Runaway reactions report

EPA, How to Prevent Runaway Reactions, Report 550-F99-004 (August 1999). Available at www.epa. gov/ceppo/. 

There are two philosophies regarding how to best slow a runaway reaction. One view holds that simple water deluge is the best method as it provides immediate cooling and dilution. The anti position is that the batch should be deluged and neutralized simultaneously. Kumpinsky reports that minimum self-heat rates occur between pH 4 and 7 [78]. Since neutralization involves production of additional heat, because the pH of a runaway batch is rarely known, and since the phenolic reactions are catalyzed by acid, base, and salt it seems likely that simple deluge is the surest method. 

For the third edition, I added sections or chapters on heat exchangers, furnaces, inherently safer design, and runaway reactions, and extended many other chapters. Although I have read many accident reports since the first edition appeared, most have merely reinforced the messages of the book, and I added only those incidents that tell us something new. 

The most recent major expln in a US TNT plant occurred in May 1974 at the Radford Army Ammunition Plant. The accident completely destroyed one of the three continuous nitration lines at the plant. According to the AMC News, Sept 1974, the investigation board reported that an operator inadvertently introduced a 5 to 6-foot rubber hose to clean out unwanted material that had collected in a transfer line leading to the nitrator, when the hose was pulled from his hands into the nitrator. This resulted in a rapid temp rise and subsequent explosion. The hose was commonly used in this manner . The material causing the blockage in the transfer line was believed to be an oxidation product of TNT, 2,2 -dicarboxy-3,3, 5,5,-tetra-nitroazoxybenzene, also referred to as White Compound. The introduction of the rubber hose caused a rapid, exothermic oxidation reaction between the hose material and the mixed acid present. The heat generated by this reaction caused a local acceleration of the normal nitration/oxidation reactions which occur in the nitrator until a critical temp was reached, at which point rapid oxidation of DNT/TNT proceeded as a runaway reaction, igniting the material present in the vessel. 

However, one must remember that the accumulation of phenylhydroxy-lamines presents a serious danger because these compounds disproportionate with the liberation of much heat and may cause a runaway reaction, that is, an explosion (Fig. 2.33). This becomes especially dangerous if the reaction temperature gets close to 250°C, the autodecomposition temperature of phenylhy-droxylamine. Some of these accidents have been reported.277... 

Other news coverage or investigative reports do acknowledge the fact that the presence of water in the system lead to runaway reactions. However, several other reports were not able to identify the precise route for the entry of water. 

The Wall Street Journal reported that several weeks before the Bhopal disaster, Union Carbide changed procedures at its Institute West VA plant, on which the Bhopal plant design was based, to prevent a similar incident. Rep. Henry Waxman (D. CA.) disclosed that a Union Carbide safety team in September had warned of a potential runaway reaction of methyl isocyanate at Institute and the EPA had reported that there were 28 small leaks of the chemical in 1980 at the facility (Winslow, 1985). 

In an attempt to achieve solvent free preparation of ionic liquids, others have reported an improved approach whereby the reaction temperature was moderated by placement of the reaction vessel in a water bath. For example, Chan et al. [108] attempted to moderate the heat of the quatemisation reaction and thereby large scale preparation of imidazolium and pyridinium-based ionic liquids. Water moderation was successfully applied to avoid runaway reactions in the large-scale preparation of a number of ionic liquid precursors under solventless conditions using microwave irradiation ... 

It can react violently with strong reducing and oxidizing agents. Runaway reactions have been reported for HNO MnO J Cr,07, Brj, Cl, gas, NaH, NaBHi and alkyl Al compounds, even though DMF is a good solvent for many of the above. The reasons for this are not yet understood. 

When the column chemicals are thermally unstable and decompose exothermically, an excessive bottom temperature can cause a "runaway reaction and sometimes lead to an explosion. Some experiences with such explosions have been reported in distillation of peroxide, nitro, hydrocarbon oxide, and acetylenic compounds (16o, 96, 97, 209a, 275). 

Nitration, like halogenations, occurs preferentially at the 4- or 5 position in A/ -unsubstituted and A/-substituted imidazoles. As with all nitrations, poly-nitration can occur, and there is the potential for subsequent thermal hazards or runaway reactions. Despite its lack of reactivity, polynitration products have been reported. 

CSB Report, Investigation Report, Pesticide Chemical Runaway Reaction Pressure Vessel Explosion, August 28, 2008. 

Nolan, P.F., 1983, A Report for the Health and Safety Executive on the Case Histories of Runaway Reactions (HSE, UK). This report drew its material from HSE files, the IChemE Loss Prevention Bulletin and Case Histories of Accidents in the Chemical Industry by the Manufacturing Chemists Association, Volumes 1-4. 

For process equipment, designers need to specify necessary safety features and the tests for meeting requirements. For process equipment, there should be fail-safe features. Fire protection, overpressure, excess heat, runaway reactions, dust control, exhaust ventilation, dangers of flammable liquids, leaks, sensing devices to report status are all examples of important safety features. Designers and purchasers need to consider access for setup, maintenance and cleaning. There may be a need for access by stairs, fixed ladders or platforms as part of large equipment. 

Numerous attempts have been made to quantify the probability of having TBP runaway reactions. However, these assessments are usually inconsistent with the historical record of TBP accidents (Usachev and Markov, 2003 LANL DOE Report, 1993). In fact, during this time period, six events have been reported (Barney and Cooper, 1994). 

U.S. EPA, Chemical safety case study How to prevent runaway reactions, EPA, Chemical Emergency Preparedness and Prevention Office, Report no. EPA 550-F99-004, 1999. 

Chemical Safety Board, CSB Investigation Report T2 Laboratories, Inc., Runaway Reaction, http //www.csb.g0v/assets/l/19/T2 Final Copy 9 17 09.pdf, (accessed Mar 2015). 

Si-H bonds add across olefins over platinum catalysts. This reaction (hydrosi-lation) is used in silicone polymer manufacture, when the silane is a hydrogen bearing oligo(alkylsiloxane). With some types of olefin there have been reports of runaways to explosion because of unexpectedly fast reaction. Dangerous substrates recorded are 2-allylphenols and ethenylsiloxanes. Very low levels of catalyst (ppm) and good cooling are recommended. 

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