Company takes charge of new bag filter system installation work at Hanson Cement’s Ketton Works
HANSON Cement have recently replaced two electrostatic filters with new bag filters at their Ketton Works to improve the recovery of dust particles, as well as reducing particulate emissions.
All cement plants in the UK a required to comply with safe emission limits to air, land and water with reference to best available technology. Various technologies are available to undertake this task, including electrostatic precipitators (ESPs) and fabric filters.
Both of these technologies are generally capable of meeting emissions limits for dust if correctly implemented and maintained. ESP filters, which use charged plates to attract dust particles, are suitable for handling gas streams in excess of 260°C, but fabric filters have become the leading technology on cement plants due to improvements in filter cloths.
Hanson Cement approached Fairport Engineering in early 2016 to discuss a plan for the replacement of their ESPs with bag filters on mills 9 and 10 at Ketton Works.
Having identified their preferred bag filter manufacturers, Hanson wanted an organization to act as main contractor to assume overall responsibility for the project, including taking control of the site under the CDM 2015 regulations and managing the design, supply and installation of the balance of plant.
After reviewing the construction phase options with Hanson, Fairport developed a proposal that would minimize disruption to cement production but meant work would have to be undertaken within two pre-planned three-week shutdown periods, one for each filter.
Mill 9 was the first unit to be replaced, and once pre-works and site establishment had been completed, Fairport took control of the site under the CDM 2015 regulations. Installation teams worked in back-to-back shifts on a 24-hours-a-day, seven-days-a-week basis to disconnect and remove the existing ESP.
Support structures and the existing fan and ducting were also removed to prepare the location for the installation of the new bag filter. The new system also required the installation of new screw conveyors and rotary airlocks, the reconfiguration of existing control panels, and the installation of new 160kW central exhaust fans and associated clean gas ducting.
All works were completed within the agreed shutdown period, following which was a short break prior to Mill 10 shutdown. Installation of the second bag filter, together with its attendant equipment and processes, was again successfully completed and handed over within the agreed period.
The construction phases of this project could only begin after detailed planning and the preparation and agreement of risk assessments and method statements (RAMS) to ensure all equipment could be safely removed and replaced. Working at height and the use of cranes with fly jibs (see photograph) added an extra level of complexity.
However, maintaining a safe working environment on an operational site is a specialist skill that Fairport have developed over many years, and as a result they were able to deliver the construction phase on time and to budget, with all works completed safely with no lost-time incidents, despite the expenditure of more than 15,000 construction hours.
Moreover, it has been reported that, to date, the daily averages on both filters are well below Hanson Cement’s target emission level.