Alkali corrosion

The effect of temperature on alkali corrosion is illustrated by data from this paper in Table 18.10. There are various glass compositions in service and it is important to ensure that the lining is appropriate for the particular... 

Chemical-resistant Highest chemical resistance of polyester group excellent acid resistance, fair in alkalies. Corrosion-resistant applications, such as pipe, tanks, ducts, fume stacks. 

Alkalis Corrosive in <0.01% solutions of NaOH and KOH. Alloys containing 4% Mg resist corrosion... 

For particle cleanup cyclones, impact separators, fabric and fiber filters, granular beds, and electrostatic percipitators for low-temperature gas cleaning have been widely used in the industry. However, for hot gas filtration with ceramic filters, the long-term durability, alkali corrosion, cleanability, thermal shock, and particulate penetration into filter media has been recognized as major concerns. Traditional bag filters are sensitive to high ten erature and hot particles, electrostatic percipitators have a relatively high cost of installation in smaller plants and multi-cyclone cleaners are not sufficiently efficient to meet the new purification demands. 

See also Alkalies Corrosives Gastrointestinal System Skin. 

The hot raw syngas at the gasifier outlet contains not only H2, CO, CH4, C02, sulfur, and nitrogen compounds, but also H20, alkali (potassium and sodium), and mercury. In order to prevent alkali corrosion of hot gas cleanup components and to avoid expensive materials and unreliable refractory-lined piping,200 201 it is necessary to reduce the temperature to less than 540 °C for complete condensation of the alkali vapor on particulates in the hot syngas. 

III. Predictions of Alkali Corrosion of Alumino-Silicate Refractories... 

Generally alkali corrosion of ceramics involves the salts or oxides of sodium and/or potassium. These alkalis are corrosive in the solid, liquid,... 

Although many different types of investigations in the area of alkali corrosion of refractories have been performed, there still appears to be doubt regarding the best method for testing. In addition, there are few comparative studies in the literature showing the differences in alkali corrosion of the different alumino-silica refractories. Studies concerning silicon carbide bricks exposed to alkalies are practically nonexistent. 

Flayden [52] conducted a controlled series of alkali corrosion tests of commercial refractories using the crucible cover technique illustrated in Fig. 13. This test involved placing a refractory sample over a crucible containing a premeasured amount of alkali carbonate and heating the assembly to 1350°C for 12 h. A furnace containing a load of test samples is... 

Properties Ductile shiny silver-white metal. D 7.31 (20C), mp 156C, bp 2075C, Mohs hardness 1.2. Softer than lead. Soluble in acids insoluble in alkalies. Corrosion-resistant at room temperature. Oxidizes readily at higher temperatures. 

Colourless liquid acetone-like odour. Explosive when pure usually used as a 60% solution in dimethyl phthalate. Strong oxidizing agent reacts violently with salts of heavy metals, acids and alkalis. Corrosive, produces liver and kidney damage. 

CALCIUM ALKYLAROMATIC SULFONATE (27176-87-0) CijHjoOjS Combustible liquid. Forms explosive mixture with air (flash point 395°F/202°C). Strong oxidizers may cause fire and explosions. Contact with strong acids forms highly toxic sulfur oxide fumes. Reacts with alkalis. Corrosive to metals. When heated to decomposition releases highly toxic sulfur oxide fumes. On small fires, use dry chemical powder (such as Purple-K-Powder), alcohol-resistant foam, or COj extinguishers. 

BENZENE SULFONIC ACID, DODECYL ESTER (27176-87-0) Forms explosive mixture with air (flash point 100°F/38°C). Strong oxidizers may cause fire and explosions. Reacts with alkalis. Corrosive to metals. 

Solid, dj 1.4812. mp 20. bp 0 167 bp, 122. Soly at 26-28 in wt % hexane, 0 methylcyclopentane, 0 benzene, 1.50 toluene, 0.38 o-chlorotoluene, 0.23 ethyl disulfide. 0.47. Thermally stable at moderately elevated temps. Not hydrolyzed by boiling water or hot aq alkali. Corrosive to iron, steel, brass, copper, lead. 

CHEMICAL PROPERTIES noncombustible incompatible with strong alkali corrosive to metals reacts with iron and rust to form toxic gases reacts vigorously with oxidizing materials susceptible to epoxidation... 

CHEMICAL PROPERTIES stable to heat reacts vigorously with strong acids and strong alkalis corrosive to iron and mild steel FP (>79.4°C, >175°F). 

Composite behavior has also been studied in oxide systems (e.g., oxide fiber-reinforced porous oxide matrix composites with no interfacial coatings). Oxide composites have the attractive features of oxidation resistance, alkali corrosion resistance, low dielectric constants, and potentially low cost. Because of these properties, oxide CMCs could be attractive for hot gas filters, exhaust components of aircraft engines, chemical processing equipment, and long-life, lower temperature components. 

Properties Colorless liq. or rhombic crystals, odorless sol. in water, alcohol misc. with many org. soivs. m.w. 97.99 dens. 1.70 (20/4 C) vapor pressure 0.0285 mm (20 C) m.p. 42.4 C b.p. 158 C starts to dec. above 200 C forming polyphosphoric acids Toxicology ACGIH TLV/TWA1 mg/m STEL 3 mg/m LD50 (oral, rat) 1530 mg/kg, (skin, rabbit) 2740 mg/kg mod. toxic by skin contact human poison by ing. corrosive irritant to eyes, skin, mucous membranes systemic irritant by inh. common air contaminant TSCA listed Environmental Environmentally hazardous Precaution DOT Corrosive material strong acid mixts. with nitromethane are explosive incompat. with alkalis corrosive to many metals violent reaction possible with sodium tetrahydroborate Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of PO,... 

Environmental Environmentally hazardous Precaution DOT Corrosive material strong acid mixts. with nitromethane are explosive incompat. with alkalis corrosive to many metals violent reaction possible with sodium tetrahydroborate... 

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