Diesel particulate filters for more than 19 KW
Retrofit diesel particulate filters for construction machines of more than 19 kW – Johnson Matthey range of DPFs
BISAF is the UK agent for Johnson Matthey’s range of retrofit emissions systems for construction machines. These include a range of filter sizes and regeneration types that mean that a system can be retrofitted to any machine, regardless of size or application. These are full flow filters that are intended for permanent installation. They are on the Energy Savings Trust register for use in the London NRMM LEZ, as well as being VERT approved.
Regeneration types include passive & active systems:
The DPF CRT/CCRT: Johnson Matthey invented the CRT which is the most widely used and successful retrofit filter technology. This uses a special catalyst in front of the filter to convert some of the NO in the exhaust gas to NO2. The NO2 reacts with the soot on the filter at normal exhaust temperatures to continually remove the particulate as it is filtered from the exhaust gas.
For this technology to work successfully, the exhaust gas needs to be above 260oC for 50% of the time. This is normally achieved when a machine uses a significant amount of power to complete tasks. The operating window can be extended to lower temperatures (50% of the time above 240oC) by using the CCRT that has a catalyst coated filter as well as the pre-catalyst.
The DPFi: This is an active system that intermittently employs electrical heating to burn off the soot from the filter. In this system, the back pressure of the filter is monitored and when this reaches a certain level the operator is notified that the filter should be regenerated.
This involves turning off the engine, connecting an external power source and waiting approximately one hour for the cycle to be completed. The monitor will inform the operator that the cycle has been completed successfully and the machine will be ready to use again.
The DPF BU: This is another active system that used a burner fuelled from the machine’s Diesel tank to burn off soot accumulated on the filter. The back pressure monitor in the cab will alert the operator when the system needs a regeneration, the operator will stop the engine and then start the burner cycle which lasts about 30 minutes before the machine is ready to be used again.
To find out about the EU Legislation and London LEZ requirements, please read here.