Seeking help regarding the level gauge in the propylene tank area
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There is a level gauge of the magnetic flap type installed on-site; the magnetic flaps transmit signals to the DCS system. At 11:40 a.m., the liquid level dropped from 7.20 meters to 4.00 meters. The temperature today is between 12 and 26 degrees Celsius, in Zhejiang Province. There are no other abnormal issues. Could it be the temperature that is causing vaporization inside? Some expert advice would be appreciated
At both ends of the magnetic flap, the upper side is the gas phase while the lower side is the liquid phase
At 10 degrees, the specific gravity of propylene is approximately 0.52, while at 26 degrees it is around 0.5; with constant pressure, there are only minor changes. Possible reasons for the drop in liquid level could be (1) issues with the remote transmission signal. The person in charge should check whether the reading matches that of the magnetic level indicator on site; if not, the cause should be investigated. (2) Due to the increase in temperature and partial vaporization, the liquid level gauge shows a false liquid level. The reason is that propylene contains gas, which reduces the density of the liquid; as a result, the buoyant force is not sufficient to support the weight of the float. Put the level gauge down and try again. (3) The weight of the float is inappropriate; it is too heavy. Using the specific gravity of propylene (0.5), and assuming that two-thirds of the buoyant sphere is below the liquid surface, the weight of the buoyant body is calculated as G = buoyant force = 0.5 × (2/3)V = 1/3V. In other words, it is appropriate for the weight of the float to be around one-third of its volume; if it is too heavy, the lower specific gravity resulting from rising temperatures may prevent it from floating. The testing method is simple: measure the volume using a measuring cylinder and then weigh it. (4) Type of float: one type is fully sealed and pressure-resistant, while the other has a balance vent on top. Check; if it is the latter type, liquid propylene may have entered inside the float. (5) The magnetic force of the float is insufficient; the movement of the float does not drive the flap. It shows false (6) The level gauge is leaking air
:lol Agree with the previous comment
We have ruled out problems with the pipeline. Let me think; it’s probably what friend zhangyong6404 mentioned. As for the second reason, that’s what I think as well, but the decrease in pressure is due to vaporization of the liquid phase below, right?
Propylene is a flammable and toxic substance; it is necessary to first check for any leaks, and toxic gas transmitters should be installed near the storage tanks. If there are no leaks in the tank and the liquid level suddenly drops from 7.2 meters to 4 meters, there is only one possible explanation: the liquid level was originally at 4 meters, the float got stuck at 7.2 meters, and then, due to its own weight, it dropped back to the normal level of 4 meters.
What was said upstairs makes sense, but vaporization won’t have a significant impact, unless there is a large temperature difference – and such a large difference isn’t likely to occur, so this possibility can be ruled out. It’s possible that the liquid level of over 7 meters is an artificial reading; in other words, the float is stuck. This happens because the level gauge has been in use for a long time and there is dirt inside the pipes. We can therefore remove the liquid from within the pipes and determine the actual level again, to see if it is indeed around 4 meters.
It is recommended to install a level gauge that uses a different measurement method on the tank, such as a steel strip level gauge, a servo level gauge, or a magnetostrictive level gauge, so that the readings from these devices can be used as a reference for each other!
The level gauge should be cleaned regularly; vaporization is unlikely to occur. The liquid level indicated by the float may fluctuate, dropping suddenly by 3 meters – in such cases, there is a greater possibility that the float will get stuck! If it gets stuck, based on what’s in front, the liquid level indicator there should also show a maximum level of 7.2 meters; the original poster can analyze the reasons from within!
The Wo-2000 external ultrasonic level gauge is not affected by the temperature, pressure of the medium, or fogging; it enables completely contactless level measurement with an accuracy of up to 5 mm. It is currently the most accurate level gauge available, aside from those that use radiation. On-site measurement demonstrations are also available upon request – please contact the manufacturer for more details. . . . . .