Project TCL – Quarry kiln system

As installations go, this is a big one! 

We were advised by one of our regular suppliers of a requirement by Tarmac, the UK's leading sustainable building products, for a cement kiln filter system in Wales.  Part of a successful tendering process was the requirement to be a member of Achilles.  

Achilles is a worldwide community of more than 800 accredited buyers and 175,000 suppliers.

We are proud to say we were successful on both accounts, and now add our membership to our ISO 9001 accreditation.

Shortly before winning the contract for a filter system, fan and ducting to the kiln hood and cooling tube elbows, a design change requirement was advised. This resulted in a change to the location of the filter and the resultant re-designing of the ducting arrangement whilst the contract was in progress.  

In order to make these design changes, a 3D scan of the area was commissioned which allowed our designer to produce a 3D CAD model of the kiln, local building, and surrounding steelwork where the filter and fan would need to be located. 

Working in partnership with the client we were able to arrive at a solution that placed the filter legs on a steel structure and devise a new ducting layout that avoided ground-mounted duct supports while still utilising steeply inclined ducting which has proved effective in other clinker kiln applications.  

With the final design having a total of around 100m of 925mmm diameter ducting, rising to a height of 30m plus above ground level and 3 separate areas of extraction including a large extraction hood weighing 400kg alone for the project to be a success we knew an experienced and skilled team of erectors would be crucial.  The team would need to execute the installation of the filter and ducting largely during a short but well planned shut-down period.  Mii engineering is such a company and besides fabricating the new kiln hood to which our ducting connects, they would have a skilled team of erectors on site for our client to install that hood.  Based locally and with an impressive resume of work plus all necessary credentials with regard to compliance we were in no doubt, Mii were our best option for such a large and crucial installation task.

The design of the filter was quickly agreed upon and the fabrications underway.  The opportunity to erect the filter and post-filter ducting was available outside of the planned shutdown so the filter was trial assembled in the fabrication shop.  The hopper and full galvanised support structure was delivered to the site already assembled minimizing the required on-site assembly work. The 2 filter sections were then delivered to the site and the full basic assembly was then ready to be craned into position just 2 days after the first delivery to site.   

In positioning the filter, the critical elements were the location of the support frame feet on the highest load-bearing areas of the structural steelwork and positioning the hopper screw conveyor outlet over an existing floor mounted chute.  With the filter successfully craned into position the Outlet ducting to fan and from the fan to the chimney were also erected ahead of the shutdown.

Test points were included in the ducting from the filter to the fan and a glass rope packed expansion joint positioned before and after the fan.  At the top of the stack, provision was made for catenary wires for added security. 

All outlet ducting was silicone sealed between flanges where the inlet ducting is gasketed between flanges to prevent water ingress.

An access ladder with an intermediate platform was provided.

It was at this point, with the filter and following ducting all erected successfully in just 2 weeks, that things took a turn for the worst weather-wise at least! 

The meticulously planned shutdown, unfortunately, coincided with a series of what became almost weekly storms.  South Wales was hit repeatedly with high winds and flooding, being particularly close to the coast the site was hit hard by storm Ciara, Dennis, and Jorge in a period of weather that was unprecedented.  Of course, the ferocity and frequency of this weather meant using a crane and 28m working height cherry picker to erect a series of large cantilever brackets to a building, huge runs of nearly 1 metre diameter ducting high off the ground was inevitably taking longer than expected.  The duct supports measured up to 10m in themselves and 1 needed lifting onto the roof of an old control room, another large support required stub supports welding directly to the kiln tunnel.  The team on site continued to battle the elements and completed the main ducting run which climbs up to a height of around 30m above ground and drops back down to split to either side of the kiln hood.   A large fully modulating pneumatic damper is incorporated into the ducting at each extraction point which when used in conjunction with the inverter on the main fan gives full control over the system.   Unfortunately despite the best efforts of all involved, we were unable to overcome the setbacks of the storms and get the job to completion before the plant was put back into operation and the filter system commissioned.  By shutting the damper that will serve the standalone hood over the elbows the system has already proved itself successful in manage the dust emissions usually created on startup.