Tier 4 Final/Stage IV, the latest international standard for non-road diesel engines is now mandatory in the USA, Canada and the European Union. But what does it mean for the owners and operators of our equipment?
Quite simply, it implies a substantial improvement to our customers’ working environment. Tier 4 Final engines reduce PM (particulate matters) and NOx emissions (nitrogen oxides) by more than 90% compared to Tier 3 levels. This means the air at construction and mining worksites will be almost totally free of harmful fumes, and that also benefits nearby communities and society as a whole.
The first experience
When it comes to drill rigs, the immediate effect of the regulation is experienced at the fueling station. For the first time, operators are required to use two tanks – one for the diesel fuel and one for a special reagent. This reagent is an aqueous urea solution commonly known as AdBlue or DEF (Diesel Exhaust Fluid). It consists of 32.5% urea, i.e. high-purity carbamide – CO(NH2)2 – and 67.5% deionized water. It is non-toxic, safe to handle and harmless to the environment. Despite its name, AdBlue is also colorless. In order to accommodate this additive, we have re-designed our diesel-powered equipment by applying advanced exhaust gas aftertreatment engineering, similar to that required for road vehicles.
The aftertreatment configuration,which was changed between the Tier 3 and Tier 4 Interim stages, now includes a urea tank and DEF injection system installed between the diesel particulate filter (DPF) and the Selective Catalytic Reduction (SCR) unit(Fig 1). This is now the standard on all Atlas Copco equipment for Tier4/Stage IV countries, for example our FlexiROC and SmartROC drill rigs.
Easing the transition
To help our customers make the transition to Tier 4 Final engines and the benefits it brings, our design team has incorporated Fig 2. Examples of the symbols and gauges on the SmartROC display panel that make it easy for the operators to monitor the urea during operation. a number of helpful features into the new equipment, for example:
- easily identifiable blue colored caps onthe urea tanks
- new gauges in the control panels that enable the urea level and aftertreatment
to be monitored at all times as well as easy-to-understand symbols to indicate
exhaust status and control (Fig 2).
The engine aftertreatment systems on our large diameter blasthole rigs such as Pit Viper and DM rigs follow the same principles. As a rule, urea consumption amounts to 2–3% of a rig’s diesel consumption but on the Pit Viper the tank is sized to be 5% of the total, so if the rig has a 380-liter diesel tank, it will have a 20-liter urea tank.
A gauge or level indicator shows the percentage of urea remaining in the tank and ISO symbols and lamps indicate potential problems such as high exhaust system temperatures or disabled exhaust cleaning/regeneration.
DEF is not optional!
The urea tank should be refilled every time the rig is refueled. However, operators should make sure that the gauge never drops below the recommended level. If the engine should run out of urea fluid, several warnings will be displayed on the panel before the engine will shut down automatically.
In this context it must be emphasized that the DEF additive is not optional – it is essential. DEF is as important as the diesel fuel and witthout it the engines will simply not operate.
Furthermore, DEF quality sensors will prevent water or lesser quality DEF from being used. Customers who may be unsure of whether their equipment is Tier 4 Final compliant can contact their local Atlas Copco Customer Center. One thing is certain, though. The transition to Tier 4 Final is good news for everyone.
Epiroc operated under the trademark “Atlas Copco” prior to January 1, 2018.