SCRUBBER technology has helped Tata Steel achieve a 40% reduction in atmospheric emissions from a limestone kiln in Cumbria.
The company operates four Maerz kilns at Shapfell, producing high grade lime for the iron and steel industries. To control kiln emissions to specific levels set by the Environment Agency, each of the kilns is installed with a wet scrubber at the top of the plant, 100 feet above ground level. For many years, the installation has been a striking landmark alongside the M6 motorway.
Because of the abrasive nature of their operating environment, the scrubbers have had their shells refurbished several times. Recently, however, the scrubber on the No. 3 kiln was in need of refurbishment and in line with Tata’s pledge to minimise emissions on all its production processes, the company again asked ACWA AIR to reduce emission levels.
Following a detailed site survey, ACWA AIR recommended that, concurrent with the shell refurbishment, the process should be modified to integrate its venturi slot tray technology in the process. This would be more effective than the existing 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 that provided lower emissions of dust, while making use of the existing scrubber vessel. The system integrated with the existing water and effluent pipework and gas seals and did not impose any significant changes to the operation of the lime kiln.
The new scrubber shell was manufactured on Teesside by C B Construction, and the four-slot plate section fabricated by ACWA AIR in Huddersfield.
The outage was planned to fit within an eight-hour period. This included the total dismantling and removal of the existing No. 3 kiln scrubber shell from the kiln platform, lifting into place the new modified scrubber and restarting production on the kiln.
Following commissioning of the modified scrubber, independent tests have proved that emissions from the kiln are consistently 40% less than previous values recorded before the refurbishments. Tata Steel also reported no adverse effects to the production process or kiln controls.