How to select a liquid level gauge for LPG storage tanks
Thread Content
The LNG plant is equipped with LPG storage tanks A\B\C; the medium contained in these tanks is a mixture of hydrocarbons with a density of 0.67 g/cm3. Level measurement is carried out using Honeywell differential pressure transmitters. The height of each storage tank is 3.2 M, and the differential pressure range is 0–20.4 KPa. Previously, the central control system kept indicating inaccurate liquid levels. Upon on-site inspection, it was found that the differential pressure level gauge was installed 30 centimeters below the tank. After adjusting its zero point, the levels became accurate again, but after some time the readings became inaccurate once more. Subsequently, an on-site magnetic flap level gauge was installed for zero-point calibration; however, after it was in use for some time, a significant discrepancy emerged between the readings on site and those transmitted remotely. Later, tests of the liquid’s density by draining it revealed that the moisture content in the mixed hydrocarbons was too high, resulting in an uncontrolled density for these mixed hydrocarbons. The manager ordered a process modification and the purchase of reed switch level gauges for remote monitoring, but the magnetic float is still affected by density. I would like to ask experts about gauge selection – are there any other methods besides ultrasonic level gauges that can be used to accurately measure the liquid level in storage tanks? ? ? ? ? ? ? ?
The so-called liquid level can be divided into \"liquid surface level\" and \"liquid volume level\". If you want accuracy, which one do you mean? Refer to this post: https://bbs.hcbbs.com/thread-1391891-1-1.html.
Use a float-type device with a display range of 5-95% or 3-97%, and it outputs a 4-20mA current signal to the remote control box
Is it a magnetic float level gauge? The magnetic float is still affected by density, right?
The differential pressure is affected by density; pay attention to my question – what we are installing is the differential pressure
LPG systems generally use reed switches + glass plate level gauges, mainly due to cost and practicality considerations.
If there are large density variations, contact-type level gauges cannot be used; radar or ultrasonic level gauges can be chosen instead
The radar is used to determine the dielectric constant of LPG
Learned something new: handshake