Brodie crystallizer-purifier

Brodie Crystallizer-Purifier [Fig. 1414(c)]. This equipment combines a horizontal scraped surface crystallizer with a vertical purifying section. The capacity and performance of the purifier... 

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Brodie Crystallizer-Purifier [Fig, 16.15(c)], This equipment combines a horizontal scraped surface crystallizer with a vertical purifying section. The capacity and performance of the purifier depends strongly on the sizes of the crystals that enter that zone. In order to ensure adequate crystal size, residence times in the crystallizing zone as long as 24 hr may be needed. No data of... 

Figure 16.14. Three types of crystal purifiers with different ways of transporting the crystals, (a) Spiral or screw conveyor type, laboratory scale, but successful up to 200 mm dia [Schildknecht, Z. Anal. Chem. 181, 254 (1961)). (b) Philips purifier with reciprocating piston or pulse pump drive [McKay, Dale, and Weedman, Ind. Eng. Chem. 52, 197(I960)], (c) Combined crystallizer and purifier, gravity flow of the crystals purifier details on the right (Brodie, 1971).

Purifying section 2 Refining section 3 Recovery section 4 Cooling and heating system Figure 9.7 Flow diagram of the Brodie crystallizer... 

A horizontal column is typified by the Brodie Purifier, which is shown schematically in Figure 26. Feed enters the column between recovery and refining sections, and crystals exit the refining section and pass through a purifying section. The purifying section is a wash column in which the crystals are contacted with melt generated at the bottom of the column. 

Fig. 26. Schematic diagram of Brodie Purifier. L = liquid C = crystals (69).

Figure 20-8 shows the features of a horizontal center-fed column [Brodie, Aust. Mech. Chem. Eng. Trans., 37 (May 1979)] which has been commercialized for continuous purification of naphthalene and p-dichlorobenzene. Liquid feed enters the column between the hot purifying section and the cold freezing or recovery zone. Crystals are formed internally by indirect coohng of the melt through the walls of the refining and recoveiy zones. Residue liquid that has been depleted of product exits from the coldest section of the column. A spiral conveyor controls the transport of solids through the unit. 

The horizontal continuous Brodie melt crystallizer is basically an indirectly cooled crystallizer with an internal ribbon conveyor to transport crystals countercurrent to the liquid and a vertical purifier for final refining. Figure 20-8 describes the operation of a single tube unit and Fig. 20-13 depicts a multitube unit. The multitube design has been successfully commercialized for a number of organic chemicals. The Brodie purifier configuration requires careful control of process and equipment temperature differences to eliminate internal encrustations and is limited by the inherent equipment geometry to capacities of less than 15,000 tons per year per module. 

The Brodie Purifier countercurrent cooling crystallizer. (C. IV. Nofsinger Company.)... 

Basically the same idea was used by Brodie (1971) to create the Brodie Purifier of Union Carbide Corp. (GB-PS 1968), which features a horizontally scraped surface crystallizer with a vertical purification section. The performance of the apparatus depends strongly on the size of the crystals entering the purification section. Walas (1988) reports that as much as 24h residence time is needed to create the correct crystal size. He also presents data about p-dichlorobenzene purification. Mullin (1988) reports that in addition to the p-dichlorobenzene, large-scale production has also been installed for naphthalene. Figure 7.20 shows a diagram of the Purifier. 

Drum cascades are not found in large scale. Schildknecht columns never did work when they were too large (larger than laboratory scale), due to problems with axial back mixing and scaling. Since the Brodie purifiers only worked in a few special cases, the TSK process was created. At first glance, the TSK process appears to be continuous, but it is, in fact, a cascade of crystallizers with a purification column. The Kureha purifier and the Nippon Steel BMC work within their companies for special cases or products. 

Brodie purifier. A specific type of continuous melt crystallizer. 

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