Abstract:

Petrochemical intermediate storage tanks are key volatile organic compounds (VOCs) emission sources which play vital roles in regional air pollution and abatement. During the working loss process, the intermediate product tank vents of refining and petrochemical processes and waste oil tanks in a petrochemical facility were sampled and measured in this study. The emission characteristics of VOCs were analyzed and speciated source profiles for specific sources were developed. The ambient photochemical reactivity were developed based on the value of OH loss rate. By virtue of the maximum increment reactivity method, ozone formation potential of sources were determined. The results suggested that level of VOCs from working loss process reaches tens of thousands mg/m³, and the corresponding emission strength ranged from 0.55g/m³ to 71.3g/m³ per material turnover. The VOCs emission characteristics differed among specific tanks, with refining process related tank and waste oil tank dominant in alkane and petrochemical tank prevailing in alkene and aromatics. The C₃—C₇ alkane, C₃—C₄ alkene, benzene, toluene and acetone were ranked as primary pollutants with highest weight percentage. The intermediate storage tank vented VOCs features in relative high photochemical reactivity (1.43×10⁴—2.37×10⁶s^-1) and OFP (2.84×10⁵—7.53×10⁷mg/m³), with waste oil tank of delayed coking process having the lowest value and heavy oil product of ethylene cracking process the highest value. The alkane and alkene were found to contribute mostly to VOCs related photochemical reactivity and OFP during the working loss process. The C₆—C₇ alkane such as methylpentane, hexane and methylcyclohexane, C₃—C₅ alkene, and xylene were recommended to give preferred control priority.

Key words: intermediate storage tank, petrochemical facility, volatile organic compounds, emission source, ozone formation potential

摘要：

中间储罐是石化企业的主要挥发性有机物（VOCs）排放源，对大气环境产生重要影响。本文对我国某石化企业炼化中间产物、污油、石化中间产物等中间储罐大呼吸过程进行了采样监测，分析了VOCs排放特征并建立了有机污染物图谱。基于OH自由基损失速率和最大增量反应活性法，分别量化了大呼吸过程大气反应活性和臭氧生成潜势（OFP）。结果表明，中间储罐大呼吸过程VOCs浓度高达数万毫克每立方米，单位体积物料周转量VOCs排放强度达到0.55~71.3g/m³。不同储罐排放特征差异大，炼化中间产物及污油储罐VOCs组成以烷烃为主，石化中间产物储罐VOCs以烯烃和芳香烃为主；C₃~C₇烷烃、C₃~C₄烯烃、苯、甲苯和丙酮等是首要污染物。中间储罐大呼吸损耗气具有较高大气光化学反应活性和臭氧生成潜势（OFP），OH自由基损失速率常数接近1.43×10⁴~2.37×10⁶s^-1，OFP达到2.84×10⁵~7.53×10⁷mg/m³，焦化污油反应活性与OFP较低，乙烯裂解重油储罐较高。大呼吸过程反应活性及臭氧生成潜势主要源于烷烃和烯烃组分，甲基戊烷、正己烷和甲基环己烷等C₆～C₇烷烃、C₃~C₅烯烃和二甲苯等是需要优先控制高活性物质。

关键词: 中间储罐, 石化企业, 挥发性有机物, 排放源, 臭氧生成潜势