Fraction distributor

Quench Converter. The quench converter (Fig. 7a) was the basis for the initial ICl low pressure methanol flow sheet. A portion of the mixed synthesis and recycle gas bypasses the loop interchanger, which provides the quench fractions for the iatermediate catalyst beds. The remaining feed gas is heated to the inlet temperature of the first bed. Because the beds are adiabatic, the feed gas temperature increases as the exothermic synthesis reactions proceed. The injection of quench gas between the beds serves to cool the reacting mixture and add more reactants prior to entering the next catalyst bed. Quench converters typically contain three to six catalyst beds with a gas distributor in between each bed for injecting the quench gas. A variety of gas mixing and distribution devices are employed which characterize the proprietary converter designs. 

When a stationary vessel is employed for fluidization, all sohds being treated must be fluidized nontluidizable fractions fall to the bottom of the bed and may eventually block the gas distributor. The addition of mechanical vibration to a fluidized system offers the following advantages ... 

FIG. 14-74 HETP values for Max-Pak structured packing,. 35 kPa (5 psia), two column diameters. Cyclohexane/n-heptane system, total reflux. For 0.4.3 m (1.4 ft) column perforated pipe distributor, 400 streams/m2, 3.05 m (10 ft) bed height. For 1.2 m (4.0 ft) column tubed drip pan distributor, 100 streams/m ,. 3.7 m (12 ft) bed height. Smaller column data. University of Texas/Austin Larger column data. Fractionation Research, Inc. To convert (ft/s)(lb/ft ) to (m/s)(kg/m ) , multiply by 1.2199. (Couiiesy Jaeger Troducts, Inc., Housion, Texas.)... 

Figure 9-9. Liquid maldistribution is a function of opening, shape, and liquid head over the opening for a /s-in. out-of-level distributor. The openings were 3-in. dia. orifice, 3-in. slot, and 22.5° V-notch. Used by permission of The American Institute of Chemical Engineers, Bonilla, J. A., Chemical Engineering Progress, V. 89, No. 3 (1993) p. 47, and with special permission from Fractionation Research, Inc., all rights reserved.

Figure 9-10. Effect of liquid maldistribution on efficiency FRI data for 25-mm Pall rings in cyciohexane/n-heptane distillation with two different quality distributors. Used by permission of the American Institute of Chemical Engineers, Chemical Engineering Progress, Perry, D. and Nutter, ., Jan. (1990) p. 30, and by special permission of Fractionation Research, Inc., all rights reserved.

Figure 9-31 A. Comparison of HETP for No. 2 Nutter Rings and Pall rings in a system at 24 psia and 5 psia using the FRI tubed drip pan distributor. Data prepared and used by permission of Nutter Engineering, Harsco Corp. and by special permission of Fractionation Research, Inc. all rights reserved.

The catalyst must be fluidized to provide an effective seal for the diplegs. Fluidization is critical without it, the diplegs cannot discharge the catalyst and will plug, with possible massive carry-over to the main fractionator. To ensure this uniform fluidization, the system uses an additional steam distributor. 

Table 1. Opening fraction and hole dimension and of the uniform distributor...

Variation of the individual velocities (U ,fd, U pf, Undr and Umb) with opening fraction of the distributor in the conical fluidized beds with the uniform distributor is shown in Fig. 6. With increasing Ug, Umb determined by the optical probe method is well agrees with Umu. However, with decreasing Ug, there is some discrepancy between Umb and Umfd since the optical probe in the lowest part is located 0.05 m above the distributor. 

FIGURE 11.20 Densitogram of alkaloid fraction from Fumaria officinalis herb extract chromatographed in system silica/PrOH -i- AcOH -i- CHjClj (4 1 5) (a) fraction introduced with applicator with evaporation of solvent (b) fraction introduced from the edge of the layer with the eluent distributor. 

In Table II, we explain the meaning of each type of boundary condition. Normally, the bottom distributor is defined as influx cells formulated by fl i, j, k) — 4, where the void fraction is set to a constant value of 0.4. 

For the simulations we use a 2D TFM as described in the previous sections. The simulation conditions are specified in Table V. The gas flow enters at the bottom through a porous distributor. The initial gas volume fraction in each fluid cell is set to an average value of 0.4 and with a random variation of + 5%. Also for the boundary condition at the bottom, we use a uniform gas velocity with a superimposed random component (10%), following Goldschmidt et al. (2004). 

Generally the pressure drop across the plate should be high to promote even gas distribution and is usually some fraction of the pressure drop across the fluidized bed porous distributors tend to have much higher pressure drops than other types of plate. 

Add a quench distributor to the bottom of the main fractionators to control... 

Radioactive tracers [14] are a useful tool to measure unit parameters such as residence times and distribution of the catalyst and vapors in the reactor, stripper, or regenerator. Bypassing can be detected, slip factors calculated and dilute phase residence times are examples of useful calculations that can point the way to future modifications. This technology is also useful for detecting and analyzing equipment malfunctions. Plugged distributors, erratic standpipes, and main fractionator problems such as salt deposits or flooding can be detected with tracers. 

A packed tower can successfully fractionate with a very small pressure drop, as compared to a tray. For a modern trayed tower, to produce one single theoretical tray worth of separation (that s like a single, 100 percent efficient tray), a pressure drop of about 6 in of liquid is needed. A bed of structured packing can do the same job, with one inch of liquid pressure drop, even when allowing for the vapor distributor. In low-pressure fractionators, especially vacuum towers used to make lubricating oils and waxes, this can be of critical importance. 

Packed beds also seem to have a better turndown capability than valve or sieve trays, at low vapor flows. On the other hand, many packed fractionators seem quite intolerant of reduced liquid or reflux flow rates. This is typically a sign of an improperly designed distributor in the packed fractionator. 

As a result, the tower flooded above the holddown plate. To fix this problem, the packing holddown was dropped 15 in below the chimney, orifice plate, distributor. As a result, the tower fractionated properly. 

The juice feed is introduced at the top of the column, on to a distributor disc, and runs down the column in a thinly layered stream between the stators and spinning cone assembly. Counter to its flow and moving up the column is a gas phase, which may be non-intrusive, such as nitrogen, or more commonly a live steam feed. The multiple-stage effect produces a highly efficient separation of the component volatiles from the juice stream and an enriched fraction is produced. 

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