selective catalytic reduction

This SCR doesn’t need urea

JUNE 29, 2018 — A Danish R&D start-up has developed an SCR system that reduces diesel engine NOx emissions using diesel oil, and not urea, as the reductant. To comply with IMO

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High Pressure SCR completes certification testing

FEBRUARY 3, 2016 — Hyundai Heavy Industries (HHI), the world’s largest shipbuilder and a leading marine engine maker, reports that it has produced the world’s first High Pressure Selective Catalytic Reduction (HP

Tenneco SCR gets two DNV GL AIP certifications

The certificates cover key components of the system, including the complete dosing and control system, injectors, load sensors and the human machine interface (HMI) remote monitor, as well as catalyst and reactor hardware configurations for IMO Tier III applications.

“We’re pleased to receive this important classification. Tenneco’s high horsepower SCR technology is designed to meet IMO Tier III NOx reduction requirements that take effect in 2016 and this classification further demonstrates our readiness to deliver these solutions for ships or vessels anywhere in the world,” said Jay Kedia, Tenneco managing director, large engine.

Tenneco’s SCR aftertreatment system features a complete dosing control solution specifically designed for marine engine applications up to 7,500 kW or 10,000 hp. The system is designed to enable propulsion and auxiliary engines to meet U.S. EPA Tier 4 and IMO Tier III regulatory requirements and provide precise and reliable delivery of liquid urea via a proprietary, high-performance injector design, a precision mechatronic fluid delivery pump and customizable remote monitoring and controls.

In the past year, the company has conducted a series of validation tests to demonstrate how the system’s form, fit, function and performance capabilities can be easily integrated into a vessel’s engine and control architecture.

Most recently, through a partnership with the Texas A&M Maritime Academy, Tenneco conducted saltwater sea trials onboard the TS General Rudder in the Gulf of Mexico. Tenneco’s SCR system was installed on a 33-year old 800 horsepower, Tier 0 engine that was operational for the duration of the Academy’s summer cruise training period. Results demonstrated NOx reduction levels that kept the General Rudder compliant with today’s stringent U.S. EPA Tier 4 marine emission requirements under all operational conditions.

Tenneco conducted similar tests on a 224 ft\ training vessel in the Great Lakes in 2014. In a series of validation tests, including the ISO 8178 E2 cycle, when a similar engine was outfitted with Tenneco’s SCR system, the engine met all criteria for IMO Tier III, including NOx.
In addition to DNV GL classification, Tenneco’s high horsepower SCR system has been awarded product design classification from ABS, and is designed to meet the requirements of other major maritime classification societies including CCS, KR and Class NK.

SCR System Features

The SCR system’s modular design enables seamless integration for a broad range of engine sizes and works with electrically or mechanically controlled engines. It has been validated for durability and all components are easy to maintain and service without the need for special tools.

The fluid delivery system with dosing control software is capable of managing multiple injection points and sensors. The system can support urea flows up to 120 meters, which enables a wide array of installation options. Airless urea injection provides high dosing accuracy and consistency without the need for dedicated compressed air.

The system’s Human Machine Interface (HMI) can be accessed on the front of the fluid delivery box or remotely via a touch screen tablet. It features an easy-to-use interface to monitor and control all system parameters including but not limited to NOx reduction performance and urea concentration levels in real time. Onboard diagnostics are capable of monitoring more than 100 parameters including urea leakage, sensor faults and backpressure.

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Cat offers C280 engines that meet EPA Tier 4 limits


The EPA Tier 4 standards applied to all new U.S. flagged vessels starting in January 2014. IMO III standards will apply to all new vessels entering IMO NOx Emissions Control Areas (NECA) starting in January 2016.

The C280 engines are available in eight, 12 and 16-cylinder models spanning a power range from 2300 ˗ 5060 kW as main engines – conventional and diesel electric – and also as auxiliary generator sets. Caterpillar says that the latest models offer significant benefits over earlier units. As well as reduced emissions, they consume less fuel and have lower through-life owning and operating costs.

According to Nathan Kelly, Caterpillar Marine production definition engineer, the choice of SCR over other NOx reducing technologies, was made based on the Caterpillar commitment to customers to offer solutions that provide the highest uptime and minimize overall total lifecycle cost.

“SCR was a clear choice for us,” explains Mr. Kelly. “We have more than 160,000 Tier 4 Final and Interim engines in land-based operations using various NOx-reduction technologies. In marine applications, we specifically chose the best technology to fit the needs of our industry. We view SCR as the preferred option for the commercial marine industry. “

“The C280 is already renowned for its high uptime, reliability and durability,” he continued, “but for these Tier 4 engines our priority was to achieve the lowest lifecycle owning and operating cost. We have succeeded in this by improving engine fuel efficiency. Unlike previous emissions tiers, our Tier 4 engines can run at optimal fuel efficiency because the SCR system is in place to reduce the higher NOx output.”

He says that any concerns about the cost of the urea based Diesel Exhaust Fluid (DEF) used in SCR technology are more than offset by the improved fuel efficiency delivered.

“Unlike some other NOx reduction technologies, our engines operate without interruption even in the event of SCR failure or running out of DEF,” adds Mr. Kelly. “There is no effect to engine operation.”