典型焦化厂大气挥发性有机物排放表征分析

Characteristic Analysis of VOCs Emitted from a Typical Coking Plant

焦化行业是我国重要工业类别,但因其工艺过程复杂,所以VOCs(挥发性有机物)排放特征尚不明确.以典型机械焦化厂为研究对象,对焦炉烟囱、推焦、装煤和焦炉顶等不同排放环节进行采样,并利用GC/MS(气相色谱质谱联用仪)进行多物种分析,并对焦化厂排放VOCs的OFP(生成O3的潜势)进行探索性研究.结果表明:①焦化厂排放的VOCs包括烷烃、烯烃、炔烃、芳香烃、卤代烃和含氧VOCs等六大类,共90多个物种.②不同环节排放的ρ(VOCs)差异显著,其中,焦炉烟囱ρ(VOCs)排放量(87.1mg/m^3)最大,其次为推焦(4.0mg/m^3)、装煤(3.3mg/m^3)和焦炉顶(1.1mg/m^3).③不同环节排放的VOCs种类不同,但均以烷烃和烯烃为主,其中,焦炉烟囱排放的烯烃最多(占比达66%),装煤和推焦排放的则以烷烃为主(占比分别为42%和36%),焦炉顶排放的烷烃和烯烃相近(占比分别为31%和29%).④基于排放特征和最大增量反应活性法研究发现,焦炉烟囱是焦化厂VOCs减排的重点环节,烯烃是重点减排的物种,特别是乙烯、丙烯、丁烯和1,3-丁二烯等,但乙醛、苯、甲苯等也不容忽视.研究显示,以乙烷/丙烷/乙烯(三者质量浓度之比)为指标,可明显区分焦炉烟囱、推焦、装煤和焦炉顶等不同环节的VOCs排放.

The coking industry is an important VOCs emission source in China.Due to the complex production process,the VOCs emission characterization is lack,so a typical mechanized coking plant was selected to study.Samples were collected from coke oven chimney,coke pushing,coal charging and coke oven top.GC/MS was used to analyze the samples,and maximum increment reactivity(MIR)was used to quantify the ozone formation potential(OFP).The results show that:(1)The VOCs emitted from the coking plant mainly include alkanes,alkenes,alkynes,aromatic hydrocarbons,halogenated hydrocarbons and oxygenated VOCs,and more than 90 species.(2)The concentrations of the total volatile organic compounds generated from coking processes are significantly different.ρ(VOCs)from coke oven chimneys have the largest emissions(87.1 mg/m^3),followed by coke pushing(4.0 mg/m^3),coal charging(3.3 mg/m^3)and coke oven tops(1.1 mg/m^3).(3)The VOCs species in different coking processes are different,but mainly alkane and olefins.The coke oven chimney emits the most olefins,accounting for up to 66%,while the VOCs of the coal charging and coke pushing are dominated by alkanes(42%and 36%respectively),and the alkane and olefins emitted from coke oven top are similar(accounting for 31%and 29%).(4)Based on emission characteristics and maximum incremental reactivity studies,coke oven chimneys are the key link in the reduction of VOCs in the coking plants.Olefin is a key emission reduction species,especially ethylene,propylene,butene and 1,3-butadiene.In addition,acetaldehyde,benzene,toluene cannot be ignored.The study uses ethane/propane/ethylene characteristic ratio as an indicator to distinguish VOCs emissions from different stages such as coke oven chimney,coke pushing,coal charging and coke oven top,which are of great significance for accurate traceability of VOCs.