Oxidizer tank, atmospheric

LOCAT units can be used for tail-gas clean-up from chemical or physical solvent processes. They can also be used directly as a gas sweetening unit by separating the absorber/oxidizer into two vessels. The regenerated solution is pumped to a high-pres.sure absorber to contact the gas. A light slurry of rich solution comes off the bottom of the absorber and flows to an atmospheric oxidizer tank where it is regenerated. A dense slurry is pumped off the base of the oxidizer to the melter and sulfur separator. 

This type of reactor has developed more recertcly. In Europe, the first examples of implementation were designed for tannery and kraft paper pulp water, i,e. less concentrated in S than spent caustic. Operation at atmospheric pressure and at the only temperature allowed by the exothermic nature of the reactions naturally defines longer reaction times. However, the oxidation tanks built for this type of process are less sensitive to the maintenance and corrosion problems which may affect reactors working at high temperature and pressure. 

In some cases, particularly with iaactive metals, electrolytic cells are the primary method of manufacture of the fluoroborate solution. The manufacture of Sn, Pb, Cu, and Ni fluoroborates by electrolytic dissolution (87,88) is patented. A typical cell for continous production consists of a polyethylene-lined tank with tin anodes at the bottom and a mercury pool (ia a porous basket) cathode near the top (88). Pluoroboric acid is added to the cell and electrolysis is begun. As tin fluoroborate is generated, differences ia specific gravity cause the product to layer at the bottom of the cell. When the desired concentration is reached ia this layer, the heavy solution is drawn from the bottom and fresh HBP is added to the top of the cell continuously. The direct reaction of tin with HBP is slow but can be accelerated by passiag air or oxygen through the solution (89). The stannic fluoroborate is reduced by reaction with mossy tin under an iaert atmosphere. In earlier procedures, HBP reacted with hydrated stannous oxide. 

Shipment Methods and Packaging. Pyridine (1) and pyridine compounds can be shipped in bulk containers such as tank cars, rail cars, and super-sacks, or in smaller containers like fiber or steel dmms. The appropriate U.S. Department of Transportation (DOT) requirements for labeling are given in Table 4. Certain temperature-sensitive pyridines, such as 2-vinylpyridine (23) and 4-vinylpyridine are shipped cold (<—10°C) to inhibit polymerisation. Piperidine (18) and certain piperidine salts are regulated within the United States by the Dmg Enforcement Agency (DEA) (77). Pyridines subject to facile oxidation, like those containing aldehyde and carbinol functionaUty, can be shipped under an inert atmosphere. 

Storage. Purified and dry aHyl chloride can be safely stored in carbon steel vessels. Use of lined vessels is recommended if slight discoloration or trace presence of metals is undesirable for its intended use. In any event, the presence of air should be avoided for safety (flammabHity) reasons through the use of an inert gas pad. Tank vents should be treated, eg, by incineration, prior to venting to the atmosphere. Some commercial producers intentionaHy add about 0.1% propylene oxide as a stabilizer to prevent discoloration however, this is usuaHy unnecessary if product purity is sufficiently high. 

Formation of rust inside a elosed steel tank (oxygen is removed from the atmosphere by the oxidation of iron). 

If brine circuits are open to the atmosphere, air maybe entrained, with consequent oxidation, and the solution will become acid. This will promote corrosion and should be prevented as far as possible by ensuring that return pipes discharge below the tank surface. 

The problem is somewhat different with an oxidizer such as N204. While N204 is compatible with aluminum and many stainless steels, the presence of a small amount of water as an impurity can increase its corrosive characteristics considerably. In addition, if a leak, even of micron size, is present in the propellant tank, a corrosive condition occurs, caused by reaction of the metal with nitric acid, which formed when the N204 contacts water from the surrounding atmosphere. 

B. Diethyl cis-hexahydrophthalate. The reaction is carried out in a low-pressure catalytic hydrogenation apparatus. In a 500-ml. Pyrex centrifuge bottle are placed 0.5 g. of Adams platinum oxide catalyst (Note 5) and 20 ml. of commercial absolute ethanol (Note 6). The bottle is connected to a calibrated low-pressure hydrogen tank and alternately evacuated and filled with hydrogen twice. Hydrogen is then admitted to the system until the pressure is 1-2 atmospheres (15-30 lb.), and the bottle is shaken for 20-30 minutes to reduce the platinum oxide. The shaker is stopped, the bottle is evacuated, and air is admitted. Two hun-... 

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