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Precipitation processes continuous tubular precipitator

Recent Developments. A considerable amount of cellulose acetate is manufactured by the batch process, as described previously. In order to reduce production costs, efforts have been made to develop a continuous process that includes continuous activation, acetylation, hydrolysis, and precipitation. In this process, the reaction mixture, ie, cellulose, anhydride, catalyst, and solvent, pass continuously through a number of successive reaction zones, each of which is agitated (92,93). In a similar process, the reaction mass is passed through tubular zones in which the mixture is forced through screens of successively small openings to homogenize the mixture effectively (94). Other similar methods for continuous acetylation of cellulose have been described (95,96). [Pg.255]

Chlorinating a slurry of lime in a sodium hydroxide solution forms crystals of calcium hypochlorite dihydrate, which can be filtered and dried. The precipitation of basic compounds is avoided by incremental addition of the calcium hydroxide to the sodium hydroxide solution during chlorination. In a batch process, all of the sodium hydroxide and 10-80% of the calcium hydroxide are introduced into a stirred reactor. Chlorine is then added. When the chlorination is nearly complete, the remainder of the calcium hydroxide is added without interrupting the flow of chlorine. The solids are separated and dried to from CalOCOj. In a continuous process, the sodium hydroxide solution is fed into one end of a long tubular reactor, and the calcium hydroxide slurry and chlorine are separately injected at a number of sites along the length of a jacketed reactor. The calcium hypochlorite is removed from the end of the reactor and dried. When impurities in the lime interfere with the crystallization of calcium hypochlorite, potassium hydroxide is substituted for up to 25% of the sodium hydroxide. ... [Pg.457]

Numerous variations of the interfacial process have been published. The reactions can be carried out in batch in stirred tank reactors or continuously in series of CSTRs and tubular reactors. Intensive mixing with dispersion and redispersion is required throughout the reaction stages. After the reaction is complete, the brine phase is separated and the polymer solution washed to remove residual amine and base. Several processes for devolatilization are in use, including solventless precipitation, steam precipitation, spray drying, falling-strand devolatilization, and vacuum extrusion in devolatilizing extruders. [Pg.95]


See other pages where Precipitation processes continuous tubular precipitator is mentioned: [Pg.336]    [Pg.152]    [Pg.289]    [Pg.529]    [Pg.413]    [Pg.415]    [Pg.204]    [Pg.441]    [Pg.197]    [Pg.336]   
See also in sourсe #XX -- [ Pg.155 ]




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