Particulates or soot particles are the most visible of the pollutants emitted from the exhaust of a diesel engine, they consist of large carbon particles with other attached and absorbed chemicals. Diesel particulates, in addition to being visible, are toxic and carcinogenic, and the smaller particle of less than 10 microns (known as PM10’s) can penetrate deep into the lungs causing respiratory problems. With the increased use of diesel engines, the increase in airborne particles is becoming an increasing environmental issue.
Current international legislation requires that all new engines (stage IIIB on) have some means of reducing particulate emissions and are commonly being fitted with filters. Retrofitting with a Diesel Particulate Filter (DPF) can bring many older engines up to these latest standards of cleanliness.
These solid emissions can be effectively reduced by filtration of the exhaust. The most effective and practical method is by using a ceramic filter substrate, usually silicone carbide with micro porous walls. This traps the solid particles but allows the cleaner gasses to escape through the wall and is vented towards the exhaust outlet. The collected soot builds up within the filter which will eventually block resulting in a build up of engine back-pressure unless it is removed, this is achieved by a process known as regeneration.
Regeneration is achieved by “burning” the collected soot within the filter, either actively or passively. This is done by raising the temperature to a point where the carbon particles combine with free oxygen to form CO2.
In an active system a separate, either electrical or a fuel burner is used to raise the temperature to around 600 degrees C to create the oxidation effect. In the passive system the heat of the engines exhaust gas is used in conjunction with a special catalytic coating on the filter to achieve the same result, and can be achieved at much lower temperatures.
Western Tydens can offer from CDTi both active and passive systems.
CDTi systems meet international standards and have been tested by organisations such as VERT, EST or EPA.