Retrofit emission control devices (RECDs) primarily work by capturing and reducing harmful emissions like particulate matter (PM), carbon monoxide (CO), and hydrocarbons (HC) from diesel generator exhaust. They achieve this through a combination of filtration, chemical reactions, and catalytic processes. Here's a more detailed explanation of the working principle:
- 1. Particulate Matter Capture:RECDs often use diesel particulate filters (DPFs) to capture particulate matter (PM), including soot and ash, from the exhaust.
- 2. Oxidation:An oxidation catalyst converts harmful gases like carbon monoxide (CO) and unburned hydrocarbons (HC) into less harmful carbon dioxide (CO2) and water.
- 3. Selective Catalytic Reduction (SCR):In some devices, SCR technology uses a urea-based solution to reduce nitrogen oxides (NOx) into nitrogen and water.
- 4. Regeneration:The collected particulate matter in the DPF is periodically burned off (regeneration) to clean the filter, ensuring continued efficient operation.
- 5. Electrostatic Precipitation (ESP):Some RECDs, like those based on electrostatic precipitation (ESP), use electrical charges to attract and capture particulate matter, which is then removed using a scraping mechanism.
In summary, RECDs utilize a combination of filtration, chemical conversion, and catalytic processes to significantly reduce emissions from diesel generators, making them compliant with environmental regulations.