Purifiers Brodie

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).

Commercial apphcations for both the Brodie and CCCC process are indicated on Table 22-8. Both the Brodie Purifier and the CCCC processes are available from The C. W. Nofsinger Company, PO Box 419173, Kansas City, MO 64141-0173. 

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. 

Preliminary Design ol Brodie Purifier—Case Study... 

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. 

The Brodie purifier (Brodie, 1971) is a countercurrent melt purification system with the added feature of an imposed temperature gradient between the residue and product outlets. The unit thereby acts as a countercurrent multistage fractionator with partial melting and recrystallization occurring along its length. 

Brodie purifier. A specific type of continuous melt crystallizer. 

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