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污染控制技术及原理

Assessment of the environmental effects of the compressed natural gas bus fleet in Beijing

摘要：经过对北京市2007年公交车队的详细技术构成与实际运营情况的调研,发现北京市公交车队的主力车型为国三和国四车辆,应用修正的COPERTIV模型计算出北京市各技术水平的汽油、柴油和压缩天然气(CNG)公交车的排放因子.2007年北京市国三CNG公交车PM_2.5和NO_x单车排放因子分别比国三柴油车削减了97%和30%,而公交车队中排放控制最为严格的EEV天然气公交车的PM_2.5和NO_x单车排放因子分别比国四柴油公交车削减了93%和69%.但由于CNG公交车的CH₄排放水平较高,导致CNG公交车的总碳氢化合物(THC)单车排放因子显著高于相近控制水平的柴油公交车.在单车排放水平的基础上建立了北京市公交车排放清单,2007年北京市公交车排放的CO、NMHC、THC、NO_x和PM_2.5分别为9051t、955t、1222t、8553t和161t.与没有CNG公交车的对照情景进行比较,在使用了CNG公交车后,2007年北京市公交车CO、NMHC、NO_x和PM_2.5排放总量分别削减了293t、62t、775t和33t,削减比例分别为3.1%、6.1%、8.3%和17.2%.2007年北京市通过在公交车队中使用CNG车辆共减少了柴油消耗量约5.0×10⁴t,相当于北京市各行业柴油总消耗量的2.6%.2007年北京市公交车尾气排放的温室气体的CO₂当量为8.3×105t,比不使用CNG车辆的情景略微增加了2.4%.

Abstract：Based on an investigation of the bus fleet configuration and operation situation in Beijing in 2007,we identified that Euro IIIand Euro IVvehicles are the most common bus models. The modified COPERT IVmodel was used to estimate emission factors for gasoline,diesel and compressed natural gas (CNG) buses meeting different emission control standards in Beijing. The PM_2.5 and NO_x emission factors of the Euro III CNGbus are reduced by 97% and 30% as compared to the Euro IIIdiesel bus. The PM_2.5 and NO_x emission factors of enhanced environmentally-friendly vehicle (EEV) CNGbuses are reduced by 93% and 69% as compared to the Euro IVdiesel bus. Because the CH₄ emission factor of CNGbuses is much higher than diesel buses,the THCemission factor of a CNG bus is significantly higher than a diesel bus of similar control standard. Abus emission inventory was built based on these emission factors. The bus emissions in Beijing in 2007 were 9051 t CO,955 t NMHC,1222 t THC,8553 t NO_x and 161 t PM_2.5. By using CNGbuses,the emission of CO,NMHC,NO_x and PM_2.5 has been reduced by 293 t,62 t,775 t and 33 t,or 3.1%,6.1%,8.3% and 17.2% of total bus emissions,respectively. In 2007,the operation of CNGbuses has reduced diesel consumption by 5.0×10⁴ t,which is 2.6% of the total diesel consumption in Beijing. And the CO₂ equivalent of greenhouse gas emissions of Beijing buses in 2007 was 8.3×10⁵ t; 2.4% higher than the scenario without CNG buses.