Wire-mesh packings

Other types of RPC have been proposed but are not in industrial use as of this writing. These include a reciprocated wire-mesh packing (188), a reciprocating screen-plate (205), and the multistage vibrating disk column (MVE)C) developed in Japan (189,206,207). These types of RPC may be useful for gas—hquid contact as well as Hquid-Hquid contact. 

FIG. 15-45 Second ScLeiLel extractor witL horizontal baffles and no wire-mesh packing between stages. [Repiinted with peimission of Am. Inst. Chem. Eng. J.,2, 74 (1956)]. 

Filters for mists and droplets have more open area than those used for dry parhcles. If a filter is made of many fine, closely spaced fibers, it will become wet due to the collected liquid. Such wethng will lead to mathng of the fibers, retenhon of more liquid, and eventual blocking of the fiter. Therefore, instead of fine, closely spaced fibers, the usual wet filtrahon system is composed of either knitted wire or wire mesh packed into a pad. A looser filtrahon medium results in a filter with a lower pressure drop than that of the filters used for dry parhculates. The reported pressure drop across wire mesh mist eliminators is 1-2 cm of water at face velocihes of 5 m sec T The essenhal collechon mechanisms employed for filtrahon of droplets and mists are inertial impachon and, to a lesser extent, direct intercephon. 

The Bravo, Fair ei al. correlation for structured pecking. Bravo, Rocha, and Fair (124) developed the first published fundamental model for structured-packing efficiency. This model was developed for the Sulzer BX wire-mesh packing, but has recently (25,50) been extended to... 

For structured packings, tests with the Koch-Sulzer BX and CY wire-mesh packings and with Mellapak 250Y showed no diameter effect on HETP (3,19,32,33). Wu and Chen (167) state that the same applies to Gempak packings. On the other hand, tests with Hyperfil showed an increase in HETP with column diameter (168). 

The monoglycerides of the raffinate (the bottom product) is shown in Figure 9 as a function of the superficial velocity of the gas phase at a phase ratio of 19. At an superficial velocity of 10 mm/s the raffinate obtained with different packings is nearly the same except for the Sulzer Packing SMV. At lower superficial velocities the wire mesh packings (Sulzer CY) provide the best yields. The experiments are made at conditions where a falling film disintegrates into drops. Therefore, it seems understandable that the efficiency of the spray column and that of the collector-distributor installations do not much differ. 

To investigate the effectivity of the installed wire mesh packing in the first regeneration column, the loaded gas can be fed at the bottom section or in the middle of the column. The partially regenerated gas leaves through the top of the column and is again expanded (RV4) and heated (WT2) to reach a complete regeneration. 

Scheibel Extraction Column The original Scheibel column design consisted of a series of knitted-wire-mesh packed sections... 

Small diameter (revamps) Small packing sizes Structured packing Woven wire-mesh packing Natural distribution limits with random packing in small relative diameters... 

Most literature data on the HETS are determined this way. For fatty acid ethyl esters, the average HETS was found to be 0.22 m in a laboratory column (17.5 mm diameter) and 0.27.m for the pilot plant colunm (70 nun diameter) using wire mesh packing (Sulzer EX and Sulzer CY, respectively). Therefore, the laboratory column can be taken as the first guess for tihe HETS, at least for this system. 

---