年6月30日 天津市安全生产委员会发布了《市安委会办公室关于吸取事故教训开展环保治理设施专项安全检查的通知》（津安办〔2017〕32号）（以下简称通知），通知中提到：“对采用'低温等离子'等可能产生点火能的工艺或设备设施处理易燃易爆挥发性有机物的，或采用湿法除尘处理铝、镁等金属涉爆粉尘的环保设施，要立即停用，并全面进行安全风险评估，严防类似事故再次发生”。 On June 30, 2017 , Tianjin Municipal Work Safety Committee issued the Notice of the Office of the Municipal Safety Commission on Learning from Accidents and Conducting Special Safety Inspections of Environmental Protection and Governance Facilities (Jinan Office  No. 32) (hereinafter referred to as the notice). It was mentioned: "For environmental protection facilities that use processes or equipment that may generate ignition energy such as 'low-temperature plasma' to treat flammable and explosive volatile organic compounds, or wet dust removal to deal with explosive dusts of metals such as aluminum and magnesium, Immediately deactivate it and conduct a comprehensive safety risk assessment to prevent similar incidents from happening again. " After the notice was issued, it aroused widespread concern and controversy in the industry on low temperature plasma technology for the treatment of organic waste gas and malodorous gas treatment engineering applications.
低 温等离子体技术在VOCs治理工程中应用安全性研讨会”在北京银龙苑宾馆顺利召开。 On November 22, 2017, the " Seminar on the Safety of the Application of Low Temperature Plasma Technology in VOCs Treatment Engineering " sponsored by the China Environmental Protection Industry Association and undertaken by the China Environmental Protection Industry Association's Exhaust Gas Purification Committee (referred to as the Exhaust Gas Purification Committee) was held in Beijing Yinlongyuan Hotel was successfully held. The meeting discussed the contents of the notice of Tianjin Work Safety Committee and the engineering practice and safety issues of low temperature plasma technology in recent years. At present, low-temperature plasma technology is widely used in VOCs treatment projects. Among them, plasma treatment of VOCs waste gas technology is included in the Ministry of Environmental Protection's "Volatile Organic Compounds (VOCs) Pollution Prevention Technology Policy" (Ministry of Environmental Protection Announcement 2013 No. 31), "Dual Medium Barrier Discharge Low Temperature Plasma Odor Gas Treatment Technology" Selected by the Ministry of Environmental Protection "2016 National Advanced Pollution Prevention Technology Catalog (VOCs Prevention and Control Field)" (Ministry of Environmental Protection Announcement 2016 No. 75). The Tianjin Work Safety Committee's notice only addresses specific safety incidents and is very institutionalized, and there is no evidence that such safety incidents are directly related to the use of low-temperature plasma technology. Engineering practice shows that low temperature plasma technology has its suitable application range and plays an important role in treating VOCs exhaust gas and improving air quality. After discussing the application scope, use conditions, and safety of low-temperature plasma exhaust gas treatment facilities, the following suggestions were formed:
(I) Application scope of low temperature plasma technology
(1) The low-temperature plasma technology uses high-activity particles generated by gas discharge to collide with pollutant molecules to dissociate and oxidize them, thereby achieving the purpose of purifying exhaust gas. In recent years, the low-temperature plasma technology has been widely used in the treatment of low-concentration VOCs-containing exhaust gas and malodorous odor gas. Engineering practice shows that this technology has a good purification effect on low-concentration VOCs-containing exhaust gas (generally lower than 300mg / m3) and offensive odor gas.
的净化效果存在差异，在具体的工艺设计时应根据各种工况下废气的成分和浓度，确定低温等离子体净化技术的适应性。 (2) Due to the different energy required for dissociation and oxidation of different types of compounds, the low-temperature plasma technology has different purification effects for different types of organics and odorous pollutants . The specific process design should be based on various operating conditions. The composition and concentration of the exhaust gas were determined to determine the adaptability of the low-temperature plasma purification technology.
时，低温等离子体一般不宜作为独立的处理单元应用，需与其他处理单元联合使用，通常作为二级净化单元方能取得较好的处理效果。 (3) When the concentration of organic waste gas is high , low temperature plasma is generally not suitable as an independent processing unit. It must be used in conjunction with other processing units. Generally, it can be used as a secondary purification unit to obtain better treatment results.
，因处理周边可能存在阵发性的有机废气，使用时应审慎评估。 (4) In the occasions with high requirements for explosion-proof grades such as petrochemicals and chemical industries, due to the possibility of the occurrence of paroxysmal organic waste gas in the surroundings, it should be carefully evaluated during use.
(II) Safety analysis of low-temperature plasma purification equipment
At present, there are many companies engaged in the purification of low-temperature plasma VOCs in the market, and their professional levels are uneven. Some companies do not have the design capabilities of low-temperature plasma equipment, and the process design, engineering implementation and service guarantee capabilities are lacking. Some users also use There are problems such as irregular operation and inadequate operation and maintenance. Engineering applications have certain security risks.
The safety risks of low-temperature plasma purification equipment in use mainly include the following aspects:
，达到了被净化物质（或混合物）的爆炸极限值，电极放电时造成设备爆炸。 (1) The concentration of organic matter accumulated in the exhaust gas itself or the processing system is high , reaching the explosive limit value of the purified substance (or mixture), and the device explodes when the electrode is discharged.
，废气中的油雾或漆雾等颗粒物进入低温等离子体净化设备，沉积在电极或器壁上，积累到一定程度后会引起设备着火。 (2) The exhaust gas pretreatment is not in place , and the oil mist or paint mist in the exhaust gas enters the low-temperature plasma purification equipment and is deposited on the electrode or the wall, which will cause the equipment to catch fire when accumulated to a certain degree.
(3) Certain compounds polymerize in a low-temperature plasma environment, deposit coke on the electrode or vessel wall, and accumulate to a certain extent, which may also cause the equipment to catch fire.
(Three) suggestions on the safety of low-temperature plasma technology
(1) Low-temperature plasma technology is suitable for the treatment of low-concentration VOCs exhaust gas (generally lower than 300mg / m3), and the exhaust gas concentration should be far below the lower explosion limit to ensure that there is no explosion danger.
(2) For exhaust gas containing particulate matter such as oil mist or paint mist, appropriate pretreatment processes such as high-efficiency filtration should be configured to ensure the safety of low-temperature plasma processing equipment.
(3) Before starting the low-temperature plasma unit, the fan purge processing system needs to be started to prevent the discharge sparks from igniting the accumulated high-concentration organic matter.
(4) The deposits on the electrodes and the wall should be cleaned and maintained in a timely manner.
(5) Strengthen the safety measures such as monitoring, pre-alarming, and emergency handling in all aspects of product design, manufacturing, operation and maintenance from the entire process of low-temperature plasma product production and use.
In view of the current problems of low-temperature plasma technology in the treatment of exhaust gases, it is recommended that enterprises should formulate corporate standards and make self-declarations based on their product characteristics, improve the quality of products and projects, and prevent risks from safety risks, and accept social supervision.