Mitigation chemical reaction

The purpose of this publication is to contribute to a continued reduction in the number and severity of incidents involving uncontrolled chemical reactions in the workplace. The obj ective of this publication is to convey the essentials of managing chemical reactivity hazards—those elements that are necessary, but not always sufficient, to avoid or mitigate chemical reactivity incidents. Implementing these elements should result in a management system that will, on an ongoing basis ... 

McIntosh, R.D. and Nolan, P.F. (2001) Review of the selection and design of mitigation systems for runaway chemical reactions. Journal of Loss Prevention in the Process Industries, 14, 27-42. 

The main objective of a fluid curtain is to help mitigate explosions by absorbing energy as droplets break up and by creating an increased total surface area to reduce potential flammable and toxic hazard zones by dilution with air or by chemical reaction with the water or reactive materials contained in the curtain. 

The reactor and the hydrogen production system are connected by the helium gas loop. A chemical reactor causes the temperature fluctuation of the secondary helium gas by the fluctuation of the chemical reaction that occurs at the normal start-up and the shutdown operation as well as malfunction or accident of the hydrogen production system. If the temperature fluctuation is transferred to the reactor, the reactor will be stopped. Therefore, the control technology should be developed to mitigate the temperature fluctuation within an allowable range to keep reactor operation, using a thermal absorber. JAEA proposed to use a steam generator (SG) as the thermal absorber that is installed downstream the chemical reactor in the secondary helium gas loop. 

Control of airborne effluent such as gases, vapors and particulate matter in smoke is very difficult in a chemical warehouse environment. Design criteria currently does not exist for systems to mitigate airborne releases resulting from fires, decomposition or incompatible chemical reactions. Therefore, the emphasis should be on preventing these incidents from occurring. 

Many CVD processes are affected strongly by contaminants in the vapor. The contaminants originate from the reactants themselves and from various chemical reactions between the gases and the materials in the gas dispensing system (in the tubes, evaporators, sublimators, e. g., reaction location 3 in Fig. 1-1) and from ambient atmosphere leakage into the reactor system. Contamination levels may be mitigated by ... 

Formation of black powder (BP) is one of the reasons of internal corrosion in pipelines. BP resnlts from chemical reactions between components of the transported gas (HjS and COj) and primarily the iron (Fe) portion of ferrous pipe alloys. In some cases, microbial action exacerbates the ongoing chemical process. The presence of water is key to supporting biological and certain chemical corrosion phenomena leading to BP. The formation of BP in pipelines may be mitigated by the following ... 

This iteration method is fundamentally different from all other methods discussed in Chapter 7. It basically produces iterated solutions that are valid over the whole domain of interest. As the iteration increases, the iterated solution is (hc fully) getting closer to the exact solution. This method is known as the Picard method. The fundamental disadvantage of this technique, which mitigates its usefiilness, is that the iterated solutions must be found analytically, so that they can be applied to subsequent iteration steps (which involves the evaluation of an integral), (a) Show that the modeling of a second order chemical reaction in a fixed bed reactor would give rise to the following differential... 

This tends to cause unrealistic change in the progress of chemical reactions. The modified Curl s model (Janicka, Kolbe and Kollmann, 1979) is one possible method to mitigate this tendency. In this method, the scalar exchange of a pair of particles (wi and W2) is calculated from a uniform random number C between 0 and 1 ... 

The tendency towards chemical reactions involving water and cosolvents on the hot desiccator bed surface is mitigated by the atmosphere within the bed being nearly free of oxygen as pure nitrogen... 

Surfactant templating chemistry can be extended to many nonsilicate compositions after modifications to the synthesis route. These materials are less structurally stable than the mesoporous silicates, which is attributed to the thinness of the amorphous pore walls ( 1 to 2 nm). Stucky and coworkers [85,86] showed that this problem could be mitigated by preparing the materials with thicker walls. To prepare mesoporous WO3, they dissolved a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer and WCle salt in ethanol, and dried the resulting solution in open air. The tungsten salt reacted with moisture to undergo hydrolysis and condensation reactions. These chemical reactions caused the eventual formation of amorphous WO3 around triblock copolymer micelle-like domains, and after calcination at 400 C, a mesoporous WO3 with thick, nanocrystalline walls ( 5 nm) and surface area of 125 m /g was formed. 

A number of factors must be considered in deep-well disposal. Wastes are injected into a region of elevated temperature and pressure, which may cause chemical reactions to occur involving the waste constituents and the mineral strata. Oils, solids, and gases in the liquid wastes can cause problems such as clogging. Corrosion may be severe. Microorganisms may have some effects. Most problems from these causes ean be mitigated by proper waste pretreatment. 

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