Incineration corrosion

In addition to the most conunon contaminants previously mentioned, pollutants such as hydrogen chloride, chlorine, hydrogen fluoride, and hydrogen bromide are produced as combustion products from the burning of chemical waste. When organophosphorous compounds are incinerated, corrosive phosphorous compounds are produced. Chlorides are also a product of municipal waste incinerators. 

Y. Kawahara, N. Orita, M. Nakamura, S. Ayukawa, and T. Hosoda, Laboratory Corrosion Tests for Simulating Fireside Wastage of Superheater Materials in Waste Incinerators, Corrosion/99, Paper No. 89 (San Antonio, TX), NACE, 1999... 

Y. Fukuda, Y. Kawahara, and T. Hosoda, Application of High Velocity Flame Sprayings for Superheater Tubes in Waste Incinerators, Corrosion/2000, Paper No. 264 (Orlando, FL), NACE, 2000... 

The level of natural versus man-made emissions to the environment are of a similar magnitude. SoH erosion is the major contributor of natural emissions with zinc mining, zinc production facHities, iron and steel production, corrosion of galvanized stmctures, coal and fuel combustion, waste disposal and incineration, and the use of zinc fertilizers and pesticides being the principal anthropogenic contributors. 

In water-wall incinerators. The internal walls of the combustion chamber are lined with boiler tubes that are arranged vertically and welded together in continuous sections. When water walls are employed in place of refrac toiy materials, they are not only useful for the recovery of steam but also extremely effective in controlling furnace temperature without introducing excess air however, they are subject to corrosion by the hydrochloric acid produced from the burning of some plastic compounds and the molten ash containing salts (chlorides and sulfates) that attach to the tubes. 

As many emissions involve chlorinated compounds, corrosion is a major problem in many control methods. The corrosion of columns and surface condensers can be prevented or reduced by the correct material selection. However, corrosion remains a constant threat to the interior of incinerators. Additional pollution control equipment such as scrubbers may also be required to remove acidic compounds from treated gases before discharging into the atmosphere. 

Table 7.33 Corrosion rack tests of nickel- versus iron-base alloys used in waste incineration...

Dunn and Tomkins (1975) discuss the design and operation of incinerators for process wastes. They give particular attention to the need to comply with the current clean-air legislation, and the problem of corrosion and erosion of refractories and heat-exchange... 

The wastewater generated in the membrane cell and other process wastewaters in the cell are generally treated by neutralization.28 Other pollutants similar to those in mercury and diaphragm cells are treated in the same process stated above. Ion exchange and xanthate precipitation methods can be applied in this process to remove the metal pollutants, while incineration can be applied to eliminate some of the hydrocarbons. The use of modified diaphragms that resist corrosion and degradation will help in reducing the amount of lead, asbestos, and chlorinated hydrocarbon in the wastewater stream from the chlor-alkali industry.28... 

Specific types of relief devices are chosen for specific applications, such as for liquids, gases, liquids and gases, solids, and corrosive materials they may be vented to the atmosphere or vented to containment systems (scrubber, flare, condenser, incinerator, and the like). In engineering... 

In most hydrocarbon operations excess gas and vapors have to disposed of safety, quickly without environmental impact. Where the gas or vapor cannot be converted into useful energy they are routed to a remote point for safe incineration, called flaring. Flares are the most economical and customary means of disposing of excess light hydrocarbon gases in the petroleum and chemical industries. The primary function of a flare is to convert flammable, toxic or corrosive vapors to environmentally acceptable gases for release into the atmosphere. Both elevated or ground flares can be used. 

A reaction commonly developed in the discovery lab is removing a Boc group from an amine using trifluoroacetic acid (TEA). Because TEA is highly corrosive, difficult to contain and recover (bp 72°C), and poses incineration problems due to the generation of HE, alternative conditions are usually explored for scale-up. Strong acids used instead of TEA include HCl, H2SO4, methanesulfonic acid, and toluenesulfonic acid... 

Although the role of crystalline phases in the leachability of HT materials is unclear and must be examined from case to case, the identified silicates and oxides are overall more resistant to corrosion than silicate glass and residues of incineration (Scholze 1991). Thus, a clear assessment of the durability of HT materials as a function of crystalline components must take into account the combined effects of their enrichment or depletion in trace metals, their individual leachability, the increase (but sometimes decrease) in overall reactivity due to local heterogeneities and increased Sspec (Jacquet-Francillon et al. 1982 Bickford Jantzen 1984 Jantzen Plodinec 1984 Scholze 1991 Adams 1992 Sproull et al. 1994 Sterpenich 1998). 

The chemistry of chlorine, as well as other halogens, plays an important role in combustion and in a number of industrial processes. The reactions of chorine and chlorinated hydrocarbons are important in incineration of hazardous chemical wastes, which frequently contain these compounds. Also fuels such as biomass may contain significant amounts of chlorine. In biomass combustion, chlorine interacts with sulfur and alkali metals, a chemistry that has considerable implications for aerosol formation, deposit formation, and corrosion but is rather poorly understood. 

If possible, locate combustible cooling towers at a safe distance from ignition sources such as incinerators or stacks. Towers that must be near such hazards should be constructed entirely of noncombustible material, or at least the shell should be made from noncombustible materials. Fan openings should be protected with-i-in corrosion-proof wire mesh. 

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