Tank blanketing

Larger volume cycloaUphatic amines and diamines, their worldwide major manufacturers and approximate January 1990 prices are shown in Table 4. Shipment of these Hquid products is by nitrogen-blanketed tank tmck or tank car. Dmm shipments are usually in carbon steel, DOT-17E. 

Deodorized oil must be cooled, saturated with nitrogen, and stored in nitrogen-blanketed tanks (59). The storage tanks can be made of carbon steel. It is not necessary to have stainless steel tanks for freshly deodorized oil with a low free fatty acid content as shown in Table 3. The following guidelines are recommended... 

The best results are obtained when the deodorized oil is cooled to the above recommended temperatures, saturated with nitrogen as it leaves the deodorizer, and stored in nitrogen-blanketed tanks. The headspace in the storage tank should have maximum oxygen content of 0.5% (see Figure 4). 

Both tanks and drums are dangerous when they are empty of liquid toluene but full of vapour. Nitrogen blanketing is always desirable on toluene tanks but it is very important to remember that the atmosphere in a blanketed tank is not fit to breathe from lack of oxygen and thorough ventilation is needed before tank entry. 

Solids recirculation with pumps or impellers takes advantage of the increase in the concentration term (C) in the criterion GCt, to enhance flocculation. There are many designs and these, together with normal floe blanket tanks, are presented by Sontheimer in Ives. Also some discussion of such flocculators and the methods of model testing are described by Stevenson in Purchas ". ... 

Vapor Treatment. The vapors from the tank space can be sent to a treatment system (condenser, absorption, etc.) before venting. The system shown in Fig. 9.1 uses a vacuum-pressure relief valve which allows air in from the atmosphere when the liquid level falls (Fig. 9.1a) but forces the vapor through a treatment system when the tank is filled (Fig. 9.16). If inert gas blanketing is required, because of the flammable nature of the material, then a similar system can be adopted which draws inert gas rather than air when the liquid level falls. 

The areas for the reactors and storage tanks should be separated by fire walls, and must be adequately ventilated. Storage tanks should be blanketed by inert gas. A slight positive pressure of inert gas should be maintained in the reactor or storage tanks during the discharging of the resin or resin solution to prevent air from being sucked into the vessel to form an explosive mixture with the solvent vapor. 

Alkenes with between 4 and 24 carbon atoms react with phenol to produce an unrefined phenol—alkylphenol mixture. This mixture is fed to the distillation train where the phenol is removed for recycle and the product is isolated. The product is then stored in heated tanks made of stainless steel or phenoHc resin lined carbon steel. These tanks are blanketed with inert gas to avoid product discoloration associated with oxidation. 

RCF is sold in a variety of forms, such as loose fiber, blanket, boards, modules, cloth, cements, putties, paper, coatings, felt, vacuum-formed shapes, rope, braid, tape, and textiles. The products are principally used for industrial appHcations as insulation in furnaces, heaters, kiln linings, furnace doors, metal launders, tank car insulation, and other uses up to 1400°C. RCF-consuming industries include ferrous and nonferrous metals, petrochemical, ceramic, glass, chemical, fertiH2er, transportation, constmction, and power generation/incineration. Some newer uses include commercial fire protection and appHcations in aerospace, eg, heat shields and automotive, eg, catalytic converters, metal reinforcement, heat shields, brake pads, and airbags. 

Internal pressure may be caused by several potential sources. One source is the vapor pressure of the Hquid itself. AH Hquids exert a characteristic vapor pressure which varies with temperature. As the temperature iacreases, the vapor pressure iacreases. Liquids that have a vapor pressure equal to atmospheric pressure boH. Another source of internal pressure is the presence of an iaert gas blanketing system. Inert gas blankets are used to pressuri2e the vapor space of a tank to perform speciali2ed functions, such as to keep oxygen out of reactive Hquids. The internal pressure is regulated by PV valves or regulators. 

Siace dimer acids, monomer acids, and trimer acids are unsaturated, they are susceptible to oxidative and thermal attack, and under certain conditions they are slightly corrosive to metals. Special precautions are necessary, therefore, to prevent product color development and equipment deterioration. Type 304 stainless steel is recommended for storage tanks for dimer acids. Eor heating coils and for agitators 316 stainless steel is preferred (heating coils with about 4s m (50 ft ) of heat transfer surface ia the form of a 5.1 cm schedule-10 U-bend scroU are recommended for a 37. 9-m (10,000-gal) tank. Dimer acid storage tanks should have an iaert gas blanket. 

Stainless steel or epoxy-lined tank cars and tank tmcks are recommended for shipping. Aluminum also has been used. The tank can be flushed with carbon dioxide before loading and blanketed with nitrogen after loading. Dmm shipments are recommended in epoxy-lined open-head dmms fitted with a bung. Dimer acids and their by-products contaminated with iron or copper show accelerated color deterioration. Exposure to these metals or their salts should be minimised. 

Ethylene oxide storage tanks ate pressurized with inert gas to keep the vapor space in a nonexplosive region and prevent the potential for decomposition of the ethylene oxide vapor. The total pressure that should be maintained in a storage tank increases with Hquid temperature, since the partial pressure of ethylene oxide will also increase. Figure 5 shows the recommended minimum storage pressures for Hquid ethylene oxide under nitrogen or methane blanketing gas. 

Regulators may be used in gas blanketing systems to maintain a protective environment above anv liquid stored in a tank or vessel as the liquid is pumped out. When the temperature of the vessel is suddenly cooled, the regulator maintains the tank pressure and protects the waUs of the tank from possible collapse. Regulators are known for their fast dynamic response. The absence of time delay that often comes with more sophisticated control systems makes the regulator useful in applications requiring fast corrective action. 

Tanks, Vessels, ana Equipment Flat, curved, and irregular surfaces such as tanks, vessels, boilers, and breechings are normally insulated with flat blocks, beveled lags, curved segments, blankets, or spray-apphed insulation. Since no general procedure can apply to all materials and conditions, it is important that manufacturers specifications and instructions be followed for specific insulation applications. 

Tank depth Clear water zone above dense sludge blanket is determined largely by clarification requirements typicafly 3-5 m. 

Depth tends to be determined from the retention time and the surface overflow rate. As surface overflow rates were reduced, the depth of sedimentation tanks was reduced to keep retention time from being excessive. It was recognized that depth was a valid design parameter and was more critical in some systems than retention time. As mixed-liquor suspended-solids (MESS) concentrations increase, the depth should also be increased. Minimum sedimentation-tank depths for variable operations should be 3.0 m (10 ft) with depths to 4.5 m (15 ft) if 3000 mg/L MESS concentrations are to be maintained under variable hydraulic conditions. With MESS concentrations above 4000 mg/L, the depth of the sedimentation tank should be increased to 6.0 m (20 ft). The key is to keep a definite freeboard over the settled-sludge blanket so that variable hydraulic flows do not lift the solids over the effluent weir. 

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