Investigation On The Influence Of The Catalytic Diesel Particulate Filter Regeneration Performance

Diesel Particulate Filter?DPF?presents a high particulate matter?PM?trapping efficiency.It is one of the most efficient after technologies to reduce the PM emissions form diesel engines.The crucial problem of this technology is how to achieve a high efficiency of DPF regeneration at low temperature.Catalytic Diesel Particulate Filter?CDPF?is helpful for reducing the PM light-off temperature,so as to achieve the low-temperature regeneration of DPF and improve its regeneration efficiency.In this paper,a commercial CDPF was selected,and samples with different carbon loadings were prepared on the self-made CDPF carbon black loading device.Based on the simulated gas test platform,the effects of carbon loadings,regeneration temperature,heating rate,gas flow rate and gas composition on CDPF regeneration performance were studied.The main work content and conclusions are as follows:?1?CDPF carbon loading samples with carbon loadings of 3.2 g/L,5.0 g/L,7.0g/L and 9.0 g/L were prepared on the CDPF carbon black loading device designed and built by ourselves.The CDPF temperature programed regeneration test was carried out to explore the effect of carbon loadings and temperature-raising rate on the regeneration performance of CDPF via the simulated gas test platform,and the CO₂ concentration changes during CDPF regeneration under different carbon loadings and temperature-raising rates were analyzed.Results showed:that the regeneration of CDPF was mainly divided into three stages:the first stage mainly occurred at 250⁴00?,and the amount of carbon consume in the reaction accounted for about 34%of the total carbon,which was a long-term and slow regeneration stage;the second stage mainly occurred at400⁵00?,and the amount of carbon consumed in the reaction accounted for about1%of the total carbon,which was the transition regeneration stage;the third stage mainly occurred at 500⁶00?,the amount of carbon consumed in the reaction accounted for about 65%of the total carbon,which was a short term and rapid regeneration stage.It was observed that CO₂ concentration peak decreased in the first stage and increased in the third stage with the increasing carbon loadings.The CO₂concentration peak in the third stage gradually was found to increase with the increasing heating rate,and the regeneration duration was shortened simultaneously.?2?CDPF constant temperature regeneration tests at the selected regeneration temperatures within the range of 250⁵50??at intervals of 50??were carried out to study the effects of regeneration temperatures on the regeneration performance of CDPF.The results showed that as the regeneration temperature increased,the CDPF regeneration efficiency ratio increased.The regeneration efficiency and regeneration efficiency ratio of CDPF were increasing slowly under the temperature of 250⁴50?,while increasing rapidly within the temperature range from 450 to 550?.The maximum temperature gradient of CDPF showed a trend of first decreasing and then increasing with the increase of regeneration temperature.When the regeneration temperature was 350?,the maximum temperature gradient the bottom at 4387.5?/m.?3?CDPF constant temperature regeneration tests under the selected gas flow rates within the range of 100⁴00 mL/min?at intervals of 100 mL/min?were carried out using the simulated gas test platform,and the regeneration performance of CDPF under different gas flow rates was studied.The results showed that when the regeneration temperature was 400?and 450?,the gas flow rates have little effect on the CDPF regeneration performance.When the regeneration temperature was 500?and 550?,the maximum temperature,maximum temperature gradient and regeneration efficiency of CDPF regeneration were increased firstly and then decreased with the increase of gas flow rates.When the gas flow was 300 mL/min.The three values within the two temperature range reached the top at 599.1?,6457.3?/m,62.5%and 651.5?,6944.2?/m,67.2%,respectively.?4?Based on the simulated gas test platform,the CDPF constant temperature regeneration tests were carried out under the atmosphere of O₂/N₂,O₂/NO₂/N₂,O₂/NO/NO₂/N₂,O₂/NO/NO₂/H₂O?where N₂ was the balance gas?,the effects of different gas components and concentrations on CDPF regeneration performance were studied.The results showed that when the regeneration temperature was 550?,evaluation indicators for regeneration performance,including the maximum temperature,maximum temperature gradient,regeneration efficiency and regeneration efficiency ratio of CDPF regeneration,gradually increased with the increase of O₂concentration under the O₂/N₂ atmosphere.Those evaluation indicators reached the maximum value under the O₂ concentration of 6%,while remained unchanged basically when further increasing the O₂ concentration.,It was found that CDPF regeneration was inhibited after NO₂ was added when O₂ concentration was 10%,and the inhibitory effect was weak under 500×10^-6 v/v NO₂.The evaluation indicators for regeneration performance showed a trend of first increasing and then decreasing with the increase of the ratio of NO to NO₂ in the O₂/NO/NO₂/N₂ atmosphere,and they all reached the maximum when the ratio of NO to NO₂ was 1.In the atmosphere of O₂/NO/NO₂/H₂O/N₂,the maximum temperature and maximum temperature gradient during the regeneration of CDPF increased first and then tended to stabilize,while the regeneration efficiency and regeneration efficiency ratio remained unchanged basically with the increase of H₂O content.The regeneration efficiency reached 96.7%with 10%H₂O.