At present, the demand for crude oil reserves is increasing, the quantity of crude oil is constantly increasing, and higher requirements are also put forward for the performance of oil storage tanks.

When measuring the liquid level, the final measurement result needs to have extremely high accuracy, and there are many drawbacks in the previous manual measurement form.

1 Measuring principle and classification of radar level gauge

The actual working principle of the magnetrol radar level gauges is as follows. The radar level gauge uses the internal antenna to transmit electromagnetic waves, and the measured object will reflect the electromagnetic waves on the surface, and then the internal antenna will reflect the electromagnetic waves.

The magnetic wave is received, and the time from electromagnetic wave transmission to reception of the radar level gauge is proportional to the distance from the antenna to the liquid level, and then the liquid level height is calculated, and the working principle can be simplified as transmission→reflection→reception. Radar level gauges can be divided into two types according to the different working forms of electromagnetic waves: frequency-modulated continuous wave level gauges and pulsed microwave level gauges.

1.1 FM continuous wave level gauge

FM continuous wave liquid level gauge, the working process is that the antenna transmits the signal, and then the measured plane is folded back, and the antenna immediately accepts the echo, and the transmitted signal is the micro-wave signal at this time.

The wave is a chirped continuous wave. The echo received by the antenna, its microwave has been frequency modulated and changed. The frequency difference signal is rapidly converted into a spectral difference, and the measurement distance is calculated.

1.2 Pulse microwave mode level gauge

The time travel measurement system selected by the pulsed microwave type liquid level meter is "overview type". This system uses an antenna to transmit microwave pulses of a fixed frequency, and the material surface reflects it.

After that, the measurement system receives it immediately. The reflected microwave pulse is received by the antenna and then transmitted to the electronic circuit. After the signal is processed by the microprocessor, the microwave pulse and the echo reflected by the material surface are identified to calculate the liquid level.

2 Radar level gauge measurement features

The radar level gauge has the following measurement characteristics: ① The measurement results are highly accurate. Since the radar level gauge is not easily disturbed by external factors during actual measurement, the data measurement results are highly accurate and highly reliable; ② The measurement method is more reasonable. Since the radar level gauge is non-contact, compared with the previous manual contact measurement method, the components and equipment of the radar level gauge are more stable, so the measurement results are more reliable.

3 Application of radar level gauge in oil storage tank

3.1 Install the radar level gauge

The following conditions must be met when installing the radar level gauge: ①The radar level gauge cannot be placed in the middle of the oil storage tank to prevent the signal from being disturbed; ②The radar level gauge cannot be placed in the right direction of the liquid inlet. The upper position; ③ For some circular oil storage tanks with small diameter, the minimum distance between the placement position of the radar level gauge and the badger wall of the oil storage tank should be ≥35 cm. Generally, the distance between the tank wall of the oil storage tank and the radar level gauge is set to The diameter of the oil storage tank is 1/6-1/4.

3.2 Factors affecting radar level gauge measurement

The oil storage tank is an extremely important part of the radar level gauge measurement system. During the actual measurement process of the radar level gauge, the measurement results will be affected by some substances inside the body, resulting in a decrease in the accuracy of the measurement result box. Such factors include: the condensation of steam or oil and gas in the tank causes disturbance to the reflection stage, and the impedance jump at the connection position of the antenna. Impedance jumps occur inside the short tube, obstacles interfere with the reflection stage, and adhesions are overlaid on the high-frequency head, etc. When installing the still-pipe, special attention should be paid to whether the surface and interior of the still-pipe are flat. The time travel of the electromagnetic wave in the still-pipe will be affected by the slight change in the inner diameter of the still-pipe.

3.3 Common problems during measurement

Due to the many advantages of the radar level gauge itself, the radar level gauge can be widely used in oil storage tanks, but there are still some problems in the actual measurement process. The wave, that is, the echo is too weak. The main reason for this problem is that the oil level and the antenna direction of the radar level gauge are not kept vertical, and the magnetic liquid level gauge is disturbed or there are disturbance factors. Therefore, it is necessary to check the antenna of the radar level gauge to see if there are other adhesions or condensation. Clean the antenna and adjust the direction to the correct state.