Egr scr long text

EGR or SCR? Komptech mobile machines work hard every day, and are environment-friendly while they do it. The use of the latest generation engines from our engine supplier Caterpillar markedly improves the air quality around the machines.

Since 1996 regulatory authorities have continually tightened the limits on exhaust emissions for the diesel engines in our mobile machines.

The current and upcoming new exhaust Stages are aimed primarily at reducing nitrogen oxide and particle levels. The first three exhaust Stages (1 to 3a) could be met through engine design changes.

The massive reductions in nitrogen oxide and particulates in the current Stage 3b standard and upcoming

EXHAUST SCRUBBING WITH PARTICULATES FILTER (EGR) In EGR technology, some of the engine exhaust is injected into the intake air.

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TECHNOLOGY

ADBLUE速 (SCR) In SCR, the engine combustion process is unchanged. The soot particulates in the exhaust remain under the mandated limits, but nitrogen oxide is excessive and must be removed. It is converted to nitrogen with the aid of a urea

SCR Technology

Urea tank

Dosing and control unit Injector

DOC Turbo charger

Due to the lower proportion of oxygen, the fuel does not burn completely and the temperatures in the cylinders are lower. This reduces the amount of nitrogen oxide that is formed. However, it leads to the formation of soot particles, which must subsequently be filtered out by a particulates filter in order to stay within mandated limits.

During operation, the filter is regularly regenerated by burning out the soot.

This regeneration does not reduce the engine output, so that machine throughput remains at a constant high level.

Intercooler

DOC Diesel Oxidation Catalysator DPF Diesel Particulate Filter

Intercooler

EGR-Cooler

EGR Technology

Stage 4 can only be achieved outside the engine. For Stage 3b, two technologies have been developed for exhaust cleaning, EGR (Exhaust Gas Recirculation) and SCR (Selective Catalytic Reduction).

To meet the mandated standards, all manufacturers in the industry have to use one or the other of these technologies. Komptech is continuing to rely on the proven quality of Caterpillar速 engines, so that customers can continue to enjoy worldwide service and top Komptech quality. Caterpillar uses EGR to meet exhaust standards, meaning that running a Stage 3b or 4 engine requires no extra effort on the part of users.

DPF

DOC SCR-CAT Turbo charger

DOC Diesel Oxidation Catalysator SCR-CAT Selective Catalytic Reduction-Catalysator

FAQs With such a major shift, there are bound to be questions.

Komptech has collected the most common and urgent questions and their answers.

What are exhaust standards called in Europe and the US? Since 1996 the US Environmental Protection Agency (EPA) and the European Union have mandated tighter and tighter exhaust emissions, to improve air quality.

The currently valid standards are Stage 3b in Europe and Tier 4i in the US. However, these are only a transition phase and will be replaced by Stage 4 and Tier 4f for most of our mobile machines in 2014. solution (known by the trade name AdBlue速), which takes the form of a liquid additive. Most engines with SCR technology can be run without urea, but the engine control causes them to operate at reduced power.

WHICH METHOD IS BEST? The advantages and disadvantages of EGR and SCR technologies are the subject of ongoing lively discussion.

Neither has a clear lead in terms of fuel efficiency or costs.

Fuel consumption is highly dependent on the load spectrum of the machine.

Calculations with currently available engine performance maps show that for Komptech applications, neither of the two methods is clearly better than the other. Therefore, with customer utility in mind Komptech has opted for EGR, since it requires no extra consumable to be added to the engine.

Finally, it should be noted that the engine is only one part of overall machine efficiency. Komptech machines feature a comprehensive efficiency design approach, which keeps overall operating costs at the lowest possible level which providing excellent functionality.

What do these designations mean?

Stage 3b / Tier 4i are the current exhaust limits. Stage 4 / Tier 4f will come into force in 2014, mandating further reductions in particulates and nitrogen oxide.

When does which standard come into force?

Stage 3b / Tier 4i have been in force since January 1, 2011.

Stage 4 / Tier 4f will come into force for the 130 - 560 kW power range on January 1, 2014.

Tier 4f in the US will come into force for the +560 kW power range on January 1, 2015. In Europe, this power range will not be regulated.

What technologies are offered to meet these standards?

Two exhaust treatment systems have developed, exhaust gas recirculation with diesel particulate filter (EGR) and urea injection (SCR).

What are the pros and cons?

The advantages and disadvantages of each are the subject of vigorous debate. Neither has a clear lead in terms of fuel efficiency or costs. However, EGR requires no additional additive, which makes maintenance less costly for the operator.

What do buyers of new machines need to consider regarding the new exhaust standard?

As we are currently in a transitional period, Komptech offers both Stage 3a and Stage 3b engines.

The customer must decide on the advantages and disadvantages of the two engine generations.

Both are legal to buy and operate.

How will the new standards impact purchase and operating costs in comparison with Stage 3a?

The much greater exhaust treatment effort required to meet Stage 3b brings considerably greater costs. With EGR systems the diesel particulate filter will need to be changed every 5000 operating hours. With SCR urea will have to be constantly refilled, as an additional consumable.

What do the new standards mean for the resale value of used machines?

Machines with exhaust treatment systems can only be sold in countries where those exhaust standards are in place. In other countries, the almost sulphur-free fuel required to operate them is not available.

TECHNOLOGY

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