Packed scrubbers

Packed-bed scrubbers m be construc ted for either vertical or horizontal gas flow. Vertical-flow units (packed towers) commonly use countercurrent flow of gas and liquid, although cocurrent flow is sometimes used. Packed scrubbers using horizontal gas flow usually employ cross-flow of liquid. 

Triple superphosphate, granular SiF, HF, particulate matter Venturi or packed scrubber... 

Problem A 2 ft diameter packed scrubber, removing acetic acid from process offgas had excessive acetic acid emissions causing unacceptable losses and odors. 

Cross-file patent searches, 18 243-244 CrossFire Beilstein, 6 19 Cross-flow filtration, 11 383 15 827, 829 in porous pipes, 11 387-388 with rotating elements, 11 383-387 Cross flow model, 21 706 Cross-flow packed scrubber, 26 687-688 Crossflow plates, 6 762-763 Cross-flow screens, 22 282 Cross-flow velocity, 15 725 Crosshead mandrel, in VDC film extrusion, 25 732-733 Cross-lapping, 17 501 Cross-linkable epoxy thermoplastic system (CET), 10 436... 

From the above, it would appear that the carbon brick is not greatly different in abrasion resistance from the fireclay brick. Where construction requires masonry internals, such as support plates and packed scrubbers, yet the exposures include hydrofluoric acid or strong alkalis, beams, stringers and plates... 

Details on the preparation of pyrolysis oils at SERI in the entrained-flow, fast ablative pyrolysis reactor can be found in a report by Diebold and Scahill (2). The oils in Figure 1 were obtained from two runs, 40 (c and d) and 41 (a and b), the oils being collected from a packed scrubber (a and c) and a cyclone scrubber (b and d). The oil obtained from the packed scrubber in run 41 was subjected to sequential elution by solvents chromatography (SESC) according to the method of Davis et al (7). The HPSEC of fractions 1 through 6 appear in Figure 3. Fraction 1 was eluted with 15% toluene in hexane (yield 0.4%), Fraction 2 was eluted with chloroform (yield 1.5%), Fraction 3 was eluted with 7.5% ether in chloroform (yield 7.5%), Fraction 4 was eluted with 5% ethanol in ether (yield 19.5%), Fraction 5 was eluted with methanol (yield 38.1%), and Fraction 6 was eluted with 4% ethanol in THF (yield 3.1%). The oils displayed in Figures 4 and 5 were produced from run 66. 

Cross flow packed scrubber Ap = 0.3 kPa/m of width 1 to 1.5 m width usual water flowrate 2.7 L/m s of horizontal cross-sectional packing size on actual inlet gas flowrate to the packing face of 1 m /m s. 

Especially with the use of tail gas containing inert gases, not all the HCl may be absorbed in the synthesis/absorption column. After separation of the concentrated acid at the bottom of the column, the gas goes to a packed scrubber, the tails tower, where the absorbing water enters the process. The quality of this water must suit the specified purity of the product acid. The scrubber is elevated, and the dilute solution formed there overflows into the synthesis unit, where it acts as an absorbent. The liquid product emerges at the storage temperature the rate of flow of process water into the system has fixed its strength. 

A packed scrubber with 20 transfer units has been designed to reduce the solute concentration in 80 kmol/h of air from a mole fraction of 0.01 to 0.006. The solute is absorbed into a 20 kmol/h solvent stream, and it can be assumed that the solvent stream enters solute free. If the flow of solvent is decreased by 15%, what is the new outlet mole fraction of solute in air ... 

Prepare a set of performance curves similar to those in Example 18.10 for a packed scrubber with 10 transfer units that removes solute from air from a mole fraction of 0.02 to a mole fraction of 0.001. The flowrate of the inlet air stream is 80 kmol/h, and the solvent flowrate (assumed solute free) is 40... 

Tower packing is used in the scrubbing of corrosive, obnoxious, or hazardous gases, vapors, and particulates from a gas stream. Packed scrubbers have low power requirements and occupy a reasonably small space. They can handle high-temperature and high-moisture content gas streams. Corrosion-resistant construction is readily available. 

Packed scrubbers generally are arranged in one of four ways, based on the manner in which the liquid is contacted with the gas stream. Concurrent flow scrubbers make up two of these classifications. In both cases the liquid and gas flow in the same direction through the scrubber. 

A concurrently operated vertical flow scrubber removes the restriction of power input with respect to hydraulic flooding of the packed bed. Therefore, this device can operate at higher gas velocities and greater pressure drops than a countercurrendy operated scrubber. With increased power input possible, concurrendy operated packed scrubbers are much more effective for the removal of particles from 1- to 3-micron equivalent diameter than countercurrent units. Table 5-2 shows typical size ranges for common particulate emissions [3]. Tobacco smoke has been included in this list to provide a comparison of size with commonly encountered particulates. 

Countercurrently operated packed scrubbers are one method for controlling malodorous emissions. A wet scrubber absorbs the malodorous material into the liquid phase however, many of these substances have limited solubility in water. If the scrubber operates with a once-through water flow, the effluent liquid may be a source of water pollu-... 

Benzene vapor in a coke-oven gas is scrubbed from the gas with wash oil in a countercurrent packed scrubber. The resulting benzenc-wash-oil solution is then heated to I25 C and stripped in a tray tower, using steam as the stripping medium. The stripped wash oil is then cooled and recycled to the absorber. Some data relative to the operation follow ... 

---