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Superficial velocity fluid

In Eqs. (Il-53r7) and (11-53/ ), is based on particle diameter and superficial fluid velocity. [Pg.1057]

As indicated by Eq. (12-62) the superficial fluid velocity required for spouting increases with bed depth and orifice diameter and decreases as the bed diameter is increased. [Pg.1224]

Particulate Fluidization Fluid beds of Geldart class A powders that are operated at gas velocities above the minimum fluidizing velocity (L/, y) but belowthe minimum bubbhngvelocity (L/, i) are said to be particulately fluidized. As the gas velocity is increased above L/, y, the bed further expands. Decreasing (p, — Py), d and/or increasing increases the spread between L/, yand U, b until at some point, usually at high pressure, the bed is fully particulately fluidized. Richardson and Zald [Trans. Inst. Chem. Eng., 32, 35 (1954)] showed that U/U = E , where /i is a function of system properties, = void fraction, U = superficial fluid velocity, and Uj = theoretical superficial velocity from the Richardson and Zald plot when = 1. [Pg.1562]

The overall superficial fluid velocity, mentioned earlier, should be proportional to the settling velocity o the sohds if that were the main mechanism for solid suspension. If this were the case, the requirement for power if the setthng velocity were doubled should be eight times. Experimentally, it is found that the increase in power is more nearly four times, so that some effect of the shear rate in macro-scale turbulence is effec tive in providing uphft and motion in the system. [Pg.1633]

Detemiine tlie mean (superficial) fluid velocity, u, as tlie volumetric flowrate divided by die flow channel cross-section. [Pg.739]

Figure 2.9 Fluid flow through porous media Superficial fluid velocity... Figure 2.9 Fluid flow through porous media Superficial fluid velocity...
Few fixed-bed reactors operate in a region where the intrinsic kinetics are applicable. The particles are usually large to minimize pressure drop, and this means that diffusion within the pores. Steps 3 and 7, can limit the reaction rate. Also, the superficial fluid velocity may be low enough that the external film resistances of Steps 2 and 8 become important. A method is needed to estimate actual reaction rates given the intrinsic kinetics and operating conditions within the reactor. The usual approach is to define the effectiveness factor as... [Pg.362]

The fluid pressure drop across the bed versus superficial fluid velocity through the bed would appear as shown in Figure 3.53. [Pg.194]

It is clear that the limit in aZIPi can be easily satisfied in fixed beds with particles larger than about 1 mm, where the bed can be operated in a wide range of superficial fluid velocities up to values in the vicinity of 100 cm/s. [Pg.443]

The empty-pipe Reynolds number is based on the inner pipe diameter and superficial fluid velocity [Eq. (1)]. If the pipe contains a motionless mixer, Eq. (1) needs to be modified to take into account the metal in the mixer, which reduces the effective diameter but increases the fluid velocity (because it blocks part of the cross section). The theoretically sound characteristic dimension for a motionless mixer is the hydraulic diameter, given by... [Pg.243]

Notes a The symbols used include the following D is the diffusion coefficient g is the acceleration due to gravity k is the local mass transfer coefficient v° is the superficial fluid velocity and v is the kinematic viscosity. [Pg.340]

Knowing the viscosity and density of the reaction mixture, the flow channel diameter, void fraction of the bed, and the superficial fluid velocity, it is possible to determine the Reynolds number, estimate the intensity of dispersion from the appropriate correlation, and use the resulting value to determine the effective dispersion coefficient Del or I). Figures 8-32 and 8-33 illustrate the correlations for flow of fluids in empty tubes and through pipes in the laminar flow region, respectively. The dimensionless group De l/udt = De l/2uR depends on the Reynolds number (NRe) and on the molecular diffusivity as measured by the Schmidt number (NSc). For laminar flow region, DeJ is expressed by ... [Pg.733]

Now, the actual linear velocity with respect to the retaining vessel of a fluid flowing through a fluidized bed of voidage e is m0/e, where u0 is the superficial fluid velocity, that is, the volumetric fluid flow rate divided by the horizontal cross-sectional area of the otherwise empty retaining vessel, being positive for the upward direction. Similarly, the actual linear velocity of the particles with respect to the retaining wall is ud/(l - e), where ud is the solid mass flow rate... [Pg.225]

But since the general correlation of classical fluidization is based upon the superficial fluid velocity, the actual relative velocity needs the following conversion to a superficial value ... [Pg.226]

The dimensionless term (9/u0 L, where 9 is the axial dispersion coefficient, u0 is the superficial fluid velocity, and L is the expanded-bed height) is the column-vessel dispersion number, Tc, and is the inverse of the Peclet number of the system. Two limiting cases can be identified from the axial dispersion model. First, when 9/u0L - 0, no axial dispersion occurs, while when 9/u0 L - 00 an infinite diffusivity is obtained and a stirred tank performance is achieved. The dimensionless term Fc, can thus be utilized as an important indicator of the flow characteristics within a fluidized-bed system.446... [Pg.209]

T temperature (°K) T T - fluid and solid temperature, resp. us superficial fluid velocity (m/h) x fractional conversion (CQ - C)/CQ z axjal coordinate (m)... [Pg.245]

Superficial fluid velocity Reactor volume (length3)... [Pg.123]

G. Electrolytic system. Pall rings. Transfer from fluid to rings. Full liquid upflow NA = kLdJD = 4.1N N]ff NsJji/v = 80 to 550 Irrigated liquid downflow (no gas flow) Nsh = 5.1N%lN [E] de = diameter of sphere with same surface area as Pall ring. Full liquid upflow agreed with literature values. Schmidt number dependence was assumed from literature values. In downflow, Njk used superficial fluid velocity. [69]... [Pg.78]


See other pages where Superficial velocity fluid is mentioned: [Pg.1058]    [Pg.1223]    [Pg.321]    [Pg.577]    [Pg.577]    [Pg.638]    [Pg.305]    [Pg.3]    [Pg.49]    [Pg.581]    [Pg.440]    [Pg.143]    [Pg.146]    [Pg.195]    [Pg.309]    [Pg.430]    [Pg.86]    [Pg.127]    [Pg.606]    [Pg.495]    [Pg.196]    [Pg.350]    [Pg.350]    [Pg.77]    [Pg.206]    [Pg.685]    [Pg.110]    [Pg.152]    [Pg.264]   
See also in sourсe #XX -- [ Pg.196 ]

See also in sourсe #XX -- [ Pg.152 ]

See also in sourсe #XX -- [ Pg.834 ]




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