Gas injection support

Figure 11.47. Typical designs of gas-injection supports (Norton Co.). (a) Small diameter columns (b) Large...

Packing supports have to support the packed bed physically, while incorporating a large free area to permit free passage of gas and liquid. Grid supports are common, especially in nonmetallic applications. Gas injection supports (Fig. 14) are usually preferred these provide separate passages for the gas and liquid and a large free area. 

FIG. 14-57 Beam-type gas-injection support plate for large columns. 

Rgure 8.2 Action of flat and gas-injection support plates, (a) Flat support plate (6) geis-injection support plate. Reprinted courtesy of Norton Company.)... 

Gas-injection support plates (Fig. 8.3). These have separate openings for vapor and liquid. Vapor issues from the side openings, and liquid flows through the bottom openings, thus avoiding buildup of hydrostatic head (Fig. 8.26). 

The large open area and the separation of vapor from liquid passages are major advantages which make gas-injection support plates most popular. In metallic and plastic applications, this support plate is the least likely to become a capacity bottleneck (142, 212). 

Figure 8.3 Gas-injection support plate. [Reprinted courtesy of Norton Company.)...

In large-diameter columns, gas-injection support plates have the additional advantage of minimizing the number of midspan beams required for supporting the support plate or grid. In metallic application, alternative support t3q>es require two to three times as many support beams 2is the gas-injection plate (74). The author and others (74, 111, 166) recommend specifying gas-injection support plates whenever possible in metallic and plastic random packing applications. 

Grid supports (Fig. 8.4). Grid supports consist of vertical bars arranged on one or two different planes (Fig. 8.4a and d, respectively). Grid supports can often provide as good a performance as (in ceramic applications, even better than) gas-injection supports. 

Grid supports are generally less expensive than gas-injection supports and can provide open areas as high as 70 percent of column cross-sectional area in ceramic applications (305) and 95 to 97 percent in metallic applications (74). Grid supports are commonly used for structured packing, where gas-injection supports are usually unsuitable, and where most of the disadvantages listed below do not apply. 

Grid supports (particularly those whose bars are mounted in a single plane) are more likely to experience packing migration downward than gas-injection supports. Stacking larger packing directly above... 

Midspan beams are normally I-beams installed perpendicular to the support plate beams or grid bars (Fig. 8.6). With gas-injection support plates, midspan supports are usually required in columns larger than... 

---