We see advantages to both the cooled exhaust gas recirculation (CEGR) technology and the selective catalytic reduction (SCR) technology, depending on engine size and load, and also application demands. Our Tier 4 solution integrates with our engine, hydraulic and electronic technologies in order to achieve the required reduction in pollutants at the lowest operating costs – and guarantee the high productivity and performance you expect from Kobelco excavators.

CEGR provides a user-friendly solution without any change in the operation of the machines. This solution relies on an exhaust filter system to remove particulate matter (PM) from the exhaust. By lowering the combustion temperature with an exhaust gas recirculation system, CEGR reduces the production of nitrogen oxides (NOx) inside the engine. CEGR provides performance with exceptional durability and low maintenance costs.

The main components of the CEGR system are the exhaust gas recirculation valve, exhaust gas recirculation cooler, diesel oxidation catalyst (DOC), diesel particulate filter (DPF) and, in some cases, a regeneration burner.

The diesel particulate filter (DPF) is designed to last for thousands of hours, so there will be very little effect on maintenance. If the filter needs to be changed, on machines with particularly heavy work schedules or long life, this is easy to do, as the DPF system is very accessible.

SCR is an after-treatment system that is separate from the main engine function. This technology enhances engine performance without compromising horsepower or torque. The SCR after-treatment system transforms the nitrogen oxides (NOx) produced during the combustion process into nitrogen and water, which occur naturally in the atmosphere, through a chemical reaction with a diesel exhaust fluid (DEF). SCR technology is extremely fuel efficient because it allows the engine to generate maximum power and optimizes the combustion process.

The main components of the SCR system are the supply module, diesel exhaust fluid (DEF) tank, dosing module and SCR catalyst.

DEF is a colorless and non-toxic solution of 67.5 percent water and 32.5 percent automotive-grade urea. The U.S. Environmental Protection Agency (EPA) classifies DEF as “non-hazardous.”

DEF is not a dangerous substance for transportation, however, it must be transported and stored separately from nitrites.

Transportation should be made in insulated tanks or on plastic tank pallets (IBC). Storage Tanks should be made from a suitable material of construction, this could either be a resilient plastic (HDPE for example) or a suitable grade of Stainless Steel. Some tanks can be lined but it is important that the lining/coating is not only suitable but is also checked periodically for deterioration. Regular screening of the DEF taken from the storage tank will determine these factors.

SCR technology has been used in automotive applications for several years in Europe and is currently being introduced in North America to meet EPA 2010 emissions requirements for heavy-duty diesel engines for on-road applications.

You just need to refill the diesel exhaust fluid (DEF) tank when you refuel or when you’re checking fluid levels. A warning light will signal that your DEF tank is running low.

The DEF tank capacity will be determined for each Kobelco excavator model to ensure that every refill of DEF is sufficient to last at least as long as four refills of diesel, which is enough for an average of two weeks at medium-to-heavy work cycles. The DEF tank size is approximately 10% of the fuel tank size, depending on the product.

If you attempt to operate the excavator on an empty DEF tank, you will notice a degradation of equipment performance, followed by the inability to start the engine.

Kobelco’s Tier 4 solutions integrate each machine’s engine, hydraulic and electronic systems in order to optimize their performance and efficiency. Excavators with selective catalytic reduction (SCR) technology are inherently fuel efficient, as combustion is optimized for maximum efficiency.

Some states in the US have stricter emission regulations than the EPA requirements.  Some municipalities even require meeting these stricter guidelines to participate in the bidding process for government contracts.

Small quantities of DEF are introduced into the exhaust stream and, when mixed with the nitrogen oxide (NOx) emissions, changes into harmless nitrogen gas and water vapor. Nitrogen makes up 78 percent of the air we breathe.

DEF will be available at Kobelco dealerships in North America.

DEF should be stored at temperatures between 12° F (-11° C) and 86° F (30° C).

The engine coolant warms the DEF inside the tank, which is designed to stand up to freezing temperatures. At particularly low temperatures, if the DEF reaches its freezing point (12° F/-11° C), the engine will run while the selective catalytic reduction (SCR) system is de-icing and the excavator will operate normally. DEF is easily thawed as the engine warms up, without the fluid losing any of its effectiveness.

There is not a drain to the electrical system other than the temperature sensor because the DEF tank is heated by coolant.

Urea is currently used in the agriculture, cosmetics and food industries. It is also used as a nutrient for effluent wastewater treatment and fermentation processes.