Pressure mixer

AP, = static mixer pressure drop in turbulent flow, psi... 

P0 = Np = Power number, dimensionless, Equation 5-19 Ppew = Plate coil width, one plate, ft Ap = Pressure drop, psi AP0 = Pressure drop for open pipe, psi AP, = Static mixer pressure drop in turbulent flow, psi Q = Flow rate or pumping capacity from impeller, cu l t/sec, or Ls/1... 

The friction factor is used in the Darcy-Weisbach equation for calculation of pressure drop for turbulent flow in an empty pipe. The mixer pressure drop is given by... 

Mixer pressure drop Mixer pressure drop... 

In more recent work - a simpler method has been used where the pressure drop characteristics are described as a ratio of mixer pressure drop empty pipe pressure drop for the same flow rate and diameter ... 

Mixer Pressure drop Dead spots Barrel wiped Cost of mixer Number of passes Distributive mixing Type of flow... 

Mixers Pressure drop Dead spots Barrei wiped Operator friendly Mbcer cost Disp. mixing Shear strain Splitting, reorient- ing... 

The Froude number wiU be evaluated to determine the suitability of horizontal flow. The pressure drop will then be calculated for both the gas phase and liquid phase flowing separately in the empty pipe. The pressure drop for the combined flow streams will then be determined using the method of Lockhart and Martinelli. Finally, the mixer pressure drop will be determined using the multiplier of the empty pipe pressure drop reported for the SMV mixer specified. 

Design guidehnes for static mixers for this application are not available in the literature and therefore need to be developed through experimentation. Fundamental concepts of gas-liquid contacting in static mixers, discussed in Chapter 7, can be used to select an appropriate mixer type. Since no hterature data are available for the specific fluids at process conditions, it is advised to conduct pilot plant tests at scale at actual pressures to quantify the effect of mixer pressure drop on mass transfer rate and to develop scale-up criteria. 

Fig. 5.80 shows results illustrating behavior in porous medium for a polyacrylamide/Cr(III)/redox system. The data were taken by flowing the gel system at a steady rate through an unconsolidated sandpack. The gel system was mixed at the inlet of the sandpack with an in-line mixer. Pressure drop was measured along the sandpack and converted to apparent viscosity by use of Darcy s law. Apparent viscosity is plotted vs. distance at different times for the gel system up to about 240 hours. 

Motionless inline mixers obtain energy for mixing and dispersion from the pressure drops developed as the phases flow at high velocity through an array of baffles or packing in a tube. Performance data on the Kenics (132) and Sul2er (133) types of motionless mixer have been reported. 

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. 

Pressure drop in static mixers depends very strongly on geometric arrangement of the inserts. It is simply defined in relation to the pressure drop AP in an empty tube given by Darcy s equation ... 

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