Spiral pump

Fig. E6.5b The synthesis of a flat spiral pump from building block 1. (a) A section of the curved channel formed by a stationary plane and the rotating disk plane (b) the extension of the channel into a flat spiral (c) outside view of the flat spiral pump, with the spiral channel machined into the surface of one disk and another closely spaced rotating disk covering it.

Flat Spiral Pump A spiral flight of height H is welded to a stationary disk creating a spiral channel of constant width W, as shown in the accompanying figure. By placing a second disk over the channel, a flat spiral pump is created. Clockwise rotation of the upper disk pumps liquid from the outer inlet port to the inner exit port. Derive an expression for the flow rate of an incompressible Newtonian fluid in isothermal flow. 

The mash is conveyed from the fruit mill to the press, and to and from the heat exchanger, by means of valveless eccentric spiral pumps, large impeller pumps or slow-running piston pumps. 

Thermostat control is no problem in the more expensive compact units with an incorporated column oven. However, a glass or metal jacket fitted around the column, which is then connected to a thermostat bath, is an effective self-help measure. The mobile phase must also be thermostatically controlled by the same bath prior to entry into the column, by means of suitable equipment, e.g. a long spiral. Pumps with thermostatically controlled heads are also available as well as detectors with thermostated cell. 

Especially with LTG GaAs, materials became available that were nearly ideal for time-resolved THz spectroscopy. Due to the low growth temperature and the slight As excess incorporated, clusters are fonned which act as recombination sites for the excited carriers, leading to lifetimes of <250 fs [45], With such recombination lifetunes, THz radiators such as dipole anteimae or log-periodic spirals placed onto optoelectronic substrates and pumped with ultrafast lasers can be used to generate sub-picosecond pulses with optical bandwidths of 2-4 THz. Moreover, coherent sub-picosecond detection is possible, which enables both... 

Applications The common Heliflow apphcations are tank-vent condensers, sample coolers, pump-seal coolers, and steam-jet vacuum condensers. Instant water heaters, glycoLwater seivdces, and cryogenic vaporizers use the spiral tube s ability to reduce thermally induced stresses caused in these apphcations. 

Maintenance The only moving parts in spiral concentrators are those in the pumps that supply the feed and recirculate intermediate products. However, there are sometimes minor maintenance problems associated with the spiral trough itself. Some ores contain sharp particles of veiy abrasive minerals. The presence of these minerals in some ore causes rapid formation of deep grooves in the surface of cast-iron spirals. Wear grooves can be patched with a variety of plastic and metallic cements. Most spirals presently in service are made of cast iron with molded and vulcanized liners. These liners have successfully solved most wear problems. 

Power requirements for spiral plants are low, consisting primarily of pumping energy and possibly a thickener or other pulp-handling equipment associated with the flowsheet. 

Figure 12-113. Typical test results of a medium-capacity spiral lobe compressor vacuum pump using intermeshing lobes. (Used by permission Ingersoll-Rand Co.)...

Like evaporators, RO works on most plating baths and rinse tanks. Most RO systems consist of a housing that contains a membrane and feed pump. There are four basic membrane designs plate-and-frame, spiral-wound, tubular, and hollow-fiber. The most common types of membrane materials are cellulose acetate, polyether/amide, and polysulfones.29... 

A scroll vacuum pump uses two interleaved Archimedean spiral-shaped scrolls to pump or compress gases (see Fig. 1.9). One of the scrolls is fixed, while the other orbits eccentrically without rotating, thereby trapping and compressing gases between the scrolls and moving it towards the outlet. 

The molecules being pumped are dragged along the surface, hence the term molecular drag pump. These surfaces can take the form of a rotating spiralled drum (Holweck) or slotted rotor discs (Gaede). 

Fig. 5.4. Evaporation cryostat for temperatures T > 4.2 K. A mixture of gaseous and liquid 4He is transferred from the storage dewar to the cryostat by means of a transfer tube. The mixture is pumped through a spiral tube which is first thermally anchored to the experiment chamber. The temperature of the experiment can be...

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