Solid transfer

Gently warm a mixture of 32 g. (32 ml.) of ethyl acetoacetate and 10 g. of aldehyde-ammonia in a 400 ml. beaker by direct heating on a gauze, stirring the mixture carefully with a thermometer. As soon as the reaction starts, remove the heating, and replace it when the reaction slackens, but do not allow the temperature of the mixture to exceed 100-no the reaction is rapidly completed. Add to the mixture about twice its volume of 2A -hydrochloric acid, and stir the mass until the deposit either becomes solid or forms a thick paste, according to the quality of the aldehyde-ammonia employed. Decant the aqueous acid layer, repeat the extraction of the deposit with more acid, and again decant the acid, or filter off the deposit if it is solid. Transfer the deposit to a conical flask and recrystallise it twice from ethanol (or methylated spirit) diluted with an equal volume of water. The i,4-dihydro-collidine-3,5-dicarboxylic diethyl ester (I) is obtained as colourless crystals, m.p. 130-131°. Yield 12 5 g,... 

Pneumatic conveyors are for high capacity, short distance (400 ft) transport simultaneously from several sources to several destinations. Either vacuum or low pressure (6-12 psig) is employed with a range of air velocities from 35 to 120 ft/sec depending on the material and pressure, air requirements from 1 to 7 cuft/cuft of solid transferred. 

G Zografi, GP Grandolfi, MJ Kontny, DW Mendenhall. Prediction of moisture transfer in mixtures of solids transfer via the vapor phase. Int J Pharm 42 77-88, 1988. 

The unfiltered solute in the molten solid transfers through the porous medium, viz. the P.S.Z., and finally reaches the plane of complete freezing, where it finally solidifies completely. This determines the solute concentration in the treated solid. 

In deriving the material balance equations, the dispersed plug flow model will first be used to obtain the general form but, in the numerical calculations, the dispersion term will be omitted for simplicity. As used previously throughout, the basis for the material balances will be unit volume of the whole reactor space, i.e. gas plus liquid plus solids. Thus in the equations below, for the transfer of reactant A kLa is the volumetric mass transfer coefficient for gas-liquid transfer, and k,as is the volumetric mass transfer coefficient for liquid-solid transfer. 

Fig. 1.22. Solids transfer under an inert atmosphere. (

Naphthylacetonitrile. Place a mixture of 56g (0.32mol) of l-(chloro-methyl)naphthalene, 29 g (0.45 mol) of potassium cyanide, 125 ml of ethanol and 50 ml of water in a 500-ml round-bottomed flask fitted with a double surface reflux condenser, and reflux for 1 hour. Distil off the alcohol, transfer the residue to a separatory funnel, wash it with water, filter from a small amount of solid, transfer to a dish and dry under reduced pressure (vacuum desiccator charged with anhydrous calcium chloride). Distil under diminished pressure and collect the 1-naphthylacetonitrile at 155-160°C/9 mmHg (1) the yield is 38 g (72%). 

Mehta (34) has carried out a reactor network optimization study to find improved designs for the production of acrylonitrile in a collaboration between UMIST and one of its industrial partners. Most industrial installations employ fluidized-bed reactors (BP/Sohio process) with a well-mixed reaction zone. Previous process improvements have mainly resulted from better catalysts, which have produced an increase in yield from 58% to around 80%. The reaction model employed in the optimization study is taken from Ref. 81 and considers seven reactions and eight components. Air, pure oxygen, and propylene are available as raw material streams. The optimization study assumes negligible pressure drop along the reaction sections, isothermal and isobaric operation, and negligible mass gas-solid transfer effects. 

In general, the outlet of an overflow standpipe is immersed into a bed in order to provide an adequate hydrostatic head or seal pressure in the standpipe, as shown in Fig. 8.19(a). The overflow pipe can be operated in either a moving bed or fluidized bed mode. Usually, solids occupy only a fraction of the pipe near the standpipe outlet. The solids flow rate in the pipe depends on the overflow rate from the fluidized bed. Consequently, no valve is needed at the pipe outlet. In the overflow standpipe system where solids transfer from one fluidized bed to the other, the pressure drops across the lower fluidized bed, the grid (distributor), the upper fluidized bed, and the height of solids in the standpipe. For a given standpipe system and given particles, the pressure distribution profile depends on the gas velocity. The difference in the pressure distribution reflects the difference in solids concentration,... 

Knowlton, T. M. (1986). Solids Transfer in Fluidized Systems. In Gas Fluidization Technology. 

Chen, T. Y., Walawender, W. P. and Fan, L. T. (1979). Solids Transfer Between Fluidized Beds A Review. J. Powder Bulk Solids Tech., 3, 3. 

From the usual plate-type distillation and absorption columns, it was but natural to attempt to devise stagewise equipment for G/S processing, for better heat economy and better utilization of the contacting media. But instability of the downcomer for solids transfer between stages remained for many years an unsolved hydrodynamic problem, and even to this data, the stable operation of many solids downcomers still depends on mechanical devices. 

Correlation 7.181 should be used with care at low Reynolds numbers. Typical values for gas-solid transfer are 1 m mi"2 s 1 for the mass transfer coefficient and 102 W m-2 K-1 for the heat transfer coefficient. 

Sample Preparation (for solids) Transfer 50 g of the sample, or a quantity of the sample with a known quantity of sulfur dioxide (500 to 1500 pig of S02), to a food processor or blender, if necessary. Add 50 mL of 5% ethanol in water, and briefly grind the mixture, reserving another 50 mL of 5% ethanol in water to rinse the blender jar. Grinding or blending should be continued only until the food is chopped into pieces small enough to pass through the 24/40 joint of a flask (see Fig. 43). 

A 1-L, three-necked, round-bottomed flask is equipped with a serum cap, a nitrogen inlet tube connected to a T-piece that leads to a prepurified nitrogen supply and to a Nujol bubbler, and a solids-transfer tube (in the center neck). The flask is evacuated, flamed out, and flushed with dry nitrogen. It then is charged with octacarbonyldicobalt (73.4 g, 0.215 mole) and 440 mL of dry tetrahydrofuran (THF). The transfer tube is removed and replaced with an... 

R. Semifluidized or expanded bed. Liquid-solid transfer. Na - T - 2 +1,5 (1 - eL)N Ng fljh, = pN = p/pD [E] l = liquid-phase void fraction, pp = particle density, p = fluid density, dp = particle diameter. Fits expanded bed chromatography in viscous liquids. [64] [159]... 

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