Scrubber technology designed, manufactured and installed by ACWA AIR, has helped Tata Steel achieve a 40 per cent reduction in atmospheric emissions from a limestone kiln in Cumbria. Tata Steel operates four Maerz kilns, producing high grade lime for the iron and steel industries

To control kiln emissions to specific levels set by the UK Environment Agency, each of Tata Steel’s the four kilns is installed with a wet scrubber at the top of the plant, 100 feet above ground level and often considered a landmark for motorists travelling through Cumbria along the M6 motorway.

The four scrubbers have had their shells refurbished several times over their lifetimes, due to the abrasive nature of their operating environment – always ensuring they achieve the required abatement levels.

Recently, however, the scrubber on the No 4 kiln was in need of refurbishment and in line with Tata Steel’s pledge to minimise emissions on all their production processes, the company asked ACWA AIR what could be done within the constraints of the existing system to reduce emissions. Following a site survey, ACWA AIR recommended that, concurrent with the shell refurbishment, the existing process should be modified to integrate its well proven venturi slot tray technology within the process. This would be more effective than the existing scrubbing technology and achieve much higher collection efficiencies.

Working within the constraints of the existing scrubber shell, ACWA AIR was able to engineer a venturi slot tray which provided lower emissions of dust, whilst making use of the existing scrubber vessel. The system integrated with the existing water and effluent pipe-work and gas seals and did not impose any significant changes to the operation of the lime kilns.

The new scrubber shell was manufactured on Teesside by CB Construction, and the four-slot plate section fabricated by ACWA AIR in Huddersfield. The outage was planned to fit within an eight-hour period including the total dismantling and removal of the existing No 4 new scrubber shell from the kiln platform, the lifting in place of the new modified scrubber and restarting production.

Following commissioning of the modified scrubber, independent tests have proved emissions from the No 4 lime kiln are consistently 40 per cent less than values recorded before the refurbishments. Tata Steel also reported no adverse effects to the production process or kiln controls.