Crystallization From Solution

General References AIChE Testing Procedures Crystallizers, American Institute of Chemical Engineers, New York, 1970 Evaporators, 1961. Bennett, Chem. Eng. Prog., 58(9), 76 (1962). Buckley, Crystal Growth, Wiley, New York, 1951. Campbell and Smith, Phase Rule, Dover, New York, 1951. De Jong and Jancic (eds.), Industrial Crystallization, North-Holland Publishing Company, Amsterdam, 1979. Crystallization from Solution Factors Influencing Size Distribution, Chem. Eng. Prog. Symp. Ser, 67(110),...

Process Design Considerations

Scale-Up of Batch Mixers The prime basis of scale-up of batch mixers has been equal power per unit volume, although the most desirable practical criterion is equal blending per unit time. As size is increased, mechanical-design requirements may limit the larger mixer to lower agitator speeds if so, blend times will be longer in the larger FIG. 18-53 AP Conti paste mixer. (LIST.) FIG. 18-53 AP Conti paste mixer. (LIST.) mixer than in the smaller prototype. If the power is high, the lower...

Gasliquid Systems

Gas-Liquid Dispersion This involves physical dispersion of gas bubbles by the impeller, and the effect of gas flow on the impeller. FIG. 18-23 Relative change in solid-liquid mass-transfer ratio with three different suspension levels, i.e., on-bottom motion, off-bottom motion, and complete uniformity. FIG. 18-23 Relative change in solid-liquid mass-transfer ratio with three different suspension levels, i.e., on-bottom motion, off-bottom motion, and complete uniformity. The observation of the...

Information Required To Specify A Crystallizer

The following information regarding the product, properties of the feed solution, and required materials of construction must be available before a crystallizer application can be properly evaluated and the appropriate equipment options identified. Is the crystalline material being produced a hydrated or an anhydrous material What is the solubility of the compound in water or in other solvents under consideration, and how does this change with temperature Are other compounds in solution which...

Info

FIG. 18-43 Banbury mixer. (Farrel Co.) here that the mixing action takes place. The operation of the rotors of a Banbury at different speeds enables one rotor to drag the stock against the rear of the other and thus help clean ingredients from this area. The extremely high power consumption of the machines operating at speeds of 40 r min or lower calls for rotor shafts of large diameter. The combination of heavy shafts, stubby blades, close clearances, and the confined charge limits the Banbury...

Heating And Cooling Mixers

Heat Transfer Pastes are often heated or cooled by heat transfer through the walls of the container or hollow mixing arms. Good agitation, a large ratio of transfer surface to mixer volume, and frequent removal of material from the surface are essential for high rates of heat transfer. Sometimes evaporation of part of the mix is used for cooling. In most mixers, the metal wall has a negligible thermal resistance. The paste film, however, usually has high resistance. It is important, therefore,...

Components And Accessories For Sedimentation Units

Sedimentation systems consist of a collection of components, each of which can be supplied in a number of variations. The basic components are the same, whether the system is for thickening or clarifying tank, drive-support structure, drive unit and lifting device, rake structure, feedwell, overflow arrangement, underflow arrangement, instrumentation, and flocculation facilities. Tanks Tanks or basins are constructed of such materials as steel, concrete, wood, compacted earth, plastic sheeting,...

Design Of Agitation Equipment

Selection of Equipment The principal factors which influence mixing-equipment choice are (1) the process requirements, (2) the flow properties of the process fluids, (3) equipment costs, and (4) construction materials required. Ideally, the equipment chosen should be that of the lowest total cost which meets all process requirements. The total cost includes depreciation on investment, operating cost such as power, and maintenance costs. Rarely is any more than a superficial evaluation based on...

Classification Of Settleable Solids Sedimentation Tests

The types of sedimentation encountered in process technology will be greatly affected not only by the obvious factors particle size, liquid viscosity, solid and solution densities but also by the characteristics of the particles within the slurry. These properties, as well as the process requirements, will help determine both the type of equipment which will achieve the desired ends most effectively and the testing methods to be used to select the equipment. Figure 18-82 illustrates the...

Fluid Behavior In Mixing Vessels

Impeller Reynolds Number The presence or absence of turbulence in an impeller-stirred vessel can be correlated with an impeller Reynolds number defined FIG. 18-15 Typical flow pattern in a baffled tank with a propeller or an axial-flow turbine positioned on center. FIG. 18-15 Typical flow pattern in a baffled tank with a propeller or an axial-flow turbine positioned on center. FIG. 18-16 Typical flow pattern in a baffled tank with a turbine positioned on center. FIG. 18-16 Typical flow pattern...

Mixing Equipment

Flow Pattern Baffle Tank

There are three types of mixing flow patterns that are markedly different. The so-called axial-flow turbines (Fig. 18-3) actually give a flow coming off the impeller of approximately 45 , and therefore have a recirculation pattern coming back into the impeller at the hub region of the blades. This flow pattern exists to an approximate Reynolds number of 200 to 600 and then becomes radial as the Reynolds number decreases. Both the R100 and A200 impellers normally require four baffles for an...

Circulating Liquor Crystallizers Figure

Crystallizer

18-63 Calculated product-size distribution for a crystallizer operation at different fine-crystal-separation sizes. FIG. 18-64 Forced-circulation (evaporative) crystallizer. (Swenson Process Equipment, Inc.) FIG. 18-64 Forced-circulation (evaporative) crystallizer. (Swenson Process Equipment, Inc.) vaporization to achieve equilibrium between liquid and vapor, the supersaturation which is created causes deposits on the swirling body of suspended crystals until they again leave via the...

Selection Or Design Of A Leaching Process

Hildebrandt Extractor

At the heart of a leaching plant design at any level conceptual, preliminary, firm engineering, or whatever is unit-operations and process design of the extraction unit or line. The major aspects that are particular for the leaching operation are the selection of process and operating conditions and the sizing of the extraction equipment. Process and Operating Conditions The major parameters that must be fixed or identified are the solvent to be used, the temperature, the terminal stream...

Principles Of Crystallization

Diagram Crystallization Machine

Crystals A crystal may be defined as a solid composed of atoms arranged in an orderly, repetitive array. The interatomic distances in a crystal of any definite material are constant and are characteristic of that material. Because the pattern or arrangement of the atoms is repeated in all directions, there are definite restrictions on the kinds of symmetry that crystals can possess. There are five main types of crystals, and these types have been arranged into seven crystallographic systems...

Settling Velocity Ratio

FIG. 18-85 Depth correction factor to be applied to unit areas determined with Wilhelm-Naide and direct methods. Velocity ratio calculated using tangents to settling curve at a particular settled solids concentration and at start of test. would be available in an operating installation or a pilot plant. Continuous units and batch cylinders will produce equivalent results if proper procedures are followed with either system. Thickener-Basin Depth The pulp depth required in the thickener will be...

Leaching Equipment

Rotocel Extractor

It is classification by contacting method that provides the two principal categories into which leaching equipment is divided 1 that in which the leaching is accomplished by percolation and 2 that in which particulate solids are dispersed into a liquid and subsequently separated from it. Each includes batch and continuous units. Materials which disintegrate during leaching are treated in equipment of the second class. A few designs of continuous machines fall in neither of these major classes....

1

Ayres, U.S. Patent 2,531,547, 1950. FIG. 18-30 Injector mixer. Ayres, U.S. Patent 2,531,547, 1950. gravitational conversion factor, 32.2 lbm- ft lbf s2 Ap pressure drop across orifice, lbf ft2 D viscosity of dispersed phase, lbm ft s pav density of dispersed phase, lbm ft and C interfacial tension, lbf ft. See also Shirotsuka et al. Kagaku Kogaku, 25,109 1961 . Valves Valves may be considered to be adjustable orifice mixers. In desalting crude petroleum by mixing with...