Application of Ultrasonic Level Transmitter for Level Measurement of Limestone Slurry

A large state-owned chemical company in north of China purchased a batch of Jiwei Uson-11 Ultrasonic Level Transmitter to measure and monitor the level of wastewater and limestone slurry in May last year. The feedback from the customer was that the Uson-11 for wastewater has been working accurately and reliably as specified since the installation, but two Uson-11s for measuring the level of limestone slurry were not working well and showing inaccurate level measurement. Sometimes measurement data varied and false liquid level alarm happened.

Jiwei sent its experienced engineer immediately to investigate the situation onsite and provide technical support when the customer´s feedback was received. The engineer found the problem was repeatedly happening onsite. After investigating and analyzing the problem, he recognized that it was not due to the product quality but because of onsite application conditions.

Through onsite investigation and analysis, the engineer from Jiwei found failure of the instrument in measuring correct level of limestone slurry had three main causes:

The application was with a stirrer in the vessel and the liquid surface was quite dynamic. Because the liquid level was dynamically waving with uncertainty, the signal received by the transducer was disturbed and the measurement accuracy of the instrument was affected.

The beam angle of the installed Uson-11 is 8～12º. If the instrument is installed too close to the wall of the vessel, there will be more false echo signals received by the transducer because of beam transmitting angle and multiple reflections. The measuring accuracy will be reduced as a result.

3、The Uson-11 with problems was installed without a shelter.

C＝（331.45＋0.61t/）, t is in ℃ and C is in m/s

In north of China, usually it is hot and dry during the summer and extremely cold in winter. The ultrasonic level transmitter installed outdoor is susceptible to the changing temperature. It will introduce error in ultrasonic sound travel speed and results inaccurate level measurement. In this situation, install an extra sheltering box for the Uson-11 will avoid big changes of the temperature. At the same time, it would be better and necessary to install a temperature sensor where reflects process temperature and use its reading to calculate the correct sound wave travel speed.

Three、Solutions to solve the problem in this application:

In order to solve the problems of inaccurate and unstable level measurement in this application for limestone slurry based on analysis above, a few detailed suggestions were proposed:

Because the Uson-11 customer selected was with 10m measuring range and 10ºbeam emitting angle, put all of these into consideration, we recommended the customer to install the Uson-11 60cm apart from the wall of the vessel.

Fig.2

After all the recommendations above were followed and appropriate measures were taken, the problems in this application were successfully solved. Two Uson-11s from Jiwei have been working well since they have been reinstalled and the previous problems have never happened again.

Four、Technical features of Uson-11 from Jiwei

Comparison with common ultrasonic level transmitter, Jiwei Uson-11 has following advantages thanks to its innovative design and modifications:

1、With updated software and hardware. Dramatically waving Medium surface is very common in industrial applications. Jiwei updated the software and hardware for Uson-11 to improve its robust and stability. A time extended averaging algorithm is added into the program and improves the adaptability of the instrument for complicated working conditions. In hardware, effective and rigorous electronic filter circuit is added to filter out the secondary wave signal or clutter signal.

2、With temperature compensation function, adaptable to the working process with greater temperature difference, strong adaptability and high measuring accuracy.

3、Ingress protection level of Uson-11 reaches to IP66/IP67.

4、With RS-485 interface.

Uson-11 Ultrasonic Level Transmitter Jiwei developed is a highly reliable and accurate instrument. It is widely used in various industrial process, smart city management and wastewater treatment. It is highly evaluated by our customers.