Emissions, Sound Levels, Fuel Usage All Reduced
Four years ago, Fiegl GmbH of Bavaria invested in the retrofit of an asphalt-mixing plant tower, as well as the replacement of the baghouse. The retrofit led to immediate reductions in emissions, sound levels and fuel usage.

The time frame for the retrofit was extremely tight because it was important to avoid lengthy downtime and production outages in mid-season. This meant that the changeover had to be completed during the long Corpus Christi weekend in May.

Work on dismantling the old baghouse system – which had been in operation for 20 years – began on the day of the public holiday and the trial run for the new system started on the following Monday morning. Result: successful!

Thanks to the new baghouse, Fiegl now has a modern production plant that also ensures environmental-friendly operation at its facility in Pleinfeld, Bavaria. This project yielded benefits across the board, with significant reductions in emission values, sound levels and energy requirements.

Fiegl has had its own facilities for producing asphalt for an extensive period – mainly to supply its own paving crews, but also to meet the needs of public-sector and private customers. Managed by the third generation of the founding family, the company was established on the shore of the Greater Brombach Lake in Middle Franconia 117 years ago. It offers a complete range of services focusing on road construction and civil engineering. It also has appropriate construction machines for these purposes. Two paving crews operate within a 50-kilometre radius of the company's site.

The First Major Step

The asphalt-mixing plant dating from the 1970s was replaced in 2014. The tower of the Universal 240 plant from Ammann has an impressive height of 35 metres. This plant enables Fiegl to produce as much as 1,500 tonnes of asphalt each day. The asphalt storage silo has a capacity of 240 tonnes and the hot aggregate silo holds 120 tonnes. Granular asphalt can be added as cold material via the elevator. Two buffer containers are also available for different grain sizes.

At the same time, the bitumen tanks were also brought into line with the latest technological standards. Two of them were replaced and one was converted. Nowadays, all of them are heated with electricity instead of thermal oil. The filler silo was also replaced. The two companies had already collaborated smoothly on this extensive programme of activities and the aim was to repeat this success with the new project.

Drawing on Positive Experiences

Excellent coordination was the key factor that ensured good progress. First and foremost, there was an "Installation Kick-Off" session one week before work began. Everyone involved in the project gathered together on-site to discuss all possible eventualities: project managers, engineers, electricians, fitters, the customer's staff in charge of the project, and of course the mixing engineers and representatives of the crane company.

Successful commissioning of the baghouse system at the end of a labour-intensive long weekend once again confirmed that this is the right approach.

The Next Step

As well as reducing emission values, sound levels and energy requirements, the new baghouse system offers key benefits thanks to its underpressure reserves and process reliability.

The Ammatex filter bags have long service lifetimes. They are highly resistant to extreme temperatures and are impregnated with PTFE as standard. The seams are also made of PTFE. Polytetrafluoroethylene is the chemical name for the plastic that is often called "Teflon" in common parlance, but "Gore-Tex" is the usual term when referring to fabrics.

The filter bags eliminate the need to use fresh air flaps, so no additional air is required to clean the cloths. Thermosetting guarantees the dimensional stability of the filter bags. The type AFA 3089 baghouse plant in Pleinfeld can operate at a rate of 63,000 Nm/h and is controlled via a frequency converter.

The filter surface area is 1,045 m² – more than adequate to meet the environmental requirements for the operation of the asphalt mixing plant.

A RETROFIT TO PROTECT THE ENVIRONMENT

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