Video monitoring and cleaning solution pays dividends for tioxide plant

Paul Boughton

An ingenious remote video monitoring and cleaning system developed by Ionix’s Telespection Services team, is saving significant time and money at Huntsman Tioxide’s plant in Grimsby.

At the plant, the titanium dioxide liquor is refined using three Broadbent solid bowl decanter centrifuge rotating units. In theory Huntsman should have two rotating units continually in operation with the third acting as a spare. Unfortunately, in practice, this rarely happens as material build-up in and around the four water spray nozzles steadily reduces the efficiency of the centrifuges and eventually completely blocks them.

In the past, Ian Shaw, Huntsman’s assistant engineer, has been somewhat frustrated over this situation: “Unfortunately normal access to the nozzles can only be achieved by removing the unit from operation, completely stripping down the unit and sending it back to the manufacturer. The machining tolerances on the centrifuge components are very tight and often additional engineering work is needed during reassembly. The strip down and rebuild can cost upwards of £8000.”

To try to minimise the frequency of strip downs, Huntsman approached Ionix Group’s Telespection Services to see if they could come up with a more cost effective solution involving cleaning the nozzles in-situ.

Using a video probe, Ionix Group conducted a investigation and realised a bespoke solution was needed to gain remote access to the nozzles by travelling 1500 mm along a 100 mm diameter tube and then dropping vertically down a distance of about 300 mm to the nozzle chamber.

The solution was based around a length of motorbike drive chain and a heavy-duty boden cable. The assembly consists of a 1500mm metal channel used to guide the 300mm length of drive chain, which is attached to an aluminium bar. The cleaning tool, comprising the cleaning tip, operating cable and two concentric plastic tubes is fixed to the free end of the drive chain. Using detailed drawings of the centrifuge, the team were able to carry out a mock bench top cleaning exercise to demonstrate the principle of operation to Huntsman’s engineers. Satisfied with the results of the test run, Huntsman allowed Telespection to carry out a live cleaning trial on site.

With the channel in-situ in the tube the bar is fed along the channel until the chain drops into the nozzle chamber. The centrifuge can be moved by hand to position the first nozzle ready for cleaning. Once the cleaning system is in the nozzle chamber, accurate positioning, guided by the video probe, can be achieved by moving the cable and chain relative to each other. The weight of the chain ensures the cleaning system sits over the nozzle and does not move during cleaning.

Once the cleaning system is in position the tee bar on the end of the drive cable can be rotated to clean the nozzle. There are a variety of interchangeable cleaning ends, including a chisel tip, pointed tip, screw tip and wire brush tip. Once the nozzle is cleared of deposit an air line can be used to blow out any loose debris. A vacuum hose can also be positioned over the nozzle or in adjacent areas to clear out any loose debris which might block the nozzle on start up. Once a nozzle is considered clean, the unit can be rotated to position the next nozzle below the cleaning system. This is recorded on tape and retained for records.

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