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化学品失控反应危害与防范-失控聚合-丙烯酸及酯

The prevailing characteristic of Acrylic Acid is its high reactivity in the presence of free radicals. Free radicals can be generated by heat, light or irradiation and by activation of radical forming materials.

There are six main causes of unintended polymerization of Acrylic Acid:

Overheating (especially local overheating),

photo-initiation,

contamination,

corrosion,

inhibit or depletion, and

inhibit or deactivation (e.g. via dissolved oxygen depletion).

丙烯酸(AA)的醒目特征是其在自由基存在下的强烈反应特性。自由基可以通过热,光或辐射以及通过自由基形成物料的活化而产生。

丙烯酸非正常聚合的六个主要原因包括:

过热(特别是局部过热),

光触发,

沾染,

腐蚀,

阻聚剂原因或其损耗,和

阻聚剂原因或其失活(例如由于溶解氧耗竭)。

Several case histories of Acrylic Acid explosions were reported when procedures for proper handling or storage were disregarded. Depending on the conditions, the polymerization can proceed with moderate speed associated by a slow temperature increase, or it could be come violent under unfavorable conditions. Explosion hazards exist, if polymerizing material is enclosed in a poorly vented or unvented container. Pressure build-up may occur rapidly and can lead to the rupture of pipe lines, vessels and other containers. At a very high pressure build-up there is a serious risk of the reacting mass self-igniting.

Certain incidents with Acrylic Acid resulted ininjuries and even fatalities. Root cause analysis stipulated the implementation of temperature recording(s) to detect an early temperature increase which might indicate a beginning polymerization reaction with subsequent rupture of a tank or a vessel and a potential Boiling Liquid Expanding Vapor Explosion (BLEVE).

曾有报道过很多个关于丙烯酸爆炸的历史事例,都是其正确处置或储存的程序被忽视的情况下发生的。根据不同条件,聚合可以以缓慢的温度升高伴随温和的速率发生,也可在不利条件下变得剧烈。 如果聚合中的物料封闭在排气不良或未排气容器中,则存在爆炸危险。可能快速发生压力积累,并且可能导致管线,容器和其他容器破裂。当产生非常高的压力时,更存在反应物质自燃的严重风险。

若干丙烯酸事故导致了人员伤害甚至死亡。根本原因分析判定,实施温度记录以检测早期温度升高,可以指示造成储罐或容器破裂的聚合起点以及潜在的沸腾液体膨胀蒸气爆炸(BLEVE)

Acrylic Acid is commonly inhibited with 200ppm MeHQ (mono methyl ether of hydro quinone synonym: p-methoxyphenol), to ensure protection from an inadvertent polymerization. This protection is only effective at moderate ambient temperatures and for handling conditions described in the following chapters. The presence of oxygen is required for the inhibitor to function.

A head space containing sufficient air should always be maintained above the monomer to ensure inhibitor effectiveness.

ATTENTION:Acrylic Acid must never be handled under an inert atmosphere due to potential oxygen depletion.

丙烯酸通常用200ppm MeHQ(氢醌单甲醚、对甲氧基苯酚)作为阻聚剂,以确保防止无意的聚合。此保障措施仅在中等环境温度下和在下列描述的处理条件下有效。阻聚剂起作用还需要氧的存在。

在单体上方应始终保持含有足够空气的空间,以确保阻聚剂的有效性。

注意:由于含氧耗尽的潜在风险,丙烯酸决不能在惰性气氛下处置。

 

Overheating

Commercially available grades of Acrylic Acid have a shelf life of 1 year if properly handled. Shelf life is reduced exponentially with increasing temperature.

The recommended storage temperature of Acrylic Acid is 15°C-25°C. Testing and experience at these temperatures have shown no impact on safety, as long as shelf life is not exceeded.

The lower limit (15°C) is intended to provide a reasonable buffer from the freezing point (13°C). Low temperature storage also reduces Diacrylic Acid formation, also reducing the Acrylic Acid concentration (active substance). The upper limit (25°C) has been identified for safe Acrylic Acid storage to guarantee the aforesaid shelf life.

商用等级丙烯酸正确处置条件下保质期为1年。该保质期随着温度升高而呈指数缩减。

丙烯酸推荐储存温度为15-25℃。只要不超过保质期,测试和以往经验显示该温度范围对安全性不产生影响。

其下限(15)意在凝点(13)上增加合理缓冲。储存温度低也减少了丙烯酸二聚体的形成,避免丙烯酸的浓度降低(减少活性物质)。其上限(25)已被认定适于丙烯酸的安全储存,可确保前述保质期。


Overheating- especially local overheating of Acrylic Acid that may not be detected by temperature sensors – must be avoided. This may occur if:

Heat tracing is not applied properly,

Pumps are circulating without temperature monitoring of the circulated product,

Steam being applied to pipe surfaces accidentally or intentionally etc.

必须避免过热,尤其是温度传感器无法检测到的丙烯酸的局部过热。此类过热可能发生于:

伴热未正确使用,

泵在没有循环物料温度监测的情况下循环,

无意或有意地对管道表面施加蒸汽


Overheating becomes especially critical if inhibitor and dissolved oxygen are not present at saturation levels in the product. Therefore the recommendation is to limit the heating medium temperature to 35°C whilst a range of up to 45°C may be safe if proper inhibitor levels are maintained by thoroughly mixing the product or by other means.

如果阻聚剂和溶解氧未达到产品中应有的饱和度,则过热变得尤为突出。因此,建议将介质加热温度限制在35℃;当然,如果通过产品充分混合或通过其他方式保持适当的阻聚剂水平,则上达到45℃的温度范围也可能是安全的。

 

ATTENTION

Product temperatures of 30°C and higher can be hazardous and must be avoided during warming/heating and especially during thawing operations. The temperature of the heating medium not to exceed 35°C for safety reasons. Never use steam or steam condensate as direct heat transfer medium!

产品温度达到30℃或更高,可能产生危险;在温热/加热过程中,特别是在解冻操作过程中必须加以避免。出于安全原因,加热介质的温度不宜超过35℃。切勿使用蒸汽或蒸汽凝液作为直接传热介质!

 

Photo-Initiation by UV or X-Ray Radiation 紫外或X射线辐射所致光触发

Acrylic Acid can polymerize as a result of photo-initiation. Where sight glasses or other transparent sections are needed for visual observation in Acrylic Acid service, they should have covers to exclude light between observations. All containers such as IBC, drums, and bottles etc., used for storing Acrylic Acid should be kept from direct UV radiation.

丙烯酸可以由光引发而聚合。 如果在丙烯酸操作中需要视镜或其他透明部分进行目视观察,则需加盖以排除观察间歇的光照。用于储存丙烯酸的各种容器,如IBC,圆桶和瓶子等,应避免直接紫外线辐射。

ATTENTION

Never expose Acrylic Acid to direct sun or UV or X-ray radiation.

切勿将丙烯酸暴露于阳光直射或紫外线或X射线辐射。

Good house keeping must be exercised to avoid contamination of Acrylic Acid. Many compounds can promote polymerization, such as:

Peroxides and compounds which form peroxides and free radicals, including aldehydes, ethers, amines, azides, and NitricAcid

必须实施良好的洁净管理以避免丙烯酸的污染。许多化合物可以促进聚合,如:

过氧化物和形成过氧化物和自由基的化合物,包括醛,醚,胺,叠氮化物和硝酸

Catalytic traces of mineral Acids or strong bases enhance dimer formation. Accidental addition of mineral Acids or strong bases to Acrylic Acid will catalyze an exothermal oligomerization with potentially subsequent polymerization and is, therefore, a safety concern.

矿物酸或强碱的催化性痕量能增强二聚体形成。无意地将无机酸或强碱添加到丙烯酸将催化放热低聚,伴随潜在的后续聚合,因而产生安全隐患。

Care must be exercised to avoid contamination of monomer by polymerizing Acrylic Acid. Such polymer "seeds" could be generated in localized or hot stagnant areas, such as dead-headed pumps, and heated transfer lines. Polymer that has formed due to a contamination may cause further polymerization.

The formed polymer (Polyacrylic Acid) is insoluble in the monomer. It can be easily detected and filtered.

必须注意避免丙烯酸聚合物对其单体的污染。这种聚合物“种子”可以在局部或热滞留区域中产生,例如憋泵和热传导管线。由于污染而形成的聚合物可能引起进一步的聚合。

形成的聚合物(聚丙烯酸)不溶于单体。但可以很容易检测和滤出。


ATTENTION

Dedicated lines and unloading equipment, including hoses, pumps, transfer lines etc., are the best way to avoid cross contamination with incompatible materials.

专用管线和卸载设备,包括软管,泵,输送管线等,是避免不相容材料交叉污染的最佳方法。

Corrosion

Metal ions can initiate polymerization. Acrylic Acid, especially in the presence of water, will easily corrode carbon steel and similar metals. Corrosion and subsequent polymerization initiated by metal ions can not only be caused by improper material but also by accidental introduction of incompatible metals into the system such as gaskets, maintenance tools, carbon steel bolts and nuts

金属离子可以引发聚合。丙烯酸,特别是在含水条件下,容易腐蚀碳钢和类似的金属。由金属离子引发的腐蚀和随后的聚合不仅可能由不适当的材料引起,而且还可能由于不相容的金属偶然引入系统中而引起,例如垫圈,维护工具,碳钢螺栓和螺母。

 

ATTENTION

Inspect the compatibility of all construction materials with Acrylic Acid. Avoid accidental corrosion in any case.

检查所有构件材料与丙烯酸的相容性。避免任何情况下的意外腐蚀。

 

Inhibitors (stabilizers) are depleted with time. Elevated temperatures will accelerate this process. Observe the recommended storage time and temperature to prevent depletion of the inhibitor as well as premature depletion of oxygen. Elevated temperatures can accelerate inhibitor depletion.

阻聚剂可随时间而损耗。温度升高可加速这个过程。应遵守推荐的储存时间和温度,以防止阻聚剂耗尽或氧气过早耗尽。温度升高可加速阻聚剂损耗。

ATTENTION

Observe shelf life and proper storage conditions of Acrylic Acid to avoid inhibitor depletion.

应遵守丙烯酸保质期和适当的储存条件,以避免阻聚剂耗尽。

 

Dissolved oxygen is essential for the effective functioning of inhibitors (MeHQ). The inhibitor-oxygen adduct acts (is acting) as initial, and very efficient, radical scavenger. Once the dissolved oxygen is consumed, polymerization will start. Therefore, never handle Acrylic Acid under pure nitrogen or any other oxygen-free atmosphere. An air-nitrogen mixture may be used which also avoids flammability concerns.

An air-nitrogen mixing station can be designed to yield a gas containing a minimum of 5 Vol.-% oxygen. Equipment measurement tolerances must be carefully considered to ensure the operating range remains comfortably between the LOC and the minimum recommended oxygen concentration (5%). For example if analysis of the proposed mixing station design shows that the tolerance is 1,5%, then the set point of the system must be 6,5% in order to ensure that the oxygen concentration is always above 5Vol.-%. The design of the mixing station should be reviewed with local safety personnel to ensure that both criteria are met: sufficient oxygens upply during regular and emergency cases and protection from flammability.

Oxygen is consumed slowly during storage. Therefore the level of dissolved oxygen should be periodically replenished with air (or an oxygen / nitrogen gas mixture, “lean air mixture”). Sufficient oxygen levels in drums or IBCs can be achieved by agitating and moving them from time to time. The consumption rate of oxygen in water diluted Acrylic Acid is much higher than in pure Acrylic Acid. It is recommended to replenish oxygen levels more frequently when water is present.

溶解氧对于阻聚剂(MeHQ)发挥效用极为必要。阻聚剂 - 氧加合物共同作用,成为基本而又高效的自由基清除剂。一旦溶解的氧耗尽,聚合就会发生。因此,切勿在纯氮或任何其它无氧气氛下处置丙烯酸。可以使用空气 - 氮气混合物,其也避免了可燃性问题。

可以设计一种空气 - 氮气混合站以产生含有最少5vol .-%氧气的气体。 必须仔细考虑设备测量公差,以确保操作范围在LOC和最低推荐氧浓度(5%)之间保持平衡。 例如,如果对所提出的混合站设计的分析显示公差为1.5%,则系统的设定点必须为6.5%,以确保氧浓度总是高于5Vol .-%。 混合站的设计应与当地安全人员一起审查,以确保满足两个标准:在正常和紧急情况下充足的氧气,并防止可燃性。

储存期间氧气会被缓慢消耗。 因此,溶解氧的水平应该周期性地用空气(或氧/氮气混合物,“贫空气混合物”)补充。 圆桶或IBC中充足的氧水平可以通过搅拌和不时地移动它们来实现。水稀释的丙烯酸中的氧气消耗率比纯丙烯酸高得多。当水存在时,建议更频繁地补充氧水平。

 

Freezing

Water free Acrylic Acid freezes at 13°C. During the crystallization process the inhibitor is separated and concentrated in the liquid phase. Dissolved oxygen concentrations are also reduced. Appropriate engineering design and operating measures must be taken to avoid freezing of Acrylic Acid (heat tracing, insulation, emptying stagnant pipelines etc.).

无水丙烯酸在13 凝结。结晶过程中,阻聚剂析出并在液相中浓缩。溶解氧浓度也降低。 必须采取适当的工程设计和操作措施,以避免丙烯酸的冻结(伴热,隔热,排空滞留管道等)。

ATTENTION

Never remove liquid from partially frozen or partially thawed Acrylic Acid! This will result in insufficient stabilization/inhibition.

切勿从部分凝结或部分解凝的丙烯酸中移出液体! 这将导致其稳定性/阻聚性不足。

 

Acrylic Acid / Water Mixture

Water is sometimes added to Acrylic Acid (Acrylic Acid concentration 80-90wt.-%) in order to lower the freezing point and to increase the flash point. This procedure has to be done following best practices since it may otherwise affect the safe handling aspects of these mixtures:

Tap water must not be used to dilute Acrylic Acid. De-ionized water should be used instead. Due to a high content of trace metals compared to de-ionized water this may cause inadvertent polymerization.

Adding water to Acrylic Acid results in a decrease of the shelf life. A water concentration of 20% reduces the shelf life to about 3 months. Acrylic Acid-water solutions should be consumed shortly after preparation or receipt.

Water lowers the solubility of oxygen which is needed for inhibition / stabilization. It is recommended that storage occurs with a minimum of 21Vol.-% of oxygen in order to maintain the dissolved oxygen concentration in diluted Acrylic Acid at a safe level.

有时向丙烯酸(丙烯酸浓度80-90重量%)中加入水,以降低凝点、提高闪点。该程序必须按照最佳做法进行,否则可能会影响这类混合物的安全处置:

自来水不得用于稀释丙烯酸。应使用去离子水。与去离子水相比,自来水中痕量金属含量高,无意间可能引发聚合。

向丙烯酸中加水会导致保质期降低。含水量20%的,保质期降低至约3个月。丙烯酸 - 水溶液应在制备或接收后尽快使用掉。

水会降低阻聚/稳定所需的氧的溶解度。储存时建议至少含21Vol .-%的氧气,以便将稀释的丙烯酸中的溶解氧浓度保持在安全水平。

The stability of diluted Acrylic Acid when exposed to high temperatures (e.g. non-insulated storage tanks being exposed to strong sun radiation or fire) is further decreased as compared to stability of non-diluted Acrylic Acid when exposed to such temperatures.

The formation rate of Di acrylic Acid (2-Carboxyethylacrylate) increases with increasing water levels.

Corrosion rates to lower grade stainless steel like DIN1.4541 are much higher compared to DIN1.4571. The recommendation therefore is to use 316L or DIN1.4571 for storage of diluted Acrylic Acid.

Pipelines containing Acrylic Acid / Water Mixtures need to be emptied or purged immediately after use due to the increased oxygen depletion.

Water concentrations above 20% are not recommended due to the fact that the maximum achievable oxygen concentration is too low and is likely to cause a premature polymerization.

Therefore dilution of Acrylic Acid with additional water cannot be recommended as an emergency practice.

与未稀释的丙烯酸接触相似温度时的稳定性相比,稀释的丙烯酸接触高温(例如,非隔热储罐暴露于烈日辐照或明火)时的稳定性进一步降低。

丙烯酸二聚体(2-羧乙基丙烯酸酯)的形成速率随着含水量的增加而增加。

对于低等级不锈钢(如DIN1.4541)的腐蚀速率比DIN1.4571高得多。因此,建议使用316LDIN1.4571储存稀释的丙烯酸。

含有丙烯酸/水混合物的管道需要在使用后立即清空或吹扫,因为如有残液,其氧耗会增加。

不推荐使用高于20%的水浓度,因为最大可达到的氧浓度太低从而可能引起提前聚合。

因此,不能建议使用额外的水稀释丙烯酸作为应急措施。

Product temperatures above30°C should be reported immediately for further investigation and support. And if the temperature is confirmed to exceed 30°C the vessel should be isolated.

Do not approach a tank whose contents have reached or exceeded 50°C.

All personnel should be evacuated from a tank whose contents have reached or exceeded 60°C.

产品温度高于30℃时应立即报告以深入调查并寻求帮助。如果确认温度超过30℃,则应将容器隔离。

不要接近内容物已达到或超过50℃的储罐。

所有人员应从内容物已达到或超过60℃的储罐附近撤离。

 

丙烯酸衍生物具有与丙烯酸类似的特性,需逐个查询并采取相应的危害控制措施。

这些衍生物包括:

Acrylate Esters 丙烯酸酯

       Methyl Acrylate (MA) 丙烯酸甲酯

       Ethyl Acrylate (EA) 丙烯酸乙酯

       N Butyl Acrylate丙烯酸丁酯

       2-Ethylhexyl Acrylate丙烯酸乙基己酯

Methacrylic acid (MAA) 甲基丙烯酸

Methacrylate Esters 甲基丙烯酸酯

       Methyl Methacrylate (MMA) 甲基丙烯酸甲酯

       Ethyl Methacrylate 甲基丙烯酸乙酯

       N Butyl Methacrylate 甲基丙烯酸丁酯

       ISO Butyl Methacrylate 甲基丙烯酸异丁酯

       2-Ethylhexyl Methacrylate 甲基丙烯酸乙基己酯




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