Reliable SCR dosing for the exhaust gas purification of large engines

The challenge

Manufacturers of industrial and large engines are under increasing pressure to comply with ever stricter emission limits for nitrogen oxides. For large engines - for example in shipping or industrial applications - a purely internal reduction of emissions is often not sufficient. Without reliable exhaust gas aftertreatment, there is a risk of approval problems and the loss of the engines' operational capability. At the same time, the required urea dosing must be precise, monitored and reliable in order to avoid both under- and overdosing.

The sera solution

sera supplied a dosing solution for exhaust gas aftertreatment with SCR catalytic converter, in which a urea solution is precisely injected into the exhaust gas flow from a day tank. Dosing takes place via a dosing pump from the iSTEP series and is specified via a control system depending on the load. The dosing process is monitored via pressure and volume flow sensors. Injection takes place via a nozzle lance that finely atomises the urea. In addition, the lance is supplied with compressed air to cool it and to protect the urea line from clogging due to crystallisation via a flushing function. This enables stable and reliable SCR operation.

The customer benefit

• Reliable compliance with NOx limit values for industrial and large engines
• Stable, monitored dosing process without risk of blockages
• Load-dependent, on-demand urea injection
• Increased operational reliability of exhaust gas aftertreatment

Summary

The project shows how SCR exhaust gas aftertreatment can be reliably implemented in large engines with monitored and reliable dosing systems.