Brian Breaux explores how an engine expert is encouraging the oil & gas industry to adopt the latest in green engine technology
In January 2015 US EPA Tier 4 Final regulations, the most stringent to date driving reduction of particulate matter (PM) by 80% and oxides of nitrogen (NOx) by 45% over previous Tier 2 regulations, took effect for all new, non-road engines greater than 751hp.
Many manufacturers have been able to use the Transitional Program for Equipment Manufacturers (TPEM) to delay the introduction of Tier 4 Final compliant powered equipment, however that option expires in 2017.
Beginning January 1, 2018 all new non-road engines greater than 751hp that are purchased, must meet the Tier 4 Final regulations. To meet these requirements Cummins has chosen to use selective catalytic reduction (SCR) technology.
The company has based its Tier 4 Final emissions technology decision for these products on years of experience with SCR and exhaust gas recirculation (EGR) technology.
Although diesel exhaust fluid (DEF) is required by the SCR solution simplicity, power, performance, TCO, durability and reliability are all maintained or improved.
Cummins has a vast amount of Tier 4 Final engines in the field for the oil & gas industry. With the first US EPA Tier 4 Final complete fracturing spread operational since 2015, the firm is demonstrating that SCR is the right technology for the well servicing fracturing market and it hopes to have the same success in the drilling sector.
Its Tier 4 Final high-horsepower engines using SCR offer reduced peak cylinder pressure, lower fuel injection pressure and equivalent heat rejection when compared to Tier 2 engines, as well as other emissions technologies such as EGR and variable valve timing (VVT). Fuel injection pressure is also less as compared to other technology.
Heat rejection for the engines will be the same as Tier 2, whereas the heat rejection for EGR technology can be 30 to 60% greater than Tier 2 designs. Transient response will be the same as Tier 2 for the same displacement engine. By using SCR, the engine can operate more efficiently, producing less PM in cylinder, without the need of a DOC of DPF. Also with SCR, lower emission regulations in the future, as well as for non-attainment locations today, can be reached. EGR emissions technology cannot meet any lower emission regulations than Tier 4 Final.
Educating the oil & gas industry
Although the company is very familiar with SCR technology the oil & gas industry is just becoming familiar with the regulations and the engine changes necessary to meet them.
To help its customers prepare for this change, Cummins has designed, built and tested a drilling power module (DPM) that can be temporarily integrated into existing Tier 2 or Tier 4 equipment. This DPM allows customers first-hand experience with a Tier 4 Final compliant package on their job-site. This DPM, dubbed ‘rotating unit’, includes a Tier 4 drilling power module, cooling system and DEF system, is housed on a 40in length x 10in wide x 11in height master skid and is designed to move from site to site and customer to customer.
The QSK50 engine powering the rotating unit is rated at 1,500hp and is paired with a Kato M/N 4P8.2-2700, 600V/60Hz/0.7 PF/oversized generator for drilling duty.
The control system offers integrated engine monitoring with satellite telematics. And the installation is the same footprint as the Tier 2 DPM. The integrated 330 gallon bulk DEF system, provides as many as 15 days of runtime before DEF refill is needed.
Larger bulk DEF solutions can be used, providing longer runtime before refill.
The QSK50 offers many improvements over its Tier 2 predecessor, including improved piston ring packs to reduce blow by, new piston bowl design to increase the mixture of fuel and air and faster flame propagation for a more complete combustion.
Additionally, ahead of each turbo charger is a fully variable valve wastegate that can either control PM by optimising air/fuel ratio under all engine conditions, or control the SCR inlet temperature to increase NOx removal efficiency and reduce DEF usage.
The high-pressure common rail system (HPCR) allows as many as four separate injections per combustion cycle, to ensure more efficient combustion. Improved fuel filtration with a synthetic nano fibre media, catches sub-micron particles before they enter the into the engine’s fuel system.
Support during the design, integration, installation and operation of the rotating unit will be provided, to ensure the field trial of the DPM will offer the customer a true sense of the Tier 4 Final operational experience.
Based on its extensive past experience with SCR technology and its current success with Tier 4 Final in well servicing and drilling, Cummins believes that SCR emissions technology is the right choice for the Tier 4 Final transition.
Brian Breaux is with Cummins.