SCR Catalysts and DeNOx Systems

H+H Engineering & Service supplies selective catalytic reduction (SCR) systems that reduce NOx emissions from combustion engines. A reducing agent injected into the exhaust gas evaporates and releases ammonia (NH3), which converts NOx on the catalyst surface into nitrogen (N2) and water. Systems are tailor-made for each application.

Catalysts

• SCR catalysts – mostly homogeneously extruded honeycomb catalysts made entirely of catalytically active titanium oxide, tungsten oxide and vanadium pentoxide, reinforced with glass fibres; delivered pre-installed in element frames or modules
• Coated metal catalysts integrated directly into the exhaust duct for some applications
• Oxidation catalysts (DOC) – coated metal foils with precious metal coating (platinum, palladium), in a separate round casing or combined with the SCR elements

Technical data

• Operating temperature: 180–540 °C overall; 260–320 °C minimum to 540 °C maximum for combustion engines (gas/diesel/heavy oil)
• Typical space velocity approx. 10000 h-1; geometry and vanadium content adapted to each application
• Formaldehyde reduction up to 20–30% by the SCR catalyst; almost complete with an additional DOC
• No loss in fuel economy when correctly sized for acceptable backpressure
• Automatic start of urea injection once the catalyst reaches operating temperature

System components

• Reducing agent pump or pump station and dosing unit
• Mixing unit with injection lance
• Catalyst housing (reactor) with SCR catalysts
• Control unit
• Options: compressor, reducing agent tank, NOx analyser/sensor, ethene gas chromatograph, sootblower

Compliance

IMO MARPOL Annex VI Regulation 13 (maritime), EU 2016/1628 and CCNR 2 (inland waterway vessels), plus stationary-sector regulations.