Calcium sulfate temperature effect

To increase the value of the demonstration plant, features have been incorporated to permit operation under other than demonstration conditions. It will be possible to operate the evaporator at first-effect temperatures up to 300° F., thus almost doubling plant output if calcium sulfate scale can be prevented, and to use the acid method of scale prevention in place of the sludge method. Provisions have been made for later installation of a vapor compressor, which would convert the plant to a combination multiple effect-thermocompression system. This would add about 15% to plant output and would permit performance evaluation of vapor compressors in sea water service. 

Step B. To the aqueous reaction mixture described under Step A is added 1000-1500 ml. of methanol and the mixture is allowed to stand at room temperature for three hours. The dimethylal and methanol are then distilled out, distillation being stopped when the temjierature of the residue reaches 90°. The mixture is cooled and treated with 10 moles of 40% sodium hydroxide. The amine layer is taken up in ether and the aqueous layer extracted three times with 300 ml. of ether. The ether extract is dried Over anhydrous calcium sulfate and the ether is then removed by distillation. Distillation of the amine is carried out from a Claisen flask, b.p. 82° at 17 mm., 1.5615. Further purification can be effected by distillation through a 12-plate fractionating column. 

The conditions under which the free water is removed arc as important to proper drying as the physical and chemical properties of the sample. These two factors must be considered simultaneously when designing a drying procedure. Drying by controlling the temperature alone would not be reliable because of the effect the relative humidity (RH) has on the amount of water desorbed from the solid surface. However, drying under controlled conditions of temperature and relative humidity may be effective in free water removal only when a pure calcium sulfate is present. 

Where sparingly soluble salts such es calcium carbonate, calcium sulfate, and calcium oxalate are present, they are essentially contaminants that can form scale deposits. The supersaturation potential is caused by both concentration and temperature effects. The inverse solubility characteristic acts to fevor deposition on the heat transfer surface. The contaminant may also be produced by a corrosion effect. 

What is the effect of increase and decrease of temperature and pressure on the scale forming tendency of calcium carbonate and calcium sulfate ... 

B. 2-Methoxycyclooctanone oxime. In a 500-ml., three-necked, round-bottomed flask, fitted with a mechanical stirrer, a dropping funnel, and a reflux condenser equipped with a calcium chloride tube, is placed a solution of 53.5 g. (0.252 mole) of crude 2-chlorocyclooctanone oxime hydrochloride in 250 ml. of methanol. While cooling the vessel with running water, 60.7 g. of triethyl-amine (0.60 mole) is added dropwise during 40 minutes. The reaction temperature is kept below 50° and the reaction is continued for 30 minutes with stirring. After removal of methanol under reduced pressure using an efiicient rotatory evaporator, a light brown semisolid is obtained it is treated with 200 ml. of ether and 200 ml. of water to effect complete solution. The ether layer is separated and the aqueous layer is further extracted twice with ether. The combined ether solution is washed with saturated sodium chloride and dried over sodium sulfate. Removal of ether affords 42.8 g. of crude 2-methoxycyclooctanone oxime (Note 3) as a brown oil. 

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