Centrifugal static head

Due to the vortex flow in the hydrocyclone, the static pressure in the flow increases radially outward. This centrifugal static head is primarily determined by the distribution of both, the tangential fluid velocities and the suspension densities, within the flow and it constitutes the major contribution to the total pressure loss across an operating hydrocyclone. 

Fig. 6. Illustration of variation of velocity of air at the oudet of a centrifugal fan and the function filled by several diameters of straight discharge duct in converting velocity head to static head and estabUshing normal turbulent dow distribution. Bends or obstmctions at the discharge oudet cause turbulence...

The scale-up of filtration centrifuges is usually done on an area basis, based on small-scale tests. Buchner funnel-type tests are not of much value here because the driving force for filtration is not only due to the static head but also due to the centrifugal forces on the Hquid in the cake. A test procedure has been described with a specially designed filter beaker to measure the intrinsic permeabiHty of the cake (7). The best test is, of course, with a small-scale model, using the actual suspension. Many manufacturers offer small laboratory models for such tests. The scale-up is most reHable if the basket diameter does not increase by a factor of more than 2.5 from the small scale. 

Static head generated by a centrifugal blower depends on RPM alone for a given internal construction and a given set of dimensions. Pressure generated depends not only on RPM, but also on the density of the fluid. Flow depends on conditions outside the blower and so does the power needed. Therefore, blower performance should be characterized first by the head as a function of RPM thereafter, studies can be extended to describe the flow. 

Figure 3-40A. Static head, overall = H + L. (Adapted by permission, Centrifugal Pumps Fundamentals, Ingersoll-Rand Co., Washington, N.J. 07882.)...

It is important to recognize that a centrifugal pump will operate only along its performance curve [10, 11]. External conditions will adjust themselves, or must be adjusted in order to obtain stable operation. Each pump operates within a system, and the conditions can be anticipated if each component part is properly examined. The system consists of the friction losses of the suction and the discharge piping plus the total static head from suction to final discharge point. Figure 3-51 represents a typical system head curve superimposed on the characteristic curve for a 10 by 8-inch pump with a 12-inch diameter impeller. 

Centrifugal pumps, 181 Discharge systems, 187 Example calculation, 186 Flow friction losses, 185. 186 Friction losses, pipe, see Chapter 2 Friction, 188 Pressure head, 184—186 Static head, 184-186 Suction head, 184, 185 Suction lift, 184, 185 Suction systems, 186 Hvdroclones, 265—267 Application system, 267 Ignition, flammable mixtures, 493 Impellers, centrifugal, reducing diameter, 203 Impellers,... 

The problem of separating immiscible liquids in a centrifuge can best be understood by first considering the static gravity separation of immiscible liquids, as illustrated in Fig. 12-5, where the subscript 1 represents the lighter liquid and 2 represents the heavier liquid. In a continuous system, the static head of the heavier liquid in the overflow pipe must be balanced by the combined head of the lighter and heavier liquids in the separator, i.e.,... 

A centrifugal pump is used to pump a liquid in steady turbulent flow through a smooth pipe from one tank to another. Develop an expression for the system total head A/t in terms of the static heads on the discharge and suction sides zd and zs respectively, the gas pressures above the tanks on the discharge and suction sides Pd and Ps respectively, the liquid density p, the liquid dynamic viscosity p, the gravitational acceleration g, the total equivalent lengths on... 

A centrifugal pump consists of a casing in which revolves an impeller, that is a wheel carrying a number of suitably shaped vanes. The centrifugal force sets up a static head in the casing and a certain velocity is imparted to the liquid. With the discharge valve closed only the static head is noticeable and can be... 

Static Head. Fluid elevation above or below the datum line. For horizontal centrifugal pumps, static head is calculated from the pump center line with vertical pumps, it is taken from the eye of the first-stage impeller. 

If the static head is 20 metres, and the pipeline is 100 metres long, one would expect a total system head requirement in the order of 25 metres, so this should be well within the range of available centrifugal pumps, without resorting to 2-pole speed. 

Depending on the way the required pressure drop across the filter medium is generated, surface filters are classified into vacuum, pressure and centrifugal filters. Gravity static head is rarely used in cake filtration, except perhaps for the initial dewatering of highly flocculated sludges in belt presses. 

Figure 6.5 The anaiogy between the static head in a gravity tank (a) and the centrifugal head in a hydrocyclone (b) (note that the hydrocyclone is shown with its axis horizontal)...

Air is compressed to modest pressures, typically 100 to 200 kPa ( 15-30 psig) with either a centrifugal or radial compressor, and mixed with superheated vaporized butane. Static mixers are normally employed to ensure good mixing. Butane concentrations are often limited to less than 1.7 mol 1 to stay below the lower flammable limit of butane (144). Operation of the reactor at butane concentrations below the flammable limit does not eliminate the requirement for combustion venting, and consequendy most processes use mpture disks on both the inlet and exit reactor heads. A dow diagram of the Huntsman fixed-bed maleic anhydride process is shown in Figure 1. 

The impeller (wheel) of the centrifugal compressor imparts kinetic energy to the gas by increasing the gas velocity through the rotation of the impeller. A static pressure rise in the impeller comes from part of this energy, and the balance is converted to velocity head, which in turn converts to additional pressure rise in the compressor wheel assembly. (See Figures 12-43, 12-44B, 12-461, and 12-47.)... 

The static pressure difference will be independent of the fluid flow-rate. The dynamic loss will increase as the flow-rate is increased. It will be roughly proportional to the flow-rate squared, see equation 5.3. The system curve, or operating line, is a plot of the total pressure head versus the liquid flow-rate. The operating point of a centrifugal pump can be found by plotting the system curve on the pump s characteristic curve, see Example 5.3. 

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