| The pollution problem of non-road mobile source are attracting more and more public and governors' attention nowadays with the continuous worsening of the atmospheric pollution problem and the improvement of the delicacy management requirements of the emission source.There is an urgent need for more stringent control on construction machinery,one of non-road mobile source,because of the backward standard,insufficient maintenance,poor-quality fuel and high stand-alone emission,construction machinery has a great impact on public health and the atmospheric environment.However,the existing emission factors and source profiles data are not sufficient to support the delicacy management of construction machinery source.Therefore,we used in-site test to obtain the exhaust gas flow and gaseous and particulate emission data of main construction machinery types,loaders,forklifts,excavators and bulldozers(21 in total),in the actual idling,driving and operating conditions.The machineries' calculated emission factors and measured components data in different operation condition were given in detail and the emission characteristics of the machinery were analyzed through it.By analyzing the mechanical exhaust gas data and fuel tested data,the classification characteristics of mechanical exhaust gas and fuel products were obtained.The fuel consumption rate is related to the mechanical power and load,and the variation trends of pollutants' instantaneous emission rate were consistent with the fuel consumption rate.The average fuel consumption rate of the loaders,forklifts,excavators and bulldozers were 0.48,0.45,2.00 and 0.48 g/s respectively.Electron microscopy analysis of PM2.5 in idling condition showed that there was a certain similarity in appearances between the same types of machinery.The fuel testing found that some samples exceed the limiting value of the standard in sulfur content and moisture content.Four kinds of machines,loaders,forklifts,excavators and bulldozers,were tested using the on-road test system,and emission data of SO2.CO.NO.NO2.NOx and PM2.5 were obtained and then the emission factors were calculated.The average emission factors of SO2 of loaders,forklifts,excavators and bulldozers were 0.7,0.8,1.0 and 1.7 g kg-1 fuel respectively,the average emission factors of CO were 23.8,24.1,12.9 and 31.0 g·kg-1 fuel respectively,NO were 32.8,26.7,31.3 and 34.1 g·kg-1 fuel respectively,NO2 were 10.1,10.2,6.6 and 11.7 g·kg-1 fuel respectively,NOx were 42.9,36.9,37.9 and 45.8 g·kg-1 fuel respectively,PM2.5 were 3.6,2.7,3.7 and 5.0 g·kg'1 fuel respectively.Deeper analysis of the emission characteristics of the pollutants were given furthermore.Through the comparison,it was found that there were certain differences between the results of this study and others,while it's within a reasonable range.Including components of alkanes,alkenes,alkynes and aromatic hydrocarbons,57 in total,were identified in VOCs component analysis.It was found that C2 and C3 were the main carbon components of VOCs and the major organic components were ethylene,acetylene and propylene.Components of OC,EC,water soluble ions and inorganic elements of the PM2.5 were identified,and then the emission components of the PM2.5 were obtained.Average emission factors of OC of loaders,forklifts,excavators and bulldozers were 2.0,1.4,2.5 and 3.7 g·kg-1 fuel respectively,emission factors of EC were 0.9,1.0,0.5and 0.8 g·kg-1 fuel respectively.O C and EC accounted for a highest proportion of PM2.5.Due to the effects of fuel,air-fuel ratio and engine combustion temperature,the ratio of OC to EC of different machines differed greatly.NO3",PO43" and SO42" were the most important contributor in water soluble ion and Ca,Mg,Na and Fe were the most important contributor in inorganic elements.Although water soluble ions and inorganic elements accounted for a small proportion of PM2.5,had a great impact on human health. |
PDF Full Text Request