21 containerised after-treatment systems for a Swiss datacenter

The challenge

A new datacenter in Switzerland is backed by a fleet of diesel gensets sized to carry the full IT load through a grid outage. Switzerland enforces some of the strictest air-quality limits in Europe through the Federal Clean Air Ordinance (LRV, Luftreinhalte-Verordnung), and the site’s permit demanded deep reductions in both particulate matter and nitrogen oxides from every engine, even though each genset runs only intermittently, for testing and emergencies.

The operator needed each genset brought into full LRV compliance for both soot and NOx, fitted with continuous emissions monitoring to prove it, and held to a tight noise limit at the site boundary. The footprint on site was constrained, the twenty-one systems had to be effectively identical, and they had to arrive ready to set down and connect rather than be built up in the field.

Our approach & engineering

Axces packaged the entire exhaust after-treatment train into a single containerised, all-in-one system, then standardised it across all twenty-one gensets. Putting the diesel oxidation catalyst, particulate filter, SCR reactor, silencer, chimney and monitoring into one container means the whole compliance chain is engineered, factory-tested and certified as a unit, and installed in a single lift.

Two-stage emissions reduction

A diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) take out the carbon monoxide, hydrocarbons and soot, achieving up to 99% reduction in particulate. Downstream, a selective catalytic reduction (SCR) stage doses reagent through an injection grid and mixer to convert nitrogen oxides across the catalyst, achieving up to 95% NOx reduction. The catalyst and filter were sized to hold conversion at the low exhaust temperatures typical of a lightly-loaded backup engine, where the chemistry is hardest to sustain.

Integrated silencing, stack and monitoring

An exhaust silencer is built into the same container, holding the genset to 75 dB(A) at one metre, and the flue discharges through an integrated chimney. A continuous emissions monitoring system (CEMS) is fitted to each unit so the operator has live, recorded proof of compliance against the permit.

One containerised design, repeated across all 21 gensets
Full after-treatment train (DOC, DPF, SCR) plus silencer, chimney and CEMS in one container
Sized for the low exhaust temperatures of an intermittently-run backup engine
Factory-built and tested as a unit, installed in a single lift
Live emissions data per unit via the integrated CEMS

Scope of supply

Axces delivered the complete emission- and noise-control scope as a repeatable containerised package, fabricated in-house:

21 × all-in-one after-treatment containers (DOC + DPF + SCR)
21 × integrated exhaust silencers sized to the site’s dB(A) limit
21 × integrated chimneys
21 × continuous emissions monitoring systems (CEMS)
Reagent dosing skids, injection grids and mixers, pre-fitted in each container
Control interface and emissions data output to each genset and the site

Results

All twenty-one systems were built to one design and delivered as matching containers, bringing every genset into LRV compliance for both particulate and NOx with monitoring built in to prove it.

Up to 99% soot reduction and up to 95% NOx reduction, meeting Swiss LRV limits
Exhaust noise held to 75 dB(A) at one metre with the integrated silencers
Continuous emissions monitoring on every unit for recorded proof of compliance
21 identical containers: one set of spares, one maintenance procedure, one lift to install