DPF particulate filter

The DPF diesel particulate trap installed on diesel generators is a ceramic filter installed in the emission system of diesel engines, which can filter and capture particulate emissions before they enter the atmosphere. The particulate trap can reduce the soot generated by the engine by more than 90%, and the captured particulate emissions are subsequently burned out during the operation of the generator set.

1. Working principle of DPF

The basic working principle of DPF diesel particulate filter is to spray metal platinum, rhodium, palladium and other heavy metal substances on the diesel particulate filter. The black smoke containing carbon particles emitted by the diesel engine enters the engine exhaust particulate filter through a special exhaust pipe, and passes through its densely arranged bag filter to adsorb the carbon particles onto the filter made of metal fiber felt. Thus reducing the direct emission of these particles into the atmosphere through the exhaust system and improving the quality of exhaust emissions from the generator set. The appearance structure is shown in Figure 1.

Figure 1 Outline drawing of diesel engine DPF particulate filter

2. Working principle of DPF+SCR

The "Two in One" technology on the particulate filter involves coating the SCR catalyst onto the DPF carrier, integrating the functions of SCR and DPF into one. This can effectively reduce costs and minimize the installation space of the system. However, compared to traditional DPF structures based on CDPF regeneration technology and FBC regeneration technology, DPF structures based on "two in one" technology require larger porosity and average pore diameter. Due to the fast heat release rate based on FBC regeneration technology, the thermal shock to DPF is relatively large. For this situation, design measures such as reducing mesh size, increasing wall thickness, and reducing porosity and average pore diameter are generally used to increase the thermal capacity of DPF, thereby reducing its maximum temperature and temperature gradient during "Drop in Idle" operation. CDPF technology can effectively reduce the temperature during DPF regeneration, which helps improve fuel economy; But generally, the amount of catalyst coating is not very large, 5-10g/L. Therefore, DPF applied to CDPF technology requires moderate porosity and average pore diameter.

Based on the "two in one" technology, catalyst coating amounts of up to 90-220g/L or even higher are often required. This will inevitably lead to an increase in the pressure difference of the DPF, deteriorating fuel economy. Therefore, designing a high porosity and large average pore diameter DPF to meet the requirements of high coating volume and low back pressure.

Figure 2 Outline drawing of selective catalytic reduction (SCR) system (two in one)