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13-year-old flow metering problem solved

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ACCURATELY measuring the flow of scrubber effluent used in single superphosphate (SSP) manufacturing has been a challenge at Incitec Pivot’s Cockle Creek plant for a long time.

Electrical/instrument technician Darren Saxby, who has worked at Cockle Creek for over 13 years, recalls that the scrubber effluent flow meters have been a major cause of frustration since he can remember.

“Over the years, we’ve tried different types of flow meters from various manufacturers, all with some degree of success, but none proved reliable over a respectable period of time,” said Saxby.

Incitec Pivot is a world class manufacturer and supplier of agricultural nutrients, and the Cockle Creek plant manufactures 250,000 tons of superphosphate for distribution to farmers throughout NSW.

Scrubber effluent is a key element in manufacturing, and with environmental benefits. Reusing the effluent allows the Cockle Creek plant to reduce the amount of fresh water used and eliminates the need to discharge it off-site.

The accurate measurement of the effluent flow is critical.

The harsh physical and aggressive chemical properties of the scrubber effluent provide many challenges for the plant operators, due to the ongoing presence of silica dioxide and hydrofluorosilicic acid.

Over the years, many modifications were made to the application to get more reliable flow measurements.

Some of these changes have been: different earthing arrangements to prevent earth faults through silica scale build-up; the introduction of low friction, high temperature plastic to limit scale build-up in pipes; changes to maintenance routines; and the introduction of on-line calibration checks.

Despite numerous trials of different brands of electromagnetic flow meters and ultrasonic (time-of-flight) flow meters, the problem of erratic readings remained.

In 2004, Saxby attended a trade exhibition and visited the Endress+Hauser stand to discuss his flow measurement problem. As a result, E+H sales engineer, Partha Gupta, visited the Cockle Creek plant and obtained samples to analyse and test. He recommended a Promag 53 electromagnetic flow meter with PTFE liner, tantalum electrodes and advanced evolution software.

As the flow meters in service at that time were proving unreliable, Incitec Pivot purchased and installed a Promag 53.

After a month of positive results, the company purchased and installed another Promag 53 in the second scrubber effluent pipework. Nine months later, both flow meters are providing reliable and accurate measurements.

“The use of the Promag 53 has cut maintenance by one-third, resulting in less downtime, and has made the task of producing quality SSP much more efficient,’’ said Saxby.

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