Study On The Analysis Of The Organic Fraction In Condensable Particulate Matter And Its Migration And Distribution Characteristics In Coal-fired Flue Gas

Coal plays a very important role in China's energy structure under the condition of natural resources with more coal and less oil and gas in China.At present,the concentration of conventional pollutants has been significantly reduced by the utilization technology of coal while there is still no effective control method for organic pollutants emitted by coal combustion.Also,the research on the composition of organic pollutant in condensable particulate matter and its migration and distribution characteristics in the flue gas purification process is still scarce.Therefore,this article focuses on the composition analysis of condensable particulate matter in coal-fired flue gas and the influence of air pollution control devices on its migration and distribution characteristics.The main contents and conclusions of the study are summarized as follows:(1)Qualitative and quantitative analysis of organic components of condensable particulate matter in coal-fired flue gas.With the help of the Unknown Analysis software of Agilent,the organic pollutant of condensable particulates has been qualitatively analyzed and was classified into five major organic matter,namely hydrocarbons,esters,siloxanes,and heteroatoms and the others.Since the components of hydrocarbons,esters and siloxanes accounted for more than70%of the samples tested in the result of qualitatively analysis,the three types of organic pollutant were selected as the research objects for quantitative analysis.According to the existing test methods and the toxicity of organic matter,the n-alkanes and the phthalates were selected for quantitative analysis.In addition,the possible quantitative method for siloxanes was proposed.In order to understand the migration and distribution characteristics of condensed particulate matter,the alkanes and phthalates had been extracted from the raw coal.(2)The study on the composition and emission characteristics of condensable particulate matter in power station boilers.The emission characteristic of condensable particulate matter under different operating conditions was studied.The concentrations of condensable particles emitted by three coal-fired units were 13.4mg/Nm~3,9.47mg/Nm~3,9.87mg/Nm~3,respectively,which accounted more than 50%of the total particulate matter.The proportions of n-alkanes and accounted for 8.4%,6.3%and 7.1%of the condensable particulate matter while the proportions of phthalate were 1.5%,1.7%and 2.4%,respectively.The results showed that the concentration of condensable particulate matter decreased with the temperature of the flue gas decreasing.In the same,the concentration of organic components of condensable particulate matter(including n-alkanes and phthalates)was also the lowest at the lowest point of temperature which may due to the condensation which mean the condensable particulate matter convent from gas to solid with the decline in the temperature in the flue gas.Also,the results showed that the distribution of the proportion of n-alkanes in the condensable particulate matter at each sampling point was similar.Combined with the previous research results,it was further speculated that the distribution of n-alkanes in different units of the same power plant was basically the same as long as the same technological process was adopted and the coal types were similar.In addition,15 kinds of phthalates were measured at various sampling points.Considering the current restrictions on toxic phthalates in various countries,the DBP could be selected as the key component to reduce the emissions of phthalates in condensable particulate matter.(3)The study on the analysis of the organic fraction in condensable particulate matter and its migration and distribution characteristics in small industrial coal-fired boilers.Compared with large-scale coal-fired power plant boilers,small industrial boilers have lower organic unit capacity and higher levels of organic pollutant emissions.Units that have been assembled with ultra-low emissions devices could significantly reduce the emission of organic pollutant.The concentration of condensable particulates emitted by the XT unit and the FY unit was7.67mg/Nm~3 and 34.47mg/Nm~3,respectively.For the n-alkanes in condensable particulate matter,the relative proportion of each n-alkane after passing through the flue gas purification equipment was basically the same.It could be speculated that the existing flue gas purification equipment has no selectivity for the removal of n-alkanes.As for the phthalates in condensable particulate matter,attention should be paid to the restricted organics such as DBP whose proportion was relatively large in multiple samples.The dust collector had a significant effect on the removal of filterable particles and the n-alkanes and phthalates in condensable particulate matter.In the XT unit,the remove efficiency was 78.6% and 71.1% of n-alkanes and phthalate.In addition,some new air pollutions control devices had a good effect on the organic components of condensable particulate matter.