Clamp-On Ultrasonic System Solves Slurry Flow Measurement Problem

By using an easily installable Siemens FUP1010 portable flow measuring check kit, shown here, a Chilean copper
mine was able to quickly determine that an external clamp-on flow meter would provide acceptable results while
eliminating the costly maintenance requirements experienced with a previous electromagnetic flow meter.
For a Chilean copper producer located in the Antofagasta region of northern Chile, finding a flow measurement system to replace their existing setup was a matter of thinking outside the box. Although several key performance requirements suited the electromagnetic flow meters the mining company had been using for years— including high accuracy and reliable performance— a pressing need for a low-maintenance, easily installed system disqualified that technology, and the company had to look elsewhere for alternative solutions.

In the mine’s existing setup, the flow of copper pulp slurry running through a 14- in. (DN 600) pipeline was measured by an electromagnetic flow meter that was maintenance- intensive due in large part to the rubber liner fitted to the flow meter. The liner was meant to reduce abrasion on the inside of the pipe but given the harsh nature of the copper slurry and the very high content of suspended solids (65%), the electromagnetic flow meter had to be replaced almost every year.

Because the electromagnetic flow meter was of the inline type, changing it was not an easy task. Operators had to shut down the entire process while the old flow meter was removed and replaced with a new one. Doing this was both time-consuming and expensive both in terms of the required manpower as well as lost production output.

In seeking an alternative measurement technology able to deliver the key performance requirements of low maintenance and easy installation the miner contacted Siemens, which recommended a flow meter based on clamp-on ultrasonic technology with sensors mounted on the outside of the pipe and an accuracy in the 1%–2% range. This solution, according to Siemens, offered several benefits for the customer.
• The flow meter could be installed without shutting down the process.
• The sensors would be mounted on the outside of the pipe, separated from the abrasive fluid contents, eliminating the wear problems that accompanied the electromagnetic flow meters. An annual liner or sensor replacement simply became unnecessary.

The FUP1010 check meter was installed, programmed
and able to measure slurry flow in less than 20 minutes.
Once the meter’s flow-measuring accuracy was
confirmed, the mine decided to install the Sitrans
FUS1010—the dedicated version of the flow meter.
Although the customer was advised that the clamp-on ultrasonic technology in this application would not offer the same level of accuracy as the electromagnetic flow meter, Siemens reported that they were still quite comfortable with the proposed solution— a level of precision within the 1%–2% range was considered more than adequate, especially when the non-intrusiveness, ease of installation and low maintenance requirements of the clamp-on ultrasonic solution were taken into account.

Before making a final decision on whether or not to purchase the system, a Siemens team brought in a portable check metering kit, the Sitrans FUP1010, to conduct an initial test. The check meter was installed on the pipe and programmed in less than 20 minutes to measure the flow, promptly demonstrating its easy installation, reliable performance and capability of measuring the very thick (65% solids content) copper slurry. Impressed with how quickly the sensors were installed as well as by overall performance, the company decided to install the dedicated version of the portable check metering kit, the Sitrans FUS1010, with permanently mounted sensors.

An additional key feature of the Sitrans FUS1010 is its ability to measure flow by two modes of operation: WideBeam transit time and Doppler. Transit time operation offers an accuracy of up to 0.5% of flow and is the preferred mode of operation for relatively homogeneous liquids. Doppler operation, on the other hand, is designed for slurries with extensive suspended solids, with 1%–2% accuracy. According to Siemens, having both modes of operation ensures suitability for virtually any mining or minerals processing industry application because the system can be set to automatically switch from one mode of operation to the other, eliminating any need to change meters.

Information for this article was provided by Sheldon Shepherd, marketing manager for industry business development within Siemens’ Sensors and Communications division.

As featured in Womp 2009 Vol 08 -