Project BHC – Cement Mill 2 Ducting

CONSULTANT’S REPORT

The previous owners of the plant consulted us back in 2012 to look at replacing the ducting for a cement mill which subsequently didn’t go ahead.

After the plant was taken over this project was re-visited but rather than use the existing drawings, the customer wanted a neater design which was easier to maintain and access.

Our client’s existing filter was to be re-used and they undertook the work to replace all the bags. They installed a new fan which we helped specify the pressure drop (550mmwg) and volume to allow an extraction volume of 1,250m3/hr over the 8 extraction points.

The previous ducting was underperforming. In some sections of the ducting the velocity was 11-12m/s and no way of balancing the system so some areas were getting more extraction than others and the ducting was getting blocked.

Filter designs worked alongside the operatives to ensure the new design was operator friendly.

The ducting was split over three levels and in some areas the space was very tight. To enable us to work around this we modelled quite a lot of the area to ensure that the newly designed ductwork would fit.

Once the site layout had been modelled, we then calculated the duct sizes to ensure 17 – 20m/s in the ducting to convey the cement dust to the filter.

As cement dust can be abrasive, we opted to have a removable hardox plate wear bends. 

We also installed access hatches in the straight runs of ducting to allow maintenance inspections.

The installation had to be carefully planned as site only had a shutdown for 10 days and the existing ducting had to be removed prior to the new ducting. This also meant that our installation team had to work over the weekend

Scaffolding was installed by our client ahead of the shutdown date as some of the areas where the ducting was to be installed was a high level.

Our client had a removal team who worked night shifts so that during the day our installation team could follow on installing the new ducting.

The ducting was manufactured from 3mm galvanised sheet with 6mm flanges and fully gasketed throughout.

The filter inlet ducting was design to ensure an even flow across the three sections. As the installation was across three levels and multiple extraction points, we installed slip joints to allow flexibility on site.

Each extraction point was fitted with a manual blast gate damper to allow us to fully balance the system once it had been installed.

The filter outlet ducting was quite tricky to install due to the head room above the filter.

Our client brought a crane in to lift the heavier duct pieces into position. The ducting was then supported using clamp supports and threaded bar to give some movement within the ducting.

Once the install was completed, we went back to fully balance / commission extraction system. 

Client Testimonial

We contacted Filter Designs Ltd to design, supply and install replacement ducting on our Cement Mill Auxiliary Dust Control Plant. The original system was unbalanced and prone to both blockages and excessive wear due to inconsistent duct velocities. The project was completed in a very tight schedule from the initial proposal stage, through design iterations and final installation due to production requirements.

The correctly designed ducting installed in conjunction with other improvements has seen a drastic improvement in the performance and reliability of the system. The success of this project has led us to repeat the exercise on an additional part of the plant.

Filter Designs Ltd provided an excellent service throughout all stages of the project – design, installation and commissioning – and worked closely with us to understand our specific requirements and deliver these on time and within budget.