Stream stripping

Caustic Treatment. Amine treatment may be followed by a caustic treatment step in which the LPG is brought into contact with 10—20 wt % caustic solution to remove any residual H2S and to remove mercaptans. The mercaptans may be stream-stripped from the caustic solution, after which the stripped caustic is recycled to the LPG caustic contactor. Caustics that contain H2S must be discarded. Various promoters maybe added to the caustic to improve the efficiency of the mercaptan removal. 

The anaerobic reaction of sulfur dioxide with aqueous ammonia produces a solution of ammonium sulfite [10192-30-0]. This reaction proceeds efficientiy, even with a gas stream containing as Httie as 1 wt % sulfur dioxide. The sulfur dioxide can be regenerated at a high concentration by acidulation or by stream stripping of the ammonium sulfite solution, or the sulfite can be made to precipitate and the ammonia recovered by addition of lime (243). The process can also be modified to produce ammonium sulfate for use as fertili2er (244) (see Fertilizers). In a variant of this process, the use of electron-beam radiation cataly2es the oxidation of sulfur dioxide in the presence of ammonia to form ammonium sulfate (245). 

Degasser A packed tower through which a fluid to be degassed flows. Air is forced through the fluid stream, stripping the gas from the liquid. 

Following the completion of the polymerization process, the beaded polymer is recovered from the suspension mixture and freed from the stabilizer, diluents, and traces of monomers and initiators. For laboratory and small-scale preparation, repeated washings with water, methanol, or acetone are appropriate. Complete removal of the monomer diluent, solvents, and initiator, especially from macroporous resin, may require a long equilibration time with warm methanol or acetone. In industry, this is usually accomplished by stream stripping. 

Ammonia stripping also removes cyanide, phenols, and other VOCs typically found in cokemaking wastewater. Phenols may also be removed by conversion into nonodorous compounds or into crude phenol or sodium phenolate by either biological means (phenol concentration <25 mg/L) or by physical processes.21 However, the Koppers dephenolization process is considered to be quite effective as it lowers the phenol content by 80 to 90% in ammonia still wastes. In this process a stream stripping process followed by mixing in a solution of caustic soda results in renewal of pure phenol with the flue gas.8... 

Treweek, G. P. and Wogee, J., 1988, Soil Remediation by Air/Stream Stripping In Proceedings of the Hazardous Materials Control Research Institute Fifth National Conference on Hazardous Wastes and Hazardous Materials, April, pp. 147-153. 

There are two processes used to produce EPM/EPDM solution and suspension. In either case a Ziegler-Natta type catalyst is used (aluminum alkyl or aluminum alkyl chlorides and a transition metal salt). The most generally used transition metal is vanadium in the form of the tetrachloride or the oxytrichlo-ride.48 The solution process is similar to that used for other solution polymers. The polymer cement can be finished by stream stripping and drying of the resulting crumb.49... 

In a closed system, equipment that must be repaired should first be cleaned to reduce exposure before the system is opened. Where highly toxic process materials are present, it may be necessary to flush equipment with a low-toxicity stream, strip with steam, and then purge with nitrogen. In such situations, the equipment design should include special fittings necessary for the flushing and purging procedures. 

Thermal desorption involves volatilization of contaminants from soil by heating the soil in various kinds of drying kilns, and is the solid phase analog of air or stream stripping. Temperatures in range 200-500 °C are used. The off-gases must then be treated before release to the atmosphere. This method can be applied to hydrocarbon-contaminated soils and to soils contaminated with organochlorine pesticides (Bunce, 1994). 

The sour-water stripper removes contaminants from condensed water and wash water used in various process units. The water may then be reused, for example, as desalter wash water or to water-wash light gas streams. In this process, the contaminants such as H2S are removed by stream stripping of the water. Figure 9 is a general diagram of a sour-water stripper. 

Stream stripping of naphtha, kerosene, and gas oil side cuts from a crude distillation unit to remove light ends (Vol. 15, pp. 17-18)... 

The high boiling point of 2,3-BD, its high affinity for water, and the dissolved and solid substances of the fermentation broth make it difficult for 2,3-BD to be purified and recovered from fermentation slurry 224). Various methods such as solvent extraction, liquid-liquid extraction and salting out have been used to recover butanediol. Another feasible method to recover butanediol is by countercurrent stream stripping (225). 

Stripping is the opposite of absorption. In stripping, one or more conponents of a liquid stream are removed by being vaporized into an insoluble gas stream. Here the gas stream (stripping agent) must be added as a separating agent. 

Solution Product stream J = l is the nitrogen stream stripped of benzene (almost). Product stream j = 2 is the wash oil stream leaving the absorber after absorbing benzene. Component i = 1 is nitrogen component i = 2 is benzene. In a pseudo-binary calculation scheme, we neglect the wash oil content in f = 2. Similarly, feed stream /i is the nitrogen stream, whereas feed stream is the wash oil stream on a wash oil-free basis. The extent of separation (is... 

Because light products must pass from the feed point up to their respective drawoff point, any intermediate stream will contain some of these lighter materials. Stream stripping (note the group of steam strippers beside the first column in Fig. 15.10) is a way to reintroduce these light materials back into the tower to continue their passage up through the column. 

The objective of one-stage membrane systems as shown in Figure 21.4 is to produce an inert gas purge stream stripped of the vapor component. This can be done with great success, but, because the membrane selectivity is modest, the vapor recycle stream recirculated to the reactor is only modestly enriched, perhaps two- or threefold, in the vapor component. In some applications, this is acceptable in others, a more complete separation is required. The solution is to use two membrane units in series. 

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