The job mainly consisted in replacing the two existing filter heads (make Contimpianti – model 35M7), which worked with a cleaning system by mechanical shaking and had been in operation since 1985, as they could not meet any more both plant needs and the cost-performance ratio requirements. Contimpianti scope of supply included the partial dismantling of the existing filters and the assembly of the new heads, along with the necessary adaptation of the pipes connecting the filters to the fans, without stopping the crusher operation.
SCOPE OF SUPPLY
The conversion of the two heads went through the installation of a bags cle- aning system by compressed air jet air, which is regulated by controlling the pressure drop ΔP of the bags. The job on the existing filters involved emptying of the filter body and disman- tling of the internal partition panels that are typical for filters with mechanical sha- king technology and with backwashing of single sections; the main structure as well as the existing screw conveyor and rotary valves were maintained. The plant engineering, referred the to modification of connection pipe between filter-fan,
was aimed at recovering the intercep- tion valves of the filters, which had been already installed originally in view of al- lowing to execute any maintenance operation on each single filter without stopping the whole plant and, therefore, meeting the Client’s production targets. The check of capacities and vacuum conditions at the crusher discharge, which were executed during the sur- veys necessary for the engineering, brought to the need of increasing the fan rotation speed by 10%, in order to obtain a good dedusting of the crusher and restore the environmental health requirements compliant with presen- ce of operators working near the plant.
ASSEMBLY
In view of optimizing and speeding assembly activities as much as possible, after a careful inspection performed with the site manager, Contimpianti decided - instead of using the existing overhead travelling crane serving the crusher, as poorly functional to the job need to remove part of the building front wall, leaving the crane a free access to the working area. Thanks to this option Contimpianti managed to dismantle part of the filters easily and install the new filter heads, which had been preassembled at its workshop. Modification and connection of the new pipes, which were performed during a weekend, did not interfere at all with the cement plant production programs. Additionally, thanks to an accurate assessment of the risks and the excellent cooperation with the Safety Coordinator during the execution of the job, the works
were completed in time, according to the expected working schedule and in total safety conditions for all working team.
COMMISSIONING
After only two weeks from opening of the site, the first filter was started on July 14th 2014, while the second was finished and started on July 17th 2014. The conversion of the filter heads, along with the modification of pipes between filters and fan and the adjustment of the fan speed rotation, has finally made possible to obtain a very efficient dedusting of the crushing plant, to reach the performance figures such as stipulated in the contract and restore the environmental health requirements compliant with presence of operators working near the plant. After completion of the building clad- ding, conclusion of all site activities and clearing-up of the working area, on July 21st Holcim lastly took over the new plant with great satisfaction for all parties involved in the project.
