Is the water level indicated by the boiler drum level gauge consistent with the actual water level in the drum?
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This post was last edited by zgj2405 on 2011-7-6 17:35. Is the water level indicated by the boiler drum level gauge consistent with the actual water level inside the drum?
The steam drum and the level gauge can function as a communicating vessel, with equal pressure at the two liquid surfaces of this vessel. However, due to the heat dissipation from the level gauge itself and the water connection pipes, the water in the level gauge is at a lower temperature and has a higher density compared to the water in the boiler drum; as a result, the level indicated by the gauge is lower than the actual level in the boiler drum.
Due to the heat dissipation by the level gauge itself, the water temperature inside the level gauge is lower than that of the boiler water in the drum; as a result, the density of the water in the level gauge is higher, causing the actual water level in the drum to be 10% to 50% higher than the level indicated by the gauge. As the boiler pressure increases, the temperature of the water in the drum rises, leading to increased heat dissipation from the level gauge. This results in a greater temperature difference, and consequently a larger difference in water level. In boilers where the soda mixture enters below the drum water level, the density of the boiler water decreases due to the presence of bubbles in the drum water volume. As the salt content in the boiler water increases, the bubbles in the drum water volume rise more slowly, which also reduces the density of the water in the drum; as a result, the actual water level in the drum is higher than the level indicated by the gauge. The mixture of steam and water enters from the steam space of the drum, which helps to reduce the difference between the actual water level in the drum and the reading indicated by the gauge. For boilers under high pressure, in order to reduce the water level difference, measures such as insulating the gauge or adding a steam jacket to minimize heat loss from the gauge can be taken.
There is a slight difference, but not very large; if the difference were significant, the level gauge would need to be calibrated.
It’s different; both the remote level gauge and the on-site level gauge are located at a height higher than the bottom of the tank. When the level is at zero, there is still some actual liquid present.