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OTC ' 14: Cummins introduces first EPA-certified Tier 4 engine 

HOUSTON -- Cummins Inc. has announced that the latest generation QSK50 engine with Selective Catalytic Reduction (SCR) aftertreatment designed for well servicing applications has successfully completed an intensive program of Tier 4 Final low emissions validation and severe duty field testing, totaling 33,000 hours in duration.

The 50-liter V16 is expected to be the first engine with a 1500 hp-to-2500 hp output (1103-1864 kW) certified by the U.S. Environmental Protection Agency (EPA) to meet Tier 4 Final emissions regulations, more than six months ahead of the Jan. 1, 2015, effective date.

With this early compliance advantage, the QSK50 will move from current pre-production build to full production status by mid-year 2014, enabling Tier 4 Final compliant rigs to enter service aligned with the first requirements in the industry for very low emissions operations. The engine and SCR aftertreatment will commence production as a fully proven system, following a long period of severe duty field testing installed in well servicing rigs operating during extremes of high heat, dust and high humidity below freezing temperatures.

"The QSK50 is a very popular choice with well servicing operators, and the latest Tier 4 Final engine with integrated SCR aftertreatment will continue an enviable reputation for dependability, fuel efficiency and power performance," said Dave Porter, Director - Cummins Oil and Gas Business.

"The QSK50 goes beyond just meeting Tier 4 Final low-emissions levels, as the engine also offers enhanced durability, reduces fuel consumption, extends oil service intervals to 500 hours and provides a faster response to load demands. The results from our well servicing field tests are very impressive, and add up to a very compelling opportunity for operators to improve their pumping productivity by specifying the Tier 4 Final engine," added Porter.

The QSK50 Tier 4 Final engine retains all the design simplicity of the Tier 2 QSK50 and offers a near-identical installation envelope. The SCR system has been designed by Cummins with the same "drop-in" space claim to that of silencers typically used on pumping rigs today. The SCR is a fully passive, flow-through system and requires no scheduled service.

Design upgrades to both the QSK50 power cylinder and Modular Common Rail System (MCRS) contribute to extending engine life-to-overhaul by as much as 10 percent compared with that of the current Tier 2 engine. For Tier 4 Final, this means the QSK50 is capable of achieving 1 million gallons of fuel consumed before overhaul.

The SCR aftertreatment system is designed to achieve the same life-to-overhaul as that of the engine, specially strengthened against extreme shock loadings and vibrations.
Wastegated Turbocharging

Air handling on the QSK50 is significantly enhanced for Tier 4 Final, with the high pressure stage Cummins turbochargers incorporating a pair of fully adjustable wastegate devices. The wastegate enables a varying proportion of the exhaust gas flow to bypass the turbocharger, allowing the air flow-to-fuel ratio to be more precisely controlled, helping reduce particulate matter (PM) emissions and lower fuel consumption. The wastegate also enables a faster response to load demands across a broader engine rpm speed, helping the frac pump maintain higher flow rates and a higher pressure capability.

Tier 4 Final Proven
Emissions validation work has confirmed that the QSK50 meets the Tier 4 Final required emissions levels of 3.5 g/kW-hr for oxides of nitrogen (NOx) emissions and the 0.04 g/kW-hr level for PM, with a significant margin to spare. This means the Tier 4 Final QSK50 operates well within its comfort zone - even when working under the tough duty cycles demanded by hydraulic fracturing.

With NOx emissions removed from the exhaust by the SCR, the need for cooled Exhaust Gas Recirculation (EGR) on the engine is avoided and allows the QSK50 combustion formula to focus on PM control and reducing fuel combustion. Both the exhaust gas temperatures and in-cylinder pressure remain the same as the Tier 2 engine, enhancing uptime dependability and durability. Heat rejection also remains the same as the Tier 2 engine, with no additional cooling system capacity needed on the rig.

Operator Experience
The well servicing field test program subjected the Tier 4 Final QSK50 and SCR system to very severe, real world operating conditions. Precise data collection demonstrated that Diesel Exhaust Fluid (DEF) dosing levels for the SCR system remained at low levels while overall fuel efficiency across the entire operating duty cycle of a frac rig increased compared with that of the Tier 2 engine. In all examples, the total cost of diesel fuel and DEF was significantly reduced from the diesel only Tier 2 engine.

An additional factor in reducing fluid cost and service time is the oil service intervals and filter changes, extended to 500 hours for the Tier 4 Final engine, compared to 250 hours for the Tier 2 engine. One of the other key deliverables of the field-test program was an assessment of system reliability compared with that of previous engines.

Operators reported that the Tier 4 Final equipment uptime is every bit as impressive as what they experienced with their QSK50 Tier 2-powered rigs. Operators also commented that the cleaner, quieter and smoke-free operation of the Tier 4 Final QSK50 makes a real difference to their working environment.

QSK50 clean engine credentials are realized with an integral, service-free crankcase breather system on the engine. This helps reduce hydrocarbon emissions and eliminates oil mist, to ensure a permanently clean Tier 4 installation.

05/05/2014

 

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