Hollow shaft

The Dorr agitator (Coulson and Richardson, loc. cit.) consolidates in one unit the principles of the thickener and the Pachuca tank. Resembling a rake-equipped thickener, it differs in that the rake is driven by a hollow shaft through which the solids-liquid suspension is lifted and circulated by an air stream. The rake moves the pulp to the center, where it can be entrained by the air stream. The unit may be operated batchwise or continuously. 

A basic stirred tank design is shown in Fig. 23-30. Height to diameter ratio is H/D = 2 to 3. Heat transfer may be provided through a jacket or internal coils. Baffles prevent movement of the mass as a whole. A draft tube enhances vertical circulation. The vapor space is about 20 percent of the total volume. A hollow shaft and impeller increase gas circulation (as in Fig. 23-31). A splasher can be attached to the shaft at the hquid surface to improve entrainment of gas. A variety of impellers is in use. The pitched propeller moves the liquid axially, the flat blade moves it radially, and inclined blades move it both axially and radially. The anchor and some other designs are suited to viscous hquids. 

FIG. 23-31 Stirred tank with hollow shaft for hydrogenation of nitrocaprolac-tam, (Dierendonk et al., 5th European Svmp, Chem, React, Eng, Fersamon, 1972, pp. B6 5. )... 

Deepwell turbine pump fitted with a hollow shaft motor Figure 7.3(a)... 

Vertical hollow shaft squirrel cage motor... 

Figure 7.3(b) Vertical hollow shaft squirrel cage motor and its inside view... 

Windmills (induction generators) as an unconventional energy source, vertical hollow shaft motors and submersible pump sets, selection of belts for transmission of load, the phenomenon of shaft currents are discussed. 

Normally the filter strueture consists of a stack of plates attached to a hollow shaft which are mounted inside a pressure vessel with eaeh plate eovered with a suitable filter medium. The slurry is fed under pressure into the vessel and the eake, which is retained by the filter medium, forms on the top of eaeh plate whilst the filtrate passes through the hollow shaft further to the proeess. Filter sizes may vary but generally the maximum is 60 m area and designed for a 6 bar operating pressure. Each circular plate in the staek is eonstructed with radial ribs that are welded to the bottom and support a horizontal eoarse mesh screen whieh is eovered with a fmer woven metal screen or filter cloth to retain the cake. The bottom of the plate slopes towards the hollow eentral shaft whieh lets the filtrate flow freely through circumferential holes and further down the shaft to the filtrate outlet. The elearanee between the plates is maintained by speeial spacers... 

Table 1 lists typical filtering applications and operating ranges. The simplest and oldest types of designs include a series of thin metal disks that are 3-10 inches in diameter and set in a vertical stack with very narrow uniform spaces between them. The disks are supported on a vertical hollow shaft and fit into a closed cylindrical... 

Hohlimg, /. cavity, hoUew, excavation. Hohl-vene, /. (Anat.) vena cava, -walze, /. hollow cylinder or roll, -welle, /. hollow shaft, -zahn, m. (Bot.) hemp nettle, -ziegel, m. hollow brick (or tile), -zirkel, m. inside calipers, -zylinder, m. hollow cylinder. 

Fluid at approximately 60% of discharge pressure is circulated through the bearings and over the rotor tor cooling and lubrication and returns through the hollow shaft to suction pressure. 

Vertical hollow-shaft. (Usually a pump application.) Some manufacturers prefer these to be ordered through manufacturer of driven machine due to complex requirements. 

Remarks Dead-end reactor with a hollow shaft or a nuiltistirrer system possible Internals like disc-donuts or perforated plates can be inserted Internal gas circulation without pumping device possible... 

A gas-inducing agitator system is an alternative to a multistirrer system. It contains a hollow shaft with orifices above the liquid level and a hollow impeller. A typical hollow impeller consists of a tube that is, at the centre, connected to the hollow shaft. Both ends of the impeller are cut at 45 so that, at rotation, the open portions of the tube are at the near side of the stirrer. There are several modifications of this design. Obviously, there is a minimum impeller speed at which the onset of gas induction occurs. Loop reactors are also successfully used. 

The catalysts were obtained from their respective commercial sources and for some of these tests they were subjected to RPT by heating them to 400°C for 2 hours under a flow of hydrogen. The enantioselective ketone hydrogenations were carried out in a 50 ml stainless steel autoclave stirred with a magnetic stirring bar with 10 to 30 mg of catalyst, 10 to 30 mg of MeOHCd, 5 ml substrate and 20 ml AcOH at 60 bar and 25°C for 30 minutes. The crotonic acid hydrogenations were carried out in an ethanolic solution at atmospheric pressure and room temperature stirred at 2000 rpm with a hollow shaft bubbling stirrer. 

Mechanical agitator (hollow-shaft turbine) Medium to high 900Wm 2 K, limited exchange area Heat exchange capacity... 

Modification of the apparatus to accomplish automation is allowed by <711>. One example is hollow shaft sampling as illustrated in Figure 10 (15). This method is theoretically within the stated sampling location of the text of <711>, although there may be question about the concentration of sample surrounding the shaft. This and other sampling techniques, for example in-residence probes, are convenient sampling tools but should be properly validated. 

Figure 10 Hollow shaft autosampler. (Courtesy of Sotax Corporation, Horsham, Pennsylvania, U.S.A.)... 

A mechanical air separator is shown in Figures 1.35 and 1.36. The material is introduced at the top through the hollow shaft and falls on to the rotating disc which throws it outwards. Very large particles fall into the inner cone and the remainder are lifted by the air current produced by the rotating vanes above the disc. Because a rotary motion has been imparted to the air stream, the coarser particles are thrown to the walls of the inner cone and, together with the very large particles, are withdrawn from the bottom. The fine... 

Down shaft Probe positioned down the hollow shaft of the stirring blade in each vessel Eliminates the problem of flow disturbance at the sampling point Sampling depth not as USP-prescribed flow effectiveness through shaft ill-determined... 

The SpinTek technology involves membranes that are bonded to two sides of a disk. Multiple disks are mounted on a hollow shaft that rotates the membranes, and stationary turbulent promoters are mounted near the rotary membranes to create high shear and turbulence. Liquid waste is pumped into the system that hits the spinning disk and spreads across the membrane. Centrifugal force pulls the solid waste outward to the perimeter of the filter disks, where it is removed from the system. By pulling the solids outward, the centrifugal force keeps the filter clear so that the system can run continuously. 

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