Roland Nilsson is a Swedish contractor who has worked in the forest for about 40 years. He currently runs Fågelstigens Skog AB and has three employees. In June 2011 he took delivery of his new Komatsu 931.1 harvester with its SCR-based E3-Power engine. Roland's experience as regards fuel consumption is very favourable. “We conducted a thorough review of the operations reports after 800 hours, and the favourable outcome has been maintained since then. On average, we've reduced our fuel consumption by 2-3 litres an hour. And with continually increasing diesel prices, fuel costs are an increasingly important piece of the puzzle,” says Nilsson.
All forest machine manufacturers need to consider the continually increasing operating costs for fuel and the increasingly strict legislation governing particulate matter and nitrogen oxide engine emissions. This requires refined engine and emission control technology.
The environmental requirements of emission legislation in the EU and the USA have led to the development of two different types of emission control technologies: CEGR and SCR. The choice between the traditional EGR/CEGR technology and the refined SCR technology currently divides the forest machine industry into two camps, with all machine manufacturers except John Deere and Rottne having chosen the SCR technology where emission control takes place after and outside the engine's combustion process.
“Today, all experts agree that SCR, Selective Catalytic Reduction, is the only technology that is actually capable of fulfilling the final emission requirements that will come into effect in 2014-2015. This is mostly due to NOx reduction, where SCR is undoubtedly the more effective solution. This has, for example, made most truck manufacturers change plans and switch to SCR,” explains Ola Boström, Technology Manager at Komatsu Forest.
The emission control technology in Komatsu Forest’s new forest machines is SCR-based. It enables the construction of highly efficient engines able to deliver high performance, high torque and low fuel consumption. Komatsu Forest’s new E3-Power engine generation is also characterised by optimisation based on maximum fuel combustion for the best possible efficiency. Essentially, the SCR technique achieves a reduction in nitrogen emissions by installing a catalytic converter after the engine in the exhaust system and adding a special liquid –DEF or Diesel Exhaust Fluid – to the exhaust system.
The major advantage of SCR is that the technology is based on maximum combustion of oxygen and diesel in the combustion chamber. This ensures optimal utilisation of the engine and the fuel, which is not the case with the alternative system, CEGR, which injects the exhaust gases into the combustion chamber a second time, resulting in less effective combustion.
Facts: E3-Power Engine Concept
The new engine concept is called E3-Power, with the three Es standing for Environmental, Economical and Efficient. Three prerequisites for an engine that is good for the environment and its owner. E3-Power fulfils strict emission requirements and reduces fuel consumption while delivering higher engine performance. SCR is an emission control technology with which particulates are reduced during combustion while NOx is reduced afterwards outside of the combustion process. This optimises the combustion process, guaranteeing both maximum engine performance and lower fuel consumption. What's more, the engine is less sensitive to lower quality diesel. NOx reduction takes place after combustion through the use of a urea solution (DEF, Diesel Exhaust Fluid) and a catalytic converter. In an electronically controlled process, the DEF is injected into the exhaust system just before the catalytic converter. When the mixture of exhaust gases and DEF passes through the catalytic converter the nitrogen oxides are converted into harmless nitrogen and water vapour.