Process hazards high temperature

Excessively high temperature, over and above that for which the equipment was designed, can cause structural failure and initiate a disaster. High temperatures can arise from loss of control of reactors and heaters and, externally, from open fires. In the design of processes where high temperatures are a hazard, protection against high temperatures is provided by... 

C hardness 9 Moh sp. gr. 3.98 thermal expansion (20-1000 C) 8.5 x 10- sp. heat 0.18 (20 °C), 0.22 (100 C). It occurs naturally, but impure, in S. Africa and elsewhere but is generally produced by extraction from bauxite followed by a firing process at high temperature. Corundum is used as an abrasive and as a refractory and electroceramic, e.g. in sparking plugs (see also alumina). COSHH. Control of Substances Hazardous to Health Regulations, 1988. See health and safety. 

Alkylation Hazards arise from the alkylating agents, e.g. dimethyl sulphate (suspected human carcinogen), hydrogen fluoride (highly toxic irritant gas) Thermal alkylation processes require higher temperatures and pressures, with associated problems... 

Chemical processing under "extreme conditions" of high temperatures and pressures requires more tliorough analysis and extra safeguards. As discussed in Chapter 7, e.xplosions at liigher initial temperatures and pressures are much more severe. Therefore, chemical processes under extreme conditions require specialized equipment design and fabrication. Otlier factors tlrat should be considered when evaluating a chemical process are rate and order of the reaction, stability of the reaction, and tlie healtli hazards of the raw materials used. 

The most important current technique for the thermal destmction of waste is incineration, where the energy required for destmction is provided by oxidation of the waste, sometimes supplemented with a fossil fuel. The major question about all thermal destmction techniques is whether products from the process—either traces of umeacted parent compound or compounds synthesized from the parent compound at high temperature— will pose a health hazard. 

Consider the case of the production of peroxy esters (e.g. tert-buty] peroxy 2-ethyl hexanoate), based on the reaction between the corresponding acid chloride and the hydroperoxide in the presence of NaOH or KOH. These are highly temperature sensitive and violently unstable, and solvent impurities are detrimental in their applications for polymerization. Batch operations to produce even 1000 tpa will be unsafe. A continuous reactor can overcome most of the problems and claims have been made for producing purer chemicals at lower capital and operation cost the use of solvent can be avoided. Continuous reactors can produce seven to ten times more material per unit volume than batch processes. Since the amount of hazardous product present in the unit at any given time is small, protective barrier walls may be unneccessary (Kohn, 1978). 

Examine all process parameters. Parameters (e.g., pressure, temperature, flow rate, level, pH) that are controlled or measured in a process are good indicators of possible process hazards. Process parameters should be examined for all modes of operation, independent of process chemicals, because some hazards exist that do not involve the chemicals. For example, if a process uses high-pressure steam, then both thermal energy and pressure-volume energy hazards exist even though steam is non-toxic, non-flammable, and non-reactive with most materials. 

CEP [Catalytic extraction processing] A process for destroying hazardous wastes by reaction with a molten metal at high temperature. Invented in 1989 by C. Nagel at the Massachusetts Institute of Technology and developed in the early 1990s by Molten Metals Technology, Waltham, MA. The company filed for bankruptcy in 1997. 

High temperature processes produce a slag, a non-leachable, non-hazardous material suitable for use as construction materials. most cases. 

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