What method is used for liquid level measurement in atmospheric pressure towers?
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Could everyone tell me what type of instrument is used to measure the liquid level in the atmospheric pressure tower at your facility? What brands are they? Are there two sets of measuring devices in total? What are the advantages and disadvantages of each? Let’s share some experience. . . .
It depends on your materials and the required precision; capacitive, differential pressure, radar level gauges, or servo level gauges can all be used. Differential pressure level gauges from E+H, Rosemount, and Yokogawa are all quite good
We have a negative-pressure tower here, and the liquid level at the bottom is measured in two ways: one with an on-site magnetostrictive level gauge, and another for remote monitoring, which seems to be from KT.
Liquid level measurement in atmospheric pressure towers: Medium: atmospheric pressure residue; operating temperature: 370 degrees. The required accuracy is 1.0. Does what was mentioned on the second floor refer to a double-flange differential pressure level gauge? Is the temperature suitable? Is the in-situ magnetostrictive level gauge mentioned on the third floor a type of external measurement? Since the medium tends to solidify, did you use steam for semi-heating or ordinary insulation?
The level gauges commonly used for some of the tower equipment in our installations are double-flange differential pressure transmitters from ROSEMOUNT; they are quite expensive, costing over 10,000 per unit. Radar level gauges and radio frequency admittance type level gauges are also used. For ordinary equipment, one gauge is sufficient ； However, for some important level gauges, they are designed with three or two units, using a two-out-of-three or one-out-of-two voting system.
Use a diaphragm-type double-flange differential pressure transmitter, a Rosemount product.
Additional note: At a temperature of 370 degrees, double flanges are not suitable; in such cases, the installation method using a regular differential pressure transmitter along with an isolator is preferred.
If measuring the water level, an immersion type level gauge can be used, which is simple and inexpensive.
1. Generally, for normal-pressure measurements, the liquid level at the bottom of the tower is what is measured. The range of possible liquid levels is not very wide, usually around 500–1500 mm. Jianye uses large float level gauges; although they are relatively bulky, they are inexpensive and have a wide range of applications, with no special requirements regarding temperature, viscosity, or pressure； 2. The temperature set by the poster is a bit high; using Rosement’s double-flange type sensor may result in readings at the upper limit of its range (if I’m not mistaken, the maximum temperature for this type of sensor is around 305 degrees). However, there should be no problem, as the nozzles and primary valves also help to dissipate heat. Yet, it’s impossible to quantify the amount of heat dissipated. For safety reasons, it’s recommended to use a float-type sensor (of course, provided its measurement range is sufficient) ； 3. Other level gauges that can consider a bypass pipe side-mounted design, such as float type and magnetostrictive type, can all meet the owner’s requirements ； The downside is that the bypass pipe takes up a lot of space and can easily block the walkways on the tower platform ；
A plate level gauge with double flanges can be used
Since the liquid level at the bottom of the tower is important for process operation, two sets of level gauges are generally installed: a double-flange transmitter + a float level transmitter.
As mentioned on the 4th floor, the medium at the bottom of the atmospheric pressure tower is residue, with a temperature that is roughly the same as that at the furnace outlet, i.e., ≥370°C; attention must be paid to high-temperature considerations when selecting measuring instruments. The measurement methods we use are float level gauges and differential pressure transmitters; the differential pressure transmitters are equipped with isolation tanks, and ethylene glycol is used as the flushing medium. It is sufficient to carry out flushing once a week during maintenance.
Our unit uses both a float level gauge and a double-flange level gauge to measure the liquid level at the bottom of the atmospheric pressure tower in its old units； The new unit uses two sets of double-flange level gauges for measurement.
Float level gauges and double flanges are used; a radiator is required for double flanges.
A differential pressure transmitter can solve your problem. For non-crystallizing media, you can directly use pressure piping to measure the pressure; for media prone to crystallization, a remote diaphragm differential pressure transmitter should be used. We use those manufactured by Chuan Yi Yokogawa. You might want to give it a try.
For the liquid level at the bottom of the atmospheric pressure tower, float level gauges and double-flange level gauges are used; a differential pressure gauge can also be employed, but backwashing is required
We use floating balls and differential pressure to measure liquid level; water is used as the isolation fluid, and heating as well as backwashing are provided (in the south). The results are satisfactory.