Flashing of Residues

After passing a flash valve, the reactor stream Gjn enters a cyclone held at atmospheric or subatmospheric pressure, where it is split into a vapor stream Gy and a residue stream G,. The reactor stream consists of a liquid portion Gin and a solid portion Gjn, and analogously the residue stream consists of a liquid portion and the same solids as the reactor stream. 

To design or appraise any such process, it is necessary to accurately compute the 

The furfural concentration in the vapor and in the liquid phase of the residue are governed by 

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Simple distillation is not the same as flashing because the vapor is removed out of contact with the liquid as soon as it forms, but the process can be simulated by a succession of small flashes of residual liquid, say 1% of the original amount each time. After n intervals,... 

Secondary alcohols (C q—for surfactant iatermediates are produced by hydrolysis of secondary alkyl borate or boroxiae esters formed when paraffin hydrocarbons are air-oxidized ia the presence of boric acid [10043-35-3] (19,20). Union Carbide Corporation operated a plant ia the United States from 1964 until 1977. A plant built by Nippon Shokubai (Japan Catalytic Chemical) ia 1972 ia Kawasaki, Japan was expanded to 30,000 t/yr capacity ia 1980 (20). The process has been operated iadustriaHy ia the USSR siace 1959 (21). Also, predominantiy primary alcohols are produced ia large volumes ia the USSR by reduction of fatty acids, or their methyl esters, from permanganate-catalyzed air oxidation of paraffin hydrocarbons (22). The paraffin oxidation is carried out ia the temperature range 150—180°C at a paraffin conversion generally below 20% to a mixture of trialkyl borate, (RO)2B, and trialkyl boroxiae, (ROBO). Unconverted paraffin is separated from the product mixture by flash distillation. After hydrolysis of residual borate esters, the boric acid is recovered for recycle and the alcohols are purified by washing and distillation (19,20). 

The burning of the ligneous portion of the black Hquor produces sufficient heat in the furnace to sustain flash drying of residual moisture, salt-cake reduction, and chemical smelting. The heat in the gas passing through the furnace, boiler, and economi2er produces steam for power and process. 

With minor exceptions the requirements for the physical and chemical properties of asphalt were essentially the same for the three national specifications and included penetration and ductiUty at 25 °C flash point % loss at 163 °C penetration of residue as a % of original solubiUty in carbon disulfide solubiUty in carbon tetrachloride specific gravity at 25°C and softening point. 

A flow diagram for the system is shown in Figure 5. Feed gas is dried, and ammonia and sulfur compounds are removed to prevent the irreversible buildup of insoluble salts in the system. Water and soHds formed by trace ammonia and sulfur compounds are removed in the solvent maintenance section (96). The pretreated carbon monoxide feed gas enters the absorber where it is selectively absorbed by a countercurrent flow of solvent to form a carbon monoxide complex with the active copper salt. The carbon monoxide-rich solution flows from the bottom of the absorber to a flash vessel where physically absorbed gas species such as hydrogen, nitrogen, and methane are removed. The solution is then sent to the stripper where the carbon monoxide is released from the complex by heating and pressure reduction to about 0.15 MPa (1.5 atm). The solvent is stripped of residual carbon monoxide, heat-exchanged with the stripper feed, and pumped to the top of the absorber to complete the cycle. 

Refrigeration Loss of containment of a liquefied gas under pressure and at atmospheric temperature causes immediate flashing of a large proportion of the gas. This is followed by slower evaporation of the residue. The hazard from a gas under pressure is normally much less in terms of the amount of material stored, but the physical energy released if a confined explosion occurs at high pressure is large. 

Materials with high flash points sueh as heavy oils and resins ean produee flammable vapours due to thermal degradation on heating. Dangers therefore arise when welding, flame eutting empty drums/vessels onee used to eontain sueh materials due to the presenee of residues. 

The API-RP-520 [10] recommends calculating the amount of vapor flashed and the amount of residual liquid (unfiashed) and then sizing valve orifices for each condition. Select a valve (s) area that has a total area at least equal to the sum of these two areas. Before settling for this approach, this author recommends examining... 

Into a solution of residue 59 (101 mg, 0.1 mmol) in 20 mL of dry toluene, kept at 60°C, was syringed, during 18 h and under argon, a freshly prepared solution of samarium diiodide in benzene-HMPA (9 1, v/v 6.3 mL, 0.51 mmol) which has been diluted with 3.8 mL of dry benzene. The solvents were distilled off under reduced pressure, and the residue was taken up in 10 mL of diethyl ether. The ether solution was washed with 10% aqueous solution of sodium bisulfite, then water, dried (MgS04), and concentrated. The crude product was dissolved in 1.5 mL of tetrahydrofuran and treated during 30 min at room temperature with 1.5 mL of a 40% aqueous solution of HF. The solution was neutralized with solid sodium carbonate, and concentrated. Flash chromatography on silica gel (cyclohexane-ethyl acetate, 3 1 to 1 2) afforded the product 80 (40.6 mg, 50%), a single isomer, as an amorphous solid. It was characterized by its diacetate [a]D +36° (c 4.0, CHClj). 

Care must be exercised in disposing of the waste phos-phorus(III) chloride and the distillation residue. The waste phosphorus(III) chloride may be added in small increments to a large volume of cold water. Each portion is permitted to react and dissolve before the next portion is added. If phosphorus (III) chloride is added to warm water, the reaction is violent and flashes of flame may appear on the surface of the water. 

Flash Point (indicator of residual extraction solvent)—AOCS Method Cc 9c-95(97) (>250°F)... 

Flash Point-Pensky-Martens Closed Cup for Fats and Oils (Cc 9b-55) determines the temperature at which an oil sample will flash when a test flame is applied. This technique sometimes is used to estimate levels of residual hexane and to ensure the safety of workers handling the oil. Some refineries use gas chromatography methods instead. 

After vacuum distillation, a residue of 1 to 2 g. is left in the flask. When air is admitted to the flask, a single flash of light sometimes occurs. In one case, the thermometer and stopper were even blown off the flask. The cause was not determined. 

A regeneration zone in which a liquid extract is introduced from the rectification stage, pre iousiy rid of residual butenes by heating, pressurization and flash. The following are separated in succession during this operation . ... ... 

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