Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and NH3.The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurizat...Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and NH3.The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurization(WFGD) process, as well as the effect of desulfurization parameters, were investigated in an experimental system equipped with a simulated SCR flue gas generation system and a limestone-based WFGD system.The results indicate that the ammonium sulfate aerosols and ammonia slip in the flue gas from SCR can be partly removed by slurry scrubbing, while the entrainment and evaporation of desulfurization slurry with accumulated NH4+will generate new ammoniumcontaining particles and gaseous ammonia.The ammonium-containing particles formed by desulfurization are not only derived from the entrainment of slurry droplets, but also from the re-condensation of gaseous ammonia generated by slurry evaporation.Therefore,even if the concentration of NH4+in the desulfurization slurry is quite low, a high level of NH4+was still contained in the fine particles at the outlet of the scrubber.When the accumulated NH4+in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH3 to NH4+and increased the additional emission of primary NH4+aerosols.With the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH4+emitted from entrainment and evaporation of the desulfurization slurry decreased.In addition, the volatile ammonia concentration after the WFGD system was reduced with the decrease of the NH4+concentration and p H values of the slurry.展开更多
The close-coupled selective catalytic reduction(cc-SCR)catalyst is an effective technology to reduce tailpipe NOx emission during cold start.This paper investigated the optimal ammonia storage under steady and transie...The close-coupled selective catalytic reduction(cc-SCR)catalyst is an effective technology to reduce tailpipe NOx emission during cold start.This paper investigated the optimal ammonia storage under steady and transient state in the cc-SCR.The study showed that a trade-off between NOx conversion efficiency and ammonia slip is observed on the pareto solutions under steady state,and the optimal ammonia storage is calculated with ammonia slip less than 10μL/L based on the ChinaⅥemission legislation.The rapid temperature increase will lead to severe ammonia slip in the transient test cycle.A simplified 0-D calculation method on ammonia slip under transient state is proposed based on kinetic model of ammonia adsorption and desorption.In addition,the effect of ammonia storage,catalyst temperature and temperature increasing rate on ammonia slip are analyzed.The optimal ammonia storage is calculated with maximum ammonia slip less than 100μL/L according to the oxidation efficiency of ammonia slip catalyst(ASC)downstream cc-SCR.It was found that the optimal ammonia storage under transient state is much lower than that under steady state in cc-SCR at lower temperature,and a phase diagram is established to analyze the influence of temperature and temperature increasing rate on optimal ammonia storage.展开更多
为研究不同海拔下SCR系统性能,分别在80、90、100 k Pa大气压力下对一台满足国五排放标准的高压共轨柴油机进行性能与排放试验,以研究排气温度、排气流量和海拔变化对NO_(x)转化率和NH_(3)泄漏量的影响。结果表明:在排气流量为350 kg/h...为研究不同海拔下SCR系统性能,分别在80、90、100 k Pa大气压力下对一台满足国五排放标准的高压共轨柴油机进行性能与排放试验,以研究排气温度、排气流量和海拔变化对NO_(x)转化率和NH_(3)泄漏量的影响。结果表明:在排气流量为350 kg/h情况下,NO_(x)转化率随排气温度升高呈现先增后减的趋势,不同温度下NO_(x)转化率最大差值为43.4百分点;NH_(3)泄漏量随着温度的升高大体上呈下降趋势,不同温度下NH_(3)泄漏量最大差值为328×10^(-6);NO_(x)转化率随排气流量升高呈现先增后减的趋势,在250℃时,不同排气流量下NO_(x)转化效率最大相差21.5百分点;NH_(3)泄漏量随排气流量的增大而增加,在250℃时,不同排气流量下NH_(3)泄漏量最大差值为90.8×10^(-6)。相同工况下,海拔越高,NO_(x)转化率越高,NH_(3)泄漏量越小,大气压力为80和100 k Pa下NO_(x)转化率最大相差20.1百分点,NH_(3)泄漏量最大相差54.6×10^(-6)。展开更多
基金supported by the National Natural Science Foundation of China(Nos.51576039 and 51576039).
文摘Selective catalytic reduction(SCR) denitration may increase the emission of NH4+and NH3.The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurization(WFGD) process, as well as the effect of desulfurization parameters, were investigated in an experimental system equipped with a simulated SCR flue gas generation system and a limestone-based WFGD system.The results indicate that the ammonium sulfate aerosols and ammonia slip in the flue gas from SCR can be partly removed by slurry scrubbing, while the entrainment and evaporation of desulfurization slurry with accumulated NH4+will generate new ammoniumcontaining particles and gaseous ammonia.The ammonium-containing particles formed by desulfurization are not only derived from the entrainment of slurry droplets, but also from the re-condensation of gaseous ammonia generated by slurry evaporation.Therefore,even if the concentration of NH4+in the desulfurization slurry is quite low, a high level of NH4+was still contained in the fine particles at the outlet of the scrubber.When the accumulated NH4+in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH3 to NH4+and increased the additional emission of primary NH4+aerosols.With the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH4+emitted from entrainment and evaporation of the desulfurization slurry decreased.In addition, the volatile ammonia concentration after the WFGD system was reduced with the decrease of the NH4+concentration and p H values of the slurry.
基金supported by the National Natural Science Foundation of China(No.51976100)the co-founding of FAW Jiefang Automobile Co.,Ltd.Wuxi Diesel Engine Factory,Saudi Aramco Technologies CompanyShandong Chambroad Petrochemicals Co.,Ltd.with the project“Fuel and Engine Co-optimization for high Efficiency and Net-Zero Emission Heavy-duty Engine”。
文摘The close-coupled selective catalytic reduction(cc-SCR)catalyst is an effective technology to reduce tailpipe NOx emission during cold start.This paper investigated the optimal ammonia storage under steady and transient state in the cc-SCR.The study showed that a trade-off between NOx conversion efficiency and ammonia slip is observed on the pareto solutions under steady state,and the optimal ammonia storage is calculated with ammonia slip less than 10μL/L based on the ChinaⅥemission legislation.The rapid temperature increase will lead to severe ammonia slip in the transient test cycle.A simplified 0-D calculation method on ammonia slip under transient state is proposed based on kinetic model of ammonia adsorption and desorption.In addition,the effect of ammonia storage,catalyst temperature and temperature increasing rate on ammonia slip are analyzed.The optimal ammonia storage is calculated with maximum ammonia slip less than 100μL/L according to the oxidation efficiency of ammonia slip catalyst(ASC)downstream cc-SCR.It was found that the optimal ammonia storage under transient state is much lower than that under steady state in cc-SCR at lower temperature,and a phase diagram is established to analyze the influence of temperature and temperature increasing rate on optimal ammonia storage.
文摘为研究不同海拔下SCR系统性能,分别在80、90、100 k Pa大气压力下对一台满足国五排放标准的高压共轨柴油机进行性能与排放试验,以研究排气温度、排气流量和海拔变化对NO_(x)转化率和NH_(3)泄漏量的影响。结果表明:在排气流量为350 kg/h情况下,NO_(x)转化率随排气温度升高呈现先增后减的趋势,不同温度下NO_(x)转化率最大差值为43.4百分点;NH_(3)泄漏量随着温度的升高大体上呈下降趋势,不同温度下NH_(3)泄漏量最大差值为328×10^(-6);NO_(x)转化率随排气流量升高呈现先增后减的趋势,在250℃时,不同排气流量下NO_(x)转化效率最大相差21.5百分点;NH_(3)泄漏量随排气流量的增大而增加,在250℃时,不同排气流量下NH_(3)泄漏量最大差值为90.8×10^(-6)。相同工况下,海拔越高,NO_(x)转化率越高,NH_(3)泄漏量越小,大气压力为80和100 k Pa下NO_(x)转化率最大相差20.1百分点,NH_(3)泄漏量最大相差54.6×10^(-6)。
