet, but it didn’t work either; the pressure achieved with compressed air on site is only around 7 or 8 kilograms, which seems not to be effective at all.