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Modern level measurement for centuries old site

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Dry Bulk,

Since the days of Sir Isaac Newton and Benjamin Franklin, people have been digging clay at Sibelco’s site in North Devon, UK.

From hand-cut clay transported by horse and wagon to today’s automated extraction techniques, Sibelco’s production has increased over these centuries to 200 000 tpy Along the way, Siemens process instrumentation has helped this modern company keep production moving from the clay quarry to finished product load out.

Front-end loaders fill lorries with 30 tpd from the 25 m opencast quarry. Lorries travel out of the quarry and dump massive pieces of clay onto the unloading conveyor.

As materials slowly move up the conveyor towards the shredder, a Siemens SITRANS LUT400 ultrasonic controller and an Echomax XPS-15 transducer monitor levels above the shredder feed.

The level measurement system is connected to the control of conveyor speed driven by hydraulic motor – when level or feed increases into the shredder, the conveyor speed slows down. And vice versa – when level or feed decreases in the shredder, the conveyor speed increases to maintain an efficient, uninterrupted shredding process.

Accurate and reliable measurement is crucial in this spot early in the production process. Although the heavy-duty steel shredder has tungsten-tipped teeth and spins at 70 RPM, operators do not want the shredder to become overloaded with clay.

SITRANS LUT400 keeps reliable measurements of materials in the shredder. Operators installed and programmed the controller using the device’s Quick Start Wizard, without requiring help from a technician or factory support.

Meanwhile, the Echomax transducer mounted above the shredder is fit for this type of rugged application, even with stones and large pieces of clay moving below it.

Sibelco also uses a SITRANS UL S200 ultrasonic level switch as a high-level alarm in case a large rock or some other obstruction blocks the hopper. The SITRANS ULS200 ultrasonic level switch acts a backup safety function to the process.

The shredder’s teeth take large pieces of clay down to what Kevin Bennett, Site Quality Controller, describes as “potato-sized” pieces, and then eventually down to 40 mm finished pieces of shredded clay. Once materials are sized correctly, they move to a transfer conveyor, which is controlled to run at the same speed as the shredder intake belt. A giant magnet positioned above the conveyor extracts any metal pieces from the newly sized clay as it moves upwards towards Sibelco’s storage bays.

Above the row of 12 bays moves a shuttle conveyor with a SITRANS LR560 radar level measurement transmitter mounted on it. The transmitter monitors material levels in each storage bay and, when the bay is full, the device sends a signal telling the shuttle conveyor operator to move to the next storage bay and begin filling.

The Echomax transducer relays continuous level readings to the controller, while the SITRANS ULS200 provides a high level alarm if clay reaches a certain point above the shredder.

SITRANS LUT400 ultrasonic controller reliably monitors levels of clay moving from the intake belt conveyor to the shredder. These storage bay levels are also displayed outside the processing building for lorry drivers to monitor. To keep Sibeclo’s high production efficiency, it is important for lorry drivers to know how much of each clay grade is in each storage bay.

The high-frequency 78 GHz SITRANS LR560 measures reliably even in this difficult environment. Its flush-mounted antenna can tolerate more material buildup than can a lower-frequency device, which is a benefit when dealing with clay. Important in this application are SITRANS LR560’s open air approvals, suitable for Sibelco’s open storage bays.

All those centuries ago, this type of clay earned the name “ball clay,” as workers cut cubes of it from the ground by hand and stacked them on a horse-drawn wagon. When customers received the clay, often its sharp corners were rounded during transportation, and what had been cubes then resembled balls.

Now an automated facility, Sibeclo focuses on health and safety for its workers and improving production efficiencies. As Richard Davey, Project Engineer at Sibelco, said: “Siemens level measurement equipment benefits us every day. Easy to install and maintain, we depend on it.” From the past to present, Sibelco’s clay continues to be produced to the highest standards, desired by customers worldwide.

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